how do cells get their energy
by oxidising foods such as glucose, this is called respiration
if cells are to respire aerobically, what do they need
a continuous supply of oxygen from the blood, and carbon dioxide to be removed.
what is breathing
the mechanism that moves air into and out of the lungs, allowing gas exchange to take place.
what is the gas exchange system
the lungs, ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranes of the thorax
where does gas exchange take place
in the lungs
where are the lungs
enclosed in the chest or thorax by the ribcage and a muscular sheet of tissue called the diaphragm.
what causes the movement of air into and out of the lungs
the actions of the lungs and diaphragm
describe the process of breathing in
the intercostal muscles and the diaphragm contract
thorax volume increases because the muscles pull the sternum up and out, so the pressure decreases, drawing air in.
describe the process of breathing out
intercostal muscles and diaphragm relax.
thorax volume decreases because the ribcage and sternum drop in and down, so the diaphragm moves up, increasing pressure, and forcing air out.
what happens to the air when we breathe in
it enters our nose or mouth and passes down the windpipe or trachea. the trachea splits into two tubes, the bronchi, and each bronchus divides into smaller and smaller bronchioles, which ends at alveoli where gas exchange takes place
what do the walls of the trachea and bronchi contain
rings of gristle or cartilage
what do the rings of cartilidge do
support the airways and keep them open when we breathe in
what is the inside of the thorax seperated from the lungs by
two thin, moist membranes called the pleural membranes
purpose of the pleural membranes
they make a continuous and airtight seal around the lungs. the pleural cavity is filled with a thin layer of pleural fluid, which acts as lubrication, so that the surfaces of the lungs don’t stick to the inside of the chest wall when we breathe.
explain mucus and it’s role in the airway
some cells in the lining between the trachea and the larger airways are lined with a layer of cells that secrete mucus, which traps particles of dirt or bacteria that are breathed in.
explain cilia and it’s role in the airway
the tiny hair-like structures beat backwards and forwards, sweeping the mucus and trapped particles out towards the mouth. this means they don’t reach the lungs, so they prevent infection.
what is ventilation
the moving of air in and out of the lungs
what is required in ventilaiton
a difference in air pressure - the air moves from a place where it is high to one where it is low.
where is deoxygenated blood pumped from and to
from respiring tissues of the body where it has given up some of its oxygen to the cells, and gained carbon dioxide, to the heart, to the lungs, and passes through the capillaries surrounding the alveoli.
what are the alveoli and the blood separated by
two cell walls: the cells making up the walls of the alveolus, and the capillary wall itself. this is the distance of less than a thousandth of a millimetre.
explain how the gas exchange within the alvelous works
the air in the alvelous has a higher concentration of oxygen than the blood entering the capillary network . this means oxygen can diffuse across the wall of the alveolus and into the blood. at the same time, there is more carbon dioxide in th air than in the lungs. this means there is a diffusion gradient for carbon dioxide in the other direction, so it diffuses the other way, out of the blood and into the alveolus.
what is the result of the gas exchange within the alveolus
the blood which leaves the capillaries and flows back to th heart has gained oxygen and lost carbon dioxide. the heart then pumps the oxygenated blood round the body again, to supply thee respiring cells.
why is it important for the gas exhange system to be clean and clear
the alveoli need to be free from dirt particles and bacteria, and have as big a surface area as possible with the blood.
give three diseases smoking is associated with
lung cancer, bronchitis and emphysma.
what other diseases does smoking contibute to
conarary heart disease, ulcers of the stomach and intenstine. pregnant women who smoke are more likely to give birth to underweight babies.
what structure do the chemicals in cigarette smoke destroy (in the trachea and bronchi)
cilia
what does the reduced number of cilia due to smoking lead to
the mucus is not swept away from lunfs, but remains to block the air passages. this is made worse as the smoke irriates the lining of the airways, stimulating the cells to secrete more mucus. this blocks the airwaus, and is the source of ‘smokers cough’.
how does smoking damage the alveoli
smoke damages the walls of the alveoli, which break down and fuse together again, forming large and irregular air spaces.
how does damaged alveoli lead to emphysma
it greatly reduces the surface area for gas exchange. the blood of a person will then carry less oxygen.
does smoking cause lung cancer
it is not proven but there is a large correlation between them.
what is the strongly addictive drug in cigarettes
nicotine.
give some of the chemicals found in cigarettes
carbon monoxide, arsenic, ammonia, cyanide
what are the chemicals in cigarettes that can cause cancer called
carcinogens
where are the carcinogens contained
in tar, which collects in the lungs
when does cancer happen
when cells mutate and start to divide uncontrollably
how does carbon monoxide negatively affect the body
it reduces the ability of blood to carry oxygen
how is oxygen carried around the body
in the blood in the red blood cells, attached to haemoglobin.
what does carbon monoxide do to the blood
it combines with the haemoglobin much more tightly than oxygen can, forming a compound called carboxyhaemoglobin.
what happens if a pregant woman smokes
she will be depriving the unborn fetus of oxygen. this has an effect on its growth and development and leads to the mass of the baby at birth being lower, on average.
