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Endocrine System

Endocrine System. Chp 13. Endocrine System : Regulates body functions with Hormones. Hormones : Produced by endocrine glands [e.g. pituitary] Circulate in the blood stream Steroids - lipid soluble Nonsteroids - not lipid soluble Often interact with nervous system

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Endocrine System

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  1. Endocrine System Chp 13

  2. Endocrine System: Regulates bodyfunctions with Hormones Hormones: • Produced by endocrine glands [e.g. pituitary] • Circulate in the blood stream • Steroids - lipid soluble • Nonsteroids - not lipid soluble • Often interact with nervous system • Act on specific cells [target cells] in the body

  3. Endocrine System Characteristics • Access to every cell • Each hormone acts only on specific target cells • Target cells have receptors for specific hormones • Endocrine control slower than nervous system • Endocrine & nervous systems interact

  4. Steroid Hormone Action on a Target Cell Figure 13.2

  5. Classification of Hormones: Steroid Steroid Hormones: • Lipid soluble, chemically derived from cholesterol • Enter target cells • Activate specific genes to produce specific proteins • Slower acting than nonsteroid hormones, minutes to hours

  6. Nonsteroid Hormone Action on a Target Cell Figure 13.3

  7. Classification of Hormones: Nonsteroid Nonsteroid hormones: • Water soluble • Bind to receptors on target cell membranes • Work through intermediate mechanisms to activate existing enzymes • Faster action than steroid hormones, seconds to minutes

  8. Role of Negative Feedback Loops Figure 13.4

  9. Hypothalamus and the Posterior Pituitary Gland Posterior pituitary gland: Connection to hypothalamus: hormones made in hypothalamus, stored in posterior pituitary Hormones: nonsteroidal operate here • Antidiuretic hormone (ADH): conserves water in kidneys, regulates water balance in body • Oxytocin: causes uterine contractions during labor & milk ejection through neuroendocrine reflex

  10. Hypothalamus & the Anterior Pituitary Gland Anterior pituitary gland: Connection to hypothalamus: releasing and inhibiting hormones from hypothalamus travel to pituitary through pituitary portal system Hormones: nonsteroidal operate here • ACTH- stimulates adrenal cortex • TSH- acts on thyroid gland • FSH, LH, Prolactin- related to control of reproductive cycles and lactation • Growth Hormone- widespread effects on body

  11. Pituitary Disorders • Hypersecretion of ADH - excessive water retention • Diabetes Insipidus - hyposecretion of ADH, inability to conserve water appropriately • Gigantism- hypersecretion of growth hormone • Pituitary Dwarfism- hyposecretion of growth hormone

  12. Pancreas: Endocrine Functions include Hormones secreted by islets of Langerhans are Nonsteroidal: • Glucagon - raises blood sugar • Insulin- lowers blood sugar

  13. Roles of Insulin and Glucagon in Regulating Blood Glucose Figure 13.9

  14. Adrenal Glands: 2 small endocrine glands located just above kidneys Adrenal cortex - secretes steroid hormones Produces small amounts of estrogen & testosterone Produces: • Cortisol [regulates blood glucose] • Aldosterone [regulates sodium & potassium]

  15. Adrenal Glands: Medulla Adrenal medulla- secretes nonsteroid hormones Secretion: stimulated by sympathetic nervous system Nonsteroidal hormones that control metabolism, blood pressure & heart rate • Epinephrine [adrenaline] • Norepinephrine They both enhance function of sympathetic nervous system (Fight or Flight Response)

  16. Thyroid Gland • Secretion: mediated through hypothalamus-pituitary secretions • Secretes Steroidal hormones: • Thyroxine (T4) and Triiodothyronine (T3) - both regulate production of ATP from glucose, affects metabolic rate • Calcitonin: lowers blood calcium levels

  17. Parathyroid Glands • Secretion: response to lowered blood calcium levels • Hormone: Parathyroid hormone (PTH), nonsteroidal • Removes calcium and phosphate from bone • Increases absorption of calcium by the digestive tract • Increases renal retention of calcium and excretion of phosphate

  18. Testes Hormone secreted = Testosterone (steroidal) Functions: • Regulates development and normal functioning of sperm, male reproductive organs, male sex drive • Development of male secondary sex characteristics

  19. Ovaries Hormones (steroidal) & functions: • Estrogen- initiates development of secondary sex characteristics, regulates menstrual cycle • Progesterone - regulates menstrual cycle

  20. Other Chemical Messengers • Histamine - inflammation • Prostaglandins - local control of blood flow • Growth factors - local acting/ mitotic activity

  21. Disorders of the Endocrine System Thyroid Disorders: • Hypothyroidism - underactivity of thyroid • Children: slows body growth, brain development & delays puberty • Adults: causes edema, weight gain, lethargy, low body temp. • Hyperthyroidism: [Graves Disease] • Overactive thyroid • Causes- Increased BMR, hyperactivity, nervousness, weight loss

  22. Adrenal Gland Disorders: • Addison’s Disease: failure of adrenal cortex to secrete sufficient cortisol & aldosterone • Lowers blood glucose & sodium • Symptoms: Chronic fatigue, weakness, weight loss & abdominal pain • Cushing’s Syndrome: excessive cortisol produced • High blood glucose & reduced muscle mass • Retension of too much salt & water • Symptoms: weakness & fatigue, edema, high blood pressure

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