Bio 257 Day 24 Today’s topics  Thyroid Gland  Parathyroid Glands  Thymus  Adrenal Glands  Pancreas  Gonads

Thyroid Gland Homones- thyroxine-T 4 & triiodothyronine-T 3 – increases basal metabolic rate need for growth & maturation –Target: most organs

Thyroid Gland Hormone-calcitonin – decreases blood calcium levels by decreasing bone breakdown –Target: bone (inhibit osteoclasts), kidneys

Parathyroid Gland 4 pea –sized lobes embedded in the posterior portion of thyroid gland 1 hormone = PTH (parathyroid hormone) – increases blood calcium levels –Target: bone, kidneys

Trachea Thymus Lung Heart Ribs Relative Location of Thymus

Thymus Gland Anterior & superior to heart Decreases in size with age 1 hormone = thymosin – stimulates t-cell (WBC, lymphocyte) development & maturation –Target: Immune tissue - t-cells, bone marrow, lymphatic tissue, thymus

diaphragm left adrenal gland left kidney ureter urinary bladder Adrenal Glands Posterior view

Adrenal Glands Sit atop of each kidney Consist of two major tissue layers –Adrenal cortex = outer portion –Adrenal medulla = inner portion

Adrenal Glands Adrenal Medulla –2 major hormones = epinephrine & to a small extent norepinephrine Same effects as sympathetic division of the nervous system

Regulation of Adrenal Medullary Secretions

Adrenal Glands Adrenal cortex –3 major classes of hormones 1) Glucocorticoids 2) Mineralocorticoids 3) Androgens

Adrenal Glands Adrenal cortex –Glucocorticoid Hormones mainly Cortisol increases the synthesis of glucose from proteins & fats to increase glucose reserve and antinflammatory effects target many organs

Adrenal Glands Adrenal cortex – Mineralocorticoid Hormones mainly Aldosterone regulates Na+ & K+ blood levels by increasing Na+ & decreasing K+ target: primarily kidneys, small extent intestines and sweat glands

Regulation of Aldosterone Secretion

Adrenal Glands Adrenal cortex – Androgens male sex hormones in females stimulate pubic & axillary hair grow and sex drive, in males negligible effects over secretion in females results in masculinization

Structure of Pancreas

Regulation of Blood Glucose Levels

Pancreas Gland Lies behind the stomach and 1 st portion of small intestines (duodenum) Contains clusters of endocrine cells called Islets of Langerhans

Pancreas Gland 2 primary hormones = glucagon and insulin Insulin (Beta-cells) –Lowers blood glucose levels by increasing the uptake of blood glucose by liver & muscles –Targets: primarily liver and skeletal muscles

Pancreas Gland Glucagon (alpha-cells) –Increases blood glucose levels by increasing the breakdown of glycogen by liver –Target: Primarily liver

 Ovaries, located in the pelvic cavity of the female.  remain functionless,until puberty, when secretion of FSH & LH stimulates them. Gonads Gonads (ovaries & testes)

progesterone & estrogen  stimulates uterinelining growth for menstrual cycle or pregnancy development  stimulates uterine lining growth for menstrual cycle or pregnancy development  development of ovaries, & female secondary sex characteristics. Ovarian Hormones

Testes (male)  suspended in a sac called the scrotum, outside the male pelvic cavity  produce hormones called androgens -testosterone is the most important.

 stimulates growth & maturation of male reproductive organs  development of male secondary sex characteristics  aids in production of sperm  stimulation of the male sex drive Testosterone