Non-Respiratory Functions of the Lungs

Question 1

Non-respiratory functions:

Answer 1

• warm and himidify air
• olfaction (sensation of smell)
• filtration of blood at the pulmonary capillaries
• vascular reservoir
• metabolic functions of pulmonary tissue
• Phonation
• Respiratory system compoenents used to build abdominal pressure (Valsalva maneuver)
  
  • to assist with micturition, defecation and child birth

Question 2

What is a valsalva maneuver?

Answer 2

• Straining against a closed glottis
  
  • bearing down

Question 3

Characterize the Nose’s role in warming, humidfying, and filtering air

Answer 3

• Important function of the nasal cavity and pharyges is to warm, moisturize, and filter air before it reaches the lungs
• Air inspired through the nose will be:
  
  • heated to body temperature
  • fully saturated by the time it reaches the bronchioles and alveoli
• Prevents
  
  • dehydrations of the lower respiratory tract
  • reflex bronchocontriction
    
    • lower respiratory tract is exposed to cold air (Exercise-induced asthma)
• Temperature and humidity control is dependent on:
  
  • large surface area of the nasal and pharyngeal mucosa

Question 4

how does air temperature and humidity change with flow

Answer 4

• humidity is fully saturated at 37 degrees
• Expiration causes a drop in humidity=conserve water

Question 5

Why are the nasal turbinates and septum highly vascularized?

Answer 5

Heat exchange and water conservation

Question 6

Describe the olfactory function of respiratory system

Answer 6

• Olfactory receptors are in teh posterior nasal cavity
  
  • not in: trachea, bronchi, or alveoli
• Can sniff to detect dangerous substances
  
  • rapid shallow breathing bring gases in contact with olfactory sensors without bringing them into the lungs

Question 7

How does blood filtration occur in pulmonary capillaries?

Answer 7

• small capillaries (pulmonary capillaries=6 um diameter) act as a filter to protect the systemic circulation
  
  • traps particles that enter mixed venous blood as a result of natural processes, trauma, or therapies

Question 8

Vascular Reservoir

Answer 8

• Pulmonar circulation= blood reservoir for the left ventricle/systemic circulation
  
  • when Right cardiac output decreases, the 500ml of blood in pulmonary circulation can be used to fill the left ventricle and maintain left cardiac output to the systemic circulation
  • adequately perfuse vital organs/tissues
• Pulmonary vasculature is highly destensible
  
  • handle variations in venous return (recruitment and distenstion)
  • when Right cardiac output increases, the pulmonary vasculature can accept additional blood volume without increasing pulmonary arterial pressure
    *

Question 9

How would the pulmonary blood volume change under the following circumstances:

• postural: Supine to erect
• ventilatory: Valsalva maneuver
• hypo/hyper-volemia: (changes in blood volume)

Answer 9

• Postural
  
  • go down due to gravity
  • blood goes to left side of heart to keep BP higher in brain
• Ventilatory:
  
  • blood volume decreases when you increase pressure
• Hypo/hyper-volemia:
  
  • increase in blood volume=increase in blood in lungs
  • decrease in blood volume=decrease in blood in lungs

Question 10

Metabolic functions of the lung:

Answer 10

• Lungs form chemical substance and release locally:
  
  • pulmonary surfactant
  • release of histamine and serotonin from mast cells in response to pumonary embolism or anaphylaxix
    
    • cause bronchoconstriction and may initiate cardiopulmonary reflexes
  • many other substances are stored in the lungs and may be released

Question 11

What drugs are metabolized by the lungs?

Answer 11

• Pulmonary extraction of drugs:
  
  • transfer of a drug from the systemic circulation into the lungs
• Pulmonary endothelium
  
  • primary site of binding or metabolism of drugs
  • buffers teh concentration in the systemic circuation

Question 12

How do lungs metabolize xenobiotics?

Answer 12

• Phase 1 reactions: Oxidation/reduction
  
  • can generate metabolites that are more reactive than parent compound
  • lungs have a lot of cytochromies p450
  • Bioactivation: Reactive Oxygen species
• Phase II reactions: Conjugation
  
  • generate more water-soluble and less active metabolites
  • bioactivation: Free radicals, Electrophiles
• Phase III: Elimination
  
  • Bioactivation: Reactive conjugates

Question 13

What are xenobiotics?

Answer 13

toxic, mutagenic, and carcinogenic chemicals