CHAPTER 3 - EXCHANGE AND TRANSPORT SYSTEMS Flashcards
- size and surface area - gas exchange - digestion and absorption - haemoglobin - circulatory system - the heart - transport in plants, xylem and phloem
why is an exchange transport system needed
- every organism needs to take in substances and release other substances in order to survive
what affects how quickly the absorbance and release of substances takes place
- size
- surface area = SA
describe the exchange of substances with the environment
- every organism needs to exchange things with its environment
- cells needs to take in oxygen for aerobic respiration and nutrients
- need to excrete waste products like carbon dioxide and urea
- most organisms need to stay at roughly the same temperature, so heat needs to be exchanged
SA:VR relationship
- affects how quickly substances are exchanged
- smaller organisms : higher SA : VR, compared to larger organisms
exchange organs and mass transport systems
- an organism needs to supply every one of its cells with substances like glucose and oxygen for respiration
- it also needs to remove waste products from every cell, to avoid the cell damaging itself
how do single celled organisms exchange and transport substances
- substances can diffuse directly into/out of the cell, across the cell surface membrane
- diffusion rate = quick, because the distance the substance needs to travel = small
how do multi-cellular organisms exchange and transport substances
- diffusion across the outer membrane is too slow BECAUSE :
- some cells are deep within the body and there is a big distance between them and the outside environment
- AND larger animals have a low SA:VR and this means its difficult for there to be enough substances exchanged to supply a large volume of animal, through a relatively small outer surface
instead of using diffusion, how do multi-cellular organisms absorb and excrete substances
- using specialised exchange organs, ex - lungs
- need mass transport systems to carry substances to and from their individual cells
- in mammals, mass transport = the circulatory system which uses blood to carry oxygen and glucose around the body, also carries around hormones, antibodies and waste like CO2
how does mass transport work in plants
- the transport of water and solutes in the xylem and phloem
describe the process of heat exchange
- metabolic activity in the cells creates heat
- staying at the right temp is heavily influenced by size and shape
how does body size affect heat exchange
- rate of heat loss is dependent on SA
- if the organism is small, then its relative SA is large which means it loses heat easily
- smaller organisms need a relatively high metabolic rate so they can generate enough heat to stay warm
how does body shape affect heat exchange
- animals of any size with a COMPACT shape have a SMALL SA relative to V = minimised heat loss from their surface
- animals with a LESS COMPACT shape, ex - have bits that stick out, have a LARGER SA relative to their V = increased heat loss from their surface
how is the arctic dox adapted so it reduces heat loss
- small ears
- round head
- these 2 features reduce its SA : VR and therefore reduces its heat loss
how is the african bat eared fox adapted so it reduces heat loss
- large ears
- more pointed nose
- these 2 features increases its SA:VR and therefore increases its heat loss
how is the european fox adapted so it can match the temp of its environment
- aims to match the temp of its environment
name the behavioural and physiological adaptations to aid exchange for ANIMALS WITH A HIGH SA:VR
- tends to lose more water as it evaporates from their surface
- big problem especially for animals living in hot regions where water evaporates quickly
- some dessert mammals have kidney structure adaptations so that they produce less urine to compensate
name the behavioural and physiological adaptations to support the high metabolic rate of small mammals
- needed to support high metabolic rates
- small mammals living in cold regions need to eat large amounts of high energy foods like seeds and nuts
name the behavioural and physiological adaptations to maintain the internal temperature of small mammals
- may have thick layers of fur OR hibernate when the weather gets really cold
name the behavioural and physiological adaptations to cool down large organisms
- larger organisms which live in hot regions, like elephants and hippos, find it hard to keep cool as their heat loss is relatively slow
- elephants : developed large flat ears which increase their SA - allows them to lose more heat
- hippos : spend much of the day in the water - behavioural adaptation to help them lose heat
why do plants and animals have adaptations to aid gas exchange
- because they are large organisms and gas exchange isn’t easy for them due to them having a LARGE gas exchange surface
how does gas exchange take place
it occurs over a gas exchange surface
what is a gas exchange surface
a boundary between the outside environment and internal environment of an organism
what are the 2 gases that need to diffuse across the gas exchange surface as quickly as possible
- oxygen
- carbon dioxide
what are the 2 things most gas exchange surfaces have in common, which are there to increase the rate of diffusion
- have a large SA
- they are thin = one layer of epithelial cells, this provides a SHORT DIFFUSION PATHWAY across the GE surface
what else does the organism do to increase the rate of diffusion
- maintain a steep conc gradient of gases across the exchange surface
describe the process of gas exchange in single celled/unicellular organisms
- absorb and release gases by diffusion through their CELL SURFACE MEMBRANES
