Blood Vessels and Circulation

Flashcards on Blood Vessels and Circulation

Pulmonary Circuit

Blood flows from the right ventricle to the pulmonary arteries, gas exchange occurs in the lungs, and blood returns to the left atrium via the pulmonary veins.

Systemic Circuit

Blood flows from the left ventricle to systemic arteries, reaches the head, neck, and upper limbs via capillaries, and returns to the right atrium via systemic veins.

Tunica Intima (Interna)

Innermost layer of blood vessel walls, composed of endothelial cells, connective tissue, and elastic fibers.

Tunica Media

Middle layer of blood vessel walls, containing concentric sheets of smooth muscle.

Tunica Externa (Adventitia)

Outermost layer of blood vessel walls, a connective tissue sheath that anchors the vessel to surrounding tissues.

Continuous Capillaries

Have a complete endothelial lining and allow passage of small molecules.

Fenestrated Capillaries

Contain fenestrations (pores) that permit rapid exchange of water and solutes.

Sinusoids

Resemble fenestrated capillaries but have larger gaps between adjacent cells.

Capillary Beds

Interconnected networks of capillaries supplied by more than one artery via collaterals.

Arteriovenous anastomosis

Directly connects arteriole to venule, bypassing the capillary bed.

Vasomotion

Cyclic contraction and relaxation of precapillary sphincters.

Valves (in veins)

Prevent backflow of blood in veins.

Contraction of Skeletal Muscles (for venous return)

Contraction compresses veins, aiding in blood flow against gravity.

Venoconstriction

Contraction of smooth muscle fibers in veins to maintain blood volume in the arterial system.

Cardiovascular Regulation

Adjustments to cardiac output and blood distribution within systemic and pulmonary circuits.

Peripheral Resistance

Resistance of the arterial system.

Venous Return

Amount of blood arriving at the right atrium each minute.

Vascular Resistance

Opposition to blood flow in vessels, resulting from friction between blood and vessel walls.

Viscosity (of blood)

Resistance to flow caused by interactions of solutes and suspended materials in a liquid.

Turbulence (in blood flow)

Type of fluid flow with eddies and swirls, caused by high flow rates, irregular surfaces, and sudden changes in vessel diameter.

Pressure Gradient

Difference in pressure from one end of a vessel to the other.

Pulse Pressure

Difference between systolic and diastolic pressure.

Mean Arterial Pressure (MAP)

Adding 1/3 of pulse pressure to diastolic pressure; estimates average blood pressure.

Diffusion

Net movement of substances from an area of higher concentration to lower concentration.

Net Filtration Pressure (NFP)

Difference between capillary hydrostatic and blood colloid osmotic pressure (CHP – BCOP).

Vasodilators

Local chemicals that increase blood flow in capillary beds.

Baroreceptor Reflexes

Respond to changes in blood pressure; located in walls of carotid sinuses, aortic sinuses, and right atrium.

Chemoreceptor Reflexes

Respond to changes in blood and cerebrospinal fluid; monitor CO2, pH, and O2 levels.

Natriuretic peptides (ANP and BNP)

Increased Na+ and water loss in urine, reduced thirst, and peripheral vasodilation; released by the heart in response to high blood pressure.

Umbilical Arteries

Carry blood from the fetus to the placenta.

Umbilical Vein

Carries blood from the placenta to the fetus.

Ductus Venosus

Vascular connection to veins within the liver in fetal circulation; empties into inferior vena cava.

Foramen Ovale (Interatrial Opening)

Allows blood to pass from right atrium to left atrium in fetal circulation.

Ductus Arteriosus

Bypass between pulmonary trunk and aorta in fetal circulation; sends blood from right ventricle to systemic circuit.