homeostasis and response Flashcards
what is homeostasis?
Homeostais is the regulation of internal conditions in a cell or organism to maintain optimum conditions for function in response to internal and external changes.
what does homeostasis control?
3
- blood glucose concentration
- body temperature
- water levels
what do the automatic control systems include?
and what do they do?
- receptor- they detect stimuli
- coordination centres- process info given from receptors (spinal cord, brain, pancreas)
- effectors- bring about responses that restore optimum levels (muscles/glands)
what does the nervous system do?
and what does it consist of?
- allows reactions to environments and co-ordinates behaviour
-Central Nervous System (brain & spinal cord)
-Peripheral Nervous System (all nerves)
Structure of neurones
- axons- carry impulses
- myelin sheath- insulates axons to prevent short circuits
- dendrites- branches off cell body and recieve impulses
pathway through nervous system
stimulus -> receptor -> co-ordination centre -> effector -> response
sensory neurone AND motor neurone NOT RELAY
reflex arc
stimulus -> receptor -> sensory neurone -> CNS -> realy neurone -> motor neurone -> effector -> response
DOESNT pass through CONSCIOUS part of brain
automatic
sensory vs relay vs motor neurones
Sensory- long, cell body in middle
Relay- short, NO myelin sheath
Motor- long, lots of dendrites
what is a synapse and how do electrical impulses croos over?
A synapse is the gap between neurones
Chemicals called neurotransmitters diffuse acroos synapse carrying electrical impulse to receptor molecules.
drugs can bind to neurotransmitters
what is the cerebellum?
and where is it found?
responsible for muscle co-ordination and movement
bottom/back of brain
m for muscle and movement
what is the cerebRal cortex?
and where is it found?
responsible for consciousness, memory, intelligence and language
outer part of brain
2 c’s for consciousness
what is the medula?
and where is it found?
responsible for unconsious activity
i.e breathing and heart rate
brain stem infront of cerebellum
m for mindfullness - breathe in slowly reducing heart rate
why is so difficult for neuroscientits to study the brain?
is it incredibly complex and delicate
how can neuroscientists map regions of the brain?
- studying patients with brain damage
- electrically stimulating areas of brain- pushing electrode into brain
- MRI scanning
what temperature do the enzymes in the body work best at?
37
where is the body temperature monitered and controlled?
thermoregulatory system in the hypothalamus
how is a change in temperature dected?
receptor cells in skin detect stimuli and sends impulses to receptors in thermoregulatory system
how does the body cool itself down?
- vasodilation- blood vessels dilate, increasing blood flow to skin- increasing energy transfer
- sweat- evapourates from skin, increasing energy transfer
how does the body warm itself up?
- vasoconstriction- blood vessels constricts to reducing blood flow to skin
- skeletal muscles contract rapidly- shivering- generate heat from respiration
- hairs stand on end- creating insulating layer to trap warm air
what are the two main funcfions of the eye?
-accomadation- focusing on near or distant objects
-adaptation- dimming light
function of the retina?
has light receptor cells (rods and cones) to detect light intensity and colour of light, to send impulses to brain
difference between rods and cones?
cones arent as sensitive to light then rods
function of optic nerve
sensory neurone that carries impulse from eye to brain
function of sclera
white layer that covers eyeball to prevent damage
function of cornea
transparent layer at front of eye that refracts light
function of iris
controls how much light enters pupil
function of ciliary muscles
relaxes and contracts to change shape of lens
function of suspensory ligaments
tightens and loosens to change shape of lens
function of lens
transparent disc that’s shape is changed to focus light onto the retina
what is accomodation?
process of changing the shape of the lens to focus on near or distant objects
to focus on a near object…
- ciliary muscles CONTRACT
- suspensory ligaments LOOSEN
- lens THICKER- refracting light STRONGLY
to focus on a distant object
- ciliary muscles RELAX
- suspensory ligaments TIGHTEN
- lens pulled THIN- refracting light SLIGHTY
distant slightly, distant tighten
myopia
short-sighteness
hyperopia
long-sightedness
where is the rays of light focused with myopia?
infront of retina- eyeball too enlongated
where is the rays of light focused with hyperopia?
behind retina- eyeball too short
concave lens
myopia
caves inwards
convex lens
hyperopia
looks like v
how to treat eye defects?
4
- spectacle lenses
- contact lens
- laser eye surgery- adjusts thickness of cornea (myopia- reduce- less refraction,, vice versa hyperopia)
- replacemnt lens- replaces lens with artificial- hyeropia- risks- cataracts, damage to retina
pituitary gland
- MASTER GLAND
- secretes hormones to act on other glands to stimulate production of other hormones
pancreas
what does if secrete
what does it control
- secretes insulin
- controls blood sugar levels
thyroid gland
what does it secrete
what does it control
- secretes thyroxine
- controls metabolic rate, heart rate and temperature
adrenal gland
- secretes adrenaline
- involved in ‘fight or flight’ response
ovaries
- secretes oestrogen
- involved in menstrual cyle and development of female secondary sexual characteristics
testes
- secretes testerone
- involved in production of sperm an development of male secondary sexual characteristics
what are hormones and where are they carried to?
chemical messengers carried in the blood to the target organ or tissue
if the blood glucose concentration levels are too high
- pancreas produces insulin
- nsulin stimulates liver to convert excess glucose into glycogen & muscle cells to use glucose for respiration
if blood glucose levels are too low
- pancreas produces glucagon
- binds to liver cells to break gycogen down into glucose released into blood
diabetes type 1
pancreas cannot produce enough insulin
uncontrolled blood glucose levels
glucose excreted with urine- thirsty
treated with insulin injections
diabetes type 2
body cells can no longer respond to insulin
obesity- risk factor
treatment- reducing carbs, loosing weight, excersise
too much water in the blood
cell & adh
cells swell and burst
less adh- less water reabsorbed
too little water in the blood
cells & adh
cells shrink
more adh- more water reabsorbed
how does water leave the body?
