Organisms Exchange Substances With Their Environment Flashcards
What is the relationship between the size of an organism and the surface area to volume ratio?
The larger an organism is, the lower the surface area to volume ratio will be
Describe the surface area to volume ratio in smaller organisms
-smaller organisms such as amoeba
larger surface area compared to volume meaning big surface area for exchange of substances , and smaller distance from outside of the organisms to the middle of it
- v small organisms can simply exchange substances across their surface without any adaptations needed
Describe the surface area to volume ratio in larger organisms
- larger organisms will typically have a higher metablolic rate which demands the efficient transport systems waste out of cells and reactants into cells. To do this they have adaptions to help material exchange across surfaces more efficient.
What are some adaptions that increase surface area to volume ratio
Villi and microvilli in small intestine - help in absorption of digested food
Alveoli and bronchioles in mammals - gas exchange
Spiracles and tracheoles in insects - gas exchange
Gill filaments and lamellae in fish - gas exchange
Thin wide leaves in plants - gas exchange
Many capillaries for mass transport - capillary network
What is breathing
Movement of air in and out of lungs
What is respiration
Chemical reaction to release energy in the form of ATP
What is gas exchange
Diffusion if oxygen from the air in the alveoli into the blood and of carbon dioxide from the blood into the air in alveoli
Explain ventilation during inspiration
During inspiration, the external intercostal muscles contract and the internal intercostal muscles relax
The diaphragm relaxes and flattens
Air pressure in the lungs is low
The rib cage moves up and out increasing thoracic volume, allowing more air into the lungs
Explain ventilation during expiration
During expiration, the internal intercostal muscles contract and the external intercostal muscles relax
The diaphragm relaxes and forms an inverted U shape.
Pressure in the lungs is high
The rib cage moves down and in, decreasing thoracic volume forcing air out of lungs
What is meant by an antagonistic pair
Two muscles work together to fairs movement. One muscle contracts and the other relaxes
What is pulmonary ventilation
Volume of air moves into the lungs in a minute (dm3min-1)
How do you calculate pulmonary ventilation
Tidal volume*ventilation rate
How are we adapted for gas exchange between alveolar epithelium and blood
- Many alveoli create a large surface area for gas exchange
- Epithelium cells are very thin for a short diffusion pathway
- Each alveolus surrounded by capillary network to remove exchanged gases, maintaining concentration gradient
outline the structure of the tracheal system
Spiracles are valve like openings where oxygen and carbon dioxide enter and leave
The trachea is a network of internal tubes which have rings within them to strengthen tubes and keep them open
Tracheoles extent throughout all tissues in the insect to deliver oxygen to all respiring cells
What are the three ways of moving gases in the tracheal system
Diffusion, mass transport, osmosis
Describe diffusion in the tracheal system
When cells respire they use up oxygen and CO2 creating a concentration gradient to from tracheoles to the atmosphere
Describe mass transport in the tracheal system
Insect comtracts and relaxes their abdominal muscles to move gases on mass
Describe osmosis in the tracheal system
The ends of tracheoles are filled with water. When insects are in flight muscles start to respite anaerobically to produce lactate, lowering WP of the cells and water moves from the tracheoles into cells by osmosis. This decreases the volume in the tracheoles and cells by osmosis. This decreases the volume in the tracheoles and more air from the atmosphere is drawn in
What adaptations do terrestrial insects have for efficient diffusion
- Many tracheoles for a large surface area
- Tracheoles have thin walls and short distance between spiracles and tracheoles - short diffusion pathway
Use of oxygen and production of CO2 - steep concentration gradient
How are terrestrial insects adapted limiting water loss
- Insects have small surface area to volume ratio where water can evaporate from
- Waterproof exoskeleton
- Spiracles can open and close to reduce water loss via evaporation
What is Ficks law
diffusion rate * concentration g/ membrane thickness
How can ficks law be calculated
Surface area*difference in concentration/ length of diffusion path
Describe fish gill anatomy
4 layers of gills on both sides of the head made up of stacks of gill filament which creates a large surface area. When gosh open their mouth water rushes in and over the gills and then out through a hole in the sides of their head
How are fish adapted for efficient gas exchange
Capillary network in lamellae + very thin lamellae - short diffusion pathway
Countercurrent flow mechanism - maintains concentration gradient
Explain the countercurrent flow mechanism
Water flows over the gills in opposite direction the the blood flow. It ensures that an equilibrium is not reached . No equilibrium ensures that a diffusion gradient is maintained across the entire length of the gill lamellae. There will always be a high concentration of water than blood, keeping that concentration gradient
Describe what happens at the stomata during gas exchange in leaves
Oxygen diffuses out of the stomata and CO2 diffuses in through the stomata. To reduce water loss, the stomata close during dark times when photosynthesis doesn’t occur
Thick cuticle?
