mammalian gas exchange Flashcards
What are the key features of the lungs as a gas exchange surface in mammals? (4)
Large surface area due to many alveoli
Short diffusion distance between alveoli and blood
Alveoli have a thin fluid layer to dissolve respiratory gases
Highly developed circulatory system.
What is the pathway of air through the mammalian gaseous exchange system? (2)
Air enters through the trachea, which splits into bronchi, each leading to a lung
The bronchi branch into bronchioles, which end in alveoli (site of gas exchange)
What is the role of goblet cells in the gaseous exchange system? (2)
Secrete mucus to trap bacteria and dust
Reducing the risk of infection
What is the role of ciliated epithelium in the gaseous exchange system? (2)
Moves mucus towards the throat
Preventing lung infections
What is the function of elastic fibres in the lungs? (2)
Stretch during inhalation and recoil during exhalation
Controlling airflow
What is the role of smooth muscle in the lungs? (2)
Controls the diameter of airways by contracting or relaxing
Making airflow easier during exercise
What is the function of cartilage rings in the trachea and bronchi? (2)
Support the trachea and bronchi
Preventing collapse during breathing
What happens during inspiration in mammals? (4)
- External intercostal muscles and diaphragm contract
- Causing the ribcage to move up and out
- Increasing the thorax volume and decreasing lung pressure
- Air flows into the lungs (inspiration is an active process)
What happens during expiration in mammals? (4)
- External intercostal muscles and diaphragm relax
- Ribcage moves down and in
- Decreasing thorax volume and increasing lung pressure
- Air is forced out of the lungs (normal expiration is a passive process)
What happens during forced expiration? (2)
The internal intercostal muscles contract
Forcing air out (this process is not passive)
What is tidal volume? (1)
The volume of air taken in with each breath
What is vital capacity? (1)
The maximum volume of air that can be breathed in or out
What is breathing rate? (1)
The number of breaths taken per minute
What is oxygen consumption/uptake? (1)
The rate at which an organism uses up oxygen
What is a spirometer? (2)
Device used to investigate breathing
By measuring the movement of an oxygen-filled chamber with a movable lid
How does a spirometer work? (2)
- As the person breathes in and out, the lid moves up and down
- The movements are recorded to create a spirometry trace
Why does the total volume of gas in the spirometer chamber decrease over time? (4)
Exhaled air contains carbon dioxide
Which is absorbed by soda lime
Leaving only oxygen in the chamber
As the oxygen is used for respiration, the total volume decreases
