1. Respiratory System
Chapter 21 – Day 2
3/17/08

2. Pathway of Air/ O2
Nose – external nares → nasal cavity → internal nares 
Pharynx – nasopharynx → oropharynx → laryngopharynx
Larynx – epiglottis → larynx
Trachea – trachea
Bronchi – primary bronchi → secondary bronchi → tertiary bronchi → bronchioles
Lungs – alveoli → blood stream
3/17/08

3. Pathway of Air/ O2
Each component is composed of special tissues which aid in their function
Passageways & accessory structures in the nose and pharynx = upper respiratory system
Nose: external & internal nose
Outside: cartilage & skin structure with 2 openings = external nares
Directs air into nasal passageways
External = object of “vanity’
“nose job” = Rhinoplasty – surgery to repair or alter nose structure – involves addition or removal of tissue
Involves inconspicuous incisions & local anesthesia
3/17/08

4. Pathway of Air/ O2 - Skull
Nostrils lead into 2 chambers separated by the nasal septum
Right and left chambers of the nasal cavity
Walls of the nasal septum = ethmoid & vomer bones
Protrusions of the bone = nasal conchae (superior, middle, inferior)
Allows air to swirl in the nasal cavity – airborne particles get trapped in mucus
Cavity is lined with mucous membrane
Mucus is secreted by the paranasal sinuses (=air cavity with epithelium in the skull)
Floor of the nasal cavity = hard palate (roof of the mouth)
3/17/08

5. Function of the Nose Directs air into the nasal passageway
Warms air via blood circulation
Location for olfaction sensation
Traps particles & microbes = non-specific defense
These then get swallowed with mucous
3/17/08

6. Pathway of Air/ O2 – Pharynx and on
From the nasal cavity, air enters internal nares then the pharynx (throat)
Pharynx
Shared by digestive and respiratory systems
It is a muscular tube lined with mucous epithelium
Just behind the nasal cavity = nasopharynx
The oropharynx is located right under the soft palate – base of the tongue at the opening of the throat
It is lined with stratified squamous epithelium (b/c it is shared with the digestive system
Fig. 21.3
3/17/08

7. Pathway of Air/ O2 – Pharynx and on
Laryngopharynx
Below oropharynx = cavity
Opening to esophagus & trachea
Common area for air & food
Stratified squamous epithelium
Next air enters the Larynx
Top of the trachea
Epiglottis = elastic cartilage
Allows distinguish food vs. air
It closes the glottis (opening of the larynx) if food is passing into the pharynx
The ligaments stretch during swallowing to prevent food from entering the nasal passageway
Fig. 21.5
Fig. 21.3
3/17/08

8. Pathway of Air/ O2 – Larynx (& sound)
Cylinder made of cartilage, ligaments & skeletal muscle
Note large pieces of hyaline cartilage
The larynx contains 2 ligaments stretched from cricoid cartilage to thyroid cartilage = vocal ligaments (commonly called “vocal cords”
Air brushes against the vocal cords and creates vibrations = sound
The Larynx is important for air passage and speech
Skeletal muscles lengthen and shorten vocal cords – produces different sounds
Fig. 21.4
3/17/08

9. Pathway of Air/ O2 – Trachea
aka “windpipe”
Tube made of smooth muscle from larynx to bronchi
Supported by cartilage rings
C-shaped cartilage – open at back = flexibility & expansion
Posterior wall – pseudostratified epithelium
Bifurcation at bottom of trachea (into 2)
the bifurcation =carina
Contains the cough reflex center
2 branches = Primary bronchi (to right and left lung)
Cartilage rings support the bronchi
Fig. 21.6
3/17/08

10. Pathway of Air/ O2 – Bronchi
Primary bronchi
Each Primary bronchi branches into secondary (lobar) bronchi
These go to individual lobes of the lung
These then branch into the tertiary (segmental) bronchi
These are branches within each lobe
Branch to bronchioles
End in lobules
The bronchi regulate the air flow through the lungs
Bronchitis = infection/inflammation of the bronchi
Acute bronchitis is usually caused by a virus (sometimes by bacteria)
Cough, mild fever, yellow/green mucous
Fig. 21.9
3/17/08

11. Pathway of Air/ O2 – Lung Collection of lobules containing alveoli
Air sacs = light consistency
Whole lung = paired organ - Right and left side
Each lung is divided into lobes
Right = divided into 3 lobes by fissures
Left = divided into 2 lobes (know names of fissures and lobes for lab)
The shape of the lungs accommodates neighboring organs
Heart is slightly to left = left lung is less broad & has cardiac notch
Right side – liver is just below diaphragm = right lung is shorter
Fig. 21.7
3/17/08

