Hormones

Hormone Overview Hormones Chemicals released from one organ that can control the physiology of other organ(s) in the body similar to the nervous system except hormones: respond slower have a longer duration of action potentially can affect every cell in the body two types of hormones fat soluble – usually derived from cholesterol binds to receptors in the cell water soluble binds to receptors on cell membrane

Hormone Mediation endocrine cell target organ blood vessel

Hormone Regulation Hormone release by endocrine glands is usually controlled by the hypothalamus and pituitary gland pituitary gland receives input from the hypothalamus or other hormones hypothalamus contains sensory areas that can respond to body physiology, hormonal signals, and neural information from the brain

Pituitary Gland Divided into two parts Anterior 4 hormones control release of other hormones adrenocorticotropic hormone thyroid stimulating hormone follicle stimulating hormone luteinizing hormone 2 hormones act directly (human) growth hormone prolactin Posterior two hormones which act directly antidiuretic hormone oxytocin

Pituitary Gland Hypothalamic Control Anterior Pituitary hypothalamus secretes releasing hormones locally which are then carried to the anterior pituitary Posterior Pituitary hypothalamic neurons manufacture the hormones which are then transported down the axons to the posterior pituitary

Pituitary Gland

Anterior more cellular due to amount of hormones manufactured pars distalis pars intermedia secrets MSH Posterior mostly acellular, contains primarily axons from hypothalamus

Pituitary Gland anterior pituitary Anterior more cellular due to amount of hormones manufactured Posterior mostly acellular, contains primarily axons from hypothalamus

Pituitary Gland posterior pituitary Anterior more cellular due to amount of hormones manufactured Posterior mostly acellular, contains primarily axons from hypothalamus

Anterior Pituitary Hormones hormone nameabbreviationmajor effects growth hormonehGH stimulates growth of bones, cartilage, muscle timing and amount released determines body size prolactinPRL stimulates breast development promotes and maintains lactation after childbirth adrenocorticotropic hormone ACTH regulates the activity of the cortex of the adrenal gland thyroid stimulating hormone TSH stimulates production and release of thyroid hormone follicle stimulating hormone FSH causes formation of ovarian follicles and stimulates them to produce estrogen stimulates sperm development in men lutienizing hormoneLH initiates ovulation, maintains corpus luteum regulates testosterone production in males

Posterior Pituitary Hormones hormone nameabbreviationmajor effects antidiuretic hormoneADH reduces urine output by increasing water reabsorption in the kidney plays small role in blood pressure regulation oxytocinOT causes uterine contractions in labor causes milk ejection in lactating mothers

Thyroid Bilobed located just under the cricoid cartilage

Thyroid Follicles produces and stores thyroid hormone follicular cells colloid C-cells produce calcitonin (know about hormone but don’t worry about identifying on slides)

Thyroid Follicles produces and stores thyroid hormone follicular cells simple cuboidal epithelium colloid contains thyroglobulin a protein precursor to thyroid hormone

Thyroid Hormones hormone nameabbreviationmajor effects thyroid hormoneTH regulates metabolic rate of the entire body important in development of the nervous system calcitonin stimulates bone formation, lowering serum calcium levels not a physiologically significant hormone inhibits PTH secretion

Parathyroid 4 bean sized glands on posterior surface of the thyroid lobes

Parathyroid oxyphil cells and chief cells

Parathyroid Hormone hormone nameabbreviationmajor effects parathyroid hormonePTH responsible for closely regulating serum calcium level hormone is released when serum calcium is low increases bone reabsorption by osteoclasts, releasing calcium and phosphate into blood increases calcium reabsorption by kidneys decreases phosphate reabsorption by kidneys increases vitamin D activation by kidneys which results in increased intestinal calcium absorption Net result is increased serum calcium and decreased serum phosphorus

Pancreas Located in abdomen in C-loop of the duodenum Has exocrine and endocrine function exocrine digestive enzymes into duodenum endocrine secretes insulin and glucagon to control blood glucose levels

Pancreas Acinar Cells exocrine function dark staining portion Islets of Langerhans light staining “spots” endocrine function alpha cells secrete glucagon beta cells secrete insulin

Pancreas Acinar Cells exocrine function dark staining portion Islets of Langerhans light staining “spots” endocrine function alpha cells secrete glucagon beta cells secrete insulin

Pancreatic Hormones hormone namemajor effects insulin released in response to high blood sugar increases cellular absorption of glucose (esp skeletal muscle) increases rate of lipogenesis and formation of glycogen in the liver glucagon released in response to low blood sugar increases rate of gluconeogensis (formation of sugar from fat and protein) increases lipolysis and glycogenoloysis

Adrenal Gland Pair of glands resting on the superior aspect of the kidneys

Adrenal Gland cross section reveals two layers adrenal cortex secretes aldosterone, glucocorticoids, and adrenal androgens adrenal medulla secretes epinephrine and norepinephrine

Adrenal Gland Adrenal cortex has three layers zona glomerulosa aldosterone zona fasciculata glucocorticoids (cortisone) zona reticularis adrenal androgens adrenal medulla secretes epinephrine and norepinephrine

Adrenal Gland Adrenal cortex has three layers zona glomerulosa aldosterone zona fasciculata glucocorticoids (cortisone) zona reticularis adrenal androgens adrenal medulla secretes epinephrine and norepinephrine

Adrenal Gland

Adrenal Hormones hormone namelayermajor effects aldosterone (mineralocorticoid) zona glomerulosa increases blood volume by causing kidneys to retain sodium (where sodium goes water goes too) in exchange for potassium increased blood volume will increase blood pressure cortisone (glucocorticoid) zona fasciculata released in response to stress increases formation of glucose from protein and fat breakdown decreases inflammation adrenal sex steroids (DHEA) zona reticularis initiates pubertal changes precursors to estrogen in postmenopausal women epinephrine (adrenal only), norepinephrine (adrenal and sympathetic NS) adrenal medulla fight or flight response increase heart rate, increase skeletal muscle blood flow, decrease skin blood flow

Other Hormones hormone nameabbreviationmajor effects Melatonin involved in circadian rhythms increased melatonin secretion in the evening to prepare for sleep erythropoietinEPO released by kidneys to stimulate RBC production