Studied by 15 peoplewhat are tissues?
groups of similar cells that act together to perform a similar function
what are organs?
groups of distinct tissues that work together to perform a specific function
what is an organ system?
groups of organs that work together to perform a particular role
what organs are in the digestive system?
large intestine
stomach
liver
small intestine
glands
what do enzymes do?
increase the speed of reactions
what happens on an enzyme?
the substrate (reacting chemical) must bind to the enzyme’s active site (will only fit specific substrates)
what factors affect the rate of enzyme action?
pH
temperature
where are digestive enzymes made?
in the glands and the lining of the gut
what are digestive enzymes used for?
breaking down large food molecules
what breaks down starch?
amylase
where is amylase produced?
small intestine
pancreas
salivary glands
what is amylase’s purpose?
it breaks down starch into its constituent simple sugars (predominantly maltose)
what are amylase’s sites of action?
small intestine
mouth
what breaks down proteins into amino acids?
proteases
what are protease’s sites of action?
small intestine
stomach
where are proteases produced?
small intestine
pancreas
stomach
what breaks down lipids into glycerol and fatty acids?
lipase
where is lipase produced?
small intestine
pancreas
what is bile?
an alkaline substance that is stored in the gall bladder after having been produced in the liver
why is bile important?
neutralises stomach acid to stop enzymes in the small intestine becoming denatured
emulsifies (breaks up) fat into tiny droplets so they have higher SA and increases the rate of reactions that breaks fat down
how do you test for lipids?
add sudan III
red stained oil layer = present
how do you test for starch?
add iodine solution
blue-black = present
how do you test for sugar?
add benedict’s reagent and heat for 2 minutes
green/yellow/red = present
how do you test for proteins?
add biuret solution
mauve/purple = present
what adaptations do arteries have?
elastic fibres allowing them to stretch and spring back
thick muscle walls to cope under high pressure
what do capillaries do?
food and oxygen moves out of the blood and into the cells and waste products (such as CO2) move out of the cells and into the blood
what are veins?
they form when capillaries join up after passing through the body
what kind of blood do veins transport?
deoxygenated EXCEPT pulmonary vein from the organs back to the heart
what adaptations do veins have?
thinner walls because of lower pressure
wider cross section than arteries to counteract the low pressure hindering blood flow
valves to prevent the backflow of blood
what makes the heart pump?
a group of cells in the right atrium act as a pacemaker
what happens when a heart beats?
blood enters the heart via the atria
the atria contract and force blood into the ventricles
the ventricles contract and force blood to exit the heart
what happens in the vena cava?
the heart receives deoxygenated blood from the body
what happens in the pulmonary vein?
the heart receives oxygenated blood from the lungs
what happens in the aorta?
the heart pumps out oxygenated blood to the body
what happens in the pulmonary artery?
the heart pumps out deoxygenated blood to the lungs
what happens in the coronary arteries?
supply the heart muscle with oxygenated blood
why is it called the double circulatory system?
the blood passes through the heart twice per circuit?
what happens in the circulatory system?
deoxygenated blood from the body enters into the right atrium of the heart
this blood is pumped out of the heart and towards the lungs by the right ventricle
the deoxygenated blood exchanges CO2 for oxygen and the blood becomes oxygenated
the blood returns to the left atrium of the heart
the blood is pumped out of the heart and to the body by the left ventricle through the aorta
the blood returns to the heart
where does oxygenation of the blood take place in mammals?
in the lungs
what do alveoli do?
they allow oxygen and carbon dioxide to be exchanged between the blood in the capillaries and the air in the lungs by diffusion
what are alveoli?
tiny air sacs in the lungs
how are alveoli adapted for efficiently exchanging substances?
large surface area
surrounded by capillaries so they have a rich oxygen supply and the distance for gases to diffuse is small
what is blood made up of?
a fluid called plasma
what is plasma made of?
platelets
white blood cells
red blood cells
what do platelets do?
they are responsible for triggering blood clotting at the sites of wounds and have no nucleus
what do red blood cells do?
transport oxygen from the lungs to all body cells
how are red blood ells adapted?
