1. Organs of the Respiratory system
Nose
Pharynx
Larynx
Trachea
Bronchi
Lungs – alveoli
Figure 13.1

2. Function of the Respiratory System
Purify, warm, and humidify incoming air
Gas exchange – alveoli
Air enters through external nares (nostrils)
The interior of the nose consists of a nasal cavity divided by a nasal septum

3. Upper Respiratory Tract
Figure 13.2

4. Anatomy of the Nasal Cavity
Olfactory receptors on the superior surface
Cavity is lined with respiratory mucosa
Moistens/humidifies air
Traps incoming foreign particles
Lateral walls have conchae
Increase surface area & air turbulence
The nasal cavity is separated from the oral cavity by the hard (ant.) and soft (post.) palate

5. Paranasal Sinuses

6. Paranasal Sinuses
Cavities within bones surrounding the nasal cavity
Lighten skull
Resonance chambers for speech
Produce mucus - drains into the nasal cavity
Neti pot video

7. Larynx
Routes air and food into proper channels
Plays a role in speech
Made of eight rigid hyaline cartilages and a flap of elastic cartilage (epiglottis)

8. Structures of the Larynx
Thyroid cartilage
Protrudes anteriorly (Adam’s apple)
Vocal cords (vocal folds)
Vibrate with expelled air to create sound
Vid 1 Vid 2
Thyroid cartilage
Protrudes anteriorly (Adam’s apple)
Vocal cords (vocal folds)
Vibrate with expelled air to create sound
Vid 1 Vid 2

9. Trachea (Windpipe) Connects larynx with bronchi
Lined with ciliated cells
Beat continuously in the opposite direction of incoming air
Expel mucus loaded with dust and other debris away from lungs
Walls are reinforced with C-shaped hyaline cartilage

10. Trachea (Windpipe)

11. Primary Bronchi
Bronchi subdivide into smaller and smaller branches
1o (primary) bronchi
2o (secondary) bronchi
3o (tertiary) bronchi
Bronchioles
Terminal bronchioles

12. Respiratory Tree Divisions

13. Bronchioles Smallest branches Terminal bronchioles end in alveoli
Structure of alveoli
Alveolar sac
Alveolar duct
Alveolus
Gas exchange takes place within the alveolus

14. Simple squamous epithelium lines alveolar walls
Alveoli
Simple squamous epithelium lines alveolar walls
Pulmonary capillaries cover external surfaces of alveoli

15. Respiratory Membrane (Air-Blood Barrier)
Figure 13.6

16. Gas Exchange
Gas diffuses across the respiratory membrane
O2 enters the blood (from alveoli)
CO2 enters the alveoli (from blood)
Macrophages in alveoli provide protection

17. Mechanics of Breathing
Completely mechanical process
Depends on volume changes in the thoracic cavity
Volume changes lead to pressure changes, which lead to the flow of gases to equalize pressure
Two phases
Inspiration – flow of air into lung
Expiration – air leaving lung

18. Inspiration
Diaphragm and intercostal muscles contract
The size of the thoracic cavity increases
External air is pulled into the lungs due to an increase in intrapulmonary volume (negative pressure)

19. Inspiration
Figure 13.7a

20. Expiration
Largely a passive process
Depends on natural lung elasticity
As muscles relax, air is pushed out of the lungs
Forced expiration can occur mostly by contracting internal intercostal muscles to depress the rib cage (positive pressure)

21. Expiration
Figure 13.7b

22. Respiratory Volumes and Capacities
Tidal volume (TV): Normal breathing moves about 500 ml of air with each breath
Factors that affect respiratory capacity
A person’s size, sex & age
Physical condition
Residual volume (RV): after exhalation, about 1200 ml of air remains in the lungs

23. Respiratory Capacities
Figure 13.9

24. Respiratory Volumes and Capacities
Inspiratory reserve volume (IRV)
Amount of air that can be taken in forcibly over the tidal volume
Usually between 2100 and 3200 ml
Expiratory reserve volume (ERV)
Amount of air that can be forcibly exhaled
Approximately 1200 ml

25. Respiratory Capacities
Figure 13.9

26. Respiratory Volumes and Capacities
Residual volume
Air remaining in lung after expiration
About 1200 ml

27. Respiratory Capacities
Figure 13.9

28. Respiratory Volumes and Capacities
Vital capacity
The total amount of exchangeable air
Vital capacity = TV + IRV + ERV
Dead space volume (Residual)
Air that remains in conducting zone and never reaches alveoli

29. Respiratory Volumes and Capacities
Functional volume
Air that actually reaches the respiratory zone
Respiratory capacities are measured with a spirometer

30. Respiratory Capacities
Figure 13.9

31. External and Internal Respiration
External Respiration
Internal Respiration
LUNGS
TISSUE
Bloodstream (capillaries)
Figure 13.11

32. External Respiration (betw. lungs & blood)
Oxygen movement into the blood
The alveoli always has more oxygen than the blood
Oxygen moves by diffusion towards the area of lower concentration of oxygen
Pulmonary (lung) capillary blood gains oxygen

33. External Respiration (betw. lungs & blood)
Carbon dioxide movement out of the blood
Blood returning from tissues has higher concentrations of carbon dioxide than air in the alveoli
Pulmonary capillary blood gives up carbon dioxide (diffusion)
Blood leaving the lungs is oxygen-rich and carbon dioxide-poor

34. Gas Transport in the Blood
Oxygen (O2) transport in the blood
Inside red blood cells attached to hemoglobin (oxy-hemoglobin)
A small amount is carried dissolved in the plasma
Carbon dioxide (CO2) transport in the blood
Most is transported in the plasma
A small amount is carried inside red blood cells on hemoglobin (but at different binding sites than those of oxygen)

35. Internal Respiration (betw. blood & tissue)
Exchange of gases between blood and body cells
The opposite of what occurs in the lungs
Carbon dioxide diffuses out of tissue to blood
Oxygen diffuses from blood into tissue

36. External and Internal Respiration
External Respiration
Internal Respiration
LUNGS
TISSUE
Bloodstream (capillaries)
Figure 13.11

37. Neural Regulation of Respiration
respiratory muscles
phrenic nerve diaphragm
intercostal nerves  intercostal muscles
Control center -- rate & depth – in medulla
Normal rate is 12–15 breaths/min.

38. Factors Influencing Respiratory Rate and Depth
Physical factors
Increased body temperature
Exercise, Talking, Coughing
Volition (conscious control)
Emotional factors
Carbon dioxide levels
Oxygen levels