1
Q
What is the musculature of the GI tract?
A
- skeletal muscle at either end
- smooth throughout rest
2
Q
What is intrinsic rhythmicity in terms of the GI tract?
A
- due to presence of enteric nervous system
- receives input from sympathetic and parasympathetic
3
Q
What are the peptide neurotransmitters present?
A
- bombesin
- motillin
- vasoactive intestinal peptide
4
Q
What are the GI unicellular endocrine cells?
A
- secretes neuropeptides
- derived from endoderm
5
Q
What is the lymphatic tissue found in the GI?
A
-MALT (mucosal associated lymphoid tissue)
+GALT in gut
6
Q
What are the protective mechanisms in the GI?
A
-production of mucus
rapid turnover of epithelial cells in harsh environments
7
Q
Describe lip histology.
A
- lined with mucus membrane lying on vascular FECT -> stratified squamous
- composed of core of skeletal muscle (orbicularis oris)
- internal poorly keratinized, modified, stratified squamous epithelium lies on lamina propria with high papillae
- mixed and mucus glands in lamina
- dermis has rich plexus of capillaries
8
Q
Histology of cheek.
A
-structure similar to lip
-abundant elastic fibers in submucosa
+allows for maximum distensibility to oral mucus membrane
9
Q
What are the three embryonic tissues used to develop the teeth?
A
-ectoderm -> enamel
-neural crest
-mesoderm
+both form dentin, cementum, and pulp
10
Q
How are teeth developed?
A
- dental primordium formed from basal cells of ectoderm
- labiodental lamina is an epithelial shelf that grows the thickened primordium into mesenchyme as a bifid structure
- external limb splits later to form a groove that deepens to separate the lip and the remainder of the mouth
- internal limb is dental lamina
- cells proliferate to form the tooth bud
- later, a second set of tooth buds develops on the lingual side of each developing deciduous tooth -> permanent teeht
11
Q
What is the enamel organ?
A
forms enamel and caps dental papillae
12
Q
What is the dental papillae?
A
-condensation of mesenchyme that gives rise to dentin and pulp
13
Q
What is the dental sac?
A
-CT sac that surrounds the enamel organ and dental papilla and forms cementum and peridontal membrane
14
Q
What are the cells found in tooth development?
A
- odontoblasts
- ameloblasts
15
Q
What do the odoontoblasts do?
A
-form dentin matrix throughout life of tooth
-form single layer of cells lining pulp cavity
-Tomes dentinal fibers
+occupy dentinal tubules
+cyutoplasmic extensions of the odontoblasts continuing through the predentin and dentinal layers to the dentin-enamel junction
-increment lines
16
Q
What is the composition of dentin?
A
- 20% organic matrix
- composed mostly of type I collagen
17
Q
What do ameloblasts do?
A
-forms enamel
+enamel is laid down in prisms -> one per ameloblast
18
Q
What is the hardest substance in the body?
A
enamel
19
Q
What are increment lines of Retzius?
A
-periods of rhythmic growth
20
Q
What is removed after calcification in enamel?
A
- amelogenins
- enamelins
21
Q
How does pulp develop?
A
- originates from dental papilla containing condensed mesenchyme
- consists of fibroblasts, macrophages, peripheral odontoblasts, reticular fibers, nerve fibers, and blood vessels
22
Q
How does cementum form?
A
- cells of dental sac differentiate into cementoblasts which deposit cementum on the dentin of the root
- has Sharpey’s fibers
23
Q
How is the periodontal membrane formed?
A
-CT formed from dental sac with fibroblasts, osteoblasts, cementoblasts, collagen fibers, blood vessels, and nerve fibers
-highly metabolic
-binds cementum to bony socket
-Sharpey’s fibers extend from cementum to alveolar wall
+allows for limited movement
-absorbs pressures of mastication and prevent pressure from damaging alveolar bone
-affected by diabetes and scurvy
24
Q
Histology of tongue.
A
- composed of skeletal muscle, glands, and mucus membrane
- ant. 2/3 of upper oral portion is separated from post. 1/3 by sulcus terminalis
- have lingual papillae
25
What are the four types of papillae?
- filiform papillae
- fungiform papillae
- foliate papillae
- circumvallate papillae
26
filiform papillae
- most numerous, conical
- eveny distributed over entire oral upper portion
- lack taste buds
27
fungiform papillae
- few in number
- mushroom appearance
- interspersed singly among the parallel rows of filliform
- taste buds present only on oral surface of the epithelium in contradistinction to the position of the circumvallate
28
foliate papillae
- rudimentary in humans, but well developed in lower animals
| - pharyngeal portion is free of papillae but contain lingual tonsils
29
circumvallae papillae
- located along sulcus terminalis
- taste buds present on lateral wall
- ducts of von Ebner's glands (serous)
30
What are the taste buds?
- sustentacular cells
| - taste cells
31
What are the sustentacular cells?
-spindle shaped support cells and arranged like barrel staves to surround the inner taste pore at the base
32
What are taste cells?
-long and slender cells with elongated central nucleus and terminates as a short taste hair -> outer taste pore
-possess apical microvilli with taste receptors
distributed between supporting cells
33
How is taste differentiated? Not including bitter
-different signal transduction pathways
-salt and sour utilize ionic transport as signal transduction mechanism
+sour involves hydrogen ion blocjage of K+ channels to cause depolarization
34
How is bitter tasted?
- involves hypopolarized state similar to retinal cell signal transduction -> sweet is hyperpolarized
- involves gustucin
- activation of G subunit, decrease in cGMP, and closure of Na+ channels and hypopolarization of the taste cell
35
What are the 4 layers of the digestive tube?
- epithelium
- lamina propria
- muscularis mucosa
- submucosa
36
What epithelium are found in the GI tube?
- stratified squamous transitioning to simple columnar
| - function dependent on position
37
Composition of lamina propria
- loose areolar CT
| - glands and GALT
38
histology of muscularis mucosa
-made up of three layers of smooth muscle
39
histology of submucosa
- dense, irregular CT
- vascularized
- contains nerve plexus, Meissner's plexus
40
What is the epithelium of the G tract?
- stratified squamous at the ends
- simple columnar most of the length
- glands along the length
41
Difference between innate and acquired immunity.
