Endo 2

Cards (25)

  • Prostaglandins
    • Powerful substances found in a wide variety of body tissues
    • Produced in a tissue and diffuse only a short distance to act on cells in that tissue
    • Several class include: PGA, PGE, and PGF
    • Influence many body functions, including respiration, blood pressure, gastrointestinal secretions, and reproduction
  • Pituitary (Hypophysis) Gland
    • Location: Diencephalon
    • Pituitary gland: Two-lobed organ that secrets important hormones
  • Adenohypophysis (True gland)
    • Anterior lobe; made of glandular tissue
    • Synthesizes and secrets a number of hormones
  • Neurohypophysis (Storage area)
    • Posterior lobe; made of neural tissue
    • Receives, stores, and releases hormones from the hypothalamus
  • Six hormones of the anterior pituitary

    1. Growth hormone (GH)
    2. Prolactin (PRL)
    3. Thyroid-stimulating hormone (TSH)
    4. Adrenocorticotropic hormone (ACTH)
    5. Follicle-stimulating hormone (FSH)
    6. Luteinizing hormone (LH)
  • Anterior Pituitary
    • Trophic effects:
    1. High blood [hormone] causes target organ to hypertrophy.
    2. Low blood [hormone] causes target organ to atrophy.
  • TSH: Stimulates growth of the thyroid gland; also stimulates it to secrete thyroid hormone
  • ACTH: Stimulates growth of the adrenal cortex and stimulates it to secrete glucocorticoids (mainly cortisol)
  • FSH
    • Initiates growth of ovarian follicles each month in the ovary and stimulates one or more follicles to develop to the stage of maturity and ovulation
    • Stimulates estrogen secretion by developing follicles
    • Stimulates sperm production in the male
  • LH
    • Acts with FSH to stimulate estrogen secretion and follicle growth to maturity
    • Causes ovulation
    • Causes luteinization of the ruptured follicle and stimulates progesterone secretion by corpus luteum
    • Causes interstitial cells in the testes to secrete testosterone in the male
  • GH
    • Stimulates growth by accelerating protein anabolism
    • Accelerates fat catabolism and slows glucose catabolism
    • By slowing glucose catabolism, tends to increase blood glucose to higher than normal level (hyperglycemia)
  • PRL: Stimulates breast development during pregnancy and secretion of milk after the delivery of the baby
  • Hypothalamic Control of the Anterior Pituitary
    • Hormonal control rather than neural
    • Hypothalamus neurons synthesize releasing and inhibiting hormones
    • Hormones are transported to axon endings of median eminence
    • Hormones secreted into the hypothalamo-hypophyseal portal system regulate the secretions of the anterior pituitary
  • Hypothalamic Control of Posterior Pituitary
    • Hypothalamus neuron cell bodies produce:
    1. ADH: supraoptic nuclei
    2. Oxytocin: paraventricular nuclei.
    • Transported along the hypothalamo-hypophyseal tract
    • Stored in posterior pituitary
    • Release controlled by neuroendocrine reflexes.
  • Physiology of posterior Pituitary gland
    • Posterior pituitary hormones
    1. ADH also known as Vasopressin
    2. Oxytocin
    • These hormones are synthesized in the neuron cell bodies in the hypothalamus and packed in secretory vesicles with neurophysin (carrier protein)
    • Does not synthesize hormones
    • Consists of axon terminals of hypothalamic neurons
  • Hypothalamic-Pituitary Relationships: Posterior Lobe
    • The posterior lobe is a down growth of hypothalamic neural tissue
    • Has a neural connection with the hypothalamus (hypothalamic-hypophyseal tract)
  • Secretions of the posterior pituitary are controlled by nervous signals from hypothalamus
  • Synthesis of ADH
    •  ADH synthesized in the cell bodies of hypothalamic neurons(supraoptic nucleus)
    • ADH is stored in the posterior pituitary
  • Two types of receptors for ADH
    1. V1: Mediate vasoconstriction
    2. V2: Located in the principle cells in distal convoluted tubule and collecting ducts in the kidneys
  • The most important function of ADH is to conserve body water by reducing urine output
  • Osmotic pressure:
    • Osmoreceptors in the hypothalamus
    1. ↑Osmotic pressure = ↑ADH secretion
    2. ↓Osmotic pressure = ↓ADH secretion
  • Blood volume
    • Baroreceptor  in carotid artery and aortic arch, and Stretch receptors in left atrium
    1. ↑Blood pressure = ↓ADH secretion
    2. ↓Blood pressure = ↑ADH secretion
  • Synthesis of Oxytocin
    • Oxytocin is synthesized in the cell bodies of hypothalamic neurons(paraventricular nucleus)
    • Oxytocin is stored in the posterior pituitary
  • Function of oxytocin
    • Stimulates the pregnant uterus to contract
    • May initiate labor
    • Causes glandular cells of the breast to release milk into ducts
    • Enhances social bonding
  • Hypothalamus
    • Actual production of ADH and oxytocin occurs in the hypothalamus
    • After production in the hypothalamus, hormones pass along axons into the pituitary gland
    • The secretion and release of posterior pituitary hormones is controlled by nervous stimulation
    • The hypothalamus controls many body functions related to homeostasis (temperature, appetite, and thirst)