- have a relatively large SA, thin surface and a short diffusion pathway
- therefore, there is no need for a specialised gas exchange system
what does having a short diffusion pathway mean
it means that oxygen can take part in biochemical reactions as soon as it diffuses into the cell
describe the basis of how gas exchange works in fish
- lower conc of oxygen in water than in air
- fish have special adaptations to get enough oxygen
what is the gas exchange surface for fish
the gills
describe the structure of gills
- water, which contains oxygen, enters the fish through its mouth and passes through the gills
- each gill is made of lots of thin plates called GILL FILLAMENTS
- gill fillaments have a large SA for exchange of gases = increases the rate of diffusion
- gill fillaments are covered in lots of tiny structures called LAMELLAE = increases the SA even more
- lamellae have lots of blood capillaries and a thin layer of cells = speeds up diffusion of oxygen between water -> blood
describe the counter-current system
- takes place in the gills of a fish = GAS EXCHANGE SURFACE
- blood flows through the lamellae in one direction, and water flows over them in the OPPOSITE direction = counter current system
- CC system means that the water with a relatively HIGH oxygen conc ALWAYS flows next to blood with a LOWER conc of oxygen
- a steep conc gradient maintained between the water and blood = ensures as much as oxygen possible diffuses from water -> oxygen
how does gas exchange take place in dicotyledonous plants take place
- plants need CO2 for photosynthesis, this produced O2 as a WASTE GAS
- the O2 produced as a waste gas is needed for RESPIRATION
- main gas exchange surface = surface of MESOPHYLL CELLS in the leaf
- have a large SA = well adapted
- the mesophyll cells are inside the leaf
- gases move in and out through pores in the epidermis
- these pores = STOMATA
- stomata can open = allow exchange of gases
- they can also close = if the plant is losing too much water
- GUARD CELLS control the opening and closing/movement of the stomata
how does gas exchange take place in insects
- terrestrial insects have microscopic air-filled pipes = TRACHEA, these are used for GE
- air moves INTO the trachea through pores on the surface
- the pores on the surface = SPIRACLES
- oxygen travels down the conc gradient, towards the CELLS
- trachea branch off into smaller TRACHEOLES
- tracheoles have thin, permeable walls and go to individual cells = means that O2 diffuses directly into the respiring cells = no transport of O2
- CO2 from cells moves down its conc gradient -> SPIRACLES = to be released into the atmosphere
- insects use rhythmic abdominal moevements to move air in and out out of the spiracles
what is the consequence of gas exchange for plants and insects
they lose water
have plants and insects evolved adaptations to reduce the extent of water loss
yes
how are insects adapted to not losing too much water
- use their muscles to close their spiracles
- have a waterproof, waxy cuticle all over their body = reduces evaporation
- have tiny hairs around their spiracles = reduces evaporation
how are plants adapted to not losing too much water
- their stomata are usually kept open during the day = allows GE
- water enters guard cells = makes them turgid = opens stomatal pore
- if the plants starts to become dehydrated, the guard cells lose water = become flaccid = closes pore
what is the name of plants that are specially adapted for life in warm, dry or windy (where water loss is a massive problem)
xerophytes
give some examples of xerophytic adaptations
- stomata is sunk in pits to trap water vapour, reduces the conc gradient of water between LEAF and AIR = reduces evaporation of water from leaf
- has a layer of ‘hairs’ on the epidermis to trap water vapour around the stomata
- curled leaves with the stomata INSIDE = windy conditions increase the rate of diffusion and evaporation
- reduced number of stomata = fewer places for water to escape
- has thicker, waxy, waterproof cuticles on leaves and stems = reduces evaporation
what is the purpose of GE for humans
- humans need O2 in their blood
- they need to get rid of CO2 = made by respiring cells
describe the structure of the GE system in humans
- inhalation
- as you breathe in, air enters the trachea
- trachea slips into 2 bronchi, each bronchus leads to each lung
- each bronchus branches off into smaller tubes = bronchioles
- bronchioles end in alveoli = small air sacs
- GE surface = alveoli
- ribcage, intercostal muscles and diaphragm all work together to move air in and out/ in the process of inhalation and exhalation
describe the role of intercostal muscles in gas exchange in humans
- found between the ribs
- 3 sets, only need to know 2 = internal intercostal muscles and external intercostal muscles
- internal intercostal muscles = inside of the external intercostal muscles
describe the basics of the process of ventilation
- consists of inspiration and expiration
- controlled by the movements of the diaphragm, internal and external intercostal muscles and ribcage
describe the process of inspiration = breathing in
- external intercostal muscles and diaphragm = contract
- ribcage = moves upwards and outwards
- diaphragm = flattens and increases in volume
- volume of thoracic cavity = increases
- lung pressure = decreases to below atmospheric pressure
- air flows from an area of higher pressure -> an area of lower pressure (down the pressure gradient)
- air flows down the trachea -> lungs
- inspiration = active process = requires energy
describe the process of expiration = breathing out
