Homeostasis And Automatic Control System - 5 Flashcards
What is homeostasis? (HaACS Bi)
This is the regulation of the internal conditions of a cell or organism to maintain optimal conditions for function in response to internal or external changes in conditions. Homeostasis has the job of keeping the internal conditions of the body constant.
What are the three features of the automatic control system? (HaACS Bi)
- Receptor Cells
- Co-ordination Centre
- Effector
What are the two automatic control systems in humans? (HaACS Bi)
Nervous system and hormones
What is the purpose of receptor cells? (HaACS Bi)
Detects changes in the environment this is also known as detecting a stimulus
What is an example of internal change to the environment? (HaACS Bi)
Concentration of glucose in the blood.
What is an example of external change to the environment? (HaACS Bi)
Temperature of the skin.
What does the coordination centre do? (HaACS Bi)
Receives and Processes information from the receptor cells.
What are three coordination centres in the human body? (HaACS Bi)
- Brain
- Spinal Chord
- Pancreas
What is the purpose of effectors? (HaACS Bi)
To carry out a response / restore optimal levels
What are examples of effectors in the human body? (HaACS Bi)
Glands and Muscles
What is the order in which the automatic control system’s factors come? (HaACS Bi)
Receptor Cell -> Coordination centre -> effector
What are nerve cells called? (HaACS Bi)
Neurones
What are neurones adapted to do? (HaACS Bi)
They are adapted to carry electrical impulses from one place to another.
What is a bundle of neurones called? (HaACS Bi)
A nerve
What are the three types of neurone? (HaACS Bi)
Sensory
Motor
Relay
What do all types of neurones have in common? (HaACS Bi)
- A long fibre (axon)
- Tiny branches (dendrons)
What is the Axon? (HaACS)
A long fibre which is insulated by a fatty sheath. They are long so they can carry messages up and down the body.
What are dendrons? (HaACS)
Tiny branches which branch further as dendrites at each end. They recieve incoming impulses from other neurones.
What does an electrical impusle do? (HaACS)
They are pieces of information which pass through neurones from the receptor cells to the co-ordination centres.
What is an example of an electrical impulse?
The central nervous system. CNS
Where is the CNS located?
The brain and spinal chord.
What are some responses that come from effectors co-ordinated by the CNS (HaACS)
Muscles contracting or glands secreting hormones.
What is the flow of action from the stimulus to the response? (HaACS)
Stimulus -> Receptor -> co-ordinator -> effector -> response
How does information flow from receptor to effector in the nervous system? (HaACS)
Motor Neurones
|
Receptors - - - - - - - - > CNS - - - - - - - - - - > Effectors (Muscles and Glands)
| |
Sensory Neurones Relay neurones
What do sense organs contain and what do they do ? (HaACS)
Contain groups of Receptors that respond to specific stimuli.
What are the five types of sense organ?
- skin
- tongue
- nose
- eye
- ear
What is the skin’s stimuli? (HaACS)
- Touch
- Temperature
- Pain
What are the Tongue’s stimuli? (HaACS)
Chemicals (food and drink)
What are the Nose’s stimuli? (HaACS)
Chemicals (In the air)
What is the Eye’s stimuli? (HaACS)
Light
What is the Ear’s stimuli? (HaACS)
Sound and position of head
What are some examples of effectors in action? (HaACS)
- A muscle contracting to move an arm
- Muscle squeezing saliva from the salivary gland
- A gland releasing a hormone into the blood.
What is the method of measuring Reaction Time? (7RT H Bi)
- 1 sits on a stool with an upright posture and places their dominant arm on the table with their hand hanging over the edge of the table.
- 2 holds a metre long ruler vertically in their hands.
0 should be between the first finger and thumb - person 2 tells them to prepare to catch the ruler and they drop it at a random time.
- person 1 should catch the ruler with the thumb and forefinger as quickly as they can after the ruler drops
- 2 records the measurements on the ruler that is level with the top of 1’s thumb
- number one has a short rest
- the test is repeated several times and calculate the mean and then convert the results using a conversion table.
- 1 & 2 switch roles (which allows to see differece in reaction times.)
How do you convert the results into reaction times? (7RT H Bi)
by using a conversion table
you can find these online.
What is the independent variable for the test for reaction time? (7RT H Bi)
the person who is having their reaction time tested.