Less water can escape as there is a longer diffusion pathway for water to evaporate out of e.g. holly
Rolling up of leaves?
Moisture is trapped and the region becomes saturated with water vapour meaning it has a high WP. There is no WP gradient between inside and outside of leaf so there is no water loss e.g. marram plants
Hairy leaves ?
Hairs trap moisture on the leaf surface. WP gradient between inside and outside of leaf is reduced meaning less water is lost via evaporation
Sunken stomata in pits or grooves ?
Traps moisture nest to the leaf and reduces the water potential gradient. E.g. pine trees
Reduced surface area to volume ratio of the leaves?
Reduced surface area to volume ratio means a slower rate of diffusion. For plants, having leaves that are small and roughly circular in cross section rather than being broad and flat, the rate of water loss can be reduced
Describe how carbohydrates are broken down (hydrolysed) in digestion
Begins in the mouth, continues in the duodenum and completed in the ileum. Amylase produced in he pancreas and salivary glands hydrolyses polysaccharides into the disaccharide maltose by hydrolysing glycosidic bonds. Sucrose and lactase are membrane bound enzymes that hydrolyse sucrose and lactose into monosaccharides.
Describe how proteins are broken down (hydrolysed) during digestion
Protein digestion starts in the stomach, continues in the duodenum and fully digested in the ileum. They can be hydrolysed by 3 enzymes
Endopeptidases hydrolyse peptide bonds between amino acids in the middle of a polymer chain
Exopeptidases hydrolyse peptide bonds between amino acids at the end of a polymer chain
Membrane bound dipeptidases hydrolyse between to amino acids
Describe the breaking down ( hydrolysis) of lipids in digestion
Lipids are digested by lipase and bile salts.
Lipase is produced in the pancreas and can hydrolyse the ester bond in triglycerides to form monoglycerides and fatty acids.
Bike salts produced in the liver can emulsify lipids to form tiny droplets called micelles. This increases the surface area for lipase to act on
What are the two types of lipid digestion
Chemical lipid digestion
Physical lipid digestion
What happens in physical lipid digestion?
Large food is broken down into smaller pieces by the means of structures such as teeth. Many small droplets of lipids provide a large surface area to enable faster hydrolysis action by lipase
What happens in chemical lipid digestion
Enzyme lipase hydrolysis lipids into glycerol and fatty acids and some monoglycerides
What are micelles
Micelles are Vesicles formed of fatty acids glycerol monoglycerides and bile salts
What happens when micelles encounter the ileum epithelial cells
When micelles encounter the ileum epithelium cells, because fatty acids and monoglycerides are polar in nature, they can simply diffuse across the cell membrane to enter the cells of the epithelial cells. Once in the cell they will be modified back into triglycerides in the endoplasmic riticulum and Golgi apparatus
How are cells lining the ileum adapted for efficient absorption
Ileum wall is covered in villi which have thin walls surrounded by a network of capillaries and epithelial cells have even smaller microvilli
These help maximise absorption by increasing surface area, decreasing diffusion pathway and maintaining a concentration gradient
What is haemoglobin
Groups of proteins with a quaternary structure, they , and RBCs transport oxygen
Describe the oxyhaemoglobin dissociation curve
Oxygen is loaded in regions with a high partial pressure of oxygen and low levels of CO2 e.g alveoli
And is unloaded in regions of low partial pressure of oxygen and high levels of CO2 e.g. respiring tissues
What is cooperative binding
Haemoglobin changes shape when the first oxygen bonds, making it easier for further oxygens to bind
What is the Bohr effect
High CO2 concentration causes the oxyhaemoglobin curve to shift to the right. The affinity for oxygen decreases because the acidic CO2 changes the shape of the haemoglobin slightly
How are human foetus adapted for their environment
They have myoglobin which has a higher affinity for oxygen at the same partial pressure compared to an adult. This means they can upload oxygen faster and the oxyhaemoglobin curve shifts left
How are llamas adapted to their environment
Llamas are found in high altitudes, which are areas of low pressure. They have a higher affinity for oxygen at lower partial pressures meaning they can still upload oxygen despite being in a low partial pressure environment and the oxyhaemoglobin curve shifts left
