Circulatory System Overview

A three-chambered heart is found in reptiles, while mammals and humans have a four-chambered heart. The heart chambers help pump blood throughout the body.

The circulatory system is responsible for carrying oxygen-rich blood to cells and waste products away from cells. It also transports hormones, regulates body temperature, and helps fight infections.

Blood vessels are tubes that carry blood throughout the body. There are three types: arteries, veins, and capillaries.

Arteries are thick-walled blood vessels that carry oxygenated blood away from the heart. They have smooth muscle that allows them to dilate or constrict to regulate blood flow.

A pulse is the rhythmic throbbing of blood in an artery, created as blood flows through the vessel. Blood pressure is the pressure of blood in an artery as the heart contracts.

Capillaries are the smallest blood vessels with thin walls, only one cell thick. They allow for the exchange of oxygen, nutrients and waste products between the blood and cells.

A precapillary sphincter is a ring of smooth muscle that regulates blood flow into capillaries.

Capillaries are involved in diffusion and osmosis, allowing oxygen and nutrients to move into tissues and waste products to move into the blood.

Veins are thin-walled blood vessels that carry deoxygenated blood back to the heart. They contain valves that prevent backflow of blood.

The flow of blood through the circulatory system follows a specific pattern: arteries, arterioles, capillaries, venules, veins.

Veins have a lower blood pressure compared to arteries. Special mechanisms like valves and skeletal muscle contractions help return blood to the heart.

Vasodilation is the widening of blood vessels, while vasoconstriction is the narrowing of blood vessels. Both actions help regulate blood flow and temperature.

The heart is a muscular organ the size of a fist, responsible for pumping blood throughout the body.

The heart is divided into two sides (left and right) by a muscular wall called the septum. Both sides work simultaneously.

The heart is primarily composed of cardiac muscle tissue, found only in the heart.

The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs. The left side receives oxygenated blood from the lungs and pumps it to the body.

The pathway of blood through the heart includes the superior and inferior vena cava, right atrium, right ventricle, pulmonary arteries, lungs, pulmonary veins, left atrium, left ventricle, and aorta.

Coronary vessels are blood vessels that supply oxygen-rich blood to the heart muscle.

The left ventricle is more muscular than the right ventricle because it must pump blood with greater force to the entire body.

Atria are thin-walled chambers that receive blood from the veins. They pump blood into the ventricles.

Ventricles are thick-walled chambers responsible for pumping blood to the arteries. The right ventricle pumps blood to the lungs, and the left ventricle pumps blood to the body.

Atrioventricular (AV) valves are flaps of tissue located between the atria and ventricles. They prevent backflow of blood from the ventricles to the atria.

Semilunar valves are half-moon shaped valves located at the base of arteries leaving the heart. They prevent backflow of blood into the ventricles.

The superior vena cava carries deoxygenated blood from the head to the right atrium. The inferior vena cava carries deoxygenated blood from the lower body to the right atrium.

The pulmonary artery carries deoxygenated blood from the heart to the lungs. The pulmonary veins carry oxygenated blood from the lungs back to the left atrium.

The aorta is the largest artery in the body. It carries oxygenated blood from the left ventricle to the rest of the body.

Blood pressure is measured using a sphygmomanometer, commonly called a blood pressure cuff. It measures the pressure of blood in an artery as the heart contracts (systolic) and relaxes (diastolic).

Systolic pressure is the highest pressure in an artery, occurring when the ventricles contract and push blood out. Diastolic pressure is the lowest pressure in an artery, occurring when the ventricles relax and fill with blood.

Blood velocity is the speed at which blood flows through the vessels. It is fastest in arteries and slowest in capillaries.

The largest surface area of blood vessels is in the capillaries. This allows for efficient diffusion and exchange of nutrients and waste products between the blood and cells.

Factors like heart rate, contraction force, blood vessel diameter, and blood volume affect blood pressure.

A cardiac cycle is one complete heartbeat, involving contraction (systole) and relaxation (diastole) of the heart chambers.

Electrocardiograms (ECGs) record electrical impulses generated by the heart, allowing doctors to diagnose heart conditions.

The pulmonary circulation pathway involves the heart and lungs, carrying deoxygenated blood to the lungs for gas exchange and back to the heart with oxygenated blood.

The systemic circulation pathway involves the heart and the rest of the body, carrying oxygenated blood from the heart to the body cells and back to the heart with deoxygenated blood.