Endocrine System

The Endocrine System is responsible for controlling the body by producing and releasing hormones that regulate long-term metabolic activity.

maintain homeostasis in the blood

growth and development

regulate cellular metabolism and energy balance

reproduction and sexual development

Glands and Hormones

Endocrine glands release hormones directly into the bloodstream for chemical signaling of Target Cells. Hormones are chemical messengers made of amino acids or steroids that alter cellular activity - increase or decrease the rate of metabolic processes.

Hormone Feedback and Regulation

Negative Feedback: inhibitory (slow down) and stabilizing and adjusts to maintain homeostasis has opposing hormones

Positive Feedback: stimulation (speed up) and stabilizing and amplifies the effect of stimuli

Glands are activated by different stimuli.

Neural: nerve fibers stimulate hormone release - sympathetic nervous system stimulates the adrenal medulla to release epinephrine and norepinephrine.

Humoral: changing blood levels stimulates hormone release - release of PTH (Parathyroid) prompted by decrease of Ca² levels.

Hormonal: hormones stimulate other organs - hypothalamic hormones stimulate the anterior pituitary gland.

Pituitary Gland: “master gland” - controls and regulates other glands

G.O.A.T F.L.A.P

Anterior-

Growth (GH) - total body growth

Prolactin (PRL) - stimulates production of breast milk

Adrenocorticotrophic (ACTH) - stimulates adrenal cortex ~ release hormones

Thyroid-stimulating (TSH) - stimultaes thyroid gland ~ release hormones

Follicle-stimulating (FSH) - stimulates ovaries/testes ~ release hormones or produce gamates

Luteinizing (LH) - stimulates ovaries/testes ~ release hormones or produce gamates

Posterior-

Oxytocin - stimulates uterine contractions and milk ejection

Antidiuretic (ADH) - stimulates kidney to reabsorb water - prevents urine formation. Urine volume decreases, blood volume inceases and bp increases

Thyroid Gland: base of the throat

Thyroxine (T3) & Triiodothyronine (T4) - stimulates body metabolism ~ regulates energy production and body heat, blood pressure, tissue growth, stimulated by TSH

Calcitonin - lowers blood Ca levels (from high blood Ca) by removing Ca from blood and depositing in bone, targets osteoblasts

Parathyroid Gland: 4 tiny masses of glandular tissue, posterior surface of thyroid

Parathyroid (PTH) - increases blood Ca levels (from low blood Ca) by removing Ca from bone and depositong into blood, targets osteoclasts to break down bones

Adrenal Glands: above each kidney, outer region (adrenal cortex), inner region (adrenal medulla)

Adrenal Cortex-

Mineralocorticoids - regulate Na+/K+ reabsorption in kidneys ~ regulate blood volume, and blood pressure

Glucocorticoids - allows body to withstand long-term stress, releasing glucose into blood, decrease inflammatory response ~ stimulated by ACTH

Gonadocorticoids - small amounts of estrogen or testosterone (androgens) - contributes to onset of puberty

Adrenal Medulla-

Catecholamines - activates sympatheic ANS, increase fight or flight response

Pancreas: close to the stomach, abdominal cavity, mixed gland

Insulin - high blood sugar level ~ stimulates glucose uptake from blood into cells to be oxidized for energy, converted into glycogen or fat, released by beta cells

Glucagon - low blood sugar level ~ stimulates liver to release sugars stolen in glycogen, targets liver, glucagon is released by alpha cells

Gonads: ovaries and testes - stimulated by FSH and LH

Estrogen - maturation of reproductive organs, 2nd sex characteristics

Progesterone (Ovaries) - works with estrogen for breast development, menstrual cycle

Testosterone (Testes) - promotes the development of male reproductive organs, 2nd sex characteristics, necessary for sperm production

Thymus Gland: active in childhood and atrophies as we age

Thymosin - maturation of T cells (lymphocytes) ~ important in immunity

Pineal Gland: roof of the 3rd ventricle of the brain

Melatonin - affects biological rhythms and reproductive behaviors

Extra Credit -

Exophthalmos: eyes are protruding (poking out)

Tetany: tingling noted around mouth and feet

Diaphoretic: sweating

Polydipsia: extreme thirst

Hypernatremia: the level of sodium is too high

Hypokalemia: the amount of potassium in the blood is too low

Hyperglycemia: high blood glucose

Glucosuria: urine contains sugars (glucose, lactose, fructose, or galactose)