how many people die from tobacco related illnesses a year
nearly 6 million
what are the withdrawl symptoms of giving up smoking
cravings, restlessness and a tendency to put on weight
what are the ways that help smokers quit
vaping, nicotine patches or nicotine chewing gum.
why do we need food
to supply us with ‘fuel’ for energy
to provide materials for growth and repair of tissues
to helo fight disease and keep our bodies healthy
what is a balanced diet
a diet that provides enough of the essential substances in the correct proportions.
what substances do we need and can get from food
carbohydrates lipids proteins minerals vitamins dietary fibre water
how much mass of the human body is made up by carbohydrates
1%
how do cells get energy from carbohydrates
they oxidise the glucose in respiration
where is glucose found
in fruits and vegetables
give three other types of sugar
fructose
lactose
sucrose
two properties of sugar
tastes sweet
dissolves in water
what is the main sugar transported through plant stems (phloem)
sucrose
where do we get most of the carbohydrate we need
from starch
does starch dissolve
no it is a large, insoluble molecule
why is starch found as a storage component in many plants
it doesnt dissolve
what is starch
a polymer of glucose - long chains of hundreds of glucose molecules joined together
starch is only found in…
plant tissues
what is a very similar carbohydrate to starch
glycogen
where is glycogen found
tissues such as liver and muscle, where it acts as a store of energy
what is glycogen
a polymer of glucose
what is cellulose
polymer of glucose
what does cellulose make up
cell walls
can humans digest cellulose
no, our gut doesn’t produce the enzyme to break it down.
what is the point of cellulose for humans
it isn’t a source of energy but it forms dietary fibre which gives the muscles of the gut something to push against. this keeps food contents moving, avoiding constipation and helps to prevent serious diseases of the intestine like colitis and bowel cancer
what elements do lipids contain
carbon hydrogen oxygen
what elements do carbohydrates contain
carbon hydrogen oxygen
what is th difference in chemical formulae in lipids and carbohydrates
lipids have a much lower proportion of oxygen
how much of our body’s mass is made from lipids
10%
what two molecules make lipids
glycerol and fatty acids
what is glycerol
an oily liquid
whats the proportion of glycerol to fatty acids in lipids
one glycerol molecule is joined to three fatty acid molecules
how much of our body’s mass is made up from protein
18%
why do we need protein
growth and repair of tissues
what foods contain protein
meath, fish, cheese, eggs
how much protein do we need a day
roughly 70g
what happens if you have a very limited protein intake
you can develop a disease called kwashikor
what are proteins made of
20 different sub-units called amino acids
what element are in amino acids
carbon hydrogen oxygen and nitrogen
how are amino acids usually arranged
folded up or twisted into spirals, with cross links holding them together
what contributes to what a protein will become
the shape and order of the amino acids
what does protein become in the body
collagen and keratin in the skin and nails
enzymes
haemoglobin
antibodies
role of calcium
making teeth and bones
examples of foods rich in calcium
dairy, fish, bread, vegetables
role of phosphorus
making teeth and bones, part of many chemicals like DNA and ATP
examples of food rich in phosphorus
most foods
role of sodium
body fluids, like blood
examples of food rich in sodium
common salt, most foods
role of chlorine
body fluids, like blood
examoles of food rich in chlorine
common salt, most foods
role of magnesium
making bones, found inside cells
examples of food rich in iron
red meat, liver, eggs, some vegetables like spinach
role of iron
green vegetables
examples of food rich in magnesium
green vegtables
what will happen if someone doesnt get enough of a mineral
mineral deficiency disease
what can result from not enough calcium
poor bone development
what can result from a lack of vitaminD
rickets
what can result from a lack of iron
anaemia
vitamin A recommended daily amount
0.8mg
vitamin C recommended daily amount
80mg
vitamin D recommended daily amount
5 microg
use of vitamin A
making a chemical in the retina, also protects the surface of the eye
effect of deficency of vitamin A
night blindness, damaged cornea of eye
foods rich in vitamin A
fish liver oils, liver, butter, margarine, carrots
use of vitamin C
sticks together cells lining surfaces such as the mouth
effect of deficency of vitamin C
scurvy
foods rich in vitamin C
fresh fruit and vegtables
use of vitamin D
helps bones absorb calcium and phosphate
effect of difeciency of vitamin vitamin D
rickets, poor teeth
foods rich in vitamin D
fish liver oils, made in the skin in sunlight.
test for starch
put a little starch on a dropping tile.
add a drop of yellow-brown iodine solution.
the iodine will react with the starch, forming a blue-black colour.
test for glucose
put glucose in a test tube and add water (should be around 2cm deep).
shake it to dissolve the glucose.
add serveral drops of blue benedict’s solution.
prepare a water bath by half filling a beaker with water and heating it on a tripod, gauze and bunsen burner.
put the test tube in the water bath and wait as it boils.
the solution will turn a brick red if glucose is present. (this is the precipitate of copper oxide)
why is glucose called a reducing sugar
the test for glucose involves reducing an alkaline solution of copper sulfate to copper oxide
are all other sugars reducing sugars
fructose and lactose and other disaccharides are but not sucrose, which will stay blue in the solution.
