Homeostatis and Response (Paper 2) Flashcards
What is meant by homeostasis
Regulation of internal environment within cell/ organism to maintain optimum conditions for function (life)
What 3 main conditions must be controlled in homeostatis
Body temperature
Water levels
Blood glucose concentration
What 2 systems are used to control homeostasis
Nervous system
Endocrine system
3 main parts of control system
Receptor (detect change)
Coordination centre (interprets change and decides what needs to be done)
Effector (carry out change)
Part of control system that detects change
Receptor
Part of control system that interprets change/ decides what to do about the change
Coordination centre
Part of control system that carries out the change
Effector
2 types of effectors
Muscles/ glands
Negative feedback control system meaning and example of how it works
Where the automatic control system counteracts the change identified by receptors
E.g if temperature increases, it decreases the internal body temperature to keep it stable
E.g if you walk into a cold room, the receptors in our skin detect the low temperature, nervous system sends impulses to coordination centres which interpret the information, then signals are sent to the effectors e.g muscles which can shiver to overtime increase body temperature (skeletal muscles move and generate heat)
What is meant by Thermoregulation
Control of internal body temperature
Name for control of internal body temperature
Thermoregulation
Where are most receptors found in the body
Sense organs
E.g eye, skin, ear, nose wire etc
Name for process where muscles contract automatically to keep us warm
Shivering
What type of cell in the nervous system detects a change in the environment
Receptor
When body temperature is too… the blood vessels dilate
High
When body temperature is too…the blood vessels constrict
Low
What do blood vessels do when the body temperature is too high
Dilate
What do blood vessels do when body temperature is too low
Constrict
Dilate meaning
Become wider/ more open
Constrict meaning
Narrow/ restrict
Vasodilation meaning
When blood vessels dilate (open wider)
What causes vasodilation to occur
When body temperature is too high
What causes vasoconstriction to occur
When body temperature is too low
What centre in the brain controls and moniters body temperature
Thermoregulatory centre
Where in the body is the thermoregulatory centre located
Brain
What are the receptors found in the thermoregulatory centre sensitive to
Blood temperature
Main reason why our body temperature must be regulated to 37 degrees Celsius
Optimum temperature for enzymes to function
(below this temperature= lower rate of reaction)
(Above this temperature enzymes denature= lower rate of reaction then no reaction at all)
Which part of the brain is the thermoregulatory centre found in
Hypothalamus
Why does constricting blood vessels (vasoconstriction) help increase body temperature
Blood vessels that that lie near surface of skin are constricted (narrowed)
Less blood flows near surface
Less heat energy lost to surroundings
4 things body does in response to a decrease in body temperature
-Blood vessels constrict (less heat energy lost to surroundings)
-Shivering (skeletal muscles automatically contract so more respiration is required which releases more energy as heat)
-Hairs on skin stand up (due to hair erector muscles contracting- more air is trapped so provides insulation and less heat is lost from skin)
-Sweat less
Do the erector muscles contract when there is an increase or decrease in body temperature
Decrease
(Makes hairs on skin stand up to insulate body as traps layer of air preventing heat loss to warm body back up and regulate body temperature)
What happens to the hairs on the skin when the erector muscles contract and relax
Contract- hairs stand up so traps heat (insulation)
Relax- hairs lie flat to prevent insulation and cool body down
How does blood vessel dilation help cool down body in response to increase in body temperature
More heat energy can be transferred to surroundings as lots of warm blood is passing close to skin surface
What 2 things does sweat consist of
Water and salt
How does sweat help cool us down
It is a mixture of water and salts released onto the surface of the skin
As it evaporates, it takes heat energy from our body away with it (as lots of energy is required to evaporate water)
Why does blood vessels dilating help decrease body temperature
More warm blood can pass through so more heat is lost through skin to surroundings
Function of nervous system
Enables humans to react to their surroundings and to coordinate their behaviour (includes both voluntary and involuntary actions)
True or false, the nervous system includes both voluntary and involuntary actions
True
2 parts of the central nervous system
Brain and spinal cord
What type of actions don’t involve the conscious part of the brain
Reflex actions
What is a synapse
Gap between 2 neurones
(Allows impulses to cross)
Another word for short sightedness
Myopia
Another word for long sightedness
Hyperopia
Which out of myopia and hyperopia means short sightedness
Myopia
(Think myopia is the shorter word)
3 types of neuron
Sensory
Relay
Motor
The brain is the… centre of the body
Control
What part of the body is the control centre of the body
Brain
Name for bony case surrounding the brain
Skull
What is the skull
Bony case that surrounds the brain
Below the brain are membranes called….