Innate:
- lacks immune response and specificity
- response -> inflammation
- neutrophils are first responders
Acquired:
- develops in response to antigens
- more powerful than innate immunity
- longer to develop
- displays specificity and memory
42
Passive vs active immunity
passive: temporary immunity due to donated antibodies (transplacental)
active: long lasting/permanent immunity due to self exposure to antigen resulting in memory T cells and B cells specific for antigen
43
Cell mediated vs humoral immunity
cell mediated: T cells, B cells, and antigen presenting cells
humoral: antibody mediated, plasma cells
44
What is primary vs secondary lymphoid tissue? Examples of each
Primary: precursor cells that mature into immunocompetent cells. Each cell is programmed to recognize a specific antigen. Ex. thymus and bone marrow
Secondary: trapped antigens stimulate clonal expansions of mature T and B cells. Ex. lymph nodes, spleen, tonsils
45
Lymphocytes originate in _________ and then take up residence in ____________.
primary lymphoid organs, secondary lymphoid organs
46
Lymph follicles
- not enclosed within a capsule
- occur singly or in aggregates
- are sites of B cell localization and proliferation
- transient
47
primary vs secondary follicles (nodules)
primary: spherical, tightly packed accumulations of virgin B cells and dendritic reticular cells that have not been exposed to antigens
secondary: are derived from primary follicles that have been exposed to nonself antigens, not present at birth
48
In a lymph follicle the _______ is the darker peripheral region composed of densely packed ___ lymphocytes.
The central, light region is called the __________ and is composed of ________, _______, _________, and __________.
corona, B
germinal center, B lymphocytes, memory B cells, plasma cells, and dendritic reticular cells (antigen presenting)
49
How are lymphoid follicles vascularly supplied?
-corona and germinal center are supplied by independent arterioles and venules
50
Where are diffuse and aggregated lymphoid tissue located?
diffuse: located in CT stroma and various other sites (plasma cells, macrophages, and lymphocytes)
+subcutaneous associated lymphoid tissue is found in the papillary layer of the dermis
+lamina propria associated lymphoid tissue
1. MALT
2. BALT
3. GALT
aggregated: beneath and in contact with epithelium (includes tonsils and Peyer's patches in ileum)
51
Where do immune cells originate?
bone marrow
52
Where do T cells travel? B cells?
- thymus
| - lymphoid tissue
53
Maturation of B cells involves what receptors?
- IgM and IgD
- MHC class II proteins
- complement receptors
- Ig Fc receptors
54
What are the 5 classes of antibody? Antibody structure?
5 classes:
IgA, IgD, IgG, IgG, IgM, IgE
```
Structure:
-light and heavy chains
-highly variable regions:
+Fab fragment -> recognizes antigen
-less variable region:
+Fc -> bonds antibody to cells
```
55
Where are the antibodies found?
IgA: saliva, milk, GU, and respiratory
IgD: surface of B cells
IgG: major Ig in blood, most antibody activity
IgE: allergic responses
IgM: first antibody class expressed by developing B cells
56
What is the major histocompatibility complex? Classes MHC genes?
-main function of MHC gene products is the presentation of antigenic peptides to T cells
MHC I: expressed on the surface of all cells except trophoblast and RBCs
MHC II: expressed on the surface of the B cells and antigen presenting cells
57
CD8+ T cells recognize ________ fragments of foreign proteins bound to ______ on the surface of cells.
CD4+ cells also recognize _______ fragments of foreign proteins bound to the _________ on the surface of APCs
- peptide
| - MHC class I
58
What are CD8+ T cells?
- cytolytic T cells
- bind to antigen presenting cells
- undergo mitosis
- release perforins and Fas ligand
- recognize antigens bound to MHC class I
- mediators of cellular immunity
59
What do CD16+ T cells do?
-natural killer cells
-activated to tumor cell antigens and release cytokines
+interleukin-2 (proliferates NK cells)
+interferon-gamma (activates NK)
+macrophage activating cells
+chemotactic factor
+tumor necrosis factor
60
How is T cell mediated immunity activated?
-macrophage phagocytizes material and breaks it down into fragments including antigenic properties (epitopes)
-antigens are expressed on surface of macrophage bound to MHC II
-MHC II/antigen complex is presented to helper T cell
-activated T cell undergoes mitosis
+daughter cells will either become memory cells or secrete interleukins
-T cells attract B cells
- B cells access free antigens and undergo mitosis
+some daughter cells become plasma cells (secrete antibodies) and some are memory cells
61
What is the complement system and what are the two pathways for it?
-an array of about 20 serum proteins which are synthesized in the liver and found in the blood
- classic pathway: cascade activated by antibody binding to pathogen
- alternate pathway: cascade activated by the pathogen
62
The complement system facilitates _________ and involves ________ the pathogen with complement initiating the cascade.
- inflammatory response
| - coating
63
Where does C1q bind?
Fc region of Ig
| ->activates C1r and C1s, initiating complement cascade
64
What does the complement cascade result in?
- activation of membrane attack complex (MAC) on the pathogenleading to perforations and lysis
- production of opsonins, which coatings that make the antigens more palatable to phagocytes
- release of chemotactic agents which attract phagocytes to areas of inflammation of infection
65
Parenchyma vs stroma
parenchyma: consists of cells that typically pack areas of the lymphoid organ -> lymphocytes
stroma: consists mostly pf reticular fibers and cells, including undifferentiated cells and fixed and free macrophages
66
What is the hilus of the lymph node?
-entry and exit point for vessels (afferent lymphatic vessels enter the convex side of the node)
67
What is the capsule of the lymph node composed of?
-dense collagen fibers, elastic fibers, and smooth muscle fibers
68
How many layers does the cortex of the lymph node have? What is inside each?
- outer (lymph folicles)
- deep (contains T cells, macrophages and endothelial venules (port of entry for circulating differentiated lymphocytes to seed lymph nodes)
69
What layers do primary and secondary follicles have?
primary -> neither mantle nor germinal center
secondary -> mantle and germinal center
70
What is in the medulla of the lymph node?
