The Heart and Blood Vessels Human Bio 2025

Cardiovascular system

the heart and blood vessels are collectively known as this system

Arteries

transport blood away from the heart. thick muscle layers

Arteriole

blood eventually reaches the smallest arteries called…

precapillary sphincter

band of smooth muscle where the an arteriole joins a capillary

Capillaries

smallest blood vessels that arterioles connect. thin walled vessels

Veins

have three layers of tissue, outer two layers are much thinner than those of arteries

Myocardium

middle layer of the heart, mainly cardiac muscle that forms the bulk of the heart, contracts every time the heart beats

atria

two chambers at the top of the heart

ventricles

The two more muscular chambers at the bottom of the heart

septum

a muscular partition that separates the right and left sides of the heart

atrioventricular valves (AV)

prevents blood from flowing back into the atria when the ventricles contract. located between the atria and its corresponding ventricle

Semilunar valves

(pulmonary and aortic) prevent back flow into the ventricles from the main arteries leaving the heart when it relaxes

Aorta

the largest artery

Coronary arteries

the heart's set of blood vessels

systole

period of contraction

diastole

the period of relaxation

Cardiac cycle

entire sequence of contraction and relaxation

Sinoatrial node (SA)

a small mass of cardiac muscle cells located near the junction of the right atrium and the superior vena cava

Atrioventricular node (AV)

muscle fibers in this area are smaller in diameter, causing a slight delay of approx. 0.1 second, the delay gives atria time to contract and empty

Purkinje fibers

smaller fibers that carry the impulse to all cells in the myocardium of the ventricles

Electrocardiogram

a record of the electrical impulses in the cardiac conduction system

systolic pressure

pressure reached during ventricular systole when ventricles contract to eject blood from the heart

diastolic pressure

occurs during ventricular diastole when ventricles relax

Hypertension

blood pressure that is higher than normal (high risk factor for cardiovascular disease)

baroreceptors

regulate arterial blood pressure in regions of the large arteries such as the two carotid arteries and aorta.

Cardiac output

the amount of blood that the blood pumps through the aorta each minute

Heart attack

sudden death of an area of heart tissue due to oxygen starvation

Heart failure

if the heart muscle becomes damaged for any reason , the heart can become weakened and less efficient at pumping blood

Congestive heart failure

heart begins to pump less blood, blood backs up in veins and pressure in veins and capillaries rises (Congestion of interstitial fluid)

Stroke

damage to part of the brain caused by an interruption to its blood supply