Transport in Animals

Name:

Content: Students will be able to...

explain the need for transport systems in multicellular animals in terms of size, level of activity and surface area:volume ratio explain the meaning of the terms single circulatory system and double circulatory system, with reference to the circulatory systems of fish and mammals; explain the meaning of the terms open circulatory system and closed circulatory system, with reference to the circulatory systems of insects and fish; describe, with the aid of diagrams and photographs, the external and internal structure of the mammalian heart; explain, with the aid of diagrams, the differences in the thickness of the walls of the different chambers of the heart in terms of their functions; describe the cardiac cycle, with reference to the action of the valves in the heart; describe how heart action is coordinated with reference to the sinoatrial node (SAN), the atrioventricular node (AVN) and the Purkyne tissue; interpret and explain electrocardiogram (ECG) traces, with reference to normal and abnormal heart activity; describe, with the aid of diagrams and photographs, the structures and functions of arteries, veins and capillaries; explain the differences between blood, tissue fluid and lymph; describe how tissue fluid is formed from plasma; describe the role of haemoglobin in carrying oxygen and carbon dioxide; describe and explain the significance of the dissociation curves of adult oxyhaemoglobin at different carbon dioxide levels (the Bohr effect); explain the significance of the different affinities of fetal haemoglobin and adult haemoglobin for oxygen.

Collection of quantitative data: Investigate surface area to volume relationships using agar blocks and dye;

Collection and presentation of qualitative (descriptive) data: Make measurements and annotated drawings during a heart dissection

1

Transport in Animals

Key Term Definition/Example/Diagram/FormulaSurface Area to volume ratio

Single circulatory System

Double Circulatory System

Relationship Between Surface Area and VolumeSide Length

(mm)Surface Area

(mm2)Volume (mm3) SA:V

1 6 1 6:1

2 24

4

2

Single Circulatory

Double Circulatory System

3

1. Figs. 1 and 2 are diagrams to show the internal structure of the heart and its associated circulatory system in a simplified form. Fig. 1 represents the system for a mammal and Fig. 2 that for a frog (an amphibian).

capillaries inlungs

capillaries inrest of body

capillaries inlungs

capillaries inrest of body

mammal frog

Fig. 1 Fig. 2

Both systems are described as closed systems. The mammalian system is also described as a complete double circulation but the frog as a partial double circulation.

(i) State what is meant by a closed system.

.........................................................................................................................

.........................................................................................................................

[1]

4

(ii) Use the information in Fig. 1 and Fig. 2 to suggest why the mammalian system is called a complete double circulation whilst that of the frog is called a partial double circulation.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

[3]

(iii) Suggest why the system shown for the frog may be less effective at supplying the body tissues with oxygen.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

[2]

5

Heart Structure

Key TermDefinition/Example/Diagram/Formula

Atria

Ventricle

Vena Cava

Pulmonary Artery

Atrioventricular ValvesSemi-Lunar Valves

Septum

6

Heart dissectionSafetyAt the end of the practical, the hearts and any material cut from them should be wrapped up and disposed of safely. Students should wash their hands thoroughly with soap and hot water. Dissection instruments and boards should be washed with disinfectant.

Apparatus and materials• pig or sheep heart • blunt seeker• dissection board • scalpel• scissors • surgical gloves• forceps • disinfectant

IntroductionIn this practical, you will:

• identify the structures visible on the surface of the heart• trace the pathway taken by blood as it flows through the heart• dissect the heart to show how its structure enables it to carry out its function as a pump.

Procedure

1. Place the heart on a dissection board with the coronary vessels on the upper side. You should be looking at the heart as seen from the front of the animal (a ventral view), as shown in Figure 5.6 on page 65 of Biology 1. Check that the left ventricle is on the right-hand side – it will feel solid when pressed. The right ventricle feels softer.

2. Use the photographs and drawings on page 65 of Biology 1 to help you identify the following structures:

• left and right ventricles • pulmonary artery• left and right atria • vena cava• pulmonary veins • coronary arteries.

3. Cut away any surplus fat to expose the major blood vessels at the top of the heart.

4. Make a drawing of the heart to show the main external features. Draw a ventral view, with the apex at the bottom of the drawing. Label and add a scale your drawing.

7

5. Cut into the vena cava and then through the right atrium. From there cut into the wall of the right ventricle down to its base. Clear out any clotted blood. Open up the chambers and wash out with water if necessary.

6. Examine the valve between the right atrium and the right ventricle. Measure the thickness of the walls of the two chambers.

7. Trace the pathway taken by blood as it leaves the right ventricle through the pulmonary artery.

8. Cut down the pulmonary artery to expose the semilunar valves.

9. Make a drawing of your dissection of the right side of the heart. Label the drawing. Use annotations to describe the appearance of the structures you have drawn and their functions. Add a scale to your drawing.

10. Cut into the left atrium and then into the left ventricle as far as the apex of the heart. Open the chambers and clean out as before.

11. Examine the valve between the left atrium and the left ventricle. Measure the thickness of the walls of the two chambers.

