5 Structure and Function of the Airways Flashcards Preview

LSS Respiratory System > 5 Structure and Function of the Airways > Flashcards

Flashcards in 5 Structure and Function of the Airways Deck (40)
Loading flashcards...
1
Q

Q: Which interface is designed for gas exchange? What else does this interface need to be able to do? why?

A

A: Interface between external air and alveolar region for gas exchange

other substances breathed in as well -> must be equipped to defend itself

2
Q

Q: What the 2 main functions of the airways? What facilitates these functions? (3) Describe. (3,2,2)

A

A: conduit to conduct O2 to alveoli; conduct CO2 out of lung = gas exchange

facilitated by

  • mechanical stability : cartilage -> keeps open
    - cartilage is C-shaped with opening at back of trachea for oesophagus (C shaped so doesn’t make it difficult for food to go down) -> allows for bronchoconstriction
    - cartilage is slightly offset compared to each other -> ++ tensile strength)= less easily compressed
  • control of calibre (smooth muscle)
  • protection and “cleansing”
3
Q

Q: Name 7 cell categories.

A

A: Lining cells

Contractile cells

Secretory cells

Connective tissue

neuroendocrine

Vascular cells

Immune cells

4
Q

Q: Name the 4 lining cells.

A

A: Ciliated, intermediate, brush, basal

5
Q

Q: What are contractile cells called? (2)

A

A: Smooth muscle (airway, vasculature)

6
Q

Q: Name 3 secretory cells. Include 2 locations.

A

A: Goblet (resp epithelium and reproductive tracts- are cells in their own right), mucous (specialised epithelium cells), serous (glands)

7
Q

Q: Name 2 connective tissue cells. 3 examples?

A

A: Fibroblast, interstitial cell (elastin, collagen, cartilage)

8
Q

Q: Name 4 neuroendocrine cells.

A

A: Nerves, ganglia, neuroendocrine cells, neuroepithelial bodies

9
Q

Q: Name 3 (+1) vascular cells.

A

A: Endothelial, pericyte, plasma cell (+ smooth muscle)

10
Q

Q: Name 6 immune cells.

A

A: Mast cell, dendritic cell, lymphocyte, eosinophil, macrophage, neutrophil

11
Q

Q: What mixture lines airway epithelium? What does it contain? (9) Produced by?

A
A: Mucus- 
mucins, 
water, 
electrolytes, 
plasma, 
mediators, 
inorganic salts, 
antiseptic enzymes (such as lysozymes), immunoglobulins, 
glycoproteins such as lactoferrin and mucins

goblet cells

12
Q

Q: In airway epithelium, what moves mucus along? process name? What does airway epithelium act as? What are the 2 main cells of airway epithelium?

A

A: movement of mucous by cilia -> mucociliary clearance

physical barrier

  • ciliated
  • goblet
13
Q

Q: What is produced by airway epithelium? (2) Name 6 examples, including what produces it for some.

A

A: production of regulatory and inflammatory mediators

  • NO by NOS
  • CO by hemeoxygenase
  • Arachidonic acid metabolites e.g. prostaglandin
  • Chemokines e.g. ILs
  • Cytokines e.g. GM-CSF
  • Proteases
14
Q

Q: What do ciliated cells contain? What are cilia? structure? role? What lies on top of cilia?

A

A: ++ mitochondria

cilia: have apical “hooks” (engage with mucus); 9+2
metacronal beating to move mucous to back of throat with particles etc.

mucous layer on top of cilia

15
Q

Q: What do goblet cells contain lots of? What happens to this structure? (2) What is the structure of this structure outside of the goblet cell?

