1. Chapter 25
Respiratory System

2. Cells continually use O2 & release CO2
Respiratory system designed for gas exchange
Cardiovascular system transports gases in blood
Failure of either system
rapid cell death from O2 starvation

3. This will be a fill-in on the final

4. Respiratory System Anatomy
Nose
Pharynx = throat
Larynx = voicebox
Trachea = windpipe
Bronchi = airways
Lungs
Locations of infections
upper respiratory tract is above vocal cords
lower respiratory tract is below vocal cords

5. External Nasal Structures
Skin, nasal bones, & cartilage lined with mucous membrane
Openings called external nares or nostrils

6. Structure of the Nose Nose is divided into two regions:
External nose, including the root, bridge, dorsum nasi, and apex
Internal nasal cavity
Philtrum – a shallow vertical groove inferior to the apex
The external nares (nostrils) are bounded laterally by the alae

7. Nose -- Internal Structures
Large chamber within the skull
Roof is made up of ethmoid and floor is hard palate
Internal nares are openings to pharynx
Nasal septum is composed of bone & cartilage
Bony swelling or conchae on lateral walls

8. Functions of the Nasal Structures
Olfactory epithelium for sense of smell
Pseudostratified ciliated columnar with goblet cells lines nasal cavity
warms air due to high vascularity
mucous moistens air & traps dust
cilia move mucous towards pharynx

9. Pharynx Extends from internal nares to cricoid cartilage Functions
passageway for food and air
resonating chamber for speech production
Distinct regions -- nasopharynx, oropharynx and laryngopharynx

10. Cartilages of the Larynx
Thyroid cartilage forms Adam’s apple
Epiglottis---leaf-shaped piece of elastic cartilage
during swallowing, larynx moves upward
epiglottis bends to cover glottis
Cricoid cartilage---ring of cartilage attached to top of trachea

11. Framework of the Larynx

12. The Structures of Voice Production
True vocal cord contains both skeletal muscle and an elastic ligament (vocal ligament)
When 10 intrinsic muscles of the larynx contract, move cartilages & stretch vocal cord tight
When air is pushed past tight ligament, sound is produced (the longer & thicker vocal cord in male produces a lower pitch of sound)
The tighter the ligament, the higher the pitch
To increase volume of sound, push air harder

13. Trachea Size is 5 in long & 1in diameter
Extends from larynx to primary bronchi near lungs
Layers
mucosa = pseudostratified columnar with cilia & goblet
submucosa = loose connective tissue & seromucous glands
hyaline cartilage = 16 to 20 incomplete rings

14. Trachea and Bronchial Tree
Full extent of airways is visible starting at the larynx and trachea (fill in for final)

15. Airway Epithelium
Ciliated pseudostratified columnar epithelium with goblet cells produce a moving mass of mucus.

16. Histology of Bronchial Tree
Epithelium changes from pseudostratified ciliated columnar to nonciliated simple cuboidal as pass deeper into lungs
Incomplete rings of cartilage replaced by rings of smooth muscle & then connective tissue
adrenal gland releases epinephrine that relaxes smooth muscle & dilates airways
asthma attack or allergic reactions constrict distal bronchiole smooth muscle
nebulization therapy = inhale mist with chemicals that relax muscle & reduce thickness of mucus

17. Pleural Membranes & Pleural Cavity
Visceral pleura covers lungs --- parietal pleura lines ribcage & covers upper surface of diaphragm
Pleural cavity is potential space between ribs & lungs

18. Structures within a Lobule of Lung
Branchings of single arteriole, venule & bronchiole are wrapped by elastic CT
Respiratory bronchiole
Alveolar ducts surrounded by alveolar sacs & alveoli
Site of gas exchange

19. Histology of Lung Tissue

20. Breathing or Pulmonary Ventilation
Air moves into lungs when pressure inside lungs is less than atmospheric pressure
How is this accomplished?
Air moves out of the lungs when pressure inside lungs is greater than atmospheric pressure
Atmospheric pressure = 1 atm or 760mm Hg

21. Dimensions of the Chest Cavity
Breathing in requires muscular activity & chest size changes
Contraction of the diaphragm flattens the dome and increases the vertical dimension of the chest

22. Quiet Inspiration Diaphragm moves 1 cm & ribs lifted by muscles
Intrathoracic pressure falls and 2-3 liters inhaled

23. Quiet Expiration Passive process with no muscle action
Elastic recoil & surface tension in alveoli pulls inward
Alveolar pressure increases & air is pushed out

24. Labored Breathing Forced expiration Forced inspiration
abdominal mm force diaphragm up
internal intercostals depress ribs
Forced inspiration
sternocleidomastoid, scalenes & pectoralis minor lift chest upwards as you gasp for air

25. Summary of Breathing Alveolar pressure decreases & air rushes in
Alveolar pressure increases & air rushes out

26. Alveolar Surface Tension
Thin layer of fluid in alveoli causes inwardly directed force = surface tension
water molecules strongly attracted to each other
Causes alveoli to remain as small as possible
Detergent-like substance called surfactant
lowers alveolar surface tension

27. Pneumothorax
Pleural cavities are sealed cavities not open to the outside
Injuries to the chest wall that let air enter the intrapleural space
causes a pneumothorax
collapsed lung on same side as injury
surface tension and recoil of elastic fibers causes the lung to collapse