Histology (tissues)

Question 1

histology

Answer 1

the study of tissues

Question 2

tissues

Answer 2

a group of cells with similar structure and function

Question 3

4 major tissues

Answer 3

epithelial
connective
muscle
nervous

Question 4

cell junctions

Answer 4

in some tissues

• points of contact b/w adjacent cells- seen in epithelial tissue, some nervous and muscle cells
• formed by cell membrane proteins

Question 5

types of cell junctions

Answer 5

tight
anchoring
gap

Question 6

tight junctions

Answer 6

are a partial fusion of specific proteins on the lateral surface of the cell membrane

• form ring-like right seal
• prevents material from passing b/w cells eg. bacteria, proteins, sometimes fluid or ions (depending on the tissue)

Question 7

anchoring junctions

Answer 7

eg. desmosomes

- protiens that fasten cells to each other and or extracellular material (“rivets” cells together)

Question 8

Gap junctions

Answer 8

open channels (formed by proteins) through the adjacent cell membranes interconnecting the cytosols of the cells

• allows ions/small molecules to pass from on cell to another
• tissues can then work as a unit:
• important in cardiac and smooth muscle (allows synchronization of contractions)
• also found in epithelial tissue

Question 9

epithelial tissue

Answer 9

lining tissue

• covers body surface
• lines body/organ cavities

Question 10

organ cavity

Answer 10

lumen

Question 11

classification of epithelia

Answer 11

• most subtypes are classified and named according to:
  1. number of cell layers sitting on the basement membrane
• one layer=simple
• more than one layer = stratified
  2. shape of the ells in the apical layer (=layer touching the free surface)
• flattened=squamous
• round or cube shaped=cuboidal
• rectangular=columnar
  1. simple epithelia
  2. stratified epithelia
  3. pseudo-stratified epithelia
  4. transitional epithelia
  5. glandular epithelium

Question 12

simple epithelia

Answer 12

1 layer

• allow exchange of molecules (gasses, nutrients)- absorption/secretion
• 3 subtypes

Question 13

simple squamous

Answer 13

1 layer of squished flat cells

eg. lungs

Question 14

simple cuboidal

Answer 14

1 layer of cube shaped cells

eg. kidneys

Question 15

simple columnar

Answer 15

1 layer of column shaped tall and thing cells

eg stomach, small intestine

Question 16

stratified epithelia

Answer 16

> 1 layer
-protective (areas of abrasion)
3 subtypes

Question 17

stratified squamous

Answer 17

apical cells squished flat

eg. skin

Question 18

stratified cuboidal

Answer 18

apical cells cube shaped

- rare

Question 19

stratified columnar

Answer 19

apical cells column shaped

-rare

Question 20

pseudostratified epithelia

Answer 20

appears stratified (nuclei at diff levels) but all cells sit on basement membrane (=simple)
eg. lines most of respiratory tract and ciliated

Question 21

transitional epithelia

Answer 21

cell shape and layering varies with stretching

• only in inner lining of urinary system
• cuboidal to squamous when stretched

Question 22

glandular epithelium

Answer 22

-if the epithelial cells from a gland, the cell layer/cell shape classification is not longer used
-for secretion
-subtypes :
exocrine and endocrine glands

Question 23

exocrine glands

Answer 23

• secret products onto body surface or into a body cavity
• can be unicellular eg. goblet cells
• can be multicellular
• consists of secretory and duct cells (ducts connect secretions to surface or cavity)
  eg. glands: sudoriferous (sweat), sebaceous (oil), mammary, digestive

Question 24

endocrine glands

Answer 24

no ducts
secretions (hormones) directly into the blood
eg. thyroid gland secretes thyroid hormone

Question 25

epithelia functions

Answer 25

``` 1. protection (often stratified squamous) eg. epidermis of skin 2. secretion (glandular epithelium) eg. thyroid, sweat glands 3. control and permeability (typically simple epithelia, exchange of material) eg. kidney, intestine, capillaries ```

Question 26

Connective tissue CT

Answer 26

mainly supports and connects tissues -cells far apart, separated by extracellular matrix (extracellular material gives CT subtypes their identifying characteristics) -variable vascularity

Question 27

CT Cell types

Answer 27

``` cell names ending in: -blast-create matrix eg. osteoblast, chondroblast, fibroblast -Cyte- maintain matrix eg. osteocyte, chondrocyte,fibrocyte -clast- break down matrix eg osteoclast ```

Question 28

matrix composition

Answer 28

fibres ground substance water

Question 29

fibres

Answer 29

proteins - collagen fibres (for strength) - elastic fibres (containing elastin)- allow stretch and recoil) - reticular fibres (from networks- eg. CT part of basement membrane)

Question 30

ground substance

Answer 30

- unstructured material surrounding the extracellular fibre and cells - composed of a) instertial fluid (ISF) b) proteoglycans

Question 31

ISF | instertial fluid

Answer 31

part of blood plasma that leaks out of capillaries and surrounds cells

Question 32

proteoglycans

Answer 32

-proteins and carbohydrate molecule

Question 33

CT classification

Answer 33

CT proper cartilage bone blood

Question 34

CT proper

Answer 34

cells= fibroblasts/fibrocytes except adipose tissue (adipocytes) types are loose or dense

Question 35

loose CT

Answer 35

areolar CT or Adipose CT

Question 36

areolar CT

Answer 36

- loosely arranged collagen and elastin fibres surrounded by ground substance (hyaluronic acid) - higly vascular eg. lamina propria

Question 37

adipose CT

Answer 37

- verly little matrix - cells large (adipocytes), store triglycerides-tissue looks like chicken wire - highly vascular

Question 38

Dense CT

Answer 38

-many fibres (aka fibrous CT) -liggle groups substance non-vascular 2 types: reuglar and irregular

Question 39

dense regular CT

Answer 39

- collagen fibres running in the same direction | - eg. tendons, ligaments

Question 40

dense irregular CT

Answer 40

-collagen fivres arranged irregularly | eg dermis of skin

Question 41

Bone

Answer 41

cells=osteocytes (in lacunae), osteoblasts, and osteoclasts - matrix: - fibres=collagen - ground substance = hydroxyapatite (inorganic Ca++ and phasphate salts) - water - very vascular

Question 42

cartilage

Answer 42

cells= chondrocytes (cells located in lacunae=cavities in the matrix) and chondroblasts - matrix: - fibres=collagen and elastin - ground stubstance =chondroitin sulphate, hyaluronic acid - water - avascular-heals slowly - eg hyaline cartilage of trachea, ribs, ends of long bones

Question 43

bone

Answer 43

cells=red blood cells and white blood cells | -matrix (fluid)= plasma (contains fibre proteins, ground substance, water)

Question 44

muscle tissue

Answer 44

-contractile -subtypes: skelatal (striated) cardiac (striated) smooth (non-striated)

Question 45

nervous tissue

Answer 45

conducts electrical impulses (neurons) or supports and protects neurons ( glial cells)