Chapter 15 - Hormones

Question 1

Define hormones.

Answer 1

Hormones are chemical substances produced in minute quantities by endocrine glands. They are secreted directly into the bloodstream and transported by blood, affecting one or more specific target organs. After performing their functions, they are destroyed in the liver and excreted by the kidneys.

Question 2

What happens when the production of thyroid hormones are not carefully controlled?

Answer 2

Too little thyroid hormones might cause children to be mentally and physically retarded, and adults to be mentally and physically sluggish.
Too much thyroid hormones results in increased metabolic rate, high breathing rate and high body temperature, which might lead to heart failure if not treated.

Question 3

How is the production of hormones controlled?(2)

Answer 3

1) the nervous system

2) certain chemical substances

Question 4

What is the function of hormones?

Answer 4

Hormones influence the growth, development, and activity of an organism.

Question 5

What are the two types of glands? List 3 examples for each type.

Answer 5

1) endocrine glands (adrenal glands, pituitary glands, Islet of Langerhans in pancreas)
2) exocrine glands (sweat glands, salivary glands, pancreas)

Question 6

What are endocrine glands?

Answer 6

Ductless glands that transport their secretions via bloodstream directly.

Question 7

What are exocrine glands?

Answer 7

It contains ducts to transport secretion to target organs.

Question 8

What is the function of the pituitary gland?

Answer 8

It secretes a number of hormones which control the secretion of hormones of several other endocrine glands.

Question 9

What hormones does the pituitary gland secrete?(3)

Answer 9

1) growth hormone
2) antidiuretic hormone
3) thyroid-stimulating hormone

Question 10

What is a hypothalamus?

Answer 10

It is an endocrine gland that regulates the secretion of some pituitary hormones.

Question 11

Where is the adrenal gland and what is its function?

Answer 11

It is situated on top each kidney and releases adrenaline when stimulated by the nervous system.

Question 12

What are the functions of 2 glands of the liver?

Answer 12

1) exocrine gland secretes pancreatic juices via pancreatic ducts
2) endocrine - islet of langerhans secrete insulin and glucagon to control blood glucose levels

Question 13

What 2 hormones does the gonad (ovaries) in females secrete and what are their functions?

Answer 13

1) oestrogen - controls development of breasts and broadening of pelvis
2) progesterone - helps maintain healthy pregnancy

Question 14

What hormone does the gonad (testis) in male secrete and what is its function?

Answer 14

Testes secrete testosterone which causes the deepening of voice and growth of facial hair.

Question 15

What are the 3 effects of normal amount of insulin secreted?

Answer 15

Insulin decreases blood glucose concentration by:

1) increasing the permeability of cell membranes to glucose, thus increasing rate of glucose uptake by cells
2) stimulating the liver and muscle cells to convert excess glucose into glycogen for storage (glycogenesis)
3) increasing oxidation of glucose during tissue respiration

Question 16

What are the 4 effects of too little amount of insulin secreted?

Answer 16

1) glucose cannot be stored or utilized by tissue cells, increasing the blood glucose concentration.
2) body grows weak and continuously loses weight as muscle cells have no reserves of glycogen
3) body oxidizes fats instead of glucose to produce energy, resulting in poisonous ketones to be excreted in the urine
4) some glucose are lost in urine, giving rise to diabetes mellitus

Question 17

What are 3 effects of oversecretion of insulin?

Answer 17

1) abnormal decrease in blood glucose concentration, resulting in hunger, rapid heartbeat, irritability
2) results in a condition called shock.
3) might lead to coma or death

Question 18

What is diabetes mellitus?

Answer 18

It is a disease where the body is unable to control its blood glucose concentration so that it remains within normal limits.

Question 19

What are 3 symptoms of diabetes mellitus?

Answer 19

1) constantly high blood glucose concentration
2) presence of glucose in urine after meal
3) healing of wounds is slow and difficult

Question 20

What are the 3 differences between Type I and Type II diabetes?

Answer 20

1) type I develops early in life while type II develops late in life.
2) type I diabetes is caused by insufficient or no insulin production, while in type II diabetes, insulin is produced by target cells do not respond well (insulin resistance)
3) type I can be treated by insulin injection and maintaining a supply of sugary foods while type II can be treated by control of dietary intake and exercising.

Question 21

How does glucagon increase blood glucose concentrations?

Answer 21

It stimulates the conversions of

1) glycogen into glucose (glycolysis)
2) fats and amino acids into glucose
3) lactic acid into glucose

Question 22

What is the function of adrenaline?

Answer 22

It is secretes in response to stress or excitement, allowing the body to respond quickly to sudden demands for energy. The effects are usually short-lived.

Question 23

How is adrenaline being secreted? (5)

Answer 23

1) stimulus activate hypothalamus in brain
2) nerve impulses transmit down the spinal cord
3) motor neurone transmits impulses to adrenal gland
4) adrenal gland secretes adrenaline into bloodstream
5) blood transports adrenaline to target organs via bloodstream

Question 24

What are 9 effects of adrenaline secretion?

Answer 24

1) stimulates liver to convert glycogen to glucose so more glucose is available to release energy for muscle contraction. increases blood glucose level
2) increases metabolic rate, allowing more energy to be released in tissue respiration through increased levels of glucose for fight or flight response.
3) increases rate of heartbeat, causing a rise to blood pressure so that oxygen and glucose can be carried faster to muscles
4) increases rate and depth of ventilation, increasing rate of uptake of oxygen by lungs
5) increases rate of blood clotting
6) constrict arterioles in gut, decreasing digestive activities
7) constrict arterioles in skin, causing paleness, channeling more blood to muscles
8) pupils dilate to enhance vision
9) contract hair muscles, producing “goose bumps”

Question 25

What are 3 similarities between endocrine and nervous controls?

Answer 25

Both have the components:

1) receptor that detects stimuli
2) signal or message that is transmitted
3) effector (target organ that carries out response)

Question 26

How does nervous coordination and hormonal coordination differ? (4)

Answer 26

1) nervous coordination is faster than hormonal coordination
2) nervous coordination involves transmission of electrical impulses while hormonal coordination involves the transmission of chemical substances
3) nervous coordination produces short-term responses, while hormonal coordination can produce short term or long term responses
4) nervous coordination is usually localised, while hormonal coordination may affect more than one target organs.