Meninges
What are meninges
Membranes below the skull that protect the brain
Name for outer crinkly layer of brain important for consciousness, intelligence, language and memory
Cerebral cortex
What 4 things is the cerebral cortex important for
Memory
Language
Intelligence
Consciousness
What is at the back of the brain and important for muscular activity and balance
Cerebellum
Role of cerebellum at back of brain
Muscular activity and balance
What part of the brain is the regulatory centre (including containing the Thermoregulatory centre)
Hypothalamus
What is at the base of the brain and important for involuntary actions like heart rate, gut movements and breathing
Medulla
Where about in the brain is the medulla
Base of brain
Role of medulla at base of brain
Involuntary activities (heart rate, gut movements, breathing…)
Part of brain responsible for involuntary actions like breathing
Medulla
(Found at base of brain)
What gland in the brain controls hormones
Pituitary gland
Role of pituitary gland in brain
Controls hormones
Definition of receptor
Groups of specialised cells that enable us to detect changes in the environment
Neuron definition
Specialised cells that conduct electrical impulses through the body
Nerve definition
Bundle of many nerve fibres (neurons) enclosed within a protective sheath
What does a sensory neuron connect
Receptor to coordination centre
The sensory neuron connects the… to the…
Receptor, Coordination centre
Type of neuron that connects receptor to coordination centre
Sensory
What does a motor neuron connect
Coordination centre to effector
The motor neuron connects the… to the…
Coordination centre, Effector
What does the relay neuron do
Create shortcut between sensory and motor neurons for our reflexes
Which type of neuron creates a shortcut between the sensory and motor neurons
Relay
Events in a reflex action
Receptor detects stimulus
Sensory neuron sends electrical impulses to relay neuron
Relay neuron connects sensory neuron to motor neuron
Motor neuron sends electrical impulses to effector
(Motor neurone takes away need to go past brain (coordination centre) I think
What is a reflex action
Rapid and automatic response of the nervous system that doesn’t involve conscious thought
(Doesn’t require brain)
Name for nerve pathway followed by a reflex action
Reflex arc
What is a reflex arc
Nerve pathway taken in a reflex action
Main purpose of reflex actions
Prevent injury (keep you out of danger)
What does CNS stand for
Central nervous system
What does the central nervous system (CNS) consist of
Brain and spinal cord
True or false, neuron and neurone are the same thing
True!
How do the brain and spinal cord receive information about what’s happening in the rest of the body
Sensory neurones
(Sensory neurones go from receptor to brain/ spinal cord)
How does the CNS send impulses back out to the body (once it’s decided what to do with the information given to it by the sensory neurones)
Vía motor neurones
Name for cells found in nerves that carry information
Neurones
What coordinates the response to a stimulus
The brain
Three types of neurones that are part of the central nervous system
Relay
Motor
Sensory
True or false, each of the brain’s regions performs a different function
True
When light hits the eye what’s the first structure that it meets
Cornea
Why is the cornea transparent
Allows all light that hits it to completely pass through (the cornea is the first part of the eye that light hits)
True or false, the cornea has blood vessels
False
It has no blood vessels so that it is transparent and light can completely pass through (it’s the first part of the eye that light hits)
Why is the cornea transparent with no blood vessels
So that light can completely pass through (it’s the first part of the eye that light hits)
What does the cornea do to all the light that passes through it
Causes it to refract
The cornea causes all the light that passes through it to…
Refract
Part of eye that causes all light that passes through it to refract
Cornea
Role of cornea
Allows all light that passes through it to refract
Refraction meaning
When something changes direction when it meets a new medium (material)
(E.g light changes direction when it passes through the cornea of the eye)
Name for coloured part of eye
Iris
The iris controls how… the pupil is
Big or small
What part of the eye controls how big or small the pupil is
Iris
True or false, the pupil isn’t an actual structure of the eye
True
It’s a gap in the middle of the iris that allows light to pass through to the lens
Name for gap in middle of iris that allows light to pass through to lens
Pupil
True or false, both the role of the lens and cornea refract light
True
