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Topic 3 - ID - Coggle Diagram
Topic 3 - ID
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Gas exchange
Humans
Key terms
Breathing - movement of air into and out of the lungs.
Ventilation - Scientific word for breathing.
Respiration - chemical reaction to release energy in the form of ATP.
Gaseous exchange - diffusion of oxygen from air in alveoli and co2 into blood.
VentilationINSPIRATION:
- External intercostal muscles contract to pull the ribs up and out.
- Internal intercostal muscles relax.
- Diaphragm contracts to move down and flatten.
- Lung volume increases.
- Air pressure drops - causes air to move in down pressure gradient.
EXPIRATION:
- External intercostal muscles relax.
- Internal intercostal muscles contract to pull the ribs down and in.
- Diaphragm relaxes to move up and dome.
- Lung volume decreases.
- Air pressure rises - forces air out due to pressure gradient.
Pulmonary Ventilation
- Total volume of air that is moved into the lungs during one minute (dm3min-1)
PV = Tidal volume x Ventilation rate
Alveolar Epithelium
Once the gases are in the alveoli, gas exchanges between the epithelium and the blood.
Alveoli are tiny air sacks, and there are 300 million in each human lung which creates a very large surface area for gas exchange.
The alveoli epithelium cells are very thin, to minimise the diffusion distance.
Each alveolus is surrounded by a network of capillaries to remove exchanged gases, and therefore maintains a concentration gradient.
Terrestrial insects
Adaptations for efficient diffusion
- Large surface area - large number of fine tracheoles.
- Short diffusion pathway - walls of tracheoles are thin and short distance between spiracles and tracheoles.
- Steep diffusion gradient - use of oxygen and production of carbon dioxide.
Tracheal system
Exoskeleton made of hard fiborous material for protection.
Lipid layer to prevent water loss.
Spiracles are round, valve like openings running along the length of the abdomen. Oxygen and carbon dioxide enter and leave via the spiracles.
Trachea are a network of internal tubes. Trachea have rings within them to strengthen and keep them open.
Tracheoles are smaller extensions of trachea. These extend throughout all the tissues in the insect and deliver oxygen to respiring cells.
Method of Moving gases in the tracheal system
- Diffusion - when cells respire they use up oxygen and produce carbon dioxide, creating a concentration gradient within the atmosphere.
- Contracts and relaxes abdominal muscles to move gases on mass.
- Osmosis - when insects are in flight their muscles respire anaerobically to produce lactate. This lowers the water potential of cells. water moves from tracheoles into the cells lowering air pressure. Forces air in from the atmosphere.
Limiting water lossWater evaporates off the surface of terrestrial insects, and the adaptations of exchange surfaces provides ideal conditions for evaporation.ADAPTATIONS TO PREVENT LOSS:
- Small surface area to volume ratio where water can evaporate from.
- Waterproof exoskeleton.
- Spiracles can open and close to reduce water loss.
Fish
Gas exchange in fishFish are waterproof and have a small surface area to volume ratio.
- Require a gas exchange surface in the gills.
Fish obtain oxygen from water, they have adaptations to maintain the concentration gradient to enable diffusion to occur.
Gas exchange surface features
- Large surface area to volume ratio.
- Short diffusion distance.
- Maintained a concentration gradient.
DIFFUSION EQUATION:Diffusion Rate - (surface area x difference in concentration)/ length of diffusion path
Fish Gill Anatomy
There are four layers of gills on both sides of the head.
The gills are made of stacks of gill filaments.
Each gill filament is covered in gill lamellae, position at right angles to filament.
This creates a large surface area.
When fish open their mouth, water rushes in and over the gills and then out through a hole in the sides of their head.
Adaptations
- Large surface to volume ratio - created by many gill filaments covered in many gill lamellae.
- Short diffusion distance - due to capillary network in every lamellae and very thin gill lamellae.
- Maintaining concentration gradient - counter-current flow mechanism.
Counter current exchange Principle
Water flows in opposite direction to the blood in the capillaries.
Countercurrent flow ensures that equillibrium is not reached.
Ensures that diffusion gradient is maintained across the entire length of the gill lamellae.
