exchange and transport systems Flashcards
why do cells need oxygen
for aerobic respiration and nutrients
what waste products to cells excrete
carbon dioxide and urea
what needs to be exchanged between organisms
heat (as cells need to be kept at roughly the same temperature)
surface area to volume ratio
smaller animals = bigger SA:V, which means more heat loss
what do multicellular organism need
exchange organs and mass transport systems (as diffusion is too slow)
what is the mass transport system
circulatory system, which uses blood to carry hormones, antibodies, waste, glucose and oxygen around the body
heat exchange factors
size and shape
size on heat exchange
bigger surface area to volume ratio=faster heat loss, therefore small animals need a high metabolic rate to generate to stay warm
shape
compact=small SA:V, minimises heat loss
high SA:V =faster heat loss, lose moer water
what do small mammals need to eat
high energy foods such as seeds and nuts to deal with high metabolic rate
gas exchange surfaces adaptations
large surface area, thin (short diffusion pathway), maintains concentration gradient
single-celled organisms absorbing and releasing gas
by diffusion through their outer surface, through large surface area, thin surface
oxygen once it enters the cell
can take part in biochemical reactions as soon as it diffuses into the cell
what system do fish use for gas exchange
counter-current system
what is the counter-current system
water and blood flow in opposite directions which maintains a concentration gradient and means diffusion occurs as long as possible
how do fish get oxygen
water containing oxygen goes through its mouth and out the gills
what are gills made up of
thin plates called gill filaments (which gives a big surface area for exchange of gases)
what are gill filaments covered in
covered in lots of tiny structures called lamellae (which increase surface area further)
lamellae structure
lots of blood capillaries, thin surface layer of cells (to speed up diffusion)
what do insects use to exchange gases
tracheae
what are tracheae
microscopic air-filled pipes used for gas exchange
how does air move through the tracheae
through pores on the surface called spiracles , down the concentration gradient
tracheae branches
tracheoles
tracheoles adaptations to effective oxygen diffusion
have thin, permeable walls and go to individual cells (diffuses directly into respiring cells)
how do insects move air in and out of spiracles
rhythmic abdominal movements
carbon dioxide removal from insects
down concentration gradients towards the spiracles and released
what are dicotyledonous plants
group of flowering plants
why do dicotyledonous plants need C02
for photosynthesis
why do dicotyledonous plants need 02
respiration (produces CO2 as waste product)
what is the main exchange surface of dicotyledonous plants
surface of mesophyll cells in the lead
how are mesophyll cells adapted for gas exchange
large surface area
how do gases move through the leaf
in through stomata
what are stomata
special pores in the epidermis
what can stomata do
open to allow gas exchange, and close if the plant is losing too much water
what controls the stomata
guard cells
how to insects prevent losing too much water
close spiracles using muscles, have waxy cuticle over body, tiny hairs around spiracles (reduce evaporation)
how do guard cells control stomata
water enters the cells, making them turgid and opens stomata when plant has lots of water, when plant is dehydrated the guard cells lose water and become flaccid which closes the stomata
what are xerophytes
plants that live in warm, dry or windy conditions
what are plants that live in warm, dry or windy conditions
xerophytes
xerophyte adaptations
stomata sunk in pits layer of hairs curled leaves reduced number of stomata waxy, waterproof cuticles
stomata sunk in pits adaptation
trap moist air, reducing concentration gradient between leaf and air, and reducing diffusion out of the leaf and reducing evaporation
layer of hairs adaptation
traps moist air around stomata
curled leaves adaptation
(with stomata inside) protects from wind which reduces rate of evaporation and diffusion
reduced number of stomata adaptation
fewer places for water to escape
waxy, waterproof cuticle adaptation
reduces evaporation
lung structure
trachea, splits into 2 bronchi (one leading to each lung), branches into bronchioles, end in air sacs called alveoli
ventilation
breathing in and out - inspiration and expiration
inspirtation
air breathing in
inspiration sequence
