Gas Exchange Flashcards
Can you describe the relationship between the size of an organism or structure and its surface area to volume ratio?
As size increases surface area to volume decreases
What things need to be transferred between an organism and its environment?
Respiratory Gases
heat
Nutrients
Excretory Products
How is surface area to volume ratio calculated? Compare a 1cm3 and 6cm3 cube.
Surface area/ volume
Ratio of 1: 6:1
Ratio of 6: 3:1
What are features of specialised exchange surfaces?
Large surface area
Large concentration gradients
Maintaining high conc grads
Thin exchange surface, permeable
What is fick’s law?
Diffusion rate is proportional to SAx conc grad/ thickness of surface
How do single celled organisms exchange substances?
Simple diffusion of respiratory gases down established concentration gradient from respiration, short diffusion distance.
What is the relationship between surface area to volume ratio and metabolic rate?
As surface area:volume decreases metabolic rate increases.
How are insects adapted for efficient gas exchange?
Oxygen travels down spiracles through trachae which are supported by rings of chitin.
Spiracle valves open and close to prevent evaporation.
Trachae divides into tracheoles which deliver gases directly to bodily tissues.
Explain countercurrent flow and parallel flow:
Countercurrent flow: respiratory gases do not reach equilibrium, allows diffusion along the entire length of the gill plate, concentration gradient is maintained across the lamellae.
Parallel flow: systems reach equilibrium and no further exchange takes place, so diffusion gradient for 50% of the gill.
What three ways to respiratory gases move in and out of the tracheal system?
Diffusion gradient
Mass transport due to abdominal contractions.
Ends filled with water osmosis in when lactic acid produced allows oxygen in for respiration.
How do insects reduce water loss?
Waterproof coating (exoskeleton, waterproof cuticle)
Small Surface area:volume to minimise diffusion.
How are fish adapted for efficient gas exchange?
4 gills
water enters fish mouth, buccal floor lowers.
Water passes across gill filaments
many gill filaments with many gill lamellae for a large surface area.
Thin epithelium for short diffusion distance.
Water leaves gill opening.
Describe how the stomata open and close and explain why this happens:
Open:
Sunlight causes AT of K+ in
lowers WP of cell and osmosis in through aquaporins
vacuole volume increases becomes turgid and stoma opens.
Closed: Stop AT of K+, diffusion of K+ out, increases WP osmosis out, vacuole volume decreases, becomes flaccid and stoma closes.
How are plants adapted for efficient gas exchange?
Flat leaves increase surface area
Stomata allow air in and out and prevents evaporation
Air spaces in leaf short diff dist between mesophyll and air.
What adaptations do xerophytic plants have to try and limit water loss?
Hairs- trap moist air
thick Waxy cuticle- reduce water loss
Small leaves- lower surface area
sunken stomata- traps layer of moist air
rolled leaves- traps layer of moist air
less stomata- less water loss
shiny cuticle- reflect light
Thick stems- store water
Spines- lower surface area
Large root systems- maximise water uptake
Densely packed mesophyll- less transpiration
Can you give functions of the human gas exchange system?
Many alveoli- increase surface area
Many capillaries- increase surface area more diffusion
Thin alveoli/capillary - short diffusion distance
Ventilation/circulation- maintain conc grad
Elastic recoil- expels co2
Trachae cartilage- prevent collapse
What is the difference between correlation and causation?
Correlation: link between two factors may not be causal
Causation: one factor directly impacting another factor
How do you calculate pulmonary ventilation rate?
Amount of air exchanged in one breathing cycle.
Breaths per min x tidal volume
What is ventilation?
Breathing in and out in response to changes in pressure and thoracic volume
To maintain conc grad of gases in alevoli
Can you describe what happens during ventilation?
Breathing in:
External intercostals contract
Internal intercostals relax
ribs up and out
vol of thorax increases
diaphragm contracts and flattens
decreases thoracic pressure
negative pressure allows air to move in and down pressure gradient.
Breathing out:
External intercostals relax
Internal intercostals contract
ribs down and in
vol of thorax decreases
diaphragm relaxes and returns to U
increases thoracic pressure
positive pressure allows air to move out and down pressure gradient.
Could you interpret information relating to the effects of lung disease on gas exchange and/or ventilation? E.g. Pulmonary fibrosis is a lung disease that causes the epithelium of the lungs to become irreversibly thickened and leads to reduced elasticity of the lungs. Suggest what symptoms would arise and why.
Decreases lung volume
Decreases tidal volume
Increases diff distance
Decreases efficiency of gas exchange
What are some risk factors for lung disease?
Smoking
Asbestos
Fungal spores
Pollution
Leads to COPD
Chronic obstructive pulmonary disorder
