Human Gas Exchange System Flashcards
(28 cards)
When does human gas exchange occur?
Lungs
What is the trachea?
The entrance to the human gas exchange system. A flexible airway
What provides protection to the front of the trachea?
Ridges of cartilage that prevent the trachea collapsing as air pressure falls when breathing in
Why is there no cartilage at the back of the trachea?
So that the oesophagus isn’t constricted
What does the trachea divide into?
Two bronchi
What are the bronchi made of?
Cartilage and smooth muscle
What does each bronchus divide into?
Bronchioles
What do the bronchioles divide into?
Small air sacs - alveoli
What do alveoli fill with when you breath in?
Oxygen
How do the alveoli improve gas exchange?
Provide a large surface area for gas exchange (there are millions of alveoli in the lungs)
Why do mammals require such a large volume of oxygen?
1) they are relatively large organisms with a large volume of cells
2) they maintain a high body temperature which is related to having high metabolic and respiratory rates
Why are mammalian lungs located inside the body?
Air is not dense enough to support and protect them
The body would lose a lot of water
What is ventilation controlled by?
The rib cage, intercostal muscles and diaphragm
What supports and protects the lungs?
The rib cage
Where are cilia located?
Inside the bronchus and trachea.
What’s the function of cilia?
To move dirt-laden mucus to the throat
How are the alveoli adapted for efficient gas exchange?
Each alveolus is surrounded by a network of capillaries which provide a large surface area for gas exchange between the alveoli and the blood stream and a short diffusion pathway
Alveoli are lined with a single layer of epithelial cells which provides short diffusion distance
How is the concentration gradient maintained during gas exchange?
The quick transport of gases in the bloodstream maintains a steep concentration gradient of oxygen and carbon dioxide
What is ventilation?
Breathing
What is inspiration?
Breathing oxygen in
What is expiration
Breathing air out
What’s the process of inspiration?
EXTERNAL INTERCOSTAL muscles CONTRACT, internal intercostal muscles relax
RIBS are pulled UPWARDS and OUTWARDS, increasing volume of thorax
DIAPHRAGM muscles CONTRACT, causing it to flatten, increasing volume of the thorax
increased volume of thorax means LESS PRESSURE in lungs
ATMOSPHERIC pressure is GREATER than PULMONARY pressure so air is forced into the lungs
Process of expiration
INTERNAL INTERCOSTAL muscles CONTRACT whilst external intercostal muscles relax
RIBS move DOWNWARDS and INWARDS, decreasing volume of thorax
DIAPHRAGM muscles relax so are pushed up by the abdomen. Volume of thorax is further reduced
decreased volume of thorax INCREASES PRESSURE in LUNGS
PULMONARY pressure is greater than ATMOSPHERIC PRESSURE so air is forced out of the lungs
How are lungs adapted for efficient gas exchange?
Each alveolus is surrounded by a network of capillaries which provide a large surface area for gas exchange between the alveoli and the blood stream and a short diffusion pathway
Alveoli are lined with a single layer of epithelial cells which provides short diffusion distance
red blood cells are slowed as they pass through PULMONARY capillaries - allows time for diffusion
steep concentration gradient is maintained by ventilation
blood flow through PULMONARY capillaries maintains conc grad
