Human Gas Exchange Flashcards
Name the parts of the human gas exchange system
lungs trachea bronchi bronchioles alveoli
Why are large volumes of gas needed?
Relatively large organism (large number of cells)
maintain a high body temp. due to high metabolic and respiratory rate.
Why is the human gas exchange inside the body?
air not dense enough to support and protect this delicate structure
body would lose a great deal of water and dry out
Describe the lungs
pair of lobed structure made up of bronchioles and alveoli
supported by the ribcage
ventilated by tidal stream of air
Describe the trachea
flexible airway supported by rings of cartilage (prevents collapse and pressure drops when breathing in)
wall = ciliated epithelium and goblet cells
Describe the bronchi
1=bronchus
produces mucus to trap dirt particles
has cilia
supported by cartilage, the smaller the bronchi gets the less cartilage
Describe the bronchioles
walls=muscle lined with epithelial cells so they can contact to control airflow in/out of the alveoli
Describe the alveoli
minute air sacs
between them is collagen and elastic fibre ( allows stretch) lined with epithelium
diameter 100nm-300um
at the end of the bronchioles
the alveolar membrane is the gas exchange surface
What is breathing also known as?
breathing is also known as ventilation
What causes the pressure changes in the lungs?
the movement of the muscles:
the diaphragm
the intercostal muscles
Where are the intercostal muscles?
between the ribs
Where is the diaphragm?
separates the thorax from the abdomen
Describe the process of Inspiration/inhalation
external intercostal muscles contract
internal intercostal muscles relax
ribs move upwards and outwards which increases the volume of the thorax
Diaphragm contacts and further increases the volume of the thorax
increased volume = reduction in pressure in the lungs
atmospheric pressure > pulmonary pressure
air forced into the lungs
Describe the process of expiration/exhalation?
external intercostal muscles relax
internal intercostal muscles contract
ribs move inwards and downwards which decreases the volume of the thorax
diaphragm relaxes and further decreases the volume of the thorax
decreased volume = increase in pressure in the lungs
pulmonary pressure >atmospheric pressure
air forced out of the lungs
Is expiration active?
No it is mostly passive
the recoil of elastic tissue causes the expel of air
What is the equation for the pulmonary ventilation rate?
WITH UNITS
tidal volume x breathing rate = pulmonary vent. rate
dm3 min-1
Where is the site of gas exchange in the lungs?
epithelium of the alveoli
How is the alveoli adapted for gas exchange?
single layer of epithelial cells= short dif. pathway
good blood network supply
distance between air and red blood cell
alveoli and capillaries have a large SA: VOL
Sharp diffusion gradient = breathing (ventilation) and heart (circulation)
How are capillaries adapted for gas exchange?
capillaries have a large SA: VOL
blood capillaries are one cell thick as well
blood cells are slowed in pulmonary artery= more time 4 diffusion
blood flattened against capillary wall= reduced distance between air and red blood cell
What are the risk factors for lung disease?
smoking genetic makeup air pollution infection occupation
Define vital capacity
total vol. of air in the lungs at the end of a maximal inhalation
Define residual volume
volume of gas remaining in the lungs after the end of maximal exhalation
Define tidal volume
volume of air inspired when at rest