- external intercostal muscles and diaphragm = relaxes
- ribcage = moves down and in
- diaphragm = curves up, becomes dome shaped again
- volume of thoracic cavity = decreases
- air pressure = increases above atmospheric pressure
- air is forced down the pressure gradient and out the lungs
- passive process = doesn’t require energy
what is forced expiration, explain this and give an example
- expiration can be forced, ex - if you blow out candles on a birthday cake
- during forced expiration, the external intercostal muscles RELAX and internal intercostal muscles CONTRACT = pulls ribcage down and in
- movement of the internal and external intercostal muscles is antagonistic = opposing
what are the alveoli and what are their role in GE
- lungs contain millions of microscopic air sacs = alveoli = where GE occurs
- alveoli are surrounded by a network of capillaries
describe the structure of alveoli
- wall of each alveolus is made from a single layer of thin, flat cells = ALVEOLAR EPITHELIUM
- walls of capillaries = made from CAPILLARY ENDOTHELIUM
- walls of the alveoli contain a protein called ELASTIN
- elastin = elastic, helps alveoli to return/recoil to their normal shape AFTER inhaling and exhaling
describe the basics in the movement if O2 and CO2 through the GE system
- air, containing O2, moves down the trachea, bronchi, bronchioles into the alveoli = movement happens DOWN a pressure gradient
- oxygen moves into blood = can be transported around the body = happens down a diffusion gradient
- CO2 moves down its own diffusion and pressure gradients
- moves down in the OPPOSITE direction to O2 = so it can be breathed out
describe how GE takes place in the alveoli
- O2 diffuses out of the alveoli, across alveolar epithelium and capillary endothelium, into haemoglobin in the blood
- CO2 diffuses into the alveoli from the blood
summarise the complete movement of oxygen in the GE system
trachea -> bronchi -> bronchioles -> alveoli -> alveolar epithelium -> capillary endothelium -> blood
trachea -> bronchioles = pressure gradient and O2 is from the air
alveolar epithelium -> blood = diffusion gradient and O2 is in the haemoglobin
name and explain the factors which affect the rate of diffusion
- a thin exchange surface = the alveolar epithelium is only one cell thick = short diffusion pathway
- large SA = there are millions of alveoli = large SA for GE
- there is also a steep conc gradient of O2 and CO2 between the alveoli and the capillaries = increases the rate of diffusion = constantly maintained by the flow of blood and ventilation
what does lung disease effect
- ventilation
- gas exchange
give examples of lung diseases
- tuberculosis
- fibrosis
- asthma
- emphysema
what are the 4 measures of lung function
- tidal volume
- ventilation rate
- forced expiratory volume / FEV1
- forced vital capacity/ FVC
define tidal volume
- volume of air in each breath
- usually between 0.4 dm3 to 0.5 dm3
define ventilation rate
- the number of breaths per min
- healthy person should have a rate of 15 breaths per min
define forced expiratory volume/FEV1
- max volume of air which can be breathed out in 1 second
define forced vital capacity
- max volume of air it is possible to breathe forcefully out the lungs, after a very deep breath in
what is tuberculosis
- TB is a lung disease caused by bacteria
- when someone gets infected with TB bacteria, their immune system cells build a wall around the bacteria in the lungs
- forms small and hard lumps : tubercles
- infected tissue in the tubercles dies AND the gas exchange surface is damaged = tidal volume decreases
- TB causes fibrosis = further reduces the tidal volume
- low tidal volume = less air inhaled in each breath
- because tidal volume is low, patients will have to breathe faster
- common symptoms : persistent cough, coughing up blood/mucus, chest pains, shortness of breath and fatigue
what is fibrosis
- formation of scar tissue in the lungs
- could be due to result of an infection OR exposure to substances like asbestos or dust
- scar tissue = thicker and less elastic than normal lung tissue
- formation of scar tissue means the lungs are less able to expand = cant hold as much air = tidal volume reduced = FVC reduced
- reduced rate of gas exchange BECAUSE diffusion is slower across a thicker scarred membrane
- patients have a faster ventilation rate than normal so they can get enough air into their lungs, so they can oxygenate their blood
- common symptoms : shortness of breath, a dry cough, chest pain, fatigue and weakness
what is asthma
- respiratory condition where the airways become inflamed and irritated
- usually because of an allergic reaction to substances like pollen and dust
- during an asthma attack, the smooth muscle lining the bronchioles contracts and a large amount of mucus is produced
- causes constriction of the airways, making it difficult for the sufferer to breathe properly
- air flow in and out of lungs is SEVERELY reduced = less oxygen enters the alveoli and moves into the blood
- reduced air flow means FEV1 is severely reduced
- common symptoms : wheezing, tight chest, shortness of breath
- during an asthma attack the symptoms come on very suddenly
- they can be relieved by drugs, often in inhalers, which cause the muscle in the bronchioles to relax = opening up the airways
what is emphysema
- caused by smoking or long term exposure to air pollution - foreign particles in the smoke or air become trapped in the alveoli
- causes inflammation, which attracts phagocytes to the area
- phagocytes produce an enzyme that breaks down elastin, this is a protein found in the walls of the alveoli
- elastin = elastic, helps the alveoli to return to their normal shape after inhaling and exhaling air
