26: Unique regional circulations Flashcards
(23 cards)
Characteristics unique to different vascular beds
- Balance of intrinsic vs extrinsic
- A-1 or 2 or B2 receptor concentration
- Unique anatomical structure
Extrinsic
autonomic nervous system
Hormonal regulation through receptors
Intrinsic
Autoregulation to environment
Automatic response of cells to metabolies
Cutaneous circulation
extrinsic control mechanisms predominate
High A-receptor concentration
low metabolic demands of skin
What sets temperature
Hypothalamus
Features of skin
Large
arterio-venous shunts to divert blood
Metabolic escape
Skeletal bed
Large vascular bed
Both extrinsic and intrinsic regulation
What happens during activation of skeletal muscle
Intrinsic regulation overrides sympathetic activation
what receptor causes muscle vasculature vasodilation
b-2 receptors
What happens during exercise
adrenal stimulation
epinephrine release
Intrinsic control must quickly meet metabolic needs
What is an important regulator of muscle venous return
muscles pumping as they move
How does skin a muscle vaculature respond to sympathetic drive
Very sensitive
Smooth muscle constricts to increase resistance
Coronary circulation
Intrinsic mechanisms dominate
low A receptor conc
Vasodilators of coronary circulation
Increase: CO2
Decrease: O2, H+, and adenosine
Cerebral circulation
Metabolic regulation predominates
Tightly regulated
main controller of metabolic regulation
CO2
Splanchnic circulation
Sympathetic innervation important: shunts blood away from non vital
Liver
Portal vein does not autoregulate during prolonged constriction
Ascites
increased peritoneal cavity fluid
Right heart failure
Ascites- hepatic hypertension
hepatic portal venous pressure rises
Hepatic scarring- increased resistance to inflow
Pulmonary circulation
Low resistance
Respond to increase in perfusion pressure with a decrease in resistance
In pulmonary circulation, what does hypoxia trigger
vasoconstriction
What is a cause of pulmonary hypertension
high altitude
