Endocrine System

Endocrine System – all organs that tissues that produce hormones
Endocrine / Exocrine Glands

Hormone – chemical that is secreted into extracelluar fluid and carried by the blood
Act as a distance from the source
Only target with a receptor

Paracrine Regulators – DO NO TRAVEL IN BLOOD, allows cells of organs to related to each other

Pheromones – chemical released into the air (environment) to communicate among people

Neurohormones – i.e. norepinephrine – heart, liver, blood vessels during stress

Directly or Indirectly – hormones are released by the nervous system


Classes of Hormones
1. Peptides and Proteins – glycoproteins
2. Amino Acid Derivatives - TYROSINE
a. Catecholamines
b. Thyroid Hormones (tyrosine, T3, and T4, trioidothyronine)
c. Melatonin
i. Epinephrine and norepinhrine
3. Steroids
a. Sex steroids
b. Corticosteroids

EITHER Hormones are
1. Lipophilic – fat-soluble, NO POLAR
a. Steroids, thyroid hormones (tyrosine, and iodine)
b. Intra – cellular receptors
c. Derived from Cholesterol
d. Retinoids / VITAMIN A
2. Hydrophilic- water loving, POLAR

Endocrine Action – controls physiology with chemical signals from one part of the body to another, target cell undergoes a biological response.

Endocrine – born via bloodstream
Paracrine – close to local environment
Autocrine – acting on secreting cell
Neurocrine – neural cells that release chemical signals into bloodstream


Hypothalamus – releasing hormones
Tropic (stimulating) hormones – from pituitary to act on another endocrine gland
Non Tropic Hormones – from an endocrine gland to target cells

All cells respond to multiple hormones, hormones via receptors, receptors either at cell surface or intracellular

Paracrine Regulators – occurs in most organs,

1. Growth Factors – promote growth and cell division
a. Epidermal growth factor – skin
b. Nerve – nerve
c. Insulin-like growth factors – BONE
d. Cytokines – Immune System

2. Endothelium – rich source of paracrine regulators
a. Nitric Oxide (NO)
b. Endothelin – vasoconstriction
c. Bradykinin – vasodilation

3. Prostaglandins -diverse group of fatty acids that are produced almost in all organs
a. Regulates – smooth muscle, blood vessels, dilation,
b. NONSTEROIDAL ANTI INFLAMMATORY DRUGS
c. Immune system
d. Reproductive
e. Digestive
f. Circulatory
g. Urinary
h. Respiration

Receptor Kinases – for some peptide hormones ( like insulin) the receptor itself is a kinase (enzyme)
Other peptide hormones (like growth hormones) the receptor is NOT A KINASE, but rather is activates INTRACELLULAR Kinases

Hydrophilic Hormones- linked to second messenger protein called G PROTEINS (increase the second messenger molecules)
Second Messenger Stystems – many cAMP, DAG, IP3 ,

Lipophlic Hormones – pass thought the target cell’s plasma membrane and binds to intracellular receptor proteins, then binds to parts of the DNA, activates genes and regulates target cells





Peptides and Glycoproteins – too large to enter cell membrane (non, epe)
Binds to receptor located on the outer surface of the plasma membrane

Major Endocrine Glands –
a. Hypothalamus g. Adrenal Medulla
b. Anterior Pituitary h. Adrenal Cortex
c. Posterior Pituitary i. Pancreas
d. Pineal j. Ovaries
e. Thyroid k. Testes
f. Parathyroids l. Placenta



Pituitary Gland (aka hypophysis) – hangs from the hypothalamus
a. Anterior Pituitary – glandular, TROPIC HORMONES or TROPINS
a. Peptide Hormones, Protein Hormones , Glycoprotein hormones
i. Produces GROWTH HORMONES -muscles and bones
ii. OTHER??????
iii. Direct or indirect
iv. Releasing hormomes and inhibiting hormones,
v. HYPOTHALAMOHYPOPHYSIAL PORTAL SYTSEM
vi. NEGATIVE FEEDBACK or FEEDBACK INHIBITION
vii. Dwarfism, gigantism
b. Posterior Pituitary – fiberous, comes from brain, directly connected to hypothalamus by tract of axons
i. Stores and releases two hormones that are produced by cell bodies in the hypothalamus
ii. NEURENDOCRINE RELEX
iii. Anitdiuretic hormones (ADH) – urine production
iv. Oxytocin- like ADH – 9 amino acids – reproductive behavior




Thyroid – behind the Adam’s apple (front of neck), promote growth in kids, maturation of central nerous system, binds to nuclear receptors, regulated carbs and lipid breakdown,
THYROID HORMONES
a. THYROXINE – set basal metabolic rate, HIGH AND LOW –HYPO-HYPER
b. Triiodothryonine
c. Calcitonin
a. A peptide hormone
b. Helps with the uptake of CALCIUM IONS INTO BONES



Parathroid Gland – 4 small glands attached to thyroid
Produce–PARATHYOID HORONE (PTH) because of FALLING CA2+ in blood
Activation of Vitamin D
PTH – sunlight VITAMIN D
CALCIUM HOMEOSTASIS

Adrenal Gland –above the kidneys,
INNER –Adrenal Medulla
SECRETES EPINEPHRINE & NOREPINEPHRINE (help!!! alarm cells)

OUTER – Adrenal Cortex
Corticosteriods- hormones from the adrenal cortex
Glucocorticoids (cortisol)
Mineralocorticoids (aldosterone) reabsord Na and excrete K

Anterior pituitary – with hormone ACTH


Pancreas – next to stomach, connected to the duodenum of the small intestine
ISLETS OF LANGERHANS – SCATTERED CLUSTERS OF CELLS THROUGHOUT THE PANCREAS
ISLETS – B cells of islet secrete INSULIN (lowers glucose)
A cells of islet secrete GLUCAGON (raised glucose)
Promotes the hydrolysis of glycogen in the liver and fat in adipose