Mammalian Endocrine System

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Mammalian Endocrine System
2013-04-26 08:37:53
BIO 220

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  1. Hypothalamus
    - Region of lower brain that receives information from peripheral nerves and other brain regions. It controls much of the endocrine system. It contains two types of neurosecretory cells that release hormones into blood.
  2. Two types of neurosecretory cells
    1) Those that produce hormones that are stored in posterior pituitary. 2) Those that produce releasing hormones that regulate the anterior pituitary.
  3. Pituitary gland
    An appendage at the base of the hypothalamus consisting of 2 lobes:
  4. Explain the pituitary gland components
    Posterior pituitary (neurohypophysis).Anterior pituitary (adenohypophysis).
  5. Posterior pituitary
    Arises from floor of hypothalamus during embryonic development.Stores and secretes 2 hormones:1) Oxytocin2) Vasopressin or Antidiuretic hormone (ADH)
  6. oxytocin
    Induces uterine muscle contraction during child birth.Stimulates milk ejection by breasts.- Necessary for human bonding.
  7. Vasopressin o rantidiuretic hormone

    -Stimulates water reabsorption by collecting ducts of the kidneys.

    -Stimulates vasoconstriction and increased blood pressure.

    -Increases paternal behavior and other bonding behaviors.
  8. Anterior pituitary arises from where?
    roof of the throat as an invagination of the pharynx, called Rathke's pouch
  9. Anterior pituitary is regulated by what?
    releasing hormones/ factors from the hypothalamus
  10. - Releasing hormones from the __(i.e., GHRH, PRH, TRH, GnRH and CRH) are secreted into a __ leading to the __. They stimulate release of __ (i.e., GH, PR, TSH, FSH/LH and ACTH).
    • hypothalamus
    • capillary network
    • anterior pituitary
    • anterior pituitary hormones
  11. Growth Hormone (GH)
    • Glycoprotein
    • -  Affects wide variety of tissue.
    • -Stimulates entire body growth and organ enlargement.
    • -Directly promotes growth of some tissue.
    • -  Indirectly promotes growth of other tissue by stimulating production of growth factors (e.g., somatomedins).
  12. Prolactin (PRL)
    • Glycoprotein
    • -  Structurally similar to GH although roles different.
    • -Stimulates mammary gland development and milk synthesis in mammals.
    • -  Suppresses menstrual cycle and ovulation
  13. Follicle-stimulating hormone (FSH)
    • Glycoprotein
    • -  A gonadotropic hormone, i.e., stimulates gonads.
    • -  In females, stimulates ovarian follicle growth and   maturation and their production of estrogen.
    • -  In males, necessary for spermatogenesis, because   stimulates Sertoli cells to nurture maturing sperm
  14. Luteinizing hormone
    • -Glycoprotein
    • -A gonadotropic hormone.
    • -In females, stimulates ovulation and corpus luteum to produce progesterone.
    • -  In males, necessary for spermatogenesis, because stimulates Leydig cells to produce testosterone
  15. thyroid stimulating hormone (TSH)
    • -Glycoprotein
    • -Tropic hormone that stimulates the thyroid gland to produce its thyroxine (T4 and T3).
  16. 6) Adrenocorticotropic hormone (ACTH):
    - Stimulates adrenal cortex to produce and secrete glucocorticoids (e.g., cortisol and cortisone).
  17. Melanocyte-stimulating hormone (MSH)
    • When present, simulates melanin synthesis by malanocytes causing darkening of the skin within 24 hours.
    • However, MSH not secreted in adult humans and function unknown.
  18. endorphin
    • -Peptide hormone
    • -Opiate (opioid)
    • -Body’s natural morphine…pain killer.
    • -Produces euphoria
  19. Thyroid gland
    • Produces T3 (triiodothyronine) and T4 (thyroxine) derived from   tyrosine.
    • -  T3 more active.
    • -  Thyroid hormones critical for regulating metabolism in mammals.
    • Hyperthyroidism causes high body temperature, sweating, weight loss,   irritability and high blood pressure.
