Homeostasis Flashcards
In the human body, homeostasis controls
Blood glucose concentration
Body temperatures
Water levels
Receptors
Cells that detect stimuli
Coordination centers
Process the information received from the receptors
Effectors
Bring about the responses to bring the conditions in the body back to optimun levels
Abstinence
Deliberately refraining from having sexual intercourse
Accommodation
The process of changing the shape of the lens to focus on near or distant objects
Adrenaline
A hormone that is produced by the adrenal glands in response to fear or stress which increases the heart rate and boosts the delivery of blood to the brain and muscles as a part of the “fight” or flight” response
Antidiuretic hormone (ADH)
A hormone that increases the re absorption of water water on the kidney tubules
Coordination centres
Areas of the body like the brain, spinal cord and the pancreas that receive and process information from receptors.
Deamination
A process occurring in the liver that removes the amino group from an amino acid to produce ammonia
Dialysis
A method of treating kidney failure or disease where the blood is artificially filtered to remove waste and toxins
Effectors
Muscles or glands which bring about responses which restore optimum levels.
Ethene
A type of plant hormone which controls cell division and the ripening of fruits
Follicle stimulating hormone (FSH)
A female reproductive hormone that causes the maturation of an egg in the ovary.
Geotropism/gravitropsm
A plants directional growth response to gravity
Gibberellins
A type of plant hormone which initiates seed germination
Gland
A group of cells that secrete chemicals called hormones directly into the bloodstream
Glucagon
A hormone produced by the pancreas that causes glycogen to be converted into glucose and released into the blood
Homeostasis
The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.
IVF
Fertilizing a woman’s egg using sperm outside the body
Hyperopia
A defect in the eye where nearby objects appear out of focus also called farsightedness
LH
A female reproductive hormone that stimulates the release of an egg
Myopia
A defect in the eye where distant objects appear out of focus
Oestrogen
The main female reproductive hormone which causes the uterus lining to grow and repair
Phototropism
A plants direction growth response to light
Reflex action
A rapid and automatic response to a stimulus
Selective reabsorbtion
Reabsorbing certain molecules back into the blood after they had been filtered out.
Stimuli
changes in the environment
Target organ
The organ which a hormone acts on to produce an effect
Testosterone
The main male reproductive hormone produced by the tests and it stimulates sperm production
The brain
An organ made of billions of interconnected neurones which controls complex behavior and different regions that carry out different functions
The CNS
The brain and spinal cord which coordinate the response of effectors
Thermoregulartory centre
An are of the hypothalamus in the brain which contrains blood temperature receptors and regulates body temorautes
Thyroxine
A hormone produced by the thyroid gland that increases the metabolic rate in the body
Type 1 diabetes
A disorder which the pancreas fails to produce sufficient insulin which is characterized by uncontrolled high blood glucose levels
Type 2 diabetes
A disorder where the body cells no longer respond to insulin produced by the pancreas
Vasoconstriction
The constriction of blood vessels
Vasodilation
The dilation of blood vessels
Peripheral nervous system
nerve cells that carry information to or from the CNS
What is a bundle of neurones called
a nerve
Features of a neurone
- Has a axon which is insulated by a myelin. They are also long so can carry messages up and down the body
- Tiny dendrons which can branch further as denrites at each end. These receive incoming impulses from other neurones.
Why is a reflex arc faster than normal responses
Follows the general sequence and does not involve the conscious part of the brain, which makes it much quicker
Order of stimulus to response
Stimulus –> receptor –> sensory neurone –> relay neurone –> motor neurone –> effector –> response
When two neurones meet there lies a gab what is the gab called
A synapse
How does information go from one side of the synapse to the other .
- An electrical impulse travels along the first axon
- This triggers the nerve - ending of a neurone to release neurotransmitters.
- These chemicals diffuse across the synapse and bind with the receptor molecules on the membrane of the second neurone.
