Basic Tissues

Question 1

what is a tissue

Answer 1

collection of cells that form a particular function

Question 2

what are the 4 basic tissues

Answer 2

• epithelia
• connective
• nervous (not discussed in this section)
• muscle

Question 3

Epithelia key points

Answer 3

• covers services
• lines cavities and tissue
• form glands

characteristics:
- attached onto base membrane- avascular cells = no blood vessels in cells themselves
- bound closely together (cellularity)
- regeneration (usually quite rapid)
- polarity (apical side which faces lumen/surface and basal side attached to basement membrane)

Question 4

classification of epithelia

Answer 4

based on -
number of cells:
simple = one layer
stratified = two or more layers

shape of cell:
squamous
cuboidal
columnar

Question 5

main types of epithelia

Answer 5

• simple squamous
• keratinised stratified squamous
• non keratinised stratified squamous
• simple cuboidal
• simple columnar
• pseudostratified ciliated columnar epithelium w/goblet cells

Question 6

simple squamous

Answer 6

• flat + oval shaped nuclei
• one layer of cells
• used for diffusion cuz so thin

location - blood vessels, alveoli
smooth = so provides smooth flow of blood/air etc.

Question 7

keratinised stratified squaomous

Answer 7

flat surface cells + oval nuclei
- many layers (so is stratified)
- produce keratin on top layer
- used for protection, barrier
(- has multiple layers so if one gone, then it’s okay,
- keratin makes it tougher, waterproof)

location - skin
some oral cavity (where abrasion occurs more)

Question 8

non-keratinised stratified squaomous

Answer 8

same as keratinised but without keratin duh

• also used as protection/barrier

location - oral cavity, oesophagus

Question 9

simple cuboidal

Answer 9

square cells + round nuceli
one layer thick

used for secretion and absorption

location - forms glands, found in kidney tubules

Question 10

simple columnar

Answer 10

tall cells + oval nuclei usually basally located
one layer

used for absorption + secretion

found in GI tract
(some areas have suraface mods e.g. microvilli in small intestine)

Question 11

pseudostratified ciliated columnar epithelium w/goblet cells

Answer 11

tall cells
appear stratified - all touch the basement membran but NOT ALL reach the lumen/surface

usually modified w/ cillia and goblet cells

used as mucocilliary escalator

found in trachea & large respiratory airways
(SPECIFIC TO RESPIRATORY TRACT)

Question 12

Intercellular junctions, what proteoglycans bind cells together in epithelial cells?

Answer 12

specialised areas of cell memb that bind one cell to another

• desmosomes
• hemidesmosomes
• tight junctions
• gap junctions

Question 13

desmosomes

Answer 13

• very strong connections between adjacent cells
• resist stretching and twisting

Question 14

hemidesmosomes

Answer 14

attach cells to basement memb
- act as stabaliser and anchor cell to tissue

Question 15

tight junctions

Answer 15

• proteins that interlock between cells
• found near apical edge
• prevents passage of water & solutes BETWEEN CELLS

Question 16

gap junctions

Answer 16

• memb proteins interlock
• contains central pore
• allows movemne tof small molecules, ions between cells

found in cardiac muscle

Question 17

connective tissues: functions, main cells and extracellular matrix components

Answer 17

functions:
- structural framework
- supports, surrounds, interconnects other tissue types
- protect delicate organs
- trasport fluids/dissolved mat
- energy reserves
- defend body from microorganisms

always consist of cells within extracellular matrix

main cells:
- fibroblasts = cell type that sythesizes extracellular matrix
- adipocytes, macrophages, mast cells

extracellular matrix made up of:
- ground substance with tissue fluid in it
- has fibres : collagen and/or elastic

Question 18

classification of connecitive tissues

Answer 18

• specialised connective tissue
• connective tissue proper

Question 19

specialised connective tissue

Answer 19

e.g. blood (blood cells in plasma (extracellular fluid)
bone (bone cells in background matrix (hardened w/ Ca and Phosphate, but still counts as extracellular fluid)
cartilage (condrocytes - in matrix as well)

Question 20

connective tissue proper classification

Answer 20

classified according to
type, arrangement, abundance of the fibres, cells and ground substance

Loose arelolar (aka loose irregular)
dense irregular
dense regular

Question 21

Loose arelolar

Answer 21

• lots of ground substance
• few fibres (e.g. collagen, elastic)
  many types:
• fibroblasts (secrete hylouronan + proteins)
• adipocytes (fat cells, contain lipid droplet)
• macrophages (immune response)
• found under epithelium that lines surfaces

Question 22

dense irregular connective tissue

Answer 22

• little ground substance
• many collagen fibre bundles arranged randomly
  few cell types:
• mainly fibroblasts
• resists stretching and distension due to all of the collagen fibres

found in dermis of skin

Question 23

dense regular connective tissue

Answer 23

• little ground substance
• many densley packed collagen fibres in PARALLEL rows
• few cell types:
  mainly fibroblasts

found in tendons and ligaments
cuz quite regular tension that needs to be resisted

Question 24

Muscle tissue: function, types

Answer 24

produces movement, specialised for contraction

• skeletal
• smooth
• cardiac

similarities between ^ these 3:
- all elongated parallel to axis of contraction
- numerous mitochondria
- contractile elements

Question 25

skeletal muscle

Answer 25

- moves, stabilises the skeleton - forms sphincters in digestive or urinary tracts (e.g. bumhole contracts to stop poop) - involved in respiration (contraction relaxation of sutff) - long cylinderical cells - striated (look striped) - multinucleated ( cuz so long, usually at periphery of cell) - innervated by somatic nervous system

Question 26

xsmooth muscle

Answer 26

- located in organs, blood vessels, airways - responsible for GI movement (peristalsis) - alters diameter of airways and blood vessels (e.g. if u want to inc blood vessel by contricting, smooth muscle constricts) - short, fusiform (ie spindle shaped) - non striated - single nucleus in the middle - innervated by autonomic nervous system

Question 27

cardiac muscle

Answer 27

- found in heart fall - circulates blood, maintains BP - branched muscle fibres - striated - 1 or 2 central nuclei - cells are joined by interclated discs joined by gap junctions - innervated by autonomic nervous system

Question 28

what is transitional epithelium

Answer 28

aka urothelium foud in stratified epithelium appears cuboidal when relaxed and squamous when stretched e.g. found in bladder