Cell physiology - part 1 Flashcards
associated
uncharged, neutral e.g. glucose, urea (same as osmotic pressure)
dissociated
double number of particles so doubles osmotic pressure
electrical potential difference
energy associated with moving charged molecules across membrane
Gibbs-Donnan effect
high concentration of negative protein (GAGs???) in plasma attracts Na+ and repels Cl-
osmotic pressure (P) def and eq
pressure to exactly oppose movement of water
P = C ([solute]) x R (constant 0.082) x T (in K)
osmolarity def and eq
predicts/ measures osmosis using number of osmotically active particles in solution
osmolarity (Osmol/L) = molarity (mol/L) x number of particles
molarity def and eg
number of moles of dissolved solute per litre of solution
1M glucose = 1OsM
1M NaCl = 2OsM
hypoosmotic, hyperosmotic, isoosmotic
tonicity
relative difference of concentration of non-penetrating solutes dissolved in solution/ cell to determine direction of diffusion/ osmosis to reach equilibrium
hypotonic, hypertonic, isotonic
Starling’s law of infiltration
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
function of cell membrane
mechanical/ structural
filter (selective permeability)
markers/ signalling (receptors)
metabolic activity
electrochemical gradient driving forces
chemical driving force by concentration gradient across membrane
electrical driving force by charge differences across the membrane
phase 0/4 resting potential
inside more negative than outside
3Na+ out, 2K+ in by active transport
polarised membrane is slowly depolarised
Na+ in by diffusion via HCN channels
+ + + +
phase 1 fast depolarisation
energy of stimulus opens Na+ channels, Na+ diffuse in, positive feedback inside more positive than outside - - - - - ---------- \+ + + + ----------
phase 2 repolarisation
at certain difference, Na+ channels close K+ channels open, more K+ out inside more negative than outside \+ + + + ---------- - - - - - ----------
phase 3 afterhyperpolarisation
Na+ channels still closed movement of K+ out cause temporary undershoot inside even more negative than outside \+ + + + ---------- = = = = ----------
refractory period
time when an excitable cell (neuronal/ muscular) is incapable to respond to further stimulation
absolute refractory period
excitable cell does not respond to stimulus despite its strength
relative refractory period
excitable cell only able to respond to stimulus greater than previous
epithelial tissue
tissue covering external surface of body and lining hollow structures except blood and lymph vessels (endothelial)
function of epithelial tissue (5)
defence/ protection secretion absorption exchange/ communication sensation
types of epithelial tissue (8)
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)
tight junction
simple cuboidal
claudin and occludin proteins
prevent movement of water-soluble molecules
anchoring junction
desmosomes bind epithelial cells together (cadherin)
hemidesmosomes bind epithelial cells together (cadherin to keratin)
adherins bidn epithelial cells to basal lamina
gap junction
connexin protein bridges across adjacent cells
allows movement of inorganic ions and water-soluble molecules
exchange epithelia
junctions
e.g.
tight junctions for transport
e.g. Bowman’s capsule, alveoli, capillaries
transporting epithelia
junctions
e.g.
tight junctions
e.g. intestine
ciliated epithelia
e.g.
e.g. trachea (sweep out mucous)
protective epithelia
e.g.
e.g. skin
secretory epithelia
e.g.
exocrine/ endocrine tissues
main layers of skin
epidermis
dermis
hypodermis
epidermis layer of skin (5 layers)
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
dermis (2 layers)
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
hypodermis
energy storage in fat deposits contains fibroblasts (collagen), macrophages, adipocytes, large blood vessels and nerves
types of exocrine glands
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).