Nervous Regulation of the Circulation and Rapid Control of Arterial Pressure Flashcards
T/F parasympathetic plays a major role in regulation of circulation
False. Plays a minor role but important role in regulating heart function.
Sympathetic nerves fibers innervate all vessels except
capillaries, precapillary, precapillary sphincters and some metarterioles
Sympathetic nerves release what hormone and activates what receptor?
Noepinephrine on alpha adrenergic receptors on smooth muscle cells in blood vessels.
Adrenal medulla
Holds/releases noepinephrine and epinephrine that’ll be transmitted to blood vessels.
Sympathetic vasoconstrictor especially effect
Kidneys, gut, spleen, and skin but less potent in skeletal muscle and brain.
Sympathetic stimulation increases or decreases arterial pressure?
Increases
Sympathetic stimulation causes 3 things to increase arterial pressure
1-Constricting almost all arterioles of body to increase total peripheral resistance (alpha receptor)
2-Constrict large veins which increases venous return and cardiac output. DECREASES COMPLIANCE (alpha receptor)\
3-Stimulating heart to increase heart rate and contractility (beta receptors)
THESE THREE THINGS ALWAYS HAPPEN WHEN SYMPATHETIC STIMULATON.
Vasomotor Center
Collection of cell bodies in medulla oblongata (brain stem cell) that regulates blood pressure and cardiac function primarily through the ANS.
3 Important areas of the vasomotor center
Vasoconstrictor region
Cardiac region
Sensory region
Vasoconstrictor area tones
Transmits signals CONTINUOUSLY to sympathetic nerve fibers. Sympathetic tone (think how SA node fires continuously)
These impulses maintain partial state of contraction in smooth muscle cells in blood vessels=VASOMOTOR TONE
If you cut sympathetic tone to blood vessels what would happen?
No constriction of blood vessels. So atrial pressure would fall, No noepinephrine would be released to stimulate constriction in blood vessels.
Cardiac centers
1-Cardiac accelerator area: increases HR. Transmits signals to regulate sympathetic nerves to the heart. Noepinephrine activating beta receptors.
2-Cardioinhibitory area: decrease HR. Dorsal motor nuclei of vagus nerve. Transmits parasympathetic impulses to heart through vagus nerve. Acetylcholine actiating muscarinic receptors.
T/F There are parasympathetic nerves to the heart
True
Sensory area
Located in nucleus tractus solitarius (NTS)
Receives sensory input from baroreceptors located in body
Output controls activity of: vasoconstrictor area. cardiac inhibitory area, cardiac accelerator area
REFLEX CONTROL OF CIRCULATORY FUNCTION
Reflex control of circulatory
Reflex= what happens after increase/decrease of blood pressure.