ENDOCRINE SYSTEM

Homeostasis & Controls Successful compensation –Homeostasis Failure to compensate –Pathophysiology Illness Figure 1-5: Homeostasis

ENDOCRINE SYSTEM Uses chemical signals for cell to cell Coordinates the Response to an endocrine signal occurs within

Chemical Regulating Systems: Overview Pheromones: organism to communication Hormones: cell to cell communication molecules –Made in –Transported by –Distant target tissue – physiological response

Paracrines and Autocrines Local Signal chemicals diffuse to Example: –Autocrine–receptor on same cell –Paracrine–neighboring cells Figure 6-1c: Direct and local cell-to-cell communication

Signal Made in cells Transported via Receptors on cells Long Distance Communication: Hormones Figure 6-2a: Long distance cell-to-cell communication

Figure 6-2b, c: Long distance cell-to-cell communication

Signal Pathways Signal molecule Receptor signal Target Response Figure 6-3: Signal pathways

Membrane associated e –External reactions –Internal reactions Receptors bind specific – Example: Hormones –Cell molecules Figure 5-6: Cell membrane receptor

HORMONE CLASSIFICATION Protein and A S

PEPTIDE HORMONES Consist of specific Synthesized as large Stored in membrane- compartments H

Surface binds T E Open Second messenger systems S Protein and Polypeptide Hormone Receptors Figure 7-5: Membrane receptors for peptide hormones

AMINE HORMONES Derived from the amino acid Includes thyroid hormones and catecholamines Stored until

Receptors –Surface –I–I Small size, group Examples –T–T –E–E Amine Hormones

STEROID HORMONES Precursor: C L Immediately released from the cell following synthesis

Cytoplasmic or receptors (mostly) Activate for protein synthesis Slower acting, longer Examples: cortisol, estrogen & t Steroid Hormones

Steroid Hormones: Action Figure 7-7: Steroid hormone action

Summary of the Endocrine System Figure 7-2-1: ANATOMY SUMMARY: Hormones

Figure 6-26: Negative and positive feedback

HYPOTHALAMUS Integrates functions that maintain chemical and temperature Functions with the system Controls the release of hormones from the anterior and posterior pituitary

Figure 11-3: Autonomic control centers in the brain

HYPOTHALAMUS Synthesizes & releases hypophysiotropic hormones: –T -releasing hormone (TRH) –C -releasing hormone (CRH) –G -releasing hormone (GnRH) –G hormone-releasing hormone (GHRH) –Growth hormone- hormone (GHIH) –P -releasing factor (PRF) –Prolactin- hormone (PIH)

HYPOTHALAMUS Synthesizes hypophysiotropic hormones in bodies of neurons located in the hypothalamus Transports hormones down the and stored in the nerve endings Secretion of hormones is in

HYPOTHALAMUS: Secretion of Hypophysiotropic Hormones Is influenced by Can be influenced by the state of the individual Delivered to the pituitary via the hypothalamic-hypophyseal portal system Usually initiates a -hormone sequence

Negative Feedback Controls: Long & Short Loop Figure 7-14: Negative feedback loops in the hypothalamicanterior pituitary pathway

Feedback Controls: Long & Short Loop Reflexes Figure 7-15: Control pathway for cortisol secretion

Endocrine Control: Three Levels of Figure 7-13: Hormones of the hypothalamic-anterior pituitary pathway

ANTERIOR PITUITARY

ANTERIOR PITUITARY HORMONES Growth Hormone (GH, Somatotropin): primary hormone responsible for regulating body growth, and is important in Thyroid-stimulating Hormone (TSH): stimulates secretion of hormone & growth of thyroid gland Adrenocorticotropic Hormone (ACTH): stimulates secretion by the adrenal cortex & promotes growth of adrenal cortex

ANTERIOR PITUITARY Follicle-stimulating Hormone (FSH): Females: stimulates growth & development of follicles, promotes secretion of estrogen by ovaries. Males: required for production Luteinizing Hormone (LH): Females: responsible for o, formation of corpus luteum in the ovary, and regulation of ovarian secretion of female sex hormones. Males: stimulates cell in the testes to secrete Prolactin: Females: stimulates development and milk production. Males: involved in testicular function

ANTERIOR PITUITARY Synthesis of different anterior pituitary hormone is by different cell populations. Corticotropes - Lactortropes - Somatotropes - Thyrotropes - Gonadotropes -

Hypothalamic stimulation–from Pituitary stimulation–from hypothalamic Hs Endocrine gland stimulation–from pituitary Hs Endocrine Control: Three Levels of Integration

Pathologies: Over or Under Production Figure 7-19: Negative feedback by exogenous cortisol

Pathologies: Due to Receptors Figure 7-20: Primary and secondary hypersecretion of cortisol

POSTERIOR PITUITARY Comprised of the endings of axons from cell bodies in the hypothalamus (s and paraventricular) Axons pass from the hypothalamus to the posterior pituitary via the tract Posterior pituitary hormones are synthesized in the cell bodies of in the supraoptic and paraventricular nuclei

POSTERIOR PITUITARY Hormones synthesized in the hypothalamus are transported down the axons to the endings in the posterior pituitary Hormones are stored in vesicles in the posterior pituitary until release into the Principal Hormones: Vasopressin &

Figure 7-12: Synthesis, storage, and release of posterior pituitary hormones

POSTERIOR PITUITARY Oxytocin: Synthesized as the precursor hormone: Action primarily on the Increases contraction of smooth muscle of Vas Deferens

POSTERIOR PITUITARY Vasopressin Plasma osmolality is monitored by osmoreceptors in the hypothalamus Increases in plasma osmolality stimulates secretion of Small changes above normal plasma osmotic pressure ( 285 mosm/kg) stimulate release of

POSTERIOR PITUITARY Vasopressin secretion also stimulated by: 1.Large in blood volume 2.Decreases in

POSTERIOR PITUITARY Vasopression Action: Decreases excretion by kidneys (V2 receptors) Constricts (V1 receptors) Increases adrenocorticortropin Hormone (V receptors)

Summary of the Endocrine System Figure 7-2-3: ANATOMY SUMMARY: Hormones

Summary of the Endocrine System Figure 7-2-2: ANATOMY SUMMARY: Hormones

Endocrine Disorders Acromegaly – excessive – large hands, feet, body size respiratory and circulatory problems

Grave’s Disease – bulging eyeballs, nervousness, elevated pulse, wgt. loss from too much Bone Fractures – excessive Cushing’s - moon face, poor immune sys. – caused by ↑ Increased hair growth, masculinazation – caused by ↑ Diabetes mellitus – low insulin – symptoms = 1.Polyuria ↑sugar in kidneys (↑water in urine 2.Polydipsia ↑thrist 3.Polyphagia ↑hunger because sugar is not being used.