- loss of elastin = alveoli cant recoil to expel air as well, it remains trapped in the alveoli
- leads to destruction of the alveoli walls = reduces SA of alveoli = rate of gas exchange decreases
- common symptoms : shortness of breath and wheezing
- patients have a increased ventilation rate as they try to increase the amount of air, containing O2, reaching their lungs
the effect of lung diseases on gas exchange
- TB, fibrosis, asthma and emphysema all reduce the rate of GE in the alveoli
- less O2 is able to diffuse into the blood stream = body cells receive less O2 = rate of aerobic respiration decreases = less energy released and sufferers often feel tired and weak
define a risk factor
- factors which increase someones likelihood of getting that disease
- all diseases have risk factors
- ex, smoking is a risk factor for developing lung cancer
define correlation
a link between 2 things
does correlation indicate cause
- no
- correlation does not mean that one thing causes another
- correlation is not causation
- ex, smokers have an INCREASED risk of developing cancer but that does NOT mean that smoking causes cancer
how do you carry out a dissection for a level biology
- could be a dissection of a gas exchange system or a mass transport system, or an organ in those systems, in either an animal or plant
what are dissection tools
- scalpels
- have a very sharp detachable blade
- can be used for making very fine cuts
- dissecting scissors
- used for precise cutting
- safer to use than scalpels = blades are less likely to snap under pressure
- can be easier to avoid damaging the tissue underneath when using scissors
- dissecting pins
- can be used with wax filled dissection tray to pin a specimen in place during the dissection
- tweezers
- useful for holding and manipulating the smaller parts of the specimen
- all dissecting tools should be clean, sharp and free from rust
- blunt tools dont cut well and can be dangerous
what is digestion in very simple terms
- food molecules are broken down BY ENZYMES into smaller molecules
- these molecules can be absorbed into the bloodstream
describe the basics of digestion
- large biological molecules, like starch and proteins, in food are too BIG to cross cell membranes = can’t be absorbed from the gut -> blood
- during digestion, these LARGE MOLECULES are BROKEN DOWN into SMALLER MOLECULES, like glucose and amino acids
- the smaller molecules CAN move across cell membranes
- they can be easily absorbed from the gut -> blood = allows them to be transported around the body
- aim of transport is so they can be used by the body cells
- large bio molecules = POLYMERS
- polymers -> monomers via HYDROLYSIS REACTIONS
- hydrolysis reactions break bonds through the addition of water
- carbohydrates = hydrolysed -> DISSACHARIDES -> MONOSACCHARIDES
- fats = FATTY ACIDS and MONOGLYCERIDES
- proteins -> AMINO ACIDS
describe the role of digestive enzymes
- used to break down biological molecules in food
- variety of different digestive enzymes are produced by SPECIALISED CELLS in the digestive systems of mammals
- enzymes are released to mix with food, with the aim of breaking them down
- because enzymes are specific and only work with their specific substrate, different enzymes are needed to catalyse the breakdown of different food molecules
how does amylase digest carbohydrates
- amylase : digestive enzyme which catalyses the breakdown of starch
- starch : a mixture of 2 polysaccharides, both of which are made from long chains of A glucose molecules
- amylase catalyses hydrolysis reactions which break the glycosidic bonds in starch -> produces MALTOSE (disaccharide)
where is amylase produced and released
- produced by SALIVARY GLANDS
- releases amylase into MOUTH
- produced by PANCREAS
- releases amylase into SMALL INTESTINE
describe the action of membrane bound dissacharides
- they are enzymes which are attached to the cell membranes of epithelial cells which line the ileum
- help break down disacchararides -> monosaccharides
- ^ involves hydrolysis of glycosidic bonds
what enzymes breaks down disaccharides
a disaccharidase which is complementary to the specific disaccharide
what is the disaccharide for sucrose, maltose and lactose
sucrose - sucrase
maltose - maltase
lactose - lactase
what are the monosaccharides that make up sucrose, maltose and lactose
sucrose - glucose and fructose
maltose - glucose and glucose
lactose - glucose and galactose
how are monosaccharides transported
- transported across the epithelial cell membranes in the ileum via specific transporter proteins
how are lipase enzymes involved in the digestion of lipids
- they catalyse the breakdown of lipids -> monoglycerides and fatty acids
- done through the hydrolysis of ester bonds in lipids
where are lipases made and released
- mainly made in the PANCREAS
- secreted into the SMALL INTESTINE
what is the role of bile salts in the digestion of lipids
- produced by the LIVER
- role EMULSIFYING lipids : causes lipids to form small droplets
- bile salts are NOT enzymes, but they have an important role in lipid digestion
why is it important that bile salts make a big lipid droplet -> a small lipid droplet, in terms of lipid digestion
- bile salts cause a big lipid droplet to emulsify and this leads to the formation of many smaller lipid droplets
- greatly increases the SA of the lipid available for lipases to work on
what happens to lipids in lipid digestion after lipase hydrolyses lipids
- the monoglycerides and fatty acids (produced from the breakdown of lipids) stick with BILE SALTS
- when they stick with bile salts, they form tiny structures called MICELLES
