1. A LEVEL BIOLOGY
8 TOPICS
12 REQUIRED PRACTICALS
3 EXAMS

4. Lesson Aims
How is the structure of the heart related to its function?
How much blood does the human body contain?
5.6 litres

5. The Heart Where is it? Between the two lungs Enclosed by the
PERICARDIUM
Pericardial fluid is secreted
between them to aid movement
The pericardium protects the
heart from over expansion
Where is it?

6. Internal Features Semi-lunar valves (bicuspid valve) Septum
Pericardial membranes

7. How far does your blood travel in one day?
Watch this Video
Blood flow through the heart
How far does your blood travel in one day?
nearly 12,000 miles

8. Blood flow through the heart
Blood comes into the heart from the body
It then has to pass to the lungs to collect oxygen
This is called a double circulatory system
After it returns to the heart it leave again to be transported to the body.
Task: Draw a flow diagram to show the flow of blood through the heart. You should start and finish with the body.

9. Atrium- receives blood from veins Ventricle- pumps blood into arteries
Body
Left
Vena cava
Oxygenated blood
Deoxygenated blood
atrium
Right
atrium
Bicuspid valve
Tricuspid valve
Pulmonary vein
Left ventricle
Right ventricle
aorta
Pulmonary artery
body
lungs

10. Drag the labels to the right place to complete the
Activity
Drag the labels to the right place to complete the
diagram and the key
A drag and drop activity

11. External Features

12. Your sheep’s heart What external features can you identify? A B C D
How much blood does the heart pump in a lifetime?
a million barrels of blood E F

13. External Features
FRONT
BACK
Apex

14. The Circulatory System

15. The Cardiac Cycle
Cardiac muscle contracts without nervous or hormonal stimulation these are MYOGENIC contractions.
The muscle cells work together to produce the heartbeat (cardiac cycle)

16. Semi-lunar valves closed
Systole (contraction)
Atrial systole
Atria contract
Semi-lunar valves closed
Blood forced from the atria into the ventricle
Ventricular systole
Ventricle contracts
Blood is forced into arteries
Bicuspid and tricuspid valves closed

17. Diastole (relaxation)
Heart relaxes and fills with blood from the veins.
Semi-lunar valves closed to blood entering through arteries.
Cardiac Cycle Tutorial
Task: Order the diagrams of the cardiac cycle and annotate.

18. HEARTRATE
What effects heart rate??

19. Control of the heart beat
Although the heart has its own rhythm it is also regulated by the nervous and hormonal systems.
Sensory receptors in the walls of heart and blood vessels are sensitive to changes in blood pressure
These send impulses to the CARDIORESPIRATORY CENTRE in the medulla oblongata
A vagus nerve branch leads to the SA node.
The vagus nerve is part of the Parasympathetic Nervous System and so is an inhibitory nerve, impulses slow the heart rate.