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Endocrine System

Function
1. Regulate growth
2. Use food to produce energy
3. resistance to stress
4. Ph of body fluids and fluid balance
5. Reproduction
Characteristics
1. Consists of endocrine glands that secrete chemicals called hormones
2. Endocrine vs. exocrine glands
  1. Endocrine glands
    1. Ductless glands, secrets it's product (hormone) directly into the blood
  2. Exocrine glands
    1. Secrets it's product into a duct to be taken to be taken to a cavity or surface
3. Types of hormones
  1. Amines
    1. Structural variations of amino acid tyrosine
    2. Includes thyroxine from thyroid gland
    3. Epinephrine + norepinephrine from the adrenal medulla
  2. Proteins
    1. Chains of 50-200 amino acids
      1. Short chains of amino acids (Peptides)
        Antidiuretic hormone + Oxytocin, Peptide hormones of 9 amino acids each
        Synthesized by the hypothalamus
    2. Insulin from pancreas
    3. GH from anterior pituitary gland
    4. Calcitonin from throid gland
  3. Steroids
    1. Cholesterol is the precursor for steroid hormones
      1. Adrenal cortex
        Cortisol + Aldosterone
      2. Ovaries
        Estrogen + Progesterone
      3. Testes
        Testerone
Regulation
1. Negative feedback mechanism
  1. Info about effects of hormone fed back to gland, decreasing secretion
2. Releasing hormones or (Releasing factors)
  1. Hormones of Anterior pituitary gland
    1. Secreted by Hypothalamus
  2. GHRH from Hypothalamus
    1. Secretes GH
3. Antagonistic pair
  1. regulate particular aspect of blood chemistry
Pituitary gland or (Hypophysis)
1. Posterior pittuitary (neuohypophysis)
  1. Extension of nerve tissue of hypothalamus
    1. and Anterior pituitary gland (Adenohypophysis)
  2. Oxytocin
    1. Stimulates release of milk from mammary glands when baby is nursing
    2. Stimulates contraction of the uterus at end of pregnancy
  3. (ADH or Vasopressin) Antidiuretic hormone
    1. Increases reabsorption of water by kidney tubules
      1. which decreases amount of urine formed
    2. Any type of dehydration stimulates secreation of ADH
      1. to conserve body warter
2. hangs by short stalk (infundibulum)
  1. Is enclosed by sella turcica of sphenoid bone
3. Anterior pituitary (Adenohypophysis)
  1. Releasing hormones are secreted into capillaries in hypthalamus
    1. Pass through Hypophyseal portal veins
      1. where RH stimulate secretion of
        Anterior pituitary hormones
  2. Growth hormone (GH) or Somatotropin
    1. Promotes growth indirectly
    2. Stimulates Cells to produce
      1. Chemicals (IGFs) Insulin-like growth factors
  3. Thyroid stimulating hormone (TSH) or Thyrotropin
    1. Target organ thyroid gland
    2. Stimulated by (TRH) Thyrotropin releasing hormone
      1. from Hypothalamus
      2. When metabolic rate (energy production) decreases
        TRH is produced
  4. (ACTH) Adrenocorticotropic hormone
    1. Stimulates secretion of cortisol and
      1. other hormones by adrenal cortex
    2. Secretion increased by (CRH) from hypothalamus
      1. (CRH) Corticotropin Releasing Hormone
        Produced by any type of physiological stress situation
        injury, disease, exercise or hypoglycemia
  5. Prolactin (PRL)
    1. Responsible for lactation
      1. Producing milk by mammary glands
        Regulation from hypothalamus involving
        (PRH) prolactin releasing hormone
        (PIH) prolactin inhibiting hormone
  6. (FSH) follicle stimulating hormone
    1. one of gonadotropic hormones
      1. has effects on the gonads, ovaries or testes
    2. Stimulates growth of ovarian follicles
      1. initiating egg development in cycles of approximately 28 days
    3. In men initiates sperm production within the testes
    4. in females stimulates secreation of estrogen by the follicle cells
    5. stimulated by hypothalamus
      1. producing (GnRH)
        gonadotropin releasing hormone
    6. FSH secretion decreased by
      1. Inhibin
        hormone produced by ovaries or testes
  7. (LH) Luteinizing Hormone
    1. Gonadotropic hormone
    2. Responsible for ovulation in women
    3. also called (ICSH)
      1. intersitial cell stimulating hormone
        In men secreates testerone in testes

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Endocrine System

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	Created by christopher467 over 11 years ago