- micelles help the products of lipid digestion to be absorbed
describe the basics of the digestion of proteins
- proteins are broken down by many different peptidases
- peptidases : enzymes that catalyse the conversion of proteins -> amino acids BY hydrolysing the PEPTIDE BONDS between amino acids
describe the action of endopeptidase
- hydrolyses peptide bonds within a protein
- endo : think of IN THE, so within
name some endopeptidases and their action
- trypsin AND chymotrypsin are both ENDOpeptidases
- made in PANCREAS
- secreted/released in SMALL INTESETINE
- pepsin is an ENDOpeptidase
- released into stomach via cells in the stomach lining
- pepsin only works in ACIDIC conditions
- acidic conditions provided by hydrochloric acid in stomach
describe the action of exopeptidase
- act to hydrolyse peptide bonds at the ENDS of proteins
- remove single amino acids from proteins
- EXO : think of EXIT, so end of
describe the action of dipeptidase
- are exopeptidases
- work specifically on DIPEPTIDES
- act to separate the 2 amino acids which make up a dipeptide
- separate them by hydrolysing the PEPTIDE bond between them
- often located in the cell surface membrane of EPITHELIAL CELLS in the SMALL INTESTINE
how are monosaccharides, the product of carbohydrate digestion, absorbed
- glucose is absorbed by ACTIVE TRANSPORT with sodium ions via a co-transporter proteins
- galactose is absorbed the same way with the same co-transporter protein
- fructose is absorbed via facilitated diffusion through a different transporter protein
how are monoglycerides and fatty acids, the products of lipid digestion, absorbed
- micelles help to move monoglycerides and fatty acids
-> epithelium - micelles constantly break up and reform, so they can ‘release’ monoglycerides and fatty acids : allows them to be ABSORBED
- whole micelles are NOT taken up across the epithelium
- monoglycerides and fatty acids are LIPID SOLUBLE, so they CAN diffuse directly across the epithelial cell membrane
how are amino acids, the products of protein digestion, absorbed
- absorbed via co-transport
- sodium ions are actively transported OUT of the ileum epithelial cells -> the blood
- ^ creates a sodium ion conc gradient
- sodium ions can then diffuse from the lumen of the ileum -> epithelial cells VIA sodium dependent transporter proteins AND they carry the amino acids with them
describe the role of haemoglobin (HM)
- mass transport systems, like the circulatory system in animals ensure efficient movement of substances throughout the organism
- haemoglobin : an important part of the circulatory system
- human HM is found in red blood cells
- role is to carry oxygen around the body
- different organisms have their own type of HM
describe the structure of HM
- large protein
- has a quaternary structure
- made of 4 polypeptide chains
- each chain has ONE haem group, which contains a iron ion and gives HM its red colour
- each molecule of human HM can carry 4 oxygen molecules
describe the formation and action of oxyhaemoglobin
- happens in the lungs
- oxygen joins to HM in RBC -> forms oxyhaemoglobin
- reversible reaction
- near the body cells, oxygen leaves oxyhaemoglobin and this causes it to go back to haemoglobin
what is the name for when an oxygen molecule joins haemoglobin
ASSOSCIATION/LOADING
what is the name for when an oxygen molecule leaves haemoglobin
DISSOCIATION/UNLOADING
what is one of the factors that haemoglobin affinity for oxygen is impacted by
the partial pressure of oxygen/ pO2
what is the partial pressure of oxygen
- a measure of oxygen concentration
- the greater the conc of dissolved oxygen in cells = higher the partial pressure of oxygen
what is the effect of increasing pO2 on the affinity of HM
it increases
what is the effect of oxygen loading and unloading at a high and low pO2
- oxygen loads onto HM to form oxyhaemoglobin at a HIGH pO2
- oxygen unloads its oxygen where there’s a LOWER pO2
talk about the behaviour of HM in the alveoli in the lungs
- alveoli : in lungs
- high O2 conc
- high pO2
- high affinity
- oxygen LOADS
talk about the behaviour of HM in the respiring tissue
- respiring tissue
- low O2 conc
- low pO2
- low affinity
- oxygen UNLOADS
talk about high pO2 in dissociation curve graphs
- pO2 tends to be high in the lungs
- HM has a high affinity for O2
- HM has a high saturation of O2
talk about low pO2 in dissociation curve graphs
- pO2 tends to be low in respiring tissues
- HM has a low affinity for O2
- HM has a low saturation of O2
why is the line on a dissociation curve not straight
- is ‘S - shaped’
- due to the saturation of HM affecting affinity
how is the curve of the line on the dissociation curve graph affected by HM binding
- when HM is joined with its first O2 molecule, its shape changes in a way that makes it easier for other O2 molecules to join (cooperative binding)
- as the HM become more saturated, it becomes harder for more O2 molecules to join
- ^ because of this, the curve has a steep bit in the middle where its EASY for O2 molecules to join
- the shallow bits at the end is where O2 molecules find it harder to join
- when the curve is steep (where it is EASY for O2 molecules to join HM), a small change in pO2 can cause there to be a BIG change in the amount of O2 carried by the HM
what is pCO2
- partial pressure of carbon dioxide
- measure of the concentration of CO2 in a cell
what does pCO2 affect
oxygen unloading
how does having a high pCO2 affect oxygen dissociation
oxygen is given up more readily at a high pCO2
describe the bohr effect
- when cells respire, they produce CO2 -> raises the pCO2
- ^ increases the rate of O2 unloading (more oxyhaemoglobin -> oxygen + haemoglobin)
