HOMEOSTASIS CGP Flashcards
-what is homeostasis
-what does homeostasis controlx3
-homeostasis maintans optimum conditions for cell functions and…….
regulation of internal conditions of cell/organism to maintain optimum conditions for function - in response to internal/ external changes.
-blood glucose concentration
-body temp
-water levels
enzyme action
all automatic control systems contains 3 things- what do each do
what 2 types of Responses can automatic control systems involve
- receptors, detect stimuli (changes in
environment) - coordination centres (brain, spinal cord, pancreas) receive + process info from receptors
- effectors, muscles / glands, produce responses to restore optimum levels.
-nervous, chemical
describe reflex arc from stimulus to effector - 6 steps
reflex arc similar to what happens when CNS coordinates a response but in reflex arc, its automatic/rapid so X involve consious part of brain, there’s an extra neurone instead.
-receptors detect stimulus
-electrical impulses pass along sensory to relay to motor neurones
-at synapse btwn neurones, chemicals cross the gap by diffusion and continue the electrical signal.
-the relay neurone is in spinal chord(CNS) so there are synapses there to carry the impulse to motor
-impulse travels from motor neurone to effector
-mucsle contracts/ gland secrete hormones
If level of something becomes too high/low body uses negative feedback- describe this for a high level
- the effector will keep producing response if stimulated by co-ord centre. What happens then
-receptor detects stimulus- level too high
-coordination centre processes info and organises response
-effector produces response which counteracts change . level decreases
-levels change too much the other way . receptors detect this, negative feedback happen again
4 parts of the nervous system- describe what they are/ do
-sensory neurones- carry electrical impulses from receptor cells to CNS
-cns- brain+spinal chord
-motor neurones-carry electrical impulses from CNS to effectors
-effectors-muscles/ glands -respond to impulses
what responses do glands/ muscles have
7 parts of how the CNS coordinates a response- from stimulus to response
- secreting hormones. contracting
1-stimulus, 2-receptor, 3-sensory neurone, 4-cns, 5-motor neurone, 6-effector, 7-response
what is synapse
what happens at a synapse
-connection btwn 2 neurones
-when electrical impulse reaches end of neurone, stimulates release of chemical.
-chemicals diffuse across synapse to activate electrical impulse in next neurone
why are reflex actions important- what are they
-automatic, rapid responses - don’t involve consious part of the brain- reduce chance of injury
RP reaction time- 5 steps
-sit with arm resting on edge of table
zero end should be level with persons thumb and forefinger
-let go- no warning
-measure reaction time by number on ruler when caught
-repeat few times, calculate mean distance ruler fell
*conversion table shows reaction time in Seconds using mean distance
-person drink caffeinated drink + after 10 mins repeat
4 control variables for RP reaction time
what else u should make sure x1
*- how else can u do this experiment
*- pros of testing like this instead
-same person catching
-same hand to catch
-always drop from same height
-person tested X had caffeine before experiment
-person X have more caffeine after- has side effects
-computer tests- eg click mouse as soon as they see a stimulus
-more precise- remove human error
-more accurate- time in milliseconds
-person can’t predict when to respond by reading body language
what is brain made of + control
3 parts of the brain + where they are
billions of interconnected neurones- controls complex behaviour
-cerebral cortex- front (outer wrinkly bit)
-mudulla- front of line going down from brain
-cerebellum- back- fuzzy ball in sack under wrinkly bit
what does cerebellum, cerebral cortex + medulla each do
-cerebral cortex-responsible for consciousness,intelligence, memory, language
-medulla-controls unconscious activities eg breathing
cerebellum- responsible for muscle contraction
3 methods used to study brain+ explain
-studying patients with brain damage-
certain part of brain damaged, effects on patient tell us what that part has to do with
-electrically stimulating different brain parts
put tiny electrodes in brain tissue and zap w/ electricity. See what this causes- gives idea on what that part does.
