2.89 Hormones

Understand the sources, roles and effects of the following hormones: ADH, adrenaline, insulin, testosterone, progesterone and oestrogen. 

Hormones are made in endocrine glands and are chemical messengers which travels in through blood in the plasma. (Because endocrine glands do not have ducts which carry hormones to target organs).

Adrenaline

Source: adrenal glands
Target: (many organs) e.g.) Heart

Excitement, anger, fright or stress 

Prep"Flight or fight" (attack or run for your life!)

Effects: 

- increased heart rate

- increased depth of breathing and breathing rate

- increased sweating

- hair standing on end (goose bumps)

- dilated (wider) pupils

- pallidness = blood is redirected to muscles

ADH - anti-diuretic hormones

Source: pituitary gland (in the brain)

Target: Collecting duct (of kidney tubules)

Controls amount of water to be reabsorbed into the blood in the kidney tubules (collecting duct) 

Insulin

Source: Pancreas

Target: Liver
Effect: Storage of glucose --> reduce blood sugar level 

Controls glucose level in the blood and keep it steady to prevent illness

Insulin is released after a meal (because glucose level rises after meal) to convert glucose into glycogen for storage and is insoluble. 


Glucagon
Source: Pancreas
Target: Liver
Effect: Break glycogen down into glucose in the liver 

Testosterone (male only)

Source: Testes
Target: (many organs) e.g.) Testis

For secondary growth and sexual characteristics in boys

Progesterone (female only)

Source: Ovaries

Target organ: Uterus Lining

Prevent the uterus lining from breaking down so that fertilized egg can plant into endometrium. (Maintain the lining of uterus.) If no sperm is present then ovaries stop producing progesterone and endometrium wall breaks down, resulting in menstrual bleeding.

Oestrogen (female only)

Source: Ovaries
Target: Uterus Lining
Effect: Buildup to the thickness of the uterus lining 

Responsible for secondary sexual characteristics 

Work with progesterone for menstrual cycle; Produce LH hormone that causes ovary to release its egg (ovulation) 


Difference between nerves and hormones:
- Hormones can have different effects