test for protein (biuret test)
put some protein (like powdered egg white) in a test tube and add some water should be about 2cm deep).
shake to mix.
add an equal volume of 5% potassium hyrdorixde and shake.
add two drops of 1% copper sulfate solution.
shake until a purple colour develops if protein is present.. sometimes these two solutions will already be mixed called ‘biuret solution’
test for lipids
use a pipette to put one drop of olive oil in a test tube.
add 2cm depth of ethanol.
shake to dissolve.
pour this into a testube 3/4 with cold water.
a white cloudy layer will form on top of the water, formed by the thanol dissolving in the water and leaving the lipid behind as a suspension of tiny drops (emulsion).
what is the energy content of food measured in
kilojoules
if a gram of carbohydrate is fully oxidsed how much energy is produced
around 17kJ
if a gram of protein is oxidise how much energy is produced
around 18kJ
if a gram of lipid is oxidised how much energy is produced
around 39kJ
what does the amount of energy needed depend on
age
mass/body size
activity levels
how do you calculate the amount of energy in a food sample
find the mass by using a balance
put 20cm cubed of water in a boiling tube, and support it in a clamp on a stand.
record the temperature of the water.
hold the food (speared on a mounted needle) over a bunsen burner flame until it catches on fire, and continue until it will no longer catch on fire.
record the final temperature of the water, and then calculatae using the equation.
what is the equation for energy in joules per gram (of food)
mass of food
what is digestion
the breaking down of food so the products can be absorbed through the wall of the gut.
what is digestion sped up by
enzymes/biological catalysts
give some digested molecules
sugars, fatty acids, glycerol, amino acids, minerals, vitamins
what happens to the digested molecules
they travel around the body in the blood, and when they reach the tissues they are reassembled into the molecules that make up our cells
what is chemical digestion
the use of enzymes to speed up digestion
what is mechanical digestion
the physical breakdown of food i.e. chewing and peristalysis
what do the walls of the intestine contain
two layers of muscle
describe the circular muscle layer
it has fibres arranged in rings around the gut
describe the longitudianl muscle layer
it has fibres running along the length of the gut
what happens when the circular muscles contract and the longitudinal muscles relax
the gut is made narrower
what happens when the longitudinal muscles contract and the circular muscles relax
the gut becomes wider
what is the waves of muscle contraction in the walls of the intestine clalled
peristalsis
what parts of the human digestive system break down food using enzymes
the mouth, the stomach, and the first part of the small intestine (called the duodenum), either made in the gut itself or in the duodenum.
where does digestion continue after the duodenum
the last part of the small intestine (ileum) and it is here where the digested food is absorbed.
describe digestion in the large intestine
absorbs water out of the remains and stores the waste products (faeces) before they are removed from the body.
which enzymes digest carbohydrates
carbohydrases
which enzymes digest proteins
proteases
which enzymes digest lipids
lipases
role of saliva in digestion
helps to moisten the food and contains the enzyme amylase which starts the breakdown of starch.
sources of carbohydrases
salivary glands
pancreas
wall of small intestine
sources of proteases
stomach wall
pancreas
wall of small intestine
sources of lipases
pancreas
where do carbohydrases act
mouth
small intestine
where do proteases act
stomach
small intestine
where do lipases act
small intestine
why is food held in the stoamch for several hours
for inital digestion of protein
is the stomach acidic or alkaline
acidic (HCl)
optimum pH for protease
2
why is the stomach contents acidic
to kill bacteria taken into the gut with food
what is the semi-digested food held back in the stomach by
a spinchter muscle.
what happens when the spinchter muscle relaxes
it releases food into the first part of the small intestine
where is bile produced
the liver
where is bile stored
gall bladder and passes down the bile duct on to the food
what does bile do
turns any large lipid globules in the food into an emulsion of tiny droplets. this increases the surface area of the lipid, so that lipase enzymes can break it down more easily.
bile and pancreatic juice are both…
alkaline
what other function does bile and pancreatic juice have
alkaline to neutralise the hydrochloric acid which comes from the stomach.
It breaks down large drops of fat into smaller ones. This is known as emulsification. The larger surface area allows lipase to chemically break down the lipid into glycerol and fatty acids faster.
why does the ileum have a large surface area
to absorb the soluble parts of digestion quickly into the blood
how does the ileum have a large surface area
length, folds in it’s lining and villi.
how long is each villi
1-2mm long
what do villi have
microvilli
what does each villus have
a network of blood capillaries. this is where most of the digested food enters, except the lacteals (products of fat digestion) which enter through a tube in the middle of a villus.
what is the surface of a villus made from
epithelium
what does the epithelium allow
a short distance between the capillaries and the ileum for faster diffusion.
what do epithelium cells contain
mitochondria for active transport
what do the muscle fibres in the ileum do
contract, so the villi are in constant motion, allowing them to stay in contact with the contents of the ileum, and maintaining a steep concentration gradient.
