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.