Unit 14: Respiratory System

Question 1

Overview of the respiratory system

Answer 1

Main functions:
- ventilation - air movement into and out of lungs
- exchange of gases (O2 and CO2) btw. lungs and blood
Two subdivisions:
1) Upper respiratory system = nose, nasal cavity, pharynx
2) Lower respiratory system = larynx, trachea, bronchial tree, lungs

Mucosa of most of respiratory tract is ciliated pseudostratified epithelium w goblet cells sitting on the lamina propria (exceptions are indicated in the notes below)
- CT layer of ALL mucosa = lamina propria, and tissue subtype = loose areolar
- goblet cells secrete mucous
- cilia sweep mucous to esophagus where swallowed

Question 2

What are the respiratory system organs?

Answer 2

Nose, nasal cavity, paranasal sinuses, pharynx (throat), larynx (voice-box), trachea, lungs, bronchial tree, and respiratory membrane.

Question 3

Info on nose

Answer 3

• supported by bone and hyaline cartilage
• nostrils are called nares

Question 4

Info on nasal cavity

Answer 4

Functions:
a) airway passage (warms, moistens, and filters air)
b) olfaction (sense of smell)
c) speech (resonance chamber)

Divided by nasal septum:
a) anterior part = hyaline cartilage
b) posterior part = vomer, ethmoid, maxillae, palatine bones

3 areas (next card)

Question 5

What are the 3 areas of the nasal cavity?

Answer 5

a) vestibule (entrance area)
- anterior region
- no mucosa; lined by thin skin w/ hair that filters particles (e.g. dust, pollen)

b) respiratory area
- posterior region
- CHONCHAE protrude medially from the lateral walls of nasal cavity
- superior (projection of ethmoid)
- middle (projection of the ethmoid)
- inferior (separate bones referred to as the inferior nasal
chonchae)
- air passes through nasal meatuses (channels) that are btw. the nasal chonchae
- chonchae and meatuses cause air turbulence that helps to humidify air and trap dust/pollen on the ciliated epithelium
- NASOLACRIMAL DUCT connect the medial region of eye to the inferior nasal meatus, allowing lacrimal fluid (which includes tears) to drain into nasal cavity

c) olfactory area
- found in roof of nasal cavity
- mucosa contains olfactory neurons that are sensory receptors for the sense of smell

Question 6

Info on paranasal sinuses

Answer 6

= 8 air-filled spaces in skull
a) paired L and R spaces in: frontal, sphenoid, ethmoid, maxillae
- open directly into nasal cavity
- function = warm, moisten air
- sinusitis = when the mucous membrane becomes inflamed due to infection

Question 7

Info on pharynx (throat)

Answer 7

Wall are formed of skeletal muscle lined by mucous membrane. Divided into 3 interconnected regions (from superior to inferior):

a) nasopharynx
- located posterior to nasal cavity
- passageway for air only
- contains:
- pharyngeal tonsil located on posterior wall
- openings:
- 2 posterior nasal apertures - connect nasal cavity to
nasopharynx
- 2 pharyngotympanic (auditory) tubes - connect middle
ear to nasopharynx
b) oropharynx
- posterior to oral cavity
- epithelium of mucosa is a stratified squamous epithelium
- passageway for both air and food from soft palate to top of epiglottis
- contains:
- palatine tonsils
- lingual tonsil
c) laryngopharynx
- posterior to the larynx - from the epiglottis to the opening of the larynx
- epithelium of mucosa is a stratified squamous epithelium

Question 8

Info about larynx (voice-box) “la la la - LArynx”/voice box)

Answer 8

• anterior to laryngopharynx
• air passageway that connects the pharynx to the trachea
• composed of 8 hyaline cartilages and 1 elastic cartilage (epiglottis):
  
  • epiglottis = flexible, covers the glottis during swallowing to prevent food from entering the larynx
• vocal cords (ligaments) are 2 sets of paired folds under the laryngeal mucosa in the mid-larynx
  a) vestibular folds = superior, called the false vocal cords,
  helps close the glottis
  b) vocal folds = inferior, called the true vocal cords,
  produce sound by vibration
• glottis
  a) includes the vocal folds (true vocal cords) and the
  opening btw. them
  b) closes to prevent food and liquid from entering trachea
• laryngitis = inflammation of larynx due to infection or irritation

