kidneys + reproduction system

How do we lose water and why is water regulation so important?

• l: sweat, lungs when we breathe, urine

• w: cells will lose/gain water through osmosis, too much - cells swell, burst, too little - shrink

How do the kidneys work?

• as blood passes through, kidney tubules absorb anything small e.g water, glucose, amino acids, urea

• tubules don’t absorb large molecules e.g cells, proteins

• the body then selectively reabsorbs what it needs - does not reabsorb urea

What happens when water levels are too low/high?

l: hypothalamus signals to the pituitary gland to release anti-diuretic hormone, adh reaches the kidneys and encourages reabsorption of water - less urine, more concentrated

h: hypothalamus stops sending signals to pituitary gland, won’t release as much adh, less travelling to kidneys and so less reabsorption of water - more urine, less concentrated

Role of the kidneys

• remove waste products e.g urea from blood

• regulate level of ions in blood

• regulate level of water in blood

How does the urinary system work? (4)

• blood into kidneys through renal arteries, blood out through renal veins

• kidneys produce urine

• passes down ureters, stored in the bladder

• urinated out through urethra

Consequences of kidney failure (4)

• waste substances build up in bloodstream

• unable to regulate water and ion levels

• ill and could die if untreated

Treatment for kidney failure (2)

• dialysis

• kidney transplant

What happens in dialysis (6)

• blood enters machine

• dialysis fluid is made up of the same conc. of water and other molecules as in healthy blood

• passes through dialysis fluid, separated by a partially permeable membrane

• small molecules can diffuse, big cannot

• if the patient has too much of something in their blood, it will diffuse into the dialysis fluid

• to prevent it reaching equilibrium, the dialysis fluid is constantly replaced

Problems with dialysis (5)

• process is time consuming

• will have to have it for the rest of their life

• can cause blood clots

• can cause infections

• expensive

Problems with kidney failure (3)

• something could wrong with the surgery

• organ might be rejected (attacked by patients own immune system)

• not enough donors to give everyone a transplant

Describe stage 2 of the menstrual cycle (after bleeding before ovulation) (4)

• uterus lining starts to build up again

• lining becomes a thick spongy layer with lots of blood vessels

• lasts around 10 days (up to ovulation)

• prepare the lining for a fertilised egg

Describe stage 4 of the menstrual cycle (after ovulation) (3)

• aims to maintain the uterus lining

• at the end of the cycle if there is no fertilised egg, the uterus lining starts breaking down again (back to stage 1)

• if there is, it will implant into uterus lining and slowly develop into a fetus

Oestrogen and how it controls the menstrual cycle (4)

• produced in the ovaries

• stimulates uterus lining to grow

• increases as uterus lining develops

• decreases after ovulation

Progesterone and how it controls the menstrual cycle (4)

• produced in the ovaries

• increases after ovulation

• maintains the uterus lining

• if levels drop, the lining breaks down and the cycle repeats

LH and how it controls the menstrual cycle (2)

• produced in the pituitary gland

• stimulates release of the egg on day 14

FSH and how it controls the menstrual cycle (2)

• produced in the pituitary gland

• causes an egg to mature in one of the ovaries

Describe the menstrual cycle using the hormones

• high fsh stimulates ovaries to produce oestrogen

• oestrogen inhibits fsh

• oestrogen stimulates lh

• progesterone increases and inhibits fsh + lh

Hormonal methods of contraception + how they work (4)

• oestrogen - inhibits fsh, no egg developed nor released

• progesterone - stimulates production production of thick mucus in the cervix so sperm cannot reach the egg

• the pill - combination of oestrogen and progesterone can have side effects e.g nausea, headaches

• patch - 1 week, injection - 2-3 months, implant - 3 years, plastic iud - over 3 years

Non-hormonal methods of contraception (4)

• male and female condoms

• diaphragm (shallow cup placed over cervix), not reliable so has to be used with spermicide which can also be used alone

• sterilisation - cutting or tying fallopian tubes or sperm ducts

• only having sex at infertile periods or stopping before ejaculation

How does IVF work?

• woman is given fsh and lh to stimulate eggs to mature

• eggs are collected from ovaries

• eggs fertilized by sperm outside of the body

• eggs placed in an incubator and left to grow into embryos

• embryo(s) inserted into mothers uterus and hopefully grows into a fetus

Pros and cons of IVF

• p: allows infertile couples to have children

• c: doesn’t always work, stressful, abdominal pain, nausea, multiple embryos inserted which is high risk, unused embryos are destroyed