1
Q
how do the four types of tissues in the human body contribute to homeostasis?
A
provides diverse functions including protection, support, communication among cells, resistance to disease, etc.
2
Q
what are the structure and properties of a specific tissue influenced by?
A
factors such as the nature of the extracellular material that surrounds the cells and the connections between the cells that compose the tissue
3
Q
what are tissues?
A
group of cells that usually have a common embryonic origin and function together to carry out specialized activities
4
Q
what are the four types of tissues?
A
epithelial, connective, muscular, and nervous
5
Q
what are epithelial tissues?
A
tissues that cover body surfaces and lines hollow organs, body cavities, and ducts, and forms glands
6
Q
what do epithelial tissues allow the body to do?
A
allows the body to interact with both its internal and external environments because they have a free/apical surface
7
Q
what are connective tissues?
A
- tissues that protect and support the body and its organs
- bind organs together, store energy tissues as fat, helps the body by providing immunity to disease-causing organisms
8
Q
what are muscular tissues?
A
tissues composed of cells specialized for contraction and generation of force, generates heat in the process that warms the body
9
Q
what are nervous tissues?
A
tissues that detect changes in a variety of conditions inside and outside the body and responds by generating electrical signals called nerve action potentials/nerve impulses that activate muscular contracts and glandular secretions
10
Q
what are some key differences in function among the four tissue types?
A
11
Q
what is a biopsy?
A
removal of a sample of living tissue for microscopic examination
12
Q
what do biopsies do?
A
procedure is used to help diagnose many disorders, especially cancer, and to discover the cause of unexplained infections and inflammations
13
Q
why are biopsies sometimes conducted during surgery?
A
helps physician determine most appropriate treatment
ex: if thyroid tissue reveals malignant cells, surgeon can proceed immediately with most appropriate procedure
14
Q
what are cell junctions?
A
contact points between plasma membranes of tissue cells
15
Q
what are the four types of cell junctions?
A
- tight junctions
- adhering junctions
- desmosomes
- hemidesmosomes
- gap junctions
16
Q
what are tight junctions?
A
junctions consisting of weblike strands of transmembrane proteins that fuse together the outer surfaces of adjacent plasma membranes to seal off passageways between adjacent cells
17
Q
what is the function of tight junctions?
A
- inhibits passage of substances between cells
- prevents contents of organs from leaking into blood or surrounding tissues
18
Q
where can you find tight junctions?
A
where leakage is not desirable
- epithelial cells that line stomach, intestines, and urinary bladder
19
Q
what are adhering junctions?
A
junctions that contain plaque and cadherins as well as actin microfilaments, often forming adhesion belts because they encircle the entire cell
20
Q
what is plaque?
A
dense layer of proteins on the inside of the plasma membrane that attaches both to membrane proteins and to actin microfilaments of the cytoskeleton
21
Q
what are cadherins?
A
transmembrane glycoproteins
- inserts into the plaque from the opposite side of the plasma membrane, partially crosses the intercellular space, and connects to cadherins of an adjacent cell
22
Q
what is the function of adhering junctions?
A
helps epithelial surfaces to resist separation during various contractile activities, like when food moves through the intestines
- to stick cells together
23
Q
where can you find adhering junctions?
A
in the intestines
24
Q
what are desmosomes?
A
- contain plaque and cadherins but the plaque does not attach to microfilaments and instead attaches to intermediate keratin filaments, plaque is discontinuous
- the keratin microfilaments extend from desmosomes on one side of cell across the intracellular fluid to desmosomes on the opposite side of the cell, contributing to stability of the cells and the tissue
25
what is the function of desmosomes?
prevents epidermal cells from separating under tension and cardiac muscle cells from pulling apart during contraction
26
where can you find desmosomes?
common among cells that make up the epidermis and among cardiac muscle cells in the heart
27
what are hemidesmosomes?
- similar to desmosomes but do not link adjacent cells
- contains integrins which attaches to keratin on the inside of cell membrane
- integrins attach to laminin present in the basement membrane on the outside of cell membrane
28
what is the function of hemidesmosomes?
anchors cells not to each other but to the basement membrane
29
what are gap junctions?
- junctions where connexins form connexons that connect neighbouring cells
- plasma membrane are separated by narrow intercellular gap
30
what are connexins?
membrane proteins present in gap junctions
31
what are connexons?
tiny-fluid filled tunnels that connect neighbouring cells, present in gap junctions
32
what is the function of gap junctions?
