Physiology - Part 3 Flashcards
which receptors in the blood vessels do sympathetic nerves act on?
alpha-1 receptors
what effect do sympathetic nerves have on the blood vessels?
arteriolar constriction
what effect do parasympathetic nerves have on the blood vessels?
usually nothing
in which tissues does epinephrine act on beta-2 receptors?
skeletal and cardiac muscle
what effect does epinephrine acing on beta-2 receptors have on the blood vessels?
arteriolar dilation
which hormones can increase total peripheral resistance?
epinephrine
angiotensin II
vasopressin
which hormones can decrease total peripheral resistance?
epinephrine
atrial natriuretic peptide
brain natriuretic peptide
what effect does angiotensin II have on the blood vessels?
arteriolar constriction
what effect does vasopressin have on the blood vessels?
arteriolar constriction
what effect do atrial natriuretic peptide and brain natriuretic peptide have on the blood vessels?
arteriolar dilation
what are the four different types of local (intrinsic) controls?
active (metabolic) hyperaemia
pressure (flow) autoregulation
reactive hyperaemia
injury response
what is active (metabolic) hyperaemia?
an adaptation to match blood supply to the metabolic needs of that tissue
how does active (metabolic) hyperaemia work?
increased metabolic activity causes increases concentration of metabolites
triggers release of EDRF
increased flow to wash out metabolites
what is EDRF?
endothelium derived relaxing factor = nitric oxide
what is pressure (flow) autoregulation?
an adaptation to ensure that a tissue maintains its blood supply despite changes in mean arterial pressure
how does pressure (flow) autoregulation work?
decreased mean arterial pressure decreases flow
metabolites accumulate
triggers release of EDRF
arterioles dilate and flow is restored to normal
what is reactive hyperaemia?
an extreme version of pressure autoregulation
how does reactive hyperaemia work?
occlusion of blood supply causes a subsequent increase in blood flow
what happens in the injury response?
arteriolar dilation
increased blood flow
increased permeability
aids delivery of blood born leukocytes etc to injured area
what are the four ‘special’ areas of circulation?
coronary
cerebral
pulmonary
renal
which local (intrinsic) control does the coronary circulation show?
active hyperaemia
what protects the coronary circulation from sympathetic arteriolar constriction?
swamped by many beta-2 receptors
which local (intrinsic) control does the cerebral circulation show?
pressure autoregulation
what makes the pulmonary circulation different from most tissues?
decreased O2 causes arteriolar constriction
which local (intrinsic) control does the renal circulation show?
pressure autoregulation
which two broad levels of control does the body have over arteriolar radius?
extrinsic effects (neural, hormonal) local (intrinsic) effects
