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)