-irregular arrangement of loose medullary sinuses and dense medullary cords
+sinuses are lined with macrophages
+cords consist of blood vessels, lymphoblasts, and plasma cells
-site of lymphocyte reentry into lymph stream
-thymic-dependent areas in subcortical and deeper medullary regions
71
Histology of the thymus
capsule:
- blood vessels
- no lymph vessels
- extends trabeculae into the parenchyma
trabeculae:
- delicate CT
- divide the thymus into incomplete lobules
lobules: outer, darker staining cortex and inner, lighter staining medulla
- > cortex
- cell population (reticular cells (thymosin) and T cells in various stages of differentiation
- thymocytes migrate from cortical areas to medullary areas
- blood vessels surrounded by continuous epithelial barrier (maintain lymphopoiesis while segregated from antigens)
- >medulla
- specialized to aloow entry channel into blood of mature lymphocytes
- capillary beds not sheathed by epithelial cells
72
What are Hassall's corpuscles and where are they found?
-found in medulla of lymph nodes
-whorls of highly keratiized medullary epithelial cells -> produce thymic stromal lymphopoietin
+stimulates thymic dendritic cells needed for the maturation of single positive T cells
73
The thymus is most developed at _________ and contains no ___________, _________, ___________
- puberty
- lymph follicles
- afferent lymph vessels
- lymph sinuses
74
Difference between double negative, double positive, and single positive T cells
double negative:
- lack cell surface molecules typicale of mature T cells
- enter cortex from blood vessels
- proliferate in subcapsular area
double positive:
- confronted with epithelial cells with cell surface MHC classes I and II for clonal selection
- express both CD4 and CD8 coreceptors and TCR receptors
single positive:
-express TCR receptors and either CD4 or CD8
75
What is Foxn-1 and Aire?
- both are transcription factors
- Foxn-1: essential for differentiation of thymic epithelial cells
- Aire:promotes the expression of a portfolio of tissue specific cell proteins by thymic medullary epithelial cells
-these proteins permit the ID and disposal of autoreactive T cells
76
The blood-thymus barrier is located in ___________ and ______ in the blood from reaching developing ________.
Leaky during __________ life to allow fro development of immunologic tolerance to self-antigen.
- thymic cortex
- prevents antigens
- T cells
- fetal life
77
What are the functions of the spleen?
blood filtering functions:
- stores and removes worn out RBCs
- recycles iron
- converts hemoglobin to bilirubin
- blood formation in fetus
immunologic functions:
- screens foreign material in the blood
- produces lymphocytes and plasma cells
- removal leads to overwhelming bacterial infections in infants, children, and young adults
78
What is the white pulp of the spleen?
- elongated, branched strands always associated with arteries
- zones of diffuse lymphoid tissue and germinal centers
- site of clonal expansion of antigen-stimulated lymphocytes
- B cell area contains secondary follicles in which central arteiole is off center
- T cells are found in the areas surrounding the central artery near the center of the white pulp -> FORMS PERIARTERIAL LYMPHATIC SHEATH (PALS)
- reticular fibers are associated with fixed macrophages and support splenic pulp
79
Histology of marginal zone
- forms sinusoidal interface between red and white pulp
- has abundance of antigen presenting cells
- lymphocytes first encounter antigens here
- activated T helper cells activate B cells
80
Histology of red pulp
-surrounds white pulp and makes up 80% of spleen
-filters blood
-billrot cords form red pulp parenchyma
+macrophages destroy worn-out defective RBCs
-venous sinusoids
+storage sites of healthy RBCs
81
What are the functions of the integument?
- protect from mechanical injury
- prevents desiccation
- protects against foreign substances and microorganisms
- protects against UV radiation
- thermoregulation
- regulation of bp
- excretion of metabolic wastes
- synthesis of vitamin D
82
What is the general organization of the integument?
- epidermis
- basement membrane
- dermis
- subcutaneous tissue
- epidermal ridges
83
Primary dermal ridges? Interpapillary peg? Secondary dermal ridges? Dermal papillae?
primary dermal ridge:
- related to finger prints
- everywhere except forehead, external ear, perineum, and scrotum
- formed during 3rd-4th month of fetal life
- subdivided into two secondary dermal ridges by interpapillary peg
interpapillary peg:
-downward growth of epidermis along crest
secondary dermal ridges:
- occur in double rows, branched
- thin, collagenous, reticular, and elastic fibers
dermal papillae:
-upward projections from each secondary ridge
84
What are the layers of the epidermis?
deepest -> superficial
- stratum basale (germinativum)
- stratum spinosum
- stratum granulosum
- stratum lucidum
- stratum corneum
85
What is the difference between thin and thick skin?
- thick skin occurs only on palms and soles -> hairless
| - contains stratum lucidum
86
What two layers make up the stratum Malpighi?
- straum basale
| - stratum spinosum
87
Histology of stratum basale
-columnar to high cuboidal keratinocytes
-keratins 5 and 14
-single layer of cells
-high mitotic activity
+stems cells -> affected by radiation and chemo
88
Histology of stratum spinosum
- polyhedral shaped cells (prickle)
- keratins 1 and 10
- keratohyalin granules develop
- tonofibrils (intercellular bridges)
89
Histology of stratum granulosum
- multilayered
- keratins 2e and 9
- flattened nucleated keratinocytes
- keratohyalin aggregates (cross linkage by disulfide bonds)
- membrane coating granules
- tonofilaments
90
Histology of stratum lucidum
- flat keratinocytes lacking nuclei and organelles
| - contains eleiden
91
Histology of stratum corneum
- multilayered
- thicker in thin skin
- enucleated, flattened, dead keratinocytes
- cytoplasm replaced by keratin
- cytoplasm contains cross linkages with filaggrin
92
Histology of extracellular and intracellular cornified cell envelope
extracellular:
-multi-lamellar lipid layer covalently linked to involucrine
intracellular:
- involucrine
- small proline-rich proteins
- loricrin
- fillagrin and keratin complexes
93
Dermis characteristics
- dense fibrous irregular CT
- mesoderm
- induces development of epidermis and epidermal derivatives
- supports epidermis
94
Characteristics of hypodermis
- loose CT
- corresponds to superficial fascia
- not technically part of skin
- may contain fat cells that can form a thicker layer called the panniculus adiposus
95
What are the two layers of the dermis?