what do the blood vessels of the ileum join up to form
the hepatic portal vein
what does waste material of digestion consist of
cellulose (fibre), water, bacteria.
function of colon
absorb most of the remaining water.
after the colon has absorbed most of the water from waste material where does it go
rectum, until expelled out of the body by the anus.
in mammals, what does blood transport
oxygen
carbon dioxide
nutrients
urea
what is transported by blood
hormones antibodies oxygen carbon dioxide nutrients
why dont very small organisms have circulatory systems
materials can move around the cells without a special system, and they can get oxygen through diffuion. they can do this bcause they have a high supply to demand ratio.
what does the area of the cells surface determine
how much oxygen the organism can get (supply rate)
what does the volume of the cell determine
how much oxygen the cell uses (demand rae)
ratio of supply to demand
volume
why cant large animals use diffusion to get what thyey need
there isnt enough surface to supply all the volume. so we have evolved special gas exchange organs and circulatory systems, the gills of fish and the lungs of mammals are linked to a circualtory system that carries oxygen to all parts of the body.
single circulatory system
blood is pumped from heart to gas exchange organ to the rest of the body
double circulatory system
blood is pumped from heart to gas exchange organ back to the heart and then to the rest of the body
pulmonary circulation
deoxygenated blood leaves the heart through the pulmonary arteries, and is circulated through the lungs where it becomes oxygenated. it then returns to the heart through the pulmonary veins
systemic circulation
oxygenated blood leaves the heart through the aorta, and is circulated through all other parts of the body, where it unloads its oxygen. deoxygenated blood returns to the heart through the vena cava
why is a double circulatory system more efficent than a single circulatory system
it is pumped through the heart twice, so higher pressures can be maintained. the blood travels more quickly to organs. in a single circulatory system, it loses pressure and travels more slowly.
the human circulatory ssytem comprises:
the heart - pump
blood vessels - carry blood round the body
blood - transport medium
arteries
carry blood away from heart and towards other organs
high pressure
elastic tissue in the walls of the arteries allows them to stretch and recoil maintaining this high blood pressure
thick muscular wall to control the flow of blod
veins
carry blood towards the heart and away from other organs
pressure lower than arteries so they can be thinner and contain less elastic tissue and muscle
capillaries
carry blood through organs, linking the arteries and veins
substances are transferred between the blood in the capillary and the cells.
to do this, the capillaries must be small enough to fit between cells and allow materials to pass through their walls which are one cell thick for a short distance of diffusion. red blood cells cann just fit through capillaries
cardiac cycle
vena cava and pulmonary vein atriums bicuspid and tricuspid valves ventricles semi lunar valves aorta and pulmonary artery
which side of the heart pumps blood to only the lungs
the right ventricle
which side of the heart pumps blood to the rest of the body
the left ventricle
purpose of valves
so that blood only flows in one direction
what are the walls of the heart made of
cardiac muscle which can contract then relax continously without becoming fatigues
how does blood reach the cardiac muscle
via conorary arteries and returned via conoary veins
conorary heart disease
the conorary arteries are very narrow and can be easily blocked by a build up of fatty substances like cholesterol in the walls. this will cut off an area of blood supply to an area of cardiac muscle, and means it can no longer receive oxygen and glucose and is unable to contract, resulting in a heart attack.
factors that contribute make conorary heart disease more likely
heredity high blood pressure diet smoking stress lack of exercise
heart normal bpm
70
when we need more oxygen due to exercise what happens
the heart bpm increases so that blood can be transported faster and there will be an increased supply of oxygen.
what is our fight or flight respise triggered by
a release of adrenaline that supplies extra blood to our muscles, and enable them to fight or run away
what are changes in heart bpm controlled by
medulla in the brain
how does the medella control heart rate
receptors detect the increase in carbon dioxide produced and send nerve impulses through the sensory nerve to the medulla. the medulla responds by sending nerve impulses along the accelerator nerve. when CO2 production returns to normal, it sends nerve impulses along a decelerator nerve.
describe plasma
liquid part of blood: mainly water
describe red blood cells
biconcave
disc like cells with no nucleus
millions in each mmcubed of blood
function of plasma
carries the blood cells, dissolved nutrients, hormones, carbon dioxide and urea. around the body. also distributes heat
function of red blood cells
transport of oxygen - mainly haemoglobin which loads oxygen into the lungs and unloads it in other regions of the body
what are red blood cells also known as
erythocytes
describe lymphocytes
about the same size as red cells with a large nucelus
function of lymohocytes
produce antibodies to destroy microorganisms, some persist in our blood after infection and give us immunity
describe phagocytes
much larger than red cells, with a large spehrical nucleus
function fo phagocytes
digest and destroy bacteria and other microorganisms that have infected our bodies
describe platelets
the smallest cells, are really fragments of other cells
function of platelets
release chemicals when we cut ourselves
what does haremoglobin combine with where there is a high conc of oxygen in the surroundings in the lungs
oxygen to form oxyhaemoglobin
when does oxugemoglobin turn back into haemoglobin
when it unloads the oxygen in the tissues
what is phagocytosis and how does it work
phagocytes engulfing microorganisms by changing their shape and producing extensions of their cytoplasm called pseudopodia
what percent of white blood cells are lymphocytes
25%
what percent of white blood cells are phagocytes
70%
how do antibodies help
pathogens have antigens on their surface, and antibodies (soluble proteins) stick to the surface of the antigens and destroy the pathogen
how do antibodies destroy the pathogen
causing them to stick together so that phagocytes can ingest them easier
acting as a label for quick recognition by phagocytes
causing bacterial cells to burst open
neutralising toxins
purpose of memory cells
some lymohocytes remain the blood as memory cells which provide immunity as if the same microorganism reenters the memory cells will remember
how do vaccines work
lymphocytes will recognise the antigens and act as if that was a microorganism entering the bloodstreanm. the person now has immunity. next time the (now secondary) immune response will be much faster
how do platelets help
air stimulates them to produce fibrinogen which would make plasma turn into insoluble fibres of a protein called fibrin. this can form a network across a wound and trap red blood cells to reduce blood loss.
