Revision of topic 3 Flashcards
(27 cards)
what is the relationship between surface area and volume?
- size of organism increases, volume increases faster than SA
- low SA:V ratio
- simple diffusion would take too long
Relationship of SA:V for small organisms
- small volume, large SA
- high SA:V
- simple diffusion is adequate for change
relationship between metabolic rate and smaller organisms?
- have a higher metabolic rate per unit of body mass
what is exchanged during specialised gas exchange?
- O2
- CO2
- glucose, amino acids, nutrients
- urea
why is membrane usually thin?
- for a short diffusion distance
example of thin membrane?
- alveolar membrane
example of large SA:V ratio adaptation?
- microvilli
examples of adaptations for specialised exchange surfaces?
- thin membranes for short diffusion pathways
- large SA:V
- selectively permeable
- maintaining conc gradient
explain gas exchange in fish?
- gill filaments = gill lamellae at right angles to filaments
- counter current = blood and water flow in opposite directions, oxygen diffusion gradient maintained over whole length of lamella so more oxygen diffusion
explain gas exchange in single celled organisms?
- small
- large SA:V ratio
- diffusion adequate for gas exchange
gas exchange in plants?
- compromise between gas exchange and water loss
- waterproof coverings to reduce water loss = waxy cuticle
- stomata and guard cells
- air spaces increase SA for exchange = spongy mesophyll
adaptations of xerophytes?
- hairy or rolled up leaves
- stomata in pits
what are the structures of the human gas exchange system and pathway taken?
- trachea
- bronchi
- bronchioles
- alveoli
adaptations of the alveoli?
- thin walls
- highly branched
- large SA
- RBCS slow and flatten against wall of capillary
- steep conc gradient
processes in ventilation?
- inspiration
- expiration
what happens during inspiration?
- intercostal muscles contract
- ribs move up and out
- diaphragm flattens and so that volume in diaphragm increases and pressure decreases, drawing atmospheric air into lungs
what happens during expiration?
- intercostal muscles contract
- ribs move down and inward
- diaphragm moves up and so volume decreases and pressure increases forcing air out of lungs
mass transport in animals?
- circulatory system
describe the heart and blood vessels?
- capillaries = one cell thick , tissue fluid
- valves
- atria and ventricles
- veins
- arteries
describe veins
- contain valves
- carry deoxygenated blood towards the heart at low pressure
- thin walls
- thick lumen = less resistance to blood flow
- mainly fibrous tissue
describe arteries
- no valves
- carry oxygenated blood away from the heart
- thick walls
- thin lumen to maintain pressure
describe capilaries
- connect arteries and veins together and allow exchange of materials between blood and cell
- only one cell thick
- blood in close contact with tissue allowing diffusion of materials
how is high pressure maintained in circulatory system
- constricting and recoiling of elastic and muscular walls or arteries
where is the pressure lost in circulatory system
- the capillaries
