vasculature and blood pressure (anatomy)

majority of systemic blood volume is in the venous or arterial circulation (at rest)

venous circulation

veins are less muscular then arteries. True or false?

true

capillaries cannot constrict or dilate. True or false?

True

what is the role of precapillary sphincters?

adjust blood flow into the capillaries

what is a capacitance vessel

vein. due to its thin walls high high degree of expansion and a large amount of room for blood "storage"

venous reservoirs

due to the large capacity of veins and accompanying valves. some venous blood pools into veins

blood flow is determined by (2 things)

pressure and resistance

normal systolic is between ____-____ mmHg

100-130 mmHg

normal diastolic pressure is between ____-____mmHg

65-80mmHg

What is pulse pressure?

difference between systolic and diastolic pressure

Why do veins not have a pulse?

due to low pressure and low elastic recoil of the veins

blood pressure is ultimately affected by what 3 things

cardiac output, peripheral resistance, blood volume

3 things that contribute to peripheral resistance

- blood viscosity

- vessel length

- vessel diameter

3 "controls" that control vessel diameter?

Local, neural, hormonal

how do vessels (arteries) react to increase in CO2 and lactic acid? (hypoxia)

they vasodilate (increasing the perfusion)

Nitric oxide is a

vasodilator

Endothelin is a strong vaso(dilator/constrictor)?

vasoconstrictor

protsaglandins are a vaso(dilator/constrictor)?

vasodilators

What is reactive hyperemia?

localized vasodilation

the vasomotor center is located in the?

medulla

what is the function of the vasomotor center

send sympathetic signals to smooth muscle of arterioles venules, and veins of "blood reservoirs"

what happens when acute increases in BP are detected by the aortic and carotid baroreceptors?

send signals to the vasomotor center that inhibits the vasoconstrict centers so that parasympathetic control is dominate and causes vasodilation

what happens when acute decreases in blood pressure is detected by the carotid and aortic baroreceptors?

stimulation of vasoconstrictor center sympathetic control dominates and causes vasoconstriction

what happened to reservoir vessels during acute decrease in Bp and sympathetic response

reservoir vessels constrict and cause venous return to be increased

stimulation of peripheral chemoreceptors by hypercapnia and decreases in PH and hypoxia stimulate _________ centers what happens to the reservoir vessels?

vasoconstriction centers. reservoir vessels constrict and increase venous return

what is the medullary ischemic reflex?

acute ischemia to the medulla cause vasoconstriction in the lower part of the body shunting blood toward the upper body (brain)

how does the "higher brain" control blood pressure?

cerebral cortex and hypothalamus influence vasoconstriction centers, also responsible to thermoregulatory blood shunting

what is a venous pump (respiratory pump)

normal physiological breathing causes blood to be "pulled" through the vena cava and increases cardiac output

how does skeletal muscle increase venous return?

contraction of skeletal muscle (especially int he legs" compresses and squeezes venous blood toward the heart

cardiac suction

what are varicose veins? caused by?

incompetent valves cause blood to pool in the veins and distend and are visible superficially

blood flow is determined by

pressure gradient/resistance

how do large arteries reduce pulsatile flow pattern produced by heart contractions?

less stretching of the vessel wall means there is less rebound and a lower diastolic

What does diastolic pressure represent?

The pressure in the arteries due to the elastic energy of the arteries rebounding back

(stored energy in the elastic tissue of the artery)

what does a widening pulse pressure represent?

increase in pulsatile flow it means that there are less compliant arteries (bad thing for tissues we want constant blood flow tot he tissues)

blood pressure is determined by what 3 things

cardiac output, blood volume, and vascular resistance

peripheral resistance is determined by

blood viscosity

vessel length

vessel diameter (also think turbulent and laminar flow)

what affect would turbulent blood flow have on blood pressure

increases blood pressure

___________ has the biggest effect on vascular resistance

diameter

body response to paper cut?

will release chemicals to vasoconstriction upstream to the damage and reroute blood

localized damage to vessels cause ?

a localized vasoconstriction upstream from the damage

localized vasodilation is generally referred to as?

reactive hyperemia

damaged platelets will release

vasoactive substances

Vasoactive substances

substances that impact the vessel itself (vasoconstriction)

What is toxic (septic) shock syndrome?

certain infections can release endotoxins that cause the body to synthesize nitric oxide and cause widespread vasodilation leading to shock (massive decrease in blood pressure)

the Brain has the most consistent blood flow in the entire body. True or false?

True

where would blood be "shunted" during exercise

skeletal muscle

RAAS

renin-angiotensin-aldosterone system

RAAS will cause what to happen to blood pressure?

increase in blood pressure

higher brain control of blood pressure involves nerve impulses from the __________ and _______ of the brain which influence vasoconstrictor centers

cerebral cortex, hypothalamus

what is thermoregulatory blood shunting

shunting of blood to the periphery to increase heat loss and sweating (hypothalamic control)

what is the respiratory pump

alternating changes in intrathoracic/ intrabdominal pressure enhance venous return (especially in deep breathing) and compression of abdominal muscles squeeze blood to the heart

explain the alternation between intrathoracic pressure and abdominal muscles in breathing in terms of venous return

breathing causes a drop in intrathoracic pressure which pull venous blood toward the heart while compression of the abdominal muscles squeezes/pushes blood toward the hear (they are both working together to achieve the higher venous return

Kidney response to low fluid volume

juxtaglomerular cells secrete renin, renin converts to angiotensinogen at the liver to angiotensin 1 then travels to the lungs and converts to angiotensin 2 by ACE which is a vasoconstrictor. angiotensin 2 stimulates ADH release and then travels to the adrenal glands and stimulates the release of aldosterone which increases water and sodium reabsorption

electrolyte balance has a large impact on fluid volume in the body. True or false?

True

Vasopressin

ADH

Function of ADH (vasopressin)

increase blood pressure by increasing blood volume by increasing water reabsorption at the collecting duct of the kidenys

What secretes ADH?

posterior pituitary

ANP (when is it released? where is it stored? what does it do?)

- stored in the cells of the atria and released when here is stretching (increased preload), decreases renin release, decreases aldosterone, decreases ADH, increases glomerular filtration and causes vasodilation