Cell physiology - part 1

Question 1

associated

Answer 1

uncharged, neutral e.g. glucose, urea (same as osmotic pressure)

Question 2

dissociated

Answer 2

double number of particles so doubles osmotic pressure

Question 3

electrical potential difference

Answer 3

energy associated with moving charged molecules across membrane

Question 4

Gibbs-Donnan effect

Answer 4

high concentration of negative protein (GAGs???) in plasma attracts Na+ and repels Cl-

Question 5

osmotic pressure (P) 
def and eq

Answer 5

pressure to exactly oppose movement of water

P = C ([solute]) x R (constant 0.082) x T (in K)

Question 6

osmolarity
def and eq

Answer 6

predicts/ measures osmosis using number of osmotically active particles in solution
osmolarity (Osmol/L) = molarity (mol/L) x number of particles

Question 7

molarity 
def and eg

Answer 7

number of moles of dissolved solute per litre of solution
1M glucose = 1OsM
1M NaCl = 2OsM
hypoosmotic, hyperosmotic, isoosmotic

Question 8

tonicity

Answer 8

relative difference of concentration of non-penetrating solutes dissolved in solution/ cell to determine direction of diffusion/ osmosis to reach equilibrium
hypotonic, hypertonic, isotonic

Question 9

Starling’s law of infiltration

Answer 9

at arteriole end, hydrostatic pressure > oncotic pressure so water moves out of capillary
at venous end, hydrostatic pressure < oncotic pressure so water moves into capillary
net accumulation of water in intistial space flows into lymph vessels, transport back to circulation

Question 10

function of cell membrane

Answer 10

mechanical/ structural
filter (selective permeability)
markers/ signalling (receptors)
metabolic activity

Question 11

electrochemical gradient driving forces

Answer 11

chemical driving force by concentration gradient across membrane
electrical driving force by charge differences across the membrane

Question 12

phase 0/4 resting potential

Answer 12

inside more negative than outside
3Na+ out, 2K+ in by active transport
polarised membrane is slowly depolarised
Na+ in by diffusion via HCN channels

+ + + +

Question 13

phase 1 fast depolarisation

Answer 13

energy of stimulus opens Na+ channels, Na+ diffuse in, positive feedback 
inside more positive than outside 
 - - - - - 
----------
 \+ + + + 
----------

Question 14

phase 2 repolarisation

Answer 14

at certain difference, Na+ channels close
K+ channels open, more K+ out 
inside more negative than outside 
\+ + + + 
----------
 - - - - - 
----------

Question 15

phase 3 afterhyperpolarisation

Answer 15

Na+ channels still closed 
movement of K+ out cause temporary undershoot 
inside even more negative than outside 
\+ + + + 
----------
 = = = = 
----------

Question 16

refractory period

Answer 16

time when an excitable cell (neuronal/ muscular) is incapable to respond to further stimulation

Question 17

absolute refractory period

Answer 17

excitable cell does not respond to stimulus despite its strength

Question 18

relative refractory period

Answer 18

excitable cell only able to respond to stimulus greater than previous

Question 19

epithelial tissue

Answer 19

tissue covering external surface of body and lining hollow structures except blood and lymph vessels (endothelial)

Question 20

function of epithelial tissue (5)

Answer 20

defence/ protection
secretion
absorption
exchange/ communication
sensation

Question 21

types of epithelial tissue (8)

Answer 21

simple squamous (leaky/ tight junctions)
simple cuboidal (tight junctions)
simple columnar (brush like)
stratified squamous
stratified cuboidal
stratified columnar
transitional (made up of difference cells e.g. squamous, cuboidal)
pseudostratified columnar (one layer of irregular cells)

Question 22

tight junction

Answer 22

simple cuboidal
claudin and occludin proteins
prevent movement of water-soluble molecules

Question 23

anchoring junction

Answer 23

desmosomes bind epithelial cells together (cadherin)
hemidesmosomes bind epithelial cells together (cadherin to keratin)
adherins bidn epithelial cells to basal lamina

Question 24

gap junction

Answer 24

connexin protein bridges across adjacent cells

allows movement of inorganic ions and water-soluble molecules

Question 25

exchange epithelia
junctions
e.g.

Answer 25

tight junctions for transport

e.g. Bowman’s capsule, alveoli, capillaries

Question 26

transporting epithelia
junctions
e.g.

Answer 26

tight junctions

e.g. intestine

Question 27

ciliated epithelia

e.g.

Answer 27

e.g. trachea (sweep out mucous)

Question 28

protective epithelia

e.g.

Answer 28

e.g. skin

Question 29

secretory epithelia

e.g.

Answer 29

exocrine/ endocrine tissues

Question 30

main layers of skin

Answer 30

epidermis
dermis
hypodermis

Question 31

epidermis layer of skin (5 layers)

Answer 31

stratum corneum - coneocytes, cornified envelope, keratin
stratum lucidum - translucent only in palms and soles
stratum granulosum - keratinocytes
stratum spinosum - suprabasal keratinocytes
stratum basale - basal keratinocytes that form basal lamina to attach to dermis, melanocytes produce melanin

Question 32

dermis (2 layers)

Answer 32

papillary dermis - collagen, intertwines with rete ridges of epidermis, hair follicles, sweat glands, sebaceous glands, lymph and blood vessels
reticular dermis - thick layer provides tensile strength, thermo and mechanoreceptors

Question 33

hypodermis

Answer 33

energy storage in fat deposits 
contains fibroblasts (collagen), macrophages, adipocytes, large blood vessels and nerves

Question 34

types of exocrine glands

Answer 34

apocrine glands – a portion of the cell membrane that contains the excretion buds off and releases the content (e.g. mammary gland)

merocrine gland – the cells excrete their substances by exocytosis (e.g. pancreatic acinar cells, sweat glands)

holocrine glands - the entire cell explodes to excrete its substance (e.g. sebaceous gland).