- ions and small molecules can diffuse through connexons
- passage of large molecules such as vital intracellular proteins is prevented
- allows cells in a tissue to communicate with one another
- enables nerve or muscle impulses to spread rapidly among cells
33
where can you find gap junctions?
- avascular tissues such as the lens and cornea of the eye
- tissues where rapid communication is needed, such as parts of the nervous system and for the contraction of muscle in the heart, gastrointestinal tract, and uterus
- in developing embryo, where signals that regulate growth and cell differentiation travel through gap junctions
34
which types of gap junctions are found in epithelial tissue?
- adhering junctions
- hemidesmosomes
- tight junctions
35
which type of cell junction prevents the contents of organs from leaking into surrounding tissue?
tight junctions due to the lack of intercellular space
36
what are some major structural differences between an epithelial tissue and connective tissue?
in epithelial:
- cells tightly packed together
- avascular
- no extracellular matrix
- has a free/apical surface
in connective:
- cells far away
- vascular
- a lot of extracellular matrix
- no free/apical surface
37
why are epithelial tissues and connective tissues almost always found immediately adjacent to each other?
epithelial lacks blood vessels, so is next to vascular connective tissue, enables it to make exchanges with blood necessary for the delivery of oxygen and nutrients and the removal of wastes
38
why is there little intercellular space between adjacent plasma membranes of epithelial cells?
cells are closely packed together and are held tightly by many cell junctions
39
what are the two types of epithelial tissues?
1. surface epithelium
2. glandular epithelium
40
what is surface epithelium?
covers or lines a surface in the body exposed to the outside
41
where can you find surface epithelium?
- outer covering of skin and internal organs
- inner lining of blood vessels, ducts, body cavities
- lining of respiratory, digestive, urinary, and genital surfaces
42
what is glandular epithelium?
epithelial tissue that makes up the secreting portion of glands
43
what are the functions of glandular epithelium?
- protects
- secretes (mucus, hormones, enzymes)
- absorbs (nutrients in digestive canal)
- excretes (various substances in urinary tract)
44
where can you find glandular epithelium?
- thyroid gland, adrenal glands, sweat glands, digestive glands
45
what are the surfaces of surface epithelium?
- apical/free surface
- lateral surface
- basal surface
46
what is the apical surface?
- most superficial layer
the surface of an epithelial cell that faces the body surface, a body cavity, the lumen of an internal organ, or a tubular duct that receives cell secretions
- may contain cilia or microvilli
47
what is the lateral surface?
- the surface of an epithelial cell that face adjacent cells on either side
- may contain tight junctions, adhering junctions, desmosomes, gap junctions
48
what is the basal surface?
- opposite to the apical surface, most deep layer
- deepest layer of epithelial cells adhere to extracellular materials like the basement membrane
- hemidesmosomes anchor epithelium to the basement membrane
49
how do basement membranes become thickened?
increased production of collagen or laminin, thickening in small blood vessels leads to reduced function
50
what is the basement membrane?
thin, extracellular layer that commonly consists of two layers, the basal lamina and reticular lamina
51
what is the function of the basement membrane?
- attaches and anchors the epithelium to the connective tissue
- forms a surface along which epithelial cells migrate during growth or wound healing
- restricts passage of larger molecules between epithelium and connective tissue
- participates in filtration of blood in kidneys
52
what is the basal lamina?
layer closest to, and secreted by, the epithelial cells
- contains laminin, collagen, glycoproteins, proteoglycans
53
what function does the protein laminin have in the basal lamina?
laminin adheres to integrins in hemidesmosomes and thus attaches epithelial cells to the basement membrane
54
what is the reticular lamina?
layer closest to connective tissue
- contains collagen produced by fibroblasts
55
what process allows for exchange of substances between epithelial tissue and connective tissue?
diffusion, does not require ATP and relies on kinetic energy of molecules
56
why is epithelial tissue constantly being renewed?
- epithelial tissues are subjected to physical stress and injury, thus they form boundaries within the body's organs, or between the body and the external environment
- high rate of cell division allows them to constantly renew and repair by sloughing off dead/injured cells and replacing them with new ones
57
what happens when epithelial tissue and nervous tissue combine?
special organs are formed for smell, hearing, vision, and touch
58
what are some of the most important functions of epithelial tissue?
