Respiration in Humans (part 2): Gaseous exchange & lung capacity

1. ? ? ? ? ? ? ? ? ? ? ? Qn: Does respiration equate to breathing? respiration = breathing??? ? ? ? ? ? ? ? ? ? ? ? ?

2. Tissue respiration, Gas exchange and Breathing Aerobic respiration involves both Internal respiration (tissue respiration) - oxidation of organic food molecules with the liberation of energy; occurs in cells/tissues of living organisms External respiration (gaseous exchange) - process of O2transfer from surrounding air/water to cells and the transfer of products of respiration (CO2+H2O) from cells to surrounding medium (air/water) - Breathing part of gaseous exchange; muscular contractions and movement of ribs resulting in the movement of air in and out of lungs

3. Internal respiration in living cells Glucose + oxygen carbon dioxide + water + energy oxygen glucose living cell energy nucleus carbon dioxide water

4. Respiration and breathing Respiration Breathing Takes place in every living cell A process that involves the release of energy from food Takes place in the lungs A process of gaseous exchange – taking air in and out of the body Removes the carbon dioxide produced during respiration Uses the oxygen absorbed during breathing

5. Gaseous exchange in animals large animals unicellular aquatic organisms small surface: volume ratio large surface area: volume ratio protection prevent H2O loss thickened external surface efficient diffusion possess special organs; gills/lungs + breathing movements Do not require special gas exchange/O2transport mechanisms gas exchange surface enlarged; thin covering efficient diffusion

6. Gas exchange system in Man [pg.202 textbk] nasal passages (thin layer of lubricating fluid) (antagonistic) (air sacs) (dome-shaped sheet of muscle + elastic tissue)

7. Identify the following components: 1. 2. 3. 4. 5. 8. 6. 9. 10. 7. 11. 12.

8. Structure of trachea [pg.203 textbook]Epithelium lining of trachea and bronchi (traps dust particles and bacteria) (ensures that nasal passages are always open) (helps to sweep particles up the bronchi + trachea → pharynx → oesophagus)

9. Activity: Place your hand on your chest. Breathe in and out. What do you observe?

10. Breathing (rib cage movement) (breathing in) (breathing out)

11. What happens during breathing? (external intercostal muscles relax; internal intercostal muscles contracts) (external intercostal muscles contract; internal intercostal muscles relax) (thoracic cavity increases) (thoracic cavity decreases) (flattens downwards) (arches upwards) Boyle’s law: p V = constant When volume increases, pressure decreases When volume decreases, pressure increases

12. Gas exchange system in Man [pg.202 textbk] nasal passages (thin layer of lubricating fluid) (antagonistic) (air sacs) (dome-shaped sheet of muscle + elastic tissue)

13. Gaseous exchange in lungs High [O2] low [O2] Establish diffusion gradient

14. Gas Exchange Between Alveoli and Capillaries

15. What are the adaptations of the alveoli to its function? alveolar wall (one celled thick) air movement thin film of moisture alveolar cavity High [O2] blood capillary RBC low [O2] Establish diffusion gradient

16. Formation of oxyhaemoglobin

17. Oxyhaemoglobin reversible How do we know the direction of association/dissociation? High [O2](lungs) Low [O2] (O2-poor tissues)

18. Transport of CO2 [refer to pg.209 textbook] CO2is carried in blood in 3 different ways 1. Most of it (about 80%–90%) transported in the plasma as hydrogencarbonate ions (HCO3-) 2. 5%–10% is dissolved in the plasma 3. 5%–10% is bound to haemoglobin as carbamino compounds •

19. Transport of CO2

20. Transport of CO2 carbonic anhydrase ↔ CO2+ H2O H2CO3 HCO3-+ H+ ↔ hydrogencarbonate ion + hydrogen ion carbonic acid carbon dioxide + water

21. Summary

22. Composition of inspired and expired air Aerobic respiration in living cells glucose + oxygen → carbon dioxide + water + energy

23. 10.6 To compare the amount of CO2in inspired and expired air [pg.210 textbk] Inspired air (slightly white ppt.) Expired air (white ppt.)

24. 10.7 To compare the amount of O2 in inspired air and expired air downward displacement of water Collection of expired air downward displacement of water oxidation of yellow phosphorus upward displacement of water reflects volume of O2present

25. 10.7 To compare the amount of O2 in inspired air and expired air Calculations: Volume of expired air at beginning of experiment = a cm3 Volume of expired air at end of experiment = b cm3 Volume of oxygen absorbed = (a – b) cm3 Percentage of O2in expired air = (a – b)/a x 100% Note: Repeat experiment using inspired air (atmospheric air)

26. Activity for lung capacity

27. Lung capacities (extra volume of air that is taken in when taking a deep breath) (max. volume of air that can be taken in/ breathed out) (same volume of air that enter or exits in a normal breathing cycle; varies for diff. individuals) (extra volume of air that can be forced out by expiration) (residual volume of air after expiration)

28. **Stimulus for breathing ▪ Is the high conc. of CO2in the blood/alveolar air ▪ And not a lack of O2 ▪ No breathing movements occur when low CO2in lungs Irritant particles ▪ Filtered by nose hair/trapped in mucus ▪ If enter respiratory passages → automatic violent coughing (expulsion)/ sneezing to expel them ▪ Occupational hazard (wear protective masks, if not can give rise to lung damage)