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Where are hormones produced?
In glands
How are hormones transported around the body?
Through the bloodstream
What are the main glands in the endocrine system?
Pituitary glands, adrenal gland, pancreas, thyroid, ovaries and testes
What is adrenalin?
Produced by adrenal glands and prepares the body for fight or flight response
What are the effects of adrenalin on the body?
Increases heart rate, increases blood pressure, increases blood flow to muscles, raises blood sugar levels by stimulating the liver to change glycogen to glucose
What is thyroxine?
Produced in thyroid gland, controls metabolic rate, heart rate and temperature
What are the types of thyroxine and what are they used for?
TRH: thyrotropin releasing hormone, causes the release of TSH
TSH: thyrotropin stimulating hormone, produces thyroxine
What happens if thyroxine levels are too low?
It stimulates production of TRH in the hypothalamus, causing the release of TSH from pituitary glands. TSH causes the thyroid to produce thyroxine. When thyroxine levels are normal, TRH is inhibited and TSH is not produced
What are the stages of the menstrual cycle?
Days 1-4: if fertilisation doesn’t happen, the uterus lining is shed and the egg is kicked out - this is called menstruation
Days 4-13: uterus lining thickens and the ovary prepares for the release of an egg
Day 14: egg is released from ovaries - this is called ovulation
Days 15-28: uterus lining is maintained for potential implantation of a fertilised egg
What hormones are involved in the menstrual cycle?
FSH (follicle stimulating hormone), LH (lutenising hormone), progesterone and oestrogen
What is the role of FSH in the menstrual cycle?
Secreted by pituitary glands and transported to the ovaries through the blood, triggers development of follicle in ovaries and causing the release of oestrogen
What is the role of oestrogen in the menstrual cycle?
Secreted by ovaries, thickens uterus lining, inhibits FSH production and stimulates LH from the pituitary glands
What is the role of LH in the menstrual cycle?
Secreted by the pituitary gland and transported via the blood to the ovaries, triggers ovulation and stimulates the follicle remains to create the corpus luteum which secretes progesterone
What is the role of progesterone in the menstrual cycle?
Secreted by the corpus luteum in the ovaries, prepares uterus for implantation and inhibits FSH and LH. If there is no implantation, levels of progesterone decrease and the lining will be shed. FSH increases and the cycle starts again
What happened to progesterone levels if implantation of a fertilised egg happens?
The placenta continues progesterone production and prevent further ovulation and maintains the uterus lining
How does progesterone as a contraceptive influence the menstrual cycle?
It is difficult for sperm to enter due to thick cervical mucus and it thins the uterine lining, reducing the chance of implantation happening
How does oestrogen as a contraceptive influence the menstrual cycle?
Inhibits FSH to prevent ovulation
Advantages of hormonal contraception
It is 99% effective when used properly, is generally longer lasting than other methods and can be used to treat heavy periods
Risks of hormonal contraception
Has side effects such as bloating, doesn’t protect against STIs and may involve uncomfortable medical procedures
Advantages of barrier contraception
Simple and easy to use, prevents some STIs and there are no side effects
Risks of barrier contraception
Less effective than hormonal methods (the condom can split for example)
Explain the use of hormones in IVF
FSH and LH are given to the woman to stimulate ovulation, the egg is retrieved from the ovaries and fertilised in vitro, and the embryo is transferred to the woman’s uterus
What is homeostasis?
The maintenance of a stable core temperature
Why is homeostasis important?
To ensure that the optimum temperature is reached for enzymes and cellular processes to happen as quickly as possible
Why is homeostasis important to keeping body temperature controlled?
Enzymes work best at their optimum temperature, and deviations from this can decrease the rate of enzyme-controlled actions
What is thermoregulation?
The regulation of core body temperature
What is the role of the hypothalamus in thermoregulation?
Coordinates information from receptors and sends instructions to effectors
What are the responses of the body to an increase in temperature above 37 degrees?
Vasodilation (capillaries dilating), sweating, erector muscles relax and hairs lie flat
What is the role of the dermis in thermoregulation?
