Blood Vessel and Cardiovascular System Notes

what is the cardiovascular system composed of

blood vessels and the heart

what does the cardiovascular system do?

distribute blood, deliver nutrients, and remove wastes

what do veins do?

carry blood back to the heart from various body parts

superior and inferior vena cava

carries blood from the upper (superior) and lower (inferior) bodies to the heart

how is the pulmonary vein different from regular veins?

it carries oxygenated blood from the lungs to the heart

what do arteries do?

carry blood away from the heart to to various body parts

how is the pulmonary artery different from the regular arteries?

delivers deoxygenated blood to the lungs

blood passes from the following loop of vessels moving away from the heart and eventually back to it

heart, artery, arteriole, capillary, venule, vein, back to the heart

blood vessel common features

lumen: the hollow interior through which blood flows

endothelium: the inner lining consisting of simple squamous epithelium

common features of blood vessels

they all have traits that reflect its particular function

layers of veins and arteries

inner layer: endothelium

middle layer: smooth muscle and elastic fibers that allow it to stretch and return to its original shape

outer layer: connective tissue

layers of venules

valve, connective tissue, and endothelium

layers of arterioles

smooth muscle, endothelium

layers of capillaries

endothelium, lumen

arteries

thick, muscular vessels that carry blood away from the heart to body tissues

pulse

pressure wave created by the alternate expansion and contraction of the arteries

moves along the arteries with each heartbeat

the pulse rate is the same as the heart rate

vasoconstriction and vasodilation

vasoconstriction: smooth muscle of the middle layer contracts and the diameter of the lumen narrows, reducing blood flow

vasodilation: smooth muscle of the middle layer relaxes and the diameter of the lumen increases, increasing blood flow

aneurysm

occurs when the wall of an artery is weakened and swells outward

the primary risk is that it will burst, causing blood loss

if it does not burst, then it can form life-threatening clots

arterioles

smallest arteries

the prime controllers of blood pressure (pressure of blood against vessel walls)

serves as gatekeepers to capillary networks, keeping them open or closed

capillaries

microscopic blood vessels connecting arterioles and venules

sites of exchange of materials between the blood and the body cells

what do capillaries do/have?

have walls that are one cell thick

provide enormous surface area for exchange (exchange occurs through endothelial cells across the membranes or through slits between these cells)

blood flows very slowly, allowing more time for the exchange of materials

capillary bed

a network of capillaries servicing a particular area

precapillary sphincter regulates blood flow into it

venules

capillaries merge to form venules the smallest kind of vein

join to form larger veins

veins

carry blood back to the heart

walls have the same three layers as arteries, but they are thinner; also have larger lumens

serve as reservoirs for blood volume

the three mechanisms that move blood (against gravity) to the lower parts of the body to the heart

contraction of skeletal muscles

pressure difference caused by breathing

-expansion of the thoracic cavity during inhalation: lowers pressure and pulls blood toward the heart and increases pressure in the abdominal cavity which squeezes veins and moves blood toward the heart

valves in veins prevent the backflow of blood