papillary (closest to epidermis)
- loose CT
- separated from epidermis by basal lamina
- elastic fibers and abundant capillaries
reticular:
- dense irregular CT
- fibrocytes, macrophages, and adipocytes
96
Langerhans cells
- dendritic cells
- from monocytes
- antigen presenting cells
- primarily in stratum spinosum
- migrate from epidermis to lymph nodes
97
Merkel cells
- mechanoreceptors
- may also act as diffuse neuroendocrine cells
- usually in stratum basale
- contain catecholamine-like granules
98
Melanocytes
- derived from melanoblasts
- don;t form desmosome attachments in epidermis
- inject melanin granules into keratinocytes
99
What is the pathway for melanin formation?
tyrosine -> 3,4-dihydroxyphenyalanine (DOPA) -> dopaquinone -> melanin
-requires tyrosinase
100
Characteristics of sebaceous glands
- holocrine glands
- branched acinar glands with short ducts
- found everywhere except palms and soles
- continuously produce sebum (released into hair follicle)
- growth is stimulated at puberty
101
Characteristics of sudoriferous glands
- sweat glands
- merocrine and apocrine glands
- > merocrine
- coiled, simple tubular secretory portion
- duct system consists of stratified cuboidal epithelium except in epidermis
- cholinergic ending
- >apocrine
- found in labia majora, areola, and axillary and anal regions
- secretions are thicker and more viscous than merocrine
- open into hair follicle
- adrenergic innervation
- inactive until puberty
- two types (ceruminous glands and glands of Moll)
102
What are the different components of a hair follicle?
- root
- free shaft
- hair follicle
- develop from epidermis as elastic, keratinized threads
103
__________ and ___________ are associated with hair follicles.
- sebaceous glands
| - arrector pili
104
Hair bulbs are expanded lower part of the _____________ and have vascularized ___________.
- hair follicle
| - dermal papilla
105
Histology of external and internal root sheath
```
external root sheath:
-down growth of epidermis
internal root sheath:
-generated by bulb matrix
-layers
+Henle's layer
+Huxley's layer
+cuticle
```
106
Layers of the hair shaft
- medulla
- cortex
- cuticle
107
What cells can reestablish epidermis in severely burned patients? What pathways are involved?
-kertinocyte stem cells
migration pathways:
- bulb-epidermis stem cells pathway
- bulb-sebaceous gland stem cell pathway
- bulb-hair stem cell pathway
signaling pathways:
- Wnt signaling pathway
- Notch signaling pathway
108
What are the cardiac tunics?
-endocardium
+innermost layer, lining atria and ventricles
+components -> endothelium and subendothelial CT
+continuous with the tunica intima of the blood vessels entering and leaving the heart
+subendocardium is a layer located between the endocardium and the myocardium (nerves and Purkinje fibers)
-myocardium
+consists of cardiac muscle cells
-epicardium
+external surface is covered by simple squamous epithelium
+mesothelium overlies fibroelastric CT containing adipose cells, nerves, and coronary vessels
109
What composes the cardiac skeleton?
- dense collagenous CT
| - myocardial fibers originate and insert into cardiac skeleton
110
What are the vascular tunics of the blood vessels?
-tunica intima
+endothelium and basal lamina (found in all arteries and arterioles, produce von Willebrand;s factor VIII)
+subendothelial CT (found in elastic and muscular arteries and some arterioles)
+internal elastic membrane (incomplete in elastic arteries but thick and complete in muscular arteries)
-tunica media
+made up of circular smooth muscle tissue and fibroblasts
+contains collagen and elastic fibers
-tunica adventitia
+outermost layer (lacking in arterioles)
+consists of loose areolar tissue
+contains irregular fibroelastic tissue with adipocytes
+has small vessels and nerves
111
What are elastic arteries?
- conducting arteries
- stretch during systole and recoil during diastole
- tunic media consists of elastic fibers organized into elastic laminae
- aorta, pulmonary trunk, large branches of aorta
112
What are muscular arteries?
-distributing arteries
-tunica media consists of smooth muscle that responds to autonomic stimulation adn hormones
+thickness of smooth muscle layer decreases as diameter becomes smaller
113
What are arterioles?
--tunica media consists of one to three layers of smooth muscle cells
-mean arterial pressure depends on proper tone of smooth muscles in arterioles
+thickness of smooth muscle layer decrease as diameter becomes smaller
-rise to metarterioles
114
Veins compared to arteries
- larger lumen, thinner walls, valves are present in many veins
- larger veins have a layer of longitudinal smooth muscle in the inner aspect of the tunica adventitia
115
What does the respiratory mucosa consist of?
- pseudostratified ciliated columnar epithelium (lines conducting surfaces)
- lamina propria (thin layer of loose CT)
- submucosa (dense irregular CT)
116
Epithelium of the nare
- stratified squamous epithelium continuous with epidermis
| - contains sebaceous glands, sudoriferous glands, and hair follicles
117
Where are the olfactory epithelium located?
- nasal cavity roof
- pseudostratified columnar without goblet cells
- no distinct basement membrane
118
What are the different cell types found in the olfactory epithelium?
-sustentacular cells with pigment granules
-basal cells with pigment granules
+stem cells
-olfactory cells
+bipolar neurons
+knoblike ending with nonmotile cilia
+cilia possess G protein linked odor specific receptors
+basal end of the cell extends as an unmyelinated axon, bundled with other similar axons, through the ethmoid plate to mitral cells located in the olfactory bulb
+dead ones are replaced ffrom basal cells
-olfactory glands of Bowman
+located in the lamina propria
+secrete odorant binding protein
+odorant binding protein binds to odorant molecule in nasal cavity
119
How is an olfactory AP created?
