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Angioplasty

The use of a catheter to insert a small deflated balloon into a blocked or narrowed artery. Once in place, the balloon is inflated, widening the artery.

Aorta

The artery that takes oxygenated blood away from the heart to the body.

Arteriole

A type of blood vessel that connects the arteries and capillaries.

Artery

A type of blood vessel that carries blood away from the heart to the tissues, under high pressure.

Aspirin

A drug used to treat coronary heart disease by preventing the formation of blood clots in the arteries.

Atria

The two upper chambers of the heart that receive blood from the veins and pump blood into the ventricles.

Atrioventricular (AV) valves

The valves found between the atria and ventricles that prevent the backflow of blood from the ventricles.

Bicuspid valves

The atrioventricular valves found between the left atrium and left ventricle.

Blood

A tissue containing red blood cells, white blood cells, platelets and plasma.

Blood clotting

A defence mechanism that prevents excessive blood loss and the entry of microorganisms.

By-pass surgery

A surgical procedure that uses a blood vessel to divert blood around a blockage in the coronary artery.

Capillaries

Thin blood vessels that connect the arteries and veins and are the site of exchange of substances.

Circulatory system

The transport system in mammals consisting of a pump, blood vessels and valves.

Coronary arteries

The arteries that supply the heart muscle with food and oxygen.

Coronary heart disease

A disease caused by the build-up of fatty deposits inside the coronary arteries.

Double circulatory system

A circulatory system in mammals where blood flows through the heart twice in two circuits.

Electrocardiogram (ECG)

A technique used to measure the spread of electrical activity through the heart.

Heart sounds

The sounds of the heart valves opening and closing, represented as ‘lub-dup’.

Lactic acid

The product of anaerobic respiration in animal cells, leading to cramp and fatigue.

Lymph

Modified tissue fluid that drains into the lymphatic system.

Lymphatic system

A collection of organs and tissues that drain lymph and are involved in immunity.

Lymphatic vessels

Thin-walled vessels that carry lymph through the lymphatic system.

Lymph nodes

Swellings in the lymphatic vessels that store and release lymphocytes.

Lymphocyte

A type of white blood cell that produces antibodies specific to particular antigens.

Phagocyte

A type of white blood cell that engulfs pathogens and digests them.

Plasma

The main component of blood that carries red blood cells and contains nutrients and hormones.

Platelets

Small fragments of cells involved in blood clotting.

Pulmonary arteries

Arteries that carry deoxygenated blood away from the heart to the lungs.

Pulmonary veins

Veins that carry oxygenated blood from the lungs to the heart.

Pulse rate

The number of pulses felt in an artery per minute.

Red blood cell

A type of blood cell that contains haemoglobin and transports oxygen.

Renal arteries

Blood vessels that carry oxygenated blood to the kidneys.

Renal veins

Blood vessels that drain the kidneys.

Semilunar valves

Valves found between the ventricles and arteries that prevent backflow.

Septum

The wall of muscle separating the left and right sides of the heart.

Shunt vessels

Blood vessels that link arterioles to venules, allowing blood to bypass capillaries.

Single circulatory system

A circulatory system where blood travels one circuit, as found in fish.

Stent

A small tube surgically implanted to keep arteries open.

Tissue fluid

Fluid surrounding cells with the same composition as plasma but without red blood cells.

Tricuspid valves

The atrioventricular valves found between the right atrium and right ventricle.

Valves

Structures in the heart that prevent the backflow of blood.

Vein

A blood vessel that carries blood toward the heart under low pressure.

Vena cava

The vein that returns deoxygenated blood to the heart from the body.

Ventricles

The two lower chambers of the heart that expel blood into the arteries.

Venule

A blood vessel that connects capillaries and veins.

White blood cells

Cells of the immune system that protect the body from pathogens.

Alveoli

Tiny, thin-walled air sacs in the lungs for gaseous exchange.

Breathing rate

The number of breaths taken per minute.

Bronchi

Divisions of the trachea leading into the lungs.

Bronchioles

Many small divisions of the bronchi.

Cilia

Hair-like structures that waft substances across tissue surfaces.

Ciliated cell

Epithelial cells lined with cilia in the respiratory tract.

Diaphragm

A muscle that separates the thorax and abdomen and aids in breathing.

Expiration

The process of breathing out, where thoracic pressure rises.

Expired air

Air that is breathed out, having a higher concentration of carbon dioxide.

External intercostal muscles

Muscles found between the ribs involved in exhalation.

Gaseous exchange

The exchange of respiratory gases between an organism and its environment.

Goblet cells

Cells that secrete mucus in the respiratory tract.

Inspiration

The process of breathing in, where thoracic pressure falls.

Inspired air

Air that is breathed in, having a higher concentration of oxygen.

Intercostal muscles

Muscles situated between the ribs that control rib movement.

Internal intercostal muscles

Muscles involved in inhalation and exhalation.

Larynx

A structure at the top of the trachea involved in breathing and sound production.

Limewater

A chemical used to test for carbon dioxide presence.

Lungs

Air-filled organs containing alveoli for gas exchange.

Mucus

A slimy substance secreted by goblet cells to trap pathogens.

Ribs

Bones that protect the chest cavity.

Trachea

The primary airway carrying air from the nasal cavity to the chest.

Ventilation

The movement of fresh air into and stale air out of the lungs.