Download Heart Dissection Solutions

VCE Unit 1 Biology Heart Structure and Function
The Structure and Function of the Mammalian Heart
Name: ____________________
Date: ____________________
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Partner/s: ___________________________________
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Aim: To investigate the structure of a mammalian heart and determine the direction
of blood flow through it.
Material:
refer to prac. sheet The heart of the matter: Heart Structure and Function
Method:
Read the dissection instruction sheet carefully and answer the questions when you are directed to on the
prac. sheet.
Discussion Questions:
1. It is likely that the blood vessels that carry blood towards and away from the heart are missing from
your heart. If they are present examine them (the Aorta and pulmonary artery carrying blood from
the heart, and the vena cava and pulmonary vein carrying blood towards the heart. Compare the
size of their lumens (the space inside the vessel) and the thickness of their walls.
Aorta
Artery to right arm, head &neck
Superior Vena Cava
Pulmonary Artery
Right Atrium
Left Atrium
Right ventricle
Left Ventricle
Figure 1: The heart (Anterior View)
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VCE Unit 1 Biology Heart Structure and Function
Aorta
Pulmonary artery
Artery to right arm, head &neck
Superior vena cava
Pulmonary veins
Inferior vena cava
Right ventricle
Left ventricle
Figure 2: The heart (Posterior View)
The walls of the aorta and pulmonary artery are thicker and more elastic than the walls of the vena
cava and pulmonary veins. Suggest a reason for greater thickness and elasticity of the arteries
adjoining the heart.
Artery walls must be thicker than vein walls because artery walls need to be strong enough to
withstand the pressure from the blood forced into them from the ventricles (1)
on the other hand vein walls do not need to be thick as the blood they carry is at low pressure and
they don’t need to withstand an internal force like arteries do (1)
2. a) In which direction (from where and to where) would this valve (tricuspid) prevent blood from
flowing?
From the right ventricle( ½ ) back into the right atrium ( ½ )
(1)
b) Examine the Cordae Tendinae. These tendons(heart strings) attached the tricuspid valve to the
papillary muscle in the wall of the heart . How are they important to the proper functioning of this
valve?
When upward surging blood moves the valve cusps upwards the tendons stop them inverting or
prolapsing.(1)
Thus the valve snaps shut and this enables it to function properly to stop backflow of blood into
the atria(1).
3. In which direction (from where and to where) would these valves (semi lunar valves) prevent blood
from flowing?
From the pulmonary artery ( ½ ) back into the right ventricle( ½ ) (1)
4. In which direction (from where and to where) would these valves (semi lunar valves) prevent blood
from flowing?
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VCE Unit 1 Biology Heart Structure and Function
From the aorta( ½ ) back into the left ventricle( ½ ) (1)
5. (a) Where do these arteries (coronary arteries) lead?
They lead to the muscle tissue of the heart itself(1)
(b) These arteries (coronary arteries) receive blood that is just exiting the heart and at this point it is very
rich in oxygen. Why is it important for these particular arteries to receive blood containing a very high
concentration of oxygen? (Answer carefully including precise factual information making clear links
between the biological concepts included in your answer)
It is important for these arteries to contain a very high concentration of oxygen because:
A STATEMENT ABOUT THE HIGH METABOLIC ACTIVITY OF THE HEART
EG. The heart is a very active organ that is constantly beating; its muscle cells are continuously
contracting and relaxing and if this doesn’t happen (cells won’t have requirement supplied and
waste remove and) organisms will die
OR heart tissue is working hard ALL the time; even at rest is uses much more energy than leg
muscles during a sprint. (1)
OR similar
This work of the heart requires a lot of ATP(1) ( or if they just say energy (½ ))
Most ATP is supplied by aerobic respiration which requires oxygen as a reactants, thus high
oxygen supply is needed.(1)
6. (a) How do the thicknesses of the walls of the right atrium and right ventricle compare?
Right atrium wall is thinner than right ventricle wall
OR
right ventricle wall is thicker than right atrium wall
(b) Clearly explain these differences in terms of the different functions of the two types of
chambers.
Atria have thin muscular wall as only a small amount of force needs to be applied to move
blood a short distance into ventricles just below them. (1) Ventricles need to pump blood a
much greater distance (either to lungs or entire body) and so their walls are thicker to provide
the sufficient force to move blood to these destination.(1
7.
(a) How do the thicknesses of the right and left ventricle wall compare?
Right ventricle wall is thinner than left ventricle wall (1)
OR
Left ventricle wall is thicker than right ventricle wall (1)
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VCE Unit 1 Biology Heart Structure and Function
Blood leaves the ventricles of the heart and is carried to different destinations. Blood leaving from one
side of the heart is transported to the lungs and the blood leaving from the other side is transported to
various destinations around the whole body. Based on the observations made of the thickness of
the walls of these chambers, from which ventricle the right or the left do you think blood leaves to
circulate around the body? LEFT (no marks allocated to this answer)
Referring to the observations you have made during this practical investigation, clearly and fully explain
your choice
It was observed that the left ventricle wall was a lot thicker than the right ventricle wall. (1)
The thick wall of the left ventricle would provide more force than the thinner wall of the right
side of the heart (1)
Thus it would be able to move the blood the long distance needed to circulate the blood around
the whole body (1) compared to the shorted distance of the pulmonary circuit.
8. From the observations made in this activity, explain why the mammalian heart is described as a
double pump.
The heart is divided into two completely separate sides by a thick muscular wall or by the
septum.(1) Both sides simultaneously pump blood to different regions; one side pumps blood to
the lungs while at the same time the other side pumps blood to the rest of the body. Thus a double
pump(1)
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VCE Unit 1 Biology Heart Structure and Function
9..
 Label the simplified diagram of the heart below(2):
16-13 Correctly labelled (2), 12-10, (1½), 9-7(1), 6-4( ½ ) 3 or less (0)
 Use your observations of the valves to determine in which direction blood flows through the heart.
 Use blue arrows to show the movement of deoxygenated blood and red arrows to show the
movement of oxygenated blood. (1)
(1 mark)

