section b: animal physiology Flashcards
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.