stimulus def
change in an animals surroundigns
response def
reactuon to the change in surroundings
receptor
organ that detects the change
effector
produce an effect
what are nerve impulses
tiny electrical signals
what type of energy does the eye (retina) receive
light
what type of energy does the ear receive
sound
what type of energy does the ear receive
mechanical (kinetic)
what type of energy does the tongue receive
chemical
what type of energy does the nose receive
chemical
what type of energy does the nose receive
smell
what type of energy does the skin receive
mechanical (kinetic)
what type of energy does the muscle receive
mechancial (kinetic)
name for nerve cell
neurone
impulses from receptors pass along nerves containing
sensory neurones until they reach the brain and spinal cord.
what are the brain and spinal cord referred to as
the central nervous system
other nerves contain ______ that transmit impulses to muscles and glands
motor neurones
what are the fine cytoplasmic extensions of a motor neurone called
dendrons which then form finer extensions called dendrites
what are junctions between neurones called
synapses
what is the axon
the fibre that carries impulses to the effector organ
what is the axon covered by
a sheath made of a fatty material called myelin
what does the myelin sheath do
insulate the axon and prevent short circuits with other axon
where is the cell body of a motor neurone
at one end of the fibre in the CNS
where is the cellbody of a sensory neurone
on a side branch of the fibre just outside the CNS
what is the sclera
the tough outer coat of the eye
what is the cornea
a transparent window which lets light through
what is the iris
the coloured ring of tissue
what is the pupil
the black hole in the middle of the eye
what is the choroid
a dark layer under the sclera
what is the retina
light-sensitive later where light energy is converted into the electrical energy of nerve impulses. it contains rods and cones
whats the optic nerve
the way sensory neurones pass the impulses to the brain
when do rod cells work well
dim light but not different colours
when do cone cells work well
differnet colours but not dim light
where does refraction to see an image take place in the eye
first at the air/cornea boundary and again at the lens
role of iris
to control the amount of light entering the eye
in bright light what happens to the eye
circular muscles cotnract
radial muscles relax
pupil constricts
in dim light what happens to the eye
circular muscles relax
radial muscles contract
pupil dilates
what is the blind spot
where the optic nerve leaves the eys so an image can not be formed
what is accomodation
the changes that take plae in the eye which allow us to see objects at different distances
focussing on a distant object
ciliary muscles relax
suspensory ligaments pulled tight
lens flat
focussing on a nearby object
ciliary muscles contract
suspensory ligaments slack
lens more rounded
what is a nerve arc
the nerve pathway of a reflex
reflex action def
rapid automatic (or involunatry) response to a stimulus. usually to protect the body.
what is a synapse
a gap between two cells
how is a synapse crossed
impulses secrete a chemical called a neurotransmitter which diffuses across the fap and attaches to the membrane of the second neurone and starts off impulses there. it is then broken down by an enxyme.
what is a gland
an organ that releases or secretes a substance.
what are exocrine glands
they sevrete products through a tube called a duct
what are endrocrine glands
ductless glands, secrete their homones through blood vessels.
differences between the nervous and endocrine system
nervous: works by nerve impulses transmitted through nerve cells really fast and instant effect short- lived response very localised effect endocrine: works by hormones transmitted through bloodstream slower and take longer to act longer-lasting response widespread effect on different organs
functions of pitiuary gland horomnes
FSH: stimulates egg development and oestrogen, secretion in females and sperm production in males
LH: egg release in females and testosterone production in males,
ADH: controls the water content of the blood
hormones produced by pituatary gland
FSH (follicel stimulating hormoine) lutenising hormone (LH) antidiuretic hormone (ADH)
hormones produced by thyroid
thyroxine
function of hormones produced by thyroid
controls the bodys metabolic rate
hormones produced by pancreas
insulin
glucagon
functions of hormones produced by pancreas
insulin: lowers blood glucose
glucagon: raises blood glucose
hormones produced by testes
testosterone
function of hormones produced in testes
controls the development of male secondary sexual characteristics
hormones produced by ovaries
oestrogen
progesterone
function of hormones produced by ovaries
oestrogen: controls the development of female secondary characteristics
progesterone: regulates menstrual cycle
is the pancreas endocrine or exocrine
both
endo: secretes hormones involved in regulation of blood glucose
exo: secretes enxyme through pancreatic duct into small intenestine
body preparations for fight or flight (7)
higher breathing rate
higher bpm
blood diverted away from the intestine and to muscles
glycogen changed to glucose and released into the blood
pupils dilate
body hair stands upright
mental awareness increased
what is diabetes
where the pancreas cant make enough insulin to keep blood sugar level constant
what is diabetes
where the pancreas can’t make enough insulin to keep blood sugar level constant
what is homeostasis
keeping internal body conditions constant
what is tissue fluid
a watery solution of salts, glucose and other solutes. surrounds all c ells of the body, forming a pathway for the transfer of nutrients between the blood and the cells. formed by leakage from blood capillaries.