Pulmonary artery
aorta
Aortic valve
Vena Cava
Pulmonary vein
Pulmonary
valve
Right atrium
Left atrium
septum
Tricuspid valve
Bicuspid valve
Tendon/heart string/
chordae tendineae
Tendon/heart string/
chordae tendineae
Right ventricle
Left ventricle
Apex
10. In the diagram of the heart above how can you tell, without ambiguity, which is the right side and which
is the left side?
By examining the thickness of the ventricle walls. The side with the thickest wall is the left, the side
with the thinner wall is the right.(1)
Write down 2 questions that you would like clarified in regards to the content covered so far about internal
transport.
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VCE Unit 1 Biology Heart Structure and Function
Applying Biological Understanding: Heart Structure and Function
A person is diagnosed with a hole in the heart. This means that there is a gap in the
septum between the two ventricles of the heart.
a) On the diagram below indicate with an X the region affected with a hole.(1)
b.
(i) Where does the right ventricle pump blood to? (1)
LUNGS
(ii) Where does the left ventricle pump blood to? (1)
AROUND THE REST OF THE BODY
c)
(i) How would the composition of the blood being pumped from
the left ventricle of a person with this condition compare with the
blood being pumped from the left ventricle of a normally function
IT WOULD CONTAIN LESS OXYGEN OR
IT WOULD CONTAIN MORE CARBON DIOXIDE
(ii) Explain the reason for this difference (2)
In healthy person the blood in the left ventricle is usually oxygen rich and the blood in the right
ventricle is usually oxygen poor and blood in each chamber is kept separate.(1)
If there is a hole in the septum oxygen poor blood(or blood rich in carbon dioxide) will enter the
left ventricle and mix with the blood in this chamber. This would result in the blood now having
less oxygen per(mL) (or more carbon dioxide per ml) than that of a normal person.(1)
(iii) Suggest and explain a possible symptom that a person with a hole in the heart might experience
due to this problem. (3)



Before to the mixing of blood, there was a decreased oxygen availability in the blood
Less oxygen for use in aerobic respiration(1/2) therefor Less ATP produced (1/2)
Therefor the person will feel tired./lacking in energy/lethargic(1)
An extra question
A person was born with a congenital heart defect; their Bicuspid valve was damaged and the two flaps
would not snap closed properly. Suggest a possible effect of this defect and explain your response.
This would result in backflow of blood from the left ventricle into the left atrium when the ventricle
wall contracts.
Which would mean less blood would be pumped from the left ventricle around the body with each
contraction.
This could result in less blood being transported to key tissues with each contraction. This could
result in a lack of energy as insufficient O2 for use in respiration to produce ATP
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