Nervous Regulation and Renal Control of Arterial Pressure

This set of practice flashcards covers the nervous and renal mechanisms involved in the regulation of arterial blood pressure, including autonomic reflexes, capillary fluid shifts, and the renin-angiotensin system.

The long-term regulation of arterial blood pressure is the dominant role of the __________.

Kidney

Rapid control of arterial pressure is primarily regulated via the __________ nervous system.

autonomic

Short-term regulation of blood pressure involves mechanisms like the baroreceptor reflexes and atrial regulation, which act within __________.

seconds or minutes

Capillary fluid shift is considered a(n) __________ mechanism of arterial blood pressure regulation.

intermediate

The major purpose of the circulatory system is to bring __________ and nutrients to body tissues.

oxygen

Exchange of substances between blood and surrounding tissue occurs in the smallest blood vessels called __________.

capillaries

Lipid-soluble substances and gases move between the blood and tissues through the process of __________.

Diffusion

Large molecules in vesicles are transported through endothelial cells by endocytosis and exocytosis in a process called __________.

Transcytosis

Fluid and blood solutes are driven out of capillaries by __________ forces.

hydrostatic

The osmotic (oncotic) pressure ($P_O$) in blood is generated by differences in __________ concentration between the blood and interstitial tissues.

protein

Hydrostatic force ($P_H$) is defined as the pressure of the fluid in a(n) __________.

closed space

Inside capillaries, the hydrostatic force is essentially the same as capillary __________.

blood pressure

Blood has a higher protein content than interstitial fluid mainly due to the protein __________.

albumin

At the arterial end of a capillary bed, the hydrostatic force ($P_H$) is __________ than at the venous end.

higher

The net outward filtration pressure at the arterial end of a capillary is approximately __________.

$$13\,mmHg$$

The net inward reabsorption pressure at the venous end is approximately __________.

$$7\,mmHg$$

About __________ percent of the fluid is left in the tissues after capillary exchange.

$$15\%$$

Fluid left in tissues after capillary exchange is picked up by the __________ system.

lymphatic

__________ refers to the abnormal accumulation of excess fluid in a tissue.

Edema

Increased filtration causing edema can be caused by increased blood pressure or increased capillary __________.

permeability

Decreased reabsorption leading to edema is often caused by reduced blood __________ levels.

albumin

Obstruction of __________ drainage is a major cause of tissue swelling or edema.

lymphatic

Severe edema may lead to circulatory __________ due to critically reduced blood volume.

shock

The __________ nervous system is important in control of circulation and markedly increases heart rate and pumping strength.

Sympathetic

The parasympathetic nervous system controls heart rate by way of __________ nerve fibers to the heart.

Vagus

Sympathetic nerve fibers innervate almost all vessels EXCEPT __________ and precapillary sphincters.

capillaries

Vascular resistance is increased when sympathetic nerves stimulate small arteries and __________.

arterioles

Sympathetic vasoconstrictor fibers are most densely distributed in the kidneys, gut, spleen, and __________.

skin

Sympathetic vasoconstrictor distribution is notably less potent in the brain and the __________ circulation.

coronary

Arterial Pressure ($AP$) is calculated as the product of Cardiac Output ($CO$) and __________ ($TPR$).

Total Peripheral Resistance

The __________ (VMC) is located in the reticular substance of the medulla and the lower third of the pons.

Vasomotor Center

Continuous signals from the VMC vasoconstrictor area maintain a partial state of contraction in vessels called __________.

vasomotor tone

The __________ portions of the VMC increase heart rate and contractility.

lateral

The __________ portion of the VMC transmits signals via the vagus nerve to decrease heart rate.

medial

The primary neurotransmitter for sympathetic vasoconstrictor nerves is __________.

norepinephrine

The adrenal medulla secretes epinephrine and norepinephrine to constrict vessels via __________ receptors.

alpha-adrenergic

Vessels can be dilated by epinephrine through the activation of __________ receptors.

$$Beta_2$$

__________ syncope occurs when emotional stress triggers a vasodilator reaction and loss of consciousness.

Vasovagal

During vasovagal syncope, there is a decrease in sympathetic output and an increase in __________ output.

vagal

The Vasomotor Center can increase arterial pressure within seconds by constricting arterioles to increase __________.

total peripheral resistance

Rapid increases in arterial pressure can occur during exercise or with __________.

fear

The __________ reflex is initiated by stretch receptors located in the walls of large systemic arteries.

baroreceptor

Baroreceptors are located specifically in the __________ and in the walls of the aortic arch.

carotid sinus

Signals from the carotid sinus are sent via __________'s nerve to the glossopharyngeal nerves.

