Gaseous Exchange Flashcards
Give examples of materials that need to be interchanged between an organism and its environment.
- Respiratory gases (oxygen and carbon dioxide)
- Heat
- Nutrients
- Excretory products
where does the exchange take place in an organism?
Exchanges takes place at the surface of an organism, and the materials absorbed are used by the cell. The cell or cells of the organism make up its
volume.
Explain why small organisms have a high metabolic rate
Small organisms have a high metabolic rate as
they have a large surface area to volume ratio
and lose heat faster than larger organisms. They
have a high rate of respiration to maintain their
core body temperature.
What makes a good exchange surface?
Large surface area
• Large concentration gradients – associated with an efficient transport
system
• Thin exchange surface – so short diffusion pathway
• Permeable
• Moist – gases diffuse more rapidly in solution
What makes an efficient gas exchange surface in humans
In humans, the lungs are our respiratory interface with the environment.
In order to be an efficient gas exchange surface the lungs have a very small
diffusion distance and large surface area and as a result are delicate.
Therefore, the lungs would be easily damaged if the rib cage was not there to
protect them.
- What is the trachea?
Trachea (Wind pipe)
The trachea is a tube like structure that
carries air from the mouth to the lungs.
- What is the bronchi?
Bronchi
The trachea splits into two bronchi as it
enters the lungs, which allows air to travel
to the left and right lung (singular:
Bronchus)
- What is the bronchioles?
Bronchioles
The Bronchi further divide into smaller branches called bronchioles. These then
supply the alveoli with air.
- Describe the alveoli
The alveoli are small sacks at the end of the bronchioles, that act as the interface between the air in the lungs and the blood. There are many alveoli and their walls are folded to provide a large surface area. In fact, the total alveolar surface are in human adults is about 70m2.
How does the alveoli maintain a large concentration gradient between the gases in the blood and the alveoli?
The alveoli have a rich blood supply which circulates and when combined with the process of ventilation help to maintain a large concentration gradient between the gases in the blood and in the alveoli.
what is a thin squashed cell?
Thin squashed cell -
squamous
how are the gases in the alveolar air spaces separated from the blood?
The gases in the alveolar air spaces are separated from the blood by the alveolar epithelium (squamous) and the wall of the capillary.
Describe the alveolar epithelium
The alveolar epithelium is a
one cell thick layer with a
very thin diffusion distance
to optimise diffusion.
describe breathing
Breathing is a result of the difference in pressure between the air in the lungs and the
air outside the body. The pressure inside the lungs is altered by changes in lung volume
Describe the process of inhalation.
external intercostal muscles contract Internal intercostal muscles relax Rib cage moves outwards Diaphragm contracts and moves down Lung volume increases Pressure in lungs less than outside Air moves into lungs
Describe the process of Exhalation.
External intercostal muscles relax Internal intercostal muscles contract Rib cage moves inwards Diaphragm relaxes and moves up Lung volume decreases Pressure in lungs greater than outside Air forced out of lungs
Give the equation for pulmonary ventilation
PVR = Tidal volume x breathing rate
give the definition of pulmonary ventilation
Pulmonary ventilation (sometimes called minute ventilation) is the amount of air exchanged in one breathing cycle
Give the definition of tidal volume
the volume of air exchanged on one breath
Explain how the pulmonary ventilation can be changed
The pulmonary ventilation can be changed by altering either, the ventilation rate, the tidal volume, or both.
define inspiratory/exploratory reserve volume
Inspiratory/Expiratory reserve – Extra volume required for a deep breath
define residual volume
Residual Volume – Air that remains in lungs to prevent collapse of alveoli.
define vital capacity
Vital capacity - is the maximum amount of air a person can expel from the lungs
what lung disease causes damage to and scarring of the lung epithelium which results in the
deposition of fibrous tissue in the lung epithelium
Fibrosis
name the two effects of fibrosis
- Reduces the rate of diffusion (longer diffusion pathway and less
permeable) - Reduces the elasticity of the lung therefore breathing out is not as
efficient
