Cardiovascular system

Cardiovascular system

A closed system of the heart and blood vessels.

Heart Size

The heart is about the size of a human fist and weighs less than a pound.

Pericardium

A double-walled sac that covers the heart.

Epicardium

The outside layer of the heart wall; also known as visceral pericardium.

Cardiac cycle

One complete heartbeat in which both atria and ventricles contract and then relax.

Troponin

A protein involved in the contraction of cardiac muscle.

Cardiac output (CO)

Amount of blood pumped by each side (ventricle) of the heart in one minute.

Stroke volume (SV)

Volume of blood pumped by each ventricle in one contraction/heartbeat.

Heart rate (HR)

Number of heartbeats per minute.

Tachycardia

Rapid heart rate, over 100 beats per minute.

Bradycardia

Slow heart rate, less than 60 beats per minute.

Systolic pressure

Pressure in the arteries at the peak of ventricular contraction.

Diastolic pressure

Pressure in the arteries when the ventricles relax.

Blood pressure (BP)

The pressure blood exerts against the inner walls of blood vessels.

Coronary arteries

Branch from the aorta and supply the heart muscle with oxygenated blood.

Intrinsic conduction system

Sets the heart rhythm; consists of specialized conducting tissue.

Pulmonary trunk

Carries oxygen-poor blood from the right ventricle to the lungs.

Aorta

Carries oxygen-rich blood from the left ventricle into systemic circulation.

AV valves

Valves that allow blood flow between the atria and ventricles.

Semilunar valves

Valves that prevent backflow from the arteries into the ventricles.

Capillary beds

Main sites of exchange between blood and tissues.

Osmotic pressure

Draws fluid into capillaries.

Blood Flow Pathway

Right ventricle → Pulmonary trunk → Pulmonary arteries → Lung capillaries → Pulmonary veins → Left atrium.

Precapillary sphincters

Guard the entrances to capillary beds.

Fetal shunts

Allow fetal blood to bypass the lungs and liver before birth.

Hepatic portal vein

Carries blood from digestive organs to the liver.

Age-related cardiovascular problems

Include weakening of venous valves and progressive arteriosclerosis.