odorant binding protein + odorant molecule -> binds to odorant receptor protein (G protein) on olfactory cell cilium -> G protein activated adenyl cyclase -> ATP -> cAMP -> opening of Na+ channels -> AP
120
Nasopharynx histology
mucosa: respiratory epithelium, lamina propria with FECT, mucus glands, serous and mixed glands, adn diffuse lymphatic tissue
submucosa: loose CT, MALT
Waldeyer's ring: ring of lymphoid tissue around nasopharnyx, tonsils and adenoids
121
Histology of larynx
Epiglottis
lingual surface: covered with stratified squamous epithelium, lamina propria with loose CT and elastic
pharyngeal surface: covered with pseudostratified ciliated epithelium, lamina propria with tubuloacinar seromucus glands
False vocal cords
- covered with pseudostartified ciliated epithelium
- lamina with seromucus glands
True vocal cords
- covered with stratified squamous epithelium
- lack seromucus glands in lamina propria
122
Tissues of the larynx
epithelium:
- respiratory epithelium (pseudostratified ciliated columnar)
- stratified squamous epithelium
cartilage:
- hyaline -> thyroid, cricoid, arytenoids
- elastic cartilages -> corniculates, cuneiforms, tips arytenoids, epiglottis
muscle:
-skeletal muscle
123
Layers of trachea
mucosa:
- respiratory epithelium with thick basement membrane
- lamina propria with delicate FECT and lymphatic tissue
submucosa:
-many seromucus glands
adventitia:
- 16-20 horseshoe shaped cartilages interconnected by FECT
- opening between arms of horseshoe shaped cartilages closed by (FECT, mucus membrane, and smooth muscles)
- mixed glands and capillaries
124
bronchi
- circular cartilaginous rings and resemble rings (hyaline cartilage)
- referred to as extrapulmonary
- the primary bronchi branch into three (right) or two (left) secondary bronchi
125
Histology of bronchi
mucosa:
- similar to trachea and extrapulmonary bronchi
- mucosal folds may be present due to smooth muscles
- elastic fibers are prominent
submucosa:
- characterized by loose CT and lymphatic tissue
- contains mixed glands and mucus glands
adventitia:
-contains hyaline cartilage plates surrounded by dense FECt
126
Characteristics of bronchioles
- absence of cartilage
- absence of glands
- sparse goblet cells, especially in terminal bronchioles
- large amount of smooth muscle tissue
- epithelium transitions from ciliated columnar with a few goblet cells to ciliated cuboidal with no goblet
- smallest bronchioles are the terminal bronchioles
- each terminal bronchiole branches to form 2+ respiratory bronchioles
127
Characteristics of respiratory bronchioles
- epithelium of low columnar to low cuboidal
- cilia present only in larger bronchioles
- no goblet cells
- smooth muscle with FECT
- alveolar outpocketings
128
Composition of alveolar ducts
- continuation of respiratory bronchioles
- cone shaped
- squamous epithelium
- wall consists of smooth muscle with FECT
129
Alveoli within alveolar sacs are separated by alveolar septa. The walls of these septa are thin and composed of what?
-type I alveolar cells (type I pneumocytes)
+cover largest SA
-type II alveolar cells
+cuboidal or rounded
+stem cells for type I and II pneumocytes
-macrophages
130
What are the opening between adjacent alveoli called?
-pores of Kohn
131
What are the different cells types found in the mucosa?
- ciliated columnar cells
- nonciliated columnar cells (microvilli)
- stem cells (basal cells of pseudostratified epi)
- goblet cells
- neuroendocrine cells (sensory and release catecholamines)
132
What secretes surfactant? What does surfactant do?
- Clara cells and type II alveolar cells (phagocytie old surfactant)
- reduces surface tension on alveolar surface
133
Type pneumocytes I vs type II pneumocytes
type I:
- thin cytoplasm
- cover 95% of alveolar surface
- tight junctions connect with other type I cells
- basal lamina may be fused with basal lamina of nearbby capillaries
type II:
- rounded cells that bulge into the alveolar lumen
- cover 5% of the alveolar surface
- divide and replace type I cells
- produce phospholipid protein surfactant
134
Clara cells are only found in the __________. Number of Clara cells _________ as ciliated columnar cells __________. They have an abundant _______.
- bronchioles
- increases, decreases
- SER
135
What are dust cells?
- macrophages derived from monocytes
| - phagocytize pollutants, bacteria, and surfactant that are not trapped in the mucus
136
How are dust cells related to congestive heart failure?
- in CHF, fluid containing the breakdown products of hemoglobin leak into the alveolar spaces and are phagocytized by the dust cells
- iron-containing dust cells are referred to as heart failure cells
137
What does the blood-air barrier consist of? What does is do?
- thin capillary endothelium
- -thin epithelium of pneumocyte
- intervening basal lamina produced by both cell types
-permits gas exchange but does not allow fluids or cells to enter alveoli
138
What is the functional unit of the kidney? What are the components?
- nephron
- renal corpuscle (Bowman's capsule and glomerulus)
- renal tubule
139
Where does the collecting duct empty?
-renal pelvis
140
What are the two different types of nephrons?
- cortical nephrons: renal corpuscles of these nephrons located in the cortex, short loops of Henle that do not extend into medulla
juxtamedullary: renal corpuscles in cortex next cortical-medullary junction, long loops of Henle -> empty into vasa recta
141
outline the vascular supply of the kidney
interlobar arteries -> arcuate arteries -> interlobular arteries -> afferent arterioles -> glomeruli -> efferent arterioles -> vasta recta or peritubular capillaries -> interlobular veins -> arcuate veins -> interlobar veins -> renal vein
142
Where does the efferent arteriole feed into?
- capillary loop, vasa recta
| - capillary network, peritubular capillaries
143
What makes up the glomerulus?
- afferent arteriole (juxtaglomerular cells -> renin)
- efferent arteriole
- glomerular formation of capillaries
144
Describe the layers of Bowman's capsule
-parietal layer:
+outer layer of simple squamous epithelium
+continuous with simple cuboidal of proximal convoluted tubule
-visceral layer:
+inner layer of podocytes in contact with endotheliun of glomerular capillaries
145
What is the renal corpuscle? What process occurs here?
- involved in producing a filtrate of blood
| - reabsoption
146
What is the mesangium?
- formed mesangial cells embedded in mesangial matrix
- located between nearby capillaries in the glomerulus and cover endothelium not covered by podocytes
- associated with juxtaglomerular apparatus
147
Characteristics and functions of mesangial cells
- contractile -> modify blood flow through glomerular capillaries
- phagocytic: take up worn out glomerular basal lamina for recycling and immunoglobins trapped in the basal lamina
- proliferative
- synthesize matrix and collagen
- secrete prostagladins and endothelins
- respond to angiotensin II
- provide mechanical support and regulate bloof flow
148
Components of the juxtaglomerular apparatus
- macula densa
- extraglomerular mesangial cells
- juxtaglomerular cells
149
Macula densa
- formed by elongated, densely packed cells in the walls of the convoluted tubule. Polarity reserved.
