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ENDOCRINE SYSTEM Review
PETER REONISTO, MD MOORPARK COLLEGE
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Nervous System vs. Endocrine System
3) Hormones travel more slowly than nerve impulses, the endocrine system tends to regulate slow processes such as growth and metabolism.
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1. “Pure” endocrine organs
Major Endocrine Organs Pineal gland Pituitary gland Thyroid gland Parathyroid gland Endocrine cells of the body contained in: Adrenal gland 1. “Pure” endocrine organs
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Major Endocrine Organs
Hypothalamus Endocrine cells of the body contained in: Thymus Pancreas 2. “Partly” endocrine organs Gonads
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CLASSES OF HORMONES AMINO ACID-BASED Most hormones Proteins
Modified amino acid peptides STEROIDS Lipid molecules derived from cholesterol Sex hormones Adrenal cortex hormones
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CONTROL OF HORMONE SECRETION
Humoral Neural Hormonal
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CONTROL OF HORMONE SECRETION
Humoral- influenced by plasma concentration of the substance. Low Ca2+ blood concentration Parathyroid gland Parathyroid gland Parathormone secretion Nephron, intestinal cells Action
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CONTROL OF HORMONE SECRETION
2. Neural- SNS stimulation Preganglionic SNS fibers Adrenal medulla Medulla of adrenal gland Adrenaline secretion Body Actions: “Fight, flight, or fright” response
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CONTROL OF HORMONE SECRETION
3. Hormonal-influenced by the amount of hormones in the plasma Releasing hormones Hypothalamus Releasing hormones Adenohypohysis Stimulating Hormones Thyroid gland Adrenal cortex Gonads (Testis) Thyroxine Cortisol Androgens Body Cortisol Androgens Increase Metabolic rate Anti-stress Sperm formation
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MAJOR ENDOCRINE ORGAN PITUITARY GLAND
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> Hypophyseal fossa
PITUITARY GLAND Or, hypohysis Secretes at least 9 major hormones Location: > Hypophyseal fossa Depression in the Sella turcica of the Spenoid bone
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ANATOMY: PITUITARY GLAND
infundibulum
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Anterior Pituitary Gland
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Adenohypophysis Pars distalis Pars intermedia Pars tuberalis
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Adenohypophysis Pars distalis Largest division
Contains 5 different endocrine cells that make and secrete 7 different hormones
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Pars distalis 5 CELL CLASSES:
1. Somatotrophic cell (most abundant) 2. Mammotrophic cells 3. Thyrotrophic cells 4. Corticotrophic cells 5. Gonadotrophic cells Growth Hormone (Somatotrophic Hormone / Somatotropin / GH) Growth of the entire body Prolactin (PRL) Breast milk production Thyroid Stimulating Hormone (TSH) Thyroid gland stimulation to release thyroid hormone Adrenocorticotropic Hormone (ACTH) Adrenal Cortex stimulation to release glucocorticoids Melanocyte Stimulating Hormone (MSH) Stimulates melanocytes to produce melanin pigment Follicle Stimulating Hormone (FSH) Gonads: maturation of sex cells; secretes sex hormones Gonadotropins Leutenizing Hormone (LH) Gonads: maturation of sex cells; secretes sex hormones
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Pars distalis 5 CELL CLASSES:
Growth Hormone (Somatotrophic Hormone / Somatotropin / GH) Growth of the entire body Act directly on non-endocrine target tissues Prolactin (PRL) Breast milk production M P G Thyroid Stimulating Hormone (TSH) Thyroid gland stimulation to release thyroid hormone Tropic Hormones - Regulate the secretion of hormones by other Endocrine glands Adrenocorticotropic Hormone (ACTH) Adrenal Cortex stimulation to release glucocorticoids F L A T Melanocyte Stimulating Hormone (MSH) Stimulates melanocytes to produce melanin pigment Follicle Stimulating Hormone (FSH) Gonads: maturation of sex cells; secretes sex hormones Leutenizing Hormone (LH) Gonads: maturation of sex cells; secretes sex hormones
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HYPOTHALAMIC CONTROL OF THE ADENOHYPOPHYSIS
Controlled by RELEASING HORMONES and INHIBITING HORMONES - Peripheral Endocrine gland Peripheral Endocrine gland Peripheral Endocrine gland Target cell Target cell
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HYPOPHYSEAL PORTAL SYSTEM
Hypothalamic neurons Releasing hormones are made in Hypothalamic neurons Primary capillary complex Releasing hormones are secreted at the neuron synapse To the primary capillary complex Releasing hormones goes to the Hypophyseal portal vein To the secondary capillary complex Secondary Capillary complex Releasing hormones leaves the plexus & attach to the adenohypophyseal cells Somatotropic Mammotropic Thyrotropic Corticotropic Gonatotropic
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Posterior Pituitary Gland
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Neurohypophysis 1. Median eminence 2. Infundibular stalk 3. Pars nervosa Median eminence Infundibular stalk Pars nervosa
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NEUROHYPOPHYSIS HORMONE PRODUCTION
Hormone produced at neuron cell bodies located at the SUPRAOPTIC and PARAVENTRICULAR nuclei of the Hypothalamus Hormones are transported along the axons (Hypothalamic-hypophyseal Tract) Upon stimulation, stored hormones are released in the capillary bed for distribution throughout the body Hormones are stored in dilated axon terminals called HERRING BODIES ADH Oxytocin
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NEUROHYPOPHYSIS: Hormones
CELL TYPE HORMONE TARGET/EFFECTS Neurons from supraoptic nucleus of hypothalamus Antidiuretic hormone (ADH, vasopressin) Stimulates kidneys (distal tubules and collecting tubules) to reclaim water from urine. Raises blood pressure by constricting peripheral arterioles when blood volume is low. Neurons from paraventricular nucleus of hypothalamus Oxytocin Initiates labor through uterine contraction Facilitates milk ejection from breast
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MAJOR ENDOCRINE ORGAN THYROID GLAND
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THYROID GLAND located in the anterior neck; on the trachea just inferior to the larynx
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PARATHYROID GLAND Located at the posterior surface of the thyroid
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PARATHORMONE FUNCTION: Increase blood Calcium level
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ADRENAL GLAND ADRENAL CORTEX ADRENAL MEDULLA Mineralocorticoid
Balance electrolyte Concentration (Na+/K+) --Inc Na+ Reabsorption --Inc K+ excretion --Inc water reabsorption Mineralocorticoid (Aldosterone) Glucocorticoid (Cortisol) Stress control Glucocorticoid (Cortisol) Produce sex hormone precursor (DHEA) ----Dehydroepiandrosterone---
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ADRENAL MEDULLA: Hormones
Simulate a “fight, fright, flight response”
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PANCREAS
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Other Endocrine Glands
Pineal Gland secretes melatonin regulates circadian rhythms Thymus Gland secretes thymosins promotes development of certain lymphocytes important in role of immunity Reproductive ovaries produce estrogens and progesterone testes produce testosterone placenta produces estrogens, progesterone, and gonadotropins
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