12. Trace the pathway of blood as it leaves the left ventricle through the aorta.

13. Cut down the aorta to expose the semilunar valves. Find the origin of the coronary arteries in the aorta.

14. Make a drawing of your dissection of the left side of the heart. Label the drawing. Use annotations to describe the appearance of the structures you have drawn and their functions. Add a scale to your drawing.

8

15. Record all your measurements of wall thickness in a suitable way.

16. When you have finished, dispose of the dissected material as instructed, wash the dissection board and place the instruments into disinfectant. Wash your hands thoroughly.

Tasks:

1. Draw up a table to compare the structure and appearance of the four chambers of the heart.

2. In one complete circuit through the heart, how does the output of blood from any one of these chambers compare with that from the other chambers?

3. Explain how the valves you have displayed in your dissection ensure that blood flows through the heart.

4. Calculate the ratio between the thickness of the wall of the left ventricle and that of the wall of the right ventricle.

9

Past Paper Question

The diagram below shows the internal structure of the mammalian heart and associated blood vessels.

A

B

vena cava

septumPurkyne tissue

(i) State the name of structures A and B.

A .....................................................................................................................

B .....................................................................................................................

[2]

(ii) Use arrows on the diagram to show the direction of blood flow through the left side of the heart.

[1]

(iii) Suggest how the heart would be affected if the Purkyne tissue ceased to function.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

[2]

10

(iv) The septum shown on the diagram completely separates the left and right sides of the heart.

Explain why it is important that the two sides of the heart are completely separated.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

[2]

2. The diagram below shows an artery lying on the surface of living heart muscle as seen by an instrument called an endoscope. The lumen of the artery has become narrowed at the point labelled Y.

The Forum on Ischaemic Heart Disease.Reproduced by kind permission of Dr Graham Jackson,

Cardiology Unit, Guy’s and St Thomas’ Hospital.

(i) Name the artery shown in the diagram.

.........................................................................................................................

[1]

11

Cardiac Cycle

Key TermDefinition/Example/Diagram/Formula

Lub-dub

Systole

Diastole

Useful animation: http://library.med.utah.edu/kw/pharm/hyper_heart1.html

12

Atrial Systole

Ventricular Systole

Diastole

Past Paper Question 13

The cardiac cycle is the sequence of events which makes up one heart beat. The diagram below shows the events in the heart during one heart beat. The heart is viewed from the side.

X

YZ

In this question, one mark is available for the quality of spelling, punctuation and grammar.

Using the information in the diagram, describe the sequence of events involved in one heart beat.

You may annotate X, Y and Z in the diagram to help your answer. (Do not describe how the beat is initiated and controlled.)

(Allow one lined page).[6]

Quality of Written Communication [1]

[Total 7 marks]

..................................................................................................................................................................

14

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

..................................................................................................................................................................

Electrical Activity of the Heart

15

Key Term Definition/Example/Diagram/FormulaSinoatrial Node

Atrioventricular NodePurkyne Tissue

Electrocardiogram

The changes in electrical activity that occur in the muscle of the heart wall during the cardiac cycle can be recorded as an electrocardiogram (ECG).

Fig. 1 shows a normal ECG.

16

#

Past Paper Question

• P represents activity in the atrial walls.

• R represents the contraction of the ventricles.

• T represents the recovery of the ventricle walls.

Fig. 2 shows an ECG from a person who has entered a condition known as fibrillation.

Fibrillation should be treated rapidly to increase the chances of survival.

electrica l changeP

R

T P

0 0.1 0 .2 0 .3 0 .4 0.5 0 .6 0.7 0.8 0.9 1 .0

tim e/ s

17

Fig. 1

electrica l change

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

tim e/ s

Fig. 2

Using the information in Figs. 1 and 2, suggest why a person with a fibrillating heart is unlikely to survive for long if not treated.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

[Total 2 marks]

Blood Vessels

Key Term Definition/Example/Diagram/FormulaPeristalsis

Endothelium

Lumen

18

Arteries, Veins and Capillaries Venn

19

Things in common Major Differences

Past Paper Questions

20

1. The diagram below shows the changes in the pressure of blood as it flows through various parts of the mammalian blood system.

0

5

10

15

20

arteries arterioles venules veinscapillaries

pressure/ kP a

(a) The diagram shows that the pressure rises and falls in the arteries.

Explain what causes this rise and fall in pressure.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

[2]

(b) The diagram shows that:

• the rise and fall in pressure seen in the arteries is not evident by the time the blood enters the capillaries

• the pressure is much lower by the time the blood enters the capillaries.

Explain what causes the changes described above.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

[3]

(c) Explain why it is important that the pressure is lower by the time blood reaches the capillaries.