what is kept the same in the body
water salts level of carbon dioxide blood pH conc of dissovled glucose
solutes in urine
urea ammonia other nitrogenous waste sodium chloride (salt) potassium phosphate
excretory products of the skin
Sweat glands in the skin produce sweat. The water in sweat helps to keep the body cool in hot conditions, and it contains salts and urea.
excretory products of the lungs
Excess carbon dioxide and some water vapour are removed through the lungs when humans breathe out.
excretory products of the kidneys
The kidneys are organs of the urinary system - which removes excess water, salts and urea.
what does homeothermic mean
warm-blooded
if a mammal is homeothermic what does it mean
they keep their body temp constant regardless of the temp of their surroundings
advantages of a constant internal body temp
chemical reactions can take place at a steady rate,
metablolism doesnt slow down in cold environmens
where is the body’s thermoregulatory centre.
in the hypothalamus
functions of skin
tough outer later to resist damage
acting as a barrier to the entry of pathogens
forming an impermeable surface, preventing loss of water
acting as a sense organ for touch and temp changes
controlling loss of heat through body surface.
outer epidermis of skin
consists of dead cells that stop water loss and protect the body from microorganisms
hypodermis of skin
fatty tissue for insulation and store of energy (bottom layer)
dermis of skin
contains many sensory receptors. location of sweat glands and many small blood vessels as well as hair follicles.
changes in the body to respond to a rise in temperature
sweat glands produce sweat that (when evaporated from surface of skin) is cooling
hairs on the surface of the skin lie flat (it would otherwise trap heat)
vasodilation, the ateriorles dilate and blood flows through the capillary loops nearer the surface of the skin. so heat will be lost
what is the latent heat of vapourisation
the energy needed for a liquid to be evaporated and turn into a gas
changes in the body to a drop in temperature
vasoconstriction, the ateriorles leading to the surface of the capillary loops constrict so less heat energy is lost.
shivering generates heat
hair sticks up to trap heat
sexual reproduction
two specialised sex cells called gametes. one is a mobile male gamete (sperm) and one is a stationary female gamete (egg/ovum)
asexual reproduction
no specialised gametes, and no fertilisation, instead cells in one part of the body divide by mitosis to form a structure that breaks away from the parent body and grows into a new organism
fertilisation
the sperm must move to the egg and fuse with it. this forms a zygote, which will divide many times by mitosis to form all the cells of a new animal
if all the cells of the new indiviual are formed from just one cell in the body of the adult what willhappen
the offspring will be identical - they have exactly the same genes, and will all be genetic copies
gene def
a section of DNA that determines a paticular characteristic or feature.
when is asexual reproduction useful
in a stable envrionment where there istn much change. a large change could negatively impact the entire species (as theyre all genetic copies)
stages in sexual reproduction
gametes (sperm and egg are produced)
male gamete (sperm) is transferred to the female gamete (egg)
fertilisation
zygote formed develops into a new indiviual
why do offspring produced by sexual reproduction show a great deal of genetic variation
theyre a result of both gamete production and fertilisation
where is sperm produced
testes
where are eggs produced
ovaries
how are the gametes produced
when cells inside the sex organs divide by meiosis which produces cells which are not genetically identical and only half the number of chromosomes at the orginal cell
cells with the full number of chromosomes are called
diploid cells
cells with only half the number of chromosomes are called
haploid cells
how are sperm specialised for swiming
they have a tail like flagellum
what is external fertilisation
when females release their eggs into the water and the sperm swim through the water to fertilise the eggs.
what is internal fertilisation
where fertilisation takes place inside the females body
how many chromosomes will the zygot have
each gamete has half the chromosomes (23) so the zygote will have 46
how many chromosomes will the zygote have
each gamete has half the chromosomes (23) so the zygote will have 46
human life cycle
adult gametes meiosis fertilisation mitosis baby
ovulation
each month an egg is released into an oviduct from one of the ovaries. (this oviduct is known as the fallopian tube)
purpose of placenta
to allow the embryo to obtain nutrients and oxygen from the mothers blood and get rid of waste products like urea and carbon dioxide, and anchors the embryo in the uterus. it also secrets progesterone which maintian the prefnancy and prevent the embryo from being rejected from mothers body
where does the embryo grow
uterus
what is the amnion
a membrane that encoles the developing embryo
what does the amnion secrete
amniotic fluid which protects the developing embryo against sudden movements and bumps/
the 3 stages to the birth of a child
dilation of the cervix
delivery of baby
delivery of the afterbirth
what does puberty involce
gametes start to mature and be released
bodies of both sexes adapt to allow reproduction to take place.
