Control Systems Flashcards
What is a circadian rhythm
A biological rhythm that happens over 1 day
What is and what does a biological clock do
A timing mechanism in the brain that regulates what happens in our bodies over a 24 hour periods such as release of hormones
What are hormones
Chemical messengers that are made in the body and travel in the blood stream. They affect different parts of the body
What makes us tired
A hormone called melatonin and is released around ten pm and levels of it drop in the morning so we are more alert
How is the biological clock kept in sync
Exposure to day and night, this is why we get jet lag
Name two plant circadian rhythms and explain them
Flowers open in day and close at night to make sure they are ready for insects in during the day and protect pollen during the windy, cold and damp night
Nestor is only produced in the day when insects are around and more likely to visit
What is photoperiodism
The response to changing lengths of daylight
Give examples of photoperiodism
Seeds germinate when they sense longer day length, spring
Trees shed their leafs as daylight becomes less
What are alkaloids
Poisonous chemicals produced in leafs to protect them from pests
Why are poisons in plants only made at certain times
It uses lots of energy so producing them when there are no pests (night) would waste a lot of energy so they are only made during the day
What are pathogens
Organisms that cause disease such as potato blight
Give 3 examples of useful plant poisons and the plant they’re from
Digoxin found in foxgloves can cause heart attacks if too much is used but in small doses it can benefit the heart so is used to treat heart problems
Quinine is produced by cinchona trees and can treat malaria
Aspirin is produced in willow trees and can treat pain and fever
How and who discovered microorganisms caused disease
Louis Pasteur proved it by putting broth in a straight neck flask and a swan neck flask. The straight neck broth went bad after a few days, broth in swan neck stayed fresh for longer as microorganisms got trapped in the swan neck
What is the process of keeping things free from microorganisms
Aseptic techniques
Give an example of an aseptic technique
Pasteurisation involves heating the food such as milk before storing it to kill bacteria in it
How can the amount of bacteria in something be measured
Use resazurin dye that indicates oxygen levels. It’s blue when high oxygen levels and pink when they’re low. If there is lots of bacteria, lots of oxygen will be used up so it’ll be pink
What are antigens
Chemicals on the outer surface of all bacteria and cells
How does our immune system use antigens
Foreign antigens can be detected by the immune system which then destroys them and the foreign cells
What are antibodies
Chemicals that are released by lymphocytes that stick perfectly onto antigens and destroy the cell
How does a vaccine work
A weakened or dead pathogen is injected into the body. The body detects the foreign antigens and produces lymphocytes with antibodies that perfectly fit the foreign antigens. These then divide to make more and more of these lymphocytes with matching antibodies. Some of these lymphocytes release lots of the antibodies to destroy the foreign pathogen whilst others become memory lymphocytes that remain in the body so it can quickly respond if that pathogen ever re enters the body
Pros and cons of immunisation 3 each
Risks:
Person often gets swelling or redness around vaccination site
Some children may get a mild form of the disease they are being vaccinated against
Very rarely, the person may suffer and allergic reaction
Advantages:
Person becomes immune to disease without having to suffer from it
A lot lower chance of long lasting harm from diseased they are vaccinated against
If enough people are vaccinated, the disease becomes rare and even unvaccinated people are unlikely to get it
What is an infection
The entry of a pathogen into the body
What is the primary response to an infection and explain
The first time an a pathogen enters the body where only one or two lymphocytes recognise it so it takes a while for them to divide and release antibodies to destroy it. This is why it’s usually at least a few days before the infection goes away
What is the secondary response to an infection and explain
Where a pathogen enters the body but not for the first time so many memory lymphocytes recognise it and quickly divide and release antibodies so more often that not, the pathogen is destroyed before symptoms show
What are monoclonal antibodies
Many identical antibodies
What does a lymphocyte that makes antibodies called and what can’t it do
It becomes a B lymphocyte and can no longer divide
How can monoclonal antibodies be made in large quantities and what is the new cell called
By combining a B lymphocyte with a cancer cell so it can still divide many times whilst making antibodies. This is called a hybridoma
Give two uses of monoclonal antibodies and explain them
Antibodies that stick to a hormone called HGH is used in pregnancy tests as this hormone is released when the woman is pregnant so if the monoclonal antibodies stick to the hormone, there is a colour change
They can be made slightly radioactive and made to stick to thighs such as cancer cells so they can be detected with detectors to show where the cancer is
What are metabolic reactions
Reactions that take place in the body and produce waste products
Name two waste products, where they’re from and how they’re removed
Urea from liver cells made from excess amino acids. Removed from blood by being filtered by the kidneys
Carbon dioxide made from respiring cells and removed though the lungs
What do the kidneys do
Blood enters it though renal arteries where it is filtered and waste products such as urea is filtered out to form urine. The clean blood flows out of the renal veins
What happens in the urinary system
Dirty blood enters kidneys through renal arteries
Kidneys clean the dirty blood and form urine
Clean blood exits kidney through the renal vein
Urine goes through ureters from kidneys and into bladder
Urine exits body through urethra
Why are kidneys important
If they stop working, poisonous urea will build up in the blood and won’t be turned and removed as urine
What is the criteria for a kidney so it can be put into someone else and explain
Must be similar to patients cells as otherwise, immune system of patient will recognise the foreign antigens on the doner kidney and will destroy it
Must be healthy else no point.
