1. Gas Exchange (Core)

2. 6.4.1 Distinguish between ventilation, gas exchange and cell respiration

3. Breathing is NOT respiration! Ventilation Movement of air into and out of the lungs in two stages: inspiration & expiration. Controlled by diaphragm & ribcage. Gas Exchange The exchange (diffusion) of oxygen and carbon dioxide to and from the blood at the alveoli and the respiring tissues Cell Respiration This is production of ATP at the cellular level (mitochondri a). Aerobic respiration uses oxygen, whereas anaerobic does not.

4. Ventilation Movement of gases – 1 st, in the lungs where oxygen moves from the air into the bloodstream – 2 nd, in a capillary bed elsewhere in the body where the opposite gas exchange occurs, (O 2 & CO 2 )

5. 6.4.2 Explain the need for a ventilation system

6. Why do we need a ventilation system? We are large organisms. Oxygen cannot diffuse into all our cells directly from the air, nor can waste products be directly ejected from the body. The ventilation system ensures the blood can be the medium for this.

7. Why a ventilation system? We are land-borne. Gases need moist surfaces in order to diffuse Lungs are moist membranes Vent. System maintains a large concentration gradients The constant flow of blood past the alveoli brings blood with a high CO 2 concentration and low O 2 concentration Exhaling keeps the CO 2 concentration in the alveoli low, so it diffuses out.

8. Ventilation System High concentration gradients must be maintained in the alveoli. Breathing in increases the concentration gradient of oxygen between the alveoli & blood (diffuse in) Breathing out removes (CO 2 ) increasing the concentration gradient of CO 2 between blood and alveolus – CO 2 diffuses out

9. Gas Exchange If the alveoli were not ventilated, equilibrium would be reached and no gas could be exchanged.

10. Respiratory Basics

11. 6.4.3 Describe the features of alveoli that adapt them to gas exchange

12. Alveoli are well adapted to gas exchange Alveoli increase the surface area for gas exchange. Millions in number, each with their own network of capillaries Rich blood supply maintains a high concentration gradient of O 2 and CO 2 Surfaces are wet

13. Alveoli Membranes are very thin – Both of the alveoli and the capillaries Diffusion path is short

14. Which process(es) of membrane transport are being used in gas exchange at the membranes of the alveoli?

15. How many membranes must an oxygen molecule pass through in order to enter an erythrocyte?

16. 6.4.4 Draw and label a diagram of the ventilation system, including trachea, lungs, bronchi, bronchioles and alveoli.

18. 6.4.5 Explain the mechanism of ventilation of the lungs in terms of volume and pressure changes caused by the internal and external intercostal muscles, the diaphragm and abdominal muscles.

19. Gas Exchange

20. Gas exchange

22. Mechanisms of inspiration 1.The diaphragm contracts & at the same time the abdominal muscles and intercostal muscles help to raise the rib cage. All of these help increase the volume of the thoracic cavity. 2.Because of the increase in volume, the pressure inside the cavity decreases. Leads to less pressure “pushing on” the passive lung tissue

23. Mechanism of inspiration 3)The lung tissue increases its volume because there is less pressure exerted on it. 4)This leads to a decrease in pressure inside of the lungs, also known as a partial vacuum 5)Air comes in through your open mouth or nasal passages to counter the partial vacuum within the lungs

24. Mechanism of Expiration Previous steps reversed.