Structure and function of airways

Question 1

Explain the structure of the airway

Answer 1

Dichotomous branching

has C shape cartilage that gives it mechanical stability and allow oesophagus to run down posteriorly

Question 2

What holds tha alveolar sac together and binds it to bronchioles

Answer 2

Surfactant

Question 3

Describe the component of an alveolar unit and what is the function of each cell

Answer 3

• Type 1 cell- thin and delicate barrier for gas exchange

macrophage and stromal cell (fibroblast)

• type 2 cells- replicate Type 1 cells. It also produce surfactants which reduce surface tension. It also produce anti proteases and carries out xenobiotic metabolism( removing toxins )

Question 4

What are the basic functions of the respiratory airways

Answer 4

1. Conduit pities to conduct Oxygen into the alveoli
2. conduct CO2 out of lungs after gas exchange

Question 5

Describe the content and significance of the nasal passages

Answer 5

Pharynx- has 3 segments; common passageway for foods, liquids and air

conchae- highly vascular; contribute to warming and humidification of nasally inhaled air.

Nasal hairs filters out large particles

Question 6

What facilitates the airways in performing it’s functions?

Answer 6

Cartilage- provide mechanical stability

control of calibre (opening and closing) by smooth muscle

protection and cleansing by epithelium

Question 7

Describe the organisation of the airway form outermost to innermost

transverse section

Answer 7

Outermost- cartilage rings and smooth muscle beneath it

blood vessel then sub mucosal gland, goblet cells and ciliates cell

Question 8

Draw the side view structure of the air way

Answer 8

Question 9

What are the different types of cells in airway

Answer 9

• Ciliated, brush cell- lining cells
• smooth muscle - contractile cells
• fibroblast, interstitial cell- connective tissue
• nerves, ganglia - Neurendocrine
• pericyte, plasma cell- vascular cells
• mast cell, dendritic cell- immune cells

Question 10

What does goblet cells secret?

Answer 10

Mucin (highly condensed) that becomes enlarged quickly by takin water (mucin granules makes mucin)

the mucin becomes mucus

Question 11

Why does cilia cells have a lot of mitochondria?

Answer 11

Need energy to move and move mucus up into the mouth

Question 12

What does sub mucosal glands secrete

Answer 12

• Mucous acini has mucus cells- this makes mucus
• serous acini has serous cell- make anti bacterial enzymes
• Glands also secrete water and salts

Question 13

What is the structure of a cilia

Answer 13

Anchoring proteins

Axoneme (microtubules)

apical hooks

9+2 nature structure in transverse section

Question 14

What are the functions of the airway epithelium

Answer 14

• Secretion of mucin, water and electrolytes
• movement of mucus by cilia- mucociliary cleaance
• physical barrier
• production of regulatory and inflammatory mediators like Nitric oxide,

Question 15

What enzyme makes Nitric oxide? How can you test for it?

Answer 15

Nitric oxide synthase

brown staining using anti-NOS antibody

Question 16

What is the inflammatory secretory response by airway smooth muscle cell

Draw

Answer 16

Question 17

Describe the airway vasculature and describe what perfuses it . What % of cardiac output?

Answer 17

Supplied by bronchial and tracheal arteries from aorta and intercostal arteries

1-5% cardiac output

blood flow among highest of any tissue- 100-150mL/min/100g

Question 18

What are the fucntions of the tracheo-bronchial circulation

Answer 18

Question 19

What controls airway function?

Answer 19

• Nerves- PNS,
• Regulatory and inflammatory mediators - like histamines, cytokines etc
• Proteinases
• Reactive gas species (NO)

Question 20

Draw the autonomic innervation of the airways

what is the significance in humans

Answer 20

Humans don’t have any sympathetic neuronal relaxation signal

Only NO is used for relaxation and adrenaline from THE BLOOD

Question 21

Name some regulatory-inflammatory cells and their mediators and functions

Answer 21

Cells make more than one mediator and mediators do more than one thing

Question 22

Describe the pathophysiology of asthma

Answer 22

Increased airway responsiveness to variety of stimuli; leads to airway obstruction

obsruction varies over short period of time and it’s reversible spontaneously or with drugs

there’s air way inflammation and remodelling of the airway

lumen is blocked by mucus

eosinophils- main cells responsible

Question 23

What are the 3 different response that airway smooth muscle carries out in inflammation

Answer 23

Structural - hypertrophy and proliferation

Tone- contraction and Ella action; a protective mechanisms

Secretion- makes mediators, cytokines and chemokines