Exchange in Animals

Question 1

What are the main features of a good transport system

Answer 1

A fluid for transport
a pump to create pressure for the fluid to reach all parts of the body
fast and sufficient exchange surfaces, and an effective transport system such as the capillaries veins and arteries that allow for the blood flow. The most effective systems will have a double circulatory system to have deoxy and oxy returning and leaving at the same time.

Question 2

What are the benefits of the closed circ over open

Answer 2

The closed can allow for a constant high pressure so that the blood can flow faster therefore the delivery and retrieval of O2 and CO2 are much faster. Also the transportation is independent of the animals movements unlike insects wings needing to move to pride the contraction needed to pump the transport medium.

Question 3

state the ways in which the artery are different to the veins walls

Answer 3

The Artery has thicker collagen fibres and a smaller lumen. The thick collagen fibres are there to cope with the high pressure produced by the heart and the smaller lumen is to ensure the blood is maintaining the high pressure throughout the body to ensure it reaches all parts.

Question 4

Why does the hydro static pressure drop after the blood has travelled away from the heart

Answer 4

The pressure is created by the heart during diastole and therefore as the blood gets further away the pressure excreted decreases.

Question 5

Why is the fetal haemoglobin to the left of the adult curve of haemoglobin

Answer 5

The fetal haems have a higher affinity for oxygen as they are getting their oxygen from the mother while in development. The fetal haem aquires there oxygen from the oxyhaemoglobin of the mother therefore needing a strong affinity to aquire any oxygen they can for themselves. ( if given a comparison question relate to both sides and you may need to give descriptions for each depending on the number of marks or q)

Question 6

Why would giving fetal haem to adults suffering with sickle cell anaemia be benificial

Answer 6

This is so that the adult though having less useful haems they can acquire a sufficient amount of oxygen and still function as usual as the fetal can deliver more oxygen than a sickle haem

Question 7

Describe the three layers of the Arteries

Answer 7

These are the tunica intima(small layer of elastic tissue)
Tunica media (thick layer of smooth muscle)
Tunica adventitia (think collagen and elastic firbres)

Question 8

What is the purpose of the arterioles

Answer 8

These are the connecting tube from arteries to capillaries they consist of a smooth muscle that can be contracted to restrict blood flow so thatit can be moved to areas of high O2 demand.

Question 9

Describe the formation of tissue fluid

Answer 9

There is a high hydro static pressure at the arteriole end and this forces blood fluid out the capillaries. This is mostly formed of plasma nutrient s and oxygen all the larger molecules such as the plasma proteins stay as well as the white blood cells and red.This fluid that leaves is tissue fluid this is used so that exchange occur across plasma membranes at. At the vein end the hydro static pressure decreases so the fluid return to the blood carrying the waste to be removed. Some of the fluid stays in the outside of the capillaries this is sent through the lymphatic system.

Question 10

Explain the movement of fluids

Answer 10

Check page 191 for the image for help if needed

Question 11

Draw a diagram of the heart labelling everything

Answer 11

See page 192 The diagram should include the R / L ventricles R /L atria , Semi lunar valves , aorta , pulmonary artery and veins

Question 12

Describe and explain each of the three stages of the cardiac cycle

Answer 12

One of the stages is Ventricular systole - at this stage the ventricles contract squeezing the blood out of the heart into the arteries
After this it is diastole - this is where all of the muscle relaxes to increase its size for blood to enter into the arteries.
After this it is atrial systole this is where the blood is squeezed out of the atria into the two ventricles until they are full of blood.

Question 13

What are the roles of the atrio-ventricular valves treat like a 6 marker

Answer 13

The valves use the pressure in the ventricles and atria to determine whether they are open. After The ventricles have been emptied in Ventricular systole the pressure in the ventricles rapidly drops this then forces the valve open as the blood wants to flow into the area with less pressure. Once the ventricles are full the pressure is high enough to force the valves to close stopping the blood flow into the ventricles. To help the valves with this they have tendinous cords that prevent the valves turning inside out as the pressure exerted is very high.

Question 14

What are the roles of the semi-lunar valves and how do they fulfil them

Answer 14

The semi lunar valves are in the arteries to prevent back flow of blood. They also work with pressure so when the ventricles fill up after atrial systole they have a higher pressure than the arteries and then the valves are forced open.

Question 15

Explain the points of the graph for pressure

Answer 15

The top line is the aortic pressure this is only affected by the ventricles pressure. When the pressure spikes in the ventricles the pressure increases in the arteries therefore creating the spike on the graph
The ventricular pressure spike at the opening of the the atria ventricular valves as they begin to build up and then the ventricles contract. then at diastole the pressure decreases as the muscles relax this occurs in diastole.
The atrial pressure is quite low. it changes when the atrial valves open and close as the pressure deceases and increases at these values as the blood flows in and out.

Question 16

What is the coordination of the cardiac cycle

Answer 16

The heart is myogenic as it can initiate its own contraction. Both the atria and ventricles contractions are synchronised if not they are in fibrillation.
There is a wave of excitation that is generated by the sino atrial node that i sent through the walls of both atria so that the muscle contracts during atrial systole. After this the atrioventricular node delays the signal for ventricular contraction so that both ventricles can fill before hand. Once the signal is sent out it travels down the purkyne tissue souring the ventricles to cause the contraction during ventricular systole. This means that they contract from the base of the heart upwards so the blood travels in the correct direction.

Question 17

What is the name of a slow heart rate on an electrocardiogram

Answer 17

This is known as bradycardia

Question 18

What is the name given for a fast heart rate

Answer 18

Tachycardia

Question 19

What is meant by the term atrial fibrillation

Answer 19

This is where the atrials are contracting faster than the ventricles

Question 20

Ectopic heartbeat

Answer 20

this is where the heart beat is irregular

Question 21

How do you recognise these on a graph

Answer 21

The slow and very delayed heartbeat is the Brady, the fast heart beat is the trachy, the out of order pressure reading is the atrial and the out of order spikes is the ectopic.

Question 22

Complete the following passage answers on the other side.
Large,active organisms need a circulatory system because they have a small ………………… . Haemoglobin is a pigment found in red blood cells. These cells are also known as …………………. . Haemoglobin has a high ………………….. for oxygen. In the lungs , the haemoglobin associates with oxygen to form …………….. . IN respiring tissues , the oxygen is released by dissociation. In very active tissues the amount of oxygen released can be increased by the presence of more ……….. . this is called the …… effect

Answer 22

Surface area to volume ratio
erythrocytes
affinity
oxyhaemoglobin
carbon dioxide
bohr

Question 23

State two reasons why a blood smear would be stained

Answer 23

This is so the cells are more visible and so that different parts within the cell can be differentiated.

Question 24

Explain the benefits to the Bohr effect

Answer 24

The body produces a lot of carbon dioxide increasing the amount of oxygen needed in those particular areas so that oxygen dissociates in the areas that are respiring a lot more than the other areas.

Question 25

What are the three ways in which carbon dioxide is transported around the body

Answer 25

This is 5% is dissolved directly into the plasma
10% is combined directly with haemoglobin to form carbaminohaemoglobin
85% is transported in the form of hydrogen carbonate ions.

Question 26

How are hydrogen carbonate ions formed

Answer 26

These are formed by firstly CO2 is diffused out of the blood plasma into the red blood cell. This is then reacted to the water in the cell to produce carbonic acid this is then separated into a H+ ion and hydrogencarbonate ion. The H+ are associated with the haemoglobin and removed from the cell to protect the cell from becoming to acidic, this association produces haemoglobinic acid . To prevent the pH of the cell changing chloride ions are added and removed depending on when they are needed.