Transport in Humans

What is in blood

In blood there a four components there are plasma, red blood cells, white blood cells and platelets.

What is plasma

Plasma is the liquid part of the blood that carries dissolved substances around the body such as digested food products, carbon dioxide, urea, hormones, heat and energy.

Adaptations of red blood cells

They have a biconcave shape to give a large surface area for the absorption of oxygen

They contain a high concentration of haemoglobin which binds with oxygen so it can be taken to the lungs

They don’t have a nucleus which means they have more space for haemoglobin to carry oxygen

What cells are part of the immune system and how.

The White blood cells (leucocytes) support the immune system.

Phagocytes ingest pathogens. They detect foreign bodies and engulf them, they digest them using enzymes. They are non-specific and will attack anything that is not meant to be there

Lymphocytes produce antibodies that lock onto foreign antigens on the pathogens, The antibodies lock onto the pathogens marking them out for destruction. The antibodies lock onto the specific antigen allowing the antibodies lock onto them faster. This creates memory cells, allowing the antibodies to be produced quicker if the same pathogen invades again.

What do the valves do

Mitral valves:

• Bicuspid-left side,

• Tricuspid- right side

• Prevents backflow of blood from ventricles into atria

Semi-lunar valves:

• At aorta and pulmonary artery openings

• prevents backflow into ventricles

What is the function of the heart

The function is to pump blood around the body and to the lungs

The changes of heart rate during exercise

Cardiac Output= Stroke volume x Heart rate

Short term: Increase heart rate, rapid heartbeat and elevated blood pressure

Long term: Stronger heart muscle, lower resting heart rate.

What is coronary heart disease and its factors that cause it

It is when the coronary artery gets blocked and the cells in the heart run short of oxygen; if this happens they won’t be able to contract.

Factors: smoking, obesity, excessive alcohol consumption and lack of exercise

The structure and roles of arteries

To take blood away from the heart. It has thick walls of muscle and elastic fibre to stretch and recoil to maintain high blood pressure of blood flowing through them.

The structure and roles of veins

Carry blood towards the heart. It has thin walls and larger lumen because it carries blood at a lower pressure and has valves to prevent the backflow of blood.

The structure and role of capillaries

It allows exchange of gases. Their walls are one cell thick- which means it has a short diffusion distance.

The structure of circulation.

Double circulation - blood passes through the heart twice in every full circuit of the body.

Pulmonary-lungs

Coronary-Heart

Renal-kidneys

Hepatic portal- liver