Flashcards in Topic 1 - Control Systems Deck (74):
What are the three main roles of the Kidney
Removal or urea from the blood. Urea is produced in the liver from the breakdown of excess amino acids
Adjustment of iron levels in the blood
Adjustment of water content of the blood
How do the kidneys work
They filter stuff out of the blood under high pressure and then reabsorb the useful things. The end product is urine
what are the filtration units in the kidneys
How does ultrafiltration in the kidneys happen
High pressure is built up which squeezes water, urea, ions, and glucose out of the blood and into the bowman capsule.
The glomerulus and the bowman capsule act like filters so big molecules like proteins and blood cells stay in the blood.
How does Reabsorption happen in the Kidneys?
as liquid flows along the nephron useful substances are reabsorbed:
All glucose is selectively reabsorbed, moved out of the nephron back into the blood against the concentration gradient.
Sufficient water is reabsorbed according to the level of ADH. Osmoregulation.
What substances are not reabsorbed and what happens to them?
Urea and excess water. They continue out of the nephron, into the ureter and down the bladder as urine. Urine is released through the urethra.
What hormone controls the amount of water reabsorbed by the kidney
anti-diuretic hormone (ADH)
Which gland releases ADH
what is negative feedback
where changes in the environment trigger a response that counteracts the changes meaning the internal environment tends to stay around the norm.
What happens if you are dehydrated?
The brain detects water loss
Pituitary gland releases more ADH
ADH makes kidney reabsorb more water
Return to hydrated
What happens if there is water gain?
Brain detects water gain
pituitary gland releases less ADH
Lack of ADH means kidney reabsorbs less water.
Return to hydrated
what is a dialysis machine
patients who have kidney failure can't filter their blood properly so i dialysis machine can do it for them.
what is in dialysis fluid?
a glucose concentration similar to a normal level in the blood
a concentration of ions similar to that found in normal blood plasma
How does dialysis work?
Dirty’ blood (high in urea) is taken from a blood vessel in the arm, mixed with blood thinners to prevent clotting, and pumped into the machine. Inside the machine - separated by a partially permeable membrane the blood flows in the opposite direction to dialysis fluid, allowing exchange to occur between the two where a concentration gradient exists
What is the only cure for kidney disease
What can happen to transplanted kidneys?
they can be rejected, treated like a foreign body, and attacked by antibodies. To prevent this a donor with a tissue type that closely match the patient is chosen and the patient is treated with drugs that surprise the immune system so the immune system won't attack it.
what are the main functions of egg cells
to carry the female DNA and to nourish the developing embryo in the early stages.
what are the specialised features of egg cells
contains nutrients in the cytoplasm to feed embryo
straight after fertilisation the eggs membrane changes its structure to stop and more sperm getting in, this makes sure the offspring ends up with the right amount of DNA.
Haploid nucleus, this is so that when the egg is fertilised, the resulting cell will have the right number of chromosomes.
What is the function of sperm cells
to transport the males DNA to the females egg so that their DNA can combine
what are the specialised features of sperm cells
small and have long tails so they can swim
lots of mitochondria in their middle section to provide energy needed to swim the distance
have an acrosome at the front of their head where they store enzymes needed to digest way through the egg membrane.
What are the four stages of the menstrual cycle
stage 1 - Day 1 is when bleeding starts. Uterus lining breaks down and is released.
Stage 2 - Day 4-14.The lining of the uterus builds up again into a thick spongy layer of blood vessels ready to receive a fertilised egg.
Stage 3 - Day 14. The egg is released from the ovary (ovulation)
Stage 4 - Day 14-28. The lining is then maintained for about 14 days. If no fertilised egg has landed on the uterus wall by day 28 then the spongy lining starts to break down again and the whole cycle starts again.
What four hormones are involved in menstruation
follicle-stimulating hormone (FSH)
Luteinising hormone (LH)
What does FSH do
causes a follicle (egg and its surrounding cells) to mature in one of the ovaries
Stimulates oestrogen production
what does Oestrogen do
causes the lining of the uterus to thicken and grow.
High level stimulates LH surge
What does LH do
LH surge stimulates ovulation at day 14 the follicle ruptures and the egg is released.
Stimulates the remains of the follicle to develop into a structure called corpus luteum which secretes progesterone
What does progesterone do?
maintains lining of the uterus
inhibits the production of FSH and LH
when levels of progesterone falls, and theres a low oestrogen level the uterus lining breaks down,
Low progesterone level allows FSH to increase and then the whole cycle starts again
What happens if the egg is fertilised
the level of progesterone will stay high to maintain the lining of the uterus during pregnancy.