- causes the dissociation curve to shift to the right
- saturation of blood with O2 is lower for a given pO2, means more O2 is released
describe the different types of haemoglobin
- different organisms have different types of HM with different O2 transporting capacities
- HM depends on things like where they live, how active they are and their size
- having a certain type of HM is an adaptation that helps the organism to survive in a particular environment
how does HM change in low oxygen environments
- organisms that live in environments with a low concentration of O2 have HM HIGHER AFFINITY of O2 than human HM
- ^ this is because there isn’t much O2 available, so the HM has to be very good at loading any available O2
- dissociation curve of their HM is to the LEFT of ours
how does HM change in high activity levels
- organisms that are very active and have HIGH O2 DEMAND have HM with a LOWER AFFINITY OF O2
- ^ this is because they need their HM to EASILY UNLOAD O2, more availability for them to use
- dissociation curve of their HM is to the RIGHT of ours
give an example of an animal which has HM which is adapted to a low oxygen environment
- lugworm
- lives in burrows beneath the sand where there is a LOW O2 conc
- its HM has to be able to pick up as much O2 as possible
- HIGH affinity of O2
give an example of an animal which has HM which is adapted to a high activity level
- hawk
- high respiratory rate
- lives where there is plenty of O2
- its HM has to be able to UNLOAD O2 quickly
- because it needs to meet the HIGH O2 demand
- LOW affinity of O2
how does size affect HM
- small mammals tend to have a higher SA:V, than larger mammals
- ^ causes them to lose heat quickly, so they have a HIGH metabolic rate to help keep them warm = HIGH O2 DEMAND
- mammals smaller than humans have HM with a LOWER affinity of O2 than human HM
- ^ because they need their HM to EASILY UNLOAD to meet their HIGH O2 DEMAND
- dissociation curve of their HM is to the RIGHT of the human one
give an example of an animal and how its size leads to its HM being adapted
- a rat
- higher SA:V than a human
- its HM needs to unload O2 easily to meet the HIGHER O2 DEMAND
- LOWER affinity for O2
- dissociate curve of their HM is to the RIGHT of the human one
what is the function of the circulatory system
- multicellular organisms, like mammals, have a LOW SA:V
- ^ this means they need a specialised mass transport to carry raw materials from specialised exchange organs to their body cells : circulatory system
structure of the circulatory system
- made of the heart and blood vessels
- heart pumps blood through blood vessels (arteries, arterioles, veins and capillaries) to reach different parts of the body
where does the PULMONARY ARTERY carry blood from and carry blood to
- carries blood from the HEART
- carries blood to the LUNGS
where does the PULMONARY VEIN carry blood from and carry blood to
- carries blood from the LUNGS
- carries blood to the HEART
where does the AORTA carry blood from and carry blood to
- carries blood from the HEART
- carries blood to the BODY
where does the VENA CAVA carry blood from and carry blood to
- carries blood from the BODY
- carries blood to the HEART
where does the RENAL ARTERY carry blood from and carry blood to
- carries blood from the BODY
- carries blood to the KIDNEYS
where does the RENAL VEIN carry blood from and carry blood to
- carries blood from the KIDNEYS
- carries blood to the VENA CAVA
how does the blood transport raw materials around the body
- blood transports RESPIRATORY GASES, PRODUCTS OF DIGESTION, METABLOIC WASTES AND HORMONES around the body
- one circuit takes blood from the heart -> lungs, then back to the heart
- other loop takes blood around the rest of the body
- therefore, the blood has to go through the heart TWICE to complete one FULL circuit of the body
what is the hearts own supply of blood
- left and right CORONARY ARTERIES
describe the structure and function of the ARTERIES
- carry blood from heart -> rest of body
- walls are THICK and MUSCULAR
- walls have ELASTIC TISSUE : ability to STRETCH and RECOIL as heart beats -> helps MAINTAIN HIGH PRESSURE
- inner lining (endothelium) is FOLDED : allows artery to STRECH -> helps MAINTAIN HIGH PRESSURE
- all arteries carry OXYGENATED blood except PULMONARY ARTERIES
- PA takes DEOXYGENATED blood to the lungs
describe the structure and function of the ARTERIOLES
- arteries divide into smaller vessels ARTERIOLES
- ARTERIOLES form a NETWORK throughout the body
- BLOOD is directed to different areas (of demand) in the body by muscles inside the ARTERIOLES
- muscles in ARTIERIOLES CONTRACT to RESTRICT the blood flow
- muscles in ARTIERIOLES RELAX to ALLOW full blood flow
describe the structure and function of the VEINS
- take blood back to the HEART under LOW PRESSURE
- they have a WIDER LUMEN than arteries
- very LITTLE elastic or muscle tissue
- contain VALVES : stop the blood flowing backwards
- blood flow through the VEINS is helped by the CONTRACTION of the body muscles surrounding them
- all VEINS carry DEOXYGENATED blood (as oxygen has been used up by body cells)
- apart from PULMONARY VEINS, which carry OXYGENATED blood to the heart -> lungs
describe the structure and function of the CAPILLARIES
- ARTERIOLES branch into CAPILLARIES, which are the SMALLEST of the blood vessels
- substances, glucose and oxygen, are exchanged between cells and capillaries : ADAPTED FOR EFFICENT DIFFUSION
- always found very near cells in exchange tissues (alveoli in the lungs) : VERY SHORT DIFFUSION PATHWAY
- there are a LARGE number of CAPILLARIES = increases SA for exchange
- networks of capillaries in tissue are called - CAPILLARY BEDS
