1
Q
what are tissues?
A
groups of similar cells that work together to carry out a specialized function
2
Q
what are various tissue types organized into to perform specific body functions?
A
organized into organs, arrangement of tissues in an organ determines the organ’s structure and function
3
Q
how do you see the details of finer structures like cilia and cell membranes under light microscopes?
A
under high power, rotate the fine focus knob back and forth an eighth of a turn to see the details
4
Q
where can you find epithelial tissues?
A
- lines cavities and hollow organs
- forms glands
- covers external body surfaces
5
Q
what is the function of epithelial tissues?
A
- protection
- secretion
- absorption
- filtration
- excretion
6
Q
what are some characteristics of epithelial tissues?
A
- avascular, gets nutrients by diffusion from blood vessels located in underlying connective tissue
- basal surface attached to basement membrane
- apical surface are exposed to lumen
- may produce specialized secretions
- cells can regenerate by mitosis
7
Q
what is simple squamous epithelium?
A
single layer of flattened cells with a central nucleus
8
Q
where can you find simple squamous epithelium?
A
- lines blood and lymphatic vessels, alveoli, glomerular capsule, inner surface of tympanic membrane
- forms serous membranes
9
Q
what is the function of simple squamous epithelium?
A
- thinness allows passage of materials by diffusion and filtration in areas where protection not important
- secretes serous fluid within serous membranes
10
Q
what is simple cuboidal epithelium?
A
a single layer of cube-shaped cells with a large, central nucleus
11
Q
where can you find simple cuboidal epithelium?
A
- makes up secreting portions of some glands (thyroid)
- ducts of some glands (pancreas)
- ovary surface
- kidney tubules
12
Q
what is the function of simple cuboidal epithelium?
A
absorption and secretion
13
Q
what is simple columnar epithelium?
A
single layer of cells which are taller than they are wide
- oval-shaped nucleus found in lower half of cell
- goblet cells and maybe microvilli
14
Q
where can you find simple columnar epithelium?
A
- nonciliated version lines digestive canal, gallbladder
- ciliated version lines bronchioles of respiratory tract
15
Q
what is the function of simple columnar epithelium?
A
- secretion and absorption
- goblet cells secret mucus which lubricate linings of digestive and respiratory tract
- if present, cilia move fluids across cell surfaces
16
Q
what is pseudostratified columnar epithelium?
A
as in simple ciliated columnar, not all cells reach lumen but all are attached to basement membrane
- goblet cells and cilia may be present
17
Q
where can you find pseudostratified columnar epithelium?
A
lines airways of most of upper respiratory tract
18
Q
what is the function of pseudostratified columnar epithelium?
A
- secrets mucus which trap foreign particles
- cilia sweep and move mucus and foreign particles away for elimination from body
19
Q
what is stratified squamous epithelium?
A
several layers of cells
squamous shaped cells near apical surface and cuboidal or columnar shaped cells near basal surface
20
Q
where can you find stratified squamous epithelium?
A
nonkeratinized: wet surfaces, such as lining of mouth, vagina
keratinized: skin
21
Q
what is the function of stratified squamous epithelium?
A
- protection against abrasion, water loss, UV radiation, foreign invasion
- 1st line of defense against microbes
22
Q
what is urothelium?
A
when relaxed, cells at apical surface look large and rounded, not all cells reach apical or basal surface, cells can be variety of shape and size
23
Q
where can you find urothelium?
A
exclusive to urinary system
- ureter and bladder
24
Q
what is the function of urothelium?
A
- allows urinary organs to stretch and maintain protective lining while holding variable amounts of fluid without rupturing
- multiple layers and elasticity make it ideal for lining hollow structures subjected to expansion from within
25
compare the functions of simple epithelium with that of stratified epithelium
simple - absorption and secretion
stratified - protection and barrier
26
what are the two types of epithelial tissues that have goblet cells?
simple columnar epithelium and pseudostratified columnar epithelium
27
what are endocrine glands?
glands that produce secretions which are released into the surrounding interstitial tissue and distributed by the blood stream
28
what are exocrine glands?
glands that produce secretions which are released via ducts onto an epithelial surface
29
what are acini?
darker purple clusters of cells which make up majority of pancreas, secrete pancreatic juice
30
what is the pancreas?
exocrine cells secrete buffers and digestive enzymes, contain islets and acini
31
what are salivary glands?
exocrine glands associated with oral cavity prominent ducts with visible lumen and acini
32
where can you find salivary glands?
mouth, oral cavity
33
what is the function of salivary glands?
