Synergistic and Permissive Effects

When two or more hormones work together to produce a particular result, their effects are said to be synergistic. These effects may be additive or complementary. The action of epinephrine and norepinephrine on the heart is a good example of an additive effect. Each of these hormones separately produces an increase in cardiac rate; acting together in the same concentrations, they stimulate an even greater increase in car-

Chapter Eleven diac rate. The synergistic action of FSH and testosterone is an example of a complementary effect; each hormone separately stimulates a different stage of spermatogenesis during puberty, so that both hormones together are needed at that time to complete sperm development. Likewise, the ability of mammary glands to produce and secrete milk requires the synergistic action of many hormones—estrogen, cortisol, prolactin, oxytocin, and others.

A hormone is said to have a permissive effect on the action of a second hormone when it enhances the responsiveness of a target organ to the second hormone or when it increases the activity of the second hormone. Prior exposure of the uterus to estrogen, for example, induces the formation of receptor proteins for progesterone, which improves the response of the uterus when it is subsequently exposed to progesterone. Estrogen thus has a permissive effect on the responsiveness of the uterus to progesterone. Glucocorticoids (a class of corticosteroids including cortisol) exert permissive effects on the actions of catecholamines (epinephrine and norepinephrine). When these permissive effects are not produced because of abnormally low glucocorticoids, the catecholamines will not be as effective as they are normally. One symptom of this condition may be an abnormally low blood pressure.

Vitamin D3 is a prehormone that must be modified by enzymes in the kidneys and liver, where two hydroxyl (OH-) groups are added to form the active hormone 1,25-dihydroxyvi-tamin D3. This hormone helps to raise blood calcium levels. Parathyroid hormone (PTH) has a permissive effect on the actions of vitamin D3 because it stimulates the production of the hydroxylating enzymes in the kidneys and liver. By this means, an increased secretion of PTH has a permissive effect on the ability of vitamin D3 to stimulate the intestinal absorption of calcium.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


Responses

  • tori gibson
    When two or more hormones are additive?
    6 years ago
  • lempi
    What is permissive effect?
    5 years ago
  • Rebekah
    Is progesterone permissive?
    6 years ago
  • mebrahtu
    How are estrogen and progesterone permissive?
    6 years ago
  • matti
    Why estrogen is said to have a permissive effect on progesterone?
    6 years ago
  • marmaduc baggins
    What hormones has a permissive effect on Vitamin D3?
    5 years ago
  • gladys
    Which body system affects synergistic?
    4 years ago
  • ceredic
    What are synergist, antagonist and permissive hormone interaction?
    4 years ago
  • Zuzanna Davidson
    Which hormones have synergistic effects?
    4 years ago
  • piia
    What is different sinergizm and permissive actio?
    3 years ago
  • mauri tallus
    Are estrogen and progesterone permissive or synergistic?
    2 years ago
  • fergus
    Is epinephrine and norepinephrine permissive or synergistic?
    2 years ago
  • Phillipp
    How epinephrine and norepinephrine are synergestic?
    2 years ago
  • adaldrida
    Are ovaries opposing, synergistic, permissive?
    1 year ago
  • Bryan
    What is permissive action of hormone?
    11 months ago
  • kerstin
    Is estrogen and progesterone are synergists?
    11 months ago
  • Layton
    What is additive hormonal interaction?
    9 months ago
  • cameron
    What is additive complementary hormonal interaction?
    9 months ago
  • Klaus
    Is the stomach opposing, synergistic or permissive?
    8 months ago
  • fiamma
    What is the synergistic of anatomy and phisiology of all organ system in the human body?
    5 months ago
  • mikko
    What is the difference between additive and complementary interaction in endocrinology?
    5 months ago
  • roxy stewart
    What is additive hormone action?
    5 months ago
  • Primo
    What is synergism in endocrinology?
    3 months ago
  • Ermias
    Which hormones have synergistic effect on other hormones?
    2 months ago
  • lucas
    What are synergic hormones?
    2 months ago
  • Aleksi
    What is synergistic effecton hormons?
    1 month ago
  • Justiina
    What are hormonal interactions?
    17 days ago

Post a comment