Contains sweat glands to control sweat production
What is the role of the epidermis in thermoregulation?
Contains pores which release sweat onto the skin
What is vasodilation?
The dilation of blood vessels near the surface of the skin, causing blood to flow closer to the skin’s surface and a greater heat loss to the surroundings
What are the responses of the body to a decrease in temperature below 37 degrees?
Vasoconstriction, shivering, hair muscles in erector muscles contract and there is a reduction in sweat production
How does shivering help increase the body temperature?
Contraction of muscles generates heat from respiration
What is vasoconstriction?
The constriction of blood vessels near the surface of the skin, so less blood flows towards the surface of the skin and less heat is lost to the surroundings
How does insulin control blood glucose concentration?
It causes liver and muscle cells to increase their uptake of glucose from blood and glucose is stored as glycogen
How does glucagon control blood glucose concentration?
It causes the breakdown of glycogen into glucose in the liver and glucose is released into the blood
What causes type 1 diabetes?
The pancreas naturally cannot produce enough insulin, passed down genetically
How is type 1 diabetes treated?
Daily insulin injections, limiting sugar intake and doing regular exercise
What causes type 2 diabetes?
The person develops insulin resistance or doesn’t produce enough insulin (usually because of obesity)
How is type 2 diabetes treated?
Balanced diet, exercise and insulin injections
Formula for BMI
BMI=mass/height²
What is the correlation between BMI and type 2 diabetes?
People with a BMI over 30 are more likely to develop type 2 diabetes as they can be classed as obese - they are positively correlated
What is osmoregulation?
Maintenance of constant water levels in the body fluids of an organism
Why is osmoregulation important?
It prevents cells bursting or shrinking when water enters or leaves by osmosis
What will happen to an animal cell if it is placed into a dilute solution?
Water molecules move down the concentration gradient into the cell by osmosis, so the pressure inside the cell increases until it bursts (lysis)
What will happen to an animal cell if it is placed into a concentrated solution?
Water moves down the concentration gradient out of the cell. The pressure in the cell decreases, causing it to shrivel up (crenation)
What are the functions of the kidneys?
Alters blood water levels, alters blood ion levels and removes toxic waste substances from the body
What is urine?
Waste product of the kidneys, containing urea, excess water and excess ions
How is urea produced?
Through the breakdown of excess amino acids
What are the structures in the urinary system?
Kidneys, renal vein, renal artery, ureter, urethra, bladded
What is the function of the renal artery?
To supply blood to the kidney
What is the function of the renal vein?
To drain blood from the kidney
What is the function of the ureter?
Takes urine from the kidneys to the bladder
What is the function of the urethra?
Releases urine from the bladder out of the body
What is a nephron?
A unit of the kidney where filtration and selective reabsorption takes place
What is filtration in the kidneys?
Blood flows through the glomerulus under high pressure, where small molecules and ions are filtered out of the blood and into the Bowman’s capsule of the nephron
Which substances are reabsorbed from the nephron tubule?
Sugars, some water and some ions
What happens to the molecules that aren’t reabsorbed?
They travel down the kidney tubule as urine and are transported to the bladder by the ureter, where they are stored and eventually excreted
What is ADH?
The hormone controlling concentration and volume of urine, produced by the pituitary gland
How does ADH affect the reabsorption of water from the kidney tubules?
It increases permeability of the collecting ducts, allowing more water to be absorbed
What happens when there is a low blood water concentration?
Receptors alert the hypothalamus, which stimulates the pituitary gland to release ADH, causing more water to be reabsorbed so the blood water content increases and more concentrated urine is produced
What happens when there is a high blood water concentration?
Receptors alert the hypothalamus, which stimulates the pituitary glands to secrete less ADH - less water is reabsorbed so the blood water content decreases and more dilute urine is produced
How can kidney failure be treated?
Using dialysis or a kidney transplant
What is kidney dialysis?
The machine which filters a patient’s blood
What does a kidney transplant involve?
Removing a kidney from a donor and implanting it into the patient
Risk of kidney transplants
There is a risk of rejection by the body
