Transport in humans

Question 1

Why can unicellular organisms rely on diffusion for movement of substance into and out of cells?

Answer 1

As they only have one cell they have a big surface area to volume ratio so diffusion is more efficient. The substances have to travel though one thin wall. It needs substance such as glucose and oxygen through diffusion.

Question 2

Why do multicellular organisms need a transport system?

Answer 2

They have a much lower surface area to volume ratio as they are bigger so they cannot rely on diffusion alone to get necessary substances such as oxygen and glucose. . They need a transport system

Question 3

Composition of blood

Answer 3

Red blood cells, white blood cells, platelets and plasma

Question 4

What is the role of plasma

Answer 4

It transports different types of substances such as carbon dioxide, digested food, urea, hormones and heat energy

Question 5

What is the role of Red blood cells and how are they adapted to their function.

Answer 5

They transport oxygen
They have a biconcave shape which increase surface area allowing higher diffusion,
they do not have a nucleus which means less space is used
it also contains haemoglobin which transports oxygen and carbon dioxide.
When haemoglobin reacts with oxygen it creates
Oxyhaemoglobin

Question 6

What is the first line of defence

Answer 6

Prevents entry to bloodstream
Skin (barrier)
Tears
Mucus
Stomach acid

Question 7

What are platelets?

Answer 7

They are small cell fragments that travel around the bloodstream.
When you have been cut they travel to the location of injury, they create a barrier called blood cut to stop the bleeding.
Other factors come into play, specifically fibrinogen helps out. It now turns into Fibrin which creates fibres in a sort of web so now less blood can escape.

Question 8

What are Phagocytes?

Answer 8

They are 1 type of white blood cells.
They ingest and absorb pathogen and destroy them
Or they release an enzyme to destroy them
Once absorbed they can send a message to nearby Lymphocytes to tell then the antibody needed to neutralise them

Question 9

What are Lymphocytes?

Answer 9

Every Lymphocyte carries a specific antibody which fits on to specific antigen. When a lymphocyte meets the appropriate antigen it creates many copies of antibodies.
they bind to them and damage or destroy them
they coat pathogens, clumping them together so that they are ingested easily by phagocytes
they bind to the pathogens and release chemical signals to attract more phagocytes

Question 10

What are pathogens?

Answer 10

A bacteria, virus or other organism which can cause disease.
They also produce antigens

Question 11

What is a vaccination?

Answer 11

A preparation of Antigenic material as dead or harmless pathogens given by injection or orally.
These act as antigens, when put in the body they stimulate white blood cell to produce antibodies, the memory cell then will recognise the next time the pathogen attacks the Lymphocytes will be ready and take care of it very quickly. You are now immune to that disease.

Question 12

When you get your Vaccination what do white blood cells do?

Answer 12

Plasma cells start to produce antibodies specific to antigen
Memory cells are produced
More antibodies produced

Question 13

What is the function of the heart?

Answer 13

To pump blood around the body

Question 14

Describe the structure of the heart?

Answer 14

It has two atria (1 atrium) to collect the blood
It has two ventricles to pump blood around the body
Valves, to prevent blood from flowing backwards
sinoatrial node, atrio ventricular node

Question 15

How do the left and right side of the heart differ by what they do?

Answer 15

The right side of the heart pumps de-oxygenated blood to the lungs via the pulmonary artery. The right side pumps oxygenated blood to the rest of the body via the aorta

Question 16

Structure and function of Arteries

Answer 16

carry blood away from the heart (always oxygenated apart from the pulmonary artery which goes to the lungs)
Have thick muscular walls
Have small passageways for blood (internal lumen)
Contain blood under high pressure

Question 17

Structure and function of Veins

Answer 17

carry blood to the heart (always de-oxygenated apart from the pulmonary vein which goes from the lungs to the heart)
Have thin walls
Have larger internal lumen
Contain blood under low pressure
Have valves to prevent blood flowing backwards

Question 18

Structure and function of Capillaries

Answer 18

found in the muscles and lungs
Microscopic – one cell thick
Very low blood pressure
Where gas exchange takes place. Oxygen passes through the capillary wall and into the tissues, carbon dioxide passes from the tissues into the blood

Question 19

How does heart rate change during exercise?

Answer 19

It gets faster because the heart is trying to pump blood and oxygen to the needed muscles. Your muscles need ATP which is formed by respiration and need oxygen. This aerobic respiration. When you don’t get enough oxygen lactic acid is formed which anaerobic respiration.

Question 20

How does the circulatory system work?

Answer 20

The pulmonary artery takes de-oxygenated blood from the right ventricle of the heart to the lungs to get oxygenated.
The pulmonary vein then takes oxygenated blood from the lungs to the left atrium.
The left atrium through the atrioventricular valves into the left ventricle then into the aorta which leads to the rest of the body
The aorta goes to the hepatic artery for liver, renal artery for Kidney and for the lower body and legs.
Once the oxygenated blood becomes de-oxygenated it comes back up the inferior Vena Cava or down the Superior Vena cava (lower body) into the right atrium and back to the right ventricle to where it started