- responds to changes in Na and Cl conc in urine or hypotension
- signals renin release from juxtaglomerular cells
- involved in regulation of fluid-electrolyte balance and blood pressure regulation
150
Juxtaglomerular cells
- modified smooth muscle cells associated with macula densa
- secrete renin when stimulated by macula densa
- innervated by sympathetic nerve endings which increase renin release
151
Renal tubule parts
- proximal convoluted tubule
- loop of Henle
- distal convoluted tubule
152
Components of the renal filtration barrier
- fenestrated endothelium of glomerular capillaries
- fused basal lamina of endothelial cells and podocytes
- filtration slits
153
What is reabsorbed via the glomerulus?
- water, glucose, and most ions
- NO proteins
- NO large, negatively charged ions
154
Characteristics of proximal convoluted tubule
- simple cuboidal epithelium
- apical tight junctions and brush border
- basolateral striations with abundant mitochondria
- large, pale staining nuclei
- eosinophilic cytoplasm
155
Functions of proximal convoluted tubule
- reabsorbs most filtrate
- removes essentially all glucose and aa from filtrate
- reabsorbs most of the sodium and chlorine
- complex set of transporters, cotransports, channels, and exchangers
156
Composition of ascending and descending LoH
- thick segments of LoH: simple low cuboidal, no brush border
- thin segments of LoH: simple squamous
157
Functions of LoH
- descending: permeable to water and Na+ and Cl-
- ascending: impermeable to water and actively pumps Cl- ions (Na+ follows)
- major function is to establish the counter-current exchange system which creates the osmotic conditions necessary to pull water out of the distal convoluted tubule and collecting duct in the presence of ADH.
158
Characteritics and functions of distal tubule
- lined with simple cuboidal
- large lumen than proximal, no brush border
- cytoplasm less eosinophilic
- impermeable to water except in presence of ADH
159
Where is ADH derived from?
posterior pituitary
160
What are the two specialized cell type in the collecting duct? What do they do?
principal cells: reabsorb Na+ and water and secrete K+ via ATPase pump
intercalated cells: secrete either H+ or HCO2+
161
Characteristics of renal mucosa
-transitional epithelium, basement membrane, lamina of FECT, lymphoid tissue and smooth muscle cells
162
Characteristics of renal muscularis
- inner longitudinal and outer circular smooth muscle coat in ureter
- lower third of ureter has external longitudinal coat
- layers of smooth muscle in bladder form detrusor muscle
163
What are the different sections of urethra in the male?
prostatic urethra:
- section of urethra passing through prostate gland
- transitional
- highly vascularized with veins with abundant elastic tissue
membranous urethra:
- tall pseudostratified columnar cells
- urogenital diaphragm and receives striated muscle cells forming external sphinctor
cavernous urethra:
-lined with pseudostratified epithelium with patches of stratified squamous
164
What glands are in the male urethra?
- lacunae of Morgagni: invaginations of mucus membrane containing single or groups of intraepithelial mucus cells
- glands of Littre: branched glands opening into Morgagni
165
Outline the renin-angiotensin-aldosterone system
angiotensinogen -(renin)-> angiotensin I -(ACE)-> angiotensin II -> stimulates secretion of aldosterone from adrenal cortex
- aldosterone acts on principal cells and ascending limbs of Henle
- increases reabsorption of Na+ and water, increasing bp
- stimulates release of ADH
166
Muscularis externa of digestive tube
- inner smooth muscle (circular)
- outer longitudinal
- myenteric nerve plexus lies between the two layers
- regulates size of lumen
- rhythmic movement of GI tract
167
what composes the outer most layer of the digestive tube?
serosa
- dense irregular CT
- consists of mesothelial lining and submesothelial CT
- visceral peritoneum
- adventitia
- dense irregular CT
- covers retroperitoneal portions of digestive system
168
What two plexi are found in the gut wall under the parasympathetic system?
-Meissner's plexus:
+regulates local secretions, blood flow, and absorption
-Auerbach's plexus:
+coordinates muscular activity of gut wall
169
_______ is the first line of defense and is found coating the luminal surface of the mucosal epithelium. What other lymphoid tissues are found in the gut?
- IgA
- lymph follicles are found in the lamina propria
- aggregated lymphoid follicles form the tonsils of the oropharynx
170
Functions of the esophagus and structural specializations
Functions:
- digestion
- addition of mucus to food bolus
```
Structural specializations:
-mucosa
+stratified squamous, mucus glands
-muscularis extrerna
+undergoes transition from skeletal muscle in upper 1/3 to mixture of skeletal and smooth in middle 1/3 and smooth in lower 1/3
```
171
Epithelial lining of stomach
- gastric mucosa has simple columnar with mucus columnar cells
- rugae are longitudinal mucosal folds that are most prominent in empty stomach
- mucus secreted to protect stomach
- three layers of smooth muscle (third layer is inner oblique layer)
172
What are the different regions of stomach?
- cardia (mucus glands)
- fundus (gastric glands)
- body (gastric glands)
- pylorus (mucus and hormone secreting enteroendocrine cells)
173
What are the gastric glands of the stomach? Which is zymogenic, oxyntic, and APUD cells?
- mucus cells
- stem cells
- chief cells (pepsinogen) -> zymogen
- parietal cells (HCl and intrinsic factor) -> oxyntic
- enteroendocrine cells -> APUD
174
What are parietal cells?
- pyrimidal shape, eosinopjilic cell
- produces HCl and intrinsic factor
- generates H+ from carbonic acid similar to osteoclast
175
Chief cell
secretes pepsinogen
176
Enteroendocrine cell
-produce peptide hormones and serotonin
177
What structures increase the surface area of the GI tract?
- length of small and large intestine
- plicae circularis
- villi
- microvilli
178
What are the three orders of folding in the intestine?
- plicae (folds of the mucosa)
- crypt-villus system
- microvilli (glycolipid coat, contains brush border enzymes)
179
Structure of microvilli
-supported by core of actin microfilaments
+actin filaments are tied to terminal web intermediate filaments via spectrin fibrils
+actin filaments are bound to plasma membrane covering villus via membrane linking proteins (myosin I and calmodulin)
+cross linked with each other via villin and fimbrin
180
What are the different areas of the small intestine?
- duodenum
- jejunum
- ileum
181
Layers of intestinal wall (inside to outside)
- mucosa with lamina propria and muscularis mucosa
- submucosa
- muscularis layers
- serosa
182
Histologic characteristics of the duodenum
- villi with wide spatulate or leaflike distal shape
- deep crypts of Lieberkuhn
- Brunner's glands with excretory ducts in submucosa
183
What are the crypts of Lieberkuhn?
