Biology Transport in Humans

Why can unicellular organisms rely on diffusion?

Why can unicellular organisms rely on diffusion?

Surface Area to Volume ratio is optimum for diffusion, and this rate of exchange is sufficient for unicellular organisms

Why do multicellular organisms need a transport system?

Multicellular organisms have a small surface area to volume ratio, so we need a transport system to be able to get all of the substances that cells need to the correct place

What is blood composed of?

Red blood cells, white blood cells, platelets and plasma

Role of plasma and waste products of respiration

The plasma transports the waste product of respiration to the lungs (CO2)

Role of plasma with heat energy?

The plasma transports heat energy created in respiration to other parts of the body to maintain core body temperature

Role of plasma with hormones

The plasma transports hormones from endocrine organs to the target tissues or organs

Role of plasma with urea

The plasma transports the waste product of the breakdown of proteins (urea) in the liver to the kidneys where it can be excreted

Role of plasma with digested food

The plasma transports dissolved particles absorbed from the small intestine to the requiring cells

How is the red blood cell adapted for transport of oxygen to do with the nucleus?

Red blood cells have no nucleus so there is more room for haemoglobin

How is the red blood cell adapted for the transport of oxygen to do with its structure?

The red blood cells has a biconcave disc shape to give them a large surface area to volume ratio to maximise diffusion of oxygen

How is the blood cells adapted for the transport of oxygen to do with haemoglobin?

Red blood cells are full of haemoglobin to carry the maximum amount of oxygen

What does the body do when a pathogen enters the blood stream?

When a pathogen enters the blood stream and multiplies, the body detects this and sends white blood cells to the pathogen

What do the lymphocytes do?

The lymphocytes recognizes its antigens and produce antibodies specific to the pathogen to mark it for the phagocytes to destroy

What do the phagocytes do?

The phagocytes change their shape to engulf the pathogen, and once the pathogen has been engulfed, the phagocytes produce enzymes to digest them

What can vaccinations consist of?

A vaccination can consist of a dead or weak pathogen which is injected into the patients blood stream.

What do the lymphocytes do when a vaccine is injected into the blood stream?

The lymphocytes develop antibodies specific for the pathogen, and some lymphocytes develop into memory cells

What is the role of the memory cells?

The memory cells stay in the blood stream for years, so if the pathogen enters the blood steam again, the memory cells will recognise the pathogen faster and produce larger quantities of the required antibody in a much shorter time, which is called the secondary immune response

What do platelets do when the skin is broken?

When the skin is broken, platelets release chemicals that cause the soluble fibrinogen proteins to convert into insoluble fibrin and form an insoluble mesh

What is the insoluble mesh purpose?

The insoluble mesh forms across the wound and trap red blood cells, forming a blood clot

What happens to the blood clot?

The blood clot eventually dries out and develops into a scab

Why is blood clotting important?

Blood clotting is important as it:

• prevents significant blood loss from wounds

• prevents the entry of any pathogens

• remains in place until new skin has grown underneath

Why is it significant that blood clots form to prevent blood loss?

Blood carries oxygen around the body so if there is not a sufficient amount of blood in the body, oxygen can not get to cells and respiration does not occur meaning we don’t get energy

What is the structure of the heart?

The heart is composed of several layers of tissue and is divided into four chambers: the right atrium, right ventricle, left atrium, and left ventricle

When blood is pumped around the body, what happens to the deoxygenated blood?

The deoxygenated blood coming from the body flows through the vena cava into the right atrium

What does the right atrium do with the deoxygenated blood?

The right atrium contracts and the blood is forced through the tricusipid valve into the right ventricle

What does the right ventricle do with the blood?

The right ventricle contracts and blood is pushed through the semilunar valve into the pulmonary artery

Where does the blood go in the pulmonary artery?

The blood travels to the lungs at a low pressure and gas exchange takes place

What happens at the same time?

At the same time, oxygenated blood returns via the pulmonary vein to the left atrium

What happens to the oxygenated blood in the left atrium?

The left atrium contracts, and forces blood through the bicuspid valve into the left ventricle

What happens to the blood in the left ventricle?

The left ventricle contracts and the blood is forced through the semilunar valve and out through the aorta

Why does the left ventricle have thick muscle walls?

The left ventricle has thick muscle walls to produce a high enough pressure for blood to travel around the whole body

Why does heart rate change during exercise?

During exercise, the cells of the muscles respire more rapidly in order to provide more energy for muscle contraction. An increase in respiration means an increase in requirement of oxygen and glucose. Therefore, the heart rate increases to deliver more oxygen and glucose and remove waste more frequently

What happens to our heart rate when adrenaline is released into the body?

Our heart rate increases when the adrenal glands release adrenaline. This is to increase our cardiac output so muscles can respond more efficiently to threats

What happens to the lining of the coronary artery in the stages of coronary heart disease?

The lining of the coronary arteries gets damaged and becomes rough

What does this cause?

This causes cholesterol deposits from blood to build up in the wall of the artery, and overtime fibrous tissues builds up around the cholesterol forming a plaque

What is the consequence of this build up?

In consequence, it is more difficult for blood to flow through the artery which increases blood pressure causing more chance of further damage and more plaques form

What happens to the blood reaching the heart?

Less oxygen rich blood reaches the heart muscles through the coronary artery and so the heart muscles respire anaerobically, which causes lactic acid to be produced

What happens if a total blockage occurs?

A total blockage of the arteries will cause heart muscles cells to die, and therefore a heart attack

How does obesity increase the risk of a heart attack?

Obesity means carrying extra weight which can strain the heart

How does smoking increase the risk of a heart attack?

Smoking causes chemicals in smoke to damage the lining of the coronary arteries and plaques form

How does high blood pressure increase the risk of a heart attack?

High blood pressure increases the force of blood against the artery walls and leads to damage of the vessels and plaques form

How does high cholesterol increase the risk of a heart attack

High cholesterol speeds up the build of plaques in arteries leading to blockages

Structure and explanation of the arteries?

• Thick muscle walls to transport high pressure blood away from the heart

• Narrow lumen to maintain blood pressure

• Elastic fibres to stretch under pressure to even flow

Structure and explanation of the veins?

• Thin muscle walls to carry low pressure blood

• Valves to stop blood from flowing backwards

• Wide to allow low pressure blood to flow

Structure and explanation of the capillaries?

• High surface area and one cell thick diffusion distance to maximise gas exchange by diffusion

• Extremely narrow to allow one red blood cells at a time which slows down blood flow for more efficient gas exchange