-MRI scans- produce detailed pic of brain structure- find which parts active when doing certain things eg recalling memory
difficulties investigating brain function/treating brain damage+ disease. x2
Pro of knowing how brain works from investigating
-brain complex + delicate-
difficult to investigate + treat brain
-risk of physically damaging brain + causing more problems
-allows development of treatment for disorders of the nervous system
what is the eye
name all 9 parts of eye
salty cats in palaces love rainbows cos sun out
a sense organ
Sclera
Cornea
Iris
pupil
Lens
Retina
Ciliary muscles
Suspensory ligaments
Optic nerve
describe what these do:
Sclera
Cornea
Iris
pupil
Lens
sclera- tough supporting wall/tissue
cornea-transparent layer @ front of eye- refracts light into eye
iris-has muscles to control diameter of pupil- how much light enters eye
pupil- hole in middle of eye
lens-focuses light on retina
describe what these do:
Retina
Ciliary muscles
Suspensory ligaments
Optic nerve
retina-contains receptor cells sensitive to light+colour
Cilliary muscles-controls shape of lens
suspensory ligaments- controls shape of lens
optic nerve-carries impulses from receptors to brain
-what happens when bright light shone in eye
x3 points
-harm of bright light=
-light receptors detect light and send impulse to brain
-brain sends impulses to muscles in iris .reflex triggered- pupil made smaller
-circular muscles in iris contract + radial muscles relax. -reduces amount of light that can enter
-damage retina
3 alternatives to glasses
contact lenses
laser eye surgery
replacement lens surgery
what happens to eye in dim light x3
-why
radial muscles contract
circular muscles relax
pupil becomes wider
-light receptors in retina sense low light
sends electrical impulse to brain
brain sends impulses to muscles in iris
what is accommodation in eye
To focus on a near object: x3
changing shape of the lens to focus on near or distant objects
-ciliary muscles contract
-suspensory ligaments loosen
-lens becomes thicker (curved) + refracts light more (strongly)
To focus on a distant object: x3
*ciliary muscles relax
*suspensory ligaments pulled tight
* the lens pulled thin + only slightly refracts light rays
what is Hyperopia-
- why does it happen
-what happens
-what lenses correct it- -what do they do
-longsighted x focus close
-lens wrong shape/ doesn’t refract light enough OR eyeball too short
- near object image brought into focus behind retina
-convex lens (curves out)
-refract light rays to focus on retina
what is myopia
- why does it happen
-what happens
-what lenses correct it- what do they do
-short sighted-x focus far
-lens refracts light too much OR eyeball too long
-images of distant objects brought into focus infront of retina
-concave lenses (curve inwards)
-refract light rays to focus on retina
3 alternatives to glasses- briefly describe
-pros of contact lenses and different types
-disadvantage of each surgery
-contact lenses- thin lenses on eye surface
lightweight,almost invisible, convenient
hard lenses OR soft lenses- more comfy, higher risk of infection
-laser eye surgery-
change cornea shape w/ laser- change power of refraction
-laser eye-risk of complications eg infection
-replacement lens surgery-replace lens with plastic one- more effective in long sightedness
-replacement lens-more risky than laser eye-could damage retina-
(+infection)
what does the thermoregulatory centre do-
where is it
what does it contain
where does it recieve impulses from
monitors + controls body temp -
-in brain
-contains receptors sensitive to temp of blood flowing through brain
and
-gets impulses from receptors in skin that give info on skin temp
describe how body temp controlled via negative feedback if too high 3 points
And then if too low. 3 points
-temp receptors detect temp is too high/low
-thermoregulatory centre recieves info and + triggers effectors
-blood vessels dilate, sweat produced to counteract change
-OR blood vessels constrict , sweating stops, skeletal muscles shiver
*what are antagonistic effectors
effectors that do opposite things at same time to keep precise temp levels. This allows more sensitive response
3 mechanisms that lower body temp
explain 2 of them
hairs flatten, sweat, vasodilation
-sweat gland produce sweat- evaporates from skin + transfers energy to environment
-blood vessels dilate - more blood flows close to skin surface, more energy transferred to environment
4 mechanisms that increase body temp
-explain them
-hairs stand up
-sweating stops
-vasoconstriction
-skeletal muscles contract(shiver)
-hairs stand up- trap insulating layer of air
-sweating stops- reduce energy lost
-blood vessels constrict + close off skins blood supply
-shivering needs respiration which transfers some energy to warm body
-what are hormones +
how do they get to target organs
-differences of hormones to nerves x2
chemicals secreted by endocrine glands directly into blood stream. carried by blood to target organ(to produce an effect)
-effects slower, effects last longer, act in more general way (nerves act on precise area)
what gland is ‘master gland’ -what does it do
-why is it ‘master gland’ x2
pituitary gland-
secretes hormones to regulate body conditions-
-these hormones act on other glands
-directs other glands to release hormones that bring a change
-6 parts of endocrine system u need to know
-what do they produce and the purpose of these.
