9 Gas exchange Flashcards
How is surface area to volume ratio calculated?
surface area to volume ratio= surface area/ volume
What is mass transport?
the movement of substances over large distances to and from a gas exchange surface, when an organism is too large to rely on diffusion alone
What is used to measure the volumes of air involved in gas exchange?
manometers
How is pulmonary ventilation rate (PVR) calculated?
PVR= tidal volume x breathing rate
Describe the human gas exchange system
- trachea branches into bronchi to lungs
- bronchi continue to branch into bronchioles
- bronchioles terminate as alveoli, where gas exchange takes place with blood
Describe what happens when a human inhales
- external intercostal muscles contract, move ribs up
- diaphragm contracts, flattens
- pressure in thoracic cavity decreases
- volume of lungs increases
- movement of air into lungs
How do alveoli maximise gas exchange?
- very large surface area
- moist to aid diffusion gases
- rich blood supply to maintain concentration gradient
- short diffusion distance between alveoli and red blood cells in capillaries
What are the general effects of lung disease on gas exchange?
- reduced flow of air into lungs due to constriction of trachea and bronchi
- reduced gas exchange due to decreased surface area of alveoli
What is tissue fluid?
fluid surrounding cells in multicellular organisms
What is a concentration gradient?
difference between concentration of a substance in a space; larger gradient= faster diffusion
How does the mesophyll contribute during gas exchange in leaves?
- differentiated into column palisade cells
- large, moist surfaces (absorb oxygen and CO2), facilitating diffusion
- air spaces between cells
How does the stomata contribute during gas exchange in leaves?
- allow gases to pass in and out of pores in leaf surface
- gases diffuse due to concentration gradient between inside and outside
- can close to reduce water loss
What is the name of plants that grow in dry habitats?
xerophytes
What are the adaptations of xerophytes?
- thicker cuticle
- reduced leaf surface area
- fewer stomata
- rolled leaves
How do single-celled organisms exchange substances like oxygen and carbon dioxide?
diffusion across their cell membranes
Where in the insect tracheal system does gas exchange take place?
between the tracheole tips and body cells via diffusion
What are the adaptations of gills to maximise gas exchange?
- large surface area of lamellae
- rich blood supply gills
- concentration gradient of oxygen along whole length of lamellae by countercurrent principle
How does the countercurrent system maximise gas exchange in fish?
- instead of blood and water running in parallel, countercurrent system moves water over gills in opposite direction to blood flow
- this maintains diffusion gradients for oxygen and CO2 exchange
Gas exchange in insects:
Many insects have _______ along their thorax.
Spiracles have ______ to allow air in and out by __________.
many insects have spiracles along their thorax.
spiracles have valves to allow air in and out by diffusion.