- The receptor molecules on the second neurone bind only to specific neurotransmitters released from the first neurone. This stimulates the second neurone to transmit the electrical impulse.
Rule drop test practical (If you don’t know it go blurt it rn bitch)
- Work with a partner
- Person A holds out their hand with a gap between their thumb and first finger
- Person B holds the ruler with the zero at the top of person A’s thumb
4.Person B drops the ruler without telling person A and they must catch it
- The number level with the top of person A’s thumb is recorded in a suitable table. Repeat this 10 times.
- Swap places and record another 10 attempts.
- You can use the conversion table to help convert your ruler measurements into reaction time or just record the catch in distance cm.
- Then repeat the practical but first drink a can of coca cola that contains caffeine
cerebrum
Outer layer is called the cerebral cortex. Which splits into two hemispheres and is highly folded it controls intelligence, personality, conscious thought and high level functions such as language and verbal memory
The cerebellum
Which controls the balance coordination of movement and muscular activity
Medulla
Controls the unconscious activities such as heart rate and breathing rate
Hypothalamus
Which is the regulating center for temperature and water balance within the body
EEG’s are
Where scientists stimulate different parts of the brain with electrical current and see what the person does to this new current
MRI brain scans
Uses strong magnetic fields and radio waves to show details of the brain structure and function. Patients are asked to perform various tasks and by looking at the scan scientists can see which parts of the brain are active when the task is carried out.
Neurosurgery important things to consider
All surgery can be deadly but the brain is so complex and delicate that doing it could leave to more damage or side effects which may effect the patients life. The should decide if it is worth it.
Cornea
Refracts light
Iris
Controls how much light enters the pupil
Lens
Further refracts light to focus it onto the retina
Retina
Contains the light receptors
Optic nerve
Carries impulses between the eye and the brain
Sclera
Tough white outer layer of the eye. Helps protect eye from injury
Which are more sensitive to light rods or cones.
Rods
Rods
are used to see levels of light
Cones
Are used to see colour
Pupil reflex
The amount of light entering the eye is controlled by a reflex action. The size of the pupil changes in response to bright or dim light. This is controlled by the muscles of the iris
When light is dim are the radial muscles of iris contracted or relaxed
Are the circular muscles of the iris relaxed or contraccted
Radial muscles are contracted when dim
Circular muscles are relaxed.
When light is bright are radian muscles of iris relaxed or contracted
Are circular muscles of the iris contracted or relaxed
Relaxed
Contracted
When an eye views an object close to it how does it respond
Ciliary muscles contract
Suspensory ligaments slacken/loosen
Muscle tension is low
Lens shape is fat/thicker
Refraction light is strongly refracted
When an eye views an object distant from it how does it respond
Ciliary muscles relax
Suspensory ligaments stretch/tighten
Muscle tension is high
Lens shape is thin
Refraction is only refracted slightly
When someone suffers from myopia how could it be caused
The eyeball being elongated - so that the distance between the lends and the retina is too great
The lens being too think and curved - so that light is focused in front of the retina.
How can myopia be corrected
By placing a concave lens in front of the eye
How could hyperopia be caused
The eyeball is being too short so the distance between the lens and retina is too small
A loss of elasticity in the lens meaning it cannot become think enough to focus which is often age related.
Hyperopia can be fixed how
By placing a convex lens in front of the eye
Ways to fix eye problems
Laser surgery
Replacement lenses
Positive tropisms
The plant grows towards the stimulus
Negative tropisms
The plant grows away from the stimulus
Phototropism
Is a response to the stimulus of light
Auxins
Are a family of plant hormones.
Where are auxins mostly made
Mostly made in the tips of growing stems and roots, which are known as apical meristems, and can diffuse to other parts of the stems or roots.
