Flashcards in Chapter 6- Gas Exhange Deck (21)
In humans where does gas exchange take place?
In small air sacs called alveoli inside the lungs
How does gas exchange happen between air in the alveoli and blood flowing in adjacent capillaries?
By diffusion- there is a concentration gradient - air in alveolus is higher conc of oxygen and a Lower concentration of carbon dioxide then the blood in the capillary- this process is called ventilation
What are type I pneumocytes?
Are extremely thin alveolar cells that are adapted to carry out gas exchange
What do the walls of each alveolus consist of?
A single layer of cells called the epithelium - most cells in there are type I pneumocytes - walls of adjacent capillaries are very close- adaption which increases the rate of gas exchange
What type II pneumocytes?
Secret a solution containing surfactant that creates a moist surface inside alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension - helps prevent collapse of the lungs
What is the route of air entering lungs?
1) Air enters through nose or mouth
2) Passes down the trachea
3) Trachea divers to form two bronchi, one bronchus leads to each lung
4) Inside lungs bronchi divides repeatedly to form a tree like stitcher of narrower airways called bronchioles
5) End of bronchioles are groups of alveoli where gas exchange takes place
What do muscle contractions cause?
The pressure to change inside the thorax that forces air in and out of the lungs to ventilate them
What is inspiration and expiration?
1) muscle contractions cause pressure inside thorax to drop below atmospheric pressure- causes air to be drawn into lungs until pressure has risen to atmospheric pressure
2) muscle contractions then cause pressure inside the thorax to rise above atmospheric , so air is forced out from the lungs to the atmosphere
What are the 2 states muscles can be in?
Contracting and relaxing
What happens to muscle when it contracts
Do work when they are contracted- become shorter
What happens to muscles when they relax
Lengthen- don't do any work
What happens in an antagonistic pair of muscles?
And one muscle contacts the other second muscle relaxes - inspiration and expiration are examples
Explain diaphragm as example of antagonistic pairs
Inspiration: moves downwards and flattens
Expiration: moves upwards and becomes more domed
Explain rib age as example of antagonistic pairs
Inspiration: moves upwards and outward
Expiration: Moves downward and inwards
Explain boiling and pressure change as example of antagonistic pairs
Inspiration: volume in thorax increases and pressure decreases
Expiration: volume inside thorax decreases and pressure increases
Explain movement of diaphragm as example of antagonistic pairs
Diaphragm- contracts and moves downwards so pushes abdomen wall out
Abdomen wall- relaxes, allowing pressure from diaphragm to push it out
Diaphragm - diaphragm relaxes, so it can be pushed upwards to domed shape
Abdomen wall- contract pushing abdominal organs and diaphragm upwards
Explain movement of ribcage as example of antagonistic pairs
External intercostal muscles- contract, pulling ribcage up and outward
Internal intercostal muscles - relax, and are pulled back into their elongated state
External intercostal muscles- relax and are pulled back into elongated state
Internal intercostal muscles- contract, pulling ribcage a inwards and downwards
Causes of lung cancer
2) passive smoking
3) air pollution
4) radon gases- (radioactive gases)
Consequences of lung cancer
Difficulties with breathing
Coughing up blood
Loss of appetite
Causes of emphysema
Smaller air sacs with much thicker walls
Total surface area is very reduced
Gas exchange is less effective
1) phagocytes inside alveoli