- endothelium : 1 cell thick
what is tissue fluid made of
- the fluid that surrounds cells in tissues
- made from small molecules that LEAVE the blood plasma, ex : OXYGEN, WATER and NURTIENTS
- tissue fluid DOES NOT contain RED BLOOD CELLS or BIG PROTEINS
- ^ because they are too large to be pushed out through the capillary walls
- cells TAKE IN OXYGEN and NURTIENTS from the tissue fluid
- cells RELEASE METABOLIC WASTE into the tissue fluid
how do substances move out of the capillaries and into the tissue fluid in a capillary bed
- substances move out of the capillaries and -> the tissue fluid IN A CAPILLARY BED by PRESSURE FILTRATION
explain the formation of tissue fluid
- at the ARTERIOLE END of capillaries
- there is HIGHER HYDROSTATIC PRESSURE in the CAPILLARIES, compared to the hydrostatic pressure in the TISSUE FLUID
- this forces WATER and DISSOLVED SUBSTANCES out of the CAPILLARIES
- LARGE PLASMA PROTEINS REMAIN in the CAPILLARY
explain the return of tissue fluid to the circulatory system
- at the VENULE END of capillaries
- hydrostatic pressure REDUCES as fluid LEAVES the capillary
- because of water loss, an INCREASING concentration of plasma proteins LOWERS the WP in the capillary
- water enters capillaries FROM the tissue fluid via OSMOSIS, DOWN a WP gradient
- excess water is taken up by LYMPH CAPILLARIES and RETURNED to the circulatory system through VEINS
what are the 2 causes of excess tissue fluid accumulation
- low concentration of protein in blood plasma/ high salt concentration
- high blood pressure -> high hydrostatic pressure
explain how low concentration of protein in blood plasma/ high salt concentration causes excess tissue fluid accumulation
- WP in capillary is not as low = WP gradient is reduced
- causes more tissue fluid to be formed at the ARTERIOLE end/ LESS water absorbed (via osmosis) at the VENULE end
explain how high blood pressure -> high hydrostatic pressure causes excess tissue fluid accumulation
- INCREASES outward pressure from ARTERIOLE end and REDUCES pressure from the VENULE end
- MORE tissue fluid formed at ARTERIOLE end = LESS water absorbed at VENULE end (via osmosis)
- lymph system may not be able to drain excess fast enough
what is the function of the right side of the heart
- pumps DEOXYGENATED blood
-> LUNGS
what is the function of the left side of the heart
- pumps OXYGENATED blood -> WHOLE BODY
name the parts of the heart
RIGHT SIDE
- pulmonary artery
- superior vena cava
- inferior vena cava
- right atrium
- semi lunar valve
- right atrioventricular valve
- right ventricle
LEFT SIDE
- aorta
- pulmonary vein
- left atrium
- semi lunar valve
- left atrioventricular
- cords
- left ventricle
what is the function of the RIGHT side of the heart
- vena cava
- right atrium
- atrioventricular valve
- right ventricle
- semilunar valve
- pulmonary artery
what is the function of the LEFT side of the heart
- pulmonary vein
- left atrium
- atrioventricular valve
- left ventricle
- semilunar valve
- aorta
what is the importance of a DOUBLE circulatory system
- prevents the mixing of oxygenated and deoxygenated blood : blood pumped to the body is FULLY saturated with oxygen for AEROBIC RESPIRATION
- blood can be pumped to body at a higher pressure : substances taken to/removed from body cells quicker/more efficiently
name the blood vessels entering and leaving the heart and LUNGS
- vena cava : deoxygenated blood from body tissues -> heart
- pulmonary artery : deoxygenated blood from heart -> lungs
- pulmonary vein : oxygenated blood from lungs -> heart
- aorta : oxygenated blood heart -> respiring body tissues
name the blood vessels entering and leaving the kidneys
- renal arteries : oxygenated blood -> kidneys
- renal veins : deoxygenated blood from kidneys -> vena cava
why is the wall of the left ventricle of the heart thicker than the right ventricle of the heart
- thicker muscle to contract with greater force
- to generate higher pressure to pump blood around the ENTIRE body
why are the ventricles thicker than the atria
- walls of the ventricles are thicker than the walls of the atria
- allows them to push blood out the heart, compared to the atria which only blood a short distance (INTO THE VENTRICLES)
how are the AV valves adapted to do their job efficiently
- link atria to ventricles
- stop blood flowing back into atria when ventricles contract
how are the SV valves adapted to do their job efficiently
- link ventricles to pulmonary artery and aorta
- stop blood flowing back into the heart when ventricles contract
how are the cords adapted to do their job efficiently
- attach AV valves to ventricles to stop them being forced into ATRIA when ventricles contract
what is the cardiac cycle
- ongoing sequence of contraction and relaxation of the atria and ventricles that keeps blood continuously circulating around the body
- volume of the atria and ventricles changes as they contract and relax
- pressure changes also occurs due to changes in chamber volume
what are the 3 stages of the cardiac cycle
- atrial systole
- ventricular systole
- diastole
what takes place in atrial systole, in the cardiac cycle
- atria contract, volume decreases, pressure increases
- AV valves open when the pressure in the atria > pressure in the ventricles
- SV valves remain shut, because pressure in arteries > pressure in the ventricles
- blood is pushed into the VENTRICLES
what takes place in ventricular systole, in the cardiac cycle
- ventricles contract, volume decreases, pressure increases
- AV valves shut when pressure in the ventricles > pressure in the atria
- SV valves open when pressure in ventricles > pressure in arteries