What do auxins control
The growth of plants by promoting cell division and causing elongation in plant cells
Stems and roots response differently to auxin how do they respond differently
Cells in stems grow more
Cells in roots grow less
In a stem, the shaded side contains more auxin and grows longer, which causes the stem to ______ _____ ___ ______ and to note the plant does NOT bend towards the light
grow towards the light
Required practical (to investigate the effect of light or gravity on the growth of newly germinated seedlings)
blurt it rn if u don’t know it
ur probably feeling tired get the fuck up and work I dont give a fuck anymore.
- Put the cotton wool into three petri dishes, and then add equal volumes of water into each dish
- Add ten seeds to each dish and place them in a warm place where they won’t be distributed
- Allow the seeds to germinate and add more water if the cotton wool dries out.
- Once the seeds have germinated ensure the petri dishes each contain the same number of seeds, and remove any extra seeds if necessary.
- One petri dish will sit in full light on a windowsill, the second will be in a dark cupboard, and a final dish will be placed in partial light
- Every day for one week, measure the height of each seedling and record the results in a table. You must record the height of the individual seedlings on each day.
- Calculate the mean of the seedlings each day, and compare the mean heights in three different locations
Gibberelins
Are a group of plant hormones responsible for growth and development, are important for initiating seed germination.
Germination
Seed begins to sprout and grow
What can low concentrations of gibberelins be used for
To increase the speed of germination and they can stimulate cell elongation and cause plants to grow taller
Gibberellins mainly used for
End seed dormancy
Promote flowering
Increase fruit size
How can ethene be used in growing plants
It speeds up ripening in bananas and other fruit. It controls the cell division during plant growth.
In the food industry fruit is often picked unripe and then transported. This prevents fruit from over ripening on the journey. It is ripended during storage by adding ethene and then taken to the shops (READ)
In the food industry fruit is often picked unripe and then transported. This prevents fruit from over ripening on the journey. It is ripended during storage by adding ethene and then taken to the shops (READ)
Auxins can be used for
a weed killer
As rooting powder
For promoting growth in tissue culture
Disadvantage of weedkillers
Some species of animals rely on it as a food source. This can result in a reduction of biodiversity.
ADH
source =
organ
role
effects
Pitutary gland
Kidney
Controlling the water content of the blood
Increases reabsorption of water by collecting ducts
Adrenaline
source =
organs
role
effects
Adrenal glands
Several targets including the respiratory and circulatory system
Preparation for fight or flight
Increases breathing rate, heart rate flow of blood to muscles conversion of glycogen to glucose.
Insulin
source =
organs
role
effects
Pancreas
Liver
Controlling blood gluecose levels
Increase conversion of glucose into glycogen for storage
Negative feed back mechanism
Mechanism to lower raised levels of something and to raise reduced levels of something
Thyroxine
Stimulates the basal metabolic rate.
What happens if there are low thyroid levels in the blood stream
It stimulates the hypothalamus to release TRH and this causes the pituitary gland to release TSH so the thyroid gland releases more thryoxine so thyroxine levels return to normal
Normal thyroxine levels what happens
Normal thyroxine levels in the blood stream prevent TRH from being released from the hypothalamus and this prevents the release of TSH from the pituitary, so normal blood levels are maintained.
Adrenaline is released into the blood stream what effects does it create
Increases breathing rate, heart rate, and conversion of glycogen to glucose so more energy is released in the muscles.
It diverts blood away from areas, such as the digestive system towards the muscles
Action of insulin when there is low glucose
Effects on pancreas:
Effects on liver:
Effects on blood glucose levels:
Insulin not secreted into the blood
Does not convert glucose into gylocogen
Increases
Action of insulin when there is high glucose
Effects on pancreas:
Effects on liver:
Effects on blood glucose levels:
Insulin secreted into the blood
Converts glucose into glycogen
Decrease
If there is too much glucose in blood how does the pancreas respond
Produces insulin which enters the blood
Insulin allows glucose to be absorbed by body cells
Blood glucose reduced
Diabetes is a condition where
The blood glucose levels remain too high.
Diabetes treated how
By injecting insulin. The extra insulin causes the liver to convert glucose into glycogen which reduces the blood glucose level.
