Transport in Animals

Question 1

What is a double circulatory system

Answer 1

The blood passes through the heart twice for each complete circuit of the body

Question 2

What is a single circulatory system

Answer 2

The blood passes through the heart once for each complete circuit of the body

Question 3

What is the need for the cardiovascular system

Answer 3

To transport nutrients, hormones oxygen and to remove waste metabolites such as CO2

Question 4

What do animals need a specialised transport system

Answer 4

Large animals have a small surface area to volume ratio and a high metabolic rate. This means simple diffusion will not be sufficient enough to meet their metabolic demands.

Question 5

What are some features of a good transport system

Answer 5

A fluid or medium to carry nutrients
A pump to create pressure in order to push fluid round the body
Exchange surfaces that can allow substances to enter and be removed from the blood

Question 6

What are advantages of a double circulatory system

Answer 6

Oxygen and nutrients will get delivered to parts of the body where it’s needed quickly due to pressure generated by the heart. The heart can increase the pressure once it’s been oxygenated at the lungs

The systemic pressure can be much higher as it needs to supply blood to the rest of the body. Pulmonary pressure has to be lower so it doesn’t damage capillaries at the lungs

In a single circulatory system blood pressure falls as it passes through the capillaries so blood will have a low pressure as it flows to the body

Question 7

What is a open circulatory system what are the disadvantages

Answer 7

Blood isn’t enclosed in blood vessels example being insects where their blood is called haemolymph. Its cells are bathed in fluid.

Blood pressure and flow is low
The blood isn’t directed so circulation can be affected by body movements or lack of movements

Question 8

What are elastic fibres, smooth muscle and collagen

Answer 8

Elastic fibres - stretch and recoil to even out the surge and maintain the pressure

Smooth muscle - contract and relax to maintain blood flow
Relaxing is vasodilation (more blood flow)
Contracting is vasoconstriction (less blood flow)

Collagen is a thick layer of fibrous protein that can withstand the high pressure of the blood

Question 9

What is a closed circulatory system and what are some advantages

Answer 9

Blood is enclosed in vessels, a separate fluid called tissue fluid bathes the cells.

The blood is under higher pressure
Their is a rapid delivery of oxygen and nutrients and removal of waste metabolites
Circulation is unaffected by body movements

Question 10

What do all blood vessels have in their tunica intima

Answer 10

All vessels having a lining of endothelium cells.

They are smooth in order to reduce friction

Question 11

Describe the function and structure of arteries

Answer 11

Function
To carry blood away from the heart. The vessels are called the aorta and pulmonary artery

Structure
As the blood leaving the heart is under high pressure the artery wall has to be thick
Tunica intima - Layer of endothelium
Tunica media - Thick layers of smooth muscle
Tunica externa - Thick layer of collagen and elastic tissue
Narrow lumen

Further away from the heart they contain more smooth muscle

Question 12

Describe the function and structure of arteries

Answer 12

Function
To divert the blood from the arteries into the capillaries

Structure
Contain smooth muscle which can constrict its diameter to divert the blood.
Resistance is increased and the rate of flow of blood is reduced

Question 13

Describe the function and structure of capillaries

Answer 13

Function
They allow exchange of materials between tissue fluid and the blood

Structure
Consist of squamous epithelial cells which are one cell thick which provide a short diffusion pathway
Narrow lumen which allows one red blood cell to pass through at a time maximising rate of diffusion in a given time
Walls contain pores allow plasma and dissolved substances to leave the blood

Question 14

Describe the function and structure of venules

Answer 14

Function
Collect the blood from the capillary bed and return the blood to the veins

Structure
Consists of a thin layers of muscle and elastic tissue outside the endothelium and a thin layer of collagen

Question 15

Describe the function and structure of veins

Answer 15

Function
Return the blood back to the heart

Structure
The blood is under low pressure so doesn’t need to be thick
Lumen is relatively large in order to easy the flow of blood
Have thinner layers of elastic tissue, collagen and smooth muscle
They contain valves to prevent the backflow of blood - these thin walls are surrounded by skeletal muscles that contract forcing the blood in the correct direction

Question 16

How is plasma different from tissue fluid

Answer 16

Large molecules can’t pass through the capillaries into tissue fluid
e.g. large plasma proteins, white blood cells

Question 17

Describe the formation of tissue fluid

Answer 17

Arteriole end
The hydrostatic pressure is higher then the oncotic pressure so the net movement of blood out forming tissue fluid. The fluid that is being pushed out leaves through gaps in the endothelium.
The blood leaving contains O2 and nutrients dissolved in it and it’s exchanged with CO2 and other waste

Venule end
The oncotic pressure remains the same as the large plasma proteins remain in the capillaries
The hydrostatic pressure is much lower due to loss of fluid so the net movement of tissue fluid is to enter the capillaries reforming plasma

Lymphatic system
Not all of the fluid renters the capillaries some is drained into the lymphatic system.
It is then returned to the blood system in the subclavian vein in the chest

Question 18

Describe the composition of the fluid in the lymphatic system

Answer 18

The fluid is called lymph, it is similar composition to tissue fluid but will contain more lymphocytes as they are produced in the lymph nodes
Lymph nodes are swellings found along the lymphatic system
If a tissue is infected that capillaries become more leaky and fluid is directed towards the lymph nodes directing bacteria towards it.
This is part of the non specific immune response

Question 19

What muscle is external of the heart and what vessel supplies this with oxygen and nutrients

Answer 19

Cardiac muscle and coronary artery supplies it

Question 20

List the internal features of a heart starting at the top and going clockwise

Answer 20

Consists of 4 chambers 2 ventricles and 2 atriums
When describing the heart the left side is on the right and the right side is on the left

Aorta, left atrium, pulmonary vein, left ventricle, right ventricle, vena cava, right atrium and pulmonary artery.

