1. Breathing & Circulation

2. What do humans breathe through
What do humans breathe through? L_____________ What do fish use to breathe? G______________ Amphibians breathe through their s______________ Insects breathe through h__________ in their sides

3. Note:
Clear limewater goes milky in the presence of carbon dioxide

4. Breathing in and Breathing out Inhale – breathe in air Exhale – breathe out air

5. Structure of the Breathing System

6. The Breathing Mechanism

7. Exchange of Gas in the Alveoli Alveoli – small air sacs in the lungs There are between million alveoli in each human lung.

8. Each alveolus is surrounded by lots of tiny capillaries
Each alveolus is surrounded by lots of tiny capillaries. Oxygen diffuses (moves) into the blood from the alveolus and carbon dioxide diffuses from the blood to the alveolus through the very thin walls of the alveolus and capillaries

10. Breathing & Exercise Breathing allows us to obtain the oxygen we need for respiration Respiration – is the process in which our cells release energy from food. When we exercise our cells need more food. Therefore we need more food and oxygen. Our breathing and heart rate increase so that more oxygen can be carried by our blood to our cells and waste products i.e. carbon dioxide and water can be carried back to our lungs to breathe out.

13. Circulatory System William Harvey
While experimenting on veins he found that blood only flows in one direction around the body.
He also found that the same blood was being recirculated again and again through the heart.

14. Circulatory System

15. Adults have about 5 litres of blood flowing around their
body in tubes called blood
vessels.
Blood is made up of:
Plasma
Red blood cells
White blood cells
Platelets
Many substances are transported around your body in your blood e.g. gases, water and nutrients.

16. Plasma
The liquid part of the blood
90% water
Carries different cells
Many substances dissolve in it e.g. nutrients
Carries chemicals that stop us bleeding
Contains chemicals that help us fight off disease
Red Blood Cells
-Main job is to carry oxygen gas around the body
- They contain a red coloured protein called haemoglobin which contains iron
They pick up oxygen in the lungs
Red blood cells have no nucleus

17. White Blood Cells
Fight diseases
Attach and destroy invading micro-organisms
Patrol the bloodstream and tissues looking for germs
Some produce chemicals called antibodies that disable harmful invaders.
Platelets
Fragments of cells that help to clot the blood
Clotting is important because it helps to plug wounds
When blood vessels get damaged they send a signal to platelets to form a clot.

21. Circulation
We have two circuits
in our circulatory System
One loop goes to the lungs
from the heart
b) One loop goes to the
rest of the body from the
heart

22. One side of the heart pumps blood low in oxygen to the lungs
One side of the heart pumps blood low in oxygen to the lungs. In the lungs The blood collects oxygen and leaves behind carbon dioxide. This blood then returns to the heart. This oxygen rich blood is then pumped from the other side heart around the body to the cells. The cells need the oxygen for respiration.

23. The Human Heart

24. The Human Heart
About the size of your fist.
Acts as a pump
Made of muscle tissue – cardiac muscle
Pumps blood out into blood
vessels called arteries which carry
blood around the body.
-Blood is carried back to the heart
In blood vessels called veins
-Valves in the heart insure blood only
flows through the heart in one direction.

25. Blood Vessels
Three Types: Arteries, Veins & Capillaries
Veins – blood vessels that carry blood to
the heart.
Usually Carry blood low in oxygen
(deoxygenated blood).
Exception is the pulmonary vein
which carries blood rich in oxygen.

27. b. Arteries – blood vessels that carry blood away from the heart.
An exception is the pulmonary artery it
carries oxygen poor blood (blood rich
in carbon dioxide) from the heart to
the lungs.
c. Capillaries – Very narrow blood vessels that
allow for the exchange of water, gases nutrients
and waste between the blood and cells.
They have walls that are only one cell
thick for diffusion.

28. The pulse A pulse is a wave of pressure that travels along the walls of the arteries. Your heart rate is measured in beats per minute.

32. Dissection of a sheep’s heart