Physiology Flashcards
features of the membrane
selectively permeable
maintains ion conc
fluid
phospholipid stucture
head is hydrophillic -ve
tail is non-polar hydrophobic
what can and cannot cross the membrane?
can: small uncharged moleucles eg o2 h20
ions cannot cross
functions of the cell membrane
maintain fluidity
barrier to molecules
structure
difference between transmembrane, peripheral and integral proteins
transmembrane: integral proteins that spans the entirety of the membrane
peripheral: not embedded
integral: embedded
difference between channels and pumps
channels allow passive flow
pumps: use energy to drive against concentration gradient
different types of cell junctions and function
gap junctions: allow charge to flow between cells
desmosones: anchors cells together
tight junctions: join the lateral edges of epithelial cells`
cholesterol in cell membranes
gives membrane stability
ensures not too fluid
factors affecting diffusion
1) conc gradient
2) surface area of membrane
3) lipid solubility of membrane
4) molecular weight
5) distance through which diffusion must take place
electrochemical gradient
difference in charge between 2 areas
osmosis
movement of water through a selectively permeable membrane down a concentration gradient
osmolarity
concentration of osmotically active particles present in a solution
tonicity
the ability of an extracellular solution to influence the movement of water in or out of a cell by osmosis
hypotonic
less solute and more water than another solution
hypertonic
more solute and less water than another solution
isotonic
same amount of water and solute than another solution
2 types of selective transport
carrier mediated transport and vesicular transport
carrier mediated transport and 2 types
substance binds to a carrier and undergoes a conformational change that transports the substance
2 types: facilitated diffusion and active transport
difference between primary and secondary active transport
primary: directly requires energy
secondary: an ion supplies the driving force
symport in active transport
ion(Na) and solute move in the same direction
antiport in active transport
na and solute move in opposite direction
vesicular transport and types
movement of substances across a vesicle membrane
exocytosis: ejects substances
endocytosis: moves into cells
tissue
a group of cells with similar structure and function
organ
2 or more tissues that function together for a particular function
system
a group of organs working together for for a related function
homeostasis
maintenance of a steady state within our bodies
what must a physiological control system be able to do?
sense deviation
integrate the information
make adjustments
intrinsic control system
local controls inherent in an organ
extrinsic control system
mechanisms initiated outwith an organ e.g. by hormonal or nervous control
feedforward
changes made in anticipation of a change
feedback
changes made after the change has been detected
2 types : positive and negative
differences between positive and negative feedback systems
positive: amplifies an initial change
negative: opposes an initial change
what should core body temperature be
37.8: normothermia
diurinal variation in body temp
temp is lowest in the AM
where to measure temperature
ear: 35.5-37.5
rectal: 36.7-37.5
sensor, control centre and effector of temp control
sensor: central and peripheral thermoreceptors
control centre: hypothalamus
effectors: behaviour, skeletal muscle, sweat glands, skin arterioles
difference between anterior and posterior hypothamalus
posterior hypothalamus: activated by cold
anterior hypothalamus: activated by warmth
mechanisms of a fever
chemicals from macrophages (infection) stimulate the release of prostaglandins, rests at a higher temp so the body initiates mechanisms to inc temp
hyperthermia
extreme uncontrolled increase in body temp above 40
hypothermia
drop in body temp below 35`
blood pressure
the outward hydrostatic pressure exerted on the walls o the blood vessel by blood
difference between top and bottom number of BP
top: systolic: BP when the heart contracts
bottom: diastolic: BP when the heart relaxes
hypertension
blood pressure equal to or more than 140/90
pulse pressure
difference between diastolic and systolic blood pressure
mean arterial blood pressure and how to calculate it and normal range
avg blood pressure during a single cardiac cycle ((2xdiastolic) + systolic )/3
shoul be between 70-105
baroreceptor
receptor sensitive to pressure change`
how to calculate MAP
COxSVR
systemic vascular resistance
the sum of the resistance of all the vasculature in the systemic circulation
autorhythmicity
heart is capable of beating rhythmically in the absence of external stimulus
major resistance vessels
arterioles
what regulates systemic vascular resistance?
smooth muscle
neurotransmitter and receptor of vascular smooth muscle
neurotransmitter is noradrenaline acting on α r
eceptors
vasomotor tone
smooth muscles are partially constricted at rest due to the discharge of sympathetic nerves resulting in the release of adrenaline
effect of increasing sympathetic discharge
increased release of adrenaline resulting in increased vasomotor tone ie vasoconstriction
effect of decreasing sympathetic discharge
decreased release of adrenaline, resulting in reduced vasomotor done ie vasodilation
membrane potential
difference in charge across a membrane
the membrane itself is not charged
resting membrane potential
constant in non-excitable cells, and in excitable cells at rest.
membrane potential abbreviation
Em
cation
positively charged ion eg Na and K
conc gradients of K and Na
K- potassiout
na-sodin
opposing factors that act on K
the concentration gradient and the electrical gradient
equilibrium potential for K
when the concentration and chemical gradients for K balance out and there is no net movement
what is Em close too and why
it is close to E: the resting potential of potassium
it is not identical as there is a small influx of sodium
anion
negative ion
glycocalyx layer
short carbohydrate chains bound to proteins and lipids
is the membrane more permeable to K or Na?
K
where are BP baroreceptors found?
aortic arch and carotid sinus
normal glucose
5mmol
fever is a temperature of?
38-40
function of carbohydrates in cell membrane
self-identity markers enabling cells to identify and interact with one another
3 roles of the Na/K pump
control cell volume
control solute concentration
energy used to drive the pump indirectly serves as an energy source for secondary active transport
resting membrane potential of a nerve cell
-70
hormones contorlling glucose
in absorptive and postabsorptive states: insulin and glucagon (pancreas)
in emergencies: glucagon (adrenal gland)
during starvation: Cortisol (adrenal) and growth hormone (pituitary)
Pancreatic Islets of Langerhans
clusters of cells in the pancreas that produce hormones
what is glucagon
hormone
what cells produce somatostatin
delta
what cells produce glucagon
alpha
what cells produce insulin
beta
insulin
hormone of the fed state
favours anabolism
Lowers glucose by stimulating uptake from blood and activating liver enzymes
1
glucagon
favours catabolism
hormone of the hungry state
Raises glucose by increasing glycogenolysis, inhibiting liver glycogen synthesis, promoting liver gluconeogenesis
what causes insulin to be secreted?
Increased glucose, amino acids, parasympathetic activity, glucagon, GIP
what stops insulin being secreted?
Decreased glucose, increased sympathetic activity
what causes glucagon to be released?
Decreased blood glucose
Amino acids
Sympathetic nerve activity
what inhibits glucagons release
Raised blood glucose
Insulin
diabetes mellitus type 1
o Early onset
o Little/no insulin secretion
o Defect in beta cells
o Insulin injections required
diabetes type 2
o Adult onset
o Insulin secretion may be normal
o Defect in insulin sensitivity
o Diet/exercise/oral drugs
adrenaline
- Raises glucose
- Stimulates glycogenolysis
- Stimulates gluconeogenesis
- Released during short term emergencies
cortisol
- Raises glucose
- Stimulates protein catabolism
- Stimulates gluconeogenesis
- Stimulates lipolysis
- Not important for rapid mobilisation of fuel
growth hormone
- Anterior lobe of pituitary
- In response to starvation
o Decreases glucose uptake by muscle
o Mobilises glucose from liver
o Promotes lipolysis in fat cells
