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Endocrine messenger system
second-messenger system of the body after the nervous system
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Hormone types
- AMINO ACID Based: include proteins, peptides and amines
- STEROIDS: made from cholesterol
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What hormones affect
certain tissues or TARGET cells or TARGET organs
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Target cells
Specialized by the cells having specific protein RECEPTORS
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2 Mechanisms of hormone action
- 1. DIRECT Gene activation: steroid hormone action, slower of the two
- 2. Second-messenger system: non-steroid hormone BINDS to a membrane receptor and gives off a message which activates an enzyme IN the cell
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Anterior Pituitary that effect NON-endocrine targets
- All Non-steroid (proteins)
- GH - Growth Hormone: Stimulates GROWTH of muscle & bones. REGULATED by hypothalamic releasing & inhibiting hormones
- PRL - Prolactin: Stimulates MILK production. REGULATED by hypothalamic hormones
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Anterior Pituitary that stimulate endocrine glands (TROPIC hormones)
- All Non-steroid (proteins)
- FSH Follicle-stimulating hormone: Stimulates PRODUCTION of OVARIES and SPERM. REG by Hypothalamic hormones
- LH - Luteinizing hormone: Stimulates OVULATION of eggs (females) and TESTOSTERONE (males). REG by Hypothalamic hormones
- TSH - Thyroid Stimulating Hormone: stimulates Thyroid Gland growth and activity. REG by Thyroxine in blood. REG by Hypothalamic hormones
- ACTH - Adrenocorticotropic hormone: Stimulates ADRENAL Cortex to Secrete GLUCOCORTICOIDS. REG by Glucocorticoids & Hypothalamic hormones
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Posterior Pituitary
- Oxytocin: non-steroid (peptide), stimulates CONTRACTION of uterus and breast milk. REGULATED by nervous System (hypothalamus)
- Antidiuretic Hormone (aka vasopressin): non-steroid (peptide), promotes H20 RETENTION by kidneys...can cause INCREASE IN BP from vasoconstriction. REGULATED by hypothalamus in response to SALT imbalance
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Thyroid Gland
- 2 iodine-containing hormones: T3 (triiodothyronine)- converts to T4 @ target tissues. T4 (thyroxine)- secreted by thryroid follicles
- T3/T4: non-steroid (amine). Stimulates METABOLISM. REG by TSH
- Calcitonin: non-steroid (peptide). Stimulates OSTEOBLAST activity, LOWERING blood Ca levels. REG by Ca levels in blood.
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Thyroid hormone DISORDERS
- GOITERS: Thyroid Gland ENLARGES (swollen neck) from Lack of IODINE
- CRETINISM: Due to HYPOsecretion of T4 (thryoxine) resulting in DWARFISM during childhood
- MYXEDEMA: Due to HYPOthyroidism in adults..results in physical & mental SLUGISHNESS
- GRAVE's DISEASE: Caused by HYPERThyroidism..results in INCREASED metabolism, heat intolerance, rapid heart beat, exophthalmos
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Parathyroid Gland
PTH - Parathyroid hormone: non-steroid (peptide). Stimulates OSTEOCLAST activity to RAISE blood Ca levels; stimulates kidneys & intestines to ABSORB more Ca. REG by Ca levels in blood.
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Hypothalamus
- Hormones produced: Oxytocin & ADH...to be released by the Post Pituitary
- Releasing and inhibiting hormones that REGULATE the anterior Pituitary
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Thymus
Thymosin: non-steroid (peptide). Produces types of WBC's, develops immune system by programming T lymphocytes
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Pancreas
- Insulin: non-steroid (protein). Work to lower blood glucose levels by allowing glucose to CROSS PLASMA membrane into cells from BETA cells. REG by blood glucose levels
- Glucagon: non-steroid (protein). Work to Raise blood glucose levels by allowing glucose to ENTER blood from ALPHA cells. REG by blood glucose levels
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Adrenal MEDULLA
Norepi & Epinephrine(adrenaline): non-steroid (amines). Raise Blood glucose level, INCREASE metabolism, Constrict blood vessels, Dialate lung passageways. REG by Sympathetic nervous system
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Adrenal CORTEX
- Glucocorticoids: STEROID hormones. Stimulated by INCREASED blood glucose. REG by ACTH (tropic hormone)
- Mineralocorticoids: STEROID hormones. Promote REABSORPTION of Na and EXCRETION of K in kidneys. REG by changes in blood pressure/volume/Na & K levels
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Adrenal Cortex DISORDERS
- Addison's disease: weak muscles and Bronze skin tone from lack of hormones
- Hyperaldosteronism: can be due to ACTH-releasing TUMOR. Excess water & Na retained..lead to High BP & Edema
- Cushing's syndrome: from tumor in middle area of cortex. 'Moonface,' 'buffalo hump' on upper back, High BP, hyperglycemia, weakening of bones, depression
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Mineralocorticoids
- Mainly consist of ALDOSTERONE, goal to REGULATE mineral content in blood
- REGULATES water & electrolyte balance
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Glucocorticoids
- Cortisol & Cortisone: released in response to INCREASED blood levels of ACTH (ACTH stimulates release of these glucocorticoids)
- Produces in Middle layer of cortex
- Aids with Normal cell metabolism
- Aids in resisting long term stressors
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Gonads
- All these gonadotropic hormones are REG by FSH and LH (in Ant pituitary) by NEGATIVE feedback
- Testes: Produce sperm & secrete ANDROGENS (STEROID hormones)such as testosterone. Support SPERM formation and Devel. of 2ndary SEX characteristics
- Ovaries: Produces eggs & secretes ESTROGENS and PROGESTERONES (STEROID Hormones).
- Est & Progest Stimulate growth of UTERINE lining. PROGEST gets breasts ready for LACTATION & helps implant EMBRYO in uterus. ESTROGEN involved in development of 2ndary SEX characteristics (breast), regulates menstrual cycle.
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Which are STEROID hormones vs. non-steroid
- Gonad hormones in testes (androgens) & ovaries (estrogen & progesterone) & Adrenal Cortex hormones (Glucocorticoids & Mineralcorticoids) are the only STEROID hormones.
- Everything else is non-steroid
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Pituitary Gland Facts
- Hangs by a stalk from the HYPOTHALAMUS in brain
- ANTERIOR pit: composed of GLANDULAR tissue
- POSTERIOR pit: composed of NERVOUS tissue
- Often called the 'master endocrine' gland
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Anterior Pituitary facts
- Mostly are regulated by negative feedback
- Since all are non-steroid (proteins), act through Second Messenger Systems
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Growth Hormone (GH) Facts
- Metabolic Hormone
- Effects related to growth of muscle and long bones
- Causes AA's to be built into PRoteins
- Causes fats to be broken down as ENergy source
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Growth Hormone Disorders
- Pituitary Dwarfism: hyposecretion of GH during childhood
- Gigantism: hypersecretion of GH during childhood (does not include enlarged organs, so organs can fail due to the increased stress put upon them)
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Pineal Gland
- On 3rd ventricle of brain
- Secretes MELATONIN
- Helps establish the body's SLEEP & Wake cycle
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