Plants
Gas Exchange at a stomata
Oxygen diffuses out of the stomata.
Carbon dioxide diffuses in through the stomata.
To reduce water loss by evaporation, stomata close at night when photosynthesis wouldn't be occuring.
NORMAL LEAVES = "Dicotyledonous"
XerophytesPlants that are adapted to survive in environments with limited water.ADAPTATIONS:
- Curled Leaves to trap moisture to increase humidity.
- Hairs to trap moisture to increase local humidity.
- Sunken stomata to trap moisture to increase local humidity.
- Thicker cuticle to reduce evaporation.
- Longer root network - reach more water.
Haemoglobin
Basic Structure
- Haemoglobins are groups of proteins found in different organisms.
- Haemoglobin is a protein with a Quaternary structure.
- Haemoglobin and red blood cells transport oxygen.
Oxygen dissociation curve
- Oxygen is loaded in regions with a high partial pressure of oxygen (e.g alveoli).
- Oxygen is unloaded in regions of low partial pressure (e.g respiring tissues).
S-SHAPED CURVE
Cooperative bindingThe cooperative nature of oxygen binding to haemoglobin is due to the haemoglobin changes shape when the first oxygen binds.
- Makes it easier for other oxygens to bind.
The Bohr effectThe Bohr effect is when a high carbon dioxide concentration causes the oxyhaemoglobin to shift to the right.
The affinity for oxygen decreases because the acidic carbon dioxide changes the shape of the haemoglobin slightly.
- Low Partial Pressure of carbon dioxide in the alveoli. Curve shifts left, increased affinity and therefore UPLOADS more oxygen.
- High Partial Pressure of carbon dioxide at respiring tissues. Curve shifts to the right, decreased affinity and therefore UNLOADS more oxygen
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Digestion & absorption
Adaptations
During digestion, large molecules are Hydrolysed into smaller molecules that can be absorbed across cell membranes.
Digestion in Mammals
CarbohydratesCarbohydrates require more than one enzyme to hydrolyse them into monosaccharides:
- Amylases
- Membrane-bound dissachridases
Amylase is produced by the pancreas and salivary glands. It hydrolyses polysaccharides into the dissachride maltose by hydrolysing the glycosidic bonds.Sucrase, Lactase & Maltase are membrane bound enzymes that hydrolyse sucrose, lactose and maltose into monosaccharides.
ProteinsProteins are a large polymer that can be hydrolysed by 3 enzymes:1. Endopeptidases - hydrolyse peptide bonds between amino acids in the middle of the polymer.
- Exopeptidases - hydrolyse peptide bonds between amino acids at the end of polymer chain.
- Membrane-bound dipeptidases -hydrolyse peptide bonds between two amino acids.
Protein digestion starts in stomach, continues I the duodenum (First part of small intestine) and is fully digested in the ileum.
Lipids
Lipids are digested by lipase and the action of bile salts.
CHEMICAL
Lipase is produced in the pancreas and it can hydrolyse the ester bond in tryglycerides to form the monoglycerides and fatty acids.
PHYSICAL
Bile salts are produced in the liver and can emulsify lipids to form tiny droplets, micelles (vesicles formed of fatty acids, glycerol, monoglycerides and bile salts).
This increases the surface area for lipase to act on.
Absorption
In mammals the products of digestion are absorbed across the cells lining in the ileum.
The ileum wall is covered in villi, which have thin walls surrounded by a network of capillaries and epithelial cells have even smaller microvilli.
These features maximise absorption by increasing the surface area, decreasing the diffusion distance and maintaining a concentration gradient.
Lipid absorptionLipids are digested into monoglycerides and fatty acids by the action of lipase and bile salts.These form tiny structures called micelles.
- Simple diffusion across the cell membrane - when the micelles encounter the ileum epithelial cells, due to the non-polar nature of the fatty acids and monoglycerides they can .
- Modification back into triglycerides - inside of the endoplasmic reticulum.
- Formation of chylomicrons inside the Golgi apparatus - Fatty globules (triglycerides) combine with proteins.
