Nervous Regulation of the Circulation Flashcards
What is the primary nervous system that regulates circulation?
sympathetic nervous system
What nervous system assists in regulation of heart function?
parasympathetic nervous system
Where do the sympathetic vasomotor nerves leave the spinal cord?
through thoracic and 1st 1 or 2 lumbar spinal nerves
The SNS innervates all blood vessels except what?
- capillaries
- precapillary sphincters
- metarterioles
Stimulation of the SNS does what to the volume of veins?
decreases
SNS innervation of small arteries and arterioles allows for what?
vasoconstriction
What is the condition called in which blood vessels are inadequately filled and blood can’t circulate normally?
circulatory shock
What causes hypovolemic shock?
losing blood volume
What causes vascular shock?
extensive massive vasodilation of the vessels (possibly caused by drugs or an allergic reaction)
What causes cardiogenic shock?
the heart stops working – pump failure (caused by some kind of myocardial damage to the muscle of the heart)
What is a massive bacterial infection that travels throughout the blood?
septicemia
Do SNS nerves carry more vasoconstrictor fibers or vasodilator fibers?
vasoconstrictor fibers
Vasoconstrictor fibers are largely distributed where?
- kidneys
- intestines
- spleen
- skin
Where is the vasomotor center found?
brainstem
What 3 area are found in the vasomotor center?
- vasoconstrictor area
- vasodilator area
- sensory area
What does the sympathetic vasoconstrictor tone maintain?
- normal vasomotor tone
- blood pressure
The vasoconstrictor area secretes what?
norepinephrine
Function of the vasodilator area?
inhibits the vasoconstrictor area
What 2 nerves innervate the vasomotor center?
- vagus
- glossopharyngeal
What does the adrenal medulla secrete when stimulated by the SNS?
norepinephrine and epinephrine –> causing vasoconstriction
Function of the cardiac center?
adjusts rate and force of heart contraction to meet needs of the body
What 2 centers are included in the cardiac center?
- cardioaccelerator center
- cardioinhibitory center
What nervous system controls the cardioacceleratory center?
SNS
What nervous system controls the cardioinhibitory center?
PSNS
What 3 changes do you need to cause in increase in arterial pressure?
- most arterioles constrict
- veins and other large vessels constrict
- SNS stimulation of heart
An increase in arterial pressure simultaneously stimulates what two centers?
- vasoconstrictor
- cardioaccelerator
Baroreceptors respond to what?
changes in pressure in the blood vessels - respond to stretch or lack of stretch in vessel walls
ex: tells the brain to vasodilate if blood pressure is too high
Chemoreceptors respond to what?
- changes in O2, CO2, and H+
- -> will signal the brainstem to vasodilate/vasoconstrict depending on blood gas
Chemoreceptors are located where?
carotid bodies and aortic bodies
Where are baroreceptors located?
- carotid sinuses
- aortic arch
- walls of nearly every large artery in the neck and thorax
Chemoreceptors stimulate what?
nerve fibers traveling to the vasomotor center
atrial reflexes respond to what?
change in pressure (stretch receptors)
How does the body respond to cerebral ischemia?
- strong reaction of vasoconstrictor and cardioaccelerator centers
- large rise in systemic arterial pressure
- increases MAP to ~250mmHg
What causes cerebral ischemia?
- blood flow to vasomotor center severely decreases
What is the most powerful activator of SNS vasoconstrictor system?
cerebral ischemia
What does SNS do to fix cerebral ischemia?
restores BP by increasing HR and TPR
