Hormones

Question 1

Definition of Hormones

Answer 1

Hormones are chemical substances produced in minute quantities by endocrine glands and are transported by blood to specific target organs to exert its effect. They alter the activity of one or more specific target organ and is then destroyed in the liver and excreted in the kidneys.

Question 2

Endocrine glands

Answer 2

Endocrine glands are ductless glands (exocrine glands are glands with ducts attached e.g salivary gland/ gall bladder/ sweat gland)
Hormone produced is secreted directly into the bloodstream (in plasma) and then distributed around the body. Such glands have an extensive network of blood vessel to transport hormones to their target organs.

Question 3

Hypothalamus

Answer 3

Regulates the secretion of some pituitary hormones

Question 4

Pituitary glands

Answer 4

Secrete hormones that control other endocrine glands

Question 5

Adrenal Glands

Answer 5

Secrete adrenaline

Question 6

Ovaries

Answer 6

Secrete oestrogen and progesterone

Question 7

Testes

Answer 7

Secrete testosterone

Question 8

Pancreas

Answer 8

Contains a special group of cells called the Islet of Langerhans secrete Insulin and Glucagon into bloodstream.

Question 9

When is adrenaline secreted?

Answer 9

Adrenaline is secreted in response to stimuli that causes stress, anger, fear or anxiety. It allows the body to respond quickly to sudden demands for energy and its effects are usually short-lived.

Question 10

Where is adrenaline produced?

Answer 10

The adrenal medulla (in the adrenal glands which are positioned above the kidneys) secret adrenaline.
Secretion is controlled via the nervous system as the hypothalamus is activated by stimuli.

Question 11

Effects of adrenaline

Answer 11

Increase in blood glucose level by speeding the conversion of glycogen in the liver and muscles to glucose. Glucose is then transported to all vital organs especially heart and skeletal muscles. Increases heartbeat and blood pressure so that oxygen and glucose can be carried faster to the heart.

Question 12

Effects of adrenaline pt2.

Answer 12

Increases metabolic rate, allowing more energy to be released for tissue respiration.
Increase rate and depth of breathing
Contracts hair erector muscles producing ‘goose pimples’.
Constricts arterioles in skin causing paleness hence channeling more blood to muscles.
causes pupils to dilate to enhance vision.
Increases the rate of blood coagulation (in case of wounds, reduces rate of bleeding).

Question 13

Where is insulin and glucagon produced?

Answer 13

Pancreas contains a special group of cells called the Islet of Langerhans which secret insulin and glucagon in response to a change in blood glucose.

Question 14

How does the insulin help to decrease blood glucose level?

Answer 14

Stimulate the liver and muscle cells to convert excess glucose into glycogen for storage.
Increase permeability of cell membranes to glucose and hence increase the rate of glucose uptake by cells.
Increase the oxidation of glucose during tissue respiration.
*OVER SECRETION of insulin leads to abnormally low blood glucose concentration and symptoms include hunger rapid heartbeat and irritability. In severe cases, person may lapse into a coma or even die.
* LACK OF INSULIN abnormally high blood glucose concentration. Tissue Cells cannot utilise or store glucose. Symptoms include weak body, continual weight loss and glucose present in urine.

Question 15

Effects Of Glucagon

Answer 15

Released when blood glucose level becomes low. Glucagon increases the blood glucose concentration by stimulating the liver to…
Convert stored glycogen into glucose
Convert fats and amino acids into glucose
Convert lactic acid into glucose

Question 16

Diabetes Mellitus

Answer 16

Is a disease which is unable to regulate blood glucose level within normal range hence resulting in high blood glucose level.

Question 17

Type I

Answer 17

Early onset diabetes
Insufficient of no insulin production
Treatment: Insulin Injection

Question 18

Type II

Answer 18

Late onset diabetes (normally overweight people)
Insulin is produced but target cells do not respond well to insulin/ resistant to insulin.
Treatment: Control of dietary intake and exercising may need metaformin tablets and insulin injection

Question 19

Signs of diabetes mellitus

Answer 19

Persistent high blood glucose level
Presence of glucose in urine as the glucose level exceeds the kidneys ability to reabsorb all the glucose hence lost in urine.
Fatigue as less energy is released.
Hunger as body interprets inability to release energy as a sign of inadequate food.
Thirst as large amounts of glucose in blood draws water via osmosis.
Poor Vision as lens lose water and ability to focus is affected.
Slow healing of wounds, many untreated wound become gangrenous and needs to be amputated.