hormonal control 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 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 insulin. Insulin binds to receptors on the liver and muscles, causing excess glucose to be converted into glycogen and stored.

Question 14

how does the pancreas respond when blood glucose levels are too low?

Answer 14

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

Question 15

how is blood glucose concentration controlled using a negative feedback loop?

Answer 15

• when the blood glucose concentration rises or falls below the optimum, a hormone is secreted by the pancreas.
• the action of either hormone helps bring back the concentration to the correct level.

Question 16

what is type 1 diabetes?

Answer 16

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 17

how can type 1 diabetes be treated?

Answer 17

• 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 18

what is type 2 diabetes?

Answer 18

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 19

how can type 2 diabetes be treated?

Answer 19

• following a carefully-controlled diet
• doing regular exercise
• losing weight
• use of drugs which increase insulin production and effectiveness

Question 20

what is osmosis?

Answer 20

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

Question 21

in what ways is water lost from the body?

Answer 21

• during exhalation via the lungs
• sweating
• urine

Question 22

in what ways are ions lost from the body?

Answer 22

• sweating

- urine

Question 23

how are excess amino acids excreted from the body?

Answer 23

• 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 24

how do the kidneys maintain the balance of water and other substances in the body?

Answer 24

• filter blood in order to remove waste products eg. urea

- selectively reabsorb useful molecules eg. glucose, water, ions

Question 25

what is the full name of the hormone ADH?

Answer 25

Anti-diuretic hormone

Question 26

where is ADH secreted in the body?

Answer 26

the pituitary gland of the brain

Question 27

how does ADH affect the reabsorption of water in the kidneys?

Answer 27

• 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 kidneys tubules to water.
• more water is reabsorbed in the kidney, resulting in a smaller volume of more concentrated urine.

Question 28

why is kidney failure dangerous?

Answer 28

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 29

what are the 2 main ways of treating kidney failure?

Answer 29

• dialysis

- transplant

Question 30

what is kidney dialysis?

Answer 30

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.