VTPP 427 - Endocrine System (Hormones)

How many & What hormones does the hypothalamus release?

7

Thyrotropin-Releasing Hormone (TRH)

Corticotropin-Releasing Hormone (CRH)

Gonadotropin-Releasing Hormone (GnRH)

Growth Hormone-Releasing Hormone (GHRH)

Somatostatin (Growth Hormone-Inhibiting Hormone) (GHIH)

Prolactin-Releasing Hormone (PRH)

Dopamine (Prolactin-Inhibiting Hormone) (PIH)

What is the function of TRH?

Stimulates the release of TSH & Prolactin

What is the function of CRH?

Stimulates release of ACTH

What is the function of GnRH?

Stimulates the release of FSH & LH

What is the function of GHRH?

Stimulates the release of GH

What is the function of Somatostatin (GHIH)

Inhibits release of GH & TSH

What is the function of PRH?

stimulates the release of prolactin

What is the function of Dopamine (PIH)

Inhibits the release of prolactin

What does it mean to be Hypophysiotropic?

a hormone that stimulates or acts on the hypophysis

What are the three families that hormones can be grouped into?

Glycoproteins, Pro-opimelanocortin (POMC), and Growth Hormone/Prolactin

What hormones fall into the Glycoprotein family?

TSH, FSH, LH

What hormones are derived from POMC protein?

ACTH, Beta-endorphins, alpha-MSH, Beta-MSH, & Gamma-MSH

What are the hormones of the Posterior Pituitary?

Oxytocin & Vasopressin (ADH)

Oxytocin (Target Cell + Function)

Target: Uterus + Mammary Glands

Function: Increases contractility and causes milk let-down

Vasopressin/ADH (Target Cell + Function)

Target: Kidney Tubules + Arterioles

Function: Increase Water Reabsorption + Produce Vasoconstriction

How many & What hormones does the anterior pituitary release?

6

Thyroid-Stimulating Hormone (TSH)

Adrenocorticotropic Hormone (ACTH)

Growth Hormone (GH)

Follicle-Stimulating Hormone (FSH)

Luteinizing Hormone (LH)

Prolactin (PRL)

TSH (Target Cell + Function)

Target: Thyroid Follicular Cells

Function: Stimulates T3 & T4 secretion

ACTH (Target Cell + Function)

Target: Adrenal Cortex (Zona Fasciculata + Zona Reticularis)

Function: Stimulates Cortisol secretion

GH (Target Cell + Function)

Target: Bone and Soft Tissue

Function: is essential but not fully responsible for growth; by means of IGF-1, indirectly stimulates protein anabolism and growth of bones and soft tissues; direct metabolic effects include mobilizing fats and conserving glucose

FSH (Target Cell + Function)

Target: Liver; Ovarian Follicle (Females); Seminiferous Tubules in Testes (Males)

Function: Liver --> stimulates IGF-1 secretion

Ovarian Follicle --> promotes follicular growth and development + stimulates estrogen secretion

Seminiferous Tubules --> Stimulates Sperm Production

LH (Target Cell + Function)

Target: Males --> Interstitial Cells

Females --> Ovarian Follicle + Corpus Luteum

Function: Interstitial Cells --> Stimulates Testosterone secretion.

Females --> Stimulates ovulation, corpus luteum development, and estrogen and progesterone secretion

PRL (Target Cell + Function)

Target: Mammary Glands (Female)

Function: Promotes breast development; stimulates milk secretion

What hormone does the pineal gland secrete and where does this hormone target?

Melatonin

Targets brain, anterior pituitary, reproductive organs, immune system, and possibly others.

What is the function of Melatonin?

Entrains body's biological rhythm with external cues; inhibits gonadotropins; its reduction likely initiates puberty; acts as an antioxidant; enhances immunity

What Hormone does the Thyroid Gland Follicular Cells secrete and where does this hormone target?

Tetraiodothyronine (T4) & Triiodothyronine (T3)

Targets most cells

What is the function of T3 & T4?

Increase metabolic rate; essential for normal growth and nerve development

What hormone does the Thyroid Gland C cells secrete and where does this hormone target?

Calcitonin

Targets bone

What is the function of Calcitonin?

Decreases plasma Calcium concentration

What hormone does the Zona glomerulosa secrete and where does this hormone target?

Aldosterone (mineralcorticoid)

Targets the Kidney tubules

What is the function of Aldosterone?

Increase Na+ reabsorption and K+ secretion

What hormone does the Zona Fasciculata secrete and where does this hormone target?

Cortisol (glucocorticoid)

Targets Most Cells

What is the function of Cortisol?

Increases blood glucose at the expense of protein and fat stores; contributes to stress adaptation.

What hormone does the Zona Reticularis secrete and where does this hormone target?

Androgens (dehydroepiandrosterone)

Targets Females bone and brain

What is the function of Androgens?

Is responsible for pubertal growth spurt and sex drive

What hormone does the adrenal medulla secrete and where does this hormone target?

Epinephrine & Norepinephrine

Targets Sympathetic receptor sites throughout the body

What is the function of Epinephrine/Norepinephrine?

Reinforce sympathetic nervous system; contribute to stress adaptation and blood pressure regulation.

What type of receptor is involved in the cAMP/PKA; IP3/Ca2+; and DAG/PKC signal pathway?

G-protein-coupled receptors in surface membrane

What is the outcome of hormones binding to membrane receptors stimulating secondary pathways?

Alters preexisting designated proteins

What hormones use the cAMP/PKA pathway

(13)

Hypothalamus --> (PTH, CRH, GHRH, Somatostatin)

Anterior Pituitary --> (LH, FSH, TSH, ACTH)

Posterior Pituitary --> (Vasopressin)

Adrenal Medulla --> (Epinephrine, Norepinephrine)

Thyroid --> (Calcitonin)

Pancreas --> (Glucagon)

What hormones use the IP3/Ca2+; DAG/PKC pathway?

Hypothalamus --> (TRH, GnRH)

Posterior Pituitary --> (Oxytocin)

What hormones use the Tyrosine Kinase Signal Pathway?

Insulin; Insulin-like Growth Factors (IGF-I & IGF-II)

What hormones use the JAK/STAT signal pathway?

Growth Hormone & Prolactin

What type of receptor is involved in hormone-response elements on DNA?

Intracellular cytoplasmic or nuclear receptors

What is the outcome of hormones binding to intracellular cytoplasmic or nuclear receptors?

Turns on gene transcription, leading to synthesis of designated protein

What hormones use intracellular or nuclear receptors?

All lipophilic hormones (T3, T4, Cortisol, aldosterone, testosterone, estrogen, progesterone, Vitamin D)