Circulation 3

what is the textbook definition of blood pressure

force per area exerted on blood vessels by blood

what is exerting force onto what to determine blood pressure

blood exerting force onto blood vessels

mean filling pressure

a passive component that reflects average vessel filling

when does mean filling pressure occur

after the heart stops

what effect does active pumping of blood have on arterial pressure and venous pressure

increases arterial pressure

Reduces venous pressure below mean filling pressure

equation for pressure

P = flow * resistance

what is the homeostatic MAP

95 mmHg

what kind of sensors are present in the kidney

volume and flow

where are high pressure baroreceptors located

aorta

carotid artery

where are low pressure sensors located

atria

pulmonary vessels

where are chemoreceptors found

aorta and carotid artery

identify the long term volume modifying hormone systems

renin-angiotensin-aldosterone

ADH

atrial naturetic factor

short term hormone systems for arterial pressure

catecholamines

angiotensin II

ADH (vasopressin)

afferent nerves of the baroreceptor system

Hering's nerve (carotid sinus nerve)

glossopharyngeal nerve (CN IX)

vagus nerve (CN X)

where is baroreceptor information sent to

medullary vasomotor centor

efferents of the baroreceptor system

sympathetic nerves

vagus nerve

what are the effectors of the baroreceptor system

blood vessels

heart

what do peripheral chemoreceptors detect

O2

CO2

pH

when does baroreceptor firing rate increase

in response to increased stretch (due to arterial pressure)

sympathetic activity of the baroreceptor response influences which variables

alpha1 activation (vasoconstriction)

beta1 activation (contractility)

what does parasympathetic activity in the baroreceptor reflex control

muscarininc receptor activation (HR)

what do chemoreceptors regulate

ventilation (primarily)

HR

CO

SVR

what are the cutoffs for stimulation of chemoreceptors

pO2 <95

pCO2 >40

ph <7.4

when pO2 decreases, sympathetic outflow to the _ is increased

skin

where are glomus cells found

carotid bodies

what do glomus cells release

dopamine

acetylcholine

ATP

adenosine

what are the receptors for low pressure

mechanoreceptors on vagal fibers

atrial myocytes

where does output from vagal fibers in the atria/pulmonary vessels go

medulla

effects of stimulation of pressure sensors in carotid sinus/aortic body

increased sympathetic activity to the SA node

inhibition of sympathetic nerves to renal arterioles

inhibit pituatary ADH release

what is the bainbridge reflex

acceleration of HR signaled by increased stretch of atrial baroreceptors

what do atrial myocytes release

atrial naturetic peptide (ANP)

effects of ANP

increase water and sodium excretion (natriuresis)

suppress sympathetic activity

decreased thirst

down regulate kidney renin-angiotensin-aldosterone

ANP acts on which organs

kidney and brain

ANP is released in response to _

atrial stretch (associated with high BP

what is natriuresis

excretion of sodium and water from the kidney via reabsorption

effect of ANP

reduced cardiac output and systemic arterial BP

ANF does NOT do what

vasodilation (it does it indirectly via inhibition of sympathetic)

which are the volume modifying hormone systems

renin angiotensin aldosterone

ADH

ANF

how does ANF affect the hypothalamus

less ADH secretion

less thirst

how does ANF affect kidney

increase sodium and water excretion

reduce renin secretion

increased glomerular filtration (vasodilation of afferent arteriole)

pulmonary blood flow is equal to

systemic blood flow and cardiac output

average pressure difference between the left atrium and pulmonary artery

10 mm Hg

a low pressure and resistance pathway of pulmonary circulation has what effect

reduces possibility of pulmonary edema

pulmonary vascular resistance is _ compared to systemic vascular resistance

less

how does pulmonary vascular resistance change as cardiac output increases

decreases

how does pulmonary vascular resistance decrease in response to increased CO

recruitment and distension of capillary beds

venous return _ during inspiration

increases

which pressure is highest in zone 1 of the lungs

alveolar pressure

which pressure is highest in zone 2 of the lungs

arterial pressure

where is blood flow lowest in the lungs (and why)

