Module 3:Exchange and Transport Flashcards
How do microorganisms obtain nutrients and remove waste
Exchange via their surface
Nutrients move in via diffusion
Waste moves out via diffusion
Why are microorganisms able to perform exchange via their surface
Large surface area to volume ratio
Short diffusion distance
Low demand
Why can’t animals/plants perform exchange via their surface
Small surface area to volume ratio
Multicellular (large diffusion distance and high demand)
Impermeable surface (prevent pathogens entering and reduce water loss)
Require exchange and transport systems
Exchange system
Increases rate of diffusion of nutrients in and wastes out
Transport system
Deliver nutrients and remove waste from all cells
Why do fish have specialised gas exchange systems
Multicellular organism so has small surface area to volume ratio, large diffusion distance, high demand and body surface is impermeable
Can’t perform gas exchange via surface
Need transport system
Structure of gills in fish
Many Gill filaments and Gill lamellae=large surface area
Gill lamella have a thin wall (shirt diffusion distance) and are permeable
Ventilation brings in pure water with high oxygen and low carbon dioxide
Circulation brings deoxygenated blood low oxygen and high carbon dioxide
Water and blood have countercurrent flow to maintain favorable concentration gradient all the way along Gill lamellae
Why do insects have specialised gas exchange systems
Multicellular organism so has a small surface area to volume ratio, large diffusion distance, high demand and body surface made of exoskeleton (impermeable barrier to reduce water loss)
Can’t perform gas exchange via their surface so require tracheal system
Structure of tracheal system in insects
Starts with openings on the body called spiracles
Spiracles contain valves which open for gas exchange and close to prevent water loss
Spiracles connected to trachea
Trachea connected to tracheoles
Tracheoles connect directly to respiring cells delivering oxygen and removing carbon dioxide
How does gas exchange occur in the tracheal system of insectx
At rest: down a concentration gradient oxygen moves in and carbon dioxide moves out by simple diffusion
When active: by ventilation, air inhaled for mass flow of oxygen in and air exhaled for mass flow of carbon dioxide out
Function of the lungs
Site of gas exchange in mammals
Oxygen in blood used in cells for respiration
Carbon dioxide out of the blood toxic waste product of respiration
What are the lungs made up of
Trachea Bronchi Bronchioles Alveoli Capillaries
Function of trachea, bronchi, bronchioles
Transport of air and filter air
Bronchioles also control the amount of air reaching the alveoli
Structure of the trachea and bronchi
Wall made of c shaped cartilage
Cartilage is so strong so trachea and bronchi don’t collapse
C shaped to give flexibility
Lining made of goblet cells and ciliates epithelial cells
Goblet cells make mucus which traps pathogens
Ciliated epithelial cells have cilia which pushes mucus up and out of the lungs
Structure of the bronchioles
Walls made of smooth muscle
Smooth muscle contracts, lumen narrows and bronchioles constricts
This occurs when surrounded by noxious gases to reduce the amount that reaches the alveoli
Lining made of goblet cells and epithelial cells
Adaptations of the alveoli
Millions of alveoli that are folded to increase the surface area
One cell thick/squamous epithelial cells for a short diffusion distance
Elastic tissue in wall (stretches with breathing in to increase surface area,recoils when breathing out to push air out)
Ventilation maintains concentration gradient of high oxygen and low carbon dioxide
Adaptation of capillaries
Millions of tiny capillaries for large surface area
One cell thick so short diffusion distance
Narrow lumen to increase diffusion time but decrease diffusion distance
Circulation maintains concentration gradient of low oxygen and high carbon dioxide
How does oxygen move from the alveoli to the capillaries
Simple diffusion
Passing through alveolar epithelium and capillary epithelium
How does carbon dioxide move from the capillaries to the alveoli
Simple diffusion
Capillary epithelium and alveoli epithelium
Inhalation
External intercostal muscles contract, internal relax Rib cage moves up and out Diaphragm contacts and flattens Increase in thoracic volume Decreased thoracic pressure Increased atmospheric pressure Air drawn into lungs
Exhalation
External intercostal relax, internal contract
Rib cage moves down and in
Diaphragm relaxes, dome shape
Decrease thoracic volume
Increased thoracic pressure, decrease atmospheric pressure
Air forced out
Aided by elastic recoil in alveoli
Formula for pulmonary ventilation
Tidal volume x ventilation rate
Tidal volume definition
Volume of air breathed in/out in one breath
Ventilation rate definition
Number of breaths per minute
Pulmonary ventilation definition
Volume of air breathed in/out in one minute
Function of intestines
Site of exchange of digested nutrients in mammals
Digestion definition
Hydrolysis of large insoluble molecules into small soluble molecules so they can move into the blood and into the body cells
Digestion of starch/glycogen
Into glucose by Amylase (salivary in mouth,pancreatic in small intestine)
And maltase/lactase/sucrase (lining of small intestine)
Digestion of proteins
Amino acids by endopeptidases, exopeptidases,dipeptidases
In stomach, small intestine, lining of small intestine
(In that order relating to enzyme above)
Lipids digestion
Into monoglycerides and two fatty acids by lipase found in small intestine
What do intestines absorb
Small intestine absorbs small soluble nutrients (glucose, amino acids,monoglycerides and fatty acids, vitamins and minerals)
Large intestine absorbs water
Why do humans/mammals require a specialised transport system
Multicellular so have large diffusion distance and high demands
Needs transport system to deliver nutrients and remove waste
Circulatory system
What is the circulatory system made of
Heart
Blood vessels
Blood
Why double circulatory system?