Type 1 diabetes
Is a disorder in which the pancreas fails to produce enough insulin. This can be detected from an early age. It is characterized by uncontrolled high blood glucose levels
Type 2 diabetes
In type 2 diabetes the person’s cells no longer respond to insulin produced by the pancreas. It is more common in older people. It can be controlled by a carbohydrate controlled diet an exercise regime. Carbohydrate is digested into glucose, which raises the overall bl65ood glucose level.
controlling high blood sugar levels (negative feedback) (4)
The hormone insulin plays a key role. When blood sugar levels rise in the blood, insulin sends a signal to the liver, muscles and other cells to store the excess glucose. Some is stored as body fat and other is stored as glycogen in the liver and muscles.
controlling low blood sugar levels (negative feedback) (4)
Whereas if the blood glucose level is too low the liver receives a message to release some of that stored glucose into the blood. This change is brought about by another hormone produced by the pancreas called glucagon.
Puberty boys
Voice breaks
Hair grows on face and body
Body becomes more muscular
Testes start to produce sperm cells
Puberty boys and girls
Pubic hair grows
Underarm hair grows
Sexual organs grow and develop
Why does the menstrual cycle occur
prepared for pregnancy
FSH (follicle stimulating hormone)
Produced where
Role
Produced : pituitary gland
Role: Cause an egg to mature in an ovary. Stimulates the ovaries to release oestrogen
Oestrogen
produced
role
Ovaries
Stops FSH being produced so only one egg matures per cycle. Repairs, thickens and maintains the uterus lining. Stimulates the pituitary gland.
LH
produced
Role
Triggers ovulation
Ovulation
Release of a mature egg
Progesterone
produced
role
Ovaries
Maintains the lining of the uterus during the middle part of the menstrual cycle during pregnancy
Menstruation cycle steps
Menstruation day 7
Lining of uterus builds up day 14
Lining maintained day 21
Lining breaks down menstruation day 28
Levels of Progesterone, LH and FSH stay for days 1-12
Eostrogen gradually increases and peaks on 12th day for the whole cycle.
Progesterone LH and FSH stay approximately at the same levels and begin to increase slightly from around day 12
FSH and LH hormones levels from 12-28
FSH and LH patterns are very similar and peak during ovulation
at approximately 14 days during this cycle. They drop sharply on day 15 and stay constant until day 28.
oestrogen and progesterone from day 13-21
Oestrogen drops during days 13 and 14, and progesterone continues to gradually increase until about day 21, when it slowly begins to decrease again. Oestreogen mirrors this shape and also has a second lower peak at about day 21
How the oral contraceptive work or the pill
Contraceptive injections, implants or skin patches contain slow release progesterone to inhibit the maturation and release of eggs.
Benefits of the pill/ oral contraceptive
they are more than 99% effective if taken correctly and can reduce the risk of certain cancers
Risks of oral contraceptives
There are possible side effects, such as changes in weight, mood and blood pressure due to high levels of oestrogen.
Physical barrier method
Condoms and diaphragms, which prevent the sperm reaching an egg.
intrauterine devices (IUD)
prevents the implantation of an embryo or release of a hormone
Spermicidal agents
Kill or disable sperm
Surgical methods of male and female sterilisation
A vasectomy is where the sperm ducts are cut and tied
Advantages and disadvantages of condoms
Easy and quick to use, but sometimes they can tear or rip
Diaphragms advantages and disadvantages
Need to be put in just before sex and left in several hour afterwards
IUD advantages and disadvantages
IUD can remain in position for up to 10 years.
