CVS

what are the 3 types of blood vessels the cardiovascular system has?

1. arteries (and arterioles), which carry the blood away from the heart

2. capillaries, which is where nutrient and gas exchange occurs

3. veins (and venules), which carry the blood towards the heart

what is the largest artery?

the aorta

what odes the middle layer of an artery wall consist of?

smooth muscle that can constrict to regulate blood flow and blood pressure

what are arterioles capable of?

they can constrict or dilate, changing blood pressure

how thick are capillaries?

they are only one cell thick to allow exchange of gases and nutrients with tissue fluid

where are capillary beds present?

in all regions of the body, but not all of them are open at the same time

what does contraction of a precapillary sphincter muscle do?

it closes off a capillary bed, which when closed, blood flows through an arteriovenous shunt that will bypass the capillary bed

what can drain blood from capillaries?

venules, which then join to form veins that take blood to the heart

how do veins differ from arteries in composition?

they contain much less smooth muscle and connective tissue

what do veins often contain?

valves, which prevent the backward flow of blood

veins carry how much of the body’s blood?

about 70%, and act as a reservoir for blood during injury

what is the heart?

a cone-shaped, muscular organ that is located between the lungs, behind the sternum

what is the heart wall mainly made of?

the myocardium, with tightly interconnected cells of cardiac muscle tissue

what is the pericardium?

the outer, membranous sac with lubricating fluid

how many chambers does the heart have?

four: two upper, thin-walled atria and two lower, thick-walled ventricles

what is the septum?

a wall dividing the right and left sides of the heart

where are atrioventricular valves present?

between the atria and ventricles, with the tricuspid valve on the right and the bicuspid valve on the left

what are both valves reenforced by?

chordae tendinea, which are attached to muscular projections within the ventricles

how does the passage of blood through the heart occur?

it follows this sequence: superior vena cava and inferior vena cava, right atrium, tricuspid valve, right ventricle, pulmonary semilunar valve, pulmonary trunk (pulmonary arteries) carry blood to the lungs, while pulmonary veins carry oxygenated blood away from the lungs, which then goes through the left atrium, bicuspid valve, left ventricle, aortic semilunar valve and then to the aorta, which distributes oxygenated blood to the body

the pumping of the heart sends blood under what?

under pressure to the arteries

where is blood pressure greatest?

in the aorta

what is thicker: the wall of the left or right ventricle, and why?

the left ventricle is thicker than the right, as it pumps blood to the entire body, not just the lungs

when does the blood pressure decrease?

as the cross-sectional area of the arteries, and then the arterioles, increases

what is each heartbeat called?

a cardiac cycle

what occurs when the heart beats?

first, the two atria contract, then, the two ventricles contract, and then, the entire heart relaxes

what is the contraction of the heart chambers?

systole

what is the relaxation of the heart chambers?

diastole

what is responsible for the heart sound, “lup-dup”?

it is due to the closing of the atrioventricular valves, followed by the closing of the semilunar valves

what is the SA (sinoatrial) node?

also known as a pacemaker, it is what initiates the heartbeat (sends out stimulus), causing the atria to contract on average, every 0.85 seconds

what is the atrioventricular (AV) node?

it conveys / receives the stimulus and initiates contraction of the ventricles

where does the signal for the ventricles contract travel through?

it travels through the AV node through the atrioventricular bundle to the smaller Purkinje fibers

what is responsible for the extrinsic control of the heartbeat?

a cardiac control center located in the medulla oblongata, which speeds up or slow down the heart rate, which is regulated by the autonomic nervous system branches

what autonomic nervous system branch slows the heart rate down?

the parasympathetic system

what autonomic nervous system branch increases the heart rate?

the sympathetic system

what hormones can stimulate faster heart rate?

epinephrine and norepinephrine

what is an electrocardiogram (ECG)?

a recording of the electrical changes that occur in the myocardium during a cardiac cycle

what wave does atrial depolarization create?

the P wave

what wave does the ventricle depolarization create?

the QRS wave

what wave does the repolarization of the ventricles create?

the T wave

how many circuits does the cardiovascular system contain?

1. pulmonary circuit

2. systematic circuit

what circulates the blood throughout the lungs?

the pulmonary circuit

what circulates the blood to the rest of the body?

the systemic circuit

what are both circuits vital for?

homeostasis

what is the pathway of the pulmonary circuit?

it starts with the pulmonary trunk from the right ventricle, which branches into two pulmonary arteries, which take deoxygenated / oxygen poor blood to the lungs. in the lungs, the oxygen diffuses into the blood and the CO2 diffuses out of the blood, to be expelled by the lungs

what returns oxygen-rich blood to the left atrium?

four pulmonary veins

what is the pathway of the systemic circuit?

it begins with the aorta carrying O2 rich blood from the left ventricle. the aorta then branches into arteries, each supplying to a specific organ or region of the body.

what do arteries typically divide into?

arterioles, which then branch into capillaries, which lead into venules

for most organs and body regions, the artery that supplies blood and the vein that drains blood share what?

they share the same name

in an adult systemic circuit, what do the arteries carry?

blood that is relatively high in O2, and relatively low in CO2

in an adult systemic circuit, what do the veins carry?

blood that is relatively low in O2, and relatively high in CO2

what is the systemic circuit the reverse of?

the pulmonary circuit, as the pulmonary arteries carry blood high in CO2 and low in O2 and pulmonary veins carry blood that is high in O2 and low in CO2

what do the coronary arteries supply?

the supply the heart muscle (myocardium) itself. they are the first branch off the aorta

what occurs due to the fact the coronary arteries are so small?

they clog easily, leading to heart disease

what does the hepatic portal system do?

it carries blood rich in nutrients absorbed from digestion in the small intestine to the liver, which then monitors the composition of the blood

why is the beating of the heart necessary to homeostasis?

it creates the pressure that propels blood in arteries and the arterioles

what do the arterioles branch off into?

capillaries, which is where nutrient and gas exchange with tissue fluid occurs

what is flow of blood in the arteries is driven by?

by the pressure generated by the heart’s pumping action

what is systolic pressure?

high pressure observed when the heart expels the blood

what is diastolic pressure?

low pressure that occurs

when do systolic and diastolic pressure decrease?

they decrease with distance from the left ventricle because blood enters more and more arterioles and arteries

why does blood move more slowly in capillaries than arterioles?

there are more capillaries than arterioles, making it move more slowly. this also allows time for substances to be exchanged between the blood and tissues

what is venous blood flow dependent on?

1. skeletal muscle contraction

2. presence of valves in veins

3. respiratory movements

what does compression of veins cause the blood to do?

to move forwards past a valve, which then prevents it from returning backwards

what also assists in the return of the blood?

changes in thoracic and abdominal pressure that occur with breathing

how do varicose veins develop?

when the valves of veins become weak

what causes hemorrhoids (piles)?

they are caused due to varicose veins in the rectum

what is phlebitis?

the inflammation of a vein and can lead to a blood clot and possible death if the clot is dislodged and carried to a pulmonary vessel

what is hemophilia?

an inherited clotting disorder due a deficiency in a clotting factor. bumps and falls cause bleeding in the joints, cartilage degeneration and the resorption of bone can follow

what is the most frequent cause of death related to hemophilia?

bleeding in the brain with accompanying neurological damage