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Describe the endocrine system in general terms.
The endocrine system consists of endocrine glands that secrete specific hormones into the blood or surrounding interstitial fluid.
Compare endocrine responses and neural responses with respect to speed and duration.
Hormones causes changes in the metabolic activities in specific cells, and nerve impulses cause muscles to contract or glands to secrete. The action of hormones is relatively slow and the effects are prolonged, whereas the action of nerves impulses is fast and the effects are of short duration.
What is Endocrinology?
The study of endocrine glands, the hormones they secrete, and the effects they have on their target cells, or target tissues.
Define a hormone.
A chemical messenger secreted by an endocrine gland.
In what ways does the endocrine system illicit control over the body?
-Growth & Development
-Chemical/fluid balance
-Cellular metabolism
-Mobilization of body defenses.
1. How do endocrine glands release hormones? Do they have ducts?

2. What type of glands have ducts?
1. They do not have ducts, so hormones are released into interstitial space, then diffuse into the blood stream because they are highly vascularized.

2. Salivary glands
What are the three major types of hormones?
Amino acid based, lipid derived, and eicosanoids.
Describe amino acid based hormones.
Molecular size varies widely in this group - from simple amino acid derivatives, to peptides (short chains of amino acids), to proteins (long polymers of amino acids).
Describe lipid derived hormones.
Synthesized from cholesterol, only gonadal and adrenocortical hormones are steroids.
Describe the eicosanoids.
Biologically active lipids (made from arachidonic acid) that are highly localized. They are more hormone-like rather than true hormones, and include leukotrienes and prostaglandins.
1. What are paracrines?