- blood is pushed out of the heart through ARTERIES
what takes place in diastole, in the cardiac cycle
- atria and ventricles relax, this causes volume to increase and pressure to decrease
- SV valves shut when pressure in arteries> pressure in ventricles
- AV valves open when pressure in atria> pressure in ventricles
- blood fills atria, via the veins, and it flows PASSIVELY to the ventricles
what is the equation for cardiac output
cardiac output = stroke volume x heart rate
what is cardiac output
the volume of blood pumped out of the heart per min
what is stroke volume
the volume of blood pumped in each heart beat
what is heart rate
the number of beats per min
what is a risk factor, in terms of cardiovascular disease
- an aspect a persons lifestyle or substances in a persons body/environment
- have been showed to increased rate of C disease
give examples of a risk factor for C disease
- age
- diet high in salt/saturated fat
- smoking
- lack of exercise
- genes
what is the function of the xylem tissue
transports water and mineral ions through the STEM, up the plant
-> LEAVES of plants
how is xylem tissue adapted for its function
- cells are joined with NO END WALLS = continuous tube -> water flows as a continuous column
- cells contain NO CYTOPLASM/NUCLEUS
-> easier water flow/no obstructions - thick cell walls with LIGNIN -> provides support/withstand tension/prevents water loss
- pits in side walls -> allows lateral water movements
explain the cohesion-tension theory of water transport in the xylem
leaf
- water lost from the leaf by TRANSPIRATION -> water evaporated from mesophyll cells into air spaces and water vapour evaporates through open stomata
- reduces the WP of mesophyll cells
- water is drawn out of the xylem DOWN a WP gradient
xylem
- TENSION is created in the xylem
- hydrogen bonds cause in cohesion between water molecules, so water is pulled up as a CONTINOUS COLUMN
- water also adheres (sticks to) to walls of xylem
root
- water enters roots via OSMOSIS
name the different environmental variables which affect the rate of TRANSPIRATION
- light intensity
- temperature
- wind intensity
- humidity
what is the effect of increasing light intensity
increases the rate of transpiration
what is the effect of increasing temperature
increases the rate of transpiration
what is the effect of increasing wind intensity
increases the rate of transpiration
what is the effect of increasing humidity
decreases the rate of transpiration
explain how increasing light intensity leads to an increased rate of transpiration
- stomata OPEN in light to let in CO2 for photosynthesis
- allows more water to EVAPORATE faster
- stomata close when its dark = low transpiration rate
explain how increasing temperature leads to an increased rate of transpiration
- water molecules gain KINETIC ENERGY as temp increases
- water evaporates faster
explain how increasing wind intensity leads to an increased rate of transpiration
- wind blows away water molecules from around the stomata
- decreases WP of air around the STOMATA
- increases WP gradient = water evaporates faster
explain how increasing humidity leads to a decreased rate of transpiration
- more water in air = higher WP gradient
- decreasing WP gradient from leaf to air
- water evaporates slower
describe the function of phloem tissue
transports organic substances, like sucrose, in plants
suggest how phloem tissue is adapted for its function
sieve tube elements
- NO NUCLEUS/ FEW ORGANELLES -> maximise space for/easier flow of organic substances
- end walls between cells perforated (sieve plate)
companion cells
- MANY mitochondria -> HIGH rate of transpiration to make ATP for active transport of solutes
what is translocation
- movement of assimilates/solutes, ex - sucrose, from source cells to sink cells by MASS FLOW
- source cells = where the solutes are made
- sink cells = where used/stored
give an example of a source cell
leaves
give an example of a sink cell
roots
explain the mass flow hypothesis for translocation in plants
- at source, sucrose is ACTIVELY TRANSPORTED, into phloem sieve tubes/cells by COMPANION CELLS
- ^ this LOWERS WP in sieve tubes so water enters from the xylem, by osmosis
- ^ this INCREASES hydrostatic pressure in sieve tubes (at source)/ creates a hydrostatic pressure gradient
- allows mass flow to occur (movement from the source -> sink)
- at sink, sucrose is removed by ACTIVE TRANSPORT to be used by respiring cells OR stored in storage cells
describe the use tracer experiments to investigate transport in plants
- leaf is supplied with a RADIOACTIVE TRACER, like CO2 which contains C14 (radioactive isotope)
- radioactive carbon is incorporated into organic substances during photosynthesis
- these move around the plant by TRANSLOCATION
- the movement is tracked using AUTORADIOGRAPHY or a GEIGER COUNTER
describe the use of ringing experiments to investigate transport in plants
- remove/kill phloem, eg -> remove a ring of bark
- bulge forms on the source side of the ring
- fluid from bulge has a HIGHER conc of sugars than below, shows sugar is transported in the phloem
- tissues BELOW the ring die because they cant get organic substances
what points should be considered when interpreting evidence from tracer and ringing experiments AND evaluating evidence for/against the mass flow hypothesis
- is there evidence to suggest the phloem is involved, instead of the xylem?
- if there evidence to suggest respiration/active transport is involved?
- is there evidence to show movement is from the source -> sink ?
- is there evidence to suggest movement is from a high -> low hydrostatic pressure?
- could movement be due to another factor, like gravity?
