T5 - Homeostasis and response Flashcards
What is homeostasis?
regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.
What does homeostasis control in human body? x3
- blood glucose concentration
- body temperature
- water levels.
Feature of homeostasis systems?
automatic
what do automatic control systems involve?
nervous or chemical responses
Features of automatic control system? x3
-receptor cells
-coordination centre
-effector
What do receptor cells do?
detect stimuli
What is a stimulus?
change in environment
What do coordination centres do?
receive and process information from receptors
What do effectors do?
carry out response to restore optimum level
What is the role of the nervous system?
enables humans to react to their surroundings and to coordinate their behaviour.
Process of reflex arc? x7
- receptor detects stimulus
- electrical impulses go through sensory neurone from receptor to CNS
- synapse releases chemical which diffuses to a relay neurone in CNS
- electrical impulse travels across relay neuron and reaches synapse
- chemical is released and triggers impulse in motor neurone
- impulse goes down motor neurone to effctor
- effector now responds
Transition of reflex arc?
receptor—sensory neurone—CNS—relay neurone—motor neurone—effector
Feature of reflex actions? x2
-automatic and rapid
-unconscious reaction
Functions of cerebral cortex in brain? x3
-language
-memory
-consciousness
Function of cerebellum in brain? x2
-controls balance
-coordinates movement
Function of medulla in brain ? x2
-controls heart rate
-controls breathing rate
Parts of the brain? x3
-cerebral cortex
-cerebellum
-medulla
why is it hard to study the brain and treat brain damage? x3
-protected by skull
-brain is complex
-brain is delicate
Ways that scientists investigate brain? x3
-look where brain damage takes place
-electrically stimulate pats of brain
-MRI scan to see which part of brain is active
Function of cornea in eye?
start focusing of light rays
function of lens in eye?
focus light rays onto back of eye
What does the retina contain?
receptor cells
What do receptor cells in retina allow us to do? x2
-detect light intensity
-detect light colour
function of sclera in eye?
protect eye
function of ciliary muscles and suspensory ligaments?
allow us to focus on near or distant objects
function of pupil?
allows light rays to pass into eye
Function of iris?
control size of pupil
What is accommodation?
process of changing shape of lens to focus on near or distant objects.
What happens when the eyes needs to focus on distant objects? x3
- ciliary muscles relax
- suspensory ligaments pulled tight
- the lens is then pulled thin and only slightly refracts light rays.
What happens when the eyes needs to focus on near objects? x3
- ciliary muscles contract
- suspensory ligaments loosen
- the lens is then thicker and refracts light rays strongly.
What lens fixes long sightedness?
convex lens
What lens fixed short sightedness?
concave lens
New technology that fixes long and short sightedness? x3
-hard and soft contact lenses
-laser surgery
-replacement lens in eye
What does laser surgery do?
change shape of cornea
Where is body temperature monitored and controlled?
thermoregulatory centre in the brain
What does thermoregulatory centre contain?
temperature receptors
Feature of temperature receptors in thermoregulatory centre?
sensitive to temperature of blood
What does temperature receptors in skin do?
send impulses to the thermoregulatory centre
What happens when body temperature gets too high? x2
-sweat is produced from sweat glands
-vasodilation near skin
Why do capillaries near skin vasodilate if the body temperature gets too high?
to transfer heat out of blood
why do sweat glands produce sweat when body temperature gets too high?
to transfer energy out of body
What happens when body temperature gets too low? x
-vasoconstriction
-sweating stops
-shiver
Why do capillaries near skin vasoconstrict if the body temperature gets too low?
to reduce heat loss out of blood
Why do we shiver when body temperature gets too low?
to increase rate of respiration to release heat
Why do we stop sweating when body temperature gets too low?
to reduce energy loss
What is endocrine system composed of?
glands
What do glands do?
secrete hormones into bloodstream
main feature of each hormones?
only acts on specific target organs
Difference between endocrine system and nervous system? x2
-endocrine system has slower effects
-endocrines system effects are longer lasting
What does pituitary gland do?
secretes several hormones into blood in response to body conditions
What do hormones released by pituitary glands do?
act on other glands to stimulate other hormones to be released
What is blood glucose concentration monitored and controlled by?
pancreas
What does the pancreas produce if blood glucose concentration is too high?
insulin
What does insulin do?
makes glucose go from blood to cells
What happens in type 1 diabetes?
pancreas doesn’t produce enough insulin
What is type 1 diabetes controlled with?
insulin injectors
What happens in type 2 diabetes?
cells stop responding to insulin produced
What is type 2 diabetes treated with?
diet and exercise
Risk factor for type 2 diabetes?
obesity
What does the pancreas produce if blood glucose concentration is too low?
glucagon
What does glucagon do?
converts glycogen back to glucose and releases it into blood
Where does water go if blood gets too dilated?
from blood into cells
Where does water go if blood gets too concentrated?
from cells to blood
Ways body loose water? x3
-exhalation
-sweat
-urine in kidneys
What happens if cells gain or loose too much water by osmosis?
doesn’t function efficiiently
Does the body have control over water, ion or urea loss by the lungs or skin?
no
In which ways is ions and urea also removed with water? x2
-sweat
-urine
process of kidneys? x4
-artery bring blood to kidney
-kidney removes urea water, ions and glucose
-all glucose and some of water and ions is reabsorbed back into blood
-urea, excess water and ions are released as urine
What happens to excess amino acids in the liver?
amino acids are deaminated to form ammonia
What is deamination?
when amino acids are broken dwn to form ammonia
Why must ammonia by immediately converted to urea?
ammonia is toxic and needs to be excretes safely
Where is ADH releases fom?
pituitary gland
WHat does ADH do in kidneys?
allows more water to be reabsorbed into blood from tubules
Treatment for kidney failure?
