1. Respiratory system 1
Physiology
232 BMS

2. Objectives
Define the four processes which are included under respiration
List the functions of each part of respiratory system (Nose – Pharynx – Larynx – Trachea)
Explain blood supply to lungs
Explain the mechanics of breathing & respiratory pressures

3. Respiratory system
The major function of respiratory system is to supply the body with oxygen & dispose carbon dioxide out of the body.
For this function to occur, four processes must occur, which collectively are called (Respiration):

4. Pulmonary ventilation
External respiration
Internal respiration
Transport of respiratory gases

5. Respiratory system Pulmonary ventilation:
Movement of air into & out of the lungs, so that the gases are continuously changed & refreshed (Called: Breathing)

6. Respiratory system External respiration:
Movement of oxygen from lungs to the blood & carbon dioxide from blood to the lungs

7. Respiratory system Internal respiration:
Movement of oxygen from blood to the tissues & carbon dioxide from tissues to the blood

8. Respiratory system Transport of respiratory gases:
Transport of oxygen from lungs to tissues & carbon dioxide from tissues to lungs

9. Respiratory system Respiratory system includes: Nose – Nasal cavity
Pharynx – Larynx
Trachea – Two bronchi
Bronchioles & smaller air passages
Lungs which contain the air sacs (Alveoli)

10. Respiratory system Nose
Is the only external visible part of the respiratory system

11. Functions: (Nose) Provides an airway for respiration
Moistens & warms the entering air
Filters & cleans the entering air (Hairs present will trap large particles, & smaller particles as dust will adhere o the mucus)
Contain the (Smell) receptors

12. Nose contains
Mucous glands
Serous glands

13. Mucous glands: Serous glands:
Secretes mucus which traps inspired dust & bacteria – Protects the underlying tissue from irritation - & Prevents drying
Serous glands:
Secretes watery fluid containing enzymes that attack & destroy the bacteria

14. Pharynx
It connects the nasal cavity & mouth superiorly to the larynx & inferiorly to the esophagus
Pharynx is divided into three regions: Nasopharynx – Oropharynx –Laryngopharynx

16. Pharynx
Nasopharynx: Because it lies above the point where food enters the body, it serves only as passage for air
Oropharynx: Serves as a passage for air & ingested food
Laryngopharynx: Serves as a passage for air & ingested food

17. Functions of pharynx: Acts as a pathway for air & food
Warming & humidifying of air before it enters to lungs
Important in tasting
Protection: It produces antibodies against microbes
Important in speech, as it acts as a chamber for the sound ascending from the larynx, & helps to give the voice its individual characteristics

18. Larynx (Voice box) It lies between pharynx & trachea Functions:
Acts as a passage for air (Between pharynx & trachea)
Warming & humidifying the air
Voice production (As it contains the vocal cords)
It lies between pharynx & trachea

19. Larynx (Voice box)
There is a flap that closes over the larynx during swallowing to prevent the food from entering the larynx & trachea, & force the food to go to the esophagus
( During swallowing, the larynx is pulled superiorly, & epiglottis covers the laryngeal opening)
Anything other than air entering the larynx will initiate the cough reflex, which acts to expel the substance

20. Trachea Functions: Warming & humidifying the air
It descends from the larynx through the neck
Functions:
Warming & humidifying the air
Cough reflex (Nerve endings in larynx & trachea are sensitive to any substance that enters other than the air)

21. Trachea (Windpipe)

22. Bronchi – Bronchioles & Alveoli
Trachea is divided into right & left bronchi (Primary bronchi)
(The right main bronchus is wider, shorter & more vertical than the left)
Once inside the lung, each main bronchus is divided into secondary (Lobar) bronchi (Three on the right & two on the left)
Then secondary bronchi divide into tertiary (Segmental) bronchi & then into smaller bronchi (Bronchioles)

23. Bronchi – Bronchioles & Alveoli

24. Alveoli The alveoli have three characteristic features:
At the end of bronchioles, there are air sacs called (Alveoli)
The alveoli have three characteristic features:
They are surrounded by fine elastic fibers of the same type that surround the entire bronchial tree

25. Alveoli
There are alveolar pores connecting the adjacent alveoli to provide an alternate pathway to any alveoli whose bronchi have collapsed due to a disease
There are alveolar macrophages which are moving freely along the internal alveolar surfaces

26. The lungs are perfused by two circulations:
Blood supply to lungs
The lungs are perfused by two circulations:
Pulmonary circulation
Bronchial circulation

27. Pulmonary circulation:
Blood supply to lungs
Pulmonary circulation:
Deoxygenated blood passes from the heart to enter the lungs through the Pulmonary arteries
The blood becomes oxygenated inside the lungs, & goes to enter the heart through the Pulmonary veins

28. Bronchial circulation:
Blood supply to lungs
Bronchial circulation:
Bronchial arteries which provide systemic blood to the lung tissue, arise from the aorta, & enters the lungs supplying all lung tissue (Except: Alveoli, it is supplied by Pulmonary circulation)

29. Pleura & pleural cavity
It consists of a closed sac around each lung
It consists of two layers, one adheres to the lungs & the other to the wall of the thoracic cavity

30. Pleura & pleural cavity
Visceral pleura: This is adherent to the lungs, covering each lobe & passing into the fissures which separate them Parietal pleura: This is adherent to the wall of the thoracic cavity Pleural cavity: Is a space between the two pleura, containing serous fluid which allows them to glide over each other, preventing friction between them during breathing

32. Mechanics of breathing
Breathing consists of two phases:
Inspiration ….. The period when air flows into the lungs
Expiration ….. The period when gases exit the lungs

33. Mechanics of breathing
Respiratory pressures: It is always described relative to atmospheric pressure (Patm ) … Which is the pressure exerted by gases surrounding the body At sea level, Patm = 760mmHg = 1 atm.

34. Mechanics of breathing
Respiratory pressures:
A negative respiratory pressure in any area (As: - 4mmHg) indicates that the pressure in this area is lower than the atmospheric pressure by 4 mmHg
A positive respiratory pressure in any area indicates that the pressure in this area is higher than the atmospheric pressure
Zero respiratory pressure indicates that the pressure in this area equals to the atmospheric pressure

35. Mechanics of breathing
Respiratory pressures:
Intrapulmonary pressure (Ppul ): Is the pressure inside the alveoli
It increases & decreases according to the phases of breathing
Intrapleural pressure (Pip ): Is the pressure in the pleural cavity

36. Inspiration & Expiration