these are started by the hormones released in the pituiutary gland called FSH and LH
what does FSH do in boys
stimulate sperm production
what does LH do in boys
secrete testosterone which controls the development of the male secondary sexual characteristcs.
male secondary sexual characteristics
sperm production
growth and development of male sexual organs
growth of armpit and pubic hair and facial hair
increase in body mass
voice breaks
female secondary sexual characteristics
the menstrual cycle begins, eggs released every month.
growth and development of female sexual organs
growth of armpit and pubic hair
increase in body mass and hips
voice deepens
breasts develop
what happens in the middle of the menstrual cycle
ovulation
day 1-5 in the menstrual cycle
menstruation
day 6-14 in the menstrual cycle
new uterus lining develops
day 14-28 in the menstrual cycle
egg in oviduct and blood supply develops in the new uterus lining
what is a follicle
one of the hundreds of thousands of cells inside an ovary develops into a mature egg.
what causes ovulation
a peak of LH
where does fertilisation take place
oviduct
what is the corpus luteum
the remainder of the follicle after fertilisation
what does progesterone do
maintains and thickens uterus lining, ready for the development of an embryo
if the egg is not fertilised what happens
menstruation
where does blood transport oxygen
from the lungs to everywhere else
where does blood transport carbon dioxide
everywhere to the lungs
where does blood transport nutrients
from gut to everywhere else
where does blood transport urea
from liver to kidneys
suggest a property that the tendons (located inside a penguins body) that operate the feet have (2)
strong and not elastic
what organ does hepatitis affect (1)
the liver
what organ involves diabetes (1)
the pancreas
describe the role of liver in digestion (2)
produces bile
which emulsifies lipids from large drops to small
neutralises the acid from the stomach and provides the optimum pH for the enzymes in the small intestine.
use your knowledge of osmosis to explain why the mass of each cube increased.
water molecules outside the potato of higher water potential and are more dilute go down the concentration gradient to a more concentrated solution of water inside the potato.
state the purpose of respiration
transfer of energy from glucose
give two differences between aerobic and anerobic respiration
- aerobic uses oxygen, anaerobic does not
2. anaerobic produces lactic acid, aerobic does not.
sugggest two reasons why anerobic respiration in humans is not efficent over long periods of time
transfers much less energy
lactic acid builds up in muscles, causing pain/cramp
which vitamin is needed to prevent scurvy
vitamin C
role of the intestine
absorb all the excess water from food
function of the pancreas
produce protease, amylase, and lipase enzymes
how does peristalsis move food through the gut
circular muscle around the gut contracts in waves to squeeze food through the gut.
what nutrients should a balanced diet contain (7)
carbohydrate protein lipid vitamins minerals water dietary fibre
what is the vitreous humour
the transparent gelatinous tissue filling the eyeball behind the lens
vitreous humour function
helps to hold the special shape
choroid function
provide nourishment to the outer layers of the retina through blood vessels
fovea function
responsible for sharp central vision
optic nerve function
transfrer visual info from the retina to the vision centres of the brain via electrical impulses
lens function
changes the focal distance of the eye
iris function
controls pupil size
cilliary muscle function
enables the lens to change shape for focussing
pupil function
allows light to enter the eye
cornea function
controls and focusses entry of light
blind spot functoin
where the optic nerve and blood vessels leave the eye
retina function
recieve light and convert it to neural signals and send that to the brain
suspensory ligament function
to support the eye
aqueous humour function
nourishing the cornea and lens
sclera functon
protect the eye
what is the aqueous humour
the clear fluid filling the space in the front of the eyeball between the lens and the cornea
how to measure the energy content of a food smple
- weigh food sample
- put 20cmcubed water in a boiling tube, and the tube supported in a clamp or stand. record temp of water
- the food is speared on the end of a mounted needle and then held in a bunsen burner flame until it catches fire.
- when the food is alight, themounted needle is used to hold it under the boiling tube, so the flame heats up the water.
- repeat if food goes out until it will no longer burn.