*pituitary gland-hormones-that act on other glands
* pancreas-insulin-regulate blood glucose levels
* thyroid-thyroxine-regulates metabolism rate, heart rate, temp
* adrenal gland-adrenaline -prepares fight/flight response
* ovary-oestrogen-involved in menstrual cycle
* testes-testosterone-controls puberty/ sperm production in males
-organ that controls blood glucose concentration
-what happens when blood glucose levels too high x3
pancreas
produces
-insulin secreted by pancreas
-insulin causes glucose to be taken in by cells out of blood
-In liver + muscle cells,excess glucose converted + stored as glycogen
(so blood glucose reduced)
what happens when blood glucose conc. too low x3
.
.
.
what do glucagon and insulin form
eating what type of food increases glucose levels
-glucagon secreted by pancreas
-glucagon triggers liver cells to convert glycogen into glucose
-liver releases glucose into blood.
(blood glucose level increases)
-negative feedback cycle bcse they have opposing effects
-carbs (type of sugar)
-what is type 1 diabetes- common treatment
-what is type 2 diabetes
- what is a risk factor
-common treatments
-pancreas X produce enough insulin
-insulin injections
(helps to limit carb intake+ excercise)
-body cells X respond to insulin pancreas produces
-obesity
-carb-controlled diet
-regular exercise- removes excess glucose in blood
insulin injection-
things u know about it
how does it help
-very effective
-several injections
-mainly meal time-
-makes sure glucose removed quickly once food digested
-stops level getting too high
how do kidneys carry out their function x2
-filter waste products out of blood
-blood reabsorb useful substances to produce urine (selective reabsorption) eg water, glucose, ions
(basically all glucose is reabsorbed. barely any in urine)
-how is urea made starting with protein digestion x5
-what happens to urea made in liver x3
-digesting proteins=excess
amino acids- can’t be stored
-in liver, deamination happens
-amino acids broken down+stored
- ammonia is by-product of deamination
- Ammonia = toxic
quickly converted to urea-
-urea sent to kidneys in blood
-filtered out
-excreted in urine
-what happens to ions you take in from food. 1 eg
-what happens if water/ion content in body wrong
x2
-where are ions+ urea lost from x2
-where is water lost from x3
-how do we balance amount of water in body x2
how do we balance amount of ions in body x1
absorbed into blood- eg sodium
-too much/ too little water enters cells by osmosis
-cells dont work properly/ damaged
-skin in sweat -kidneys urine
-exhalation, sweat, kidneys in urine
-consume water, remove water in urine
-Kidneys- reabsorb ions / remove them
-water level/ urine concentration controlled by hormone…
-this is released into….. from ……
- The hormone is released when….
- What does this hormone do
–this process is controlled by x2
-ADH hormone-
-released into bloodstream from pituitary gland
-when blood is too concentrated
-causes kidney tubules to become more permeable so more water reabsorbed into blood from kidney tubules
(increases blood water content and urine concentration
- brain(receptors monitor water content in blood)
-negative feedback
what happens when blood water content too high x3
-receptor in brain detect level too high
-Coordination centre in brain receives info + coordinates response
-pituitary gland release less ADH- Kidney tubules less permeable, less water reabsorbed into kidney tubules
what happens if kidneys X work right x2
2 ways to keep kidney failure person alive
-waste substances build up in blood
-X control ion+ water levels in body - eventual death
dialysis, kidney transplant
-Describe how dialysis works-4
-why are useful substances not lost from blood
-how often
-down sides x3
- positive
-blood flows btwn partially permeable membrane- not permeable to large molecules (like membrane in kidney) (eg protien)
-and dialysis fluid- same conc. of ions+ glucose as healthy blood
-waste substances diffuse across
-useful substances X lost from blood- no concentration gradient- fluid +persons blood have same levels of useful substances
-3 times a week for 3/4 hrs
-risk blood clots/ infections
-unpleasant experience
-costly for NHS
—- allows valuable time till donor organ found
-who are kidney transplants taken from x2
-risks x2
- why is transplant better than dialysis x2
-con
-ppl who died suddenly + r on donor register/have donor card (their relatives must agree too)
-ppl still alive
(kidneys ideally matched by blood type)
-small risk to donor
-kidney rejected by immune system- treated w/ to drugs prevent this- can still happen
-cheaper in long run
-X spend hours on dialysis
-long waiting list for kidneys
female reproductive hormone+what it does
male reproductive hormone+ what it does
reproductive hormones cause……… ……. …… to develop
oestrogen- causes physical changes+involved in menstrual cycle
testosterone-stimulates sperm production
-secondary sex characteristics
4 stages in menstrual cycles
1- menstruation starts-uterus lining breaks down for 4 days
2- day 4-14 uterus lining builds up to layer of blood vessels- ready to receive fertilised egg
3-Ovulation-egg develops and released from ovary on day 14
4- wall maintained for 14 days. if fertilised egg doesn’t land on uterus wall, cycle starts again
4 hormones involved in menstruation in order and what they do( not hormones they stimulate)
what happens when progesterone level falls
-FSH-causes maturation of egg
-Oestrogen-causes uterus lining to grow
-LH stimulates release of egg (day 14)
-Progesterone- maintains uterus lining during second half of cycle (after egg released)
level falls-lining breaks down(cycle restarts)
2 menstrual hormones
produced in pituitary gland
2 menstrual hormones produced in ovaries
-what hormone does FSH stimulate ovaries to produce
-what does oestrogen stimulate + inhibit
-what hormone does LH inhibit
-what does progesterone inhibit
FSH
LH
progesterone
oestrogen
FSH stimulates-oestrogen
Oestrogen- stimulates LH, Inhibits FSH
LH -X inhibit or simulate any hormone
Progesterone- inhibits release of LH + FSH
6 methods of contraception-
oral contraceptives
injections/implants/skin patches
barrier methods
intrauterine devices
spermicidal agents
abstaining
surgery
what hormones are in oral contraceptive pill.