How are doves adapted for their environment
They have a faster metabolism so they need more oxygen for respiration to provide energy for contracting muscles. They have a lower affinity for oxygen meaning they won’t upload oxygen faster but will more readily unload oxygen which is needed for respiration
Oxyhaemoglobin cure shifts to the left
How are earthworms adapted for their environment
Are underground where there is a lower partial pressure or oxygen. They have higher affinities for oxygen even at low partial pressures so they can load with with what ever oxygen is available
Describe the circulatory system in mammals
Closed = blood remains within blood vessels
Double circulatory = blood passes though the heart twice in each circuit. One side delivers blood to the lungs and the other delivers blood to the rest of the body
What is cardiac muscle
Thick muscle layer in walls of the heart
What are the properties of cardiac muscle
Myogenic meaning it can contract and relax without nervous or hormonal stimulation
Never fatigues as long as there is an oxygen supply
What causes myocardial infarction
The blockage of coronary arteries, as cardiac muscle won’t receive oxygen therefore won’t be able to respite and the cells will die
Structure of atria
Thinner walls as they don’t need to contract as hard as they are only pumping blood to ventricles
Elastic walls to stretch when blood enters
Structure of ventricles
Muscular walls to enable bigger contraction. This creates high blood pressure to enable blood to flow longer distances like the lungs and rest of the body
Difference between left and right ventricle?
RV pumps blood into lungs at a lower pressure to prevent damage to the capillaries in the lungs and so blood flows slowly to allow time for gas exchange. Thus have thinner walls than LV
LV pumps blood to body at a high prsssure to ensure blood reaches all cells in the body. Much em thicker wall than RV to enable larger muscle contractions to create high pressure
Describe motion of valves
Prevents backflow of blood by opening when pressure is higher behind the valve and close when pressure is higher in front of the valve
Function of septum
Separates oxygenated and deoxygenated blood to maintain high concentration of oxygenated blood and maintain a concentration gradient to enable diffusion at respiring cels
Function or arteries
Carry blood away from heart
Function of arterioles
Connect to arteries to capillaries
Function of capillaries
Connect arterioles to veins
They form capillary beds, which are many branched capillaries, at exchange surfaces. They all have a narrow diameter for slow blood flow. RBC can only just fit through and are squashed against the walls which maximises diffusion
Properties of arteries
Thick muscular layer for construction and dilation
Thick elastic layer to maintain blood pressure. Walls stretch and recoil in response to heart beat
Thick muscular wall to prevent vessels bursting from high pressure
No valves
Properties of arterioles
Thicker muscle layer than arteries to restrict blood flow into capillaries
Thinner elastic layer than arteries as blood pressure is lower
Thin wall as pressure is lower
No valves
Properties of veins
Thin muscle layer so it can’t control blood flow
Thin elastic layer as pressure is much lower than in arteries
Thin wall as pressure is lower meaning there is a low risk of bursting
Contains pocket valves to prevent backflow of blood
Properties of capillaries
No muscle layer
No elastic layer
Wall is one cell thick providing a short diffusion pathway for exchange of materials between blood and cells
No valves
What happens during diastole
Atria and ventricular muscles relaxed. This is when blood enters atria via vena cava and pulmonary vein
Blood flowing into atria increases pressure within atria
What happens during atrial systole
Atria muscular walls contract increasing pressure further. Causes av valves to open and blood flows into ventricles. Ventricular muscles are relaxed
What happens during ventricular systole
Ventricle muscular walls contract increasing pressure beyond that of atria
Causing an valves to close and semilunar valves to open.
Blood is pushed out of the ventricles into the arteries (pulmonary and aorta)
What is tissue fluid
Fluid containing water glucose amino acids fatty acids ions and oxygen which bathes the tissues