What is and what does a dialysis machine do
It’s like an electric kidney, it cleans the blood if kidneys can’t do it. Someone without healthy kidneys may have to be connected to it for several hours several times a week
What are nephrons
Tiny microscopic tubes in kidneys
What are the parts of a nephron
Glomerulus Bowmans capsule Convulated tubes Loop of henlé Collecting duct
How does a nephron work
Blood from renal arteries enters network of capillaries ( glomerulus)
Gloerulus sits in bowman capsule which has lots of little wholes that filter out small molecules such as water, glucose and urea whilst larger molecules such as proteins and blood cells stay in the glomerulus
Some substances are réabsorbed through the nephron walls such as water and glucose ( selective reabsorbtion and osmosis of water)
The rest of the liquid leaves the end of the nephron into the ureter as urine
How is water controlled in the body and what kind of mechanism is it
It’s an example of negative feedback
Brain detects concentration of plasma in blood
If low as lots water, pituitary gland releases less ADH hormone so kidneys reabsorb less water so urine is more dilute
If high as not much water, pituitary gland releases more ADH so kidneys reabsorb more water so urine more concentrated
What is negative feedback
If a faster increases, something will change to decrease that factor
What is the menstrual cycle
A 4 week cylcle where an egg is released through ovulation, the uterus lining thickens for the egg, a while later, the lining breaks down along with the egg and is released from the body through menstruation.
Timeline of what happens in menstrual cycle
Week one, menstruation takes place, period
Week two, lining of uterus is built up again
Day 14, ovulation takes place, egg released
Days 14-16, fertilisation most likely
Week 3-4 uterus lining continues to build up
What are the 4 hormones that control menstrual cycle, explain them and where they’re from
Oestrogen: high levels stimulates release of more LH. Released from ovaires. Stimulated by maturing egg follicles
Progesterone: inhibits release of LH and FSH. Released from ovaries. Released after ovulation when follicle becomes a corpus luteum.
LH: surge of this triggers ovulation. Released from pituitary gland. Triggered by high levels of oestrogen
FSH: causes growth and maturation of egg follicles. Released in low levels of progesterone from the pituitary gland.
What happens to menstrual cycle after fertilisation and why
It stops as corpus luteum continues to release progesterone so LH and FSH aren’t released so no ovulation
What are the parts of a human egg cell (specific)
Haploid nucleus only one set of chromosomes, not pair
Cytoplasm with nutrients
Lipid droplets
Name parts of sperm (specific)
Head (acrosome) containing enzymes that digest egg wall to get into it
Haploid nucleus
Middle section with mitochondria to create and release energy by respiration
Tail for swimming
What happens in fertilisation
Hundreds of sperm compete to enter the egg first
Once one does, egg cell membrane quickly changes so no more sperm can enter
The two haploid cells fuse to make a diploid zygote cell
He zygote divides many times to create an embryo which embeds into the uterus lining to grow and develop
Name and briefly explain 4 fertility treatments
IVF, egg removed from women, fertilised by sperm in pétri dish, one or two of strongest embryos put into uterus to develop
Egg donation, hormones given to another woman so she release several eggs, then fertilised by IVF and embryo placed into infertile woman
Surrogate mother, pairs gamates fertilised though IVF, embryo placed into surrogate mother who develops it and gives birth to it
Hormones, make woman release more eggs to increase chance of fertilisation, however it increases chance of having several children
What is a phenotype
What an individual looks like as result of chromosomes, e.g. Male, female
What is genotype
The genetic material of an individual
What are alleles
Different forms of the same gene
Genotype and phenotype chart for haemophilia gene
XH XH female, normal clotting, no haemophilia, not carrier
XH Xh female, normal clotting, no haemophilia, carrier
Xh Xh fœtus doesn’t normally develop
XH Y male, normal clotting, not carrier
Xh Y mâle, haemophilia, carrier