- secretes saliva containing substances to lubricate food, adhere together chewed pieces into bolus, and begin process of chemical digestion
34
what are sudoriferous glands?
coiled, tubular glands located in deep dermis or upper subcutaneous
- lumen can be seen in coiled regions, rarely seen leading to the surface
35
what is the function of sudoriferous glands?
- regulates body temp
- waste removal
- stimulated during emotional stress
36
what are sebaceous glands?
located behind hair follicles in dermis and epidermis, acinar cells are tear drop in shape, lumen very narrow
37
what is the function of sebaceous glands?
- prevents hair from drying out
- prevents water loss
- makes skin soft
- inhibits bacterial growth
38
what are the most common functions of connective tissues?
- protection
- support
- binds together other tissues
- insulation
- transportation
- adipose tissue store fat for energy
39
what are the two components of the extracellular matrix?
- ground substance that may be fluid, semifluid, gelatinous, very hard
- combo of collagen, reticular, or elastic fibres which strengthen and support connective tissue
40
what are the characteristics of connective tissue?
- has vast extracellular matrix
- many types of cells and fibres scattered throughout tissue
- highly vascularized except cartilage, tendons, ligaments
41
what are collagen fibres?
fibres made of collagen, most abundant protein in body
- often occur in parallel bundles
- adds strength but not stiffness
- found in cartilage, bone, tendons, ligaments
42
what are elastic fibres?
- strong, stretchable fibres that can be stretched up to 150x their relaxed length without breaking
- found in skin, blood vessel walls, lungs
- made of elastin and fibrillin
43
what are reticular fibres?
fibres made of glycoproteins and collagen
- forms branching networks, providing support and strength
- forms the framework for many soft organs like spleen, lymph nodes
- forms part of basement membranes of epithelial tissues
- provides support in blood vessel walls
44
what are fibroblasts?
immature, large, flat cells that move through connective tissue and secretes fibres and ground substance
45
what are macrophages?
cells that develop from monocytes and destroy bacteria and cell debris by phagocytosis
46
what are mast cells?
cells most abundant along blood vessels
- produce histamine which dilate blood vessels during inflammation and kills bacteria
47
what are plasma cells?
cells that develop from B lymphocytes
- secrete antibodies that attack and neutralize foreign substances
48
what are adipocytes?
fat cells that store fats
- found below skin and around organs like the heart and kidney
49
what are neutrophils?
white blood cells that migrate to sites of infection and destroy microbes by phagocytosis
50
what are eosinophils?
white blood cells that migrate to sites of parasitic infection and allergic responses?
51
what is ground substance?
material between cells and fibres in connective tissue
- made of water, hyaluronic acid, chondroitin sulfate, glucosamine
- supports cells and fibres, binds them together
- provides medium for exchanging substances between blood and cells
52
what is areolar connective tissue?
has all three types of fibers and many different types of cells with a loose, irregular arrangement
53
where can you find areolar connective tissue?
- in and around nearly every body structure
- dermis
- subcutaneous layer
- lamina propria of mucous membranes
- surrounds blood vessels, nerves, body organs
54
what is the purpose of areolar connective tissue?
- strength
- elasticity
- support
55
what is adipose connective tissue?
nucleus and cytoplasm are displaced peripherally due to a large internal fat droplet
- matrix sparse and cells are closely packed
56
where can you find adipose connective tissue?
wherever areolar connective tissue is located
- subcutaneous layer deep to the skin
- yellow bone marrow
- around heart and kidneys
57
what is the function of adipose connective tissue?
