Circulatory system

Question 1

What is the function of Plasma

Answer 1

Transport of CO2, digested food, urea, mineral ions, hormones and heat energy

Question 2

What is the function of red blood cells

Answer 2

Transport of oxygen in the form oxyhaemoglobin across the body

Question 3

What is the function of white blood cells

Answer 3

Defend the body against pathogens by carrying out phagocytosis and antibody production

Question 4

What do platelets do

Answer 4

Help blood to clot

Question 5

What are red blood cells and where are they made

Answer 5

Highly specialized cell made in bone marrow

Question 6

Name 4 adaptations of red blood cells and what are they used for?

Answer 6

Biconcave shape for high surface area to volume ratio to create fast and efficient diffusion of gases
Lacks a nucleus and other large organelles to give more space for haemoglobin so that more oxygen can be transported
Has Haemoglobin that combines with oxygen to form oxyhaemoglobin
Thin cell wall so that short diffusion distance to the centre of the cell

Question 7

Name 2 types of white blood cells

Answer 7

Phagocytes and Lymphocytes

Question 8

How can Phagocytes be recognized

Answer 8

Through their multi-lobed nucleus and granular cytoplasm

Question 9

How can Lymphocytes be recognized

Answer 9

Through their large round nucleus and non-granular cytoplasm

Question 10

What are 2 ways that Lymphocytes take action

Answer 10

By making antibodies stick to antigen and destroy the pathogen
Some Lymphocytes make memory cells without killing the pathogen. This allows the Lymphocytes to make specific antibodies when a re-infection takes place

Question 11

Lymphocytes also produce _________ to neutralize _______ released by the pathogens

Answer 11

Lymphocytes also produce antitoxins to neutralize toxins released by the pathogens

Question 12

What are antibodies

Answer 12

Y shaped proteins with a shape that are specific to the antigens on the surface of the pathogen

Question 13

What is the primary immune response

Answer 13

Production of antibodies after the first exposure to a foreign antigen
Some Lymphocytes convert into memory cells without killing pathogens

Question 14

How does the Lymphocyte destroy the pathogen by antibodies

Answer 14

Causing bacteria to stick together
Acting as a label so that the phagocyte can recognize it
Causing bacteria to burst open
Neutralizing poisons released by pathogens

Question 15

What is the Secondary immune response

Answer 15

Memory cells recognize the microorganism that re-infects a person and starts to reproduce and produce a large number of antibodies rapidly

Question 16

What happens through Vaccination

Answer 16

A person can be given artificial immunity through an agent that carries the same antigen as a specific pathogen
Lymphocytes recognizes the antigen and multiply exactly as if that microorganisms had entered the bloodstream, they produce memory cells and make the person immune to the diseases
If a person comes in contact with a real pathogen they will experience a secondary immune response

Question 17

How does a blood clot form?

Answer 17

When the skin is cut, exposure to air stimulates the platelets and the damaged tissues to produce a chemical
This chemical causes fibrinogen (soluble plasma protein) to form fibrin (insoluble plasma protein)
Fibrin forms a network across the wound in which red blood cells become trapped
This forms a clot that turns into a scab

Question 18

Name 5 things that arteries have or do

Answer 18

Carry blood at high pressure away from the heart
Carry oxygenated blood
Have a narrow lumen to maintain high blood pressure
Have thick walls containing elastic fibers to withstand and maintain high pressure of blood
The speed of blood flow is fast

Question 19

Name 6 things that veins have or do

Answer 19

Carry blood at low pressure away from the heart
Carry deoxygenated blood
Have thin walls with fewer muscles and fibers
Large lumen so that blood pressure is slow so more volume of blood can be contained
Valves to prevent the backflow of blood
The speed of blood flow is slow

Question 20

Name 5 things that capillaries have or do

Answer 20

Carry blood at low pressure within tissues/organs so that there is more time for an exchange
Carry both oxygenated and deoxygenated blood
Speed of blood flow is slow for better diffusion
Have one cell thick walls so that diffusion distances are shorter
Have ‘leaky’ walls for better exchange so that blood plasma can leak out and form tissue fluid surrounding cells

Question 21

What is Lymph/Tissue fluid

Answer 21

Tissue fluid is a fluid surrounding the cells of a tissue.
It is leaked plasma - Plasma from the blood capillaries move to the tissue through gaps in the walls and become tissue fluid
Supplies cells with O2 and nutrients and takes away waste products such as CO2
The walls of the capillaries are so thin that water, dissolved solutes and dissolved gases easily leak out of them/pass through the walls from the plasma into the tissue fluid surrounding the cells
Cells exchange materials (such as water, oxygen, glucose, carbon dioxide, mineral ions) across their cell membranes with the tissue fluid surrounding them by diffusion, osmosis or active transport
More fluid leaks out of the capillaries than is returned to them, and this excess of leaked fluid surrounding the capillaries then passes into the lymphatic system, becoming lymph fluid

Question 22

Why simple unicellular organisms can rely on diffusion for movement of substances in and out of the cell?