2 parts of eye that refract light
Cornea and lens
Both the cornea and lens refract light but which can change shape (gets thicker/ thinner)
Lens
Purpose of lens being able to change shape
Allows it to control how strongly it refracts the light to help focus near/ distant objects
What about the lens makes it able to control how strongly it refracts the light
It can change shape
The lens allows light to always focus on the…
Retina
Why is it good if the lens can change how strongly it refracts light (by changing shape)
Allows light to always focus on retina in order to focus both distant and nearby objects
How many different types of receptor cells is the retina made up of
2
Type of receptor cell sensitive to colour of light
Cone cell
2 types of receptor cells found in retina
Cone and rod cells
Role of rod cells
Only allow us to see in black and white
Which type of light do cone cells not work well in
Dim light (when it’s dark which is why we also have rod cells)
Type of receptor cell in retina that allows us to see in colour
Cone cell
Type of receptor cell in retina that allows us to see in black and white
Rod cell
Region of retina that only contains cone cells not rod cells
Fovea
(Where the lens mostly tries to focus light on so that we can see more clearly)
The fovea only contains…cells not…cells
Cone, rod
The optic nerve transmits…from receptor cells to brain
Impulses
Part of eye that transmits impulses from receptor cells to brain
Optic nerve
Role of optic nerve
Transmits impulses from receptor cells to brain
Name of muscles on inside of iris that control size of pupil (to allow more/ less light to get through to retina)
Circular muscles
Name of muscles on outside of iris
Radial muscles
2 types of muscles that iris contains
Circular (inside)
Radial (outside)
In bright light does the iris want to make the pupil smaller or wider
Smaller
(So that less light can get through to the retina)
In dim light does the iris want to make the pupil smaller or wider
Wider
(So that more light can pass through to the retina)
In what type of light do the circular muscles contract and radial muscles relax
Bright
Where in the eye are the circular and radial muscles found
Iris
What does the iris do in bright light to make the pupil constrict (narrow) so less light can pass through
Circular muscles (inside of iris) contract (which squeezes the pupil smaller)
Forces radial muscles (outside of iris) to relax
What does the iris do in dim light (darkness) to allow the pupil to widen so that more light can pass through
Circular muscles (inside of iris) relax (allows pupil to widen)
Radial muscles forced to contract (are made shorter and force pupil open)
Name for process that allows us to see both near and distant objects
Accommodation
What 2 things control shape of the lens
Ciliary muscles
Suspensory ligaments
Part of Retina that light needs to focus on
Fovea
(Part containing only cone cells to allow us to see in colour)
Does light need to be refracted more strongly when focusing on nearbye or distant objects
Nearbye (as light comes in at more of an angle)
To focus on a distant object do you need a thinner or fatter lens
Thinner lens
(As less refraction needed)
To focus on a nearbye object do you need a thinner or fatter lens
Fatter
(As more refraction is needed)
Role of ciliary muscles and sensory ligaments to focus on a distant object
Ciliary muscles relax
Suspensory ligaments pulled tight
Causes lens to become flatter and thinner
Role of ciliary muscles and Suspensory ligaments to focus on nearbye object
Ciliary muscles contract
Suspensory ligaments slack
Lens more rounded and thicker/ fatter
Part of eye where image is formed
Retina
Unconditional reflex meaning
A reflex we are born with- doesn’t have to be learnt/ involve the brain
Name for fluid in the front of the eye
Aqueous humour (provides nutrients to cornea and lens)
Hormones are all produced by what
Glands
What 2 hormones do the ovaries produce
Oestrogen
Progesterone
Progesterone and oestrogen are produced by which gland
Ovaries
What gland produces insulin
Pancreas
What hormone does the pancreas produce
Insulin
What hormone do the testes produce
Testosterone
What gland produces testosterone
Testes
What gland produces adrenaline
Adrenal gland
What hormone does the adrenal gland produce
Adrenaline
What is the endocrine system
Collection of glands which secrete hormones directly into the blood to be carried to a target organ where it has an effect
The endocrine system is a collection of what
Glands
What do the glands in the endocrine system secrete
Hormones
In the endocrine system where are hormones directly secreted into
The blood
Another word for chemical messengers
Hormones
What are hormones
Chemical messengers