Contains a tri (right) and bi (left) cuspid valve that separate the atria and ventricles

Contains semi lunar valves separating the arteries and ventricles

A septum separates both sides and the bottom of the heart is called the apex

Question 21

Which side of the heart do we usually measure heat changes from

Answer 21

We measure the pressure changes at the left side of the heart.
The left ventricle has a much thicker wall as it has to has to generate more force in order to contract and send the blood around the body
Therefore systemic pressure is bigger then pulmonary pressure

Question 22

Describe the blood flow in the heart

Answer 22

Deoxygenated blood enters the right atrium from the vena cava flows to the right ventricle and out of the pulmonary artery
The blood gets oxygenated at the lungs and returns to the blood via the pulmonary vein.
The blood enters the left atrium then the right ventricle and out of aorta to be sent to the rest of the body.

Question 23

Describe the cardiac cycle including pressure changes

Answer 23

Atrial systole - The atrium is contracting and the ventricle is relaxing therefore the pressure
is higher in the atria then the ventricles. As a result the a-v valves are open
and blood is emptied into the ventricles

Ventricular systole - The ventricles are contacting and the atria are relaxing. The pressure in
the ventricles is higher then atrial and aortic pressure so a-v valves
close and the semi lunar valves open

Diastole - Both atria and ventricles are relaxing but pressure is higher in the atria as blood
enters from the veins, the a-v valves open and blood enters the ventricles
passively

The cycle starts all over again

Atria pressure is always relatively low due to its thinner walls

Question 24

Why is blood flow higher when you are standing up as opposed to sitting down

Answer 24

Blood flow has to move against gravity up to your head so blood flow increases

Question 25

Describe the electrical activity of the heart up to the AVN

Answer 25

The SAN initiates the wave of depolarisation which spreads over the atrial walls forcing them to contract
The wave of depolarisation reaches non conductive tissue (collagen) at the base of the atria so the wave has to go to the AVN. It’s the only route that can be taken
The wave is delayed at the AVN to allow the atria to fully contract

Question 26

Describe the electrical activity of the heart after the AVN

Answer 26

The wave of depolarisation is sent down the bundle of HIS down the septum towards the apex.
The waves then spread outwards and up purkinje fibres causing the ventricles to contract from base upwards so all of the blood is pushed to the arteries

Question 27

What does ECG stand for, how would you recognise a healthy persons one

Answer 27

Electrocardiograms

It consists of a
P - atrial systole
QRS - ventricular systole 
T - diastole
waves

Question 28

What are the types of other ECG’S

Answer 28

Tachycardia - Fast heartbeat
Bradycardia - Slow heartbeat
Ectopic - Heat skips or adds a beat
Fibrillation - Irregular heartbeat tends to fast

Question 29

Describe a typical graph of saturation against pO2

Answer 29

The curve is a sigmoid
At low pO2 there is a low saturation as this is usually at respiring cells and tissues where oxygen needs to be unloaded
As pO2 increase saturation increases even quicker due to cooperative binding but then levels off as a higher pO2 is needed to become 100% saturated

Question 30

How does fetal haemoglobin differ from adult haemoglobin

Answer 30

In the placenta there is a lower pO2 of oxygen so fetal haemoglobin needs to have a higher affinity then adult haemoglobin so it can bind to it when the oxygen is unloaded

Question 31

What are the three ways of transport of CO2

Answer 31

In the plasma
Convert to carbonic acid
carbamino haemoglobinic acid

Question 32

What is the effect when CO2 is present at respiring cells what happens

Answer 32

Co2 diffuses into erythrocytes and combines with water to form carbonic acid
This reaction is catalysed by carbonic anhydrase
Carbonic acid dissociates into H+ ions and HCO3-
The HCO3- diffuses out and is exchanged with Cl- (chloride shift)
The Hb has a lower affinity for oxygen so binds with H+ forming HHB
Also acts as a buffer
As a result oxygen is unloaded at the cells by oxyhaemoglobin

Question 33

What is the effect when CO2 is present at respiring cells what happens

Answer 33

Co2 diffuses into erythrocytes and combines with water to form carbonic acid
This reaction is catalysed by carbonic anhydrase
Carbonic acid dissociates into H+ ions and HCO3-
The HCO3- diffuses out and is exchanged with Cl- (chloride shift)
The Hb has a lower affinity for oxygen so binds with H+ forming HHB
Also acts as a buffer
As a result oxygen is unloaded at the cells by oxyhaemoglobin