What is the Dependent variable for measuring reaction time? (7RT H Bi)
The reaction time
What is the Control Variables for measuring reaction time? (7RT H Bi)
- starting distance between the thumb and forefinger
- measure from the top of the thumb
- conditions in the room the same
lighting and background noise
What happens if we change any of the control varibales in the reaction time practical? (7RT H Bi)
the dependent varibale will change aka the reaction time
What other independent variables could we investigate in the practical for reaction time? (7RT H Bi)
- the effects of practice
- if reaction time depends on the hand catching the ruler
- if certain chemicals affect reaction time
What is the method of investigating the effect of practice on the reaction time? (7RT H Bi)
What is the expected result?
one person would catch the ruler a large amount of times and then they check to see if the reaction time changes depending on the number of tries
expected: reaction time will get shorter the more practice.
What is the method for seeing if the hand you use changes the reaction time? (7RT H Bi)
What is the expected result?
test with the persons dominant hand and then the non-dominant hand of the same person
expect: reaction time to be shorter for dominant hand because we use it more
What is the method for measuring the change in reaction time due to chemicals? (7RT H Bi)
What are the problems and how do we check?
The test subject drinks a measured amount of cola half an hour before the experiment. Compare this reaction time to the normal one.
problems: 1. other chemicals in the cola may affect reaction time
carry out the test using a caffine free cola and compare this reaction time with the normal one
2. check for medical things that caffine may affect : allergy / heart condition
3. carry out in a lab where hazordous chemicals aren’t usually used
Where are the adrenal glands located? (NF H Bi)
At the top of the kidneys
What hormone does the adrenal gland produce and under what circumstances? (NF H Bi)
during times of fear or stree, the adrenal glands produce the hormone adrenaline.
What is one of the main affects of adrenaline and what happens becuase of it? (NF H Bi)
increase the heart rate which means that more oxygen and glucose are delivered in the blood to the brain and the muscles. This prepares the body to either fight or run away. (flight or flight)
Where is the thyroid gland located? (NF H Bi)
the base of the neck
What hormone does the thyroid gland produce? (NF H Bi)
thyroxine
What are the two main effects of thyroxine? (NF H Bi)
- stimulates the body’s basal metabolic rate (makes the body’s chemical reactions take place at a faster rate.)
- plays an important role in growth and development
What is metabolism? (NF H Bi)
the sum of all the reactions in a cell or the body
What is the level of thyroxine in the blood controlled by? (NF H Bi)
Negative feedback
What is the idea behind negative feedback? (NF H Bi)
If the levels of a specific hormone drop, events are triggered to increase the levels of that hormone. If the levels of a hormone become too high, events are triggered to bring it back down.
Hormone levels are monitered by the brain. When they fall the pituiatry gland sends out a hormone (TSH) into the bloodstream. This triggers its target gland to produce more of the required hormone. Once the levels are back up the pituaitary gland stops producing this hormone because the increase has been detected by the brain.
What are examples of when the body uses negative feedback? (NF H Bi)
control of blood glucose and the menstrual cycle
What do oral contaceptives such as the pill do? (C H Bi)
they contain hormones which prevent the body from producing the hormone FSH which prevents any eggs maturing
What does the hormone FSH do? (C H Bi)
FSH causes an egg to mature
What are the advantages and disadvatanges of using oral contraceptive e.g the pill? (C H Bi)
Advantages:
it is highly effective if it is taken correctly
Disadvantages:
- must be taken every day becuase if they forget then there is a risk of pregnancy
- they also have a risk of side effects e.g breast cancer or blood clots (these are small though)
- doesnt protect against STIs e.g HIV
What are some side effects of taking oral contraceptive pills? (C H Bi)
Some of them mean that there is an increased risk of breast cancer or blood clots
but these risks are small
What are the types of contraception that invole hormones? (C H Bi)
the pill
implants
skin patch
injection