Which gland is the master gland
Pituitary gland
Which organ is the pituitary organ located in
Brain
Where is the thyroid gland located
Neck
Where is the adrenal gland located
Top of kidneys
Name for sugar found in blood
Glucose
Name for storage carbohydrate that stores glucose and is found in the liver and muscles
Glycogen
True or false, glucagon is a hormone
True
Does the pancreas release insulin if there is an increase or decrease in blood glucose
Increase
What happens when our blood glucose levels increase
Páncreas detects increase
Pancreas releases insulin
Glucose taken in by muscle and liver cells
Glucose converted to glycogen
Blood glucose levels return to normal
What happens when our blood glucose levels decrease
Decrease detected by pancreas
Pancreas releases glucagon (hormone)
Stored glycogen converted back to glucose
Blood glucose levels return back to normal
When does the pancreas release insulin vs glucagon
Insulin when increased blood glucose levels
Glucagon when decreased blood glucose levels
2 things pancreas releases in response to increase/ decrease in blood glucose levels
Insulin (increase)
Glucagon (decrease)
Which gland secretes ADH (anti- diuretic hormone)
Pituitary gland
What might someone be suffering from if sugar is present in their urine
Uncontrolled diabetes
Name for tough outer structure that protects the eye
Sclera
The ciliary muscles and suspensory ligaments are to do with the lens, the circular and radial muscles are to do with the what
Iris
In which type of diabetes does the pancreas stop releasing insulin/ only does so in very small amounts
Type 1
Which age group is type 1 diabetes more common in
Children/ younger people
What does someone with type 1 diabetes have to inject into the self too stop their blood glucose levels becoming too high
Insulin
(As the pancreas doesn’t produce it/ produces an insufficient amount)
Why do people with type 1 diabetes need to be careful with their diet
The more sugary foods they eat, the higher their blood glucose levels are
Their body doesn’t release insulin to bring down the blood glucose levels, instead they have to inject it
Why is it important for someone with type 1 diabetes to do regular exercise
When we exercise our muscles absorb more glucose from the blood, automatically lowering our blood glucose levels (so they would need to inject less insulin to lower the blood glucose levels)
Type of people type 2 diabetes is most common in
Older people
Have eaten unhealthy diet for long time
What causes blood glucose levels to remain high in someone with type 2 diabetes
Person’s cells become resistant to insulin even though it’s still produced
So when insulin is released, less glucose is taken in by the cells
Why are insulin injections only effective for someone with type 1 diabetes not type 2
In type 1, the pancreas doesn’t produce insulin so by injecting it it allows glucose to be converted to glycogen like normal to lower blood glucose levels
In type 2, the cells have become resistant to insulin so injecting more of it will do nothing as the body won’t respond as it should
2 key ways to treat type 2 diabetes
Eat diet lower in carbs so that there is less blood glucose
Increase exercise (which causes more glucose to be stored by muscles, reducing blood glucose levels)
Urea is made in the liver during which process
Deamination
Type 1 diabetes symptoms
Tiredness (fatigue)
Thirst
Urinate lots
Weight loss
Blurred vision
Slow healing of wounds
Thyroxine is produced by the thyroxine gland using what from the diet
Iodine
Role of TSH
Controls basal metabolic rate in body
What hormone stimulates the production of thyroxine as part of the negative feedback loop
TSH (thyroxine stimulating hormone)
True or false, as TSH increases, thyroxine decreases and vice versa
True
This is to maintain optimum thyroxine levels to maintain basal metabolic rate
What changes to your body does adrenaline cause
Increased heart and breathing rate
Glycogen converted to glucose for respiration
Pupils dilate to let in more light
Blood diverted from digestive system to muscles
Main difference between 2 systems used to control homeostatis
Messages transmitted via electrical impulses (nervous system) vs hormones (endocrine system)
2 main poisonous waste products
Carbon dioxide
Urea
2 ways urea is produced
Eating excess protein
Worn out tissues
What is deamination
Where the liver removes the amino group from the amino acids
Deamination is where the liver removes what
The amino group from the amino acid
Why does Deamination occur
When you eat excess protein so urea is produced (initially ammonia is produced but ammonia is then converted to urea)- your body can’t store excess protein so it needs to be broken down (which happens in deamination where the liver removes the amino group from amino acids)
