Circulatory system

3. Human Biology

Circulatory System

Group of organs that permits blood to circulate and transport important substances to body cells and removes wastes

Heart

Muscular organ in most animals, pumps blood through the blood vessels of the circulatory system.

Left atrium

The left upper chamber of the heart

Right atrium

The right upper chamber of the heart

Left ventricle

The left lower chamber of the heart

right ventricle

the right lower chamber of the heart

valves

One-way doors in the heart, ensuring blood flow moves in one direction.

blood vessels

tubular structures carrying blood through tissues and organs: veins, arteries or capillaries

veins

vessels that carry blood to the heart

arteries

vessels that carry blood away from the heart

capillaries

narrowest blood vessels. they join the arteries and the veins, and allow blood to reach cells.

coronary arteries

Arteries that are on the surface of the heart and send smaller branches into the heart muscle. They supply the heart muscle with blood carrying oxygen and nutrients.

circulation

Movement of blood through the body in a figure-8 motion

pulmonary circulation

Type of circulation that takes deoxygenated blood from the right ventricle to the lungs and returns oxygenated blood to the left atrium.

systemic circulation

Type of circulation that takes oxygenated blood from the left ventricle to all tissues of the body and returns deoxygenated blood to the right atrium.

Cardiac cycle

the sequence of events that occurs when the heart beats. lasts around 0.8 seconds

sinoatrial (SA) node

A specialised bundle of neurons (nerve cells) that controls heart rates. In the upper part of the right atrium.

diastole

filling of the heart

systole

pumping blood out of the heart

ventricular and atrial diastole

(Cardiac Cycle) Atrioventricular valves are open + semilunar valves are closed. Deoxygenated blood flows into the vena cava. Oxygenated blood flows into the left atrium from the pulmonary vein.

atrial systole

(Cardiac Cycle) Both atria contract. Blood is forced into the left and right ventricles through the open atrioventricular valves.

ventricular systole

(Cardiac Cycle) atria relax and ventricles contract. blood is forced into the aorta and pulmonary artery.

ventricular diastole

one cardiac cycle completed. semilunar valves shut, atrioventricular valves open.

cardiac output

volume of blood pumped by the heart per minutes. Output is CO (ml/min) = stroke volume (ml/beat) X HR (beats/min)

venules

small veins

arterioles

small arteries

tissue

a large mass of similar cells that make up a part of an organism and perform a specific function

epithelial tissue

covering or lining tissue e.g. skin, heart, digestive tract

connective tissue

joining and support tissue e.g. blood adipose tissue, ligaments & tendons, cartilage

muscular tissue

tissue that can contract and relax to bring about movement.

nervous tissue

tissue that transmits nerve impulses.

lymphatic system

a one-way drainage system of delicate tubes throughout the body. (from body tissues to heart only). returns excess tissue fluid to the blood circulation

lymph

the fluid carried by the lymphatic system. a clear yellow liquid that carries white blood cells.

interstitial fluid

the fluid that bathes cells. it comes from substances that leak out of blood capillaries.

lymph vessels

thin walled vein-like tubes that carry lymph. these contains valves to prevent backflow of lymph

lymph nodes

small bean-shaped, mesh-like structures that filter lymph fluid and microorganisms. contain high concentrations of white blood cells.

white blood cells

cells that protect our bodies from sicknesses. they patrol through our bloodstream in search of harmful pathogens.