Which types of contraceptives contain progesterone and what does it do? (C H Bi)
injection
implant
skin patches
it stops eggs from maturing or being released
What are the advanatges and disadvantages of contraceptives containing progesterone? (C H Bi)
Advantage:
more conventiant than taking a daily pill
Disadvantage:
- can have side effects
- doesn’t protect against sexually transmitted infections STI e.g HIV
How long does the implant (contaception) last? (C H Bi)
3 years
How long does the contraceptive injection last? (C H Bi)
thirteen weeks around
How long does the contraceptive patch last? (C H Bi)
around one week
What are included in the barrier methods of contaception and what do they do? (C H Bi)
condom or diaphragm
they prevent the sperm from reaching the egg
What are the advantages and disadvantages of using barrier methods of contraception? (C H Bi)
Advantage:
- effective when used correctly
- don’t use hormones so no side effects
- condoms reduce the risk of STIs
Disadvantage:
- they can break or slip off
What could make barrier methods more effective and what do they do? (C H Bi)
spermicide gel
kill or disbale sperm and they reduce the chances of fertilisation
What do intrauterine devises or IUD (coil) do and how effective are they? (C H Bi)
They can prevent an embryo from implanting and some release hormones to reduce the chances of fertilisation
They are very effective and can prevent pregnancy for up to ten years and have few side affects but doesnt protect against sexually transmited infections
What does sergical forms of contraception / sterilisation do for men and women? (C H Bi)
women: prevents the egg from reaching the uterus
men: prevents the sperm from leaving the penis
Is sterilisation contraception effective and how evaluate it? (C H Bi)
Yes but very difficult to reverse and don’t protect against STIs
What is the method for natural contracteption? (C H Bi)
abstaining from sexual intercourse during the time after ovulation
What is the problem with natural contraception? (C H Bi)
very hard to tell when a woman has ovulated and doesn’t protect against STIs
Who has a problem with contracteption? (C H Bi)
- the catholic church thinks it is unethical apart from natural methods
- others believe that it is the persons choice whichever is best for them
What is a fertility drug? (HTI H Bi)
When a woman who is struggling with infidelity is given FSH and LH. This causes a woman to ovulate more than usual which increases chances of pregnancy.
What happens in in-vitro fertilisation (IVF)? (HTI H Bi)
fertilistation is taking place outside of the body.
The mother is first treated with FSH and LH which causes several eggs to mature which are then collected from the mother. At this point, sperm from the father is collected and it is used to fertilise the eggs in the laboratory. These eggs then grow into embryos. Once the embryos are tiny balls of cells, these are inserted into the mother’s uterus. These can now develop in the usual way inside the mother
What is the benefit of IVF? (HTI H Bi)
it gives a woman the chance to have a baby of her own
What are the problems with IVF? (HTI H Bi)
- the success rates are not high
- IVF can lead to multiple births which is risky for both the babies and the mother
- stressful for both parents and is also physically demanding on the mother: drugs and collection of eggs
- not all the embryos that are created will be transferred into the mother (many embryos are destroyed and some find this unethical)
- expensive and some people think that this money could be spent on other medical issues for example treatments for cancer
What is phototropism? (PH H Bi)
plants growing towards the light.
What is it called when plants grow towards the sun? (PH H Bi)
phototropism
What is the way that scientists found out that the hormone for plant growth is in the tips? (PH H Bi)
They put some shoots next to sunlight coming from one angle and they grew in the direction of the sunlight
They then removed the tips of these shoots and found that they did not grow towards the light anymore.
What is the name of the hormone making plants grow towards the light in the tips of shoots? (PH H Bi)
auxin
What tells us that the tips of plant shoots are sesitive to light? (PH H Bi)
scientists covered the tips of shoots with foil and they did not grow towards the light. They then covred the lower parts of the shoot and not the tips and they grew towards the light as normal. which tells us that the lower parts of the shoot are not sensitive to light.
