Flashcards in B3 Deck (45):
What are the three main roles of the kidneys?
removal of urea from the blood, which is produced in the liver from the breakdown of amino acids
Adjustment of ion levels in the blood
Adjustment of water content of the blood
What is ultrafiltration?
High pressure is built up which squeezes water, urea, ions and glucose out of the blood and into the Bowmans capsule
Glomerulus and capsule act as filters , so big proteins and blood cells are not squeezed out, but stay in the blood.
What is reabsorption?
All glucose is selectively reabsorbed moved from the nephron to the blood against the concentration gradient
Sufficient water is also reabsorbed according to the level of ADH in the blood.
What is the release of waste?
Urea and excess water are not absorbed, they continue out of the nephron, into the ureter and down to the bladder, as urine, where it is released through the urethra.
What is a dialysis machine?
is used to filter the blood for someone who cannot do so themselves, has to be done regularly to keep dissolved substances at the right concentrations, and to remove waste.
How is kidney rejection prevented?
A donor is chosen with a type that closely matches the tissue of the patient chosen.
Patient is treated with drugs that suppress the immune system , so it won't attack the new kidney.
How does an egg cell have special features?
Contains nutrients in the cytoplasm to feed the embryo
After fertilisation, the membrane changes its structure to stop any more sperm entering. So offspring have the right amount of DNA.
Contains a haploid nucleus, so it has the right number of chromosomes
How are sperm adapted?
Small, with long tails so they can swim
Have lots of mitochondria in the middle section yo provide energy from respiration needed to swim the distance.
Have an acrosome at the front of the head, that contains enzymes to digest their way into the egg cell.
What are the four stages of the menstrual cycle?
Stage 1 - Day 1 bleeding starts, uterus lining breaks down and is released
Stage 2 - lining of the uterus builds up again, from day 4 to 14, into a thick spongy layer of blood vessels.
Stage 3 - egg is released at day 14
Stage 4 - lining is then maintained until day 28, and if no egg is fertilised then it breaks down and the cycle starts again
What are the four hormones of the menstrual cycle?
FSH (Follicle-stimulating hormone)
LH (Luteinising Hormone)
What does FSH do?
Causes an egg to mature in one of the ovaries
Stimulates oestrogen production
What does Oestrogen do?
Causes the lining of the uterus to thicken and grow
A high level of this stimulates an LH surge
What does LH do?
Stimulates ovulation and ruptures the egg casing so it is released.
Stimulates the remains of the egg casing to develop into a structure called corpus luteum, which secretes progesterone
What does Progesterone do?
maintains the lining of the uterus
inhibits LH and FSH
When both the oestrogen and progesterone levels fall, the lining breaks down
A low level of P allows FSh to increase and so the whole cycle starts again
How is FSH controlled by negative feedback?
FSH stimulates the ovary to release oestrogen, which inhibits further release of FSH, making it low, making sure no more eggs mature
What do low levels of FSH mean for women wanting to get pregnant?
too low means eggs can't mature and so no eggs are released and so cannot get pregnant
How can egg release be stimulated?
Injecting hormones FSH and LH
What are the pros and cons of injecting FSH and LH to get pregnant?
Helps a lot of women to get pregnant when they couldn't
It doesn't always work, so they have to do it many times which is expensive
Too many eggs could be stimulated and could result I unexpected multiple pregnancies
What is IVF
In vitro fertilisation , collects eggs from a women's ovaries and fertilises them in a lab using the man's sperm, and are then grown into embryos.
FSH and LH are given to stimulate egg growth
What are the pros and cons of IVF?
A child is possible
Some women have horrible side effects of hormones
Increased risk of cancer due to hormone treatment
multiple births can happen, meaning a greater risk of miscarriages
What are the pros and cons of donated eggs?
Allow women to have a baby
Can prevent passing on genetic disorders
It can be emotionally difficult for parents to raise a genetically different child
What are the pros and cons of a surrogate mother?
Allows a couple to have a child, if the mother cannot carry a child
Surrogate mother is legally the child's mother until it is adopted by the parents intended, she has the right to decide to keep the child
Bacteria produce by...
splitting in two
How did Pasteur show that microbes cause decay and disease?
