Human Phys 5.1 Flashcards
What is the role of the autonomic nervous system?
Redistribution of blood flow
Increasing pumping activity of the heart
Rapid control of arterial pressure
What is the sympathetic nervous system important in the control of?
Circulation(cardiac function)
What is the parasympathetic nervous system important for?
Regulating heart function
What do the sympathetic nerve fibers innervate?
All vessels except capillaries, precapillary sphincters, and some metarterioles
What do innervation of small arteries and arterioles allow?
Sympathetic nerves to increase vascular resistance
How are large veins and the heart innervated?
Sympathetically
How does the parasympathetic control the heart rate?
Vagus nerve
Where does the vasomotor center transmit impulses?
Downward through the cord to almost all blood vessels
Where is the vasomotor center located?
Bilaterally in the reticular substance of the medulla and the lower third of the pons
What is the vasomotor center composed of?
Vasoconstrictor area (SNS)
Cardiac accelerator center (SNS)
Cardiac decelerator center (PNS)
What is the effect of sympathetic outflow?
Effect on SA node (increase HR)
Effect on cardiac muscle (increase contractility and SV)
Effect on arterioles (vasoconstriction and increased TPR)
Effect on veins (venoconstriction and increased venous return)
What is the effect of parasympathetic outflow?
Effect on SA node via vagus nerve (decreased HR)
Where does the vasomotor area of the vasomotor center transmit signals continuously?
To a sympathetic nerve fiber called sympathetic vasoconstrictor tone
What do signals sent to the sympathetic vasoconstrictor tone do?
Maintain partial state of contraction in blood vessels called vasomotor tone
What does the cardiac accelerator center of vasomotor center do?
Controls heart activity by increasing HR and contractility
What does the cardiac decelerator center of the vasomotor center do?
Transmit signals via vagus nerve to decrease HR
What is the neurotransmitter for the vasoconstrictor nerves?
Norepinephrine
What does the adrenal medulla secrete?
Epinephrine and norepinephrine
What does the secretion of epinephrine and norepinephrine from the adrenal medulla do?
Constricts blood vessels via alpha adrenergic receptors
What can epinephrine do?
Dilate vessels through beta receptors
How can the nervous system via the vasomotor center increase arterial pressure?
Constricting almost all arterioles of the body which increases TPR
Constricting large vessels of the circulation thereby increasing venous return and CO
Directly increases CO by increasing HR and contractility
How can rapid increases in arterial pressure occur?
During exercise or with fright
