Transport in Animals

Question 1

Explain Circulatory systems in Mammals

Answer 1

Mammals have a four-chambered heart and a double circulation
This means that for every one circuit of the body, the blood passes through the heart twice
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)

Question 2

Advantages of Double Circulation

Answer 2

Blood travelling through the small capillaries in the lungs loses a lot of pressure that was given to it by the pumping of the heart, meaning it cannot travel as fast
By returning the blood to the heart after going through the lungs its pressure can be raised again before sending it to the body, meaning cells can be supplied with the oxygen and glucose they need for respiration faster and more frequently

Question 3

How do we monitor the activity of Heart?

Answer 3

Heart activity can be monitored by using an ECG, measuring pulse rate or listening to the sounds of valves closing using a stethoscope
Heart rate (and pulse rate) is measured in beats per minute (bpm)

Question 4

Explain Coronary arteries

Answer 4

The heart is made of muscle cells that need their own supply of blood to deliver oxygen, glucose and other nutrients and remove carbon dioxide and other waste products
The blood is supplied by the coronary arteries
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

Question 5

Difference between partial Blockage and complete Blockage

Answer 5

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

Question 6

What are the structures of Heart

Answer 6

The ventricles have thicker muscle walls than the atria as they are pumping blood out of the heart and so need to generate a higher pressure
The left ventricle has a thicker muscle wall than the right ventricle as it has to pump blood at high pressure around the entire body, whereas the right ventricle is pumping blood at lower pressure to the lungs
The septum separates the two sides of the heart and so prevents mixing of oxygenated and deoxygenated blood

Question 7

Explain the function of valves

Answer 7

The basic function of all valves is to prevent blood from flowing backwards
There are two sets of valves in the heart:
The atrioventricular valves separate the atria from the ventricles
The valve on the right side of the heart is called the TRICUSPID and the valve on the left side is called the BICUSPID
These valves are pushed open when the atria contract but when the ventricles contract they are pushed shut to prevent blood from flowing back into the atria
The semilunar valves are found in the two blood arteries that come out of the top of the heart
They are unusual in that they are the only two arteries in the body that contain valves
These valves open when the ventricles contract so blood squeezes past them out of the heart, but then shut to avoid blood flowing back into the heart

Question 8

Explain the Function of Heart

Answer 8

Deoxygenated blood coming from the body flows into the right atrium via the vena cava
Once the right atrium has filled with blood the heart gives a little beat and the blood is pushed through the tricuspid (atrioventricular) valve into the right ventricle
The walls of the ventricle contract and the blood is pushed into the pulmonary artery through the semilunar valve which prevents blood flowing backwards into the heart
The blood travels to the lungs and moves through the capillaries past the alveoli where gas exchange takes place (this is why there has to be low pressure on this side of the heart – blood is going directly to capillaries which would burst under higher pressure)
Oxygen-rich blood returns to the left atrium via the pulmonary vein
It passes through the bicuspid (atrioventricular) valve into the left ventricle
The thicker muscle walls of the ventricle contract strongly to push the blood forcefully into the aorta and all the way around the body
The semilunar valve in the aorta prevents the blood flowing back down into the heart

Question 9

Explain the effect of physical activity on heart

Answer 9

So that sufficient blood is taken to the working muscles to provide them with enough nutrients and oxygen for increased respiration
An increase in heart rate also allows for waste products to be removed at a faster rate
Following exercise, the heart continues to beat faster for a while to ensure that all excess waste products are removed from muscle cells
It is also likely that muscle cells have been respiring anaerobically during exercise and so have built up an oxygen debt
This needs to be ‘repaid’ following exercise and so the heart continues to beat faster to ensure that extra oxygen is still being delivered to muscle cells
The extra oxygen is used to break down the lactic acid that has been built up in cells as a result of anaerobic respiration

Question 10

Explain Arteries

Answer 10

Carry blood at high pressure away from the heart
Carry oxygenated blood (other than the pulmonary artery)
Have thick muscular walls containing elastic fibres
Have a narrow lumen
Speed of flow is fast