What is the uterus lining made of
thick spongey layer of blood vessels - this blood supply allows the placenta to develop.
what does the placenta do
supplies the baby with the oxygen, glucose, and nutrients it needs to grow and removes waste products like urea and carbon dioxide
How can hormones be used to increase fertility
some women have low levels of FSH so eggs can't mature so are not released. You can inject FSH and LH to stimulate egg release
What are the advantages and disadvantages of using hormones to increase fertility
+ it helps a lot of women to get pregnant
- it doesn't always work and it is expensive to keep trying
- increases chance of multiple births which can lead to complications
How does IVF work
In vitro fertilisation involves fertilising woman eggs with mans sperm in a lab where it grows into an embryo. Once embryos are tiny balls of cells one of two are transferred to woman uterus to improve chances of pregnancy. FSH and LH are given before egg collection to stimulate egg production (so more than one egg can be collected)
What are the pros and cons of IVF
+ Can give infertile couple a child
- Some women have strong reaction to hormones e.g abdominal pain, vomiting
- Some reports of increased risk of cancer (not clear if true)
- Multiple births can happen which are risky for mother and babies
What are the pros and cons of IVF with donated eggs
+ Women who can't produce eggs can have baby
+ can prevent risk of passing on genetic disease
- emotionally difficult for the family
What are surrogate mothers
if a women can't become pregnant she might ask another woman to carry baby for her
ivf is used to produce embryo then implanted into surrogate mother
after giving birth baby goes to genetic parents
pros and cons of surrogate mothers
+ allows couple to have children if medical problems mean mother can't get pregnant or its risky to give birth
- surrogate is legally the mother until its adopted by genetic parents. She has the right to keep the child.
What decides whether you are male of female
23rd pair of chromosome
What is the allele pair for males
what is the allele pair for females
How are some characteristics sex-linked
If the allele code for it is located on a sex chromosome
the y chromosome is smaller than X so carries fewer genes. Most genes on the sex chromosome are only carried on X chromosome,
Men only have one X chromosome so sometimes only have one allele for the characteristic so it is shown even if it is recessive making men more likely to show recessive characteristics than women.
Give an example of a sex linked genetic disorder
Colour blindness or haemophilia (where blood doesn't clot properly)
What allele is colour blindness caused by
faulty allele carried by X chromosome. Recessive
How is the rate of growth of bacteria described
Exponential. the number of bacteria doubles at regular intervals.
How did people used to think disease was caused
they thought diseases spontaneously appeared
Who was the scientist to offer an explanation for how disease is caused
What did Louis Pasteur think disease is caused by
he thought there were microbes in air that cause disease and decomposition
What experiments did Louis Pasteur do to prove his theories
He heated broth in two flasks then left them open.
One flask had a curved neck so bacteria in air would settle in the loop and not get to the broth.
The curved neck broth stayed fresh but the other didn't. This showed it was the microbes (in air) causing it to go off.
What did Pasteur later invent
the process of pasteurisation.
This involves heating something up to 70*C and then cooling it, killing most harmful germs so the product won't make you ill.
What are processes that reduce contamination called
What is pasteurisation used for and why is it preferable to sterilisation
used to treat raw milk to kill harmful bacteria so it is safe to drink
sterilising involves more severe form of heat treatment which kills everything but makes the milk taste funny and destroys some of the vitamins
How can you investigate microorganism growth
use resazurin which is a dye that is sensitive to oxygen so as more microorganisms respire and use up oxygen the dye changes from blue to lilac to mauve to pink to colourless.
this means you can use it to see the effects of temperature or pH on the growth of bacteria
What system fights microorganisms
Which part of the immune system is the most important
white blood cells
What do white blood cells do
travel round the body in blood and patrol for microorganisms.
What do B-lymphocytes do
when they come across an invading microorganism they respond by producing antibodies.
Every pathogen has unique molecules on the surface of its cells called antigens - no two species have the same ones
When B-lymphocytes come across a foreign antigen they start to produce proteins called antibodies which bind to and kill the invading cells. The antibodies produced are specific to that pathogen so won't work with other pathogens.
Antibodies are then produced rapidly and flow all round the body to call all similar bacteria or viruses
What are memory lymphocytes
When a pathogen enters for the first time the response is slow because there aren't as many B-lymphocytes that can make the antibody.
Eventually enough of the right antibody is produced but the infected person might show some of the symptoms.
After being exposed to an antigen a special type of B-lymphocyte is produced called memory lymphocyte which remains in the body for a long time and will remember the antibody.
If the same pathogen enters the body again the immune system will produce a quicker, stronger response so no symptoms will be shown.
How does immunisation work
involves injecting dead or inactive microorganisms into the body which are antigenic so even though they are harmless the body will produce the antigens to attack them which triggers memory lymphocytes to grow so if the pathogen enters the body then it will be immediately killed.
How was the first vaccine invented
Edward Jenner invented the first vaccine which worked against smallpox.