12. Pathway of Air/ O2 – Lung
Flat base at the bottom, pointed apex at the top
Each lung is covered by a pleural membrane on the outside
Review characteristics of pleural cavity
Medial surface of lungs = surface in middle
Entry point for bronchi & blood vessels (Hilus)
Primary bronchus and pulmonary arteries & veins
Fig. 21.7
3/17/08

13. Pathway of Air/ O2 – Lung
Bronchus divides further inside the lungs – to each lobe
Divided into segments within each lobe
Bronchopulmonary segment
Visceral pleura extends into the lung – divides segments into smaller sections
Each section = Pulmonary lobule
Each lobule
Contains a cluster of alveoli
Receives air from the Bronchioles
Lymph vessel circulation
Pulmonary arteries and venules
Each alveolus within each lobule
Hollow air sac
Two or more air sacs may share a common opening = alveolar sac
Recall what you saw in lab…
Fig. 21.9
3/17/08

14. Alveoli In Pulmonary Lobule
Fig. 21.9
3/17/08

15. Pathway of Air/ O2 – Alveoli
Alveoli = location of gas exchange
Each alveolus – is confined – consists of a layer of simple squamous epithelium
Epithelium also contains
Macrophages- to engulf any escaped pathogens
Septal cells – special cells that secrete a liquid called surfactant
A surfactant keeps alveoli from collapsing shut
There is a continuous capillary adjacent to each alveolus
These are connected by fused basement membranes of epithelial cells & endothelial cells
Gas crosses 3 layers
CO2 enters alveolus & O2 enters capillary
3/17/08

16. Alvioli – Capillary Interface
Fig
3/17/08

17. Mechanics of Respiration
Ventilation
= mechanical process
involves the diaphragm and skeletal muscles (intercostal muscles)
Breathing consists of 2 phases:
Inspiration
air is taken into the lungs
Expiration
Air passes out of the lungs
3/17/08

18. Mechanics of Respiration
Air is moving in & out because of pressure gradients
Air flows from high pressure to low pressure…
For air to enter the lungs, pressure should be low in the lungs
EXPANSION of lungs lowers pressure
The Diaphragm contracts – pushed down = opens space in the lungs
External intercostal muscles contract – elevates chest
Pulls on parietal pleura
Pulls on visceral pleura
Expands space into the lung
The pressure gradient forces air into the lungs (insp)
ACTIVE process – powered by muscle
3/17/08

19. Mechanics of Respiration
Inspiration = ACTIVE process – powered by muscle
Expiration = PASSIVE process
Objective = increase pressure in lungs to create high pressure gradient in TO out…
The diaphragm and intercostals relax
Pushes against pleura – close in on lungs
Imagine a full balloon with hands pushing against it
Increased pressure in lungs forces air out
Process of regular breathing
Deep breathing & forced expiration require additional muscles – abdominal muscles
3/17/08

20. Mechanics of Respiration
The amount of air entering during breathing depends on several factors
COMPLIANCE – degree of expandability of lungs
Large compliance – more air enters
Elastic fibers surround alveoli & surfactant in alveoli contribute to compliance & mobility of thoracic cage
Less surfactant – alveoli collapse – decreases comp.
Less elasticity = increases compliance
Emphysema
Shortness of breath, weak at exertion
Destruction of alveolar surface = loss of elasticity
Merged alveoli = larger space, but not enough capillary support, so gas exchange does not support demand
Skeletal disorders
Arthritis or rib injuries reduce compliance
3/17/08

21. Lung mechanics
Fig
3/17/08

22. Lung mechanics
Fig
3/17/08

23. Lung mechanics
Fig
3/17/08

24. Lung mechanics
Fig
3/17/08

25. Lung mechanics
Fig
3/17/08

26. Lung mechanics
Fig
3/17/08

27. Lung mechanics
Fig
3/17/08

28. Mechanics of Respiration
3/17/08

29. Mechanics of Respiration
Air is moving in and
3/17/08

30. Mechanics of Respiration
Air is moving in and out of the lungs due to pressure gradients
We will cover the mechanism in more detail in lecture, but be sure you read the introduction to each lab and to each section/activity…you will be responsible for the information presented there in lab and lecture!
Happy breathing
3/17/08

31. Nose
Fig
3/17/08