Question 11

Explain Veins

Answer 11

Carry blood at low pressure towards the heart
Carry deoxygenated blood (other than the pulmonary vein)
Have thin walls
Have a large lumen
Contain valves
Speed of flow is slow

Question 12

Explain Capillaries

Answer 12

Carry blood at low pressure within tissues
Carry both oxygenated and deoxygenated blood
Have walls that are one cell thick
Have ‘leaky’ walls
Speed of flow is slow

Question 13

Adaptations and Function of Arteries

Answer 13

Have thick muscular walls containing elastic fibres to withstand the high pressure of blood and maintain the blood pressure as it recoils after the blood has passed through
Have a narrow lumen to maintain high pressure

Question 14

Adaptation and Function of Veins

Answer 14

Have a large lumen as blood pressure is low
Contain valves to prevent the backflow of blood as it is under low pressure

Question 15

Adaptation and function of capillaries

Answer 15

Have walls that are one cell thick so that substances can easily diffuse in and out of them
Have ‘leaky’ walls so that blood plasma can leak out and form tissue fluid surrounding cells

Question 16

Explain arterioles and Venules

Answer 16

As arteries divide more as they get further away from the heart, they get narrower
The narrow vessels that connect arteries to capillaries are called arterioles
Veins also get narrower the further away they are from the heart
The narrow vessels that connect capillaries to veins are called venules

Question 17

What are the main blood vessel

Answer 17

The hepatic artery brings oxygenated blood from the heart to the liver
The hepatic vein brings deoxygenated blood from the liver back to the heart
The hepatic portal vein transports deoxygenated blood from the gut to the liver

Question 18

Explain the structure of Red Blood Cell

Answer 18

Biconcave Disks containing no nucleus but plenty of pretty protein haemoglobin

Question 19

Explain White Blood Cell

Answer 19

Large Cells Containing Big Nuclues, different types have sligthly different structures and functions

Question 20

Explain the function of Red Blood Cell

Answer 20

Red blood cells transport oxygen around the body from the lungs to cells which require it for aerobic respiration
They carry the oxygen in the form of oxyhaemoglobin

Question 21

Explain the function of White Blood Cell

Answer 21

White blood cells defend the body against infection by pathogens by carrying out phagocytosis and antibody production

Question 22

Explain the function of Plasma

Answer 22

Plasma is important for the transport of carbon dioxide, digested food (nutrients), urea, mineral ions, hormones and heat energy

Question 23

Explain the function of Platelets

Answer 23

Platelets are involved in helping the blood to clot

Question 24

Explain Phagocytosis

Answer 24

Carry out phagocytosis by engulfing and digesting pathogens
Phagocytes have a sensitive cell surface membrane that can detect chemicals produced by pathogenic cells
Once they encounter the pathogenic cell, they will engulf it and release digestive enzymes to digest it
They can be easily recognised under the microscope by their multi-lobed nucleus and their granular cytoplasm

Question 25

Explain Lymphocytosis

Answer 25

Produce antibodies to destroy pathogenic cells and antitoxins to neutralise toxins released by pathogens
They can easily be recognised under the microscope by their large round nucleus which takes up nearly the whole cell and their clear, non-granular cytoplasm

Question 26

Explain Conversion of Fibrinogen

Answer 26

Platelets are fragments of cells which are involved in blood clotting and forming scabs where the skin has been cut or punctured
Blood clotting prevents continued / significant blood loss from wounds
Scab formation seals the wound with an insoluble patch that prevents entry of microorganisms that could cause infection
It remains in place until new skin has grown underneath it, sealing the skin again
hen the skin is broken (i.e. there is a wound) platelets arrive to stop the bleeding
A series of reactions occur within the blood plasma
Platelets release chemicals that cause soluble fibrinogen proteins to convert into insoluble fibrin and form an insoluble mesh across the wound, trapping red blood cells and therefore forming a clot
The clot eventually dries and develops into a scab to protect the wound from bacteria entering