how do both these hormones reduce fertility
How do they do this individually
progesterone + oestrogen
-both inhibit FSH so no eggs mature
progesterone- stimulates thick mucus-preventing sperm reaching egg
oestrogen- if taken everyday to keep level high-inhibits FSH production. Eventually egg X develop + FSH X produced
1pro + 2cons of combined oral contraceptive pill (progesterone + oestrogen)
-over 99% effective
-side effects- headaches, nausea
-X protect against STD’s
what pill is better than the combined oral contraceptive pill—
why—
Progesterone only pill- same effectiveness, less side effects
what is the contraceptive patch.
how long does it last
-small patch w/ oestrogen + progesterone stuck to skin. Lasts 1 week
describe contraceptive implant
how long does it last
implant inserted under arm skin. continually releases progesterone .
last for 3 yrs
describe contraceptive injection
how long does it last
-injection w/ progesterone
-lasts for 2-3 months
what is an Intrauterine device-
what does it do-
what are the two types-
- T shaped device put in uterus
kills sperm + stop fertilised egg being implanted
-Plastic IUD release progesterone
-Copper IUD stop sperm surviving in uterus
what do all barrier methods do
3 methods of barrier contraception
stop sperm getting to egg
-Condoms-Male/Female
-Diaphragm (used w/ spermicide)
-Spermicide- used alone
-what do condoms do
-a pro of condoms
-what is a diaphragm
what is spermicide-
con of spermicide-
-prevent sperm entering vagina
-only contraception that protect against STD’s
-plastic cup put over cervix as a barrier. used with spermicide
spermicide-substance that kill/disable sperm
-not very effective when used alone
-describe Sterilisation to stop having a child
-important thing to remember with this method
cut/tie fallopian tubes or sperm duct
permanent procedure- very small chance tubes can rejoin
3 ways other than barrier + hormonal methods
what is ‘natural method’
pro
con
sterilisation, abstinence, natural methods
find out when in cycle woman is most fertile + avoid sex
-popular w/ ppl who think barrier+hormonal methods r unnatural
-not very effective
what is in the ‘fertility drug’ given to women
-why is it given
-how does it help-
-pro of ‘fertility drug’
-cons x2
FSH, LH
woman has low FSH - eggs X mature– no eggs released (by LH) + can’t get pregnant
-stimulates ovulation
-woman can become pregnant in normal way- effective
-X always work- may have to do it many times- expensive
-too many eggs stimulated- unexpected multiple pregnancy
why is IVF used-
4 steps to IVF-
if ‘fertility drug’ or medication X work
*give mum FSH + LH to stimulate maturation
of several eggs.
* eggs collected + fertilised by fathers sperm in lab OR sperm injected into egg (if man has low sperm count)
* fertilised eggs develop into embryos in incubator
* When embryos are tiny balls of cells, 1 or 2 inserted in mothers uterus/womb
pro of IVF
3 cons and describe these
can give infertile couple child
-emotionally + physically stressful (vomit, abdominal pain, dehydration)
-low success rate-upsetting if multiple failures
-lead to multiple births-risky for mum+ babies (<risk miscarriage, stillbirth)
what has helped IVF success rate
what tools have been developed, how do they help
how does time lapse imaging help
advanced microscopy techniques help Improve IVF techniques + so success rates
micro-tools- used on egg and sperm + remove cells from embryo for genetic testing
monitor embryo growth to identify ones likely to cause successful pregnancy
why r ppl against IVF
x2
-results in many unused embryos- destroyed
Unethical as each embryo is a potential life
-ethical issues on genetic testing before implanting. Could lead to selection of preferred characteristics
when is adrenaline released
where are adrenal glands
What does adrenaline do x3
-times of stress/ fear
-above kidneys
-increases heart rate
-boosts supply of O2 + glucose to brain cells + muscles
-preparing body for fight/flight
how is adrenaline released x3
body controls levels of hormones in blood using….
