Section 5- Blood and organs

CIRCULATORY SYSTEM:

Blood components:

Plasma- plasma components are substances carried in plasma eg. Vitamins, minerals, hormones

Platelets (P2)-help in blood clotting.

Red blood cells: to carry oxygen.

Structure and function of RBC:

Biconcave shape so a large surface area for diffusion of oxygen.

No nucleus so more space for haemoglobin to carry oxygen.

Anaemia is iron deficiency. Symptoms: shortness of breath and tiredness because there is less iron to make haemoglobin in red blood cells. Red blood cells carry oxygen to cells around the body for respiration to produce energy. If less red blood cells due to anaemia then less energy produced causing symptoms of tiredness.

High altitude impact on exercise:

At high altitudes there is lower oxygen levels. Athletes train there because they produce more red blood cells to carry oxygen. Therefore, when they return to normal altitudes they are more efficient at transporting oxygen in red blood cells to muscle cells needed for aerobic respiration.

White blood cells-to fight disease. There are two types: phagocytes and lymphocytes.

Phagocytes: engulf pathogens and are large.

Lymphocytes: produce antibodies that stick to antigens on pathogens to destroy them.

Vaccination (P2):

Vaccinations insert dead or inactive pathogens into the body, causing lymphocytes to produce antibodies to destroy them, producing memory cells to recognize pathogens. The body will produce more antibodies and faster. This is a secondary immune response.

Blood vessels:

	Arteries	Veins	Capillaries
Wall	Elastic fibres and thick walls	Elastic fibres and thin walls	Thin wall-only one cell thick
Lumen	Small lumen	Large lumen	Very small lumen
Pressure	High	Low	Low
Extra	Aorta has blood under highest pressure as going all over the body	Valves to prevent backflow of blood	Permeable wall
Diagram

Capillaries adaptations for exchange:

Permeable walls for diffusion.

Walls are one cell thick so a short diffusion distance.

The heart :

Summary of blood flow in heart (to understand not a question):

Right (deoxygenated): blood comes from the body in the vena cava, right atrium, past the tricuspid valve, right ventricle, semilunar valve, pulmonary artery to the lungs.

Left (oxygenated): blood comes from lungs in pulmonary vein, left atrium, bicuspid valve, left ventricle, semilunar valve, aorta to the body.

Structure of the circulatory system:

Coronary heart disease (CHD):

When coronaries arteries become blocked with plaque (fat) causing a lack of oxygen and then a heart attack. Risk factors include: diet high in saturated fat, high blood pressure, inactivity and smoking.

EXCRETION (URINARY SYSTEM):

Roles of the kidneys:

Removal of urea, adjustment of ion levels and water content.

Kidneys structure (P2):

If a person is dehydrated:

The pituitary gland releases ADH which makes the collecting ducts more permeable so more water is reabsorbed into the blood and there is less urine.