- Chylomicrons are released from the epithelial cells - through exocytosis and enter a lacteal (lymph capillary).
- Chylomicrons travel away from the intestine - via Lymph in the Lacteal.
Monosaccharide and amino acid absorption
To absorb glucose and amino acids from the lumen to the gut there must be a higher concentration in the lumen compared to the epithelial cells.
BUT:
There is usually more in the epithelial cells.
That is why active transport and co-transport is required.
Tissue Fluid
How is it formedWHAT IS FORCED OUT
- Water molecules
- Dissolved minerals and salts
- Glucose
- Small proteins and amino acids
- Fatty acids
- Oxygen
WHAT REMAINS
- Red blood cells
- Platelets
- Larger proteins
How is it reabsorbed?
Large molecules remain in the capillaries and therefore create a lowered water potential.
Towards the venule end of the capillaries, the hydrostatic pressure is lowered due to loss of liquid, but the water potential is very low.
Water re-enters the capillaries by osmosis.
Lymph
Not all the liquid will be reabsorbed by osmosis, as equillibrium will be reached.
The rest of the tissue fluid is absorbed into the lymphatic system and eventually drains back into the bloodstream near the heart.
Circulatory system
Double circulatory systemDEFINITIONS:
- Closed = the blood remains within the blood vessels.
Double = blood passes through the heart twice.
Mammals require a double circulatory system to manage the pressure of blood flow.
- The blood flows through the lungs at a lower pressure.
- Prevents damage to capillaries in the alveoli.
- Reduces speed of blood flow, enabling more time for gas exchange.
- The oxygenated blood from the lungs then goes back through the heart to be pumped out at a higher pressure.
- Important to ensure the blood reaches the respiring cells.
Key Blood VesselsThere are many blood vessels within the circulatory system:
- Coronary arteries and other blood vessels are attached to these organs:
- Heart (vena cava, aorta, pulmonary artery & pulmonary vein).
- Lungs (pulmonary artery & pulmonary vein).
- Kidneys (Renal artery & Vein)
Major blood vessels are connected via arteries, arterioles, capillaries & veins:
- Arteries - carry blood away from the heart.
- Arterioles - smaller than arteries.
- Capillaries - connect arterioles to veins.
- Veins - carry blood back to the heart.
Differences between Veins and arteries
Muscle wall thicker in arteries so that constriction and dilation can occur.
Elastic layer thicker in arteries to maintain blood pressure. The walls can stretch and recoil in response to heart beat.
Walls thicker in arteries to prevent bursting under high blood pressure.
Valves only in Veins - to prevent backflow.
CapillariesForm capillary beds at exchange surfaces, which are branched capillaries.
- Narrow diameter - to slow blood flow.
- Red blood cells only just fit and are squashed which maximises diffusion.
Arterioles
Thicker muscular layer than arteries to help restrict blood flow into the capillaries.
Thinner elastic layer and thickness of wall - pressure is lower.
Cardiac MuscleThe walls of the heart have a thick muscular layer.This muscle is called cardiac muscle and it has unique properties:
- Myogenic - meaning it can contract & relax without nervous or hormonal stimulation.
- Never fatigues - as long as it has oxygen supply.
Coronary arteriesSupply the cardiac muscle with oxygenated blood.These branch off from the aorta.If they become blocked cardiac muscle won't receive oxygen, therefore will not be able to respire and the cells will die.
- This results in myocardial infraction (heart attack).
Structure
- 2 Atria
- Thinner muscular walls.
- Do not need to contract hard.
- Elastic walls to stretch when blood enters.
- 2 Ventricles
- Thicker muscular walls to enable bigger contraction.
- Creates a higher blood pressure to enable blood to flow longer.
RIGHT VENTRICLE:
- Pumps blood to the lungs. This needs to be a lower pressure to prevent damage to capillaries in the lungs and so blood flows slowly to allow time for gas exchange.
- Thinner muscular wall.
LEFT VENTRICLE:
- Pumps blood to the body. This needs to be a higher pressure to ensure blood reaches all the cells in the body.
- Much thicker muscular wall to create higher pressure.
VALVES:
- Semi-Lunar - In aorta and pulmonary artery.