Heart pumps twice
Blood goes through heart twice in one cycle
Two separate blood flows
Why is the transport system in mammals called a closed circulatory system
Blood is transported in blood vessels
Helps to maintain blood pressure and redirect blood flow
Layout of circulatory system
Heart Arteries Arterioles Capillaries Venues Veins Heart
Artery/aterioles
Blood away from heart
Arterioles are small arteries
Capillaries
Site of exchange
Nutrients out
Waste in
Veins/venules
Return blood back to the heart
Venules are small veins
Brief blood flow in heart
Vena cava Right atrium Right ventricles Pulmonary artery Lungs Pulmonary vein Left atrium Left ventricle Aorta Body
Which ventricle wall is thicker
Left
Pumps blood to rest of the body
At higher pressure
Stronger contractions
Valves in the heart
Tricuspid= right AV
Bicuspid= left AV
two semi lunar
When are AV valves open or closed
Open=pressure in atria is greater than pressure in the ventricles
Closed=pressure in ventricles greater than pressure in the atria
When are SL valves open or closed
Open= pressure in ventricles greater than pressure in arteries
Closed=pressure in arteries greater than pressure in ventricles
Describe the process of the cardiac cycle
Filling stage:atria relaxed, ventricles relaxed, AV valves open,SL valve closed
Atrial systole:SAN in right atrium initiates heart beat and sends impulse across both atria so they contract and pushes all remaining blood into the ventricles
Ventricular systole:AVN picks up impulse, delays it so ventricles can fill and sends impulse down non conductive septum down the bundle of His, at apex the impulse goes up both walls of ventricles in purkinje fibres so ventricles contract from base upwards, when ventricles contract the AV valve closes and SL valve opens and blood leaves the heart
Ventricular diastole: SL valve closes Then the AV valve opens and filling starts again
What causes the heart sounds
When the valves close
1st when AV closes
2nd when SL closes
Formula for cardiac output
Stroke volume x heart rate
Stroke volume definition
Volume of blood pumped out of the heart in one beat
Heart rate definition
Number of beats per minute
Cardiac output definition
Volume of blood pumped out of the heart in one minute
Coronary heart disease and myocardial infarction
High blood pressure damages lining of coronary artery
Cholesterol builds up beneath the lining=atheroma
Atheroma breaks through lining and forms atheromaous plaque on lining in the lumen
Causes turbulent blood flow
Blood clot (thrombus) forms
Blocks coronary artery
Less blood flow to artery
Less glucose and oxygen delivered
Heart muscle cant respire
So it dies (myocardial infarction)
Risk factors of CHD
Age gender ethnicity
Saturated fats (increases LDL, deposits cholesterol in arteries to form atheroma)
Salts (increase blood pressure, lowers water potential of blood so it holds the water)
Smoking (nicotine increases heart rate and makes platelets more sticky,blood clot. Carbon monoxide permanently blocks haemoglobin)
Obesity and lack of exercise
Atheroma and aneurysm
Atheroma weakens wall of artery
Blood builds up in the wall
Wall swells then bursts=aneurysm
Role of arteries/arterioles
Generally carry oxygenated blood away from the heart
Exception is the pulmonary artery that carries deoxygenated blood to the lungs
Roles of veins/venules
Generally carry deoxygenated blood back to the heart
Exception pulmonary vein carries oxygenated blood back to the heart, hepatic portal vein carries deoxygenated blood from digestive system to liver for filtering
Function of arteries/arterioles
Carry blood away from the heart so need to withstand high pressure and maintain high pressure
Structure of arteries/arterioles
Narrow lumen=maintains pressure
Squamous epithelial cells=smooth lining to reduce friction
Thick wall=withstand pressure
Elastic tissue=stretches and recoils
Smooth muscle in wall (particularly arterioles)=contracts an relaxes to control blood flow, construction and dilation
Collagen in wall=prevents artery from tearing
Function of veins and venules
Returns blood back to the heart under low pressure
Structure of veins/venules
Wide lumen=ease of blood flow
Squamous epithelial cells=smooth lining to reduce friction
Thin wall=veins can be squashed by skeletal muscle pushing blood back to the heart
Valves in lumen=prevents backflow of blood
Function of capillaries
Site of exchange
3 locations:
alveoli (takes in oxygen, removes carbon dioxide)
microvilli (takes in glucose/amino acids)
all cells (deliver nutrients and remove waste)
Adaptation of capillaries
Many small capillaries=large surface area
Squamous epithelial cells=short diffusion distance
Pores between cells= fluid can move in and out
Narrow lumen= increase diffusion time and decrease diffusion distance
Content of blood
Plasma which carries Red blood cells White blood cells Platelets Nutrients Waste Proteins
How does exchange occur between capillaries and all cells
By mass flow
Fluid moves out of blood in capillaries carrying the nutrients
Fluid moves back into the blood in the capillaries carrying waste
Fluids in the body and their names
Blood= plasma
Surrounding cells=tissue fluid
Lymph system=lymph
How is tissue fluid formed and returned to the circulatory system
Arterial end there is a build up of hydrostatic pressure
Pushes fluid out of the capillary via pores
Fluid carries nutrients with it
Fluid surrounds cell, called tissue fluid
Venule end the fluid moves back in by osmosis
Capillary has low water potential due to the presence of proteins (too large to move out of the capillaries)
Any excess tissue fluid is picked up by the lymph system and deposited in the vena cava
Why does high blood pressure cause accumulation of tissue fluid
Increases hydrostatic pressure
Causes more tissue fluid to form
Not as much can be returned by the circulatory system
Why does diet low in protein cause an accumulation of tissue fluid
Water potential isn’t as low as normal
Not as much fluid can move back into capillary by osmosis
Pressure in arteries
Highest pressure as they connect directly with the heart
Pressured fluctuates (increases when ventricles contract so elastic tissue stretches, decreases when ventricles relax so elastic tissue recoils)
Overall decrease in pressure due to friction
Pressure in arterioles
Large decrease in pressure due to increase in total cross sectional area
Ensures pressure isn’t too high to damage capillaries
Pressure in capillaries
Hydrostatic pressure
Decreases due to a loss of fluid
Pressure venules/veins
Blood under low pressure
Function of red blood cells
Carry haemoglobin
Haemoglobin carries oxygen
Structure of haemoglobin
Globular protein (soluble and 3D shape) Quaternary structure made of 4 polypeptide chains Each chain carries a haem group Each haem group carries ferrous ion Each Fe2+ carries O2 Haemoglobin carries 4 x O2
Affinity definition
The level of attraction haemoglobin has to oxygen
High affinity= strong attraction
Role of haemoglobin
Load oxygen in the lungs and deliver it to the respiring tissues
Role of haemoglobin in oxygen transport
Haemoglobin has high affinity in the lungs due to high partial pressure of oxygen and low partial pressure of carbon dioxide, haemoglobin loads oxygen in the lungs and becomes saturated
Transported in the blood in red blood cell
At the respiring tissues haemoglobin has low affinity due to low partial pressure of oxygen and high partial pressure of carbon dioxide so oxygen is unloaded and haemoglobin becomes unsaturated
Relationship between oxygen partial pressure and affinity of haemoglobin
Positive correlation
As oxygen partial pressure increases affinity of haemoglobin increases
Produces s shaped sigmoid curve called oxygen dissociation curve
Middle portion of curve has a steep gradient so when respiring tissues change from resting to active and partial pressure falls there is a large drop in affinity so more O2 delivered to respiring tissues
Relationship between carbon dioxide partial pressure and affinity of haemoglobin
Negative correlation
CO2 partial pressure increases then saturation of haemoglobin decreases
Occurs at site of respiring tissues means carbon dioxide lowers ph of blood
Haemoglobin changes shape so oxygen is released, lowering affinity, curve shifts to right
Bohr shift
More oxygen delivered to respiring cells
How does a foetus receive oxygen
From mothers blood oxygen dissociates from mothers haemoglobin and associates with foetal haemoglobin in the placenta
Foetal haemoglobin has a higher affinity than mothers
Benefit of foetal haemoglobin having high affinity
ODC will shift to left as it has high affinity
Oxygen will dissociate from mothers haemoglobin and associate with fetal haemoglobin at the low partial pressure of oxygen so has enough oxygen for its needs