Hering

All baroreceptor signals eventually reach the __________ (NTS) of the medulla.

nucleus tractus solitarius

Aortic arch signals are transmitted to the NTS through the __________ nerve.

vagus

Carotid sinus baroreceptors are responsive to pressure changes between $60$ and __________.

$$180\,mmHg$$

The baroreceptor reflex is most sensitive when the arterial pressure is around __________.

$$100\,mmHg$$

Increase in carotid sinus impulses leads to inhibition of the vasoconstrictor area and activation of the __________ center.

vagal

Moving from a supine to a standing position causes a decrease in central blood __________.

volume

Maintenance of constant pressure during changes in body posture is a primary function of __________.

Baroreceptors

Chemoreceptors are cells sensitive to oxygen lack, $H^+$ ion excess, or __________ excess.

$$CO_2$$

Chemoreceptors are located in __________ bodies and on the arch of the aorta.

carotid

Activation of chemosensitive receptors results in the __________ of the vasomotor center.

excitation

Chemoreceptors are generally not stimulated until arterial pressure falls below __________.

$$80\,mmHg$$

The __________ response is triggered by reduced cerebral blood flow and $CO_2$ buildup.

CNS Ischemic

The CNS ischemic response is one of the most powerful activators of the __________ system.

sympathetic vasoconstrictor

CNS Ischemic response activation typically starts when pressure falls below __________.

$$60\,mmHg$$

The greatest activation of the CNS Ischemic response occurs at pressures between __________.

$$15-20\,mmHg$$

Prolonged CNS ischemia eventually causes a(n) __________ effect on the vasomotor center.

depressant

Low-pressure receptors in the atria and pulmonary arteries act as __________ sensors.

volume

Activation of low-pressure receptors increases sodium and water excretion by decreasing the rate of __________.

ADH

Low-pressure receptors increase the __________ (GFR) to reduce blood volume.

glomerular filtration rate

The __________ reflex, or atrial reflex, signals the brainstem to increase heart rate when blood volume stretches the atria.

Bainbridge

Increased heart rate during an atrial reflex accelerates blood flow to the __________ to promote fluid filtration.

kidneys

Stretching of the atria leads to the release of __________ (ANP), which causes vasodilation of renal vessels.

Atrial Natriuretic Peptide

Infusing $500\,mL$ of fluid into a person will decrease __________ hormone (vasopressin) levels via the hypothalamus.

ADH

The __________ node can be stretched during increased atrial volume, leading to a higher heart rate.

SA

ADH is secreted by the __________ in response to increased blood osmolarity.

posterior pituitary

The action of ADH is to promote __________ by the kidney tubules.

water reabsorption

Long-term control of blood pressure is determined by the __________ system (RAS).

renin-angiotensin

Increased extracellular fluid volume elevates arterial pressure by increasing cardiac output or __________.

total peripheral resistance

The phenomenon where rising arterial pressure increases urine volume output is called __________.

pressure diuresis

Pressure __________ is the increased output of sodium that occurs alongside pressure diuresis.

natriuresis

Urine output is essentially zero when the arterial pressure falls to __________.

$$50\,mmHg$$

Urine output is considered normal at an arterial pressure of __________.

$$100\,mmHg$$

At $200\,mmHg$, urine output is about __________ times normal.

six to eight

Sodium is the main __________ in the extracellular fluid bathing all cells.

cation

Sodium concentration determines the __________ of the extracellular fluid.

osmolality

The enzyme __________ is released by the kidney when arterial pressure decreases.

renin

Renin acts on angiotensinogen, also known as renin __________, to form Angiotensin I.

substrate

Angiotensin I is converted to Angiotensin II by converting enzyme located in the __________.

lung

Angiotensin II increases arterial pressure through vasoconstriction and __________.

renal retention of salt and water

Excess salt stimulates the __________ center in the brain, increasing fluid intake.

thirst

Excess salt stimulates the hypothalamic-posterior pituitary to secrete __________, decreasing urine excretion.

ADH

When the RAS is blocked, a fifty-fold increase in salt intake can cause pressure to rise by __________.

$50$ to $60\,mmHg$

With a normal RAS, a fifty-fold increase in salt intake only raises pressure by about __________.

$4$ to $6\,mmHg$

The first priority of the pressure control system after severe bleeding is __________.

survival

The second priority after bleeding is to return __________ and arterial pressure to normal levels.

blood volume

Increased central venous pressure leads to atrial stretch and signals the VMC via __________ afferents.

vagal

Renin is a component of the __________ pathway.

RAAS

The adrenal medulla secretes __________ and norepinephrine as part of the sympathetic response.

epinephrine

Cerebral __________ causes a buildup of $CO_2$, which strongly stimulates the VMC.

ischemia

Total peripheral resistance is increased by the constriction of almost all __________ of the body.

arterioles

Atrial stretch increases heart rate and __________.

contractility

The integrated system for pressure regulation uses both nervous and __________ mechanisms for control.

hormonal