IGCSE Biology 9.1 Circulatory System - Revision Flashcards

A comprehensive set of Q&A flashcards covering circulatory system concepts from the lecture notes, including heart anatomy, blood vessels, blood components, and related physiology.

What are the main components of the circulatory system?

A pump (the heart), a network of blood vessels (arteries, veins, capillaries), and valves to ensure one-way blood flow.

How many chambers and what type of circulation do fish have?

Two-chambered heart with a single circulation; blood passes through the heart once per body circuit.

How many chambers and what type of circulation do mammals have?

Four-chambered heart with double circulation; blood passes through the heart twice per body circuit.

Which side of the mammalian heart receives deoxygenated blood from the body?

The right side (right atrium) receives deoxygenated blood from the body.

Which side pumps oxygenated blood to the body?

The left side pumps oxygenated blood to the body.

What is the septum in the heart?

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

Where are the coronary arteries and what is their role?

They supply blood to the heart muscle (the myocardium) itself.

What is the complete flow path of blood through the mammalian heart?

Right atrium → tricuspid valve → right ventricle → pulmonary artery → lungs → pulmonary vein → left atrium → bicuspid valve → left ventricle → aorta.

What are the atrioventricular valves and their names?

Valves between atria and ventricles: tricuspid (right) and bicuspid/mitral (left); they open when the atria contract and close when the ventricles contract to prevent backflow.

What are the semilunar valves and where are they located?

Valves at the exits of the heart in the pulmonary artery and aorta; they open when ventricles contract and close to prevent backflow.

What monitors heart activity besides an ECG?

Pulse rate (beats per minute) and listening to valve sounds with a stethoscope.

What is the unit for measuring heart rate or pulse rate?

Beats per minute (bpm).

What is typically measured to investigate the effects of exercise on heart rate?

Pulse rate at rest and after exercise, recorded at intervals until it returns to resting rate.

What causes coronary heart disease (CHD)?

Blockage of coronary arteries by plaques/fatty deposits (cholesterol) reducing elasticity and blood flow.

What is angina?

Chest pain caused by partial blockage of coronary arteries reducing blood flow to the heart muscle.

What is a heart attack?

Complete blockage of a coronary artery, preventing blood flow and respiration to heart cells, possibly causing death.

Which vessels supply blood to and from the liver?

Hepatic artery brings oxygenated blood to the liver; hepatic portal vein carries deoxygenated blood from the gut to the liver; hepatic vein returns blood from the liver to the heart.

What are the main components of blood?

Red blood cells, white blood cells, platelets, and plasma.

What is the structure and function of red blood cells?

Biconcave discs with no nucleus and containing hemoglobin; transport oxygen.

What are the two main types of white blood cells and their functions?

Phagocytes (engulf pathogens) and lymphocytes (produce antibodies and antitoxins).

What is the role of platelets in blood clotting?

Platelets release chemicals that convert soluble fibrinogen to insoluble fibrin, forming a clot that seals wounds.

What is plasma and what does it transport?

A straw-coloured liquid that transports carbon dioxide, nutrients, urea, ions, hormones, and heat energy.

How do arteries differ from veins in structure and function?

Arteries carry blood away from the heart at high pressure with thick muscular walls and narrow lumens; veins carry blood to the heart at low pressure with thin walls, large lumens, and valves.

What are capillaries and how are they adapted for exchange?

Capillaries have walls one cell thick and leaky walls to allow diffusion of substances between blood and tissues.

Describe the path of blood through the body’s vessels from heart to organs and back.

Arteries → arterioles → capillaries → venules → veins; veins return blood to the heart.

What are arterioles and venules?

Narrow vessels that connect arteries to capillaries (arterioles) and capillaries to veins (venules).

Which vessels carry blood to and from the liver and what are their roles?

Hepatic artery (to liver, oxygenated), hepatic portal vein (from gut to liver, deoxygenated), hepatic vein (from liver to heart).

What is unique about the liver’s blood flow in circulation?

Blood from the gut goes to the liver via the hepatic portal vein for processing before reaching the heart.

How are arteries, veins, and capillaries structurally adapted to their functions?

Arteries: thick walls with elastic fibres to withstand high pressure; Veins: large lumen, valves to prevent backflow; Capillaries: thin walls for diffusion and exchange.

How is blood flow to the lungs different from the rest of the body in terms of pressure?

Blood flowing to the lungs is at lower pressure to prevent capillary damage in the delicate lung tissue.

What is the role of the heart’s septum in circulation?

It prevents mixing of oxygenated and deoxygenated blood between the two heart sides.