haemoglobin - binds with oxygen in the lungs and carries this around the blood before releasing it to the body cells to be used in respiration
no nucleus - more room for haemoglobin and oxygen
small size to pass through tiny capillaries
bioconcave shape to create a large surface areas and allow for rapid diffusion of oxygen
what do white blood cells do?
defend against infections
what adaptations do white blood cells have?
no nucleus
can change shape to squeeze through walls of blood vessels into body tissues and to engulf harmful microorganisms
what is health?
a description of an individual’s physical and mental well-being
what is a communicable disease?
a disease that can be spread between organisms
what is a non-communicable disease?
a disease that cannot be spread between organisms
what does HIV suppress?
the immune system - making individuals more susceptible to catching other infectious diseases
what can allergies be triggered by?
an immune reaction to a pathogen
what is a risk factor?
factors that increase the probability of developing a disease
what are the categories of risk factors?
lifestyle and substances
what are examples of links between risk factors and disease?
poor diet, smoking and lack of exercise - cardiovascular disease
excessive alcohol consumption during pregnancy - brain damage
excessive alcohol consumption - liver and brain damage
exposure to ionising radiation - cancer
smoking - low birth weight of babies
smoking - lung disease
obesity - type 2 diabetes
what is coronary heart disease?
a non-communicable disease where the coronary arteries become narrower because of a build up of fatty deposits which reduces blood flow and leads to a lack of oxygen to the heart
what is heart valve disease?
where valves can become faulty, either by leaking or being unable to fully open
what effect does having leaky valves have?
it allows the backflow of blood which forces your heart to do more work to circulate the same volume of blood qand creates a strain on the heart
what is the effect of having valves that do not fully open?
they will obstruct blood flow and a greater force is required to force the blood through the body which adds to the strain of the heart
how can faulty valves be fixed?
by inserting either animal or artificial valves
what are the benefits of artificial hearts?
unlikely to be rejected by the patient’s immune system so no immunosuppressant drugs are necessary
can be used to provide the heart with rest to allow it to recover
what are the drawbacks of artificial hearts?
can result in long and expensive stays in hospital
can cause blood clotting - strokes
what are the two common treatments for coronary heart disease?
stents and statins
what are the benefits of stents?
they keep coronary arties open
what are the drawbacks of stents?
irritation from the stent causes artery to narrow again as scar tissue builds up
drugs must be taken to prevent blood clotting on the stent
what are statins?
drugs that can be taken to decrease blood cholesterol levels and slows down the build up of fatty materials
what are the advantages of drugs to treat heart disease?
often cheap to buy
no surgery required
what are the disadvantages of drugs to treat heart disease?
may have side effects
patient must remember to take them
what are the advantages of using mechanical devices to treat heart disease?
used in cases where a donor organ is not available
what are the disadvantages of using mechanical devices for heart disease?
require a power supply
may eventually wear out and need replacing
what are the advantages of using heart transplants to treat heart disease?
successfully transplanted organs won’t wear down
will function like replaced organ
what are the disadvantages of heart transplants to treat heart disease?
require a suitable donor
need immunosuppressants
increases risk of different disease
what are malignant tumours?
they can invade neighbouring tissues and spread throughout the body in the blood, leading to the creation of more secondary tumours
what are benign tumours?
they stay in a specific part of the body, often within a membrane
what are the cancer risk factors?
lifestyle e.g. smoking, obesity, UV exposure
genetic
what are examples of plant organs?
stems
leaves
roots
reproductive structures
what is transpiration?
transports water and the minerals dissolved in it through the plant
what are the factors affecting the rate of transpiration?
air flow
humidity
light intensity
temperature
what is translocation?
the process by which food in photosynthesis is transported from the leaves to the growing regions of plants and storage organs
what happens in phloem tubes?
translocation
what is transported in xylem vessels?
water and minerals
what strengthens the cell wall of xylem?
lignin
how do root hair cells absorb water form the soil?
via osmosis
what adaptations do root hair cells have?
lots of mitochondria to ensure enough energy for active transport
long projections increase surface area
what are stomata?
gaps in the lower epidermis of the leaves that facilitate the diffusion of gases including evaporated water in and our of the leaf
what opens and closes the stomata?
guard cells
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