1- General principles of endocrinology

Hormone

chemical messangers that enter blood and influence cells at a distance

what do hormones link ?

organ systems

how do endocrine glands work

secrete hormones that diffuse in interstitium to blood cells and are carried to distant target cells

Exocrine glands

secrete through ducts onto bodys surface like organ lumen and skin

example of exocrine signaling

pancreatic enzymes in gut and sweat

Endocrine gland features

• no ducts

• only hormones

• into bloodstream

exocrine glands function

• ducts

• secrete enzymes, mucus, sweat,

• secrete onto lumen or body surface

Paracrine signlaing

secreted substances works on nearby cells

Autocrine signalin

secreted substance works on the same cell

A single gland can secrete

many hormones

is a hormone only produced by one gland?

No, more than one

A chemical acting as a hormone in one system

can act as a neurotransmitter in another

Amines are derived from

amino acid tyrosine

Steroid hormones are derived from

cholesterol

Two classes for amine hormones

thyroid hormones- T3 and T4

catecholamines- NE, epinephrine, dopamine

Where is dopamine released from

the hypothalamus

where are epinephrin and norepinephrin released from

adrenal medulla

where are thyroid hormones released from

the thyroid gland

Precursoers for hormones

preprohormones and prohormones from endoplasmic reticulum

How are precursor proteins transporter

in vesicles until ended and secreted by exocytes

where is insulin stored

secretory vesicles

Water soluble hormones

circulate free in bloodstream and bind to cell surface receptors

example of water soluble hormones

catecholamines and peptides

Examples of steroid hormones

cortisol, aldosterone, testosterone, estradiol

Why is vitamin D a steroid hormone

produced from cholesterol and has widespread effects

how does vitamin D become active

made in skin and goes through modifications in the liver and kidney

Where are glucocorticoids made

adrenal cortex

where are testosterone and estrogen made

gonads

where is vitamin D made

the skin

Lipid soluble hormones

diffuse across plasma membranes and bind intracellular receptors

What do lipid soluble hormones regulate

transcription in the nucleus

How are hydrophobic hormones transported

transport proteins

what is the hypothalamus

coordinating center for metabolic functions like body temp hunger sleep etc

What does the hypothalamus link

nervous to the endocrine

The pituitary

beneath hypothalamus and connected to infundibulum made of anterior and posterior pituitary

Another name for the anterior pituitary

adenohypophysis

What tissues are the anterior pituitary made from

same as the tissue of roof of mouth

posterior pituitary is also called

neurohypophysis

What is posterior pituitary made of

neural components of the hypothalamus

Where do axons from neurons in the hypothalamus project to in the posterior pituitary

capillaries

What hormones are released from the posterior pituitary

oxytocin and vasopressin

What does oxytocin do

contracts uterine smooth muscle during childbirth and during lactation for milk release

ADH. Vasopressin

stimulates contraction of smooth muscle to increase blood pressure

increase water reabsorption in collecting duct to decrease urine output

How are the hypothalamus and anterior pituitary connected

circulation via hypothalamo-hypohphyseal portal vessels

How do hormones releaased in adenohypophysis traveling

down portal vessels to anterior pituitary

tropic hormones

hormones that act on other endocrine glands

Hypophysiotropic hormones

hormones made in hypothalamus and act on anterior pituitary

hypophysiotropic hormones made in hypothalamus control the secretion of

• tropic hormone from anterior pituitary controlling a hormone from some other endocrine gland

Sequncey of anterior pituitary events called

HPX

What can a hypophysiotropic hormone be

A releasing factor or an inhibiting factor on the posterior pituitary

Gonadtropin-releasing hromone (GnRH)

release of gonadotropins from anterior pituitary

where do gonadotropins act

gonads- testes and ovaries

2 types of gontropins

Follicle stimulating hormones

luteinizing hormone

GHRH

growth hormone releasing hormones, encourages release from pituitary

SST

somatostatin , inhibits GH release from pituitary

Where does GH act

liver and other tissues to encourage body growth

Another name for GH

somatotropin

TRH

thyrotropin releasing hormone, stimulates thyroid stimulating hormone

TSH

thyroid stimulating hormone

Another name for TSH

thyrotropin

what does thyroid hromone do

influences metabolic rate throughout body

Doparmine

inhibits production of prolactin in anterior pituitary

Why is prolactin special

does not trigger 3rd hormone release w

what does prolactin do

acts on breast tissue to stimulate lactation

CRH

corticotropin releasing hormone, made by hypothalamus, releases ACTH

ACTH

released in anterior pituitary and produces cortisol, called corticotropin

Hyposecretion

too little hormone is released

hypersecretion

too much hormone is released

hyporesponsivenes

target cells do not respond well to hormones

hyperresponsiveness

target cells over respond to hormone