Pasteur heated broth in two flasks, then left them open. One of the flasks had a curved neck so bacteria in the air would settle on the loop, and not get into the broth, and one did not, the curved stayed fresh. This showed it was the microbes and not the air that caused the broth to go off.
What is pasteurisation?
Heating something up to about 70degrees and then cooling it, killing off most of the harmful germs, so it shouldn't make you ill.
What is the name for any process you do to reduce contamination by germs?
How does your immune system deal with infectious microorganisms?
Immune system contains white blood cells, that patrol your body. some are a special type called B-lymphocytes, which respond by producing antibodies.
How do b-lymphocytes respond to invading microorganisms?
Every pathogen has unique molecules on its surface - called antigens.
When your b-lymphs come across a foreign antigen, they start to produce proteins called antibodies, which lock on to and kill the new invading cells, specific to the pathogen and not to any other. They flow quickly around the body to kill microorganisms.
What are memory lymphocytes?
Remain in the body for a long time, and 'remember' a specific antibody.
The person is now immune to pathogen. Meaning it will respond quickly the next time.
What is immunisation?
involves injecting a dead or inactive microorganisms into the body, They are harmless to the body but make the antibodies attack and fix to the antigens. They also trigger memory lymphocytes to be made.
How did Jenner use cowpox to safely immunise against smallpox?
Took bits of scab from a girl with cowpox, and put them into a cut on the arm of a boy. He was a bit unwell, but recovered. Then the boy was exposed to small pox, but he did not catch it.
Cowpox has the same sort of antigens as smallpox and so the boy was quickly produced antibodies to stop him getting it.
What are the pros and cons of immunisation?
Epidemics can be prevented, there are fewer people to pass on the disease, if many are immunised.
Some diseases have been completely wiped out by immunisation.
Doesn't always work, sometimes doesn't give full immunity.
Can sometimes have a bad reaction to vaccines, but are very rare.
How are monoclonal antibodies used in pregnancy tests?
The bit of the stick you urinate on has antibodies to the hormone that indicates pregnancy stuck to it, with blue beads attatched.
How are monoclonal antibodies used to diagnose cancer?
The antibodies are labelled with a radioactive element, then they are given to a patient through a drip, they are carried around the body in the blood. When the antibodies come into contact with the cancer cells they bind to the tumour markers, a picture of the patients body is taken using a special camera detecting radioactivity, showing cancer cells as a bright spot.
How are monoclonal antibodies used to target drugs to cancer cells?
Anti cancer drug is attached to monoclonal antibodies, given to a patient through a drip, they target the cancer cells because they only bind to tumour markers. The drug kills the cancer cells, but not the normal cells, unlike some treatments.
How are monoclonal antibodies used to find blood clots?
When blood clots, proteins in the blood join together to create a solid mesh. MA have been developed to bind to these proteins, and a radioactive element can be attached to them, injecting into the body to show up as a bright spot where the clots are.
What is aspirin?
Used to treat many types of pain, and to lower fever.
Developed from leaves and barks of the willow tree.
What is taxol?
comes from the bark of the yew tree
developed from the screening of plants to find a cure
What is Quinine?
south American cinchona tree
main treatment against malaria
How do different pests reduce crop yields?
Fruit flies feed on them, so can ruin crops
Weeds that grow near plants compete for nutrients in the soil, amount of crop will be reduced as they compete.
If a plant is infected by a pathogen, it takes some of the plants energy, reducing yield
How else do pests effect crops?
Increase costs, as more money is spent on pesticides, driving up the costs.
What is a photoperiodic response?
A response to a change in the amount of light and dark in a 24 hour cycle.
What are some examples of photoperiodic cycles in plants?
Some seeds of arctic plants only germinate if the days are long, i.e. the middle of summer.
Some plant buds use day lengths to determine whether it is far enough away from winter to germinate, so they are not killed by frost.
What are circadian rhythms?
biological processes that follow a 24 hour cycle
controlled internally but influenced by environmental factors