Biology IGCSE unit 4 human transport

components of blood

• red blood cells

• white blood cells

• plasma

• platelets

what is transported in plasma?

carbon dioxide, urea, glucose, amino acids, hormones

how are red blood cells adapted to transport oxygen?

• large surface to volume ratio so more oxygen can be carried

• no nucleus so more room for oxygen

• haemoglobin binds to oxygen

how pathogens are prevented

• skin is a barrier

• tears, eye lashes, nose hair traps

2 types of white blood cells?

phagocytes, lymphocytes

phagocytes

engulf pathogens and secrete digestive enzymes

lymphocytes

recognises antigens on pathogens and secretes antibodies to destroy that pathogen. can neutralise toxins of pathogens and make pathogens stick together

the movement of the blood around the body starting at right atrium

• deoxygenated blood enters right atrium via vena cava

• right atrium contracts, force blood into right ventricle

• leaves right ventricle via pulmonary artery

• blood flows to the lungs

• blood becomes oxygenated

• blood returns to heart and enter left atrium via pulmonary vein

• left atrium contracts, force blood into left ventricle

• leaves left ventricle, forced to aorta

• oxygenated blood flows around and is used in respiration

why are walls of ventricles thick?

because they pump blood further and at a higher pressure

why is wall of left ventricle thicker?

pump blood further and at higher pressure

why are coronary arteries essential?

supplies heart with its own oxygen, if they get blocked it will cause a heart attack

what factors increase chance of coronary heart disease?

• high fat diet

• smoking

• stress

• heriditary

why reducing blood supply to heart muscles can cause heart attack?

• less oxygen

• less aerobic respiration

• lactic acid

• low pH

how is our heart rate increased?

• adrenaline

• exercise leads to more carbon dioxide by muscles

• receptors detect more carbon dioxide so accelerator nerve raises heart rate

arteries

• narrow lumen, blood is at high pressure

• thick wall, to withstand high pressure blood

veins

• thick lumen, blood is at low pressure

• thin wall

• valves to prevent backflow of blood

capillaries

• narrow lumen

• thin walls, 1 cell thick for short diffusion distance