Module 21 respiratory system (ventilation) Flashcards
(26 cards)
What are the four main functions of the respiratory system?
- Regulate pH levels
- Bring in oxygen and get rid of carbon dioxide
- Vocalization
- Protect from inhaled pathogens
What is the pathway of air into the body?
- Nasal/oral cavity
- Pharynx
- Larynx
- Trachea
- Primary bronchi
- Bronchioles
- Alveolar ducts
- Alveoli
How can bronchioles change shape?
They are surrounded by smooth muscle.
What are the defense mechanisms?
Cells can secrete mucous and other cells have cilia like projections that sweep the mucous up into the pharynx where it can be swallowed.
Type I alveolar cells
An alveolar sac is made up of a thin layer of Type I alveolar cells. These cells are thin and flat which minimizes the amount of distance gas has to travel during simple diffusion.
Type II alveolar cells
These are cells that secrete surfectant
Where is the capillary located in the alveolar cells?
It’s located very close to the Type I alveolar cells.
What controls breathing? What controls the contractions of the diaphragm?
Motor neurons which use acetylcholine as the neurotransmitter.
Bulk flow
Air moves from areas of high pressure to areas of low pressure.
Intra-alveolar pressure (P alv)
The pressure within the alveoli
What is the pressure in the atmosphere and the alveoli when we inhale?
P(atm) is greater than the P(alv)
What is the pressure in the atmosphere and the alveoli when we exhale?
P(alv) is greater than in the P(atm)
Why do the lungs increase volume?
Increase the volume (makes more room for gas particles)
The pressure must decrease below the atmospheric pressure. The lungs have lower pressure compared to the atmosphere.
Why do the lungs decrease volume?
By decreasing the volume past the atmospheric pressure it forces air to exit the lungs. The lungs have higher pressure compare to the atmosphere.
What controls lung volume?
Diaphragm and the intercostal muscles
Lung compliance
Refers to the ability of the lungs to stretch. A higher lung compliance means its easier for the lungs to stretch out and easier to change lung volume and inhale.
What is lung compliance affected by?
- Elasticity of lung tissue (allows lungs to return back to original shape)
- Surface tension inside alveoli
Emphysema
This destroys the elastic fibers. While compliance may increase; the ruined elasticity prevents the lungs from returning to the original shape. This affects the ability to properly get the air out of the lungs.
How does pulmonary fibrosis affect the lungs?
The formation of the scar tissue negatively impacts the lung compliance (ability to expand).
How does surfactant reduce tension?
There is a thin layer of water lining the inside of the alveoli. The surface tension produced by this thin layer of water creates hydrogen bonds that resists the expansion of the lungs. Surfactant which is composed of proteins and lipids lowers this surface tension and allows for expansion making it easier to inhale.
Relaxed diaphragm/releaxed intercostals
The diaphragm is in the upwards position. Upside down u-shape is very evident. This supports exhalation of the air because lung volume decreases and the air is pushed out.
Contracted diaphragm/contracted intercostals
The diaphragm moves the lungs downwards and the intercostals move the lungs outwards to increase lung volume so air enters.
Why is fluid build up in the lungs dangerous?
It increases diffusion distance for gas exchange.
How does coronavirus impact the lungs?
The immune system response to covid-19 hurts gas exchange. Type I & II alveolar cells are destroyed
1. Alveolar collapse due to loss of Type II surfactant cells
2. Less oxygen enters the blood stream due to lack of Type I cells
3. More fluid enters the alveolus.