-brain detects fear/ stress
-sends nervous impulses to adrenal glands
-glands respond + secrete adrenaline
negative feedback
where is the thyroid gland
what does thyroxine do x2
in the neck
-regulates basal metabolic rate- speed that chemical reactions occur when body is resting
-stimulates protein synthesis for growth + development
thyroxine is released in response to which hormone.
where is this hormone released from-
what is thyroxine made of-
TSH (thyroid stimulating hormone)
-pituitary gland
-iodine+amino acids
describe how negative feedback is used to control level of thyroxine in blood x3
when level higher than normal-
-secretion of TSH from pituitary gland is inhibited
Less thyroxine released from thyroid
level of thyroxine in blood falls
what is auxin,
how does it produce desired results-
what does it control
plant hormone-
-promotes growth near tips of shoots+ inhibits growth in roots
-controls growth in response to light-(phototropism) and gravity ( gravitropism)
where is auxin produced, where does it move to, why
-produced in tips. moves backwards for cell elongation process (occurs behind tips)
what happens if tip of shoot removed
-what happens when shoot tip exposed to light 3 points
no auxin available so shoot can stop growing
-more auxin accumulates on shaded side
-cells elongate/grow faster on shaded side
-so shoot bends towards light
what happens when shoot is growing sideways- 3 points
-gravity produces unequal auxin distribution in tip- more on lower side
-lower side grows faster
-shoot grows upwards
what happens when root is growing sideways- 3 points
-gravity produces more auxin on lower side
-extra auxin inhibits growth so cells on top elongate faster
-cell bends downwards
RP effect of light on growth
x7
-10 seeds in 3 labelled petri dishes
-line each w/ moist cotton wool
-let seeds germinate in warm place
-make sure same amount have germinated in each dish, if not, remove some so equal number
-measure height of each seedling and work out mean for each dish
-place in different conditions
-work out new mean for each dish
RP effect of light on growth
-what is independent variable
what are the 5 control variables- explain how to control them
light
no.of seeds-use same no.
type of seeds-seeds from same packet
temp-keep petri dishes in stable temp
water-add same amount of water to dampen cotton wool. water them w/ same amount each day
light intensity- distance btwn seed and bulb the same
what are three different conditions for RP effect of light on growth
what are the effects on growth x3
full sunlight
in box with partial light
darkness
-full light + partial light grow similar height
-partial light bent to light
-darkness- grow longest- bcse they grow rapidly to reach light
-darkness- leavs small/yellow-X photosynthesise
Rp effect of gravity on plant growth
3 steps
-place seedlings on damp cotton wool in petri dish with roots pointing in different directions
-store vertically in dark
-all roots will grow down
uses of auxins x3
explain them
-weed killers
Weedkillers developed using auxins -disrupt growth of broad leaved plants (weeds) -kill them
-rooting powders-contain auxins. Added to cuttings, roots produced quickly and grow as new clone plants
-promoting growth in tissue culture-auxins added to growth medium -plant cells divide into roots +shoots
what are giberellins, what do they do x3
what is ethene
what does it dox2
plant growth hormone
stimulates seed germination, stem growth, flowering
-gas produced by aging plant parts
-effects growth by controlling cell division
-stimulates enzymes that cause ripening
Gibberellins can be used to: x3
describe each
- end seed dormancy
- promote flowering
- increase fruit size.
some Seeds X germinate till been through certain conditions - dormancy. Giberellins alter dormancy- make seeds germinate at different time- all seeds in batch germinate together
some plants need certain conditions to flower. Treated w/ gibberellin- flower w/out change in environment + grow bigger flowers
-seedless fruit grow smaller than seeded.Gibberellins increase growth to match seeded type
use of ethene.
what do some fruits do as they ripen?
used in food industry to control fruit ripening during storage+transport.
-produce more ethene
a pro of using ethene to ripen fruit
fruit picked when unripe, less fragile, gas added on way to store
what is the cns
what is a coordination centre
CNS- brain + spinal chord (where reflexes + actions are coordinated)
Coordination centre- An organ that processes info from receptors and organises response from effectors