active process external intercostal muscles contract diaphram muscles contract ribcage moves upwards and outwards diaphram flattens thoratic cavity volume increased lung pressure decerases air flows from high-low pressure, so flows into lungs
expiration
passive process, but can be forced external intercostal muscles relax diaphram muscles contract diaphram becomes curved again ribcage moves downwards thoratic cavity volume decreases
forced expiration
internal intercostal muscles contract which pulls ribcage further down and in , movement of the two sets of intercostal muscles is antagonistic
what is antagonistic
opposite
where does gas exchange in humans occur
alveoli
alveoli adaptations for gas exchange
lots in lungs (big surface area)
surrounded by network of capillaries (short diffusion distance)
thin exchange surface - alveolar epithelium is only one cell thick (short diffusion pathway)
steep concentration gradient
O2 across alveoli
diffuses out across alveolar epithelium and capillary endothelium, and into the haemoglobin in the blood
CO2 across alveoli
diffuses into the alveoli from the blood and is breathed out
lung diseases
pulmonary tuberculosis
fibrosis
asthma
emphysema
pulmonary tuberculosis
immune system builds a wall around the bacteria in the lungs forming tubercles (small hard lumps), infected tissue within these die and tidal volume is decreased
symptoms = cough, blood & mucus, chest pains
fibrosis
formation of scar tissue in lungs through e.g infection, so lungs can’t expand as much and tidal volume is reduced
what is tidal volume
volume of air in each breath
what is ventilation
number of breaths per minute
what is forced expiratory volume
volume of air that can be breathed out in 1 second
forced vital capacity
maximum volume of air possible to breathe forcefully out after a deep breath
asthma
airways become inflames/irritated, during an attack the smooth muscle lining in bronchioles contracts and mucus is produced, which constricts airways
emphysema
caused by smoking or long term exposure to air pollution, inflammation which attracts phagocyes to the area which produce an enzyme that breaks down elastin, so lungs can’t recoil, or destruction of alveoli
what is elastin
protein found in walls of alveoli
during dissection of the lungs
sharp but not too sharp tools, cutting board, cut lengthways along cartlidge
what breaks food down into smaller molecules
digestion
why are foods broken down
large molecules can’t be absorbed as they are too big to cross cell membranes (e.g starch, proteins)
what happens during digestion
large molecules are broken down into smaller molecules
why does digestion occur
so the molecule can be transported across the cell membrane and transported around the body
what are fats broken down into
fatty acids and monoglycerides
how are fats broken down
hydrolysis reactions
what are proteins broken down into
amino acids
how are proteins broken down
hydrolysis reactions
what breaks down the biological molecules during digestion
digestive enzymes
what are digestive enzymes produced by
specialised cells in the digestive system
where are digestive enzymes released into
the gut
what is amylase
digestive enzyme
what does amylase do
catylses conversion of starch into maltose
how does amylase do this
hydrolysis, breaks the glycosidic bonds
what produces amylase
salivary glands and pancreas
where is amylase released into
from the salivary glands = the mouth, from pancreas = small intestine
what are carbohydrates broken down by
amylase and membrane-bound disaccharides
what are membrane-bound disaccharides
enzymes attached to the membranes of epithelial cells lining the ileum
what is the ileum
final part of small intestine
what do membrane-bound disaccharides do
help break down disaccharides (e.g maltose, lactose, sucrose) into monosaccharides (glucose, fructose, galactose)
how do membrane-bound disaccharides do this
hydrolysis reactions, breaking gylcosidic bonds
how do monosaccharides move across the cell membranes of the ileum
specific transporter proteins
how are lipids broken down
lipase and the help of bile salts
what is lipase
digestive enzyme
what do lipase enzymes do
catalyse the breakdown of lipids into monoglycerides and fatty acids
how do lipases do this
hydrolysis, breaking ester bonds
where are lipases made
pancreas
where does lipase work
small intestine
where are bile salts produced
liver
what do bile salts do
emulsify lipids
why are bile salts important in lipid digestion
they increase the surface area that lipases can work on, by creating lots of small droplets instead of one big droplet
what are micelles
monoglycerides and fatty acids stuck with the bile salts
