Homeostasis and Response Flashcards
what is homeostasis ?
maintaining a stable internal environment
why do are internal conditions need to be kept the same?
cells and enzymes require specific conditions to function
what make up the automatic control system?
- receptors
- coordination centre
- effector
what do multi cellular organisms do that single-celled organisms do?
multi cellular organisms have cells that communicate
what do the receptors do ?
detect stimuli
what do the effectors do?
respond to the impulses
what connects two neurones ?
synapse
what are reflexes?
rapid and automatic responses that don’t involve the conscious part of the brain
what is the path a impulse travels for a response?
- STIMULUS
- SENSORY NEUTRON
- SYNAPSE ( between sensory and relay)
- RELAY
- MOTOR NEURON
- EFFECTOR ( eg. muscle )
what is the investigation for reaction time ?
ruler 2 people
what is a more precise way of measuring reaction time ?
computer test
- reduces human errror
what is the cerebral cortex for?
- outer wrinkly bit
- consciousness
- memory
what is the medulla?
- unconscious activity
what is the cerebellum ?
muscle coordination
how can scientist study the brain?
- MRI scan
- electrically stimulating the brain
- studying patience with brain damage
what are the consequences of the electrical stimulation on the brain?
can increase problems with brain function and physical damage
what is the sclera ?
tough and supporting wall of the eye
what is the cornea ?
transparent outer layer
what is the iris ?
muscles that controls how much light goes into the eye
what is the lens ?
focuses light onto the retina
what controls the shape of the lens ?
- CILIARY MUSCLES
- SUSPENSORY LIGAMENTS
what is the optic nerve ?
carries impulses from the receptor on the retina to the brain
what happens to the eye when there is too much light?
- pupil smaller
- circular muscles contract
- radial muscles relax
how does the eye focus light on the retina ?
CHANGING the shape of the LENS
how does the eye focus on objects near to it ?
- ciliary muscles contract
- suspensory ligaments slacken
- lens becomes fatter
what can be used to treat vision defects?
contact lens
laser eye surgery
replacement lens surgery
what happens to you body when you hot?
- hair lies flat
- sweat is produced by the sweat glands which is evaporated from the skin
- blood vessels dilate so there’s more blood closer to the skin surface
what are hormones ?
chemical messengers sent through the blood
what are examples of endocrine glands ?
- pituitary glands
- thyroid
- adrenal glands
- pancreas
- testes
- ovaries
what are the difference between hormones and nerves?
nerves are faster and act for a very short time on a precise area where as hormones are the opposite
nervous responses are QUICK
hormonal responses last a LONG TIME
what controls blood glucose levels ?
INSULIN and GLUCAGON
what impact does eating carbohydrates have?
puts glucose into the blood from the gut
how is glucose removed from the blood?
metabolism
exercise
stored as glycogen
negative feedback cycle
what monitors and controls levels of glucose ?
PANCREAS
what is released when glucose level is too high ?
INSULIN is released by PANCREAS which moves form the blood into the LIVER which turns glucose into glycogen
what happens when glucose levels are too low ?
GLUCAGON is released by the PANCREAS which moves from the blood into the LIVER where it is turned into GLUCOSE
what is type one diabetes?
- little or no insulin made
- insulin therapy which stops glucose levels getting too high
what is type two diabetes ?
- become resistant to their own insulin
- increasing glucose levels
- obesity is a huge risk factor
- can be controlled by exercise and carbohydrate diet
what is the role of the kidney ?
- acts a s a FILTER for the BLOOD
- makes urine out of waste products
- selective reabsorption
what is removed in the urine ?
urea (ammonia)
ions (osmosis)
water
what controls the concentration of urine ?
ANTI-DIURETIC HORMONE (ADH)
how much water is reabsorbed by the kidney
where is adh released from ?
from the pituitary glands into the bloodstream
what is used in the case of kidney failure?
DIALYSIS
a persons blood flows between a partially permeable membrane surrounded by dialysis fluid
it allows waste substances to be diffused
what are the negative aspects of dialysis ?
- expensive
- 3-4 hours 3 times a week
- can cause blood clots or infection
what is the “cure” for kidney failure ?
at the moment the cure is a kidney transplant which can sometimes be rejected by the patients immune system but overall is cheaper than dialysis in the long term
what are the 4 stages of the menstrual cycle ?
- menstruation starts
- uterus lining builds up
- egg develops and is released
- wall is maintained
what are the hormones involved in menstruation ?
- FSH
- OESTROGEN
- LH
- progesterone
what is FSH ?
produced by pituitary glands
cause egg to mature
stimulated production of oestrogen
what is oestrogen ?
produced in the ovaries
cause lining of uterus to grow
stimulates release
what is LH?
produced in the pituitary gland
stimulates egg release
what is progesterone ?
produced in the ovaries
maintains the uterus lining
prevents the release of LH and FSH
what hormone can be used to reduce fertility?
- oestrogen
prevents the release of the egg and inhibits production of FSH - progesterone
stimulates mucus which prevents sperm reaching an egg
what are the main hormone contraceptive methods ?
- contraceptive patch
contains oestrogen and progesterone - contraceptive implant
inserted into the arm and releases a continuous amount of progesterone which stops release of an egg, lasts 3 years - contraceptive injection
contains progesterone lasts 2-3 months - IUD
t shaped device inserted into the uterus that kills sperm
either plastic that releases progesterone or copper that prevents sperm surviving
what makes up the pill?
oestrogen and progesterone
combined oral contraceptive pill
what are non-hormonal forms of contraception ?
- barriers
condoms/ diaphragm/ spermicide - sterilisation (tying the Fallopian tubes)
- avoiding intercourse
what hormones can be used to INCREASE fertility ?
FSH and LH stimulate ovulation
can be expensive or cause multiple unexpected pregnancy
what is IVF ?
- collect eggs form women’s ovaries
- fertilised in a lab
- embryos grows in the lab incubator
- transferred into the incubator
what are the negative aspects of IVF ?
multiple births
can also have multiple failures
bad side effects
expensive
what is adrenaline ?
a hormone
released in response to stressful of scary situations
“fight of flight”
increases supply of OXYGEN and GLUCOSE to the brain and muscles
what is thyroxine ?
regulates metabolism
what is auxin ?
- a plant hormone that controls growth
- produced in the tip
how does light effect the growth of a plant?
the PHOTOTROPISM causes auxin to accumulate in shaded areas of the plant and elongate towards the light
how does gravity effect the growth of shoot ?
the GEOTROPISM causes an uneven distribution in the tip with more auxin on the lower side causing it to grow faster and the plant to grow upwards
how does gravity effect the growth of the root ?
there is more auxin in the under side like the shoot however in the root it inhibits growth causing the outer side to grow faster and the root to grow downwards
what are some commercial uses of auxin ?
- killing weeds
- growing from cuttings
- growing cells in the tissue culture
what is gibberellin ?
stimulates the growth of a plant stem
what is ethene ?
stimulates ripening of fruit