A

A: mucin granules in highly condensed form

hydrates when fuses with cell membrane -> expelled

when they are released- increase in size by 600 (many 100) fold (take in water)

16
Q

Q: What is also part of airway epithelium? where? (3) What do these structures contain and what do they do? (3)

A

A: Airway submucosal glands

  • between 2 epithelial (or goblet) cells
  • extend down past basal lamina
  • > basal part embedded in smooth muscle layer
  • mucous cells secrete mucous
  • serous cells secrete antibacterials (e.g. lysozyme)/
  • glands also secrete water and salts (e.g. Na+ and Cl-)
17
Q

Q: What do smooth muscle cells provide (functions) in human airways? (3) What do they secrete? (3) how much?

A

A: -Structure

  • Tone (airway calibre): contraction; relaxation
  • Secretion: mediators; cytokines; chemokines (little) -
18
Q

Q: What can inflammation of smooth muscle cells in airways cause? Example? Explain (3)

A

A: contributes to disease process

asthma ->
hypertrophy -> impact on calibre of lumen + upregulates production of mediators

19
Q

Q: What percentage of cardiac output goes to airway vasculature? What circulation is this? What is the rate of blood flow to airway mucosa (mucous membrane)? How does this compare to other tissues?

A

A: 1-5%

trachea-bronchial circulation

100-150ml/min/100g tissue (amongst highest to any tissue) = lots of input

20
Q

Q: Where do bronchial arteries arise from? (3) What are the 2 types of airway vasculature circulations? Where does blood return to for each one? (1,2)

A

A: bronchial arteries arise from many sites on: aorta, intercostal arteries and others

  • blood returns from tracheal circulation via systemic veins
  • blood returns from bronchial circulation to both sides of heart via bronchial and pulmonary veins
21
Q

Q: What does the subepithelial microvascular network have? Functions? (6)

A

A: -good gas exchange

  • contributes to warming of inspired air
  • contributes to humidification of inspired air
  • clears inflammatory mediators
  • clears inhaled drugs
  • supplies airway tissue and lumen with inflammatory cells
  • supplies airway tissue and lumen with proteinaceous plasma (plasma exudation)
22
Q

Q: What is plasma exudation in terms of airways? How does it occur? (4)

A

A: the supply of airway tissue and lumen with proteinaceous plasma

post-capillary venular endothelial cells contract with different stimuli -> pull away from each other -> plasma leaks out through gap -> tissue

23
Q

Q: What controls plasma exudation in airways? (2-1,2)

A

A: sensory nerves (despite motor function)

inflammatory mediators (histamine, platelet activating factor)

24
Q

Q: How is airway function controlled? (4) Describe each. (2,4,2,2)

A

A: nerves: parasympathetic (cholinergic); sensory

  • regulatory and inflammatory mediators: histamine; arachidonic acid metabolites (e.g. prostaglandins, leukotrienes); cytokines; chemokines
  • proteinases (e.g. neutrophil elastase)
  • reactive gas species (e.g. O2-, NO)
25
Q

Q: What can cause a respiratory disease? 3 example diseases. What do they result in? (3)

A

A: loss of airway function

asthma; COPD; CF (CF is an autosomal recessive condition)

Airway inflammation,
airway obstruction
airway remodelling

26
Q

Q: Asthma as a respiratory disease. What is it? What does it mainly lead to? How long does this last? but? How can it be manifested? (3)

A

A: Clinical syndrome characterised by increased airway responsiveness to a variety of stimuli -> airways obstruction

Airflow obstruction varies over short periods of time and is reversible (spontaneously or with drugs)

Dyspnoea (difficult/laboured breathing), wheezing and cough (varying degrees)

27
Q

Q: Describe asthma mechanism. Starts from? Leads to? (4) 4 examples for 1. Result? Primary inflammatory cells involved?

A

A: Airway inflammation

  • > remodelling
    - mucus plug in lumen
    - epithelial fragility
    - basement membrane thickening
    - ++ size of submucosal glands;
  • > increase in size of smooth muscle
  • > vasodilation (“congested” vessels)
  • > cellular infiltration

->airway wall thrown into folds (due to SM contraction) = bronchoconstriction

eosinophils

28
Q

Q: Where in the body are lungs? What leads to them?