How does auxin work in terms of photoropism? (PH H Bi)
- auxin is produced at the very tip of the shoot and this triggers cell growth in the shoots
- light causes auxin to concentrate on the darker side of the shoot tip
- it then spreads down the shoot so cells on the darker side grow faster than the cells on the lighter side. This causes the shoot to grow towards the light
What is the name asigned to when plants’ roots grow down? (PH H Bi)
gravitropism or geotropism
What is the process of auxin in terms of gravitropism? (PH H Bi)
- auxin is produced in the root
- gravity causes the auxin to concentrate on the lower side
- auxin inhibits cell growth in roots so the lower side now grows more slowly than the upper side
- the roots grow towards gravity
What is the importance of giberellins? (PH H Bi)
they start the germination of seeds
Which chemical starts the germination of seeds? (PH H Bi)
Giberellins
What does the chemical ethene do in plants? (PH H Bi)
controls the division and the ripening of fruits
Which chemical controls the cell division and the ripening of fruits in plants? (PH H Bi)
ethene
What is agriculture and horticulture? (UPH H Bi)
a = growing food crops
h = growing plants for gardens
What are auxin’s three main uses? (UPH H Bi)
- weedkillers
- rooting powders
- promoting growth in tissue culture
What can gibberellins be used for? (UPH H Bi)
- end seed dormancy (force a seed to germinate earlier than it normally would
- encouage plants to flower
- make fruit grow larger
What are some of the uses of ethene? (UPH H Bi)
- fruits such as bananas are harvested before they are ripe so that they can be transported long distances and can be stored before they are needed. Ethene is then used to trigger the bananas to ripen just before they are sold
What do enzymes and cells require to be able to work? (H H Bi)
stable conditions - enzymes and cells cannot work well if the conditions around them change too much
What is the definition of homeostasis? (H H Bi)
the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes
What does homeostasis consist of? (H H Bi)
automatic control systems which make sure that the internal conditions of the body stay as constant as possible
What are the general features of automatic control systems? (H H Bi)
- they can involve the nervous system or hormones
- receptor cells - coordination centre - effector
What do receptor cells detect? (H H Bi)
changes in the enviroment (internal and external conditions)
e.g concentration of blood glucose
e.g temperature of the skin
stimulus
What are examples of coordination centres? (H H Bi)
brain spinal chord or the pancreas
What are examples of effectors? (H H Bi)
muscle or gland
What is the job of an effector?
carry out a response / restore the optimum level
What is osmosis? (K H Bi)
The diffusion of water from a solution with a high concentration of water molecules to a soltuion with a lower concentration of water molecules through a partially permeable membrane
What happens if the blood becomes lacking in water? (K H Bi)
water moves into the cells through osmosis
What happens if blood cells gain or lose too much water by osmosis? (K H Bi)
they don’t work efficiently
How does the body take in water? (K H Bi)
through food and drink
What are the ways that the body can lose water and can the body control them? (K H Bi)
- via the lungs when we exhale - the body has no way to control this water loss
- sweat through skin - cannot control how much water is lost becuase it is part of the temperature control system
- via the kidneys in urine - can control
What are the important things in sweat? (K H Bi)
water
urea
ions (sodium)
How do the Kidney’s control how much water is lost through urine? (K H Bi)
if the blood is too dilute, the kidneys will remove the excess water and produce a greater volume of urine
How does blood enter the kidneys? (K H Bi)
through and artery which contains the waste product of urea
Where happens to the blood when it enters the kidneys? (K H Bi)
the kidney removes the urea and the excess ions and excess water from the blood from the artery which leave the kidney as urine and this is stored in the bladder. The blood (which contains no urea) then leaves the kidney through a vein.
How does the kidney adjust the level of molecules in the blood? (K H Bi)
- the blood passes through the capillaries
- small molecules are filtered out of the blood - urea, ions, water and sugar glucose
- these pass into a tube
- all of the glucose, some of the ions, some of the water and none of the urea is reabsorbed back into the blood - selective reabsorbtion
- Urea, excess ions and excess water are released as urine
How does the body deal with excess amino acids? (K H Bi)
When we digest protein, amino acids pass into the blood. When we get too much of them, the liver breaks them down and produces the chemical ammonia - deamination. Ammonia is a very toxic chemical so the kidney immediatly converts it to urea which is then safely excreted
What is deamination? (K H Bi)
When the liver converts amino acids that we don’t need into the chemical ammonia
What is the hormone that is released when the level of water in the blood falls? (MBWB H Bi)
ADH
What does the Hormone ADH do? (MBWB H Bi)
It travels to the kidneys when there is too little water in the blood. It causes the kidney tubules to become more permeable to water. (more water can now pass out of the kidney tubules) This means that more water is being reabsorbed from the tubules back into the blood. So less urine is produced and the amount of water in the blood rises back to its normal level. The pituitary gland stops releasing ADH.
What happens when the concentration of water in the blood becomes too much? (MBWB H Bi)
the pituitary gland stops releasing ADH which means that the kidneys reabsorb less water into the blood. Now more urine is produced and the concentration of water in the blood returns back to normal.
What do we do when a person’s kidney fails? (MBWB H Bi)
kidney dialysis - the levels of water, ions and urea need to be adjusted using a machine.
