Respiration IGCSE

1. RESPIRATION B M Subramanya Swamy M.Sc. B.Ed. CIE Co ordinator & Examination Officer Kanaan Global School Jakarta Indonesia [email protected]

2. Introduction Energy is needed for cellular respiration Food is in the source of energy for human Oxygen is needed to release this energy from food Respiration is the process by which the body obtains and utilises oxygen and eliminates carbon dioxide

3. The three process of respiration in human Process Mode of action Breathing Involves external respiratory system to take in O 2 and release CO 2 Internal respiration Exchange of substances between capillaries and cells Cellular respiration Release of energy from food substances in living cells

4. CELLULAR RESPIRATION  the release of energy from food substances in all living cell Comparison of aerobic and anaerobic respiration Aerobic Anaerobic Oxygen Present Absent Energy from breakdown of food Large amount Relatively small Location Begins in cytoplasm and continues into the mitochondria In cytoplasm Efficiency Very good 36 molecules of ATP from 1 glucose molecule Inefficient 2 molecules of ATP from 1 glucose molecule Example of organism All organisms and some yeast Yeast, bacteria, seals and whales ( animals that dive deep into the ocean)

5. Aerobic Respiration C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + ENERGY Uses of aerobic respiration in human Uses of energy Mode of action Muscle contraction For muscular contractions, cardiac muscles and peristalsis Protein synthesis Formation of peptide bonds Cell division Growth, synthesis of chromosomes, cell membrane, etc. Active transport Transport of substances across a concentration gradient Growth New protoplasm, and in metabolic processes Transmission of nerve impulse Along the axon, and for the transport of sodium ions out Regulation of body temperature Energy released to keep the body warm

6. Anaerobic Respiration Anaerobic respiration and its uses Types Mode of action Alcoholic fermentation (in plants) Incomplete breakdown of sugar to release energy Glucose  ethanol + CO 2 + energy (2 ATP) Economically important, e.g. in bread making, brewing of beer and wine Lactic acid fermentation (in man and animal) Some bacteria causes milk to turn sour and form yoghurt The bacteria feeds on sugar Glucose  lactic acid + energy (2 ATP)

7. Anaerobic respiration and its uses Types Mode of action During rigorous muscular activity During strenuous activity, breathing is not enough to provide O 2 for respiration Muscles experience a shortage of O 2 , causing formation of lactic acid Accumulation of lactic acid causes muscular cramp and fatigue Muscle experiences O 2 debt during periods of anaerobic respiration Rapid breathing helps to repay the debt by increasing O 2 in the muscles, thus converting lactic acid back to glucose

8. GASEOUS EXCHANGE IN MAN Lungs are the main respiratory organ in human They lie in the upper chest cavity Lungs are divided into section called lobes Air enters through nostril, into nasal passages, pharynx, larynx, trachea, bronchi and bronchioles before entering the alveoli

9. Components of respiratory organs and its function Organs Function Nostrils Projecting nasal hairs filter out dust and debris Nasal cavity Divided by septum Lined with ciliated epithelium Blood vessels below epithelium warms the air Pharynx Both air and food passage Warms, moistens and filters air Glottis Guarded by epiglottis (elastic flap at entrance of trachea) Larynx Has vocal cord Trachea Cylindrical tube with rings of cartilage to provide support Layer of cilia and mucus – secreting cells Traps debris and sweeps it upwards towards the mouth Divided to form two bronchi

10. Components of respiratory organs and its functions Organs Function Lung Rich in blood supply, site of gaseous exchange Left lung has two lobes Right lung is bigger, with three lobes Bronchus Divided into smaller tubes called bronchioles Plural membrane Encloses each lung Diaphragm Muscular tissue attached to thoracic cavity Separates thoracic cavity from abdominal cavity Thoracic cavity changes volume to assist in breathing Bronchiole Connects directly to alveoli Widens and narrows during breathing Alveoli Air sacs with thin wall with a moist surface A network of blood capillaries covers the alveoli

11. Process of breathing inspiration expiration

12. Comparison of inspiration and expiration Inspiration Expiration External intercostal muscle contracts Increase in volume of thoracic cavity Ribs swing upwards and outwards Diaphragm contracts, flattens down An increase in thoracic cavity volume reduces air pressure in the cavity and lungs. Gases expand to fill the available space, creating a partial vacuum. This forces air into the lungs. Internal intercostal muscle contracts Reduction in volume of thoracic cavity Ribs swing downwards and inward Diaphragm is relaxed and elevated A reduction in the volume of thoracic cavity increases air pressure. This forces air out of the lungs to equalise the pressure of the lungs with the atmosphere.

13. 23- 14 Alveolar Pressure Changes

14. Comparison of composition inhaled and exhaled air Inhaled air Exhaled air Oxygen 21% 17% Carbon dioxide < 0.1% 4% Nitrogen 79% 79% Temperature Room temperature 37 °C Moisture Variable 100% Dust Variable Absent

15. Control of Breathing The respiratory center is located in the lower medulla oblongata The stimulus for the respiratory center is the presence of CO 2 When CO 2 level increases, breathing rate increases as well During anxiety or anger, the hormone adrenaline increases metabolic rate and breathing If the levels drop, it inactivates the respiratory center. This could lead to death.

16. Adaptations of alveoli and blood capillaries for exchange of gases Adaptation Mode of action Network of blood capillaries For transport of gases to and from alveoli Large surface area Allows for increased rate of diffusion Moist surface of alveoli Allows gases to dissolve before diffusion occurs Concentration gradient Increased rate of diffusion Distance between alveoli and blood capillaries Short distance increases rate of diffusion Wall of alveoli and blood capillaries One cell thick : faster diffusion

17. Internal Respiration This is the exchange of gases between blood and body tissues Carbon dioxide is carried as carbamino haemoglobin or bicarbonate ions Hb + CO 2  carbamino haemoglobin CO 2 + H 2 O  H 2 CO 3 H 2 CO 3  H + +HCO 3 -

18. Passage of Gases Oxygen Carbon dioxide During inspiration, O 2 diffuses across the alveolus During expiration, CO 2 is expelled with water vapour from the lungs It enters the blood stream There is a higher concentration of deoxygenated blood in this area 98% combines with blood to form oxyhaemoglobin It is carried in the blood as bicarbonate ions and carbamino haemoglobin < 2% enters the plasma It diffuses out of capillary into the alveoli

19. 23- 24 Pulmonary Volumes Tidal volume Volume of air inspired or expired during a normal inspiration or expiration Inspiratory reserve volume Amount of air inspired forcefully after inspiration of normal tidal volume Expiratory reserve volume Amount of air forcefully expired after expiration of normal tidal volume Residual volume Volume of air remaining in respiratory passages and lungs after the most forceful expiration

20. 23- 25 Pulmonary Capacities Inspiratory capacity Tidal volume plus inspiratory reserve volume Functional residual capacity Expiratory reserve volume plus the residual volume Vital capacity Sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume Total lung capacity Sum of inspiratory and expiratory reserve volumes plus the tidal volume and residual volume

21. 23- 26 Spirometer and Lung Volumes/Capacities

22. 23- 27 Respiratory System Functions Gas exchange : Oxygen enters blood and carbon dioxide leaves Regulation of blood pH : Altered by changing blood carbon dioxide levels Carbonic acid Buffer system Sound production : Movement of air past vocal folds makes sound and speech Olfaction : Smell occurs when airborne molecules drawn into nasal cavity Thermoregulation : Heating and cooling of body Protection : Against microorganisms by preventing entry and removing them