- protection
- filtration
- secretion
- absorption
- excretion
59
what is simple epithelium?
single layer of cells
- diffusion, osmosis, filtration, secretion, absorption
60
what is secretion?
production and release of substances such as mucus, sweat, enzymes
61
what is absorption?
intake of fluids or other substances such as digested food from the intestinal tract
62
what is pseudostratified epithelium?
simple epithelium, single layer of cells where cell nuclei lie at different levels and not all cells reach apical surface
63
what is stratified epithelium?
two or more layers of cells that protect underlying tissues in locations where there is considerable wear and tear
64
what are squamous cells?
thin, flat epithelial cells which allow for rapid passage of substances through them
65
what are cuboidal cells?
epithelial cells as tall as they are wide, shaped like cubes/hexagons
- may have microvilli on apical surface
- function in secretion/absorption
66
what are columnar cells?
epithelial cells much taller than wide, like columns
- protect underlying tissues
- may have cilia/microvilli
- often specialized for secretion/absorption
67
what are transitional cells?
epithelial cells that change shape
ex: cells in urinary bladder stretch/distend to a larger size and collapse to a smaller size
68
what is endothelium?
simple squamous epithelium that lines the cardiovascular and lymphatic system (heart, blood vessels, lymph vessels)
69
what is mesothelium?
simple squamous epithelium that forms epithelial layer of serous membranes of abdominal and thoracic cavities ( peritoneum, pericardium, pleura)
70
what are the two types of stratified squamous epithelium?
nonkeratinized and keratinized
71
which cell shape is best adapted for the rapid movement of substances from one cell to another?
squamous epithelial cells - flat and thin
72
what is simple squamous epithelium?
single layer of flat cells, centrally located nucleus that is flattened and oval or spherical in shape, resembles tiled floor when viewed from apical surface
73
what is the function of simple squamous epithelium?
present at sites of filtration or diffusion and at site of secretion in serous membranes
- not found in body areas subjected to mechanical stress
74
what is simple cuboidal epithelium?
single layer of cube-shaped cells, centrally located nucleus
75
what is the function of simple cuboidal epithelium?
secretion and absorption
76
where can you find simple cuboidal epithelium?
makes up secreting portion of some glands (thyroid) and ducts of some glands (pancreas)
77
what is nonciliated simple columnar epithelium?
single layer of nonciliated columnlike cells with oval nuclei near base of cells
- contains columnar epithelial cells with microvilli at apical surface and goblet cells
78
what are microvilli?
fingerlike cytoplasmic projections that increase surface area of plasma membrane, increasing cell's rate of absorption
79
what are goblet cells?
modified columnar epithelial cells that secret mucus at their apical surfaces
80
where can you find nonciliated simple columnar epithelium?
- lines digestive canal (from stomach to anus)
- ducts of many glands
- gallbladder
81
what is the function of nonciliated simple columnar epithelium?
secretion and absorption
- secreted mucus lubricates linings of digestive, respiratory, and genital tracts and most of urinary tract
- helps prevent destruction of stomach lining by acidic gastric juice secreted by stomach
82
why are columnar cells capable of higher level of secretion and absorption than cuboidal cells?
larger, contain more organelles
83
what is ciliated simple columnar epithelium?
single layer of ciliated columnlike cells with oval nuclei near base of cells, goblet cells are usually interspersed
84
where can you find ciliated simple columnar epithelium?
lines some bronchioles of respiratory tract, uterine tubes, some paranasal sinuses, central canal of spinal cord, and brain ventricles
85
what is the function of ciliated simple columnar epithelium?
- cilia beat in unison, moving fluid across cell surfaces
- secretion of mucus also allows for lubrication of lining
86
what is nonciliated pseudostratified columnar epithelium?
- appears to have several layers, nuclei of cells are at various levels
- all cells attached to basement membrane but some do not reach apical surface
- lacks goblet cells
87
where can you find nonciliated pseudostratified columnar epithelium?
lines epididymis, larger ducts of many glands, and parts of male urethra
88
what is the function of nonciliated pseudostratified columnar epithelium?
secretion and absorption
89
what is ciliated pseudostratified columnar epithelium?
- appears to have several layers, nuclei of cells are at various levels
- all cells attached to basement membrane but some do not reach apical surface
- contains cells that extend to surface and secret mucus or bear cilia
90
what is the function of ciliated pseudostratified columnar epithelium?
secretes mucus that traps foreign particles, and cilia sweep away mucus for elimination from body
91
where can you find ciliated pseudostratified columnar epithelium?
lines airways of most of upper respiratory tract
92
what is stratified squamous epithelium?
two or more layers of cells, cells in apical layer and close to it are squamous
93
how is stratified squamous epithelium renewed?
