Hormones that Affect Blood Sugar

Pancreatic Hormones Produced in the islets of Langerhans. –Beta (β) cells produce insulin. –Alpha (α) cells produce glucagon.

Hormonal Response to High Blood Sugar ↑ blood sugar = release of insulin. Causes muscle, liver and other body cells to become permeable to glucose. Glucose stored as glycogen. Result = ↓ blood sugar.

Hormonal Response to Low Blood Sugar ↓ blood sugar = release of glucagon. Promotes breakdown of glycogen into glucose, which is released into the blood. Result = ↑ blood sugar.

Adrenal Glands Each composed of two glands. 1.Adrenal medulla  short-term stress. 2.Adrenal cortex  long-term stress.

Adrenal Medulla Produces epinephrine (adrenaline) and norepinephrine (noradrenaline). “Fight-or Flight Response”. –↑ blood sugar (glycogen  glucose). –↑ HR, breathing rate & cell metabolism. –Dilation of blood vessels. –Pupil dilation.

Adrenal Cortex Produces 3 types of hormones: –Glucocorticoids. –Mineralcorticoids. –Sex hormones.

Adrenal Cortex Glucocorticoids (e.g., cortisol): –Promotes conversion of amino acids to glucose –Promotes breakdown of fats to fatty acids –Decreased glucose uptake by muscles –Increased blood sugar in response to stress

Fight or Flight and Blood Sugar Why block insulin during fight-or-flight response?

Hormones that Affect Metabolism

Two Major Glands Thyroid Gland Parathyroid Gland

Thyroid Gland Thyroxine (T4) Triiodothyronine (T3) –Both need iodine to be produced. –Used to oxidize sugar and other nutrients. –More T4 in the blood will “boost metabolism”

Hypothyroid or Hyperthyroid If the thyroid gland produces T4 and T3, hormones that regulate metabolism, what would happen if: a)The thyroid stopped producing T4 and T3? (hypothyroidism) b)The thyroid could not stop producing T4 and T3? (hyperthyroidism)

Acronyms: TRH – Thyroid Releasing Hormone TSH – Thyroid Stimulating Hormone

Parathyroid Glands Four groups of cells on the thyroid gland. Release a hormone called parathyroid hormone, or “PTH”. –PTH raises the calcium levels in the blood.

Negative Feedback

Calcitonin Calcitonin is also released by the thyroid, and it counter-acts parathyroid hormone (PTH) by: Inhibiting Ca 2+ absorption by the intestines Inhibits Ca 2+ reabsorption in the nephrons of the kidney

Human Growth Hormone (HGH) Too much? - Giantism Too little? - Dwarfism Produced in and released from the anterior pituitary gland. Andre the giant 7 ft 4 inches 520 lb.

Human Growth Hormone Cause cells to grow in size and in number. Promotes protein synthesis. Promotes the breakdown of fats. –↑ GH, muscles use fatty acids as energy –Loss of fat during growth spurts