intro to histology Flashcards

1
Q

why is histology important?

A
  • provides structural basis for gross anatomy (and many of the life sciences)
  • essential for understanding function and pathological change
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2
Q

what are the 4 categories of tissues recognized in histology?

A
  1. epithelial tissue
  2. connective tissue
  3. muscular tissue
  4. nervous tissue
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3
Q

what are the general functions of each of the 4 tissue categories?

A
  1. surface and glandular (epithelium)
  2. support (connective)
  3. contraction (muscular)
  4. innervation (nervous)
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4
Q

what is the structure of epithelial tissue?

A

cohesive sheets of cells

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5
Q

what are the specialized functions of epithelium?

A
  • barrier between the internal and external environment
  • mechanical protection
  • absorption and secretion
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6
Q

what are the subdivisions of epithelial tissue?

A
  • surface epithelium
  • glandular epithelium
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7
Q

list the 3 factors that mediate the epithelial tissue functions

A
  • structural modifications to the surface (microvilli, cilia)
  • internal modifications (associated with manufacture of secretions and secretion)
  • special types of junctional complexes between cells
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8
Q

what are cell-cell junctional complexes and what is their function?

A

they determine how and what can pass between cells
- function to link cells together but can also have functional implications

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9
Q

what are the 3 types of cell-cell junctional complexes?

A
  1. occluding (tight) junctions
  2. anchoring (adhering) junctions
  3. communicating (gap) junctions

all 3 are present in but varying amounts depending on the type of epithelium

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10
Q

what is the function of a tight junction?

A

to prevent diffusion of molecules between adjacent cells
- form a variously permeable barrier

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11
Q

what is the function of adhering junctions?

A

link cells together and provide mechanical strength

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12
Q

list some examples of adhering junctions

A
  • belt demosomes
  • spot demosomes
  • hemi-demosomes
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13
Q

what is the function of gap junctions?

A

allow movement of molecules between cells

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14
Q

what are the three shapes of epithelial cells?

A
  • squamous
  • columnar
  • cuboidal
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15
Q

what do squamous cells look like?

A

flat and sheet-like in appearance, often described as looking like fish scales
- large cells with small round nuclei

stratified squamous epithelium
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16
Q

what do cuboidal cells look like?

A

cube-like shape (H=W=D) with a central nucleus, looks roughly like dice

cuboidal cells - usually in glands
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17
Q

what do columnar cells look like?

A

tall, rectangular column-like shape with nuclei usually located towards the bottom of the cell

simple columnar epithelium
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18
Q

what are the 3 classification criteria of surface epithelia?

A
  1. number of cell layers (simple or stratified)
  2. shape of surface cells (squamous, cuboidal, or columnar)
  3. surface specializations (keratin, cilia, microvilli)
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19
Q

what are the 3 types of simple epithelium?

A
  1. simple squamous epithelium
  2. simple cuboidal epithelium
  3. simple columnar epithelium
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20
Q

describe what simple squamous epithelium looks like and where is it located in the body?

A
  • single layer of squamous cells
  • functionally suited to surfaces where mechanical protection is not required
  • e.g. lining of blood vessels, inside body cavities
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21
Q

describe what simple cuboidal epithelium looks like and where is it located in the body?

A
  • single layer of cuboidal cells
  • functionally suited to surfaces with an absorptive/secretory role
  • e.g. secretory cells of exocrine glands, kidneys, ovaries
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22
Q

describe what simple columnar epithelium looks like and where is it located in the body?

A
  • single layer of columnar cells
  • functionally suited to surfaces with an absorptive role
  • large surface area due to height of cells and microvilli
  • e.g. digestive tract, uterus, reproductive system
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23
Q

what are the 3 types of stratified epithelium?

A
  • (keratinized) stratified squamous epithelium
  • stratified cuboidal epithelium
  • stratified columnar epithelium
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24
Q

what does (keratinized) stratified squamous epithelium look like and where is it located in the body?

A
  • functionally suited to surfaces where there is a varying amount of mechanical protection required
  • stratified squamous epithelium: layers of squamous cells; living nucleated cells which flatten towards the surface
  • e.g. skin, pharynx, esophagus
  • keratinized stratified epithelium: live cells underneath layer(s) of flattened, dead, keratinized cells on the surface
  • e.g. paw pads, tongue
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25
Q

what does stratified cuboidal/columnar epithelium look like and where is it located in the body?

A
  • functionally usually associated with ducts (of glandular epithelium)

cuboidal: many layers of cuboidal cells
- e.g. sweat glands, mammary glands, salivary glands

columnar: many layers of columnar cells
- conjunctiva, pharynx

26
Q

what are the 2 types of special surface epithelium?

A
  • transitional epithelium (urothelium)
  • pseudostratified cilliated columnar epithelium with goblet cells

appear to be stratified but all cells are in contact with the basement membrane

27
Q

what does transitional epithelium (urothelium) look like and where is it located in the body?

A
  • large ovoid surface cells
  • functionally suited to surfaces which are required to stretch
  • e.g. urinary bladder
28
Q

what does pseudostratified ciliated columnar epithelium with goblet cells look like and where is it located in the body?

A
  • one layer of columnar cells (nuclei at varying levels) with goblet cells and cilia
  • functionally suited to surfaces involved in cleansing (cilia) and moistening
  • e.g. upper and lower portions of the respiratory system, trachea
29
Q

what are 2 important structures in glandular epithalial tissue?

