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What is the transport system in humans?

The circulatory system, the blood


What are the main 4 components of the blood?

Plasma, Platelets, Red Blood Cells, White Blood Cells


What is the plasma?
What is its function?

- A pale yellow liquid which carries nearly everything that needs transporting around your body.
- Some substances are carried by being dissolved directly (eg CO2)
- Function: Transporting carbon dioxide, digested food molecules, urea and hormones; distributing heat


What are some examples of substances carried by the plasma?

Red + White blood cells
Digested food products (glucose, amino acids)
Carbon dioxide (body cells to lungs)
Urea (liver to kidneys)
Heat energy


Why does blood plasma carry heat energy?

- Plasma helps to distribute heat throughout the body and to maintain homeostasis
- Including acid-base balance in the blood and body.
- It carries heat energy away from rapidly respiring cells (such as exercising muscles) and prevents them overheating
- It also provides heat energy to regions of the body where respiration takes place more slowly.


What are platelets?
More info

Small fragments of cells that help blood blot
No nucleus and suspended in the blood plasma


Steps of platelets/ blood clotting:

1) when blood vessel is damaged, platelets clump together to 'plug' the damaged area
2) This is called blood clotting


What do blood clots do?

They stop you losing too much blood and prevent microogansisms from entering the wound


How are platelets held together in a clot?

Platelets are held together by a mesh of a protein called fibrin (though this process also needs other proteins called clotting factors to work)


How do platelets stop bleeding (proteins)

- They release chemicals (an enzyme which digests fibrinogen, which is soluble, to fibrin, which is insoluble) that cause soluble proteins to form a mesh of insoluble fibres across the wound.
The fibrin mesh traps blood cells and causes a clot

- stick together to form clumps that get stuck in the mesh


What are red blood cells?

- Red blood cells transport the oxygen required for aerobic respiration in body cells.
- Carry oxygen from lungs to all the cells in the body.
- They must be able to absorb oxygen in the lungs, pass through narrow blood capillaries and release this oxygen to respiring cells.


What are the adaptations of red blood cells?

- Biconcave shape = larger surface area for absorbing and releasing oxygen
- They contain haemoglobin (which is what gives the blood it's colour - contains a lot of iron)
Haemoglobin can combine reversibly with oxygen = it means that it can combine with oxygen as blood passes through the lungs and release the oxygen when it reaches the cell
- No nucleus = frees up space for more haemoglobin, they can carry more oxygen
- Thin = only a short distance for the oxygen to diffuse to reach the centre of the cell
- Small and flexible = can fit through narrow blood capillaries


What does haemoglobin do?

Helps red blood cells absorb and release oxygen as oxygen needs to bind to something (the haemoglobin binds to the oxygen)


Haemoglobin in lungs =

haemoglobin and oxygen --> oxyhaemoglobin


Haemoglobin in body's tissues =

oxyhemoglobin breaks down to haemoglobin releasing the oxygen (then taken by cells)


What are white blood cells?

Important part of the immune system - ingest pathogens and produce antibodies


What are pathogens?

Microorganisms that cause disease


What is the job of the immune system?

To destroy the pathogens before they reproduce


What are the two types of white blood cells?

Phagocytes and Lymphocytes


What are phagocytes? Function?

Phagocytes detect things that are foreign to the body such as pathogens.
They then engulf and destroy them by digesting the pathogens using enzymes.
Phagocytes are non-specific, they attack anything that isn't meant to be there.


What are lymphocytes? Function?

Lymphocytes have a very large nucleus and produce chemicals (proteins) called antibodies
1) Every pathogen has unique molecules on it's surface called antigens
2) When lymphocytes come across a foreign antigen, they will start to produce antibodies
3) Antibodies stick onto foreign microorganisms in the blood, this either kills the microorganisms (as they break open and die) or causes them to clump together making it easier for phagocytes to engulf and destroy them.


lymphocytes, antibodies and memory cells

- The antibodies produced are specific to that type of antigen and won't lock onto any others
- The antibodies are then produced rapidly and flow around the body to mark all similar pathogens
- Memory cells are also produced, these remain in the body and remember a specific antigen.
- They can reproduce very fast if the same antigen enters the body again
- Therefore immune to most diseases you've already had. The body carries a 'memory' of what the antigen was like --> can produce loads of antibodies fast


What is an antigen?

A substance which can induce an immune response


What is an antibody?

Proteins that recognise and bind to antigens, which are unique molecules on the surface of pathogens (specific shape to match)
Specific proteins produced in response to exposure to a foreign agent.
Made by lymphocytes


What is vaccination about?

Vaccination is a way of preventing disease by making the body respond as if it had already been infected


What is the point of getting vaccinated?

When infected with a new pathogen, takes while for lymphocytes to produce the antibodies to deal with it. (In this time you can get very ill or even die)
To avoid this you can be vaccinated against some diseases


Explain the process of vaccination

Vaccination involves injecting dead or inactive pathogens into the body
Thee carry antigens, so even though harmless will still trigger an immune response.
Your lymphocytes produce antibodies to attack them
Memory cells are also produces so if live pathogens of the same type ever appear, the antibodies to kill them will be produces much faster and in greater numbers.


Define 'heart'

An organ that pumps blood through the circulatory system


What are the left chambers separated with from the right chambers?

A thick section of cardiac muscle called the 'septum'


How many chambers does the heart have?