Week 1 - Respiratory system Flashcards
What are lungs protected by?
Ribcage
What does our ventilation system do? And why?
Moves air in and out of lungs.
-This provides sufficient area for gas exchange in alveoli
Main components of air?
Oxygen, Carbon dioxide, Nitrogen, Water vapour
What are the percentages of air components during inspiration?
Nitrogen - 78%
O2 - 21%
CO2 - 0.04%
Water vapour - variable
What are the percentages of air components during expiration?
Nitrogen - 78%
O2 - 12%
CO2 - 4%
Water vapour - increased
Steps for what happens during Inspiration?
- Intercostal muscles contract - so rib cage moves up and out.
- Diaphragm contracts - flattens and moves down.
- Thoratic cavity increases so air pressure is reduced
- Creates pressure gradient and air from an area of higher pressure in atmosphere moves to thoratic cavity, an area with lower pressure. As a result air moves down trachea - bronchi - bronchioles - alveoli.
- Oxygen diffuses through alveolar membrane to blood capillaries. CO2 diffuses from blood capillaries across alveolar membrane into alveoli.
Steps for what happens during Expiration?
- Intercostal muscles relax - so rib cage moves down and inwards.
- Diaphragm relaxes/recoils - stops being flat and moves up into dome shape.
- Thoratic cavity decreases so air pressure is increased.
- Creates pressure gradient and air from area of higher pressure in thoratic cavity moves to atmosphere an area with lower pressure.
- As a result air is pushed out the lungs into the atmosphere.
- During exercise the intercostal muscles contract further to force a larger amount of air out of the lungs to get rid of more carbon dioxide
Order of passage of oxygen after inspiration?
Trachea - bronchi - bronchioles - alveoli
Features of trachea and bronchi?
- They are different sizes
- They both have thick walls
- Both supported by cartilage in C-shaped rings. Though less in bronchi. C-shaped rings prevent collapse during low air pressure and allow the oesophagus to function alongside the trachea.
Features of Mucus?
- Traps pathogens
- Lined along epithelial tissues in airways
- Produces by goblet cells
- Cleared along tract by ciliated epithelium cells.
What’s a smooth muscle?
A muscle you cant manually control. In case for respiration it restricts air flow.
Elastic fibres?
Recoil as smooth muscle relaxes helping airway and alveoli to widen.
What does glandular tissue do?
Secretes mucus
Features of bronchioles?
- More narrow than bronchi
- Walls of smooth muscle and elastic fibres
- Larger bronchioles have some cartilage.
Where’s the site of gas exchange?
Alveoli