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 GlandDivided into two parts

Anterior4 hormones control release of other hormones

adrenocorticotropic hormonethyroid stimulating hormonefollicle stimulating hormoneluteinizing hormone

2 hormones act directly(human) growth hormoneprolactin

Posteriortwo hormones which act directly

antidiuretic hormoneoxytocin

Pituitary GlandHypothalamic 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

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 pituitaryanterior pituitary

Anterior

more cellular due to amount of hormones manufactured

Posterior

mostly acellular, contains primarily axons from hypothalamus

Pituitary Gland

posterior pituitaryposterior pituitary

Anterior

more cellular due to amount of hormones manufactured

Posterior

mostly acellular, contains primarily axons from hypothalamus

Anterior Pituitary Hormoneshormone name abbreviation major effects

growth hormone hGH • stimulates growth of bones, cartilage, muscle

• timing and amount released determines body size

prolactin PRL • 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 hormone

LH • initiates ovulation, maintains corpus luteum• regulates testosterone production in males

Posterior Pituitary Hormones

hormone name abbreviation

major effects

antidiuretic hormone

ADH • reduces urine output by increasing water reabsorption in the kidney

• plays small role in blood pressure regulation

oxytocin OT • causes uterine contractions in labor• causes milk ejection in lactating

mothers

Thyroid

Bilobedlocated just under the cricoid cartilage

Thyroid

Folliclesproduces and stores thyroid hormone

follicular cellscolloid

C-cellsproduce calcitonin (know about hormone but don’t worry about identifying on slides)

Thyroid

Folliclesproduces and stores thyroid hormone

follicular cellssimple cuboidal epithelium

colloidcontains thyroglobulin a protein precursor to thyroid hormone

Thyroid Hormones

hormone name abbreviation major effects

thyroid hormone TH • 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 name abbreviation major effects

parathyroid hormone

PTH • 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 duodenumHas exocrine and endocrine function

exocrinedigestive enzymes into duodenum

endocrinesecretes insulin and glucagon to control blood glucose levels

Pancreas

Acinar Cellsexocrine functiondark staining portion

Islets of Langerhanslight staining “spots”endocrine function

alpha cells secrete glucagonbeta cells secrete insulin

Pancreas

Acinar Cellsexocrine functiondark staining portion

Islets of Langerhanslight staining “spots”endocrine function

alpha cells secrete glucagonbeta cells secrete insulin

Pancreatic Hormones

hormone name major 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 glomerulosaaldosterone

zona fasciculataglucocorticoids (cortisone)

zona reticularisadrenal androgens

adrenal medullasecretes epinephrine and norepinephrine

Adrenal Gland

Adrenal cortex has three layers

zona glomerulosaaldosterone

zona fasciculataglucocorticoids (cortisone)

zona reticularisadrenal androgens

adrenal medullasecretes epinephrine and norepinephrine

Adrenal Gland

Adrenal Hormones

hormone name layer major 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 name abbreviation major effects

Melatonin • involved in circadian rhythms• increased melatonin secretion in the evening to prepare for sleep

erythropoietin EPO • released by kidneys to stimulate RBC production