However there is a small risk of causing an ectopic pregnancy
need to be fitted by a health professional
Spermicidal agents advantages and disadvantages
Are physical agents and kill the sperm
Though some people may have a allergic reaction
Abstaining advantages and disadvantages
Can be used successfully, but if the timings are not accurate the chance of pregnancy is high
Surgical methods advantages and disadvantages
Cannot be reversed and is permenant
you never have to use about contraception again
How would you help a women become pregnant if they don’t produce enough FSH to allow eggs to mature
Gives them drugs that contain FSH and LH, which stimulate eggs to mature in ovary
Fertility treatments advantages and disadvantages
Increase the chance of a woman becoming pregnant
Although the treatments may not work and increase the boost of production of mature eggs, this increases the chance of multiple pregnancies that carry a risk of premature or underweight babies
How may you help a women become pregnant if there are issues with the males sperm or a woman has blocked oviducts.
IVF can be used
IVF process 1 - 4 steps
(4)
IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs
The eggs are collected from the mother and fertilised by sperm from the father in a dish in the laboratory
The fertilised eggs develop into embryos.
At the stage when they are tiny balls of cells one or two embryos are inserted into the mother’s uterus (womb)
Advantages of IVF
It allows people to have babies of their own, who otherwise can’t due to a variety of reasons.
It has a safe track record and has been used since 1978. The embryos can be screened for genetic diseases, which is important for families that already have an affected child. Only unaffected embryos are used.
Unused eggs can be used for research or donated to other couples.
Disadvantages of IVF
here are side effects form the drugs used, such as hot flushes and severe headaches.
There is a possibility of multiple births, which is dangerous for mother and babies.
Ovarian hyper-stimulation syndrome (OHS), when too many eggs develop in the ovaries.
It is very emotionally and physically stressful.
The success rates are not high.
Ethical concerns of IVF
Some people believe couples only want designer babies with desirable qualities so may only want certain fertilised eggs.
Also, the embryos that are not used may be destroyed. Some people consider embryos to be new lives and view their destruction as unethical
Why does the human body want to maintain a temperature of 37 degrees
because this is the optimum temperature for enzymes
What controls the bodies temperature
The process is controlled by the thermoregulatory centre, which is contained in the hypothalamus in the brain
How is temperature felt
by receptors on the skin
What occurs when we get too hot
Sweat glands in the skin release more sweat. The sweat evaporates, transferring heat energy from the skin to the environment.
Blood vessels leading to the skin capillaries become wider - they dilate - allowing more blood to flow through the skin, and more heat to be lost to the environment. This is called vasodilation.
What occurs when we get too cold
Skeletal muscles contract rapidly and we shiver. These contractions need energy from respiration, and some of this is released as heat.
Blood vessels, which lead to the skin capillaries, become narrower - they constrict – which allows less blood to flow through the skin and conserve the core body temperature. This is called vasoconstriction.
Hairs stand on end to create an insulating layer, trapping warm air
Skeletal muscles contract rapidly (shivering) to generate heat from respiration
How do our hairs stand up
When we are too cold nerve impulses are sent to the hair erector muscles which contract raising the skin hairs.
Osmoregulation
is the control of water levels and mineral salts in the blood.
Why are water and mineral salts controlled in the blood
To protect cells by stopping too much water from entering or leaving them, as the concentrations of water and salts is the same inside and outside the cells. If body cells lose or gain too much water by osmosis, they do not function efficiently.
Hypotonic
More dilute solution outside the cell
cells will swell and may burst
Hypertonic
More concentrated solution outside the cell
Cells will shrivel
What happens to a plant cell when they undergo osmosis and are hypotonic
cells become turgid when they are full of water
What happens to a plant cell if they undergo osmosis and are hypertonic
Cytoplasm shrinks from cell wall.
e.gs of water loss from body
urine from kidneys
sweat from skin
water vapour, from lungs when we exhale
how does the skin lose water, ions and urea
they produce sweat which contain water ions and urea
How do the lungs release water
When you exhale as well as an excess of carbon dioxide
How does the body deal with an excess of amino acids
they need to be excreted safely. In the liver these amino acids are deaminated to form ammonia. Ammonia is toxic and so it is immediately converted to urea for safe excretion
Can the body store amino acids or proteins
no