Answer 22

They have larger surface area to volume ratio than multicellular organisms
They can have more nutrients such as oxygen, glucose, that their volume demands through simple diffusion

Question 23

Why large organisms are evolved with special gas exchange organs or circulatory system?

Answer 23

Surface area to volume ratio is low and their distance within the body is larger and diffusion is inefficient to transport materials in the body
Large organisms use special gas exchange organs and circulatory system that carry nutrients to each cell of the body

Question 24

What are the differences in circulatory system between a human and a fish

Answer 24

Fish have a single circulatory system while humans have a double circulatory system
Fish: Blood pumps from heart –> Gas exchange organ (gills) –> rest of the body
Humans: Blood pumps from the heart–> lungs–>heart–>body

Question 25

What is double circulation and why is it more efficient that single circulation?

Answer 25

For every one circuit of the body, the blood passes through the heart twice
Heart pumps the blood twice so pressure is maintained
Blood travels faster to organs

Question 26

What is the structure of the human heart?

Answer 26

It is divided into left and right by a wall called septum
Heart has 4 chambers; upper left and right atrium and lower left and right ventricles
Wall of left ventricle is much thicker than the wall of right ventricle as right ventricle only has to pump blood to the lungs while the left ventricle has to pump blood to the rest of the body
The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs (the pulmonary circulation)
The left side of the heart receives oxygenated blood from the lungs and pumps it to the body (the systemic circulation)
The heart contains valves to prevent the blood flowing backwards and ensure that blood can flow only in one direction through the heart.
* Right side has a tricuspid valve (a valve with three flaps)
* Left side has a bicuspid valve (a valve with two flaps)
* Both sides have semi-lunar valves (at the entrances to the pulmonary artery and aorta)
The wall of the atria is thin because they should be able to stretched to receive blood as it returns to the heart but can contract with enough force to push blood through the bi and tricuspid valves into the ventricles
The walls of the heart are made out of cardiac muscle; which contract and relax continuously without getting fatigued
The cardiac muscle has its own blood supply- Coronary circulation. The coronary arteries which supply the heart muscle with oxygen and nutrients. Blood returned to right atrium via coronary vein

Question 27

What is the hole in the heart condition

Answer 27

Some babies have this condition
This allows a connection between left and right atrium at certain places in the septum
It allows oxygenated and deoxygenated blood to mix resulting in inefficient gas exchange and transport of nutrients

Question 28

What is cardiac cycle

Answer 28

The cardiac cycle is defined as a sequence of alternating contraction (systole) and relaxation (diastole) of the atria and ventricles in order to pump blood throughout the body.
It starts at the beginning of one heartbeat and ends at the beginning of another.
A single heart beat consists with one cycle of systole and diastole, which lasts 0.8 s in human – known as cardiac cycle
The heart beats at approximately 70 beats in one minute (pulse rate) and each beat is one cardiac cycle

Question 29

What are the 3 events of the atrial systole of the cardiac cycle

Answer 29

1. Atrial systole
2. Ventricular systole
3. Cardiac diastole

Question 30

What are coronary heart disease

Answer 30

If a coronary artery becomes partially or completely blocked by fatty deposits called ‘plaques’ (mainly formed from cholesterol), the arteries are not as elastic as they should be and therefore cannot stretch to accommodate the blood which is being forced through them – leading to coronary heart disease
Partial blockage of the coronary arteries creates a restricted blood flow to the cardiac muscle cells and results in severe chest pains called angina
Complete blockage means cells in that area of the heart will not be able to respire and can no longer contract, leading to a heart attack
Coronary arteries are among the narrowest arteries in the body and easily blocked by a build–up of fatty substances such as cholesterol on the walls of coronary arteries and the lumen of the artery gets narrower

Question 31

What happens if there is a plaque formation

Answer 31

Blood supply is cut off
Affected muscle is no longer able to receive oxygen and glucose and it cannot respire and release energy
Cardiac muscle is unable to contract, resulting in heart attack and it is called coronary heart disease

Question 32

What are factors that many increase risk of developing coronary heart disease

Answer 32

Heredity: inherit the tendency to develop CHD
High blood pressure: puts more pressure on the heart
Diet: eating large amount of saturated fat which is likely to raise cholesterol level
Smoking- raise blood pressure and make blood clots easier to form
Stress- increase blood pressure
Lack of exercise- regular exercise helps reduce blood pressure and strengthen the heart

Question 33

Why does the heart rate increase during exercise?

Answer 33

So that sufficient blood is taken to the working muscles to provide them with enough nutrients and oxygen for increased respiration
Increase in heart rate allows waste products to be removed at a faster rate
Muscle cells have been respiring anaerobically during exercise and have built up an oxygen debt
This needs to be repaid following exercise and so heart beat faster to ensure that extra oxygen is still being delivered to muscle cells
Extra oxygen is used to break down the lactic acid that has been built in cells as a result of anaerobic respiration