Hey do adults not keep foetal haemoglobin
The high affinity will mean less oxygen will be unloaded at the respiring tissues
Affinity of organisms in a low oxygen environment
High affinity
Curve to the left so it can readily associate oxygen at the low oxygen partial pressures
Affinity of active organisms
Low affinity
Curve to the right
More oxygen unloaded to meet cells demand for respiration
Affinity of small organisms
Large surface area to volume ratio Lose a lot of heat Need to respire to generate heat Low affinity Curve to right Unloads enough oxygen for cells demand of respiration
exchange systems in plants
leaf and root
leaf absorbs light and carbon dioxide for photosynthesis
root absorbs water and minerals
transport systems in plants
xylem and phloem
xylem transports water and minerals
phloem transports glucose/sugars
xylem transports one direction from roots to leaves but phloem travels in both directions
role of the roots
absorbs water and minerals
water by osmosis and minerals by active transport
what do plants need water for
photosynthesis
cytoplasm hydration
turgidity of cells
why do plants need minerals
magnesium- chlorophyll
nitrate-make amino acids
phosphate-make phospholipids/ATP/DNA
function of the xylem
transport water and minerals from roots up the plant to the leaves
structure of the xylem
long continuous hollow tube (no resistance to water flow)
narrow lumen
walls made out of lignin which is strong, waterproof and adhesive
walls contain pits/pores so water and minerals can leave
xylem cells are dead
how does water move up the xylem
loss of water at leaves (transpiration)
water move from the top of the xylem into the leaf by osmosis (transpirational pull)
applies tension to the column of water in the xylem
column of water moves up as one as the water particles stick together, cohesion
cohesion-tension theory
what is the process that allows water to move up the xylem
cohesion-tension theory
what supports the cohesion-tension theory
capillary action
adhesion
root pressure
definition capillary action
water automatically move up the narrow lumen of the xylem
adhesion definition
water particles stick to the lignin in the walls of the xylem
cohesion definition
water molecules stick together due to the hydrogen bonds that form between the slightly positive hydrogen atoms and slightly negative oxygen atoms
why does the diameter of a tree decrease during the
more light and higher temperature
increased rate of transpiration
increased transpirational pull
water pulled up the xylem by cohesion-tension
because the water has adhesion to the wall of the xylem the xylem walls are pulled inwards
structure of leaves
waxy cuticle (reduce water loss) upper epidermis palisade cells (photosynthesis) spongy mesophyll cells which contains air spaces (allows gas exchange) lower epidermis stomata and guard cells
adaptation of palisade cells for photosynthesis
located near top of the leaf so they are closer to light
large in size so there is a large surface area for light
thin cell wall, short diffusion distance of carbon dioxide
many chloroplasts for photosynthesis
large vacuole, pushes chloroplasts to the edge of the cell closer to light
structure of chloroplast
organelle for photosynthesis double membrane thylakoid discs stacks of thylakoids are called granum thylakoids contain chlorophyll thylakoids surrounded by fluid called stroma stacks are linked by lamella
how does exchange occur in leaves
lower epidermis containing guard cells
when turgid the guard cells form stomata
gas exchange occurs via stomata
in day: plant photosynthesises and respires, co2 moves in for photosynthesis and o2 moves out (some used in respiration)
at night: plant only respires, o2 moves in and co2 moves out
transpiration definition
loss of water vapour from the leaf via the stomata
process of transpiration
moist lining of spongy meosphyll cells evaporate forming water vapour
water vapour builds up in air spaces
if water vapour concentration is high enough and he stomata are open the water vapour diffuses out
what are the factors that affect the rate of transpiration
light
temperature
wind
humidity
how does light affect the rate of transpiration
more light
more stomata open
increase surface area for transpiration
how does temperature affect the rate of transpiration
increased temperature
increased evaporation
increases water vapour concentration
more kinetic energy