what do monoglycerides and fatty acids with bile salts form
tiny structures called micelles
what are proteins broken down by
endopeptidases
what are endopeptidases
a form of proteases
how do endopeptidases work
hydrolyse the peptide bonds inside a protein to break it down into amino acids
endopeptidases examples
trypsin
chymotrypsin
pepsin
where is trypsin made
synthesised in the pancreas
where is trypsin released
small intestine
where is chymotrypsin made
synthesised in the pancreas
where is chymotrypsin released
small intestine
where is pepsin released into
the stomach
where is pepsin released from
stomach lining
what conditions does pepsin work in
acidic
how are the acidic conditions produced in the stomach
the hydrochloric acid
what are proteins broken down into
exopeptidases
what do exopeptidases do
hydrolyse peptide bonds at the ends of protein molecules, and remove single amino acids from proteins
exopeptidases examples
dipeptidases
what do dipeptidases do
seperate the 2 amino acids that make up dipeptides by hydrolysing the peptide bond between them
where are dipeptidases found
cell-surface membrane of epithelial cells in the small intestine
what are the products of digestion
monosaccharides, monoglycerides and fatty acids, amino acids
what are the monosaccharides produced that are absorbed
glucose , galactose, fructose
how is glucose absorbed
by active transport with sodium ions via a co-transporter protein
how is galactose absorbed
by active transport with sodium ions via a co-transporter protein
how is fructose absorbed
by facilitated diffusion through a different co-transporter protein
where are the products of digestion transported across
across the ileum epithelial into the bloodstream
how are monoglycerides and fatty acids absorbed
diffuse directly across the membrane as they are lipid-soluble
what helps monoglycerides and fatty acids move towards the epithelium
micelles
how do micelles help move the products
they constantly break up and re-form, so release monoglycerides and fatty acids to be absorbed
how are amino acids absorbed
diffusion with sodium ions through a sodium-dependent transporter protein
how do sodium ions move into the iluem from epithelial cells
by active transport
how is oxygen carried around the body
haemoglobin
where is haemoglobin found
red blood cells
what do red blood cells contain
haemoglobin
what is haemoglobin
large protein with a quaternary structure (made up of 4 polypeptide chains)
what does each polypeptide chain contain in haemoglobin
haem group
what does the haem group contain
iron ion
what does the iron ion in the haem group do
gives haemoglobin its red colour
what does haemoglobin have
high affinity for oxygen
what does high affinity for oxygen mean
high tendancy to combine with oxygen
how many oxygen molecules can each haemoglobin molecule carry
4
what is oxyhaemoglobin
haemoglobin in the lungs joined with oxygen
how does oxyhaemoglobin form
when oxygen joins to haemoglobin in the red blood cells via a reversible reaction
what does oxygen dissociating mean
oxygen leaves oxyhaemoglobin
what is the chemical symbol for haemoglobin
Hb
what is the chemical symbol for oxyhaemoglobin
HbO8
what is the partial pressure of oxygen (pO2)
measure of oxygen concentration, greater concentration of dissolved oxygen in cells = higher partial pressure
what is the partial pressure of carbon dioxide (pCO2)
measure of concentration of C02 in a cell
what factor affects haemoglobins affinity for oxygen
the partial pressure of oxygen
what happens to haemoglobin when there is a high partial pressure of oxygen
oxygen loads onto haemoglobin to form oxyhaemoglobin
what happens to haemoglobin when there is a low partial pressure of oxygen
oxyhaemoglobin offloads oxygen
how does oxygen enter blood capillaries
at the alveoli in the lungs
what is the pO2 of alveoli
high
what happens to the haemoglobin at the alveoli
oxygen loads onto it to form oxyhaemoglobin due to high pO2
what happens to pO2 when cells respire
it lowers, as oxygen is used up (red blood cells deliver oxyhaemoglobin to respiring tissues, where it unloads its oxygen to be used)
what happens after oxyhaemoglobin offloads its oxygen to respiring cells
returns to the lungs to collect more oxygen and become oxyhaemoglobin again
what does a dissociation curve show
how saturated the haemoglobin is with oxygen at any given partial pressure
what does the dissociation curve look like
S shaped
what does the first oxygen entering the Hb do to the molecule
it makes it easier
how does carbon dioxide concentration affect oxygen offloading
higher partial pressure of carbon dioxide=haemoglobin gives up its oxygen more readily