2. What are autocrines?
1. Much more localized hormones, such as the triglyceride-like eicosanoids.

2. Cell produces hormones, reaction occurs in the cell itself.
What do hormones do?
-Alter membrane permeability/potential
-Stimulate synthesis of proteins (regulatory molecules)
-Enzymes: activate/deactivate
-Induce cellular secretion
-Stimulate mitosis
What are the 2 types of second-messenger systems?
The cyclic AMP signaling mechanism and the PIP2-Calcium signaling mechanism.
What are the 6 major steps of the cyclic AMP signaling mechanism?
1.Hormone (1st messenger) binds receptor.
2.Receptor activate G protein.
3.G protein activates adenylate cyclase.
4.Adenylate cyclase convertes ATP to cyclic AMP (2nd messenger).
5.Cyclic AMP activates protein kinases.
6.Protein kinases triggers responses of target cell (activate enzymes, stimulates cellular secretion, opens ion channels, etc).
What is different about the pip2-calcium signaling mechanism?
Calcium is realsed from intracellular storage sites and takes on a second-messenger role, either by directly altering the activity of specific enzymes and channels or by binding to the intracellular regulatory protein calmodulin.
What does calmodulin do?
It activates enzymes that amplify cellular response.
Which types of hormones use second messenger systems?
Generally amino acid derived and peptide hormones.
Specifically which hormones use the pip2 system?
TRH, ADH, GnRH, oxytocin, and epinephrine.
Which types of hormones use direct effect on transcription (direct gene activation).
Generally lipid derived hormones.
Target cells must have ______ for the hormone.
What causes the receptor to be activated?
-Blood level of hormone
-Receptor number on target cell/up and down regulation.
-Affinity between hormone and receptor.
What are the 5 steps in direct gene activation?
1.The steroid hormone diffuses trough the plasma membrane and binds an intracellular receptor.
2.The receptor-hormone complex enters the nucleus.
3.The receptor-hormone complex binds a hormone response-element (a specific DNA sequence).
4.Binding initiates transcription of the gene to mRNA.
5.The mRNA directs protein synthesis.
Which types of hormones are hydrophobic and use direct gene activation? Why?
Steroids, because the are hydrophobic and can get into the hydrophobic plasma membrane. Thyroid hormone also diffuses into the cell.
What is humoral stimulus?
Bloods levels of certain ions and nutrients stimulate endocrine glands.
What is neural stimulus?
Nerve fibers directly stimulate endocrine glands.
What is hormonal stimulus?
Another hormone stimulate endocrine gland.
What are the 2 major lobes of the pituitary gland, and what tissues are they made of?
Anterior: glandular tissue
Posterior: neural tissue
How is the pituitary gland attached to the brain?
By the pituitary stalk.
What is the infundibulum?
The portion of the pituitary stalk that connects the hypothalamus to the posterior lobe of the pituitary gland.
Which part of the pituitary secretes MSH?
The pars intermedia, which is part of the anterior pituitary.
What type of tissue makes up the posterior pituitary? What hormones does it release?
pars nervosa... ADH and Oxytocin
What type of tissue makes up the other part of the anterior pituitary?
pars distalis
The anterior pituitary releases _____ hormones. It is under control of the _______, and many of its hormones are called _____ hormones.
seven; hypothalamus; tropic
These type of hormones control the release of other hormones.
Tropic hormones
Name the direction of the hypophyseal portal system.
heart-->arteries-->capillaries in hypothalamus-->capillaries in pituitary-->veins-->heart.
What is the purpose of the hyophyseal portal system?
So releasing hormones can travel to other glands to stimulate the release of other hormones. It also allows the hypothalamus to control the pituitary gland.
What 7 hormones are released by the anterior pituitary gland?
1.Growth Hormone (GH)
2.Thyroid-stimulating hormone (TSH)
3.Adrenocorticotrophic hormone (ACTH)
5.Follice-stimulating hormone (FSH)
6.Luteinizing hormone (LH)
7. Melanocyte-stimulating hormone (MSH)
Which 2 hormones are released by the posterior pituitary?
1.Antidiuretic hormone (ADH)
What is a mixed gland? Which glands are considered mixed glands?
A gland that directly serves 2 or more body systems; pancreas & gonads.
Is growth hormone a tropic hormone?
Which major factors of growth hormone help cell growth?
-Increase cellular uptake of amino acids.
-Mobilize fats for energy needs
-Stimulates glycogen to glucose.
What stimulates the release of growth hormone?
GHRH release from the hypothalamus caused by low blood levels of GH.
Which gland is growth hormone released from?
Anterior pituitary
What secondary factors cause the release of growth hormone?
-increase in blood levels of amino acids
-low levels of fatty acids
Which conditions are caused by hypersecretion of growth hormone, and how are they treated?
-Gigantism before puberty
-Acromegaly after puberty
-Both treated by surgical removal of tumor or hypophysectomy (surgical removal of pituitary gland)
What condition is caused by hyposecretion of growth hormone? How is this condition treated?
-Dwarfism in children
-Treated by GH injections

-Which hormone from the hypothalamus stimulates TSH?
-What is the target tissue of Thyroid Stimulating Hormone (TSH)?
-What is the effect of this hormone?

-TRH (Thyrotopin) -Thyroid Gland
-Promotes growth & development of thyroid gland; stimulates synthesis & release of thyroid hormones.
-Which hypothalamus hormone stimulates ACTH (adrenocorticotropic hormone)?
-What is the target tissue of ACTH?
-What is the effect of ACTH?
-CRH (corticotropin)
-Adrenal Cortex
-Promotes growth & development of adrenal cortex; stimulates secretion of glucocorticoids
-Which hypothalamus hormone stimulates FSH (follicle-stimulating hormone) & LH (lutenizing hormone)?
-What are the target tissues?
-What is the effect of FSH & LH?

-GnRH (gonadotropin)
-ovaries & testes
-reproductive hormones
-Which hormone & other stimulus stimulates the release of Prolactin (PRL)?
-What is the target tissue?
-What is the effect?
-Decreased PIH sends a neural signal to the hypothalamus
-Mammary glands
-Promotes development of mammary glands & stimulates milk production
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