Cardiovascular System: Blood Flow and Regulation Concepts

Factors assisting venous return

Valves in the veins, sympathetic stimulation, compression of veins by muscular movements.

Primary function of capillaries

The exchange of nutrients and gases between the blood and tissue cells.

Afterload

The arterial pressure that the ventricles must overcome to eject blood.

Location of chemoreceptors sensitive to blood carbon dioxide levels

Medulla oblongata.

Intrinsic regulation of the heart

If cardiac muscle fibers are slightly stretched, they have a stronger contraction force.

Effect of increased preload

An increase in cardiac output and force of left ventricular contraction.

Relationship between preload and stroke volume

Starling Law of the heart.

Mechanism increasing cardiac output during hemorrhagic shock

Increased sympathetic stimulation of the heart.

Movement of blood through the vascular system

Pressure gradients created by the heart.

Order of blood vessels for red blood cell travel

Artery, arteriole, capillary, venule, vein.

Increased blood velocity through the capillaries

The thinness of the capillary wall

Continuous capillaries

Have a wall where the endothelial cells fit very tightly together.

Continuous capillaries

Are more permeable than fenestrated capillaries but not as permeable as sinusoidal capillaries.

Fenestrated capillaries

Most likely found in the kidney.

Sinusoidal capillaries

Have large fenestrae and are found in endocrine glands, in the bone marrow and the liver.

Precapillary sphincters

Control the blood flow into capillary beds.

Correct statement about arteries and veins

Veins contain valves and arteries do not.

Relaxation of the precapillary sphincter

Occurs when the tissue in the area needs more oxygen.

Tunica intima

The coat of an artery that contains endothelium.

Tunica media

The layer of an artery that allows it to constrict or dilate as needed.

Blood vessels under the greatest pressure

Elastic arteries.

Valves similar to the semilunar valves

Found in medium and large veins.

True statement about arteries and veins

Arteries have a thicker tunica media than veins.

Arteries branching from the aortic arch

Brachiocephalic artery.

Blood pressure reading of 120/80

Indicates a systolic pressure of 120 mm Hg.

Blood pressure reading of 120/80

Have Korotkoff sounds at pressures above 120 mm Hg.

Blood pressure reading of 120/80

Indicates a diastolic pressure of 80 mm Hg.

Blood pressure reading of 120/80

Would not be considered hypertensive.

Resistance to blood flow

A decrease in the radius of the vessel.

Resistance in the cardiovascular system

Tends to increase if blood viscosity increases.

Compliance

More easily the vessel wall stretches.

Vessel with greatest compliance

Veins.

Storage area for blood

The veins.

Effect of arteriosclerosis on compliance

Causes the pulse pressure to increase.

Blood pressure vs. blood colloid osmotic pressure

A net movement of fluid out of the capillary.

Force causing fluid movement out of capillary

Blood pressure.

Force attracting fluid into capillary

Blood colloid osmotic pressure.

True statement about capillary exchange

Most fluid that leaves the arterial end of a capillary reenters the venous end of a capillary.

Increased venous tone

Help return blood to the heart.

Effect of standing in one place

All of these choices are correct.

Regulation of local blood flow

Contraction of precapillary sphincters will increase blood flow to a capillary bed.

Increased levels of carbon dioxide

Increase the contraction of precapillary sphincters.

Blood flow through capillaries

Is continuous.

Increased metabolic rate in a tissue

Increases capillary blood flow into the tissue.

Tissue need for oxygen and amino acids

Will cause precapillary sphincters to contract.

Heart rate after an increase in blood pressure

Increases.

Action potential frequency to the cardioregulatory center of brain

Decreases.

Baroreceptors

Are stimulated after an increase in blood pressure.

An increase in number of action potentials in the cardiac nerve

Occurs after an increase in blood pressure.

Sympathetic stimulation of the heart

Increases after an increase in blood pressure.

Baron von Quacko's sleeper hold

Presses on baroreceptors in carotid sinus; causes peripheral vasodilation and decreased heart rate.

Chemoreceptor reflexes

Help maintain homeostasis when carbon dioxide levels increase.

Hormone that does NOT influence blood pressure

Growth hormone.

Angiotensin II

Causes vasoconstriction.

Increased renin release by the kidneys

Results in an increase in blood volume.

Chemical substances causing blood pressure to decrease

Atrial natriuretic hormone.

Response to circulatory shock

The renin-angiotensin mechanism is activated.

Fluid shift mechanism in high blood pressure

Causes water to shift from the capillaries into the interstitial spaces.

Atrial natriuretic factor

Is released in response to elevated atrial pressure.

Aldosterone

Increases blood pressure by retaining Na+ in the kidneys which triggers an increase of water reabsorption and an elevation of blood volume.

Renin

An enzyme that indirectly causes an elevation of blood pressure by activating the RAAS.

Angiotensin 2

A peptide hormone that causes vasoconstriction and an increase in blood pressure, part of the RAAS, and stimulates the release of aldosterone.

ADH

Increases blood volume and blood pressure by causing the insertion of aquaporins in the kidney tubular cells which increases the reabsorption of water.

Atrial natriuretic peptide

A hormone produced and secreted from the cardiac atria in response to increases in blood pressure and stretching of the atrial walls, decreases Na+ reabsorption by the kidneys.

Capillaries

Known as the exchange blood vessels.

Tunica media

The muscular layer of a blood vessel.

Continuous capillaries

Have endothelial cells that provide an uninterrupted lining, allowing smaller molecules like water and ions to pass through.

Sinusoid capillaries

The largest capillaries with an irregular cross section and gaps between endothelial cells, found in the liver, adrenal medulla, and bone marrow.

Fenestrated capillaries

Have a perforated lining with small pores, found in tissues with extensive molecular exchange like the small intestine, endocrine glands, and kidney.

Venous system

Holds the largest percentage of the blood supply.

Blood viscosity

One of the main factors that increase peripheral resistance.

Diffusion

One of the mechanisms that move materials across capillary walls.

Filtration

One of the mechanisms that move materials across capillary walls.

Hydrostatic pressure

When blood colloid osmotic pressure is greater than this pressure, fluid will move into the capillary.

Plasma protein concentration

Decreased levels will elevate the tendency to develop edema.

Peripheral resistance

Increased by factors such as vascular resistance, blood viscosity, and turbulence.