Circulatory system, Blood & Immune system

What are the components of the blood?

What are the components of the blood?

Red blood cells

white blood cells

plasma - acts as a suspension to carry cells around body

platelets

Substances transported in plasma

Carbon dioxide, urea, glucose, amino acids, hormones

How are red blood cells adapted for their function?

Biconcave disc shape - maximises surface area to volume ratio - transports as much oxygen as possible

No nucleus - more room for oxygen

Contains haemoglobin (pigment) - binds to oxygen forming oxyhaemoglobin

How pathogen entry is prevented

Skin acts as a barrier

Hydrochloric acid in stomach destroys pathogens

Tears, eyelashes, nose hair - prevents pathogens from entering eyes and nose

Name the two types of white blood cell

phagocytes and lymphocytes

What is the function of a phagocyte?

Engulf/ingest pathogens by enclosing them inside a vacuole and secrete digestive enzymes to destroy them

Function of a lymphocyte?

Recognise antigen on pathogen and secretes antibodies to destroy that specific pathogen

Labels pathogen to help phagocyte recognise it

Neutralises toxins produced by pathogen

Causes bacterial cell to burst open

Causes pathogens to stick together

Why do humans need a circulatory system?

Diffusion is too slow bc surface area to volume ratio is too small

What are the 4 chambers of the heart?

Label a diagram of the heart

Top left - right atrium

Top right - left atrium

Bottom left - right ventricle

Bottom right - left ventricle

pulmonary, hepatic, renal and coronary meaning

pulmonary - relating to the lungs

hepatic - relating to liver

renal - relating to kidneys

coronary - relating to the heart

Steps of circulatory system

Label a diagram

Oxygen in lungs is delivered to heart to the left atrium via pulmonary vein

Left atrium contracts, bicuspid valves open, forcing blood into left ventricle

Left ventricle contracts forcing blood into aorta

Blood goes around body and delivers oxygen around body, oxygen is removed and used by respiring cells

Now deoxygenated blood returns to the heart via vena cava into right atrium

Right atrium contracts forcing blood through tricuspid valves into right ventricle

Right ventricle contracts forcing blood into the lungs via pulmonary artery to be oxygenated

Characteristics of the heart

Walls of ventricles are thicker than atria walls bc they pump blood at a higher pressure

Wall of left ventricle is thicker than wall of the right ventricle because it pumps blood at a higher pressure

Why is it called the double circulatory system?

Bc blood passes through the heart twice for every one time it passes around the body

What is the hepatic portal vein?

Takes blood from digestive system to liver

What is the function of the coronary arteries?

Supply heart with its own oxygen requirements as it can’t obtain its oxygen needs from blood flowing through it

What does it mean when someone gets a heart attack?

Fatty deposits get offloaded in the walls of the coronary arteries. The coronary arteries get blocked, oxygen can’t reach the respiring cells in the heart muscle. The cells start to respire anaerobically, produces lactic acid which poisons the muscle cells, so part of it dies

Factors that increase chance of coronary heart disease

high fat diet

smoking

stress

sedentary lifestyle (lack of exercise)

hereditary

diabetes

How can reducing blood supply increase chance of a heart attack?

Less oxygen

Less aerobic respiration

More anaerobic respiration

Lactic acid produced

Low pH

Why a heart rate increases during exercise?

Cells are respiring more for energy so more carbon dioxide is produced

CO2 flows in the blood and detected by aorta and carotid artery

This sends impulses to brain, specifically to the medulla part and the accelerator nerve

The accelerator nerve causes an increase in heart rate, so more oxygen can be delivered to muscles and more CO2 can be removed

Arteries vs veins vs capillaries

Arteries carry blood away from your heart. Veins carry blood back toward your heart. Capillaries, the smallest blood vessels, connect arteries and veins

Structure of artery

Narrow lumen (hole - like in a straw) - blood forced through at a high pressure

Artery walls are very thick to withstand pressure, made of muscle and elastic fibre

Structure of vein

Wide lumen - blood travels at a much lower pressure

Walls of vein are thin made of muscle and elastic fibre

They contain valves which prevent backflow of blood

Structure of capillaries

Supply all our cells with oxygen

One cell thick walls - short diffusion distance

Extremely narrow lumen