Year 10 Test 3 Flashcards
What is homeostasis
Control of constant internal conditions, involves nervous and endocrine system and many organs
What are hormones
Chemical substances
Secreted by glands
Transported to target organ by bloodstream
Pituitary gland
Master gland, produces hormones, some act on other glands e.g growth hormone, FSH, LH, ADH, TSH
Thyroid gland
Thyroxine released which helps to regulate metabolism, heart rate and temperature
Pancreas
Glucagon and insulin produced, both involved in regulating blood glucose levels
Ovaries
Produces progesterone and oestrogen which are involved in menstrual cycle
Testes
Produces testosterone which controls sperm production and puberty
Adrenal gland
Produces adrenaline which prepares body for flight or fight response
What happens if too much water moves into or out of cells
They can be damaged or destroyed
How do minerals and water enter and leave the body
Enter body when eat or drink
Salt lost in sweat, water lost when breathe out and sweat, water and salt lost in urine
What does the concentration of urine produced by the kidneys depend on
Nerves and hormones
What happens if you drink lots of water
Kidneys remove excess water from blood and lots of very pale urine produced
Controlling body temperature
Core body temp 37degrees and surface temp may fluctuate widely but core must stay the same
At only few degrees different enzymes can either denature or slow down reaction as fewer collisions
What can affect body temperature
External temp rising or falling
Fevers caused by disease
Energy produced in muscles from respiration during exercise
Thermoregulatory centre
Located in brain, contains receptors which are sensitive to temp change in blood flowing through brain
Where does the extra info come from about temp
Comes from temp receptors in skin which send impulses to centre giving info about skin temp. Receptors are can detect change of as little as 0.5degrees
Vasodilation
Arterioles dilate so more blood enters the skin surface capillaries and heat is lost
Sweating
Sudofric glands secrete sweat which removes heat when water changes state
Pilorelaxation
This means the hair flattens
Stretching out
By opening up, body has a larger surface area
Vasoconstriction
Arterioles get smaller to reduce blood going to skin, keeping body warm
Shivering
Rapid constriction and relaxing of skeletal muscles. Heat produced by respiration
Piloerection
Hairs on skin stand up, trapping a layer of insulated air
Curling up
Making yourself smaller so smaller surface area
What are responsible for controlling blood glucose levels
Sugar and other carbohydrates
What happens after digestion and then after exercise
Straight away blood sugar levels become very high but after exercise the levels fall again
What keeps the blood glucose levels constant
Insulin and glucagon
What happens when blood glucose levels fall
Glucagon is produced which causes glycogen to be converted into glucose and released into blood
What does insulin do
Causes liver to remove excess glucose from blood and then converted into to glycogen which is stored in liver and muscles
What is the usual amount of glucose in the blood
90mg per 100cm^3 of blood
Cause of type 1 diabetes
Sudden and almost complete inability to produce insulin, often occurs in kids under 15 (early onset)
Symptoms of type 1 diabetes
Severs thirst, weight loss and tiredness usually fairly fast
Treatment for type 1 diabetes
Insulin injections, amount needed deepens on diet and how active the individual is
Cause of type 2 diabetes
Where person becomes resistant to their own insulin meaning it’s unable to move glucose into cells. Main reason being overweight (around belly)
Symptoms of type 2 diabetes
Tiredness, thirst, needs to pass urine more often, some thrush and blurred vision. Affects heart kidneys nerves and eyed. Narrowed arteries
Treatment for type 2 diabetes
Lose weight or given tablets to stimulates insulin production or help body use insulin more effectively
Why is it important to maintain water balance in the body
If balance is upset the cells can be damaged or destroyed e.g. Osmotic balance -> cells shrink or burst
Where does urea come from
Produced in liver by break-down of amino acids this is removed by the kidneys in urine which is temporarily stored in the bladder
What do the kidneys produce
Urine by filtration of blood and selective reabsorption of useful substances e.g. glucose, some ions and water
What moves out of blood and into kidney tubules
Sugar (glucose), amino acids, mineral salts and urea move to kidney tubules by diffusion along concentration gradient
What is left behind
Blood cells and large protein molecules as too large to pass through membrane of tubule
What happens to the sugar
All sugar reabsorbed back into blood by active transport
What happens to the water and urea
Amount of water reabsorbed depends on body’s needs, controlled by sensitive feedback mechanism
Urea lost in urine
Kidneys blood supply and bladder
Rich blood supply and produce urine all of the time. Trickles into bladder where stored until you chose to empty it
What is ADH
Anti-diuretic hormone
What is diuresis
Increases urine production
Water level in the body is controlled by…
ADH which acts on kidney tubule. Released by pituitary gland. When blood too concentrated it causes water to be reabsorbed into blood from tubules controlled be negative feedback
How does dialysis work
Fluid contains same conc. of glucose, mineral ions as body
Urea diffuses into fluid from blood but cells and large proteins can’t pass through dialysis membrane
Restores concentration of substances back to normal
Dialysis and hospitals
Many people got to hospital to receive dialysis but in 1964 home dialysis was made available
Kidney transplants
Donor kidney joined blood vessels in groin of patient.
Chance of rejection as foreign to body so to reduce risk match is made with similar tissue type so antigens similar
Recipient given immunosuppressant
Female reproductive hormones
Oestrogen and progesterone (from ovaries)
LH and FSH (from pituitary gland)
Male reproductive hormones
Testosterone (from testes)
What is FSH
Follicle stimulating hormone - stimulates follicle to mature (a follicle contains an egg)
What is LH
Luteinising hormone
Control of menstrual cycle
FSH secreted by pituitary causing egg to mature and stimulates ovaries to produce oestrogen which is secreted by ovaries and inhibits further production of FSH. Also stimulates lining of uterus to build up and stimulates pituitary to produce LH which stimulates ovulation from 1 ovary in the middle of the cycle
What does progesterone do
From ovary and maintains lining of uterus during middle part of cycle and during pregnancy
Oestrogen only pill
Taken everyday, keeps oestrogen levels permanently high. Inhibits FSH so egg maturation and release stops
Concerns about it causing blood clots
Combines oestrogen and progesterone pill
Progesterone stimulates production of thick cervical mucus which prevents sperm meeting egg Over 99% effective Doesn't protect against STIs Reduces risks of some types of cancer Can cause headaches, nausea
Skin patches, implants and injections
Patch contains oestrogen and progesterone, small and sticks to skin, lasts a week
Implant inserted under skin contains progesterone lasts 3 years
Injection contains progesterone, lasts 2-3 months
Barrier methods
Condom worn over penis, prevents sperm entering
Diaphragm, shallow plastic cup placed over cervix, can be used with spermicide
Spermicide alone not very effective
Intrauterine devices
T-shaped device inserted into uterus and kills sperm
Plastic IUDs release progesterone and copper kill the sperm
Surgical methods
Sterilisation is cutting/tying Fallopian tube or sperm duct
Permanent procedure but small chance the tubes may rejoin
Natural methods
Find out when ovulating and avoid sex on those days
Popular with those who find the other methods unnatural
IVF process
FSH and LH given to woman to stimulate maturation of multiple eggs
Eggs collected from ovaries then fertilised in lab using sperm
Fertiliser eggs grow into embryos in a lab incubator
Once formed, one or two transferred to woman’s uterus