- as basal cells divide, daughter cells arising from cell divisions push upward to apical surface
- as they move away from blood supply in connective tissue, they become dehydrated and less metabolically active
- tough proteins predominate as cytoplasm reduced, cells become tough hard structures that eventually die
94
what is keratinized stratified squamous epithelium?
stratified squamous epithelium that developed tough layer of keratin in apical layer of cells
- relative amount of keratin increases in cells as they move away from nutritive blood supply and organelles die
95
what is keratin?
tough, fibrous intracellular protein that helps protect skin and underlying tissues from heat, microbes, and chemicals
96
what is nonkeratinized stratified squamous epithelium?
stratified squamous epithelium that does not contain large amounts of keratin in apical surface
- constantly moistened by mucus from salivary and mucous glands
- surface cells do not die in epithelium, shed before they die
97
where can you find stratified squamous epithelium?
keratinized: superficial layer of skin
nonkeratinized: wet surfaces (lining of mouth, esophagus, part of epiglottis, part of pharynx) covers tongue
98
what is the function of stratified squamous epithelium?
protection against abrasion, water loss, UV radiation, foreign invasion
- first line of defense against microbes
99
what is stratified cuboidal epithelium?
two or more layers of cells, cells in apical layer are cube-shaped, fairly rare
100
where can you find stratified cuboidal epithelium?
ducts of adult sweat glands and esophageal glands, part of male urethra
101
what is the function of stratified cuboidal epithelium?
protection, limited secretion and absorption
102
what is stratified columnar epithelium?
basal layers usually consist of shorted irregularly shaped cells, only apical layer has columnar cells, uncommon
103
where can you find stratified columnar epithelium?
lines part of urethra, large excretory ducts of some glands, such as esophageal glands, small areas in anal mucous membrane, part of conjunctiva of eye
104
what is the function of stratified columnar epithelium?
protection and secretion
105
what is urothelium?
variable appearamce, unique to urinary system
relaxed: rounded and enlarged stratified cuboidal epithelium
stretched: cells become flatter, giving appearance of stratified squamous epithelium
106
why is urothelium only found in urinary system?
urinary bladder must function in both relaxed and stretched way due to holding water
- multiple layers and elasticity make it ideal for lining hollow structures that are subject to expansion from within
107
what is the function of the urothelium?
allows urinary organs to stretch and maintain protective lining while holding variable amounts of fluid without rupturing
108
what is a Papanicolaou test?
pap smear, collection and microscopic examination of epithelial cells that have been scraped off apical surface of a tissue
109
what is a gland?
epithelium that secretes substances into ducts, onto a surface, or eventually into the blood in the absence of ducts
110
what are endocrine glands?
glands that secrete hormones which enter interstitial fluid and then diffuse into bloodstream without flowing through a duct
111
what are some examples of endocrine glands?
pituitary gland, pineal gland, thyroid and parathyroid glands, adrenal glands, pancreas, ovaries, testes, thymus
112
what is the function of endocrine glands?
secrete hormones that regulate many metabolic and physiological activities to maintain homeostasis
113
what are exocrine glands?
glands that secrete products which are released into ducts that empty onto an epithelium that covers or lines a surface, such as skin surface or lumen of hollow organ
114
where can you find exocrine glands?
sweat, oil, and earwax glands of the skin, digestive glands such as salivary glands and pancreas
115
what is the function of exocrine glands?
produce substances such as sweat to help lower body temp
- oil, earwax, saliva, digestive enzymes
116
which glandular secretions have far-reaching effects?
endocrine secretions because they are distributed throughout body by the bloodstream
117
what classifications are there for exocrine glands?
unicellular - goblet cells
multicellular - sweat, oil salivary glands
118
what are the different structural classifications of multicellular exocrine glands?
1. simple tubular
2. simple acinar
3. simple branched tubular
4. simple branched acinar
5. compound tubular
6. compound acinar
7. compound tubuloacinar
119
what are simple glands?
duct of the gland does not branch
120
what are compound glands?
duct of the gland branches
121
what are merocrine glands?
glands where secretions are released from cells in secretory vesicles via exocytosis
ex; most glands in body, salivary glands, pancreas
122
what are apocrine glands?
glands where secretions accumulate at the apical surface of secreting cell then that portion of cell pinches off by exocytosis from the rest of the cell
ex; milk fats in mammary glands
123
what are holocrine glands?
glands where secretions accumulate in cytosol of secretory cell, and as cell matures, it ruptures and becomes the secretory product
ex; sebaceous gland of the skin
124
what are the different functional classifications of exocrine glands?
merocrine glands, apocrine glands, holocrine glands
125
what two elements compose connective tissue?
extracellular matrix and cells
126
what is the extracellular matrix?
the material located between a connective tissue's cells
- consists of protein fibers and ground substance
127
what are connective tissues that are not highly vascular?
tendons, cartilage, ligaments
128
what cells give rise to the cells of connective tissue?
mesenchymal cells
129
what immature class of cells do each major type of connective tissue contain?
