Unit 3 - Organisms Exchange substances with their environment Flashcards
How have organisms developed to cope with SA difficulties
A flattened shape so no cell is far from the surface
Specialised exchange surfaces with large areas to increase SA volume ratio
Feature of specialised exchange surfaces
Large SA relative to volume of the organism with increases rate of exchange
Very thin so that the diffusion distance is short and materials cross rapidly
Selectively permeable to allow materials across
Movement of environmental medium to maintain diffusion gradient
describe insect respiratory system
Spiracles lead into trachea which lead into tracheoles
Two methods of movement for gases in insects
Diffusion
Ventilation
Process in insects during anaerobic respiration
High anaerobic respiratory rate- Lactate moves builds in the muscles
-Reducing the water potential gradient
- Water moves into cells by osmosis
- No longer any water in tracheoles
-Lower diffusion distance for respiratory gases- so higher rate of aerobic respiration
Features of gills in fish
- They have lots of small lamellae which means they have large SA: Vol ratio
- The lamella have lots of blood capillaries and a thin surface layer of cells decreasing diffusion distance
- Blood flows in the opposite direction to water flow to maintain a high concentration across the whole lamellae
Adaptations of Dicot leaves
- Broad thin leaf- Large SA with a short diffusion distance
- Spongy mesophyll has lots of space- allowing gases to get in and out easily
- Many small stomata so never far from one to allow gases in and out faster
- Spongy Mesophyll have a large SA:Vol Ratio
Xerophitic plant modifications
- Stomata sunken in pits
- Presence of hairs creates local humidity
- Stomata on underside of leaf
- Stomata close to midrib
-Stomata close together - Thick waxy cuticle
- Thick short leaves
Why are the lungs located in the body
- Air is not dense enough to support and protect these structures
The body would lose lots of water and dry out
Alveolar epithelium adaptations
- Red blood cells are slowed
-Alveoli press against cappilaries - Thin flattened membranes
- Blood flow maintains conc gradient
- Blood cells flattened against cappilary walls
Inspiration
-External intercostal muscles and diaphragm contract
- Ribs are pulled upwards and outwards increasing volume of thorax
- The increased volume causes a reduction in pressure lower then atmospheric pressure
- Air moves into lungs along the pressure gradient
Expiration
- The internal intercostal muscles contract
- The ribs move downwards and inwards
- Diaphragm moves upwards
- This decreases volume in thorax and increases pressure in thorax
- Air is pushed out
What is the equation for PVR?
Tidal volume* Breathing Rate
How does pulmonary tuberculosis affect breathing?
Tubercules form to contain pathogen
Infected tissue forms scars (fibrosis)
This affects SA and tidal volume
Ventilation rate increases to compensate
How does fibrosis affect breathing?
Scar tissue formed in lungs from asbestos/ dust
Lungs become thicker and less elastic
Lungs arent able to expand and larger diffusion distance for gases
Increased ventilation rate to compensate
How Athsma happens
Airways inflamed and irritated
Smooth muscle in bronchiles contract and mucus is produced
Air flow and FEV reduced
Emphysema
Foreign particles trapped in alveoli
Inflammation- attracts phagocytes
Lots of elastin breaks it down- alveoli cant recoil
Decreases- SA:Vol ratio
Dissociation curve- When pO2 is high
Haemoglobin has a high affinity for oxygen
Will readily combine/ hold on to oxygen
Thus a high saturation
Dissociation curve- When pO2 is low
- Low affinity to O2 releases oxygen rather than combining
- Low saturation of oxygen
Bohr effect
When cells respire ppO2 decreases
ppCo2 increases
This increases the rate of oxygen unloading
Thus shifting the curve to the right