- reduces heat loss through skin
- energy reserve
- supports and protects organs
- excellent source for stem cells
58
what is reticular connective tissue?
a network of dark reticular fibres with many cells containing small, round nuclei
59
where can you find reticular connective tissue?
- red bone marrow
- forms framework of liver, spleen, lymph nodes
- reticular lamina of basement membrane
- around blood vessels and muscles
60
what is the function of reticular connective tissue?
- forms framework of organs
- binds smooth muscle tissue cells
- removes worn-out blood cells in spleen and microbes in lymph nodes
61
what is dense regular connective tissue?
wavy bundles of parallel collagen fibres, darkly stained nuclei between the collagen fibres
62
where can you find dense regular connective tissue?
- forms tendons, most ligaments, and aponeuroses
63
what is the function of dense regular connective tissue?
- provides strong attachment between structures
- withstands pulling/tension along long axis of fibres
64
what is hyaline cartilage?
sparse numbers of chondrocytes lie in lacunae
- matrix is made up of fine collagen fibres that are not visible
- most abundant, weakest cartilage in body
65
where can you find hyaline cartilage?
- at ends of long bones
- anterior ends of ribs
- nose
- parts of larynx
- trachea
- bronchi
- bronchial tubes
- embryonic and fetal skeleton
66
what is the function of hyaline cartilage?
- provides smooth movement at joints
- flexibility
- support
67
what are lacunae?
small cavities in bone and cartilage which hold chondrocytes (in cartilage) and osteocytes (in bone)
68
what are chondrocytes?
cells that secret extracellular matrix for cartilage, embedded in them
69
what is bone connective tissue?
matrix of collagen fibers and mineral salts (mainly calcium and phosphate) are organized into lamellae
- osteocytes sit in bone lacunae and are connected by bone canaliculi
70
what is the function of bone connective tissue?
- support
- protection
- houses blood-forming tissues
- serves as levers that act with muscle tissue to enable movement
71
what is blood connective tissue?
cells found in blood plasma/fluid extracellular matrix
- fibres observed only during clotting
- erythrocytes, leukocytes, and thrombocytes
72
what is the function of blood connective tissue?
delivers nutrients and oxygen to all parts of the body and gets rid of waste from them
73
what are muscle tissues?
tissues that contract to provide body movements, to pump blood, to control movement of materials through the viscera
74
what is skeletal muscle tissue?
- long, cylindrical, striated, multinucleated muscle fibres
- nuclei on periphery of cells
- voluntary
75
where can you find skeletal muscle tissue?
attached to bones by tendons
76
what is the function of skeletal muscle tissue?
- motion
- posture
- heat production
- protection
77
what is cardiac muscle tissue?
short, branched cells that typically only have one nucleus located at centre
- have intercalated discs and striations
- involuntary
78
what are intercalated discs?
structures in muscle cells that connect heart tissue to ensure smooth and rapid contraction, has gap junctions
79
what is the function of cardiac muscle cells?
- pumps blood to all parts of body via involuntary contractions
80
what is smooth muscle tissue?
short, spindle-shaped cells with a single centrally located nucleus
- involuntary
- no intercalated discs or striations
81
where can you find smooth muscle tissue?
- iris of eyes
- walls of hollow internal structures of organs
- blood vessels
- airways
82
what is the function of smooth muscle tissue?
- functions in motion/constriction/dilation of blood vessels and airways
- propulsion of food through digestive tract
- contraction of urinary bladder and gallbladder
83
what is nervous tissue?
tissue composed of neurons and neuroglial cells
- convert chemical or mechanical stimuli into action potentials/nerve impulses
84
what do neuroglial cells do?
supporting cells that insulate, support, and protect neurons
much smaller and numerous than neurons
85
what is the integumentary system?
a body system consisting of the skin and accessory structures such as glands, nails, hair, muscles, nerves
86
what is the integumentary system involved in?
protection against mechanical stress, regulates water and heat loss, site of vit D synthesis
87
what are the two distinct regions of the integument?
- epidermis and dermis
88
what is the epidermis?
superficial layer composed of keratinized stratified squamous epithelium
- protection, water repellent, moderates entry and exit out of cell
89
what is the dermis?
deeper layer composed of connective tissue
90
what layers in the epidermis are present in thick-skinned areas such as the palmar and plantar surfaces?