2
- sweat
- exhalation from lungs
what else leaves sweat
- ions
- water
- urea
deanimation
excess amino acids from digestion of protien
broken down in liver into ammonia
what is urea
ammonia is toxic and so conveted into urea
what is the hormone ADH and what does it do?
- anti diuretic hormone
- CONSTANTLY released from pituitary gland
- controls how much water reabsorbes into kidney tubules
filtration of blood in kidneys
- high pressure causes moevules small enough to move through pores of bloodstream
what is selective reabsorbtion?
and what does it absorb?
- kidneys reabsorbing substances body needs
- ALL glucose
- enough water for constant levels
- enough ioons for constant levels
- NO urea
process of kidney dialysis
unfiltred blood from arm into dialysis machine and returned
dialysis fluid & blood
seperated by partially permeable membrane and goes opposing ways to allow exchange where concenteration gradient exists
fluid:
- glucose similiar to healthy blood
- ions similiar to healthy blood
- no urea
disadvantages of dialysis
- possibility of blood clots forming
- many hours a week
- strict diet
- expensive
disadvantes of kidney transplant
- chance of rejection
- immunosuppresent drugs^ supresses immune system
- ^ vulnerable to other disease
FSH & LH
- follicle stimulating hormone
- luteinising hormone
FSH
- FSH released by pituitary gland to stimulate production of follicle
- egg matures in follicle and follicle produces oestrogen
break down of lining- period
FSH matures egg and stimulates production of oestrogen
oestrogen
- oestrogen causes growth and repair of lining
- inhibits production of FSH
- when high enough- stimulates release of LH from pituitary gland
LH
- results in ovulation
progesterone
- follicle produces progesterone
- maintains uterus lining
- if egg not fertilised- progesterone levels drop- period
chemical contraceptives
- oral contraceptives
- injection/implant/skin patch
- Inrauterine devices- IUD
what do oral contraceptives involve
inhibits FSH production so no eggs mature
two types
- combined- oestrogen^ & progesterone (thick mucuc preventing sperm)
- progesterone- fewer side effects
patch/implant/injection/IUD
- progesterone- thickens mucus of cervix- stops sperm swimming
patch- one week
implant- 3 years
injection- 2 to 3 months
IUD- insterted into uterus
barrier contraceptives
- condoms- prevent spread of STI
- -diaphragms
- spermicidal agents- kills sperm
natural contraceptive
abstaining from intercourse when in ovulation
surgical contraceptives
male and female sterilisation
female- oviduvts cut and tied
male- soerm ducts cut and tied- vasectomy
what hormones are used for infertility?
FSH & LH to stimulate egg production
expensive
how does IVF treatment work?
in vitro fertilisation
- mother- FSH & LH - stimulates maturation of eggs
- eggs collected and fertilised with father’s sperm in lab
- develop into embryos
- 1 or 2 place into mother’s womb
risks of IVF
- low success rate
- several- possible multiple births
- people against- more embryos produced than used
adrenaline production
- procued by adrenal glands in times of fear or stress
- increase heart rate and delivery of oxygen and glucose to brain and muscles- preparing for fight or flight
- pupild dilate- more light- see clearly
thyroxine production
- produced in thryoid to regulate metabolic rate - growth and develoment
- produced by TSH- pituitary
- stimulates BMR (Basal Metablic Rate) & protein synthesis
thyroxine negative feedback
too high- inhibit TSH
too low- TSH
what is negative feedback?
when the body responds to increase or decrease in a factor by returning it back to original level
roots tropisms
NEGATIVE phototropism
POSITIVE gravititropism
shoots tropisms
POSITIVE phototropism
NEGATIVE gravitropism
3 plants hormones
- auxins
- gibberellin
- ethene
auxins in shoots
- goes to shaded side- stimulates growth in cells- shoot bends towards light
- more light= more photosynthesis
- bends not straight
usually evenly distributed at tip
IF horizontal- moves to lower side- more growth- upwards bc + gravitropism
auxins in roots
IF horizontal- moves lower side- less growth- downwards bc - gravitropism
gibberellins
- important in initiating seed germination- when seeds starts to grow
- flowering & growth of fruit
ethene
- gas involved in cell division and ripening of fruits
how are auxins used
- selective weed killers- causes cells to grow too rapidly- death- broad leavves weeds
- rooting powder- plants w desriable featues cloned by taking cutting and using rooting powder to increase growth
- promote growth in tissue culture- ^ another way of cloning- cells from plant into growth medium w nutrients- auxins added
how is ethene used
food industry
- fruit picked unripe as firm so less bruised fom transport- exposed to ethene to stimulate enzymes involved in ripening- more suitable to be sold
how is gibberellins used
- ending seed dormancy- when seed unavble to germinate
- promote flowering- quicker
- increasing fruit size- seedless fruit sprayed- seeds produce g