- blast, they retain the capacity for cell division and secrete the extracellular matrix characteristic of that tissue
130
what are fibroblasts?
large flat cells with branching processes, present in all general connective tissues and are usually the most numerous
- secretes fibers and ground substance
131
what are macrophages?
phagocytes that develop from monocytes, WBCs
- destroys bacteria and cell debris
132
what are plasmocytes?
cells that develop from B lymphocytes
- secretes antibodies that attack and neutralize foreign substances
133
what are reticular fibres?
made of collagen and glycoproteins
- provide support in blood vessel walls and form branching networks around various cells
134
what are collagen fibres?
strong, flexible bundles of collagen, most abundant protein in body
135
what are elastic fibres?
stretchable yet strong fibers made of elastin and fibrillin, found in skin, blood vessels, and lung tissue
- smaller in diameter than collagen fibres
- forms fibrous network within connective tissues
136
what are mast cells?
abundant along blood vessels, produce histamine which dilates small blood vessels during inflammation and kills bacteria
137
what are neutrophils?
white blood cells that migrate to sites of infection that destroy microbes by phagocytosis
138
what are eosinophils?
white blood cells that migrate to sites of parasitic infection and allergic responses
139
what are adipocytes?
fat cells that store fats
140
what is ground substance?
material between cells and fibers, supports and binds them together
- made of water, hyaluronic acid, chondroitin sulfate, glucosamine
- provides a medium for exchanging substances between blood vessels and cells
141
what are glycosaminoglycans?
complex combinations of polysaccharides and proteins in ground substance
- associated with proteins called proteoglycanss
142
what is an important property of glycosaminoglycans?
they trap water, making ground substance more jellylike
143
what is hyaluronic acid?
viscous, slippery substance that binds cells together, lubricates joints, and helps maintain the shape of eyeballs
144
why do white blood cells have the ability to produce hyaluronidase?
helps white blood cells move more easily through connective tissue to reach sites of infection
145
what is chondroitin sulfate?
provides support and adhesiveness in cartilage, bone, skin, and blood vessels
146
what are adhesion proteins?
proteins responsible for linking components of the ground substance to one another and to the surfaces of cells
147
what is fibronectin?
main adhesion protein of connective tissues, binds to both collagen fibers and ground substance, linking them together, also attaches cells to ground substance
148
why do collagen fibers often occur in parallel bundles?
bundle arrangement adds great tensile strength to the tissue
149
what is sprain?
stretch or torn ligament due to them being stressed beyond normal capacity
- healing process is slow because of the poor blood supply
150
what is mesenchyme?
embryonic connective tissue that has irregularly shaped mesenchymal cells embedded in semifluid ground substance that contains delicate reticular fibres
151
where can you find mesenchyme?
almost exclusively under skin and along developing bones of embryo,
- some in adult connective tissue especially along blood vessels
152
what is the function of mesenchyme?
forms almost all other types of connective tissue
153
what is mucoid connective tissue?
embryonic connective tissue that was widely scattered fibroblasts embedded in viscous, jellylike ground substance that contains fine collagen fibers
154
where can you find mucoid connective tissue?
umbilical cord of fetus
155
what is the function of mucoid connective tissue?
support
- has possibility of undergoing differentiation
156
what is areolar connective tissue?
mature connective tissue: connective tissue proper: loose connective tissue
- most widely distributed connective tissues
- "packing material of the body"
- consists of fibers arranged randomly and several kinds of cells embedded in semifluid ground substance
157
where can you find areolar connective tissue?
in and around nearly every body structure
158
what is the function of areolar connective tissue?
strength, elasticity, support
159
what is adipose tissue?
mature connective tissue: connective tissue proper: loose connective tissue
- adipocytes derived from fibroblasts are specialized in triglyceride storage as a large, centrally located droplet
160
why do obese people have higher blood pressure than lean people? explain in the context of adipose tissue
with weight gain, adipose tissue increase and new blood vessels form
- obese people have more blood vessels than a lean person
- heart of obese people have to work harder, causing increase in blood pressure
161
what is the function of adipose tissue?
