1. The Respiratory System
A Breathtaking Analysis of Structure and Function

2. Nose External nares = nostrils Vestibule – small hair-lined chamber
Nasal cavity
Divided by nasal septum
Lined with nasal conchae to increase surface area
** Ciliated mucous membrane

4. Pharynx Nasopharynx – behind nose; air only
Segments
Nasopharynx – behind nose; air only
Oropharynx – behind mouth; air & food
Laryngopharynx – air & food

6. Larnyx AKA Voice Box Thyroid & cricoid cartilage
Epiglottis – flap of tissue that closes over trachea when swallowing
Vocal cords – elastic tissue
UNCILIATED

9. WHY DO WE CLEAR OUR THROATS?

10. Trachea C rings of cartilage allow esophagus to expand
Lined with ciliated mucous membrane

11. Bronchial Tree R & L primary bronchi Branching network
Smallest tubes = Bronchioles
Connect to alveoli
Lined with surfactant to counteract surface tension of water

14. Lungs
Spongy organs containing bronchial tree & alveoli

15. Diaphragm
Separates thoracic cavity from abdominal cavity

16. Respiration Pulmonary ventilation – air in and out
External respiration – gases between lungs & blood
Internal respiration – gases between blood & body cells

17. Mechanics of Breathing

18. Background Information
Pressure is basically the number of collisions between molecules
Increasing the volume will…
Decreasing the volume will…

19. Inspiration (Inhalation)
Contraction of diaphragm & intercostals
Thoracic cavity expands, increasing the volume
Thoracic cavity pressure decreases

20. Inspiration (Inhalation)
Lung surface pulls outward, increasing the lung volume
Alveoli volume increases & pressure drops
Air rushes in to restore equilibrium

21. Expiration (Exhalation)
Diaphragm & intercostals relax
Thoracic cavity reduces in size, increasing pressure
Lung surface recoils to original shape, increasing pressure

22. Expiration (Exhalation)
Volume of alveoli decreases
Alveolar pressure increases
Air flows out of alveoli

23. ASTHMA Tightening of bronchial tubes from spasms & mucus
Chronic vs. exercise-induced vs. occupational
Vary based on trigger/cause

25. Exchange of Gases

26. Basic Information
Partial pressures determine direction of movement of gases
Only gases in the plasma affect the partial pressure
Oxygen & CO2 diffuse independently of each other

27. External Respiration Between alveoli & bloodstream
PO2 in alveoli > PO2 in plasma
Most O2 entering blood is bound by Hb
O2 goes to plasma only when Hb is saturated

28. External Respiration CO2 in opposite direction
PCO2 in plasma > PCO2 in alveoli

30. Internal Respiration Between capillaries & body cells
PO2 in capillaries > cytoplasm
PCO2 in cytoplasm > capillaries

31. But there’s a catch… CO2 has an affinity for Hb
If CO2 binds to Hb, it blocks the binding sites for O2
If O2 can’t bind to Hb, we can’t bring nearly as much O2 into the blood

32. So…
When CO2 enters the blood, it combines with water to form carbonic acid
The carbonic acid immediately breaks down into Hydrogen ions (H+) & Bicarbonate ions (HCO3-)

33. Then…
The H+ can’t be left in the plasma so it hitches a ride on the Hb
The HCO3- just chills in the plasma and makes the trip to the lungs

34. In the lungs…
H+ & HCO3- recombine to form carbonic acid and then CO2 & H2O
The CO2 is exhaled and the H2O stays in the body

35. The formula…
CO2 + H2O  H2CO3  H+ + HCO3-