A
  1. goblet cells
    - single cells that retain connection with surface epithelial cells
  2. secretory cells
    - embedded in the underlying connective tissue
30
Q

describe the structure of exocrine glands

A
  • glandular epithelium with a duct to the surface
  • widely distributed throughout the body systems
  • produce mucus and serous secretions
31
Q
A
32
Q

describe the structure of endocrine glands

A
  • glandular epithelium without a duct
  • localized
  • highly specialized functions
33
Q

what shade of stain do serous secretory cells uptake?

A

dark stain

34
Q

what shade of stain do mucus secretory cells uptake?

A

pale stain

35
Q

what shade of stain do sero-mucus secretions uptake?

A

mix of pale and dark stain

36
Q
A
37
Q

what are the 4 classifications of connective tissue related to function?

A
  1. embryonic connective tissue
  2. general adult connective tissue
  3. adipose tissue
  4. special supportive connective tissue
38
Q

what are the subtypes of general adult connective tissue?

A
  1. loose
  2. dense
  3. regular
  4. irregular
39
Q

what is the function of general adult connective tissue?

A

support and connection between different tissues

40
Q

what is the function of adipose tissue?

A

provides protection, insulation, and energy reserve

41
Q

what are the subtypes of special supportive connective tissue?

A
  1. cartilage
  2. blood
  3. bone
42
Q

what is the function of special supportive connective tissue?

A

provides a structural framework; a medium for transport; has a vital role in the healing process

43
Q

what do all connective tissues consist of?

A

resident cells
- mesenchymal cells
- macrophages
- adipocytes
- fibroblasts

extracellular matrix
- protein fibers (elastic, collagen, reticular)
- amorphous ground substance

transient cell population
- plasma cells (antibodies)
- eosinophils (protection)
- neutrophils (protection)
- lymphocytes (protection)

the proportion and type of cells, fibers, and composition of the ground substance varies in different types of connective tissue

44
Q

explain the spaghetti bolognese metaphor for connective tissue

A
  • spaghetti = connective fibers
  • sauce = ground substance
  • meat/veggies = cellular matter
  • the recipe may vary = different proportions of the elements
45
Q

describe the characteristics of loose connective tissue

A
  • more cells than fibers
  • very little support
  • designed for absorption
  • covered in epithelium
  • e.g. villi of small intestine
46
Q

describe the characteristics of dense regular connective tissue

A
  • more fibers than cells
  • fibers are in alignment
  • ribbon-like fibers
  • one directional support (strength in one direction)
  • e.g. tendons
47
Q

describe the characteristics of dense irregular connective tissue

A
  • more fibers than cells
  • fibers arranged in multiple directions (irregular)
  • multi-directional strength
  • cells are usually fibroblasts or fibrocytes
48
Q

describe the cells found in and the function of adipose tissue

A

main cell type:
- adipocyte

function:
- energy store (white fat)
- heat production (brown fat)
- protection

49
Q

describe what adipose tissue looks like

A
  • cytoplasm of each adipocyte is filled with a single lipid droplet
  • nucleus is pushed to the periphery
50
Q

what are the 3 main areas of the body where muscle is found?

A
  • walls of all hollow organs
  • muscles associated with the skeleton
  • heart
51
Q

what are the 3 types of muscle fibers?

A
  • skeletal
  • cardiac
  • smooth
52
Q

which types of muscle fiber are striated?

A
  • skeletal
  • cardiac
53
Q

which muscle types are voluntary and which are involuntary?

A

voluntary:
- skeletal

involuntary:
- skeletal
- cardiac

54
Q

list the key features of skeletal muscle in the transverse section?

A

transverse:
- multiple, peripheral nuclei
- cytoplasm packed full of myofibrils
- branches of connective tissue
- looks like tuna steaks

55
Q

list the key features of skeletal muscle in the longitudinal section?

A
  • peripheral nuclei
  • striated
  • long unbranched fibers
  • limited amount of connective tissue between fibers
56
Q

list the key features of cardiac muscle in the transverse section?

A
  • single central nucleus present in sectioned fibers
  • cross sections of fairly uniform size
  • lots of connective tissue between fibers
57
Q

list the key features of cardiac muscle in the longitudinal section?

A
  • central nucleus
  • striated
  • short branched fibers
  • intercalated discs join fibers (can be seen)
  • abundant connective tissue between fibers
58
Q

list the key features of smooth muscle in the transverse section?

A
  • individual spindle shaped cells
  • cross sections have variable diameter
  • only a few central nuclei (dependent on where the cross section cuts each cell)
  • cells are linked together
59
Q

list the key features of smooth muscle in the longitudinal section?

A
  • central nucleus
  • non-striated
  • short tapering fibers
  • limited connective tissue between fibers
60
Q

list some questions you can ask to distinguish between the 3 muscle types

A
  1. what is the orientation? longitudinal or transverse?
  2. if the orientation is longitudinal, is the muscle striated?
  3. do the muscle fibers consist of single cells or a single cell with multiple nuclei (which function as a coordinated unit)?
  4. is there a single central nucleus or multiple nuclei at the periphery?
  5. can you see any special types of cell-cell junctional complexes?
  6. is the section from an area where you would expect voluntary or involuntary control/contraction of muscle fibers?
61
Q

what do the neurons, glanglions, and peripheral nerve bundles look like in a transverse section?

answer is picture bc nerve tissue will be discussed later

A