Physiology Flashcards
What is feedforward?
a change made in anticipation of a change
What is feedback?
a change after a change has been made
What are the three functions of the lipid bilayer?
structure
hydrophobic interior is a barrier
fluidity of the membrane
What are the two types of proteins in the lipid bilayer?
peripheral aren’t embedded
integral either span, half span or are lined to an embedded protein
What are the functions of integral proteins?
ligand-binding receptors adhesion molecules pores or channels carriers pumps enzymes intracellular signalling
What do docking-markers do?
on inner membrane surface and interact with secretory vesicles leading to exocytosis
What is the glycocalyx?
sugar coating of glycoproteins and glycolipids
What are the roles of carbohydrates in cell membranes?
different markers for embryonic development
tissue growth so tissues don’t overgrow territory
What is pulse pressure?
difference between systolic and diastolic
How is MAP calculated?
((2xdiastolic) + systolic)/3)
What is the minimum MAP needed and why is it needed?
60mmHg and must be high enough to perfuse brain, heart and kidneys but not too high that vessels burst
Where are the baroreceptors?
aortic arch and in the carotid
What happens to the firing rate of the baroreceptors when MAP increases?
increased rate of firing
What happens to the firing rate of the baroreceptors when MAP decreases?
decreased rate of firing
What happens to CNS afferent impulses that reach the cardiovascular control centre?
info sent to brain areas
generates vagal outflow to the heart
regulates spinal sympathetic neurones
What does MAP equal and what does CO equal?
MAP=COxSVR
CO=SVxHR
What does noradrenaline act on to change HR and what does it cause?
beta 1 receptors to cause tachycardia
What does acetylcholine act on to change HR and what does it cause?
muscarinic receptors to cause bradycardia
Does parasympathetic or sympathetic affect ventricular contraction?
only sympathetic
What does vasoconstriction do?
increases SVR and MAP
What does vasodilation do?
decreases SVR and MAP
What does noradrenaline act on to change vasoconstriction/vasodilation?
alpha receptors to produce parasympathetic vasomotor tone at rest
Which one does not innervate the arterial smooth muscle- sympathetic or parasympathetic?
parasympathetic does not innervate the arterial smooth muscle
What does increased sympathetic discharge do to SVR?
increases it
What does decreased sympathetic discharge do to SVR?
decreases it
What is the process of events after there is a decreased ABP?
decreased baroreceptor discharge
CV centre in medulla causes
- decreased vagal so increased HR so increased CO so increased ABP
- increase sympathetic so increased SV and HR so increased CO so increased ABP
- increased sympathetic constrictor tone so increased venoconstriction (increased SV) and increased vasoconstriction (increased SVR)
What is the process of events after there is a increased ABP?
increased baroreceptor discharge
CV centre in medulla causes
- increased vagal so decreased HR so decreased CO so decreased ABP
- decrease sympathetic so decreased SV and HR so decreased CO so decreased ABP
- decreased sympathetic constrictor tone so decreased venoconstriction (decreased SV) and decreased vasoconstriction (decreased SVR)
Why do baroreceptors only provide short-term control of ABP?
they re-set at a higher steady state
What is normal body temperature?
37.8
What is normothermia?
the optimum temperature for cellular metabolism and function
What is normal tympanic temperature?
(ear drum)
35.5-37.5
What does the body gain heat from?
metabolism
radiation
convection
conduction
What does the body lose heat from?
conduction, convection, radiation and evaporation
What is basal metabolic rate?
minimum amount of energy required to sustain the body
What is the basal metabolic rate increased by?
hormones (adrenaline, noradrenaline and thyroxine)
What does conduction depend on?
temperature gradient and thermal conductivity
Where are the central thermoreceptors?
hypothalamus and abdominal organs
Where are the peripheral thermoreceptors?
skin
What are the temperature effectors?
skeletal muscles
skin arterioles
sweat glands
What is the posterior hypothalamic centre activated by?
cold
What is the anterior hypothalamic centre activated by?
hot/warmth
What happens in the cold response?
vasoconstriction
increased muscle tone
shivering
increased voluntary muscle movement
What happens in the hot response?
vasodilation
sweating
decreased muscle tone
decrease voluntary movement
How is the temperature reset in fever?
chemicals from macrophages act as endogenous pyrogens
stimulate the release of prostaglandins in hypothalamus
reset thermostat to higher temperature
initiate cold response to heat body to new set point
fever
What stops fever?
stopping pyrogen release
What temperature is fever?
38-40 degrees
What temperature is hyperthermia?
above 40 degrees
What temperature is hypothermia?
below 35 degrees
What are the factors affecting Fick’s law of diffusion?
concentration gradient magnitude of surface area lipid solubility molecular weight of substance diffusion distance
What is electrochemical gradient?
net effect of simultaneous electrical and concentration gradients on the ion
What is osmolarity?
the concentration of osmotically active particles in a solution
What is tonicity?
the effect a solution has on cell volume (iso-hypo-hypertonic)
What are the types of selective transport?
carrier-mediated
vesicular
What is carrier-mediated transport determined by?
specificity
saturation
competition
What is Tm?
the levelling off when all carriers are full
What are the types of carrier-mediated transport?
facilitated diffusion
active transport
What is primary active transport?
energy required directly to move substances against their concentration gradient
What is secondary active transport?
energy require but not used directly, carrier moves molecule uphill by secondhand energy store in the form of an ion concentration gradient
What are the roles of the sodium-potassium pump?
established these ions’ gradients
regulates cell volume
energy driving the pump serves as energy source for secondary active transport
What are the types of secondary active transport?
symport (same direction)
antiport (opposite directions)
How is Em created?
differences in concentration and permeability of key ions
What are the permeabilities of K+ and Na+ across the membrane?
the membrane is much more permeable to K+ than Na+ (100x)
What ions can’t move across the membrane?
large negatively charged anions
What are the two forces moving K+ ions?
concentration gradient which moves them out
electrical gradient which moves them in
What is the normal membrane potential of Ek?
-90mV
What is the Nernst equation used to calculate?
the equilibrium potential for any ion
What are the forces acting on Na+?
concentration gradient moves them in
electrical gradient moves them out
What is normal Ena?
+61mV
What is resting potential for a cell and why?
-70Mv as K+ permeability is higher so the membrane favours the equilibrium of K+ over that of Na+
What does the Na+/K+ pump do?
maintains the K+ and Na+ gradient and has a slight hyper polarising current
What is the most important factor in setting the Em?
K+ gradient