    • -  Hypothyroidism causes cretinism in infants, and weight gain, lethargy   and cold-intolerance in adults.
  20. Thyroid Gland Pt 2
    • Goiter (enlarged thyroid) from dietary iodine deficiency.
    • Thyroxine controls metamorphosis in amphibians.
    • -  TSH from anterior pituitary ... cAMP...T4 and T3.
    • -  TSH regulated by TRH from hypothalamus.
    • -  High levels of T4 and T3 inhibit TSH.
    • -  Also produces hormone called calcitonin. 
  21. Calcitonin
    • Polypeptide hormone that lowers blood calcium levels.
  22. Parathyroid glands
    • On surface of thyroid gland.
    • -  Produce parathyroid hormone (PTH).
    • -  PTH stimulates Ca2+ uptake by kidneys and bone   resorption by osteoclasts to release Ca2+ into blood.
    • -  PTH antagonizes effect of calcitonin and needs vitamin D   to function.
  23. Pancreas
    • Islets of Langerhans:
    • -  Each islet has alpha cells and beta cells.
    • -  Alpha cells produces glucagon (peptide hormone)
    • -  Beta cells produce insulin (protein hormone).
    • -  Insulin and Glucagon work antagonistically to maintain   blood glucose levels near 90 mg/ml.
    • -  Glucose is the major energy source for cellular respiration   and a key source of carbon.
  24. insulin
    • )
    • Lowers blood sugar by stimulating glucose uptake by most cells of the
    • body.
    • 2) Slows glycogen breakdown and Inhibits conversion amino acids into sugar by
    • liver.
  25. glucagon
    • Glucagon:
    • 1) Increases blood sugar concentrations by stimulating the hydrolysis of glycogen and conversion of amino acids into sugar, in liver.
  26. Diabetes Mellitus
    • Caused by insulin deficiency or loss of response to insulin in target tissues.
  27. Type 1
    • Autoimmune
    • -  occurs in childhood
    • -  insulin dependent
    • -  insulin injections several times/day
  28. Type II
    • Adults over 40
    • -  insulin deficiency and/or decreased responsiveness
    • -  non-insulin dependent
    • -  exercise and diet
  29. The adrenal gland is made of __
    adrenal cortex and medulla
  30. Adrenal medulla
    • Medulla contains cells that produce catecholamine hormones (i.e., epinephrine and norepinephrine) from tyrosine.
    • - under control of acetylcholine
  31. Epinephrine
    Epinephrine:  stimulates release of blood sugar by liver and skeletal muscle, and fatty acids from fat.
  32. Epinephrine and norephinephrine together
    Epinephrine and Norepinephrine together: increase heart rate, stroke volume, shunt blood away from skin, gut and kidneys to skeletal muscle and heart and brain.
  33. Adrenal cortex: 
    __ types of __ hormones
    • 2
    • corticosteroids
    • glucocorticoids (cortisol)
    •   2)  mineralocorticoids
  34. Glucocorticoids
    • release regulated by ACTH
    •   -  promote glucose synthesis form proteins.
    •   -  immunosuppressive
  35. Mineralocorticoids
    • promotes salt and water retention by kidneys.
    •   -  release not under ACTH control
  36. Glucocorticoids are really __ 
    immunosuppresants. They will suppress your immune system. 
  37. If there’s a physiological marker, its __
    cortisol. If your cortisol levels are higher, you ARE more stressed
  38. What will the outer layer of the cortex do?
    • -Outer layer makes aldosterone (steroid)
    • Will stimulate sodium and indirectly water reabsorption by distal tubules
    • 1) retention of soidium ions and water by kidneys
    • 2) increases blood volume and blood pressure
  40. Effects of glucocorticoids
    • 1) proteins and fats broken down and converted to glucose, leading too increased blood glucose
    • 2) possible suppression of immune system
  41. Effects of epinephrine and norepinephrine
    • 1) glycogen broken down to glucose; increased blood glucose
    • 2) increased bp
    • 3) increased breathing rate
    • 4) increased metabolic rate
    • 5) change in blood flow patterns, leading to increased alertness and decreased digestive, excretory, and reproductive system activity