What process forms ammonia
Deamination (liver removing amino group from amino acid)
What is formed from deamination that’s toxic
Ammonia
True or false, ammonia is toxic
True
What is ammonia converted into that’s excreted from the body in urine
Urea
Which out of ammonia and urea can your body excrete safely
Urea
When ammonia is formed from Deamination (removing amino group from amino acid as excess protein can’t be stored so has to be broken down) it’s immediately converted into urea
If water concentration is too low will more or less ADH be released and what will be the consequence of this
Water concentration too low= more ADH released= kidney tubules re absorb more water= little urine produces= water concentrations in blood returns to normal
If water concentration is too high will more or less ADH be produced and what will be the consequence of this
Water concentration too high= less ADH released = kidney tubules reabsorb less water= more urine produced= water concentration in blood returns to normal
What produces urine
The kidneys
What 3 things does urine contain
Urea
Excess water
Excess Mineral ions
Where is urea made
Liver
(From deamination which produces ammonia but ammonia is immediately converted to urea)
What makes urine yellow
Urobilins
What from the breakdown of Haemoglobin makes urine yellow
Urobilins
What is Urobilins
What makes urine yellow
(Formed from breakdown of Haemoglobin)
Is more ADH released if water concentrations are too high or too low
Too low
(As more ADH means more water reabsorbed)
If more ADH is released is more or less urine produced by the kidneys
Less urine produced
(As more ADH is produced when water concentrations are too low- to increase the water concentration means keeping more water in the body and therefore losing less so less urine)
If less ADH is produced does that mean more or less urine is produced by the kidneys
More urine
(Less ADH is as a result of too high water concentration meaning more water needs to be removed from body so more urine is produced)
Which organ filters our blood
Kidneys
Apart from being lost through urine, what are 2 other ways water is lots from our body
Sweat
Lungs when we breathe out (water vapour)
Name for structures inside kidneys (there are around a million of them) that reabsorb more/ less water to help regulate water concentration in blood
Tubules
As blood passes through the kidneys, the tubules absorb small molecules like…(process is called filtration)
Glucose, water, urea, amino acids
(Not proteins as they’re too big)
What is meant by selective reabsorbtion
When blood passes through kidneys, the tubules absorb all small molecules like water, urea, glucose and amino acids (not protein as too big) then anything we want to keep is absorbed back into the blood including all glucose, some water and no urea
Name for process where when blood passes through kidneys, all small molecules like water, glucose, urea and amino acids are absorbed into the tubules
Filtration
Name for process where after blood passes through kidneys and all small molecules have been absorbed into tubules (urea, amino acids, water and glucose), some of these things are then reabsorbed back into the blood e.g all glucose but only some water
Selective re absorption
2 ways ions can be removed from the body
Sweating
Kidneys
Does ADH increase or decrease the concentration of water in our blood
Increase
Which artery brings blood containing urea, mineral ions, water and other substances in solution to the kidneys
Renal artery
Blood passes into the kidneys through the… and out through the…
Renal artery, renal vein
Does the renal artery or renal vein bring blood into the kidneys
Artery
Renal vein takes blood away from the kidneys
Where does urine travel down from the kidneys to the bladder
Ureters
Structure that carries urine from the bladder out of the body
Uretha
Which comes first, urethra or ureters
Ureters (carry urine from kidneys to bladder)
Urethra then carries urine from bladder out of the body
Term for when someone’s kidneys stop working
Kidney failure
Term for when someone’s kidneys stop working
Kidney failure
2 treatments for kidney failure
Dialysis
Kidney transplant
In dialysis, the patient’s blood passes through a what
Dialysis fluid
The dialysis fluid must have what type of membrane
Semi- permeable
Why must the dialysis fluid have a semi permeable membrane
Allow small molecules like ions to diffuse out of patients blood
True or false, dialysis fluid contains urea
False
Why must dialysis fluid be constantly replaced
So that there’s always a concentration gradient so that unwanted substances can keep diffusing out of the patient’s blood and into the dialysis fluid
