Chapter 16 (Lecture) Flashcards
2 major controlling systems of the body
nervous and endocrine system
differences between the nervous system and the endocrine system
nervous system acts very quickly to effect change
endocrine system works slowly
the nervous system and endocrine system are ________________ on one another for the regulation of bodily functions
interdependent
a chemical messenger produced in minute amounts by a collection of specialized epithelial cells and is secreted directly into the blood or extracellular fluid, and acts on specific tissues called target cells
hormones
from simple amino acids to complex proteins (AA, peptides, glycoproteins); thyroid, epinephrine, norepinephrine [small AA], insulin and glucagon [more complex protein hormones]
amino acid derivative hormones
- synthesized from cholesterol
- primary ones are sex hormones and adrenal cortex hormones
steroid hormones
- not “true hormones”
- leukotrienes and prostaglandins
- autocrine or paracrine substances
- synthesized from arachidonic acid
eicosanoids
the hormones or chemical signals that act as ligands and bind to the receptors present on the cells producing them
autocrine substances
a substance secreted by a cell and acting on adjacent cells
paracrine substance
how do hormones work
- bind with receptors at their targets
- only alter or influence activities of cells
- have different effects on different targets (antagonism)
what are typical cell responses to hormonal stimuli (6)
*opening or closing of ion channels
* stimulate enzyme synthesis within cells
* activates or deactivates enzymes within the cell
* can cause phosphorylation of enzymes within the cell
* mRNA synthesis and direct gene activation
* can influence or affect mitosis
what are the types of hormone receptors
- amino-acid based second messenger systems
- intracellular receptors
which type of hormone receptor is most common
amino acid-based second messenger systems
membrane proteins that span the lipid bilayer
integral proteins
membrane proteins found on the inner or outer surfaces
peripheral proteins
act mainly as cell identifiers
glycoproteins
connected via blood vessels to the hypothalamus
anterior pituitary gland
first step of the hypophyseal portal system
when appropriately stimulated, hypothalamic neurons secrete releasing and inhibiting hormones into the primary capillary plexus
second step of the hypophyseal portal system
hypothalamic hormones travel through the portal veins to the anterior pituitary where they stimulate or inhibit release of hormones from the anterior pituitary
third and final step of the hypophyseal portal system
anterior pituitary hormones are secreted into the secondary capillary plexus
a harmful (in most cases) mechanism in which any deviation from the set point is amplified (ex: childbirth)
positive feedback
a homeostatic mechanism in which the variable oscillates around some set.point, in which deviation is resisted or diminished
negative feedback
types of regulation of hormonal secretion
- humoral stimulus
- neural stimulus
- hormonal stimulus
capillary blood contains low concentration of calcium which stimulates secretion of parathyroid hormone (PTH) by parathyroid glands
humoral stimulus