A

A: thoracic cavity

trachea that bifurcates into 2= bronchi and keep dividing into 2-> DICHOTOMOUS BRANCHING

29
Q

Q: What happens as airways branch? until? What do they lead to? where?

A

A: As the airways branch, they get narrower and narrower until you get to the periphery

The airways lead down to the alveolar region where gas exchange takes place

30
Q

Q: How much air do we inhale each day?

A

A: 12000 L of air

31
Q

Q: Describe a cross section of an airway-trachea. (10)

A

A: lumen

mucus

cilia

ciliated cells/goblet cells

submucosa

      containing blood vessels- systemic circulation: trachealbronchial cells

submucosal glands (lower part of the submucosal gland is embedded in the smooth muscle)

smooth muscle

submucosa?

cartilage

32
Q

Q: How do smooth muscle cells and submucosal glands related?

A

A: when the smooth muscle contracts it squeezes the submucosal gland - they work in tandem

33
Q

Q: How much mucous do you swallow on a normal day from the airways?

A

Q: 10mL

34
Q

Q: Describe cilia movement.

A

A: there are different fields of cilia that are linked together

beat according to mechachronal rhythm

  1. first field of cilia beat left
  2. then first field do recovery stroke to get back (go more lateral)
  3. meanwhile second field beats cilia while 1st is doing recovery stroke
  4. pattern continues
35
Q

Q: What is normal muscle tone?

A

A: always slightly contracted (even though not being contracted makes breathing easier)

  • gives it somewhere to go if airways need to dilate (theory)
  • or it could react more quickly if it’s already a little constricted
36
Q

Q: How do smooth muscle cells in airways change with inflammation?

A

A: structure: hypertrophy- get more smooth muscle -> may give more tone

secretion: more secretions
- cytokines
- chemokines
- adhesion molecules => all 3 are inflammatory cell recruiters

37
Q

Q: Describe airway innervation in terms of eating peanuts if you have an allergy and back to normal to. (5) How does this differ from other animals?

A

A: 1. Some thing (like a peanut) can enter the airway and activate the sensory pathway

  1. sensory pathway either leads to spinal cord A or brain stem B
  2. A: response pathway back to smooth muscle= get relaxation via NO production (adrenalin from adrenal gland also has this effect) -> not considered sympathetic pathway: we have nerves that contain NOS (nitric oxide synthase)

dilation of aiways

  1. B: parasympathetic response pathway back to smooth muscle= contraction = cholinergic pathway = most important motor pathways in the airways (both input and output of this go through vagus nerve)

BRONCHOCONSTRICTION (to stop the peanut from going down too far)

Other animals have been shown to have sympathetic pathways that cause relaxation

38
Q

Q: Which pathway causes the opening up of the airway?

A

A: NO is the neurotransmitter of the neuronal pathway that causes the opening up of the airways

39
Q

Q: Describe the cholinergic mechanism in the airways. (6)

A

A: 1. Irritants in airway

  1. cause an impulse to pass up the sensory fibre -> vagus nerve-> nodose ganglion to CNS (brainstem)
  2. causes a CHOLINERGIC REFLEX: parasympathetic nerve comes back down in vagus nerve -> parasympathetic ganglion -> then 3 effects come off (2 off them include post ganglionic neuron with ACh as NT)
  3. contracts smooth muscle
  4. causes secretion of mucus
  5. You may also get a little bit of vasodilation

The contraction and secretion is under cholinergic control

There is smooth muscle around the airways which contracts in response to acetylcholine

40
Q

Q: Name 6 inflammatory cells in airways. Role?

A

A: eosinophils, neutrophils, macrophages, mast cells, T lymphocytes and ‘structural cells’ eg SM cells that become inflammatory (start secreting etc)

These cells produce a variety of mediators