Hormonal coordination in humans

Question 1

Give the name of the body’s coordination

system which involves hormones

Answer 1

The endocrine system

Question 2

What is a hormone?

Answer 2

A hormone is a chemical messenger
secreted by a gland. It travels in the blood to
a target organ, where it causes a response.

Question 3

What type of organ secretes hormones?

Answer 3

Glands

Question 4

Which gland controls many other glands in the

body?

Answer 4

The pituitary gland

Question 5

Why is the pituitary gland considered a ‘master

gland’?

Answer 5

It secretes a wide range of hormones,
some of which may stimulate other
endocrine glands.

Question 6

What is the role of the pituitary gland in the endocrine

system?

Answer 6

● 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

Question 7

What is the role of the thyroid gland in the

endocrine system?

Answer 7

Secretes the hormone thyroxine - controls
metabolism, heart rate and body
temperature.

Question 8

What is the role of the pancreas in the endocrine

system?

Answer 8

Secretes the hormone insulin - controls

blood glucose levels.

Question 9

What is the role of the adrenal gland in the

endocrine system?

Answer 9

Secretes adrenaline - controls the body’s

‘fight or flight’ response

Question 10

What is the role of the ovaries in the endocrine

system?

Answer 10

Secrete oestrogen, which coordinates the
menstrual cycle and the development of
female secondary sexual characteristics.

Question 11

What is the role of the testes in the endocrine

system?

Answer 11

Secrete testosterone, which coordinates the
production of sperm and the development of
male secondary sexual characteristics.

Question 12

Which organ monitors and controls blood glucose

concentration?

Answer 12

The pancreas

Question 13

How does the pancreas respond when blood

glucose levels are too high?

Answer 13

The pancreas secretes the hormone
glucagon. Glucagon binds to liver cells,
causing glycogen to be converted into
glucose and released into the blood.

Question 14

How is blood glucose concentration controlled using

a negative feedback loop?

Answer 14

● 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.

Question 15

What is Type 1 diabetes?

Answer 15

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

Question 16

How can Type 1 diabetes be treated?

Answer 16

● 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.

Question 17

What is Type 2 diabetes?

Answer 17

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.

Question 18

How can Type 2 diabetes be treated?

Answer 18

● Following a carefully-controlled diet
● Doing regular exercise
● Losing weight
● Use of drugs which increase insulin
production and effectiveness

Question 19

What is osmosis?

Answer 19

Osmosis is the movement of water from a
dilute solution to a concentrated solution
through a partially permeable membrane.

Question 20

In what ways is water lost from the body?

Answer 20

● During exhalation via the lungs
● Sweating
● Urine (some reabsorbed in the kidney)

Question 21

In what ways are ions lost from the body?

Answer 21

● Sweating

● Urine (some reabsorbed in the kidney)

Question 22

How are excess amino acids excreted from the

body?

Answer 22

● 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.

Question 23

How do the kidneys maintain the balance of water

and other substances in the body? (

Answer 23

● Filter blood in order to remove waste
products eg. urea.
● Selectively reabsorb useful molecules eg.
glucose, water, ions

Question 24

What is the full name of the hormone ADH?

Answer 24

Anti-diuretic hormone

Question 25

Where is ADH secreted in the body?

Answer 25

The pituitary gland of the brain

Question 26

How does ADH affect the reabsorption of water in

the kidneys?

Answer 26

● 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.

Question 27

Why is kidney failure dangerous?

Answer 27

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.

Question 28

What are the two main ways of treating kidney

failure?

Answer 28

● Dialysis

● Transplant

Question 29

What is kidney dialysis?

Answer 29

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.