- Atrioventricular valves - Between atria & ventricles.
- Open when pressure is higher behind the valve.
SEPTUM:
- Seperates the deoxygenated and oxygenated blood.
- Maintains high concentration of oxygen.
Cardiac cycleDIASTOLE:
- The atria and ventricular muscles are relaxed.
- This is when blood will enter the atria via the vena cava and pulmonary vein.
- The blood flowing into the atria increases the pressure within the atria.
ATRIAL SYSTOLE:
- The atria muscular walls contract, increasing the pressure further.
- This causes the atrioventricular valves to open and blood to flow into the ventricles.
- The ventricular muscular walls are relaxed.
VENTRICULAR SYSTOLE:
- After a short delay, the ventricle muscular walls contract, increasing the pressure beyond that of the atria.
- Causes the atrioventricular valve to close and semi-lunar valve to open.
- Blood pushed out of the ventricles into the arteries.
Cardiac Output
The volume of the blood which leaves one ventricle in one minute is the cardiac output:
Cardiac output = heart rate x stroke volume
Heart rate = Beats of the heart per min
Stroke volume = Volume of blood that leaves the heart each beat dm3
Mass transport in Plants
Transpiration
Factors that affect transpirationLIGHT
- Positive correlation.
- More light causes more stomata to open = larger surface area for evaporation.
TEMPERATURE
- Positive correlation
- More heat means more kinetic energy, faster moving molecules and therefore more evaporation.
HUMIDITY
- Negative correlation
- More water vapour in the air will make the water potential and more positive outside the leaf, therefore reduces the water potential gradient.
WIND
- Positive correlation
- More wind will blow away humid air containing water vapour, therefore maintaing the water potential gradient.
COHESION TENSION THEORY
- Cohesion:
- Water is dipolar molecule (slight negative oxygen & slight positive hydrogen).
- This enables hydrogen bonds to form between different water molecules.
- This creates cohesion between water molecules. Therefore water travles up the xylem as a continuous column.
- Capillarity
- Tension of water is when water sticks to other molecules - adheres to xylem walls.
- The narrower the zylem the bigger the impact of tension.
- Root pressure
- As water moves into the roots via osmosis it increases the volume of the liquid inside the root and therefore the pressure increases in root.
- This increase in pressure in the roots forces water upwards.
Movement of water up the xylem
- Water vapour evaporates out of stomata - this loss in water volume creates a lower pressure.
- Water is pulled up xylem - when water is lost, pressure deficit forces movement (negative pressure).
- Hydrogen bonds creates cohesion between water molecules - this creates a column of water within the xylem.
- Water molecules adhere to walls - this helps to pull the water column upwards.
- Tension is created as column of water is pulled up the xylem - pulling the xylem in to become narrower.
Translocation
Phloem tissue
- Sieve Tube elements
- Living cells.
- Contain no nucleus
- Contain few organelles
- Companion cells
- Provide ATP for active transport of organic substances
Connected via plasmodesmata allows cytoplasm to be shared.
PROCESS
TRANSLOCATION 1
- Organic substances in leaves (sucrose) - from photosynthesis occurring in chloroplasts of leaves.
- Facilitated diffusion of sucrose into companion cell - high concentration in leaf (source) and low in companion cell.
- Active transport of H+ ions from the companion cells into the spaces in the cell walls of companion cells.
- H+ move into sieve tube elements - down their concentration gradients via carrier proteins.
- Co-transport of sucrose with the H+ ions* - occurs via protein co-transporters to transport the sucrose into sieve tube elements.
TRANSLOCATION 2
- Water potential drops - increase of sucrose in the sieve tube element.
- Water element enters the sieve tube element from the surrounding xylem vessels via osmosis.
- Increases hydrostatic pressure - causing the liquid to be forced towards the sink.
TRANSLOCATION 3
- Water potential decreases - sucrose is actively transported into the sink cell.
- Osmosis of water into xylem due to lowered water potential.
- Lowers hydrostatic pressure because the volume of the sieve tube element decreases.
Movement of organic substances is due to difference in hydrostatic pressures.
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