what effect is carbon dioxide affecting oxygen offloading called
Bohr effect
why does carbon dioxide concentration affect oxygen offloading
it means cells recieve more oxygen during activity, as when cells respire they produce carbon dioxide which highers pCO2
what happens to the dissociation curve when there is high PCO2
it shifts right
what is different about haemoglobin in different organisms
different type, with different oxygen transporting capabilities
what haemoglobin do organisms in a low oxygen concentration habitat have
haemoglobin with a higher affinity for oxygen than humans, so the dissociation curve is to the left of ours
what does a shift left in the dissociation curve mean
haemoglobin with a higher affinity for oxygen
what haemoglobin do active organisms with a high oxygen demand have
haemoglobin with a lower affinity for oxygen than humans, so dissociation curve shifts to right
what does a shift to the right in the dissociation curve mean
haemoglobin with lots of surrounding oxygen
what transport system is the circulatory system
mass transport system
where does the circulatory system carry marterials to and from
carries them from specialised exchange organs to their body cells
what is the circulatory system made up of
the heart and blood vessels
what does the heart do
pumps blood through blood vessels to reach different parts of the body
what are blood vessels
arteries, veins, capillaries
what does blood transport
respiratory gases, products of digestion, metabolic wastes and hormones
what are the 2 circuits in the circulartory system
1=takes blood from the heart to the lungs then back to the heart,
2=around the rest of the body from the heart
how does the heart get its blood supply
left and right coronary arteries
what are arteries function
carry oxygenated blood from the heart to the rest of the body (except pulmonary arteries, which take deoxygenated blood to the lungs)
what are arteries adaptations
thick and muscular walls with elastic tissue (so can stratch and recoil as the heart beats), which helps maintain high pressure, folded inner lining which allows it to stretch and maintain high pressure
what is the inner lining of arteries
endothelium
what do arteries divide into
smaller vessels called arterioles
what do arterioles do
form a network throughout the body which have muscles inside that carry blood around the body by contracting to restrict blood flow or relaxing to allow full blood flow
what do veins do
take deoxygenated blood back to the heart under low pressure (except pulmonary veins which take oxygenated blood to the heart from the lungs)
what are veins adaptations
wider lumen with very little elastic or muscle tissue, contain valves to stop blood flowing backwards, body muscles surrounding contract to help with blood flow
what do arterioles branch into
capillaries
what are the smallest blood vessel
capillaries
where are capillaries found
near cells in exchange tissues
why are capillaries found here
so there’s a short diffusion pathway
how thick are capillary cell walls
one cells thick
why are capillary cell walls this thick
so there’s a short diffusion pathway
how many capillaries are there
a large number
why are there this number of capillaries
to increase surface area for exchange
what are networks of capillaries in tissue called
capillary beds
what is tissue fluid
fluid that surrounds cells in tissues
what is tissue fluid made from
small molecules that leave the blood pasma, doesn’t contain red blood cells or big proteins (too big to be pushed through capillary walls)
what gets taken out of tissue fluid by cells
oxygen and nutrients
what do cells put into tissue fluid
metabolic waste
what is the hydrostatic pressure are the start of the capillary bed
greater than in the tissue fluid
what does the difference in hydrostatic pressure mean
it forces fluid out of the capillaries and into the spaces around the cells, forming tissue fluid
what happens as the fluid leaves
hydrostatic pressure reduces in the capillaries, meaning it is lower than at the venule end
what does the fluid loss mean
the concentration plasma proteins also increases, and water potential at the venule end of the capillary bed is lower than the water potential in the tissue fluid
what does the water potential difference mean
some water re-enters the capillaries from the tissue fluid at the venule end by osmosis
what happens to excess tissue fluid
it is drained into the lymphatic system
what does the right hand side of the heart do
pumps deoxygenated to the lungs
what does the left hand side of the heart do