- reduces heat loss through skin
- serves as energy reserve
- supports and protects organs
- excellent source of stem cells
162
where can you find adipose tissue?
wherever areolar connective tissue is located
- subcutaneous tissue deep to the skin
- around heart and kidneys
- yellow bone marrow
- padding around joints
163
what is reticular connective tissue?
mature connective tissue: connective tissue proper: loose connective tissue
- fine interlacing network of reticular fibres and reticular cells
164
where can you find reticular connective tissue?
- stroma/supporting network of liver, spleen lymph nodes
- red bone marrow
- reticular lamina of basement membrane
- around blood vessels and muscles
165
what is the function of reticular connective tissue?
- forms stroma/supporting network of organs
- binds smooth muscle tissue cells
- filters and removes worn-out blood cells in spleen and microbes in lymph nodes
166
what is dense regular connective tissue?
mature connective tissue: connective tissue proper: dense connective tissue
- forms shiny white extracellular matrix, mainly collagen fibres regularly arranged in bundles with fibroblasts in rows between them
- collagen fibres secreted by fibroblasts are not living, so damaged tendons and ligaments heal slowly
167
what is the function of dense regular connective tissue?
forms tendons which attach muscle to bone
ligaments which attach bone to bone
and aponeuroses which attach muscle to muscle or bone to bone
168
what is the function of dense regular connective tissue?
- provides strong attachment between various structures
- withstands pulling/tension along long axis of fibres
169
what is dense irregular connective tissue?
mature connective tissue: connective tissue proper: loose connective tissue
- made up of collagen fibres, usually irregularly arranged with a few fibroblasts
170
what is the function of dense irregular connective tissue?
provides tensile strength in many directions due to irregular arrangement
171
what is elastic connective tissue?
mature connective tissue: connective tissue proper: loose connective tissue
- contains predominantly elastic fibres with fibroblasts between them
- unstained tissue is yellowish
172
where can you find elastic connective tissue?
- walls of elastic arteries and trachea
- bronchial tubes within the lungs
- true vocal cords
- suspensory ligaments of penis,
- some ligaments between vertebrae
173
what is the function of elastic connective tissue?
allows stretching of various organs
- strong and can recoil to original shape after being stretched
- important to normal functioning of lung tissues which recoil in exhaling and elastic arteries which recoil between heartbeats to help maintain blood flow
174
what is cartilage?
dense network of collagen/elastic fibres firmly embedded in chondroitin sulfate, a gel-like component of ground substance
- can endure more strain than loose and dense connective tissue
- strength is due to collagen fibres
- resilience/ability to assume original shape after deformation is due to chondroitin sulfate
175
why does cartilage not have a blood supply?
cartilage secrets antiangiogenesis factors
176
what are chondrocytes?
mature cartilage cells
177
what is cartilage lacunae?
spaces within extracellular matrix of cartilage
178
what is perichondrium?
- covering of dense irregular connective tissue
- surrounds the surface of most cartilage
- contains blood vessels and nerves
- source of new cartilage cells
179
why does cartilage heal poorly after an injury?
- cartilage has no blood supply
- relatively metabolically inactive
180
how does cartilage play an important role as a support tissue in the body?
- resists tension (stretching), compression (squeezing), and shear (pushing in opposite directions)
- resilient
- strong and firm
- precursor to bone, forming almost the entire embryonic skeleton
181
what is hyaline cartilage?
mature connective tissue: supporting connective tissue: cartilage
- contains resilient gel as ground substance and appears in body is bluish-white, shiny substance
- prominent chondrocytes found in cartilage lacunae
- surrounded by perichondrium
- weakest type of cartilage and can be fractured
182
where can you find hyaline cartilage?
most abundant cartialge in body
- ends of long bones
- anterior ends of ribs
- nose
- parts of larynx, trachea, bronchi, bronchial tubes
- embryonic and fetal skeleton
183
what is the function of hyaline cartilage?
provides smooth surfaces for movement at joints, flexibility, and support
184
what is fibrous cartilage?
mature connective tissue: supporting connective tissue: cartilage
- has chondrocytes among clearly visible thick bundles of collagen fibers within extracellular matrix
- lacks perichondrium
185
where can you find fibrous cartilage?
- pubic symphysis, where hip bones join anteriorly
- intervertebral disks
- menisci of knee
- portions of tendons that insert into cartilage
186
what is the function of fibrous cartilage?
- support and joining structures together
- strength and rigidity make it strongest type of cartilage
187
what is elastic cartilage?
mature connective tissue: supporting connective tissue: cartilage
- has chondrocytes in threadlike network of elastic fibres within extracellular matrix
- perichondrium present
188
where can you find elastic cartilage?
