Chapter 7 Flashcards
Explain the four criteria that make a chemical signal a hormone.
1) secreted by a cell(s) into the blood for transport to a
2) distant target
3) where - at very low concentrations
4) it affects growth, development, homeostasis or metabolism
Explain what the cellular mechanism of action of a hormone is.
- Depends on binding to target cell receptors
- Initiates biochemical responses
(1) Rates of enzymatic reactions
(2) Transport of ions or molecules across cell membranes
(3) Gene expression and protein synthesis
List three chemical classes of hormones and give an example of each.
1) Peptide hormones –> made out of amino acids
ex: insulin + parathyroid hormone
2) Steroid hormones –> made from cholesterol
ex: estrogen, cortisol, androgens
3) Amino acid-derived (amine) hormones
catecholamine examples: epinephrine, norepinephrine, dopamine
thyroid examples: T4
Compare endocrine cells’ synthesis, storage, and release of peptide and steroid hormones.
Peptide:
- synthesis: made from mRNA
- storage: in vesicles
- release: exocytosis
Steroid:
- synthesis: derived from cholesterol
- storage: not stored
- release: simple diffusion
Compare the location of hormone receptors and the cellular mechanisms of action of peptide and steroid hormones.
Peptide:
- location of hormone receptors: cell membrane
- cellular mechanisms of action: Bind surface membrane receptors + Cellular response through signal transduction system
Steroid:
- location of hormone receptors: intracellular (nucleus or cytoplasm)
- cellular mechanisms of action:
Cytoplasmic or nuclear receptors stimulate genomic effects
vs.
Cell membrane receptors stimulate nongenomic responses
Compare the three main groups of amine hormones.
1) tryptophan –> produces melatonin (from pineal gland)
2) 2 tyrosine molecules –> thyroid hormones
- act like steroid hormones
3) 1 tyrosine –> catecholamine hormones
- act like peptide hormones
Describe the role of the nervous system in endocrine reflexes.
Many endocrine reflexes involve the nervous system
Neurohormones are secreted into the blood by neurons
Compare the structure and function of the anterior and posterior pituitaries.
posterior pituitary:
- structure: neural tissue
- function: stores hormones made in hypothalamus
- axon potential happens –> posterior pituitary secretes two peptide neurohormones –>
vasopressin (antidiuretic hormone, or ADH)
+ oxytocin
anterior pituitary:
- structure: True endocrine gland (epithelial tissue)
- function: Tropic hormones stimulate secretion of other hormones
- Regulated by hypothalamic hormones (neural hormones)
- Secretes 6 peptide hormones
List [full spellings and abbreviations] the six anterior pituitary hormones, the hormones that control their release, and their primary targets.
Prolactin (PRL)
- hormones that control their release: dopamine (inhibiting hormone)
- primary targets: mammary glands (controls milk production)
Thyrotropin (TSH)
- hormones that control their release: thyrotropin-releasing hormone (TRH)
- primary targets: thyroid hormones (amines)
Adrenocorticotropic hormone/Adrenocorticotropin (ACTH)
- hormones that control their release: corticotropin-releasing hormone (CRH)
- primary targets: controls hormone synthesis + secretion in the adrenal cortex (cortisol)
Growth hormone (GH)
- hormones that control their release: GHRH (dominant - releasing hormone) + somatostatin (SS - inhibiting hormone) –aka growth hormone-inhibiting hormone (GHIH)
- primary targets: metabolism + stimulates hormone production in the liver
Follicle-stimulating hormone (FSH)
- hormones that control their release: Gonadotropin-releasing hormone (GnRH)
- primary targets: ovaries
Luteinizing hormone (LH)
- hormones that control their release: Gonadotropin-releasing hormone (GnRH)
- primary targets: ovaries + testes
Compare long-loop negative feedback for anterior pituitary hormones to the negative feedback loops for insulin and parathyroid hormone.
Long-loop negative feedback:
- Peripheral endocrine gland produces hormone that suppresses secretion of anterior pituitary and hypothalamic trophic hormones
- Most dominant feedback mechanism
Short-loop negative feedback:
- Pituitary hormone suppresses hypothalamic trophic hormone production
- Secondary feedback mechanism
Ultra-short-loop negative feedback:
- Occurs in hypothalamus and pituitary
- Autocrine or paracrine signals to regulate secretion
Explain permissiveness, synergism, and functional antagonism as they apply to hormones.
Synergism:
- The effect of interacting hormones is more than additive
Permissiveness:
- A permissive hormone allows another hormone to exert its full effect
Antagonism:
- Antagonistic hormones have opposing effects
- One substance opposes the action of another
- Competitive inhibitors vs. functional antagonists
Name the three most common types of endocrine pathologies.
1) Hypersecretion
2) Hyposecretion
3) Receptor/Second Messenger Problems
Explain how negative feedback can be used to determine the location of a problem with one gland in a two- or three-gland pathway.
1) Primary pathology due to last endocrine gland in pathway
2) Secondary pathology due to pituitary gland
3) Tertiary pathology due to hypothalamus
