Homeostasis And Response (part 2) Flashcards
Glucose changes
Comes from eating foods high in carbohydrates
Normal metabolism of cells removes glucose
Vigorous exercise removes much more
Glucose monitoring
Stored as glycogen in liver
Insulin is secreted by pancreas when too high, moves glucose from blood into liver and muscles to be stored as glycogen
Too low- pancreas secretes glucagon, liver releases glucose that glucagon has made from glycogen
Diabetes types
Type 1- pancreas produces little or no insulin, blood glucose can rise to a level which kills them
Type 2- people become resistant to their own insulin so it can’t store glucose
Type 1 treatment
Have insulin injected, particularly at mealtimes to store glucose. Amount based on diet and exercise. Need to think about how many simple carbohydrates and do more exercise
Type 2- carbohydrate-controlled diet, regular exercise
Kidneys
Filter waste products out of the blood- filtration
Then reabsorbs useful substances like glucose, some ions and the right amount of water, called selective reabsorption.
Urea
Proteins and amino acids can’t be stored, excess to fats and carbohydrates, in the liver- deamination
Ammonia is a waste prided
Toxic so converted to urea in liver- transported to kidneys, filtered out, leaves in urine
Ions
Taken in via food
If concentrations are wrong, the amount of water absorbed via osmosis is wrong
Some lost in sweat but not regulated so kidneys reabsorb the right amount
Water
Must balance water in and out
Lose in sweat and lungs when breathing out
We can’t control these ways so the kidneys control the amount lost in urine
Water control
Anti-diuretic hormone (ADH) controls- released by pituitary gland
Brain monitors and makes pituitary gland release ADH accordingly
Negative feedback loop
Kidney failure
Will lead to death as you can’t control ion and water concentration
Treated by dialysis machines or transplant
Dialysis machines
Done regularly to keep blood concentrations at normal levels
Blood flows between partially permeable membranes with dialysis fluid around
Dialysis fluid has same concentrations as healthy blood
Useful won’t be lost
Waste substances diffuse across
Dialysis session 3 times a week, 3-4 hours, not fun, expensive
Kidney transplants
The only cure is a transplant
Normally from those who have died suddenly
Transplanted from one to be on the donor register, donor card
Can be done from those who are alive, small risk
Could be rejected despite drugs to prevent this
Transplants are cheaper, long waiting list
Puberty
Hormones trigger off secondary sexual characteristics e.g. men facial/body hair, voice deepening, women breasts
Men- testosterone, produced by testes ( and less by ovaries) and stimulates sperm production
Women- oestrogen, ovaries, physical changes and menstrual cycle
Menstrual cycle stages
Stage 1- menstruation, uterus lining breaks down for 4 days
Stage 2- builds up again, days 4-14, thick spongy layer of blood vessels, fertilised egg
Stage 3- egg develops released at day 14- ovulation
Stage 4- wall is maintained for 14 days, no fertilised egg by day 28 then is breaks down and starts again
FSH
Follicle- Stimulating Hormone
Produced in the pituitary gland
Causes an egg to mature in a follicle in the ovaries
Stimulates oestrogen
Oestrogen
Produced in the ovaries
Causes uterus lining to grow
Stimulates LH, inhibits FSH
LH
Luteinising hormone
Produced by the pituitary gland
Stimulates the release of an egg at day 14 (ovulation)
Progesterone
Produced in the ovaries by the remains of follicle after ovulation
Maintains lining of the uterus during the second half, breaks down as level decreases
Inhibits LH and FSH
Hormones to reduce fertility
Daily Oestrogen prevents the release of an egg, permanently high so there it inhibits FSH
Progesterone stimulates production of thick mucus that stops sperm reaching egg
Pill
Combined oral contraceptive- oestrogen and progesterone, over 99% successful, causes headaches and nausea
Doesn’t protect against STIs
Progesterone-only, fewer side effects, just as effective
Other contraceptive methods with hormones
5x5 cm patch, lasts a week, same as the pill
Implant under the arm, continuous progesterone, stops ovaries releasing eggs, can last 3 years
Contraceptive injection, progesterone 2-3 months
Intrauterine device (IUD), t-shaped device in uterus, kills sperm, prevents implantation. Plastic IUDs release progesterone and copper IUDs
Barriers
Condoms on penis/ in vagina, stop sperm reaching and STIs
Diaphragm over cervix, used with spermicides
Spermicide alone, less effective (70-80%)
Drastic methods
Sterilisation- cutting or tying Fallopian tubes or sperm duct, permanent in men, small chance of rejoining
Natural- finding out when in the menstrual cycle is most fertile and avoiding intercourse then, not very effective
Abstinence- only 100% effective, no sexual intercourse
FSH and LH increasing fertility
Given to ensure levels are high enough for ovulation
- doesn’t always work
- too many could be stimulated
IVF
In vitro fertilisation
Collecting eggs from ovaries, fertilise in lab with sperm
ICSI (intra-cytoplasmic sperm injection) ICSI, injected directly into egg
Grow into embryos in incubator, 1/2 implanted when balls of cells
Given before egg collection
IVF pros/cons
+ gives a child
- multiple births
- 26% success rate, lots of failures
- emotional stress
- physical stress (abdo pain, vomiting, dehydration)
Microscope techniques
Micro-tools used
Remove cells from embryo for testing
Time-lapse imaging means it can be monitored
Issues with IVF
Unused embryos destroyed, unethical as each is a potential life
Genetic testing could lead to preferred characteristics, some see as unethical
Adrenaline
Released by the adrenal glands- just above kidneys
Released for stressful or scary situations, detects fear or stress, impulses to adrenal glands
“Fight or flight” as it increases oxygen and glucose supply to brain and muscles
Thyroxine
Released by thyroid gland
Regulates basal metabolic rate, protein synthesis
Released in response to thyroid stimulating hormones (TSH)
Negative feedback, when thyroxine is too high, TSH is inhibited and restarted when it goes too low
