6.2.1 Draw and label a diagram of the heart showing the four chambers, associated blood vessels, valves and the route of blood through the heart.(1)











heart valves

Heart Valves




opn heart valve



Pressure of blood to the left is greater than pressure to the right

Valve flaps (cusps) pushed open.

Blood flows to the right.








The pressure on the right is greater than the pressure on the left.

Cusps pushed closed.

Back flow stops






6.2.2 State that the coronary arteries supply heart muscle with oxygen and nutrients.(1)













6.2.3 Explain the action of the heart in terms of collecting blood, pumping blood, and opening and closing of valves.(3)
























Late Diastole









Atrial systole








Ventricular Systole





6.2.4 Outline the control of the heartbeat in terms of myogenic muscle contraction, the role of the pacemaker, nerves, the medulla of the brain and epinephrine (adrenaline).(2)










The atria have already contracted sending blood down into the ventricles.

The ventricles are stretched and full of blood.

(A) The impulse to contract (generated in the SAN) is picked up by the AVN .

(B) The impulse to 'contract' travels down the septum of the heart, insulated from ventricle muscle fibres

(C) The impulse emerges first at the apex of the heart. This causes this region to contract first.

(D) The impulse now emerges higher up causing this region to contract.

(E). This region contract last.

The effect is to spread the contraction from the apex upwards, pushing blood towards the semi-lunar valves.





medulla heart rate


Modification of myogenic contraction

The basic myogenic contraction can be accelerated or slowed by nerve input form the brain stem or medulla.

There are two nerves:










Epinephrine (adrenaline) and heart rate








6.2.5 Explain the relationship between the structure and function of arteries, capillaries and veins.(3).


blood vesselsa) Arteries have muscular walls and outer layer of collagen for support.

The collagen resists the expansion due to the high pressure of blood.

The muscle layer contracts on the pulse of blood maintaining pressure all the way to the tissues.

b) Veins have carry blood under low pressure the lumen is wide to reduce the resistance to blood flow.



c) Capillaries have only a single layer of endothelium through which exchange can occur in the tissues.


blood networks

General functions of arteries and veins.

Arteries carry blood away form the heart under high pressure.

Veins return blood to the heart under lower pressure.

Capillaries are the site of exchange of blood with tissue fluid and cells.








6.2.6 State that blood is composed of plasma, erythrocytes, leucocytes (phagocytes and lymphocytes) and platelets.(1)






Plasma is largely water and makes up about 55% of the total blood volume.

This is the main transporting part of blood and takes advantage of the solvent properties of water.

The items listed to the left are shown for discussion only.








Blood cells


Erythrocytes are the red blood cells.

Leucocytes are the white blood cells

Relative numbers are shown for illustration purposes only.





















6.2.7 State that the following are transported by the blood: nutrients, oxygen, carbon dioxide, hormones, antibodies, urea and heat.(1)


The items listed above take advantage of the properties of water (as a solvent):

or its thermal properties:

Oxygen and carbon dioxide rely in the RBC for their transport:




Click4Biology: 6.2 Transport system

6.2.1 Structure of the heart.

6.2.2 Coronary arteries.

6.2.3 Cardiac cycle.

6.2.4 Control of heart rate

6.2.5 Structure and function of arteries, capillaries and veins.

6.2.6 Composition of blood

6.2.7 Transported substances.