1. stratum corneum
2. stratum lucidum (not in thin-skinned areas)
3. stratum granulosum
4. stratum spinosum
5. stratum basale
91
what are dermal papillae?
finger-like projections in dermis which attach it to the epidermis
92
which one is vascularized: epidermis or dermis?
dermis
93
what attaches the dermis to the subcutaneous later?
numerous collagen and elastic fibres
94
what are cutaneous sensory receptors?
sensory receptors found in the dermis
- when stimulated by environmental changes, they transmit messages to the brain(CNS) for interpretation
95
what is the hypodermis?
attaches dermis to the underlying structures
- composed mainly of adipose tissues and areolar tissues
- contains large blood vessels that supply the dermis w nutrients and stores fat
96
what causes hairs to stand upright?
arrector muscles of the hair (arrector pili muscles) which are attached to hair follicles
97
what is the stratum corneum?
outermost layer, undergoes exfoliation
98
what is the function of stratum corneum?
protects deeper layers from injury and microbial invasion
99
what is the stratum lucidum?
present in thick skin, 4-6 layers of keratinized skin
100
what is the function of stratum lucidum?
additional level of toughness for thick skin
101
what is the stratum granulosum?
middle layer, undergoes apoptosis
102
what is the function of stratum granulosum?
cells here die to form outer layers, provides waterproof barrier
103
what is the stratum spinosum?
superficial to stratum basale, coarser bundles of keratin that join at desmosomes
104
what is the function of stratum spinosum?
provides strength and flexibility to skin
105
what is the stratum basale?
next to basement membrane, single layer of cuboidal or columnar cells
106
what is the function of stratum basale?
protection from injury, forms new cells from stem cells
107
what is the dermal papillae?
small, nipple-shaped structures that project into undersurface of epidermis
108
what is the function of the dermal papillae?
increases SA for increased absorption
109
what is the tactile corpuscle/Meissner corpuscle?
in dermal papilla of hairless skin; nerve endings sensitive to touch/tactile receptors
110
what is the function of the tactile corpuscle/Meissner corpuscle?
detect the onset of the sensation of touch and low frequency vibration
111
what is the lamellar corpuscle/Pacinian corpuscle?
in dermis and subcutaneous layer; sensory & tactile receptors
112
what is the function of the lamellar corpuscle/Pacinian corpuscle?
detects high frequency vibrations
113
what is the subcutaneous layer?
deep to dermis, not part of skin; consists of areolar & adipose tissues;
114
what is the function of the subcutaneous layer?
storage depot for fat & contains large blood vessels that supply the skin
115
what is the hair follicle?
in the dermis layer, surrounds the root of a hair; grows hair by packing cells together; anchor hair to skin
116
what is hair?
keratinized stratified squamous epithelium; regulates temp, sensory organ
117
what is the arrector pili muscle?
small muscles attached to hair follicle; sensory receptor that contracts
118
what are eccrine sudoriferous glands?
skin of most regions and tubular glands
119
what is the function of eccrine sudoriferous glands?
- regulation of temperature
- waste removal
- stimulated during emotional stress
120
what are apocrine sudoriferous glands?
sudoriferous glands found in axillary and genital areas
121
what is the function of apocrine sudoriferous glands?
secretion of perspiration stimulated during emotional stress and sexual excitement
122
where would you expect to find the thinnest keratinized epidermis?
eyelids
123
what are the functions of keratinocytes?
- produce keratin
- protection against external environment
124
what is the function of the capillary networks in the dermis?
125
what type of muscle tissue are the arrector pili muscles made of?
126
what regions of the body do not have hair?
127
what are melanocytes?
cells that produce melanin
128
what is melanin?
pigment that gives skin colour
129
where are melanocytes located?
in the stratum basale
130
which layers of the epidermis have accumulations of melanin in their cells?
131
what is the function of melanin in the skin?
- protection against UV radiation
132
what is the origin and function of carotene in the stratum corneum?
