B.6.1 Outline the production and function of hormones in the body
- hormones are chemical messengers
- the hypothalamus controls the pituitary gland, which controls endocrine glands to produce hormones
- hormones are released into the bloodstream and picked up by specific receptors at remote locations (other sites around the body)
- hormones carry out a variety of functions and can be directed to specific cell types only due to receptor presence/absence
- negative feedback loops control action
- hormone synthesis + secretion --> effect --> the effect will limit/stop further hormone production
- e.g.) hormones include: ADH, aldosterone, estrogen, progesterone and testosterone, insulin, epinephrine (adrenaline), and thyroxine
B.6.2 Compare the structures of cholesterol and the sex hormones
- all have a common steroid background (17 carbons, 4 rings fused, 3 6C, 1 5C)
- the differences lie in the functional groups
- on Ring A: cholesterol and estradiol have -OH, while progesterone and testosterone have C=O
- on C17: cholesterol has a hydrocarbon, estradiol and testosterone have -OH, and progesterone has a C=O
B.6.3 Describe the mode of action of oral contraceptives
- an oral contraceptive is a pill that consists of estrogen and progesterone hormones (synthetic)
- an excess of these hormones from a certain dosage will prevent ovulation and thus pregnancy
- this is carried out through negative feedback inhibition
- an increased level of estrogen will inhibit the levels of luteinizing hormone (LH) released by the pituitary gland
- without enough LH and follicle stimulating hormone (FSH), the endometrium lining stops developing and the egg can't implant, thus stopping pregnancy
B.6.4 Outline the use and abuse of steroids
- testosterone promotes muscle growth in men
- it serves as an anabolic steroid (anabolic meaning to build up) to increase muscle mass
- for patients suffering from long illnesses such as cancer, testosterone-like steroids can help them regain muscle and body weight previously lost
- athletes sometimes abuse steroids to increase their own performance ability
- however, there can be negative side effects to taking large doses of steroids such as during steroid abuse, including increased signs of aging, impotence, balding, problems with urination, etc.