Gas Exchange (Humans) Flashcards
Describe how air moves through the respiratory system
- air enters the body and is warmed as it travels to the mouth and nose and enters the trachea
- the trachea divides into two bronchi, one bronchus to each lung, each bronchus branches out into smaller tubes called bronchioles, where air travels through
- the air enters the alveoli, where gas exchange takes place
there is a high concentration of oxygen in the alveoli and a low concentration of oxygen in the blood, so oxygen diffuses from the alveoli into the bloow
What are the parts of the thorax?
- trachea
- bronchi
- bronchioles
- alveoli
Structure of the trachea (cartilage, goblet cells, smooth muscles, cilia)
- lots of cartilage in the walls
- inner layer (epithelium) is made of goblet cells and ciliated epithelium
- contains smooth muscle
- little cilia
Structure of the bronchus (cartilage, goblet cells, smooth muscles, cilia)
- lots of cartilage in the walls
- inner layer (epithelium) is made of goblet cells and ciliated epithelium
- contains smooth muscles
- little cilia
Structure of the large bronchioles (cartilage, goblet cells, smooth muscles, cilia)
- no cartilage
- no goblet cells
- little smooth muscle
- little cilia
Structure of the alveolus (cartilage, goblet cells, smooth muscles, cilia)
- little cartilage
- no goblet cells
- little smooth muscles
- no cilia
What are goblet cells?
mucus producing cells
What is a cilia?
little hairs, to get rid of mucus
What happens when breathing in?
- intercoastal and diaphragm muscles contract
- ribcage moves upwards and downwards
- diaphragm moves downwards and becomes flatter
- air pressure decreases below the pressure in the atmosphere
- volume (thorax) increases
- pressure (thorax) decreases
- so air is drawn in
What happens when breathing out?
- intercoastal and diaphragm muscles relax
- ribcage moves downwards and inwards
- diaphragm moves upwards and becomes more dome-shape
- air pressure rises above the pressure in the atmosphere
- volume (thorax) decreases
- pressure (thorax) increases
- so air is pushed out
Why are the alveoli good for gas exchange?
- large surface area = allow more CO2 to diffuse out and more O2 to diffuse in
- good blood supply = maintains the concentration gradient
- one-cell thick walls = provides a short diffusion distance
- moist = for gases to dissolve
- permeable = so gases can diffuse easily
What does the ribs do?
protect the lungs
What do the pleural membranes do?
airtight seal and lubrication
What do the intercoastal muscles do?
- moves ribs for ventilation/breathing
How do the alveoli carry out gas exchange?
- they are millions of air sacs
- blood passing by has just returned from the rest of the body, so has a lot of CO2 and very little O2
- oxygen diffuses out of the alveolus (high conc.) into the blood (low conc.)
- carbon dioxide diffuses out of the blood (high conc.) into the alveolus (low conc.) to be breathed out
- when blood reaches body cells, oxygen is released from the red blood cells (high conc.) and diffuses into the body cells (low conc.)
- and also CO2 diffuses out of the boy cells (high conc.) into the blood (low conc.) and carried back to the lungs
