PSC1002/L09 Regulation of Tissue Blood Flow Flashcards
Which blood vessels are the major site for control of total peripheral resistance (TPR)?
Arterioles
What is the major role of arterioles?
To match local blood flow to local metabolic need
How do arterioles adapt to increased oxygen demand? (2)
Vessel tone decreases/vasodilation
SM relaxes and radius increases
What determines blood flow through individual vessels?
Resistance
What 3 main physiological mechanisms regulate arteriolar radius?
Local control
Hormonal control
Neural control
Describe autoregulation of tissue blood flow. (3)
Flow stays constant with increasing pressure
Intrinsic activity of smooth muscle (myogenic response)
Safety mechanism to prevent damage to delicate blood vessels
Give 3 metabolism-derived vasodilators.
Increased CO2
Increased H+/decreased pH
Increased temperature
Decreased O2
Increased adenosine
Increased K+
Which response can override myogenic response?
Metabolic response
Give 3 hormonal vasodilators.
Histamine
Kinins
Adrenaline (B2 adrenergic receptor)
Give 3 hormonal vasoconstrictors.
Angiotensin II
Vasopressin (ADH)
Adrenaline (a1 adrenergic receptor)
Describe the role of sympathetic fibres in neural control. (3)
Release noradrenaline
Binds to a1-adrenergic receptors
Vasoconstriction
Which tissues don’t have many sympathetic fibres, but do have B2 adrenergic receptors? (3)
Heart, lungs & liver
Where are parasympathetic vasodilator fibres found? (3)
Salivary glands
External genitalia
GI tract
Describe the role of parasympathetic vasodilator fibres in neural control. (3)
Cholinergic - release ACh
Cause NO generation
Relaxes VSM
Describe how NO leads to vasodilation. (3)
NO binds to guanylyl cyclase
Stimulates production of cGMP
cGMP relaxes smooth muscle