apex; due to the effects of gravity

blood flow in zone 3 of the lungs depends on what

the pressure difference between pulmonary artery and vein

pressure gradient relationship in zone 1 of the lungs

alevolar > arterial > venous

pressure gradient relationship in zone 2 of the lungs

arterial > alveolar > venous

where is ventilation greatest in the lung

base of the lung

how is fluid balance maintained in pulmonary capillaries

pulmonary capillary hydrostatic pressure is less than plasma colloid osmotic pressure (less filtration)

what causes an increase in pulmonary capillary pressure

left ventricular failure

main regulator of pulmonary blood flow

low alveolar pO2 causes vasoconstriction

the aortic baroreceptors send their signals via

vagus nerve

pulmonary vascular resistance decreases by _ mechanisms in response to _

passive; increased arterial pressure

how is cardiac output affected by activation of the baroreceptor reflex

decreased

what effect does vasoconstriction in pulmonary flow

re-directs blood to better-ventilated segments

fluid balance in pulmonary capillaries favors _

reabsorption

_ of blood flow in the brain is very strong

autoregulation

what is the most powerful regulator of brain blood flow

CO2 (metabolic)

what causes local variations of blood flow in the brain

neuronal activity

there is minimal _ influence on cerebral brain flow

neurogenic

how does pCO2 affect cerebral blood flow

low pCO2 = vasoconstriction

high pCO2 = vasodilation

afferent kidney arterioles feed into

glomerular capillaries embedded in Bowman's capsule

high blood flow through the kidney is related to _

kidney function

intrinsic regulation method of the kidney flow

myogenic autoregulation of the afferent arteriole

extrinsic regulation of kidney blood flow

sympathetic innervation

antagonism by ANF

angiotensin II

three components of hormone control of blood pressure

arteriole tone control

blood volume control (ADH, renin, ANF)

cardiac output control

what effect does angiotensin II have on kidney

constricts efferent arteriole to reduce renal blood flow

what does splanchnic circulation supply

stomach

spleen

intestine

pancreas

liver

branches of the aorta associated with splanchnic circulation

celiac artery

superior mesenteric artery

inferior mesenteric artery

what delivers most of the blood flow to the liver

hepatic portal circulation

dominant regulation of the splanchnic circulation

sympathetic innervation

blood from _ flows into the liver via the _

gut

spleen

pancreas

(portal vein)

how does blood leave the liver

via the hepatic veins

what lines the liver sinusoids

reticuloendothelial cells

what allows the liver to filter blood

reticuloendothelial cells that line the sinusoids

what drains into the portal vein

blood from the gut, spleen, pancreas

_ skin contains hair

nonapical

which type of skin lacks hair

apical skin

apical skin has a rich _

vascular supply with AV shunts

apical skin is under control of what

sympathetic innervation

what happens to apical skin during cold temperature

sympathetic nervous system stimulates vasoconstriction (to reduce heat loss)

the placenta consists of

fetal placenta

maternal placenta

3 major fetal circulatory shunts

ductus venosus

foramen ovale

ductus arterosus

the ductus venosus carries what

oxygenated blood to the fetal heart

which veins empty directly into the ventricles

thebesian

primary control of flow to the heart is through

metabolic factors

ANS factors secondary

when is left ventricular coronary flow minimal and maximal

minimal: systole

maximal: diastole

what is unique about coronary circulation

the heart perfuses itself

overall driving pressure for coronary perfusion

pressure difference between the aorta and the right atrium

what counteracts coronary blood flow

ventricular contraction

how are coronary blood flow and aortic pressure related

direct relationship

major determinants of cardiac oxygen consumption

HR

wall tension

contractility

sympathetic effect on coronary blood flow

increases cardiac blood flow

increase HR

increase contractility

oxygen extraction is _ in coronary circulation

high