- simple tubular glands within the intestinal mucosa
| - open between adjacent villi and extend to muscularis mucosa
184
What cells are in the crypts of Lieberkuhn?
-goblet cells
-enterocytes
+disaccharides
+absorption of proteins, carbs, lipids
+enzymes present of apical brush border for carb digestion
+produce enteropeptidase which is for activation of pancreatic zymogens and proenzymes
-paneth cells
+produce lysozyme to control intestinal flora, prominent eosinophilic granules
-enteroendocrine cells
+agyrophilic
+produce peptide hormones and serotonin
+produce paracrine or autocrine secretions
+formed from stem cells in all regions of GI
185
What are the glands of Brunner?
- found in submucosa of duodenum
| - responsible for formation of bicarbonate and mucus -> neutralizes gastric acid
186
Histologic characteristics of the jejunum
- villi longer and narrow
- crypts of Lieberkuhn present
- no glands in submucosa
187
Histologic characteristics of the ileum
- villi longer and narrow
- crypts of Lieberkuhn present
- no glands in submucosa
188
Epithelium and functions of the large intestine
Epithelium
- simple columnar epithelium
- crypts but no villi
Functions:
- secretion of mucus for lubrication
- goblet cell prominent
- absorption of fluid
- formation of fecal matter
- continuation of digestion
189
FECT
fibrous elastic CT
190
What are the characteristics of paneth cells?
- basophilic basal cytoplasm
- supranuclear Golgi complex
- large, intensely acidophilic apical secretory granules
191
What do paneth cells secrete?
- lysozyme to increase permeability of bacteria by degrading peptidoglycan coat
- defensins to increase permeability of target organisms
- tumor necrosis factor alpha
- may phagocytize some microorganisms and help regulate intestinal flora
192
What secretes mucus and what are the two layers of mucus in the intestines?
- goblet cells
- outer layer containing microorganisms
- inner layer with antimicrobial proteins that resist microbial penetration
193
Explain the immune surveillance system
- antigen binds to toll-like receptor on enterocyte surface
- B cell activating factor is produced
- B cells in lamina propria mature into plasma cells (antibodies)
- antigen is taken up by M cells associated with Peyer patch in the intestinal mucosa
- antigens transported to lymphocytes located in pocket folds of M cells
- antigens are bound to Ig receptors on surface of lymphocytes
- lymphocytes transfer antigen to dendritic cells in lamina propria
- dendritic cells interact with T cells in lamina propria to activate immune response
194
WHat is the majority of the body's immune defenses centered around?
-GALT
195
What is GALT?
-transitory aggregations of lymphocytes, neutrophils, eosinophils
appendix
-Peyer's patches
-mesenteric lymph nodes
196
What are Peyer's patches?
- dome shaped lymphoid structures under the mucosal surface
- B and T cell dependent areas
- high endothelial venules which facilitate entrance of lymphocytes into lymphoid organs from the bloodstrea,
- covered by M cells
- phagocytize and present antigens
197
What are M (microfold) cells?
-sample particulate antigen and present it to antigen-presenting cells in the underlying lamina propria
198
What immunoglobulin is produced by GALT?
IgA and sIg (secretory)
- does not stimulate the complement system, but functions by coating microorganisms (inhibit binding to epithelium)
- secreted and synthesized by plasma cells
199
Rapid cell turnover in most of GI tract, esophagus and anus, SI, LI, and stomach
most of GI:
- true of stomach and SI
- lining replaced every 5 days
esophagus and anus:
-new cells are formed in basal layer of stratified epithelium and migrate through sub-basal levels to be sloughed off into the lumen
small intestine:
-new cells are formed in the crypts from undifferentiated cells
large intestine:
-no villi, so proliferative compartment is found at the base of the crypts
```
stomach:
-stem cells found in neck of gastric glands
-difffrenctitate into:
+parietal cells
+enteroendocrine cells
+chief cells
+surface and neck mucus cells
```
200
Outline the digestion of carbs
- salivary amylase -> starch hydrolyzed to disaccharides
- disaccharides broken down into monosaccharides in brush border of SI
- monosaccharides absorbed by enterocytes (Na+ dependent sugar glucose transporter 1, SGLT-1)
201
Where is amylase synthesized?
pancreas
202
Outline protein digestion
- begins in stomach, proteins hydrolyzed into peptides through pepsin
- polypeptide breakdown occurs in SI involving trypsin, chymotrypsin, elastase, and carboxypeptidase (pancreas)
- these enzymes activated by enteropeptidase (enterokinase)
- breakdown of oligopeptides to aa occurs in intestinal brush border
- transport of aa into enterocytes via a carrier-mediated process
203
Outline lipid digestion
-begins in SI -> TAG droplet
-pancreatic lipase emulsifies and releases FAs and glycerol (bile salts to form micelle)
-micelles are passively absorbed across enterocyte apical plasma membrane (requires FA binding proteins)
-monoglycerides and glycerol are reesterfied in the enterocyte SER to form TAGs
+requires acyl-CoA synthetase and acyltransferase
-TAGs recombine with proteins to form chylomicrons and are taken up by central lacteals -> cisterna chyli -> lymph ducts -> subclavian veins
204
How do carbs and proteins enter the blood vessels?
through the villi and transported to liver via the hepatic portal system
205
Where is cholecystokinin secreted?
-upper intestinal mucosa (duodenum) -> secreted in response to gastric contents
206
What are the targets and effects of cholecystokinin?
- acts on pyloric sphinctor to slow down emptying of stomach
- stimulates bile release from gallbladder
- stimulates secretion of pancreatic enzymes
- inhibits gastrins
207
Site of secretion of gastrin
pyloric-antral portion of the stomach
208
Target and effects of gastrin
- stimulates HCl production by gastric parietal cells
- promotes growth of gastric mucosa
- stimulates gastric motility
- stimulates release of insulin by pancreatic beta cells
209
Where is secretin secreted?
