Gas exchange (humans) Flashcards
Describe the structure of the thorax.
The thorax includes the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli, and pleural membranes
What is the function of the ribcage?
The ribcage protects internal organs, such as the lungs.
What are intercostal muscles, and what is their function?
Intercostal muscles are muscles between the ribs that control their movement, aiding in inhalation and exhalation
Explain the role of the diaphragm in ventilation
The diaphragm is a muscular dome at the bottom of the thorax that changes pressure to control inhalation and exhalation
What is the trachea, and what is its function?
The trachea, or windpipe, is where air enters the thorax and flows to the lungs.
Describe the structure and function of bronchi
Bronchi are large tubes branching off the trachea, with one bronchus for each lung, to carry air to the lungs
What are bronchioles, and how are they related to the alveoli?
Bronchioles are smaller tubes formed by the splitting of bronchi in the lungs, connected to the alveoli
Explain the structure and function of alveoli
Alveoli are tiny air sacs where gas exchange takes place
What is the pleural cavity, and what is its function?
The pleural cavity is found on the outside of the lungs and inside of the chest cavity, lubricating the lungs to reduce friction during breathing.
Describe the features of the lungs that make gas exchange efficient.
- Large surface area
- Only one cell thick
- Excellent blood supply/large capillary network
Explain what happens in the lungs for the process of inhalation to occur
- Intercostal muscles contract
- Ribs move up and out
- Diaphragm contracts/flattens
- The volume inside the thorax increases
- Pressure decreases
- Air drawn in
Adaptations to the lungs for efficient gas exchange include:
- Many alveoli = increased surface area
- Many capillaries = increase surface area
- Constant ventilation and blood flow = maintaining the concentration gradient
- Thin walls – only 1 cell thick = shorter distance for diffusion = faster diffusion
- Moist – to allow faster diffusion
How is the alveoli adapted for gas exchange?
- Once cell thick - short diffusion distance
- Large SA - more diffusion can occur through cauliflower-like shape
- Network of capillaries to maintain concentration gradient in blood
- Moist lining on the alveolar walls - for faster diffusion of gases
- Good ventilation through constant breathing - maintains concentration gradient in lungs
Describe and explain how the lungs are adapted to allow rapid exchange of oxygen between air in the alveoli and blood in the capillaries around them. (5)
- many alveoli walls folded to provide a large SA
- Many capillaries provide a large SA
- leading to fast diffusion
- ventilation maintaining a concentration gradient leading to fast diffusion
Using ideas about diffusion explain how oxygen gets to our cells
● Oxygen in the air enters our blood via diffusion through capillaries around the alveoli
● This is because the concentration of oxygen in the blood is lower than the concentration of oxygen in the air/lungs
● Oxygen is transported around the body in the blood
● Capillaries carry blood to our cells
● Oxygen passes out of the blood across the wall of the capillary into the cells via diffusion
● This happens because the concentration of oxygen in the blood is higher than the concentration of oxygen in the cells
● Diffusion across the walls of capillaries can happen because they are very thin
What is the role of the intercostal muscles and the diaphragm in ventilation?
- The intercostal muscles and diaphragm help in the process of breathing.
- During inhalation, the intercostal muscles contract, and the diaphragm contracts downwards. During exhalation, they relax.
How does the ribcage change during inhalation and exhalation?
During inhalation, the ribcage moves up and out. During exhalation, it moves down and in.
How does smoking affect chronic bronchitis?
Smoking damages the cilia and irritates the lining of the bronchi, leading to more mucus production and a smoker’s cough.
Describe the effects of smoking on emphysema
Smoking damages the alveoli walls, reducing the surface area for gas exchange and making it difficult to carry out basic tasks due to a lack of oxygen
How does smoking affect the circulatory system?
Smoking damages the circulatory system by:
- increasing the risk of coronary heart disease.
- It also makes blood cells more sticky and narrows blood vessels, increasing the likelihood of clots
Oxygen is absorbed through the alveoli in the lungs. How are the alveoli adapted for this function?
- Alveoli have moist lining on alveolar walls for quick diffusion of gases.
- Alveoli are thin for short diffusion distance.
Give one function of the ribs
To help breathing
Explain the role of the diaphragm when a person breathes out.
- Diaphragm relaxes into a dome-shape
- whilst thorax volume decreases and thorax air pressure increases
Give two adaptations of the lungs that help the rapid absorption of oxygen into the blood
- Lots of Alveoli provide a large surface area
- Moist lining on the alveolar walls for faster diffusion of gases