Question 9

Info about trachea

Answer 9

• anterior to esophagus
• connects larynx to main bronchi (the 2 main bronchi are branches off trachea leading to each lung)
• passageway for air only
• consists of 20 C-shaped pieces of hyaline cartilage
  
  • open part of C faces esophagus - permits expansion of
    esophagus

Question 10

Info about the lungs

Answer 10

• R and L lungs are separated by mediastinum
• R lung = 3 lobes (superior, middle, inferior)
• L lung = 2 lobes (superior, inferior), and has cardia notch (where heart lies)
• pleura = serous membrane
  a) visceral - on surface of lung
  b) parietal - on inner thoracic wall, superior diaphragm and
  mediastinum
• pleural cavity = filled w/ serous fluid
  a) prevents friction when lungs move
  b) holds lungs to thoracic cavity wall

Question 11

Info about the bronchial tree

Answer 11

• connects trachea to alveoli of lungs
• extends from L and R main bronchi to alveolar ducts
• air passageway that repeatedly branches into smaller and smaller passageways

Question 12

What does the bronchial tree consist of?

Answer 12

a) conducting zone structures
i. 2 Main (primary/1st level) bronchi (L and R)
ii. 5 Lobar (secondary/2nd level) bronchi - 3 on R, 2 on L
iii. Segmental bronchi (multiple levels of branching)
iv. Terminal bronchioles (multiple levels of branching)
- epithelium of mucosa transitions from ciliated pseudostratified epithelium in larger bronchi to ciliated simple cuboidal epithelium in the terminal bronchioles

b) respiratory zone structures
- site of gas exchange (oxygen enters blood and carbon dioxide exits blood in these structures)
- consists of:
i. Respiratory bronchioles (multiple levels of branching)
ii. Alveolar ducts (tips of bronchial tree)
iii. Alveoli (millions - NOT PART OF BRONCHIAL TREE) = honeycomb-like chambers, main site of gas exchange, form part of respiratory membrane
- epithelium of mucosa transitions from ciliated simple cuboidal epithelium in respiratory bronchioles to simple squamous in the alveolar ducts

Question 13

Info about respiratory membrane

Answer 13

3 layers = 2 epithelia and their fused basement membrane:
a) wall of alveolus = simple epithelium; made of 2 cell types:
i. Type I alveolar cells = simple squamous, allow gas
diffusion
ii. Type II alveolar cells = simple cuboidal, secrete
surfactant = molecule that covers inner surface of
alveoli; reduces attractive forces btw. water molecules
making it easier for alveoli to expand during inhalation
- ALVEOLAR PORES (openings) allow air mvmt. btw. adjacent
alveoli
- macrophages - freely move btw. blood and alveoli; remove
dust, cellular debris, and pathogens
b) basement membranes of alveolus and capillary
c) wall of capillary = simple squamous epithelium (=
endothelium)

Question 14

What are the two routes for blood supply to the lung?

Answer 14

1) Pulmonary circulation
2) Bronchial circulation
*see notes for flow charts

Question 15

Outline of pulmonary circulation = blood TO BE oxygenated

Answer 15

RV
to
pulmonary trunk
to
pulmonary arteries
to
capillaries in respiratory potion of lungs (become oxygenated)
to
pulmonary veins
to
LA

Question 16

Info about bronchial circulation

Answer 16

• = subdivision of systemic
• blood TO NOURISH lung tissue
• bronchial arteries
  
  • arise from aorta (systemic)
  • carry oxy. blood to lung tissues (e.g. bronchi) except respiratory portion
• returning to heart blood drains into:
  
  • bronchial vein (little blood) (to RA - systemic)
  • OR pulmonary veins (most blood) (to LA - pulmonary)

Question 17

What is pulmonary edema, pulmonary embolism, inspiration, and expiration

Answer 17

1) pulmonary edema = accumulation of fluid in the lungs - btw. cells and w/in alveoli
2) pulmonary embolism = blockage of pulmonary vasculature; results from blood clots, arteriosclerosis, air bubbles in vessels, etc.
- inspiration = intake of air (diaphragm and external intercostals contract)
- expiration = air moves TO atmosphere from lungs (diaphragm and external intercostals RELAX - exhale = passive)