Life Processes - Circulation

Vocabulary flashcards covering the components of blood, the structure and function of the heart, blood vessels, and the types of circulation in the human body.

Blood

A red coloured fluid connective tissue that circulates in the Human Body, supplying nutrients and oxygen while collecting waste products and carbon dioxide.

Hemoglobin

A protein made up of four globular protein subunits, each containing a heme group, responsible for the red colour of blood and for binding to oxygen and carbon dioxide.

Red Blood Cells (Erythrocytes)

Biconcave-shaped cells filled with hemoglobin that transport oxygen from the lungs to body tissues and carry carbon dioxide back to the lungs.

White Blood Cells (Leukocytes)

Part of the body’s immune system, these cells help fight against infections and diseases by identifying and attacking foreign pathogens.

Platelets (Thrombocytes)

Small, colourless cell fragments formed in the bone marrow from megakaryocytes that play a critical role in blood clotting (hemostasis).

Plasma

The straw-coloured fluid of the blood, making up about $55\%$ of blood volume, composed of water with dissolved proteins, salts, glucose, and nitrogenous compounds.

Biconcave Shape

The characteristic shape of Red Blood Cells that increases their surface area-to-volume ratio and makes them flexible enough to squeeze through narrow capillaries.

Erythropoietin

A hormone produced by the kidneys in response to low oxygen levels that regulates the production of Red Blood Cells in the bone marrow.

Anaemia

A condition resulting from a lack of sufficient Red Blood Cells or haemoglobin in the blood, leading to fatigue, weakness, and shortness of breath.

Sickle Cell Disease

A genetic disorder that affects the shape of Red Blood Cells and can cause pain, organ damage, and stroke.

Thalassemia

An inherited blood disorder that affects the production of haemoglobin, leading to anaemia and other complications.

Neutrophils

The most abundant type of White Blood Cell, primarily responsible for fighting bacterial infections.

Lymphocytes

A type of White Blood Cell involved in fighting viral infections and producing antibodies to neutralise foreign substances.

Monocytes

White Blood Cells responsible for fighting infections and participating in tissue repair.

Eosinophils

White Blood Cells involved in the immune response against parasitic infections and allergic reactions.

Basophils

White Blood Cells involved in the immune response against allergic reactions and inflammation.

Hemostasis

The process of blood clotting which involves platelet activation, clot formation, and clot dissolution.

Arteries

Thick-walled, muscular, and elastic blood vessels that carry oxygenated blood away from the Heart; the aorta is the largest example.

Veins

Thin-walled blood vessels that carry deoxygenated blood back to the Heart and contain valves to prevent the backflow of blood.

Capillaries

Tiny blood vessels with very thin walls that connect arteries and veins, facilitating the exchange of oxygen, nutrients, and waste products.

Circulatory System

The transport system in human beings responsible for the movement of oxygen, nutrients, hormones, and waste products throughout the body.

Lymphatic System

A network of vessels, organs (like the spleen and thymus), and tissues that helps maintain fluid balance and defends against infections.

Lymph

A yellowish, clear fluid formed from blood capillaries that contains White Blood Cells and proteins but lacks Red Blood Cells.

Pericardium

A sheath of tissue that protects the heart and contains a fluid to reduce friction during heartbeats.

Septum

A muscular wall that separates the right and left sides of the heart to prevent the mixing of oxygenated and deoxygenated blood.

Right Atrium

The heart chamber that receives deoxygenated blood from the body and pumps it into the right ventricle.

Left Atrium

The heart chamber that receives oxygenated blood from the lungs via the pulmonary vein.

Right Ventricle

The lower heart chamber that pumps deoxygenated blood to the lungs for oxygenation.

Left Ventricle

The heart chamber with the thickest wall, responsible for pumping oxygenated blood to the entire body.

Sinoatrial (SA) Node

Located in the right atrium, it is the Heart’s natural pacemaker that originates electrical signals to control the cardiac cycle.

Atrioventricular (AV) Node

Located between the atria and ventricles, it relays electrical signals from the SA node to the Bundle of His.

Purkinje Fibres

Specialised cells that conduct electrical impulses throughout the ventricles, causing them to contract during systole.

Diastole

The phase of the cardiac cycle during which the heart relaxes and fills with blood from the atria.

Systole

The phase of the cardiac cycle during which the ventricles contract, pushing blood out of the heart and into the arteries.

Double Circulation

A circulation type where blood passes through the heart twice in one cardiac cycle, consisting of pulmonary and systemic circulation.

Cardiac Cycle

One complete heartbeat consisting of the contraction and relaxation of all four chambers; occurs roughly $72$ times per minute in a normal adult.

Blood Pressure

The force of blood against the arteries, normally maintained between $90-120/60-80\,mmHg$.

Sphygmomanometer

An instrument used for measuring blood pressure in millimetres of mercury ($mmHg$).

Systolic Pressure

The first or upper number in a blood pressure reading (e.g., $120$), representing the pressure during ventricular contraction.

Diastolic Pressure

The second or lower number in a blood pressure reading (e.g., $80$), representing the pressure when the heart is at rest.