Gas Exchange in Humans Flashcards
Explain the functions of the human gas exchange system
To allow a large volume of oxygen and carbon dioxide to be exchanged between the blood and the environment. The gases are needed and produced by respiration
Explain why mammals have to absorb large volumes of oxygen and release large volumes of carbon dioxide
- They are large and have a large volume of living cells.
- They have a high metabolic rate and respiratory rate
Describe the trachea
flexible airway supported by cartilage to prevent collapse
walls contain muscle and are lined with ciliated epithelium and goblet cells
Describe the bronchi
two divisions in trachea leading to a lung each
produce mucus to trap dirt particles and cilia to move the mucus
Describe bronchioles
branching subdivisions of bronchi
muscle in walls to control air flow in and out of alveoli
Describe alveoli
air sacs 200 micrometres in diameter at the end of the bronchioles.
collagen and elastic fibres between alveoli.
alveoli lined with epithelium.
the elastic fibres allow the alveoli to stretch and recoil
List (in order) the structures that air passes through on its journey into the lungs
- lungs
- trachea
- bronchi
- bronchioles
- alveoli
What happens when the external intercostal muscles contract?
the contraction leads to inspiration, it causes the ribs to move up and outwards
Describe the process of inspiration
- External intercostal muscles contract, internal intercostal muscles relax
- the ribs move up and outwards, increasing the volume of the thorax
- the diaphragm contracts and flattens, increasing the volume of the thorax
- the pressure in the lungs is reduced
- atmospheric pressure is greater (than inside the lungs) so air is forced into the lungs
Describe the process of expiration
- internal intercostal contract, external intercostal relax
- ribs move down and in
- volume of thorax decreases
- pressure increases
- air moves out, moving down pressure gradient
Why do organisms need oxygen?
acts as final electron acceptor in aerobic respiration which allows energy to be released in the form of ATP
Give 2 reasons why the lungs are located inside the body
- air is not dense enough to support these structures
- the body would lose a great deal of water and dry out
What is the purpose of cartilage in the trachea?
to prevent the tube from collapsing when air pressure falls
How do cells lining the trachea protect the alveoli from damage?
- cells produce mucus
- traps dirt, mucus is moved up by cilia
- if dirt/bacteria entered alveoli, could damage them/cause infection
Which type of inter-costal muscle CONTRACTS to allow for EXPIRATION?
internal
Which type of inter-costal muscle CONTRACTS to allow for EXPIRATION?
internal
How do thin walls in the alveoli allow for rapid diffusion?
short diffusion distance/pathway
What are 4 features of the alveoli that make them efficient for gas exchange?
- thin walls
- many of them contained within the lungs
- covered in lots of capillaries
- pulmonary capillaries are very narrow
What is emphysema?
damage to the walls of alveoli, caused by smoking or air pollution. This reduce the surface area for gas exchange
What 3 factors impact the rate of gas exchange in lung conditions?
- decreased surface area
- decrease concentration gradient
- increased diffusion distance
What is vital capacity?
maximum amount of air that can be exhaled and inhaled in a single breath
What is vital capacity?
maximum volume of air that can be inhaled or exhaled in a single breath
What is tidal volume?
the volume of air we breathe in and out at each breath at rest
Why would death of alveolar cells lead to impacted gas exchange?
- increased diffusion distance
- reduced surface area
- less gas exchange
How would reduced tidal volume impact CO2 in blood?
- less CO2 breathed out
- smaller concentration gradient
- less CO2 moves out of blood