- measure final temp of water using the thermometer to stir gently.
then use the equation:
energy in joules per gram =
(final temp - inital temp) x 20 x 4.2
————————————————————–
mass of food
energy in joules per gram =
mass of food
what are memory cells
lymphocytes that dont get involved in killing microorganisms straight away. they remain in the blood for many years, sometimes a lifetime.
what do memory cells do
if the same microorganism re-infects a person, the memory lymphocytes start to reproduce and produce antibodies, so that the pathogen can be quickly dealt with. this is known as immunity
which is faster/more effective the first or secondary immune response
secondary. the number of antibodies in the blood can quickly rise, killing microorganisms before they have a chance to multiply to the point where they would cause disease.
what is a vaccination
where someone is injected with an agent that carries the same antigens as a specific pathogen. lymphocyted recognise the antigens and multiply exactly as if that microorganism had entered the bloodstream. they produce memory cells and the person is now immune. antibody production is faster, and in greater quantity than without the vaccination and may be enough to prevent the pathogen reproducing in the body and causing disease.
agents used as vaccines:
weakened strain of actual microorganism dead microorganisms modified toxins of the bacteria just the antigens themselves harmless bacteria genetically engineeered to carry the antigens of a different disease-causing microorganism.
what are platelts
fragments of large cells made in the bone marrow. if the skin is cut, exposure to the air stimulates the platelets and damaged tissue to produce a chemical.
what does fibrin
forms a network around the wound in which red blood cells become trapped. this forms a clot whcih orevents further loss of blood and entry of microorganisms that may be pathogens. the clot develops into a scab, which protects the damaged tissue while new skin grows.
purpose of the chemical produced by platelets
this chemical causes the soluble plasma protein fibrinogen to change into insoluble fibres of another protein, fibrin.
how is the kidney supplied with blood
through the renal artery, at a high pressure
where does the renal artery lead from
the aorta
what happens to the blood as it enters and leaves the kidney
it is filtered, and the cleaned blood passes out through each renal veinto the main vein or vena cava.
where does urine leave the kidney
the ureters, and is stored in a muscular bag called the bladder
what tube links the kidney to the outside
the urethra
what are the muscles in the urethra
the sphincter muscles
what do the sphincter muscles do
contract to close the urethra and hold back the urine. t
lower sphincter muscle
under conscious control
upper sphincter muscle
involuntary, automatically relaxes when bladder is full
what is the outside of the kidney
cortex
what is just below the cortex
medulla
what does the cortex contain
many tiny blood vessels that branch from the renal artery. many microscopic tubes that are not blood vessels. they are filtering units called kidney tubules or nephrons.
where do nephrons go
they run down from the cortex through the medella tp the bulges called pyramids. (the tubules eventually join up and lead to the tips of these pyramids) where they empty urine into a funnel like structure called the pelvis. it connects with the ureter, carrying the urine to the bladder.
where does blood filtering take place
bowman’s capsule
what does the bowmans capsule surround
glomerulus
explain the process of ultrafilteration
high pressure blood flows from the glomerulus through an arteriole to the capillaries next to bowmans capsule. due to this high pressure, fluid is forced from the blood through the walls of the capillaries and the bowman’s capsule into the space in the middle of the capsule. the fluid is now separated from the glomerulus by a capillary wall, basement membrane and cell wall of the capsule. the fluid is then filtered by the basement membrane which is not made of cells. it allows waterm ions and small molecules like glucose and urea (this is the glomerular filtrate) through but not proteins or large molecules like protein.
what separates the glomerulus and the bowmans capsule
the cells of the capillary wall
the basement membrane
the cell wall of the bowmans capsule
what is included in the glomerular filtrate
water, ions and small molecules like glucose and urea
what is not included in the glomerular filtrate
blood and large molecules like proteins
how much of the urine is retained in the body
99%
what does the loop of henle do
ut is involved with concentrating the fluid in the tubule by causing more water to be reabsorbed into the blood. the longer the loop of henle, the more concentrated urine will be.
what does ADH control
the permeability of the nephron
where is ADH produced
the pituitary gland
if there is a loss of water then the blood becomes very concentrated…
blood concentration increases
this is detected by receptor cells in a region of the brain called the hypothalamus, above the pituitary gland. these cells are sensitive to solute conc of the blood and cause the pituitary gland to release more ADH.
the ADH travels in the bloodstream to the kidney.
at the kidney tubules it causes the collecting ducts to become more permeable to water, so that more water is reabsorbed back into the blood.
this means the urine is more concentrated, and the body loses less water, and the blood becomes more dilute.
if the blood has too much water then it becomes very dilute…
blood concentration decreases.
this is detected by receptor cells in a region of the brain called the hypothalamus, above the pituitary gland. these cells are sensitive to solute conc of the blood and cause the pituitary gland to release less ADH.
this makes the kidney less permeable to water, so that less water is reabsorbed into the blood.
this means the urine is less concentrated, and the body loses more water, and blood becomes less dilute.
what is negative feedback
when a change in conditions in the body is detected and a process is started that works to return conditions to normal. when the conditions are returned to normal, the corrective process is switched off.
what happens when water content of the blood returns to normal
this acts as a signal to switch off the release of ADH, the feedback pathway itnforms a closed loop.
what does FSH do
FSH: stimulates egg development and oestrogen, secretion in females and sperm production in males
what does LH do
egg release in females and testosterone production in males,
what does ADH do
controls the water content of the blood
describe the role of the placenta in the development of the embryo
DIFFUSION takes place to allow the embryo to obtain GLUCOSE/OXYGEN, which it can use for RESPIRATION. it can get VITAMINS and AMINO ACIDS (via active transport?) and transfer away waste products like carbon dioxide and UREA.