21

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

[2]

(d) The pressure in veins is very low. Explain how the blood in veins is returned to the heart.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

[2]

Tissue Fluid and Lymph

Key Term Definition/Example/Diagram/Formula

22

Plasma Proteins

Hydrostatic Pressure

Tissue Fluid

Leucocytes

23

Feature Blood Tissue Fluid Lymph

Cells

Proteins

Fats

Glucose

Amino Acids

Oxygen

Carbon Dioxide

Past Paper Question

1. The table below contains information about various components of the mammalian circulatory system.

blood inaorta

tissuefluid lymph blood in

vena cava

red blood cells many none many

white blood cells some some many

glucose concentration high high high

pressure high low low

(a) (i) Complete each of the shaded boxes in the table with the most appropriate word.

[4]

(ii) Explain the differences recorded in the table for glucose and pressure.

glucose ...................................................................................................

................................................................................................................

................................................................................................................

pressure .................................................................................................

................................................................................................................

................................................................................................................

[4]

Oxygen

24

Key Term Definition/Example/Diagram/FormulaHaemoglobin

Oxyhaemoglobin

Affinity

Partial Pressure

Dissociation

25

Past Paper Questions:

1. (a) Oxygen is carried around the bodies of mammals, bound reversibly to the pigment haemoglobin. The pigment is found in both adult and fetal red blood cells.

The graph below shows the dissociation curves for maternal and fetal oxyhaemoglobin.

0 2 4 6 80

20

40

60

80

100

par tia l p ressure of oxygen / kPa

satu ra tion o fhaem oglobin

w ith oxygen / %

feta l

m aterna l

10 12

(i) State the difference in the percentage saturation of haemoglobin with oxygen between the fetal and the maternal blood at an oxygen partial pressure of 3 kPa.

................................................................................................................

[1]

26

(ii) Explain why the difference between the two curves is essential for the survival of the fetus.

................................................................................................................

................................................................................................................

................................................................................................................

................................................................................................................

................................................................................................................

................................................................................................................

................................................................................................................

[4]

(b) After birth, the adult form of haemoglobin gradually replaces the fetal form of haemoglobin.

Suggest why this is necessary.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

[2]

2. The synthesis of red blood cells is stimulated by the hormone erythropoetin (EPO) which is secreted by the kidneys. Some long distance athletes have been known to take a course of EPO as part of a training programme.

Suggest why some athletes have taken erythropoetin.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

[Total 2 marks]

27

Carbon-dioxide

Key TermDefinition/Example/Diagram/Formula

Carbaminohaemoglobin

Chloride Shift

Dissociation Curve

Bohr Effect

How carbon dioxide is converted to hydrogencarbonate ions

28

The Bohr Effect

29

Past Paper Questions

1. Use the most appropriate terms to complete the paragraph below about the role of haemoglobin in the mammalian blood.

Haemoglobin, a pigment found in the blood of mammals, has an important role in the

transport of respiratory gases. Each haemoglobin molecule contains haem groups. In the

lungs, oxygen binds with the atom of ………………………… in each haem group. The

maximum number of molecules of oxygen that can be carried by one molecule of

haemoglobin is ………………………… . In areas like muscle tissue where the partial

pressure of oxygen is low, oxygen dissociates from the haem group. This dissociation is

increased by the presence of carbon dioxide; this is called the …………………………

………………………… . Most of the carbon dioxide produced in respiring tissues diffuses

into the red blood cells where the enzyme ………………………… ……………………

catalyses a reaction leading to the production of hydrogen ions and hydrogen carbonate

ions. The hydrogen ions combine very readily with haemoglobin to form a compound

known as ………………………… ………………………… . The effect of this is to increase

the release of oxygen from haemoglobin.

[Total 5 marks]

2. Fig. 1 shows the effect of two different partial pressures of carbon dioxide on the dissociation curve for haemoglobin.

30

100

80

60

40

20

00 1 2 3 4 5 6 7 8 9 10 11 12

partia l pressure of oxygen / kPa

% saturation ofhaem oglobinw ith oxygen

partia l pressure CO5.3 kP a

2

partia l pressure C O10.7 kP a

2

Fig. 1

(a) (i) Name the effect illustrated by the two curves.

................................................................................................................

[1]

(ii) The steepest part of each curve in Fig. 1 is between the oxygen partial pressures of 2 and 5 kPa.

Explain why it is important that this is so.

................................................................................................................

................................................................................................................

................................................................................................................

................................................................................................................

[2]

31

(iii) Explain how the effect of increasing the partial pressure of carbon dioxide from 5.3 to 10.7 kPa ensures a greater delivery of oxygen to exercising muscle tissue.

................................................................................................................

................................................................................................................

................................................................................................................

................................................................................................................

................................................................................................................

[2]

(b) The effect shown in Fig. 2 also increases the delivery of oxygen to exercising muscle tissue.

% saturation ofhaem oglob inw ith oxygen

100

80

60

40

20

0

tem perature 37ºC

partia l pressure of oxygen / kPa

0 2 4 6 8 10 12

tem perature 45ºC

Taken from 'Advanced Human Biology' by J. Simpkins and J.I. WilliamsFig 12.21, p233 (ISBN 0713527692)

Fig. 2

Suggest how exercising muscle tissue can bring about the changes seen inFig. 2.

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

.........................................................................................................................

[2]

32

33