how does wind affect the rate of transpiration
more wind
maintains concentration gradient
disperses humid layer
how does humidity affect the rate of transpiration
less humid
less water vapour in the surrounding air
increase in water vapour
concentration gradient
what is a potometer
apparatus used to measure the rate of transpiration
principle of a potometer
as transpiration occurs from the leaves the plant will pull up more water from the potometer by cohesion-tension causing the bubble to move more towards the plant
more water lost by transpiration the more water taken up the further the bubble moves
measuring rate of transpiration
rate=transpiration volume/ time
transpiration volume= distance bubble moves x cross sectional area of tube (pi r ^2)
how to set up a potometer
choose healthy leaf and shoot
cut shoot underwater and connect to potometer underwater (prevents air bubbles entering/blocking the xylem)
ensure potometer is air tight and water tight
what does a potometer actually measure
rate of water uptake as a result of water loss from the plant
water loss due to: transpiration, photosynthesis, making cells turgid, loss from potometer
xerophyte definition
a plant adapted to reduce water loss (reduce transpiration)
adaptations of a xerophyte
spiky needle like leaves= reduce surface area
thick waxy cuticle= waterproof, impermeable barrier
densely packed spongy mesophyll= less air spaces, less water vapour build up
sunken stomata/hairy leaves/rolled up leaves= traps moist layer of air, reduces concentration gradient
function of phloem
transport organic material (sucrose) up and down a plant
structure of phloem
made of sieve tube with companion cells alongside
how does the phloem transport an organic material like sucrose
mass flow theory
sucrose loaded into the phloem at source
H+ actively transported from companion cells into the source
H+ diffuses back into the companion cells from the source
as they do they pull sucrose with them by co-transport
sucrose diffuses down the sieve tubes
lowers water potential of sieve tube so water follows by osmosis
water carries the sucrose by hydrostatic pressure (mass flow)
sucrose unloaded from phloem at sink
sucrose moves out of phloem into sink by diffusion
water follows by osmosis
enzymes of carbohydrate digestion
starch/glycogen: (salivary amylase in mouth, pancreatic amylase in small intestine) into maltose
maltose: (maltase on lining of small intestine) into glucose
lactose: (lactase on lining of small intestine) into galactose and glucose
sucrose: (sucrase on lining of small intestine) into glucose and fructose
enzymes forprotein digestion
endopeptidases: (in stomach) hydrolyse peptide bonds in the middle of the polypeptide chains into many smaller chains
exopeptidases: (in small intestine) hydrolyses peptide bonds at the end of the chains to leave dipeptidases
dipeptidases: (on lining of small intestine) hydrolyse dipeptides into amino acids
enzymes for lipid digestion
lipase in small intestine leaves monoglyceride and 2 fatty acids
adaptations of small intestine for absorption
folded to form villus= large surface area
cells lining small intestine have microvilli=large surface area
walls of small intestine are thin= short diffusion distance
rich blood supply= maintains concentration gradient
cells lining small intestine have transport proteins, enzymes and many mitochondria
absorption of glucose and amino acids in small intestine
sodium ions are actively transported from the cells lining the small intestine into the blood
lowers sodium ion concentration in the cell
sodium ions move from the lumen of the small intestine into the cell
pulls in glucose and amino acids via a cotransport protein
glucose and amino acids build up in the cell and move into the blood via diffusion
absorption of monoglyceride and fatty acids
lipids initially emulsified by bile into micelles
micelles digested by lipase into monoglycerides and 2 fatty acids
monoglycerides and fatty acids absorbed by cells lining the small intestine by simple diffusion
forms a chylomicron (lipid+cholesterol+lipoprotein)
enters lymph as lacteal then enters blood
what is lactose intolerance
person doesn’t make lactase enzyme
lactose remains undigested
undigested lactose in lumen of intestine lowers its water potential, water enters lumen by osmosis leading to water faeces
undigested breakdown of lactose by micro-organisms in large intestine gives off gas