pumps oxygenated blood to the whole body
what is the thickness of the left ventricle muscular wall
thicker
why is the left ventricle this thickness
so that it can powerfully contract to pump blood all
why are the ventricle walls thicker than the atria
because they have to push the blood out of the heart around the body
what do the atrioventricular valves do
link the atria to the ventricles and stop blood flowing backwards
what do the semilunar valves do
link the ventricles to the pulmonary artery and aorta and stops blood flowing back into the heart
what do the cords between the atrioventricular valves do
connect the valves, and stops them from being forced up into the atria when the ventricles contract
what opens and closes the valves
the pressure in the heart chamber, higher pressure behind the valves forces the opens but high pressure infront forces it shut
what does the cardiac cycle do
pumps blood around the body
first stage of the cardiac cycle
ventricles relax, atria contract which decreases the chamber volume and increases the pressure which pushes blood into the ventricles increasing pressure and volume which ejects the blood
second stage of the cardiac cycle
atria relax, ventricles contract which decreases their pressure and increases their pressure, which forces the AV valves shut stopping back flow. pressure in ventricles is higher than in the aorta and pulmonary which forces the SL valves open
third stage of the cardiac cycle
ventricles and atria relax, blood returns to the heart and pressure starts to increase again
what do most cardiovascular diseases start with
atheroma formation
what is atheroma
when the inner lining of an artery is damaged, which causes white blood cells and lipids from the blood to clump together under the lining and form fatty streaks. overtime they build up and harden to form a fibrous plaque called atheroma
what does an atheroma do
blocks the lumen which restricts blood flow and increases blood pressure
example of cardiovascular disease
coronary heart disease, which occurs when artieries have lots of atheromas
what do atheromas do
increase the risk of aneurysms and thrombosis
what is an aneurysm
baloon-like swelling of the artery
how do atheromas increase the risk of aneurysms
they damage and weaken the arteries and narrow them (increasing blood pressure), and so when blood flows through the weakened artery at a high pressure it can push out the inner layers through the outer elastic layer and cause an aneurysm
what is caused if an aneurysm busts
haemorrhage
what is a haemorrhage
bleedin
what is thrombosis
formation of a blood clot
how can atheromas increase the risk of thrombosis
ruptures the endothelium, which damages the artery and leaves a rough surface where platelets and fibrin accumulate and form a blood clot, and debris from the rupture can cause another blood clot to form further down the artery
what can happen to the blood clot in arteries
can cause a blockage or become dislodged and block a blood vessel in another place
what causes a myocardial infarction
interrupted blood flow to the heart
what is a myocardial infarctions other name
heart attack
what are the symptoms of myocardial infarctions
pain in chest, shortness of breath, sweating
factors that increase risk of cardiovascular disease
high cholesterol and poor diet, cigarette smoking, high blood pressure, age, sex
how does high cholesterol and poor diet increase risk of cardiovascular disease
cholesterol is main consistuent of fatty deposits that form atheromas, diet high in fat increaes cholesterol, diet high in salts increases risk of high blood perssure
how does cigarette smoking increase risk of cardiovascular disease
because it contains nicotine and carbon monoxide, and decreases the amount of antioxidants in the blood, important for protecting cells
how does nicotine increase risk of cardiovascular disease
increases risk of high blood pressure
how does carbon monoxide increase risk of cardiovascular disease
combines with haemoglobin and reduces the amount of oxygen transported by the blood to tissues, so the heart doesn’t recieve enough oxygen
how does high blood pressure increase risk of cardiovascular disease
increases risk of damage to artery walls and so increases risk of atheroma formation
interpreting data on risk factors
describe data, draw conclusions, check any conclusions are valid, sample size
tissues involved in transport in plants
xylem and phloem
what does the xylem transport
water and mineral ions in solution
what does the phloem transport
organic substances (e.g sugars) both up and down the plant
what are the xylem vessels