He noticed that people with cowpox didn't get smallpox.
He took bits of a scab from a girl with cowpox and but them into a cut on another boy. The boy was a bit unwell but then recovered. When exposed to smallpox the boy was not infected.
The cowpox antigens are the same as smallpox so the memory lymphocytes could fight the disease.
What are the pros and cons of immunisation
+ Big outbreaks of diseases (epidemics) can be prevented if a large percentage of the population are immunised. There are fewer people to pass the disease to.
+ some diseases such as smallpox have been virtually wiped out
- They don't always work
- You can have a bad reaction to a vaccine e.g swelling or fever or seizures but bad reactions are very rare
How are monoclonal antibodies produced?
B-lymphocytes don't divide easily but tumour cells divide lots and can be grown easily
Antigen is injected into a mouse and the b-lymphocytes are then taken from it.
They are fused with a tumour cell to create a hybridoma.
the hybridoma divides quickly to produce lots of identical antibodies called monoclonal antibodies.
What are monoclonal antibodies used for?
diagnosis of cancer
treatment of cancer
find blood clots
how are monoclonal antibodies used in pregnancy tests?
hormone in urine only found when a woman is pregnant. pregnancy testing sticks detect the hormone.
The bit of the stick you wee on has antibodies to the hormone with blue beads attached.
the test strip has more antibodies to the hormone stuck onto it so they can't move
if you're pregnant the hormone binds to the antibodies on the blue beads. the urine moves up the stick carrying the hormone and the beads. the beads and hormone bind to the antibodies so the blue beads get stuck turning it blue.
How are monoclonal antibodies used to detect cancer
antibodies are labelled with a radioactive element
labelled antibodies are given to patient through a drip, they go into blood and are carried round the body.
when they come into contact with cancer cells they bind to the tumour markers
a picture of patients body is taken with special camera and detects radioactivity. anywhere cancer cells are will be brighter.
doctors can tell where cancer is, what size it is, and if its spreading
How are monoclonal antibodies used to treat cancer
anti-cancer drug is attached to monoclonal antibodies
antibodies are given to the patient through drip
antibodies target specific cells because they only bind to tumour markers
the drug kills cancer cells but doesn't kill normal body cells near the tumour
other treatments affect other cells
side effects lower than for other drugs or radiotherapy
How are monoclonal antibodies used to find blood clots
when blood clots, proteins in the blood join together to make solid mesh.
Monoclonal antibodies have been developed that bind to the proteins.
if you attach radioactive element to antibodies you can take picture using special camera that picks up radiation and is bright where blood is clotted.
Where do many drugs come from
plants, they produce a variety of chemicals to defend themselves against pests and pathogens. These chemicals can be used in drugs to treat human diseases or relieve symptoms.
Give three examples of drugs from plants
Aspirin - used to treat pain and lower fever. Developed from chemical in leaves and bark of willow trees
Taxol - anti cancer drug. Comes from pacific yellow tree, discovered when scientists were screening loads of plants looking for potential treatments
Quinine - comes from south america cinchona tree. For years it was used as main treatment against malaria.
How do different pests reduce crop yield?
fruit flies - feed on fruit and can ruin entire fruit crops
weeds - compete with plants for nutrients in the soil. If there are fewer nutrients the plants won't grow as well and the crop yield will be lower
Pathogens - some energy is taken by the pathogen or used to replace bits that have been killed meaning less energy is used to make the crop so yield is lower. Heavy infestation can mean whole field of plants produce no food at all.
What is a photoperiodic response?
response to change in the amount of light and dark in a 24 hour period.
How are plants photoperiodic
some plants only germinate, grow, or flower given a certain amount of light. these responses make sure they grow or reproduce at the time of year that best suits them.
Give some examples of photoperiodic plants
seeds of some artic plants only germinate if the days are very long so only in the middle of summer.
Some plant buds use the increasing day length to tell them that its far enough away from winter to grow so they won't be killed by frost.
Some plants only flower when the day is at least a certain length to make sure they flower near to summer.
Some plants only flower when the days are less than a certain length to make sure they flower in the early spring or autumn so they only flower when the right insects are about to pollinate the flowers.
What are circadian rhythms
biological processes that follow a 24 hour cycle. They include chemical patterns, physiological patterns, and patterns of behaviour. Animals, plants and microorganisms all have circadian rhythms. They are controlled internally but influenced by environmental factors like light intensity.
Give two examples of circadian rhythms in animals
sleep - the body's master clock gets information about light intensity from your eyes and controls the production of melatonin which makes you sleepy. When it gets dark you melatonin production increases. Having regular sleep patterns is good for your health and helps you feel awake at the right times.
Urine production - Body's master clock also controls production of ADH. At night ADH levels increase which reduces urine production so sleep isn't interrupted