Phys- Regulation of Blood Pressure Flashcards
Describe baroreceptor stretch receptors
highly branched, enmeshed within the elastin matrix of the vessel wall
Name some things that infulence MAP
1.) Cardiac 2.) Systemic Nervous System 3.) Humoral 4.) Renal Fluid Volume control 5.) Local control
Reflex arc
feedback loops in which a stimulus is transmitted via afferent pathways to the central nervous system wher it gets processed and integrated to generate an appropriate output signal that is sent to the periphery via efferent pathway to an effector organ
Pressor Center Response to increased pressure
In response to increased pressure the pressor center causes a decrease in sympathetic output and passive vasodilation
Rate of baroreceptor firing is greatest during (systole/diastole) and decreases during (systole/diastole)
Greatest during systole (get burst of activity) and decreases during diastole
Medulla Oblongata
contains a number of important information receiving and integrating celnters for both the cardiovascular and respiratory systems. Stimulation results in specific effects
Which baroreceptors are tonically active (what does this mean)
Carotid baroreceptors (always firing)
relationship between arterial pressure and firing frequency in carotid baroreceptors
increased pressure causes distention and increased firing freqency (decreased pressure causes decreased fring frequency )
Cerebral cortex and regulation
1.) Emotional stimuli (extreme fear, anxiety, embarassment) can alter efferent output 2.) Painful stimuli can evoke powerful sympathetic stimulation that originates in the spinal cord
what is the driving force for tissue perfusion
arterial blood pressure
increased sympathetic activity to arterioles causes
ACTIVE vasoconstriction
Cardioinhibitory center
tonically active. Controls PARASYMPATHETIC (vagal output)
CO equation
CO= HR x SV
Pressor Center
TONICALLY ACTIVE. Controls peripheral resistance by controling sympathetic output. In face of increased pressure it causes a decrease in sympathetic output and passive vasodilation
Baroreflex negative feedback system
in response to DECREASED ARTERIAL PRESSURE the reflex acts to increase sympathetic activity - increase in caradiac output and causes peripheral vasoconstriction to raise pressure. In response to INCREASED ARTERIAL PRESSURE the reflex decreases sympathetic activity and increases sympathetic activity to decrease blood pressure
Why is the baroreflex considered superior to the other mechanisms that influence blood pressure
barorelflex mechanism responds most rapidly (within 15-20 seconds) and with a greater gain that other mechanisms
what is the pimary mechanism involved in regulating moment to moment changes in arterial blood pressure
Barorelflex
which “center” is not tonically active
Depressor center
Components of the baroreflex arc
1.) Baroreceptors in the carotid sinus, aortic arch, and other large thoracic arteries 2.) Afferent pathways in cranial nerves IX and X 3.) Medullary centers 4.) Efferent autonomic (sympathetic and parasympathetic) pathways 5.) Effector organs (heart, arterioles, and venules/veins
what is “effective circulating blood volume”
pressure in the system (blood pressure) that drives perfusion to the tissues
Response of hypothalamus to decreased arterial pressure
sends inhibitory signals to the nucleus ambiguous (cardioinhibitory center) and decreases vagal output
Aortic baroreceptor afferents
carried in the aortic nerve via the vagus nerve (CN X)
cardiostimulatory center
tonically active. Controls the sympathetic output of the heart (SA and AV nodes and ventricular myocardium)
define regultaion
maintanance at a CONSTANT level - the ability of the body to keep arterial pressure constant in the face of stress (eg: changes in body position or exertion)