Rejection meaning in transplant
The donated organ is attacked by the patient’s own immune system as it’s seen as being ‘foreign’
Why doesn’t ‘fresh’ dialysis fluid contain urea
It contains the ideal concentration of each substance in the blood (and ideally there’s no urea in filtered blood)
True or false, dialysis fluid contains the same concentration of useful substances as healthy blood
True
E.g it doesn’t contain urea
True or false, dialysis fluid contains the same concentration of useful substances as healthy blood
True
E.g it doesn’t contain urea
For a dialysis how many times a week must the patient go to hospital
3 times a week
Which out of a kidney transplant and dialysis has a risk of infection
Both
Which is more expensive in the long term kidney transplant or dialysis
Dialysis
True or false, for dialysis you have to go to hospital 3 times a week for the rest of your life
True
4 key disadvantages of dialysis
Must go to hospital 3 times a week for the rest of your life (time consuming)
Very expensive in long term
Risk of infection
No working kidney
5 key disadvantages of kidney transplant
Can be rejected by body
Risk of infection
Must take immunosuppressant drugs- can cause weaker immune system so more susceptible to other diseases
Not always donor available
Limited transplant lifespan of around 10 years
Why can kidney donors be both dead or alive
We only need 1 working kidney each
2 biological reasons most doctors think kidney transplant is a better treatment method to dialysis
Skin not repeatedly punctured
Lower risk of infection
What is puberty
A period in which adolescents start to develop secondary sex characteristics e.g facial hair and breasts and is triggered by reproductive hormones
What hormones trigger puberty
Reproductive hormones (mainly oestrogen is girls and testosterone in boys)
4 key hormones involved in menstrual cycle
FSH
LH
Oestrogen
Progesterone
Average length of menstrual cycle
28 days
Facts about stage 1 of menstrual cycle
Usually lasts 4 days
Period of menstruation (bleeding) due to break down of uterus lining (so thickness of uterus lining decreases)
Facts about stage 2 of menstrual cycle
Uterus lining starts to build up again
Lasts around 10 days up to day 14
Is preparing uterus lining for fertilised egg (by making it thicker) (as fertilised egg implants into uterus lining)
Facts about stage 3 of menstrual cycle
Day 14
Ovulation
Occurs in one single day
Egg is released from one of the ovaries
3 roles of oestrogen
Causes lining of uterus wall to thicken
Stimulates release of LH
Inhibits (stops) release of FSH
2 key roles of progesterone in menstrual cycle
Maintains thick uterus lining
Inhibits (stops) release of FSH and LH
Role of LH in menstrual cycle
Stimulates release of mature eggs from ovaries on day 14 (ovulation)
2 roles of FSH in menstrual cycle
Causes egg to mature in ovaries
Stimulates ovaries to produce oestrogen
Facts about stage 4 of menstrual cycle
Day 14-28
Involves maintaining lining of uterus
How level of oestrogen changes throughout menstrual cycle
Increases in stage 2 as is responsible for causing lining of uterus wall to thicken
Decreases in stage 3 once the lining has thickened as it no longer needs to thicken any more
How level of progesterone changes throughout menstrual cycle
Increases in stage 4 as responsible for maintaining the lining of the uterus
(When progesterone levels drop the uterus lining starts to break down so the cycle restarts)
Phototropism vs geotropism in plants
Phototropism = response to light
Geotropism = response to gravity
Do auxins accumulate on the shaded side or sunny side of the plant (in phototropism)
Shaded
Meaning of plant shoots being positively phototropic
They grow towards the light
Meaning of plant roots being negatively phototropic
They grow away from light
Main plant hormone
Auxin
Roots being positively geotropic meaning
Grow downwards towards gravity
Shoots being negatively geotropic meaning
Grow upwards (against gravity)
Difference between how stem and roots respond to auxins
Shoots- auxin means more growth
Roots- auxin means less growth
3 uses of Gibberellins
End seed dormancy
Promote flowering
Increase fruit size
Use of ethene in plants
Control ripening of fruit during transport and storage
3 uses of auxins in plants (apart from phototropism and geotropism)
Weed killer
Rooting powder
Promote growth in tissue cultures
Part of plant auxins are produced in
Tips of stems and roots
Do auxins accumulate on the upper side or lower side of the plant (when it’s horizontal e.g for geotropism)
Lower side
How do auxins travel through plant
Diffusion
(From tips of roots/ shoots where they’re produced)
