Exchange- Gas Exchange in Humans Flashcards
Why is breathing/ventilation important?
Humans need to get oxygen into the blood for respiration and they need to get rid of carbon dioxide which is made by the respiring cells
What is the role of the trachea?
As you breathe in, air enters the trachea
What are the bronchi?
The trachea splits into two bronchi, and each bronchus leads to each lung
What are the bronchioles?
Smaller tubes branched off each bronchus
What are alveoli?
Small air sacs where gases are exchanged (bronchioles end here)
What three things work together to move air in and out?
The ribcage, intercostal muscles and diaphragm
What happens to the external and internal intercostal muscles during inspiration?
External contract, internal relax
What happens to the ribcage during inspiration?
Moves upwards and outwards
What happens to the diaphragm during inspiration?
Contracts and flattens which increases the volume of the thoracic cavity
What happens to lung pressure during inspiration?
Decreases to below atmospheric pressure as the volume of the thoracic cavity increases
What way will air move during inspiration?
From an area of higher pressure to an area of lower pressure (down a pressure gradient) so air flows down the trachea and into the lungs
What type of process is inspiration?
Active as it requires energy
What is the process of inspiration?
- External intercostal muscles contract, internal intercostal muscles relax, diaphragm contracts
- Causes ribcage to move upwards and outwards and diaphragm to flatten, increasing volume of the thoracic cavity
- As volume of thoracic cavity increases, lung pressure decreases to below atmospheric pressure
- Air moves down a pressure gradient so air flows down trachea into lungs
- Active process, requires energy
What happens to the external and internal intercostal muscles during expiration?
External relax, internal contract
What happens to the ribcage during expiration?
Moves downwards and inwards
What happens to the diaphragm during expiration?
Relaxes and becomes curved again
What happens to the volume of the thoracic cavity in expiration?
Decreases which causes air pressure to increase to above atmospheric pressure
Which way does air move during expiration?
Forced down the pressure gradient and out of lungs
What type of process is expiration?
Passive as it doesn’t require energy
What is the process of expiration?
- External intercostal muscles relax, internal intercostal muscles contract, diaphragm relaxes
- Ribcage moves downwards and inwards, diaphragm becomes curved again
- Volume of thoracic cavity decreases, air pressure increases to above atmospheric pressure
- Air forced down pressure gradient and out of lungs
- Passive process- doesn’t require energy
How many alveoli do lungs contain?
Millions
What is each alveolus made from?
A single layer of thin, flat cells called alveolar epithelium
How do alveoli help gas exchange?
They increase the surface area
What are the alveoli surrounded by?
A network of capillaries
