transport in animals

Question 1

The circulatory system is

Answer 1

a system of blood vessels with a pump and valves to ensure one-way flow of blood

Question 2

fish circulatory system

Answer 2

Fish have a two chambered heart and a single circulation This means that for every one circuit of the body, the blood passes through the heart once

Question 3

Double circulation in mammals

Answer 3

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 4

Advantages of a Double Circulation

Answer 4

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 5

the heart basics

Answer 5

The heart is labelled as if it was in the chest so what is your left on a diagram is actually the right hand side and vice versa

The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs

The left side of the heart receives oxygenated blood from the lungs and pumps it to the body

Blood is pumped towards the heart in veins and away from the heart in arteries

The two sides of the heart are separated by a muscle wall called the septum

The heart is made of muscle tissue which is supplied with blood by the coronary arteries

Question 6

Answer 6

Question 7

Arteries carry blood … the heart

Answer 7

Away from

Question 8

structure heart

Answer 8

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 9

Answer 9

Question 10

The Function of the Valves

Answer 10

The basic function of all valves is to prevent blood flowing backwards

There are two sets of valves in the heart:

The atrioventricular valves separate the atria from the ventricles

The valve in the right side of the heart is called the TRICUSPID and the valve in 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 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 11

Pathway of Blood through the Heart

Answer 11

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 semi lunar 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 semi lunar valve in the aorta prevents the blood flowing back down into the heart

Question 12

Exercise & Heart Rate

Answer 12

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)

To investigate the effects of exercise on heart rate, record the pulse rate at rest for a minute

Immediately after they do some exercise, record the pulse rate every minute until it returns to the resting rate

This experiment will show that during exercise the heart rate increases and may take several minutes to return to normal

Question 13

Why does Heart Rate Increase during Exercise?

Answer 13

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

Question 14

Coronary Heart Disease

Answer 14

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

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 15

Risk Factors for Coronary Heart Disease

Answer 15

Question 16

Reducing the risks of developing coronary heart disease:

Answer 16

Quit smoking

Reduce animal fats in diet and eat more fruits and vegetables – this will reduce cholesterol levels in the blood and help with weight loss if overweight

Exercise regularly – again, this will help with weight loss, decrease blood pressure and cholesterol levels and help reduce stress

Question 17

Treatment of coronary heart disease:

Answer 17

Aspirin can be taken daily to reduce the risk of blood clots forming in arteries

Surgical treatments include:

1. Angioplasty

A narrow catheter (tube) is threaded through the groin up to the blocked vessel

A tiny balloon inserted into the catheter is pushed up to the blocked vessel and then inflated

This flattens the plaque against the wall of the artery, clearing the blockage

To keep the artery clear, a stent (piece of metal / plastic mesh) is also inserted which pushes against the wall of the artery

Sometimes the stent is coated with a drug that slowly releases medication to prevent further build up of plaque

Inserting a stent into a blocked artery

2. Coronary bypass surgery

A piece of blood vessel is taken from the patient’s leg, arm, or chest and used to create a new passage for the flow of blood to the cardiac muscle, bypassing the blocked area

The number of bypass grafts gives rise to the name of the surgery, so a ‘triple heart bypass’ would mean three new bypass grafts being attached

Question 18

Arteries

Answer 18

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 19

Veins

Answer 19

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 20

Capillaries

Answer 20

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 21

How Structure of Blood Vessels is Adapted to their Function

Arteries

Answer 21

Have thick muscular walls containing elastic fibres to withstand 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 22

How Structure of Blood Vessels is Adapted to their Function

Veins

Answer 22

Have a large lumen as blood pressure is low

Contain valves to prevent the backflow of blood as it is under low pressure

Question 23

How Structure of Blood Vessels is Adapted to their Function

Capillaries

Answer 23

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 24

Arterioles & Venules

Answer 24

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 25

Shunt Vessels

Answer 25

Sometimes the cardiovascular system need to redistribute the blood to specific areas of the body

For example:

During exercise, more of it goes to the working muscles and less of it goes to other body organs such as the digestive system

When we are hot, more blood flows through the surface of the skin and when we are cold less blood flows through the surface of the skin

This redirection of blood flow is caused by the use of a vascular shunt vessel

The shunt vessels can open or close to control the amount of blood flowing to a specific area

Question 26

Circulation around the Body

Answer 26

lood is carried away from the heart and towards organs in arteries

These narrow to arterioles and then capillaries as they pass through the organ

The capillaries widen to venules and finally veins as they move away from the organs

Veins carry blood back towards the heart

Question 27

Answer 27

Question 28

Answer 28

Question 29

Lymph Fluid

Answer 29

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 fluid passes into the lymphatic system and becomes lymph fluid

Question 30

Lymph Vessels & Nodes

Answer 30

The lymphatic system is formed from a series of tubes which flow from tissues back to the heart

It connects with the blood system near to the heart, where lymph fluid is returned to the blood plasma

Lymph nodes are small clusters of lymphatic tissue found throughout the lymphatic system, especially in the neck and armpits

Large numbers of lymphocytes are found in lymph nodes

Tissues associated with the lymphatic system, such as bone marrow, produce these lymphocytes

Lymphocytes play an important role in defending the body against infection

Question 31

Blood consists of

Answer 31

red blood cells, white blood cells, platelets and plasma

Question 32

Answer 32

Question 33

Answer 33

Question 34

Answer 34

Question 35

White Blood Cells basics

Answer 35

White blood cells are part of the body’s immune system, defending against infection by pathogenic microorganisms

There are two main types, phagocytes and lymphocytes

Question 36

Phagocytes

Answer 36

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 37

Lymphocytes

Answer 37

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 38

Functions of the Parts of Blood

Answer 38

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

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

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

Platelets are involved in helping the blood to clot

Question 39

Blood Clotting

Answer 39

Platelets are fragments of cells which are involved in blood clotting and forming scabs where 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

When 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