Physiology Lecture 26: Regulation of Vascular system and Blood flow

Neurogenic control

this is the control of regulation of the blood vessels that is through the nervous system and is very FAST

Baroreceptors

these are sensory receptor cells that respond to stretch by increasing their firing rates. These cells are found in the carotid sinuses and on the aortic arch

Local control

this refers to factors taken in or released by the tissues of a given capillary bed. Factors that have important effects on the precapillary sphincters are oxygen levels, CO2 levels, adenosine levels, and lactic acid and H+ levels

Autoregulation

an intrinsic property of the arteriolar smooth muscle layer and the precapillary sphincters. When these smooth muscle cells are stretched they respond by contracting and thereby decrease the diameter of the blood vessels

Parasympathetic

this part of the autonomic nervous sytem only affects the heart by decreasing heart rate , there is little to no control over the vasculature except for facial skin and genitals

acts at the SA and AV nodes and decreases heart rate

when the parasympathetic system does play on the heart, where does it act and what does it cause

Sympathetic control

this part of the autonomic nervous system increases heart rate, but also increases myocardial contractility thus increasing CO. Also affects vasculatorue primarily through vasoconstriction, but some dilation as well

Increase, venous return, increases, increased

Sympathetic stimulation causes an _____________(increase/decrease) in vascular tone, which increases ___________ ___________, it also _____________(increases/decreases) cardiac output, and ______________(increases/decreases) blood pressure due to cardiac output changes and ____________(increased/decreased) vasculature resistance

venous

most of the blood is stored in the _____ system

Mean arterial pressure

Neurogenic control mainly affects ___________ ___________ ____________, and this can happen by decreasing kidney perfusion, decreasing gut and spleen perfusion, and skin perfusion in order to increase it

Vascular tone

the level of smooth muscle contraction at any given time

No precapillary sphincter opening is only controlled at a local level

Does the sympathetic nervous system innervate the precapillary sphincter?

Cardioinhibitory center, increases, reduces, lowers

When baroreceptors increase firing due to eleated blood pressure, it stimulates the ____________________ ____________, which ___________(increases/decreases) parasympathetic tone, which __________(elevates, reduces) heart rate, which in effect ___________(elevates, lowers) blood pressure

Cardioinhibitory system

the area of the medulla which decreases the firing rate of the sympathetic neurons innervating the heart and increases parasympathetic activity in response to the baroreceptors

Vasomotor center

the area of the medulla that controls the firing rate of the sympathetic neurons, and responds usually in regards to baroreceptors

Vasomotor center, reduces, reduces, dilation, decreases

baroreceptors also inhibits the _______________ ____________ which ____________(elevates, reduces) sympathetic innervation, which ____________(elevates reduces) vasomotor tone, which causes vaso_____________(dilation/constriction), which ______________(increases, decreases) blood pressure

increase, increase

The increase of firing from the baroreceptors causes a _______ in sympathetic firing and _____ in parasympathetic firing of neurons controlling the heart and the blood vessels

inhibited

when the baroreceptors are firing, the vasomotor center is (stimulated/inhibited)

stimulated

when the baroreceptors are firing, the cardioinhibitory center is (stimulated/inhibited)

sympathetic, parasympathetic

baroreceptors on the carotid sinuses and aortic arch increase their firing with increased blood pressure. This increased firing causes a decrease in _______ (sympathetic/ parasympathetic) firing, and increase in (sympathetic/parasympathetic) firing of neurons controlling the heart and blood vessels. The opposite happens when blood pressure is low

Hypertension

Prolonged ____________________(what pathology?) causes a reset of the baroreceptors such that their new firing rate is lower at any given pressure, meaning that there needs to be external intervention

Adrenaline (Epi)

_______, released by the adrenal medulla into the circulation has the same effect as stimulating the sympathetic nerves

Antidiuretic hormone

this is a hormone that works on the kidneys, but in effect increases mean arterial pressure with a mild vasoconstrictive effect

increases

ADH increases/decreases water rebsorption

Angiotensin II

this is a hormone that primarily affects the kidneys through aldosterone, and is a very potent vasoconstrictor, and many drugs work by antagonizing this

Atrial natriuretic factor

this hormone is released by the atria when it is stretched and decreases Mean arterial pressure, by increasing the amount of urine volume

mild

how much of a vasoconstrictive effect does ADH have?

very potent vasoconstritor

how much of a vasoconstrictive effect does Angiotensin II have?

Kidney

most hormones (except for adrenaline) affect mean arterial pressure by affecting blood volume through actions of the ______________

precapillary sphincters

vascular beds control the amount of blood flow by regulating the _____ ______

CO2

When active cells use O2 to make ATP, they produce ______ as a biproduct

Acidic

The increase of CO2 causes the intracellular and extracellular space to become more ____________(acidic/basic)

Relax

When the increased acidity happens, the smooth muscle will ___________(contract, relax)

Adenosine

When there is not sufficient O2, the hormone ________________ is released from the active cells

Relaxation, dilation, increase

Adenosine acts by causing the _______________(constriciton/relaxation) of the vasculature, causing vaso_____________(constriction/dilation), which ___________(increases/decreases) blood flow

contract, increase, increase, decrease

When o2 levels are high due to low activity, the precapillary sphincters can ________________, which causes the diameter of the vessels to ____________(increase/decrease) and causes a _________________(increase/decrease) in resistance, and a _____________(increase/decrease) in blood flow

Decrease, hyperpolarization, dilate, increased

When there is high activity (like high CO2, K+, adenosine, H+), they activate Katp channels to _____________(increase/decrease) L type Ca channel activity, which leads to ___________________(depolarizaiton/hyperpolarization) and the smooth muscle _______________(constricts/relaxes), and the vessels ____________(constrict/dilate), causing ____________(increased/decreased) blood flow

vasodilation

Adenosine, K+, low pH cause ______

vasoconstriction

higher pH and oxygen tension cause ________

increases, relax

adenosine ______ the levels of cAMP in vessel smooth muscles causing them to ____ (MLCK inhibition by PKA)

Contracting

Vessel smooth muscle can react to stretching by _______________ against the stretch

Hyperpolarize, increases

Vessel smooth muscle can ________________ if not stretched enough, which _____________(increases/decreases) blood flow

Hyperemia

redness of the skin due to increased blood flow

Cerebral circulation

this type of circulation is primarily regulated through autoregulation

Stable

The blood flow in the brain is very _________, because the blood flow is determined by local factors like CO2 through autoregulation, even though the pressures in the brain are vastly different

Cardiac circulation

this is the way that the heart receives nutrients and gas exchange via vasculature

Diastole

The heart is the only major organ that is perfused during ______________

Compressed, small

The heart gets perfused during diastole because during systole, the muscle is ________________, and the arterial diameters are ____________(big/small)

high

During diastole in the heart, the coronary arterioles are supplied with blood due to _________(high/low) aortic pressure

Aortic

The coronary arteries open to the aorta next to the ___________ valve in the coronary cusps of the valve

Systolic compression

the compression of the myocardium during systole which decreases blood flow to the heart. Most of the cardiac blood flow occurs during diastole when the myocardium is not compressed