14 - Respiratory System

Question 1

What are the 2 subdivisions of the respiratory system, and what do they contain?

Answer 1

1) Upper respiratory system
- nose, nasal cavity, pharynx
2) Lower respiratory system
- larynx, trachea, bronchial tree, lungs

Question 2

What lines the respiratory tracts?

Answer 2

• lined with mucosa (with one exception)
  - all have epithelial tissue + CT
  - epithelial tissue for most = ciliated pseudostratified columnar epithelium (with goblet cells)
  - cilia sweep mucus to esophagus where swallowed
  - connective tissue layer of ALL mucosae = lamina propria

Question 3

Describe the nose

Answer 3

• supported by bone + hyaline cartilage

- nostrils = nares

Question 4

Describe the nasal cavity

Answer 4

• functions:
  a) airway passage (warm + moisten air)
  b) olfaction (smell)
  c) speech (resonance chamber)
  - divided by nasal septum
  - anterior part = hyaline cart
  - posterior part = vomer, ethmoid, maxillae, palatine bones
  - 3 areas
  a) vestibule
  - anterior region
  - lined by skin with coarse hairs (only non-mucous membrane)
  - stratified squamous epithelial because it opens to the outside
  b) respiratory area
  - posterior region
  - mucosa = ciliated pseudostratified epithelium + CT
  - conchae protrude from walls
  - superior
  - middle
  - both part of ethmoid
  - inferior – separate bone
  - inferior to each concha = a nasal meatus (shallow groove)
  - conchae and meatuses cause air turbulence to knock out dust
  - lacrimal duct opens into cavity (just below inferior nasal concha)
  - tears into nasal cavity
  c) olfactory area
  - sense of smell
  - roof of cavity
  - neurons = olfactory receptors

Question 5

Describe the paranasal sinuses

Answer 5

• 8 air-filled spaces in skull
  - paired left and right spaces in:
  - frontal
  - sphenoid
  - ethmoid
  - maxillae
  - open directly into nasal cavity
  - function:
  - warm, moisten air
  - lighten skull
  - sinusitis
  - inflammation of mucous membrane

Question 6

Describe the pharynx

Answer 6

• skeletal muscle lined by mucous membrane
  - 3 regions:
  a) nasopharynx
  - posterior to nasal cavity
  - air passage only
  - contains;
  - pharyngeal tonsil
  - openings:
  - 2 posterior nasal apertures
  - 2 pharyngotympanic (Eustachian) tubes

        b) oropharynx
            - posterior to oral cavity
            - air and food passage
            - stratified squamous epithelium (abrasion)
            - from soft palate to epiglottis
            - contains:
             	- palatine tonsils
                - lingual tonsil
        c) Laryngopharynx 
            - air and food passage
            - stratified squamous epithelium
            - from epiglottis to opening of larynx

Question 7

Describe the larynx

Answer 7

• air passage only
  - made of 9 cartilages
  - all hyaline cartilage (except epiglottis)
  - unpaired cartilages (x3)
  a) thyroid cartilage
  - on anterior wall
  - = Adam’s apple
  b) cricoid cartilage
  - forms complete ring
  c) epiglottis
  - covers glottis during swallowing
  - elastic cartilage
  - paired cartilages (x3)
  a) arytenoid
  - attaches vocal cords
  → don’t need to know the other 2
  - vocal cords = 2 paired folds in the mucosa
  a) vestibular fold
  - = false vocal cords
  - superior fold
  b) vocal fold
  - = true vocal cords
  - inferior fold
  - produce sound by vibration
  - glottis
  - = true vocal cords + opening
  - closes to prevent prevents food + liquid from entering trachea
  - laryngitis
  = inflammation of larynx
  – can arise from infection, irritation

Question 8

Describe the trachea

Answer 8

• connects larynx to main bronchi
  - anterior to esophagus
  - consists of 20 C-shaped pieces of hyaline cartilage
  - open part of C faces esophagus - permits expansion of esophagus

Question 9

Describe the bronchial tree

Answer 9

2 x main bronchi (1o)
5 x lobar bronchi (2o)
many segmental bronchi (3o)
terminal bronchioles
respiratory bronchioles
alveolar ducts

Question 10

How does the muscle / CT content of the bronchial tree change?