- lid on top of larynx/epiglottis
- part of external ear
- auditory tubes
189
what is the function of elastic cartilage?
- provides strength and elasticity
- maintains shape of certain structures
190
what happens in interstitial growth of cartilage?
- growth from within tissue
- cartilage increases rapidly in size due to division of existing chondrocytes and continuous deposition of increasing amounts of extracellular matrix by chondrocytes
- occurs when cartilage is young and pliable, during childhood and adolescence
191
what happens in appositional growth of cartilage?
- growth at outer surface of tissue
- cells in inner cellular layer of perichondrium differentiate into chondroblasts
- chondroblasts surround themselves with extracellular matrix and become chondrocytes
- matrix accumulates beneath perichondrium on outer surface of cartilage, causing it to grow in width
occurs later than interstitial growth and continues through adolescence
192
what is compact bone tissue?
mature connective tissue: supporting connective tissue: bone tissue
- consists of osteons that contain bone lamellae, bone lacunae, bone canaliculi, osteocytes, and osteonic canals
193
what is spongy bone tissue?
mature connective tissue: supporting connective tissue: bone tissue
- consists of thin columns of bane trabeculae
- spaces between bone trabeculae are filled with red bone marrow
194
where can you find bone tissue?
both compact and spongy bone tissue make up bones of the body
195
what is the function of bone tissue?
- support
- protection
- storage
- houses blood forming tissue
- serves as levers that act with muscle tissue to enable movement
196
what is an osteon?
the basic unit of structure in adult compact bones
- consists of a central canal, bone lamellae, bone lacunae, bone canaliculi, osteocytes
also called haversian system
197
what are the bone lamellae?
little plates, concentric rings of extracellular matrix
- consist of mineral salts (mostly calcium and phosphate) which give bone its hardness and compressive strength
- consist of collagen fibers which give bone its tensile strength
- responsible for the compact nature of compact bone tissue
198
what are the bone lacunae?
small spaces between bone lamellae that contain mature osteocytes
199
what are the bone canaliculi?
projecting from bone lacunae
- networks of small canals containing the processes of osteocytes
- provides routes for nutrients to reach osteocytes and for wastes to leave them
200
what is the osteonic canal?
the central canal of compact bones containing blood vessels and nerves
201
Instead of osteons/haversian systems, what do spongy bone tissues have?
they have trabeculae, columns of bone which contain bone lamellae, bone lacunae, bone canaliculi, and osteocytes
- spaces between bone trabeculae are filled with red bone marrow
202
what is blood?
mature connective tissue: liquid connective tissue: blood
- consists of blood plasma and formed elements:
- RBCs (erythrocytes)
- WBCs (leukocytes)
- platelets (thrombocytes)
203
what is the function of blood?
RBCs: transport oxygen and CO2
WBCs: carry on phagocytosis and mediate allergic rxns and immune system responses
platelets: blood clotting
204
what is lymph plasma?
mature connective tissue: liquid connective tissue: lymph plasma
- flows in lymphatic vessels
- consists of several types in a clear liquid extracellular matrix but w/ less proteins than that of blood plasma
205
what is a membrane?
flat sheet of pliable tissue that covers or lines a part of the body
206
what are the different types of epithelial membranes?
1. mucous membrane
2. serous membranes
3. cutaneous membranes/skin
207
what are mucous membranes?
membranes that line a body cavity which open directly to the exterior
- consists of a lining layer of epithelium and an underlying layer of connective tissue
- lines entire digestive canal, respiratory, and genital tracts
- contain goblet cells
208
what is an important feature of the epithelial layer of mucous membranes?
acts as barrier that microbes and other pathogens have difficulty penetrating
- tight junctions usually connect these cells, so materials cannot leak between them
- goblet cells secret mucous which prevents cavities from drying out
209
what kind of connective tissue is found in mucous membranes?
alveolar connective tissue called the laminar propria
210
what is the laminar propria?
alveolar connective tissue layer of mucous membranes
- supports epithelium
- binds epithelium to underlying structures
- allows some flexibility of the membrane
- affords some protection for underlying structures
- holds blood vessels in place
- vascular source for overlying epithelium
- oxygen and nutrients diffuse from lamina propria to the covering epithelium and wastes diffuse in opposite direction
211
what are serous membranes?
membranes that line body cavities that do not open directly to the exterior (thoracic or abdominal cavities)
- have visceral and parietal layers
- mesothelium of serous membranes secrete serous fluid allowing organs to glide easily over one another
212
what are cutaneous membranes?
membrane that covers entire surface of body
- consists of a superficial portion = epidermis
- consists of a deeper portion = dermis
213
what does the epidermis consist of?
