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BMS 264: Biomedical Physiology > Lecture 18: Respiratory 1-structure, Function, Ventillation > Flashcards

Lecture 18: Respiratory 1-structure, Function, Ventillation Flashcards

0
Q

Be able to label the diagram on slide 7

A

Yep

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1
Q

What’s the difference between internal and external respiration?

A

Internal respiration:

  • cellular respiration
  • intracellular process: O2 is used by mitochondria to generate ATP through oxidative phosphorylation.
  • CO2 and H2O produced as waste products

External respiration: involves 4 processes

  1. Pulmonary ventilation
  2. Gas exchange (lungs)
  3. Transportation of O2 and CO2
  4. Gas exchange
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2
Q

What are the functions of the upper respiratory tract?

A
  • conducts air to and from lower respiratory tract
  • warms and moistens air
  • nasal cavities also filter and clean the air (nasal hairs, mucus and cilia)
  • larynx also
    • prevents airway collapse (cartilage)
    • prevents food entering LRT (epiglottis)
    • cough reflex
    • initiated voice production
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3
Q

Divisions of the upper and lower respiratory tracts.

Ie what structures are contained in each?

A 
Upper: 
-oral cavity, nasal cavity 
-pharynx
-larynx 
(Conducting zone)

Lower respiratory tract:

  • trachea
  • bronchi
  • bronchioles
  • alveoli (respiratory zone)
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4
Q

Conducting zone:

What’s is responsible for?

A
  • conducts air to and from the respiratory zone
  • warms, humidifies and cleans air (contains goblet cells, secret mucus) and cilia
  • NO GAS EXCHANGE
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5
Q

Trachea (LRT, conducting zone)

Functions

A

Keeps airways open during inspiration
-cartilage rings prevent airway collapse when lungs at low pressure during inspiration
Cleans air via mucus escalator
-cilia beats mucus and foreign particles towards pharynx for swallowing
Initiates cough reflex in response to irritants

Smoking paralyses the cilia so smokers must cough to remove mucus

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6
Q

Bronchi (LRT, conducting zone)

Functions:

A
  • distribute air into and though out lungs
  • keep airway open during inspiration- cartilage rings
  • clean air via mucus escalator ➡mucus secreting goblet cells and cilia
  • cough reflex
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7
Q

Bronchioles (LRT, conducting/ respiratory zones)
-bronchioles transit between conducting and respiratory zones
-small tubes of small muscle
-contain no cartilage
Function?

A
  • Distribute air through lungs
  • clean air via mucus escalator (goblet cells and cilia)
  • can adjust airflow (diameter can change; regulated by ANS)
  • respiratory bronchioles are involved in gas exchange
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8
Q

LRT: respiratory zone

What it do?

A

Site of gas exchange

  • includes respiratory bronchioles and alveoli
  • gas exchange maximised by:
    • large surface area
    • thin walls
    • no cartilage
    • no goblet cells (no mucus)
    • sparse/ absent cilia
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9
Q

Alveoli (LRT, Respiratory zone)

Structure and function?

A

-tiny, sac-like structures
-arranged in clusters (alveolar sacs) located at the end of alveolar ducts
-functions is gas exchange
2 types of alveolar cells
Type 1:
Epithelial cells that form single layer structure over alveolus
Type 2 alveolar cells:
-synthesis surfactant

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10
Q

Respiratory membrane:

A 
Separates air in alveoli from blood 
Comprised of: 
-type 1 alveolar epithelial cells 
-basement membrane 
-capillary endothelial cell 
Membrane is VERY thing
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11
Q

Look at summary of airway structure and function, best tool to study

A

Do it

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12
Q

Structure of the thoracic cavity

A

Lungs located within the thoracic cavity, encased by the chest wall
Each lung is encased in its own pleural sac
Pleura: lining made up of epithelial cells and connective tissue

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13
Q

What are the functions of the intrapleural fluid?

A
  1. Provides lubrication for friction free lung movement
  2. Generates surface tension that:
    - prevents separation of pleurae
    - helps hold lungs against chest wall in a semi-inflated state at rest
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14
Q

What is pulmonary ventilation?

How is airflow driven?

A

Getting air in and out of lungs.

By pressure gradients?

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15
Q

Boyle’s law:

A

When volume decreases pressure increases.
The pressure of a gas is defined as the force that gas excerts on the walls of its container
P1V1= P2V2

16
Q

What are the 4 pressures that influence gas exchange?

A 
Atmospheric pressure (Patm)
Alveolar pressure (Palv)
Intrapleural pressure (Pip)
Transpulmonary pressure (Ptp)
17
Q
  1. Atmospheric pressure
  2. Alveolar pressure
    Describe each
A
  1. Atmospheric:
    -760mm
  2. Alveolar pressure:
    -pressure inside alveoli changes during breathing due to:
    A) change in lung volume
    B) airflow into or out of lungs
    As as atmospheric pressure is quite constant, alveolar pressure determines air flow
18
Q 
Intrapleural pressure (Pip)
Transpulmonary pressure
A

Intrapleural pressure:
-pressure inside pleural cavity
-varies with respiration by is always less that (Palv)
-Pip is always negative due:
-inward recoil of lungs (inherent elastic properties + surface tension in alveoli)
-outwards recoil of rib cage (compressed at rest)
Remember that each lungs and its pleural sac is separate of the other so there are independant of each other.

Transpulmonary pressure:
Is the difference between Palv and Pip
Ptp= Palv- Pip
=0 - (-4) = +4mmHg
Always is positive under normal conditions
-Ptp is the force that keeps the lungs inflated

19
Q

Pathophysiology: Pneumothorax

A
  • is lung collapse due to presence of air in the pleural space
  • intrapleural pressure will become the same as atmospheric pressure
  • transpulmonary pressure becomes 0mmHg
  • no force to keep lungs inflated, lungs collapse
20
Q

Mechanics of pulmonary ventilation

Talk through the volume changes

A
  1. Muscles change volume of thorax
  2. Change in intrapleural pressure and transpulmonary pressure
  3. Change in lung volume
  4. Change in alveolar pressure
  5. Airflow
21
Q

Muscles of pulmonary ventilation:
What muscles contract to expand the chest cavity?
What muscle contract to reduce the chest cavity?

A

Muscles of pulmonary ventilation:
What muscles contract to expand the chest cavity?
External intercostal muscles:
-pull ribs up and out when the contract
Diaphragm:
-pulls down when it contracts, increasing the size of the thoracic cavity
What muscle contract to reduce the chest cavity?
Internal intercostals:
-pull ribs inwards
Abdominal muscles:?
-pull ribs inwards when they contract
-causes intestines and liver to push upwards on diaphragm

22
Q

Mechanisms of inspiration (breathing in) cellular level

A
  • Increased AP firing in somatic neurons controlling inspiratory muscles
  • diaphragm and external intercostals contract
  • chest wall expands (diaphragm moves down, ribs move up and out)
  • intrapleural pressure decrease, increasing transpulmonary pressure
  • lung volume increases (suction created pulls lungs outwards)
  • alveolar pressure decreases (due to increases lung volume)
  • air flows into alveoli down pressure gradient until Palv= Patm
23
Q

Expiration

Passive and active

A

Passive:

  • occurs during quiet normal breathing
  • doesn’t require energy
  • involves relaxation of muscles that were contracted during inspiration

Active inspiration:
-strong fasted contraction of lungs. Important during exercise and disease
/involves internal intercostal and abdominal muscles contracting.

BMS 264: Biomedical Physiology (33 decks)

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