Hormonal coordination in humans Flashcards
Give the name of the body’s coordination
system which involves hormones
The endocrine system
What is a hormone?
A hormone is a chemical messenger
secreted by a gland. It travels in the blood to
a target organ, where it causes a response.
What type of organ secretes hormones?
Glands
Which gland controls many other glands in the
body?
The pituitary gland
Why is the pituitary gland considered a ‘master
gland’?
It 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 human growth hormone - controls human
growth.
● Stimulates the thyroid gland.
● Stimulates ovulation and the 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 the hormone thyroxine - controls
metabolism, heart rate and body
temperature.
What is the role of the pancreas in the endocrine
system?
Secretes the hormone 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
What is the role of the ovaries in the endocrine
system?
Secrete oestrogen, which coordinates the
menstrual cycle and the development of
female secondary sexual characteristics.
What is the role of the testes in the endocrine
system?
Secrete testosterone, which coordinates the
production of sperm and the development of
male secondary sexual characteristics.
Which organ monitors and controls blood glucose
concentration?
The pancreas
How does the pancreas respond when blood
glucose levels are too high?
The pancreas secretes the hormone
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 blood glucose concentration rises or falls
below the optimum, a hormone is secreted by the
pancreas.
● The action of either hormone (insulin or glucagon)
helps bring back the concentration to the correct
level.
What is Type 1 diabetes?
Type 1 diabetes is an autoimmune disorder in
which the pancreas does not produce sufficient
insulin to control the blood glucose concentration.
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?
Type 2 diabetes is a disorder in which the body’s cells stop responding to insulin, leading to an uncontrolled blood glucose concentration. 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?
Osmosis is the 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 (some reabsorbed in the kidney)
How are excess amino acids excreted from the
body?
● Excess amino acids are deaminated in the liver to
form ammonia.
● Ammonia is toxic, therefore it is converted into urea
● Urea is excreted from the body via sweat and urine.
How do the kidneys maintain the balance of water
and other substances in the body? (
● Filter blood in order to remove waste
products eg. urea.
● Selectively reabsorb useful molecules eg.
glucose, water, ions
What is the full name of the hormone ADH?
Anti-diuretic hormone
Where is ADH secreted in the body?
The 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 the kidneys are damaged, they may be unable
to filter the blood properly. This may lead to:
● A build-up of toxic molecules (eg. urea) in the
body.
● An uncontrolled ion and water balance and cells
being damaged as a result of osmosis.
What are the two main ways of treating kidney
failure?
● Dialysis
● Transplant
What is kidney dialysis?
Kidney dialysis is the use of a specialist machine
to carry out the 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.
