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
Arteries properties
Blood from heart
Thick muscular walls
Folded endothelium
Run into arterioles
i
i
Veins
Take blood back to the heart
Thin muscular walls
Large lumen
Valves stop backflow
Aided by contraction of muscles
Capillaries
-Where exchange occurs
intertwined within tissue
One cell thick walls
large network- increases SA:VOL
Tissue fluid
Fluid surrounds cells in tissues
Comprises of small molecules able to leave the blood
Formation of the tissue fluid (Process)
Hydrostatic pressure in the cappilaries forces water into the surrounding area at the arteriole end
This causes a decreased water potential in the venule end as the concerntration of ions has increased
Water re-enters the cappilaries at the venule end by osmosis
Any excess tissue fluid is transported via the lymphatic system into the ciruclatory system.
Step 1- Atrial systole
Ventricles relaxed and atria contract
Increases pressure in atria, forcing blood into the ventricles
AV valves forced open
When pressure increases in ventricles- AV valves forced shut
Step 2-Ventricular systole
Ventricles contract
Increases pressure in ventricles relative to atria
AV valves forced shut
Semi lunar valves open
Step 3- Diastole
All muscles relax
Pressure in pulmonary artery and aorta is greater than ventricles so SL valves shut
AV valves open
Arethroma formation
Damage is caused to endothelium (e.g by blood pressure)
White blood cells and lipids clump under lining
This builds up an arethroma over time (Plaque)
Arethromas can lead to
Aneurysms Swelling in vessel
Thrombosis- Clot
Myocardial infarction- Death of heart muscle cells
Risk factors for cardiovascular disease
High colesterol/ poor diet
Cigarette smoking
High blood pressure
What does the xylem transport?
Mineral ions and water
What does the phloem transport?
Sugars and organic substances
Transpiration process
Water evaporates from the leaves at the top of the xylem
Water diffuses out of spongy mesophyll cells into the airspace
This causes water to exit from xylem to surrounding cells by osmosis
Due to cohesion water is pulled with the gradient towards the leaf
Water enters the root by osmosis as the water concerntration gradient increases
Factors affecting transpiration rate
Light
Temperature
Humidity
Wind
Potometer experiment
Cut shoot underwater at a slant- to prevent air from entering xylem and at a slant to increase SA.
Assemble potometer underwater
Check apparatus is air and watertight
Dry leaves and allow potometer to acclimatise
Record starting position of air bubble
Rectod time and distance moved
Translocation process
Active transport is used to actively load solutes from companion cells into the sieve tubes of the phloem at the source
This lowers water potential inside the sieve tubes, so water enters the tubes by osmosis
Creating a higer hydrostatic pressure
At the sink end, solutes diffuse into the companion cells as they’re being used
Decreases the water potential in cells so water leaves seive tubes by osmosis
Lowers pressure at the sink
Results in a pressure gradient from source to sink. Solution moves down hydrostatic pressure gradient.
Digestion of carbs
Amylase breaks down starch into maltose in saliva and pancreas
Once starch is hydrolysed, it is broken down by enzymes in the ileum.
Digestion of lipids
Bile salts in the liver emulsify the lipids
Lipase made in the pancreas hydrolyses the lipids in the small intestine
Digestion of proteins
Endopeptidases and exopeptidases both break peptide bonds between amino acids sequencially.
Where are endopeptidases found?
Synthesised in the pancreas and secreted into the small intestine.
Where are exopeptidases found?
Cell surface membrane of epithelial cells in small intestine
How is each biological molecule is absorbed?
Glucose/ Galactose/ Amino acid—- cotransport
Frustose—-> Facilitated diffusion
Lipids——> simple diffusion through phospholipid bilayer
Role of micelles in absorbtion of lipids
Aid the transport of monoglycerides to the surface of the epithelial cells
Role of bile salts
Increases the surface area of lipids that bile salts can work on- emulsification
Why are arterioles useful
They can cut off blood supply to specific organs.
E.g stomach during excercise
Three adaptations of tracheoles
Thin walls- Short diffusion distance
Large network- Large SA to vol ratio
Fluid in end of tracheoles which moves out during anaerobic respiration- increasing rate of diffusion
Role of micelles
Role of Aorta recoiling
Smooths blood flow
Describe and explain effect of increasing PPCO2 on dissociation of oxyhaemoglobin
Decreases haemoglobins affinity to O2
By decreasing blood PH
