CIE IGCSE Biology Unit 9: Transport in Humans

circulatory system

system of blood vessels with a pump and valves to ensure one-way flow of blood

Single circulatory system

Blood only passes once through the heart

Double circulatory system

Blood completes two cycles around the heart before leaving to the rest of the body

Advantages of double circulation

Deliver greater blood flow rate to tissues around body

Heart structure

Divided into 4 sections:

Right atrium

Left atrium

Right ventricle

Left ventricle

Importance of the septum

separating oxygenated and deoxygenated blood

Cardiac cycle

Consists of 3 stages:

Cardiac diastole: when chambers of heart are relaxed and filled with blood

Atrial systole: when atria contract leading to ventricular filling with blood

Ventricular systole: Contraction of ventricles to allow blood to leave heart

Electrocardiogram (ECG)

Used to test person's heart rhythm and electrical activity of the heart

Effect of exercise on heart rate

Exercise increases heart rate as the heart needs to supply more oxygen to the muscles to undergo respiration for production of energy

Effect of exercise on pulse rate

Arteries

Used to transport blood from heart

Veins

Used to transport blood from body to heart

Capillaries

One cell thick, used for diffusion of nutrients from blood to cells

Structure of Artery, Vein, and capillaries

Arteries: small lumen, thick muscular wall to handle pressure of blood from heart

Veins: have large lumen to transport blood back to heart, have valves to prevent backflow of blood

Capillaries: One cell thick to allow diffusion of substances

Arterioles

Arteries branch into smaller arterioles

Venules

Venules allow deoxygenated blood to return to the veins to be transported back to the heart

Shunt vessels

Artery is linked directly to vein, controls blood flow by constriction or dilation, bypasses capillaries

Coronary Heart Disease

The build up of plaque in arteries that block blood flow to rest of body

Risk Factors of Coronary Heart Disease

High cholesterol, high blood pressure, family inherited trait ,and diet are all factors that cause CHD

Treatment of Coronary Heart Disease

Coronary artery bypass: Blocked artery is bypassed by another artery taken from the patient

Coronary angioplasty: Small balloon is inflated inside the blocked artery and a stent is added to keep the artery open

Antiplatelet medicines: Aspirin, prevents blood clots from forming in arteries, risk of huge blood loss when there is cut as blood does not clot due to medication

Components of blood

red blood cells, white blood cells, platelets and plasma

White Blood Cells

Contains lymphocytes and phagocytes used for phagocytosis and antibody production

Platelets

Used for clotting

Clotting

the conversion of fibrinogen to fibrin to form a mesh to prevent blood loss and the entry of pathogen

Plasma

Used for transport of blood cells, ions,

soluble nutrients, hormones and carbon

dioxide

Lymphocyte

Used to produce antibodies to protect against pathogens in the body

Phagocyte

used for phagocytosis

Phagocytosis

-Antibodies released to agglutinate pathogens

-Phagocytes engulf pathogens

-Enzymes released inside phagocytes that kill pathogen and make it a food source for the phagocyte

Lymphatic System

Network of tissues and organs that rid the body of toxins, waste and unwanted substances

Lymphatic vessels

Transport lymph(tissue fluid) to subclavian veins, have valves to prevent backflow, slow and rely on peristalsis to move

Lymph nodes

Contain lymphocytes that make antibodies

Exchange of materials between capillaries and tissue fluid

-Proteins are transported in lymph vessel

-Bacteria may be picked up and destroyed in lymph nodes by lymphocytes