long, tube-like formed from dead cells, no end walls, the part if the xylem tissue that trasnports the water and ions
how does water move up the xylem
cohesion and tension, the cohesion-tension theory
what is the cohesion-tension theory
water evaporated from the leaves (transpiration) which creates tension and pulls more water into the leaf and due to water molecules being cohesive and sticking together it means the whole column moves upwards, water enters through the roots
what is transpiration
the loss of water from a plants surface through evaporation
how does transpiration occur
water evaporates from the moist cell walls and accumulates in the spaces between cells in the leaf which moves down the concentration out of the cell when the stomata open
what factors affect transpiration rate
light, temperature, humidity, wind
how does light affect transpiration rate
lighter = faster transpiation rate as the stomata open for photosynthesis
how does temperature affect transpiration rate
higher temperature = faster rate as warmer molecules have more energy so evaporate faster, concentration gradient increases so water diffuses out faster
how does humidity affect transpiration rate
lower humidity = faster transpiration rate as concentration gradient increased
how does wind affect transpiration rate
windier = faster rate as concentration gradient decreased (water molecules moved away from the stomata)
what can a potometer be used for
estimate transpiration rate
how to use a potometer
cut it sideways, count bubbles
how to dissect plants
use tweezers and dissect them in water, transfer to dish containing stain and leave for a minute, rinse off in water and mount each onto a slide
how is phloem tissue adapted for transporting solutes
they have sieve tube elements and companion cells
what are solutes
dissolved substances
what are sieve tube elements
living cells that form the tube for transporting solutes, they have no nucleus and few organelles
what are companion cells
cells surrounding the phloem that carry out living functions for sieve cells (e.g providing energy needed for active transport of the solutes)
what is translocation
energy requiring movement of solutes to where theyre needed in plants through the phloem
whats another name for solutes
assimilates
where does translocation move to and from
from the source to the sink
what is the source
where its made (high concentration)
what is the sink
where its used up (low concentration)
how does the source and sink maintain a concentration gradient
through enzymes
how do enzymes maintain a concentration gradient between the source and sink
by breaking down the solutes at the sink into something else, which ensures a lower concentration
what explains phloem transport
mass flow hypothesis
first step of mass flow hypothesis
active transport is used to actively load the solutes from companion cells into the sieve tubes of the phloem at the source which lowers the water potential inside sieve tubes so water enters by osmosis from xylen to companion cells, which creates a high pressure inside the sieve tubes at the source end of the phloem
second step of mass flow theory
at the sink end, solutes are removed from phloem to be used up which increases the water potential and means water leaves the tubes by osmosis, which lowers pressure inside sieve tubes
third step of mass flow theory
result is a pressure gradient from the source to the sink which pushes solutes along the sieve tubes towards the sink to be used or stored
evidence for mass flow (4)
radioactive tracer can be used to track movement of organic substances, pressure in the phloem can be investigated using aphids (where sap flows out quicker nearer leaves), metabolic inhibitor stops translocation (active transport is involved), ring of bark removed = bulge above the ring (shows it flows downwards)
evidence against mass flow (2)
sugar travels to many different sinks not the one with highest water potential, sieve plates would create a barrier to mass flow (lots of pressure required to get through them at a reasonable rate)
how can the translocation of solutes be demonstrated experimentally
using radioactive tracers
method of translocation of solutes being demonstrated experimentally
supplying part of plant with an organic substance that has a radioactive label which will then be incorporated into organic substances produced and moved by translocation, and can be tracket using autoradiography to see which part of the plant its been spread to (by freezing the plant, then placed on photographic film where the plant that contains radioctive material will turn black)
