T5 hormonal coordination in humans Flashcards
name of the body’s coordination system which involves hormones
endocrine system
what is a hormone
chemical messenger secreted by a gland
travels in the blood to a target organ, where it causes a response
which gland controls many other glands in the body
pituitary gland
why is the pituitary gland considered a master gland
secretes a wide range of hormones, some of which may stimulate other endocrine glands
what is the role of the pituitary gland in the endocrine system
secretes HGH - controls human growth
stimulates the thyroid gland
stimulates ovulation and production of oestrogen in the ovaries
stimulates the production of sperm and testosterone in the testes
what is the role of the thyroid gland in the endocrine system
secretes thyroxine - controls metabolism, heart rate and body temperature
what is the role of the pancreas in the endocrine system
secretes insulin - controls blood glucose levels
what is the role of the adrenal gland in the endocrine system
secretes adrenaline - controls the body’s fight or flight response and is secreted during times of stress
role of the ovaries in the endocrine system
secretes oestrogen which coordinates the menstrual cycle and the development of female secondary sexual characteristics
role of the testes in the endocrine system
secrete testosterone which coordinates the production of sperm and the development of male secondary sexual characteristics
how does the pancreas respond when blood glucose levels are too high
pancreas secretes insulin
insulin binds to receptors on the liver and muscles, causing excess glucose to be converted into glycogen and stored
how does the pancreas respond when blood glucose levels are too low
pancreas secretes glucagon
glucagon binds to liver cells, causing glycogen to be converted into glucose and released into the blood
how is blood glucose concentration controlled using a negative feedback loop
when the conc rises or falls below the optimum, a hormone is secreted by the pancreas
action of either hormone helps bring back the conc to the correct level
what is type 1 diabetes
autoimmune disorder in which the pancreas doesn’t produce enough insulin to control the blood glucose conc
as a result, blood glucose levels are often very high, leading to excessive urination, tiredness and weight loss
how can type 1 diabetes be treated
insulin injections before meals - allows glucose to be converted into glycogen
limiting carbohydrate intake
attempts using pancreas and pancreatic cell transplants; investigations into genetic engineering of pancreatic cells
what is type 2 diabetes
disorder in which body’s cells stop responding to insulin, leading to an uncontrolled blood glucose conc
its onset is linked with increasing age and obesity
how can type 2 diabetes be treated
following a carefully-controlled diet
doing regular exercise
losing weight
use of drugs which increase insulin production and effectiveness
what is osmosis
movement of water from a dilute solution to a concentrated solution through a partially permeable membrane
in what ways is water lost from the body
during exhalation via the lungs
sweating
urine (some reabsorbed in the kidney)
in what ways are ions lost from the body
sweating
urine
how are excess amino acids excreted from the body
excess amino acids are deaminated in the liver to form ammonia
ammonia is toxic, therefore converted into urea
urea is excreted from the body via sweat and urine
how do kidneys maintain the balance of water and other substances in the body
filter blood in order to remove waste products
selectively reabsorb useful molecules
full name of ADH hormone
Anti-diuretic hormone
where is ADH secreted in the body
pituitary gland of the brain
how does ADH affect the reabsorption of water in the kidneys
when the blood is too concentrated, the pituitary gland secretes more ADH
ADH travels in the bloodstream to the kidney and increases the permeability of kidney tubules to water
more water is reabsorbed in the kidneys, resulting in a smaller volume of more concentrated urine
why is kidney failure dangerous
when damaged, unable to filter the blood properly
a build-up of toxic molecules in the body
uncontrolled ion and water balance and cells being damaged as a result of osmosis
two main ways of treating kidney failure
dialysis
transplant
what is kidney dialysis
use of a specialist machine to carry out the same function of kidneys
dialysis fluid contains the same concentration of glucose and ions as healthy blood
as a result, only excess and waste molecules are lost from the blood, and glucose and ions remain
function of reproductive hormones during puberty
M: cause the development of secondary sexual characteristics