What is kindey dialysis? (MBWB H Bi)
When a persons kidneys fail and a machine controlles the levels of ions, water and urea in the blood
How does kidney dialysis work? (MBWB H Bi)
When someone was kideny failure, their blood will contain a higher concentration of water, ions and urea than it should.
1. The persons blood passes over a semi-permeable membrane which allows urea, ions and water through but not allow larger molecules such as proteins to pass through. Blood cells are all too large to pass through the mebrane.
2. On the other side of the membrane we have dialysis fluid which contains normal concentrations of water and ions but it does not contain any urea. We have a concentration gradient of urea so the urea diffuses from the blood into the dialysis fluid. The dyalysis fluid is constantly refreshed so that there is always a large concentration gradient for urea.
3. Since there is a normal concentration of water and ions, some of the water and some of the ions will diffuse from the blood into the dialysis fluid. So the concentrations of water and ions will return to normal in the patients blood.
Why can kidney dialysis be iconvenient? (MBWB H Bi)
- patients have to go to hospital several times a week
- eat a controlled diet so they do not produce too much urea
What is a better alternative to kidney dialysis if a kidney stops working? (MBWB H Bi)
a kidney transplant.
What happens in a kidney transplant? (MBWB H Bi)
diseased kidney is repleaced with a healthy kidney from a donor however in some cases the donated kidney may be rejected by the patient’s immune system.
What are the comparrisons between kidney dialysis and kidney transplants? (MBWB H Bi)
Dialysis:
1. no shortage of dialysis machines
2. patients require frequent treatments and a controlled diet making it inconvenient
3. expensive and long term
4.
Transplant:
1. sortage of kidney donors
2. allows the patient to lead a normal life
3. only expensive initially
4. patients have to take anti-rejection drugs for the rest of their lifes
What do all automatic control systems have in them? (NS H Bi)
Stimulus, Receptor, Coordination centre, effector, response
What are the two parts of the nervous system? (NS H Bi)
- Central nervous system (brain and spinal chord)
- other nerves running to and from the central nervous system
What happens after a recptor cell senses a stimulus? (NS H Bi)
They detect the stimulus and send electrical impulses down neurones to the central nervous system (cooradination centre). This now sends electrical impulses down other neurones to effectors which then bring about a response.
What is the key role of the nervous system? (NS H Bi)
enables humans to react to their surroundings and coordinate their behaviour.
Describe the reflex arc (hot object): (NS H Bi)
- stimulus is detected by a receptor (stimulus = heat, receptor = skin)
- electrical impulses now pass from the receptor along a sensory neurone to the central nervous system.
- at the end of the sensory neurone is a junction called a synapse
- At the synapse a chemical is release which now diffuses to a relay neurone in the central nervous system where it triggers and electrical impulse.
- the electrical impulse now passes across the relay neurone and reaches another synapse, another chemical is released which triggers an electrical impulse to a motor neurone
- the electrical impulse passes down the motor neurone to an effector (muscle which contracts)
What is the junction at the end of a sensory neurone called? (NS H Bi)
A synapse
Is there any decision making by the consious part of the brain during a reflex arc? (NS H Bi)
No, which makes reflexes automatic and rapid. This helps to protect us from danger
What does the brain control and how does it do this? (B H Bi)
complex behaviour e.g language
to do this, the brain contains billions of interconnected neurones
What is the highly folded, outer part of the brain called and what are its functions? (B H Bi)
the cerebral cortex’s functions include language, memory, and consciousness.
What is the second biggest part of the brain called and what are its functions? (B H Bi)
the cerebellum controls balance and co-ordinates our movements
What is the smallest part of the brain called and what are its functions? (B H Bi)
Medulla and it controls our heart rate and our breathing rate
Why is the brain difficult to study and treat brain damage or diseases? (B H Bi)
- the brain is protected by the skull so it is very tricky to access
- the structures of the brain are extremely complex so its difficult to work out exactly which parys of the brain carry out specific functions
- the brain is extremely delicate and easy to damage
What are the three ways that scientists use to investigate the brain? (B H Bi)
- study patients who have brain damage. ~ by looking at where the damage was taken, they can try to link that part of the brain to its function
- electrically stimulate different parts of the brain and look at the effects on the person’s behaviour ~ this allows us to narrow down specific regions to their functions
- MRI scanning to look at which parts of the brain are most active during different activities
