3. Gas Exchange in Humans Flashcards
Define Gas exchange
Process of taking gases in that are needed for life processes and getting rue of waste gases
Oxygen into blood for respiration
Co2 out made my respiring cells
Name the 8 components of gas exchange system
Trachea Bronchi Lung Bronchioles Alveoli Ribcage Intercostal muscles Diagram
What is the pathway of air into body ?
Air enters trachea
Splits into 2 bronchi 1 in each lung.
Bronchioles which then end in alveoli.
Ribcage/ intercostal muscles and diaphragm all work together to move air in and out
Where does gas exchange occur in mammals ?
Alveoli
Location of intercostal muscles
Between ribs
Interlaced intercostal muscle
External intercostal muscles
Define ventilation
Inspiration - breathing in
Expiration - breathing out
Controlled by ribcage/ Internal&external intercostal muscles and ribcage
Inspiration
External intercostal muscles and diaphragm contract.
Ribcage moves up and out.
Diaphragm falters - increasing volume of thoracic activity.
This causes lung pressure to decrease below atmospheric pressure.
As air flows down pressure gradient from high to low pressure air flows into trachea and lungs
Is inspiration active / passive
Active
Atp needed
Expiration
External intercostal muscles and diaphragm muscles relax.
Ribcage down and in
Diaphragm curves up again
Volume of thoracic cavity decreases causing air to increase above atmospheric pressure.
Air forced down pressure gradient out of lungs
Normal expiration
Passive
No energy
Forced expiration
Blowing out candles
External intercostal mucked relax and internal intercostal muscles contract pulling ribcage further down and in
Antagonistic pairs
Alveoli location
Gas exchange system
Millions of them
Microscopic
In lung
Surrounded by capillary network
What causes the change in lung pressure?
Movement of ribcage and diaphragm
Alveoli structure
Wall made from single layer of thin / flat cells called alveolar epithelium
Walls contain protein called elastin - helps alveoli Return ( recoil ) to Normal shape after inhaling & exhailing I
What are the walls of capillary made from ?
Capillary endothelium
Movement of co2 and o2
Both by diffusion and down pressure gradient
Co2 moves down its own diffusion and pressure gradient in opposite direction to oxygen - breathed out
How does o2 get into the blood
O2 diffuses out of alveoli across the alveolar epithelium and the capillary endothelium into compound called haemoglobin in blood
Where does the pressure gradient start and stop
Trachea
Bronchi
Bronchioles
Alveoli
Where does diffusion gradient start and stop
Alveoli
Alveolar epithelium
Capillary endothelium
Blood
What features for the alveoli have that speed up diffusion
Thin exchange surface - alveolar epithelium only 1 cell thick. So short diffusion pathway
Large surface area - millions of alveoli so for gas exchange
Steep conc gradient of oxygen and carbon dioxide between alveoli and capillaries which increases diffusion