F: cause the development of secondary sexual characteristics and maturation of eggs
main male reproductive hormone
testosterone, which is produced by the testes and controls sperm production
main female reproductive hormone
oestrogen, produced by ovaries and is involved in the menstrual cycle
what is the menstrual cycle
monthly cycle of physiological changes, involving the shedding of the uterus lining and ovulation
describe the events of the menstrual cycle
uterus lining thickens and eggs begin to mature in the ovaries
egg is released from one of the ovaries (ovulation) - uterus lining remains thick
if fertilised, pregnancy may occur
if not, both the egg and uterus lining are shed during menstruation
what is ovulation
release of a mature egg from the ovaries, which occurs approximately every 28 days
name the 4 main hormones involved in the menstrual cycle
oestrogen
progesterone
follicle stimulating hormone (FSH)
luteinising hormone (LH)
role of FSH in the menstrual cycle
secreted by pituitary gland
controls the maturation of eggs within the ovaries (inside a follicle) and triggers the production of oestrogen by the ovaries
role of oestrogen in the menstrual cycle
produced by the ovaries and released due to the action of FSH - it causes the regrowth of the uterus lining
triggers the production of LH and restricts the release of more FSH
role of LH in the menstrual cycle
produced in the pituitary gland as a result of oestrogen
release triggers ovulation
role of progesterone in the menstrual cycle
secreted from the follicle of the ovary
sustains the uterus lining and inhibits FSH and LH
two types of oral contraceptives
combined contraceptive pill (O and P)
mini pill (only progesterone)
how does the contraceptive pill prevent pregnancy
inhibits FSH - eggs don’t mature
prevents the development of the uterus lining - eggs can’t implant
increases the thickness of cervical mucus - immobilises sperm cells
what is the contraceptive patch
contains both O and P
patch placed on skin for 7 days at a time
what is the contraceptive implant
small rod inserted under the skin which releases progesterone - lasts for 3 years
what is the contraceptive injection
injection containing progesterone - lasts for 3 months
what is the IUS
intrauterine system - small plastic device that is inserted into the uterus
releases progesterone which thickens cervical mucus and prevents the build-up of the uterine lining
what is the IUD
intrauterine device - small copper-containing device inserted into the uterus which prevents the implantation of embryos
what is a spermicide
chemical that kills or immobilises sperm cells however not very effective and work better when combined with barrier methods
what is a barrier method of contraception
involves a physical separation between the sperm and egg
condoms - thin sheath worn on the penis or inside the vagina - protects against STIs but may tear/break
diaphragms - thin cap placed over the cervix, prevents entry of sperm
what surgical methods of contraception are available
sterilisation - in males, sperm ducts are tied (vasectomy) and in females, oviducts are tied
what is abstinence
practice of not having sex, which avoids pregnancy
some people abstain around the time of ovulation (rhythm method) but is quite unreliable
how do fertility drugs increase the chance of pregnancy
many contain FSH which stimulates O production and the maturation of eggs in the ovary
also contain LH which triggers ovulation
what is IVF
mother is given FSH and LH - stimulates maturation of eggs and ovulation
eggs are fertilised using sperm in lab - develop into embryos
1 or 2 are inserted into the mother’s womb
advantages of fertility treatment
allows infertile couples to have children
can store a woman’s eggs for later
disadvantages of fertility treatment
can be very expensive
low success rate
increases change of multiple pregnancies
side effects - mental & physical
what is negative feedback
type of control where the body responds to an increase or decrease in a factor by returning it to the optimum level
what is thyroxine
hormone released by thyroid gland
release is triggered by the thyroid stimulating hormone (TSH)
controls the body’s metabolic rate, growth and development
how is the release of thyroxine controlled by negative feedback
levels of blood thyroxine falls - detected by receptors in the brain
pituitary gland releases more TSH
more thyroxine produced and released by the thyroid gland
blood thyroxine level returns to normal
what are the effects of adrenaline
increase in H&BR - delivers oxygen and glucose to the body
stored glycogen converted to glucose
dilation of pupils
increased mental awareness
blood diverted away from digestive system to muscles