- keratinized stratified squamous epithelium
- protects underlying tissues
214
what does the dermis consist of?
- dense irregular connective tissue and areolar connective tissue
215
what are synovial membranes?
membranes that line the cavities of partially to freely movable joints
- line structures that do not open to exterior
- lack an epithelium and are not epithelial membranes
- composed of discontinuous layer of synoviocytes close to articular cavity (space btwn bones
- composed of layer of areolar/adipose connective tissue deep to the synoviocytes
- synoviocytes secrete synovial fluid
216
what is synovial fluid?
- lubricates and nourishes cartilage covering the bones at movable joints
- contains macrophages that remove microbes and debris from joint cavity
217
what are muscular tissues?
tissues consisting of elongated muscle fibers/myocytes that use ATP to generate force
- produces body movements, maintains posture, generates heat
- provides protection
218
what are the three types of muscular tissues?
1. skeletal
2. cardiac
3. smooth
219
what are skeletal muscle tissues?
muscular tissues that consist of long, cylindrical, striated fibers
- vary in length
- voluntary, made to contract or relax with conscious control
220
what are muscle fibers?
muscle fibers are roughly cylindrical, multinucleated cell with nuclei at periphery
221
what is the function of skeletal muscle tissues?
motion, posture, heat production, protection
222
what are cardiac muscle tissues?
muscular tissues that consist of branched, striated fibers
- usually only one centrally located nucleus, max two
- have intercalated discs
- involuntary control
223
what are intercalated disks?
transverse thickenings of plasma membrane
- contains desmosomes which strengthen tissue and holds fibres together during vigorous contractions
- contains gap junctions for quick conduction of electrical signals/muscle action potentials throughout heart
224
what is the function of cardiac muscle tissues?
pumps blood to all parts of the body
225
what are smooth muscle tissues?
muscular tissues that consist of NONstriated fibres
- gap junctions connect many individual fibres in some smooth muscle tissue
- involuntary control
- produces powerful contractions as many muscle fibers contract in unison
- where no gap junctions, smooth muscle fibers contract individually like skeletal muscle fibres
226
what are smooth muscle fibres?
small spindle-shaped cells thickest in the middle, tapering at each end, and containing a single, centrally located nucleus
227
what is the function of smooth muscle tissues?
motion
- constriction/dilation of blood vessels
- peristalsis
228
what are the two principal types of cells in nervous tissue?
neurons and neuroglial cells
229
what are neurons?
nerve cells sensitive to various stimuli
- converts stimuli to electrical signals - nerve action potentials
- conducts action potentials to other neurons
- consists of dendrites, cell body, axons
230
what are neuroglial cells?
nerve cells that do not generate or conduct nerve impulses, but support and protect neurons
231
what is electrical excitability?
the ability to respond to certain stimuli by producing electrical signals such as action potentials which propagate through plasma membrane of neurons/muscle fibers due to the presence of specific voltage-gated ion channels
232
what are neurotransmitters?
chemicals released by neurons after an action potential forms in the neuron
- allows neurons to communicate with other neurons, muscle fibers, or glands
233
the restoration of an injured tissue or organ to normal structure or function depends entirely on what?
depends entirely on whether parenchymal cells are active in the repair process
234
what is fibrosis?
the process by which fibroblasts synthesize collagen fibers and other extracellular matrix materials that aggregate to form scar tissue
235
does fibrosis allow an injured or damaged tissue/organ to normal structure/function?
No, because scar tissue formed from fibrosis is not specialized to perform the functions of the parenchymal tissues
236
what is granulation tissue?
new tissue formed across a wound or surgical incision to provide a framework that supports the epithelial cells that migrate into open area and fill it
- formed because both connective tissue stroma and parenchymal cells are active in repair
- secretes fluid that kills bacteria
237
what three factors impact tissue repair?
nutrition, blood circulation, age
238
Why does a cut on your shin not heal and bleeds easily, if you have been on a bread-and-water diet for 3 weeks?
does not provide necessary nutrients to encourage tissue repair
- no proteins or vitamins
239
what is the benefit of baby fat?
baby fat is mainly brown fat-highly vascularized and many mitochondria
- brown fat produces heat which helps maintain infant's body temp
240
what are some adaptations you can incorporate into the structure/amount of tissues an individual has so the individual can survive on a large planet with a cold dry climate and a thin atmosphere?
- more adipose tissue for insulation
- thicker bones for support
- more RBCs for O2 transport
- Increased thickness of skin to prevent water loss