Answer 10

Starts with lots of hyaline cartilage, lessens and grows smooth muscle, by bronchioles it is all elasic fibres and smooth muscle.

Question 11

How does the epithelium of the mucosa change throught the bronchial tree?

Answer 11

main bronchi - pseudostratified columnar ciliated epithelium
terminal bronchioles - ciliated simple cuboidal
alveolar ducts - simple squamous

Question 12

Describe the lungs

Answer 12

right and left = separated by mediastinum

	- right lung = 3 lobes
		- superior, middle, inferior
	- left lung = 2 lobes
		- superior, inferior
		- has cardiac notch (where heart lies)
	- pleura = serous membrane
		- visceral - on surface of lung
		- parietal – on inner thoracic wall, superior diaphragm + mediastinum
	- pleural cavity = filled with serous fluid
		- prevents friction when lungs move 
		- holds lungs to thoracic cavity wall

							nasal cavity
							       ↓
							       ↓	conducting zone
							       ↓	(conduct air)
							terminal bronchioles					                                   

								respiratory bronchioles 
								   ↓ 			respiratory
											zone
								alveolar ducts		(gas exchange 	with air)
								   ↓
								alveoli (most gas exchange) 

	- respiratory zone = respiratory bronchioles, alveolar ducts, alveoli
		- O2 enters blood, CO2 enters air (gas exchange occurs mainly in alveoli)

Question 13

Describe the respiratory membrane

Answer 13

• consists of alveolar walls + surrounding capillaries
  - 3 layers = 2 epithelia and their fused basement membranes:
  a) wall of alveolus
  - simple epithelium
  - made of 3 cell types:
  i) type I alveolar cells
  - simple squamous
  - allow gas diffusion
  ii) type II alveolar cells
  - simple cuboidal
  - secrete surfactant
  - allows lungs to expand with ease
  iii) macrophages
  - free-moving across surface of type I cells
  - remove dust + debris
  Note: alveolar pores allow air movement between alveoli
  b) Basement membrane of alveolus + capillary
  c) Wall of capillary
  - simple squamous epithelium (=endothelial cell)

Question 14

Describe bronchial circulation

Answer 14

• bronchial arteries
  - arise from aorta (systemic)
  - carry oxygenated blood to tissues (e.g. bronchi) except respiratory zone
  - returning to heart, blood drains into:
  - bronchial vein (little blood) (to right atrium – systemic)
  - OR pulmonary veins (most blood) (to left atrium – pulmonary)

Question 15

Define a pulmonary edema

Answer 15

• accumulation of fluid in the lungs - between cells and within alveoli

Question 16

Define Tuberculosis (Mycobacterium tuberculosis) (TB)

Answer 16

• thickens respiratory membrane - lung tissue replaced by fibrous CT (scars)
  - decreased lung elasticity and gas exchange area

Question 17

Define a pulmonary embolism

Answer 17

• blockage of pulmonary vasculature

- due to blood clot, arteriosclerosis, air bubbles in vessels, etc.

Question 18

Define a pneumothorax

Answer 18

• entry of air into pleural cavity

- causes lung to collapse

Question 19

Define emphysema

Answer 19

• alveolar walls break down
  - fewer, larger alveoli
  - decreased surface area for gas exchange
  - decreased elasticity (hard to breathe) + recoil (less air out on exhalation

Question 20

Describe ventalation

Answer 20

• muscles are all skeletal
  1) Inspiration (intake of air)
  - diaphragm + external intercostals contract
  2) Expiration (air moves to atmosphere from lungs)
  - diaphragm + external intercostals relax
  - exhaling = passive process