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6.4 Gas Exchange
Our lungs work with our ________ and ___________ to ensure that body cells are
well supplied with _________ and are able to give up _________________.
Oxygen is needed for aerobic cellular respiration and the production of ATP
Ventilation
The process of __________ the lungs with air and then ____________ the air.
The purpose of which is to allow _____________ of gasses in the lungs.
The site of this diffusion, within the lung are small sacs called ______________.
Oxygen in the alveoli diffuses into the ______________, while CO2 in the
bloodstream diffuses into the __________.
Mechanism of Ventilation
The tissue that makes up our lungs is not _______________ so the lungs are not
capable of _________________ movement.
The mechanism is based on the ____________ relationship between
______________ and volume.
The lungs are located in a cavity called the ___________ or thoracic cavity.
_______________ differences between this cavity and the outside are the cause
of air movement.
Inspiration (Breathing In)
The bottom of the thoracic cavity is a muscle called the _______________.
The ribs are covered with the external and internal ______________ muscles.
When the diaphragm and external intercostals contract, it ____________ the
volume of the cavity, which makes the pressure in the cavity and the lungs
________.
The pressure in the lungs is now lower (a vacuum) than the outside of the body,
so air rushes in to equalize the pressure.
Expiration (Breathing Out)
The diaphragm and intercostal muscles _________.
The volume of the cavity gets ____________, raising the pressure.
The pressure is now greater than the outside air.
Air moves ________ to equalize pressure.
Gas Exchange in the Alveoli
Air first enters your __________ or nasal passages.
Then it enters your _____________.
Then the left and right ___________.
Then smaller and smaller branches of bronchi
Then very small _______________.
Then it enters small ________ in the lung called alveoli
Alveoli structure
Alveoli are found in _____________ at the ends off the bronchioles
There are approximately _________________ in each lung.
They are surrounded by ______________.
Blood entering these capillaries is coming from the _____________ of the heart
via the ________________ arteries.
Carbon dioxide diffuses out of the blood into the alveoli and oxygen diffuses from
the alveoli into the blood.
Only a ____________ trip due to alveoli and capillary each being one cell thick
Pneumocytes
The single cell layer of the alveoli is made of two different types of cells called
pneumocytes.
Type 1 pneumocytes – very ________ with a _________ surface area for
diffusion. If damaged, these cells are ___________ of mitosis for replacement.
Type 2 pneumocytes – ________ shaped, not good for diffusion but secrete a
solution that acts as a _____________. Keeps the alveoli from sticking closed.
Can undergo mitosis to make both types of cells
Emphysema
A disease where the ____________ are destroyed.
Leading cause is tobacco smoking
One of the diseases collectively called ___________, chronic obstructive
pulmonary disease.
Chronic (slow) disease that turns alveoli into large, irregular structures with holes
in them.
______________ the surface area for diffusion, causing shortness of breath.
Other causes include: Marijuana smoke, smog, coal dust.
Lung Cancer
Begins in the lungs but is very prone to spreading (__________________).
Common sites of spreading include brain, bones, liver and __________________.
Caused by carcinogenic substances that cause the lungs cell to ____________.
Most common source of carcinogens is cigarette smoke, but other substances like
_____________ can also cause cancer.
Early diagnosis is vital due to high ________________.
Cancer Rates
Recent data supports a direct ______________ between countries that have
decreased the number of people who smoke and a decrease in lung cancer. And
vice versa