1. Respiratory system

2. Learning objectives Why do we breathe? Why do we need oxygen? What are lungs? How do their structure affect the ability to absorb oxygen from air? How do we breathe? How does gas exchange occur between the air and our blood, and then between our blood and tissues? How does the brain regulate breathing? What are bronchitis, emphysema, asthma, and apnea?

3. Structure of the Respiratory System

4. Cilia and mucus-secreting cells line the bronchi

6. Respiration Overall exchange of oxygen from air for carbon dioxide (waste product)

7. Respiratory Cycle Volume of chest cavity increases & decreases,pressuregradientsaffected Inspiration Expiration

8. Breathing

9. How much air is in a breath? Tidal volume = amount of air in normal breath Vital capacity = maximum amount of air that can move out of lungs after deep breath

10. PhasesofRespiration

11. Gas exchange depends on pressure gradients O 2 and CO 2 move from higher concentration (pressure) to lower concentration (pressure)

12. Hemoglobin binds to oxygen & carries it to tissues Helps to maintain pressure gradient at respiratory surface

13. Alveoli are ideal for gas exchange Alveoli+capillary = THIN respiratory membrane sac capillary alveolar pulmonary

16. Oxygen forms weak bonds with hemoglobin = oxyhemoglobin Hemoglobin transports oxygen to tissues CO 2 carried to lungs for exhalation

17. Respiratory“Pacemaker” Respiratory center in brain stem stimulates rib cage muscles and diaphragm to contract

18. Chemoreceptors in arteries monitor brain stem and CO2CO2 andpH If blood is too acidic, breathing becomes deeper and more frequent

19. Breathing patterns change with a person’s activity level

20. Bronchitis Inflammation of bronchi brought on by pollution, smoke Mucus accumulates and traps particles (including bacteria) Bacteria attack bronchi, scar tissue may form

21. Emphysema Alveoli break down and are surrounded by scar tissue Loss of elasticity in lung tissue Gases not exchanged efficiently

22. Asthma Sudden narrowing of bronchioles caused by spasms of muscle in walls Mucus also rushes in Breathing becomes instantly difficult

23. Apnea Breathing stops briefly, then resumes spontaneously May happen frequently during sleep Age, weight contribute to apnea