Endocrine System

General Function

is a group of organs that secrete hormones

helps maintain homeostasis by coordinating and regulating systems throughout the body

Amino acid, includes amines,peptides,proteins

water soluble, except thyroid hormones that are fat soluble

Chemical Classification & Mechanism of Hormone Receptors

Lipids which include steroids

Control of Hormone Secretion

Tropic Hormones

Blood composition

downregulation: allows the target cells to be less reactive to the excessive hormone levels if there is an increase in the level of hormone circulating in the bloodstream

upregulaton: increase number or sensitivity of receptors for that hormone

feedback loop: keeps homeostasis in check, either negative or positive

Control by Hypothalamus & Pituitary Gland

hypothalamus-pituitary complex coordinates cell-to-cell communication between the nervous and endocrine systems

hypothalamus produces hormones that have direct effects on body tissues, these hormones are secreted within the posterior pituitary

reproduction, growth, development, defense against stress, water, electrolyte, nutrient balance, energy balance, cellular metabolism

fat soluble, steroid hormone must be attached to a transport protein when traveling in the bloodstream

controls release of other hormones, help in the rapid release of a particular hormone, can be releasing or inhibiting

hypothalamus secretes tropic hormones into the blood vessels within the hypothalamus, these affect the anterior ptuitary

Major Hormones

Tropic

SS - Somatostatin. This one along with #6 regulates growth hormone levels. Somatostatin used to be called GHIH (growth hormone inhibiting hormone).

GHRH - Growth hormone releasing hormone

GnRH - Gonadotropin releasing hormone. This will stimulate the anterior pituitary to produce the sex hormones.

CRH - Corticotropin releasing hormone. This will stimulate the anterior pituitary to produce ACTH (adrenocorticotropic hormone).

PIH - Prolactin inhibiting hormone. This one along with #2 regulates prolactin levels.

PRH - Prolactin releasing hormone.

TRH - Thyrotropin releasing hormone. This will stimulate the anterior pituitary to produce TSH (thyroid stimulating hormone).

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OT - Oxytocin

ADH - Antidiuretic hormone

These two hormones are made in the neurons of the hypothalamus and travel to the axonal terminal which is in the posterior pituitary.

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anterior pituitary produces seven hormones:

FSH - follicle stimulating hormone

LH - leutinizing hormone

ACTH - adrenocorticotropic hormone

GH - growth hormone

TSH - thyroid stimulating hormone

MSH - melanocyte stimulating hormone

PRL - prolactin

Thyroid

both T3 and T4 is to regulate metabolism by breaking down carbohydrates and fats along with synthesizing proteins. T3 is more effective but T4 is more abundant.