-kidney transplant
-kidney dialysis
What happens when someone has kidney failure?
they have higher concentration of water, ions and urea then they should
How does kidney dialysis work? x4
-blood passes over a semi permeable membrane
-this allows urea, ions and water through but not larger molecules
-dialysis fluid has a low concentration of urea so urea diffuses through
-dialysis fluid is constantly refeshed
Why is dialysis fluid constantly refreshed?
for large concentration gradient for urea
How is kidney dialysis inconvenient? x2
-visit hospital several times a week
-controlled diet
advantage of kidney transplant? x2
-allows patient to live normal life
-only expensive initially
disadvantage of kidney transplant? x2
-shortage of kidney donors
-need to take anti-rejection drugs for rest of life
advantage of kidney dialysis? x1
disadvantage of kidney dialysis? x2
-requires frequent hospital visits and controlled diet
-expensive long term
What does testosterone do?
stimulate sperm production
Where is testosterone found?
testes
What is ovulation?
When an egg mature and releases every 28 days
Where is oestrogen produced?
ovaries
What is the function of FSH?
causes egg to mature in ovary
What is the function of LH?
causes egg to be released
Function of Oestrogen and progesterone?
to maintain uterus lining
process of menstrual cycle? x7
-FSH releases by pituitary gland and causes egg to mature
-FSH makes ovaries produced oestrogen
-Oestrogen makes lining of uterus thick
-Oestrogen stops production of FSH
-LH releases the egg
-Progesterone is released and stops production of FSH and LH
-Proesterone keeps lning of uterus thick
What do oral contraceptives do?
stop production of FSH
Advantage of oral contraception? x1
-effective
disadvantage of oral contraception? x3
-must be take everyday
-increase risk of breast cancer or blood clots
-doesnt protect against STI
Advantage of injection, implant or skin patch?
-convenient (lasts longer)
What does an injection, implant or skin patch of progesterone do?
stops eggs maturing or being released
disadvantage of injection, implant or skin patch? x2
-can have side effects
-doesnt protect against STIs
What does barrier method do?
stops sperm reaching egg
Advantage of barrier method? x2
-dont have side effects
-reduce risk of STIs
disadvantage of barrier method? x1
can break or slip off
What do spermicides do?
kill or disable sperm
What does an intrauterine devices do?
prevent embryo from implanting
Advantages of intrauterine devices? x2
-effective
-few side effects
disadvantage of intrauterine devices? x
-Doesnt protect against STIs
What is sterilisation?
surgical method of contraception
WHat does sterilisation do in women?
prevents egg from reaching uterus
What does sterilisation do in men?
prevents sperm from leaving penis
advantage of sterilisation? x1
-effective
disadvantage of sterilisation? x2
-hard to reverse
-doesnt protect againnst STIs
Disadvantage of abstaining from intercourse during time after ovulation? x
-hard to tell when a women ovulated
-doesnt protect against STIs
What is a fertility drug?
LH and FSH given to women
process of IN Vitro Fertilisation(IVF)? x5
-LH and FSH given to mother
-eggs collected from mother
-sperm collected from father
-sperm fertilised with eggs in laboratry
-embryo inserted into mothers uterus
Advanatage of IVF? x1
gives women chance to have a baby
disadvanatage of IVF? x4
-low success rate
-can lead to multiple births
-stressful for parents
-expensive
When is adrenaline produced?
times of fear or stress
Effects of adrenaline? x2
-increases heart rate
-boots delivery of oxygen and glucose to brain and muscles
Effects of thyroxine? x2
-stimulates the basal metabolic rate
-needed for growth and development.
What is phototropism?
when plant shoot grow towards light
How dos auxin work in phototropism? x4
-auxin produced at tip of shoot
-light causes auxin to concentrate on darker side
-auxin spread down the shoot so cells on darker cells grow faster
-shoot grows towards light
What do auxins do?
trigger cell growth
What is gravitropism?
when plant roots grow towards force of gravity
How do auxins work in gravitropism?
-gravity causes auxin to go down
-lower side grows slower
-roots grow towards gravity
-
Function of Gibberellins?
start seed germination.
Function of Ethene?
controls cell division and ripening of fruits.
Uses of auxin? x3
-weedkillers
-rooting powders
-promoting growth in plotting culture
Uses of gibberelins? x3
-end seed dormancy (force seed to germinate earlier than normal)
-encourage plants to flower
-increases fruit size
Uses of ethene? x1
control ripening of fruit