-epithelial cells of duodenum -> stimulated by acid contents of stomach
210
Targets and effects of secretin
- enhances release of insulin by pancreatic beta cells
| - stimulates bicarbonate secretion by pancreas
211
Epithelium and muscle in the anal canal
- stratified squamous epithelium
| - skeletal muscle as external anal sphincter
212
What organ has exocrine and endocrine secretory function?
pancreas
213
What is the main excretory duct in the pancreas? Small accessory duct?
- duct of Wirsung
| - duct of Santorini
214
What composes the interlobular ducts?
-simple columnar epithelium and goblet cells
215
What cells are found in the intercalated ducts?
- lined with low cuboidal cells
- have receptors for secretin
- cells secrete water and bocarbonate
216
WHich of the following best describes the olfactory mucosa?
a) stratified columnar epithelium with goblet cells and a distinct basement membrane
b) simple ciliated columnar epithelium with goblet cells and a distinct basement membrane
c) stratified, non keratinized epithelium lacking goblet cells with thick basement membrane
d) pseudostratified columnar epithelium lacking goblet cells with no distinct basement membrane
d
217
WWhich of the following is NOT a necessary part of the respiratory membrane?
a) pneumocyte I\
b) basal lamina of pneumocyte I
c) dust cells
d) basal lamina of endothelial cell
e) endothelial cell
c
218
Which of the following is characteristic of an arteriole?
a) thick tunica adventitia and large lumen
b) thick tunica media in relation to size of lumen
c) thin tunica media and relatively large lumen
d) large blood filled lumen
e) large amounts of elastic fibers in tunica media
b
219
Where in the body of a normal, healthy individual would you expect most errythrophagocytosis to be occurring?
-cord of Billroth in spleen
220
Which of the following sequences best describes the flow of RBCs through the spleen?
a) trabecular a, central a, splenic a, penicillus, venous sinuses
b) splenic a, central a, trabecular a, venous sinuses, penicillus
c) trabecular a, splenic a, central a, penicillus, venous sinuses
d) splenic a, trabecular a, central a, penicillus, venous sinuses
d
221
The simple cuboidal epithelium of this portion of the kidney tubule is composed of cells in the form of truncated pyramids which are characterized by basal striations that mark the location of mitochondria.
a) proximal convoluted tubule
b) descending LoH
c) ascending LoH
d) distal convoluted tubule
e) collecting duct
a
222
Renin is secreted by which of the following?
a) liver
b) macula densa
c) atrial cells of the heart
d) mesangial cells
e) juxtaglomerular cells
e
223
Acini are _______. Acinar cells are _______ ________ cells.
- serous
| - pyramidal serous
224
Characteristics of acinar cells
- basophilic basal zone (nucleus and RER)
| - apical zone with zymogens (trypsin, chymotrysin, amylase, and lipase, receptors for cholecystokinin)
225
Characteristics of centroacinar cells
- form a truncated cuboidal epithelium within lumen of acini
- continuous with the epithelium of the intercalated duct
- unique to pancreas
226
Describe the structure of the acinus structure.
- no striated ducts
- no myoepithelial cells
- release of digestive enzymes from serous acinar cells stimulated by CCK
- bicarbonate rich, alkaline fluid released by ductal epithelial cells in response to secretin
227
Where are digestive enzymes concentrated and stored?
vesicles in the Golgi of the pancreas (zymogen granules)
228
What controls the synthesis and secretion of the zymogens in the pancreas?
- peptides secreted by the duodenal enteroendocrine cells
| - synthesized as inactive proenzymes on RER of acinar cells
229
What hormone controls bicarbonate regulation?
secretin
230
What do the islets of Langerhans do?
-endocrine cell aggregation interspersed irregularly among the acici
-contain:
+alpha cells:glucagon
+beta cells: insulin, more numerous than alpha cells
+delta cells: somatostain (helps control levels of insulin and glucagon)
231
What is the space of Disse?
- separates hepatic cells from endothelial cells
| - active in transfer between blood and parenchyma
232
What is the space of Mall?
- continuous with the space of Disse
| - drains into lymphatics
233
How are lobules distinguished?
- CT septa extend from capsule to form lobes and lobules
| - Glisson's thin capsule of FECT covers the surface except at the diaphraphmatic attachment
234
How many lobes are in the liver?
4
235
Classic hepatic lobule
- central venule is in the center of the lobule
| - portal triads are at the angles
236
portal hepatic lobule
- 3 central venules of adjacent lobules form a triangle
| - portions of the bile canaliculi of the three lobules drain into the same bile duct
237
Liver acini hepatic lobules
- includes 3 zones defined by hepatic tissue receiving blood from a branch of the hepatic artery conducting blood to the opposite central veins
- metabolic gradient extends from hepatic triad to central vein
238
Where is the portal triad? Components???
- found at angles of classic lobule
- branch of hepatic artery -branch of portal vein
- bile duct
239
Describe a hepatocyte
-polyhedral
-central nucleus with 1+ nuclei
-cytoplasm may contain glycogen, fat droplets, and pigment granules
-basolateral domain
+microvilli
+faces space of Disse
+involved in absorption of blood borne substances, secretion of plasma proteins
-apical domain
+borders bile canaliculi
240
Hepatic sinusoids
- fenestrated endothelial cells
| - discontinuous basal lamina
241
Perisinusoidal cells
-located in space of Disse
-store vitamin A
-produce collagen fibers and extracellular matrix compoenents
-during cirrhosis:
_transform into myofibroblasts
+
242
Subendothelial space of Disse
- space between basal lamina and hepatocytes
- contains microvilli of basolateral domain
- contains types I, III, IV collagen
- contains interstitial fluid and space of Mall
243
Kuppfer cell
- phagocytic cells -> monocytes
| - lines hepatic sinusoids
244
bile canaliculi
- extracellulart canal located between two rows of hepatocytes -> receives bile from hepatocytes
- canal of Herring
- received bile from canaliculus
245
neck of gallbladder
-mucosal folds form spiral valve of Heister -> flow of bile out of gallbladder
246
wall of gall bladder
-mucosa:
-tall columnar with striated border
-lamina propria of CT has extensive vascular plexuese and may contain a few smooth muscle cells
-Rokitansky-Aschoff sinuses are small
-muscularis
-smooth muscle seprated by CT
-serosa
-
247
Major ducts in liver
- cystic duct
- hepatic duct
- common bile duct
- lined with columnar epithelium with goblet cells
- no definite pattern of muscle
Histology- Erin
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