Intro To Endocrines Flashcards
Endocrine gland
Ductless gland
Pours secretions directly into the circulation to affect the target cells
Glands with ducts
Exocrine glands
Pancreas exocrine and endocrine part
Exocrine- digestive enzymes (acinar cells)
Endocrine- insulin and glucagon (islets of langerhans)
Primary function of endocrine system
Produce hormones
Other functions of endocrine system
Preserve homeostasis of minerals, enzymes (enzyme reactions), vitamins, hormones (active status)
Reproduction, growth development
Regulate internal environment- water balance, ions, temp
Stimulates growth
Initiation of stress response
Metabolism
Gene expression
Protein synthesis
Neuroendocrine theory of aging
Altered biologic activity of hormones
Altered circulation levels of hormones
Altered secretory responses of endocrine glands
Altered metabolism of hormones
Loss of circadian control of hormone release
Aging and endocrine disorders
Diabetes mellitus
Hypothyroidism
Atypical endocrine cell damage
Genetically programmed cell change
Chronic wear and tear
Alterations in responsiveness of target organs
Loss of self regulation leading to disorders
Three types of hormones
Peptide/ protein hormones
Steroid hormones
Amino acid derived and amine hormones
Peptide/ protein hormones
Hydrophilic or lipophobic
Water soluble to allow easy transport into bloodstream
Synthesized in ER
Need surface receptor to pass across lipid based cell membrane
May need a second messenger system to modify protein
Examples- insulin parathyroid hormone
Steroid hormone
Derived from cholesterol (estradiol, androgens, cortisol, aldosterone)
Lipid soluble and can diffuse across the membrane
Move by diffusion, needs a protein carrier as not hydrophilic
Synthesized in adrenal cortex, and smooth ER
Examples- estrogen, androgen, cortisol
Amino acid derived and amine hormones
Some act like peptide hormones, and some like a steroid hormones
Peptide hormones
-Catecholamines (Neurotransmitters)
Steroid hormones
- Thyroid hormones (tyrosine)
Autocrine
Cells have receptors for their own secreted factors (itself)
liver regeneration
Paracrine
Cells respond to secretion of nearby cells (neighbor)
Healing wounds
Endocrine
Cells respond to factors (hormones) produced by distant cells
(Distant)
Hypothalamus
Highest level of endocrine control
Neural and hormonal pathways
Integrates the nervous and endocrine systems
How does the hypothalamus exert hormonal control?
Via hypothalamus pituitary axis
Releasing hormone stimulates synthesis, and secretion disorders
Inhibiting hormone’s prevent synthesis and secretion
How is the anterior lobe connected to the hypothalamus?
Through hypophyseal portal venous blood
How is the posterior lobe connected to the hypothalamus?
Axons descend from hypothalamus to the posterior lobe
Parathyroid and medullar adrenal
Not influenced by pituitary hormones
Not part of the hypothalamus pituitary axis
Anterior lobe/ adenohypophysis/ glandular tissue
Growth hormone/ somatotropin (peptide)
Thyroid stimulating hormone TSH (peptide)
Adrenocorticotropic hormone ACTH (peptide)
Prolactin PRL (peptide)
Gonadotropin FSH or LH (peptide)
Melanocyte stimulating hormone MSH (peptide)
Posterior lobe/ neurohypophysis nervous tissue
Supraoptic nucleus
Paraventricular nucleus
ADH (antidiuretic hormone/ vasopressin)
Oxytocin
- Uterine contractions and milk ejection from the breast
Positive and negative feedback regulation
Normal or increased activity of target glands (circulating hormones) have a negative feedback to the hypothalamus pituitary axis
- no releasing of factors, no hormone production
Diminished circulating hormones have a positive stimuli to hypothalamus to pituitary
- release factors for hormone production
Synergism
Combined effect is greater than the sum of individual effects
Permissiveness
Need a second hormone to get full effect
Antagonism
Functional antagonism ( one substance opposes the action of another)
Competitive inhibitors (compete for the same receptor)
Glucagon opposes insulin
Primary pathology due to what?
Issues with the last endocrine gland in pathway
Secondary pathology due to what?
Pituitary gland
Tertiary pathology due to what?
Hypothalamus
Metabolic clearance rate
Rate of disappearance of the hormone (concentration of the hormone)
Metabolic destruction by tissues are degradation by the target cells
- Degradation is mainly by enzymes found in the liver or kidney
- Binding with tissues
- Excretion by liver into bile
- Excretion by kidneys into the urine
Depends on half-life
Primary hypersecretion
Due to problem with adrenal cortex
CRH- low
ACTH- low
cortisol- high
Secondary hypersecretion
Due to pituitary problem
CRH- low
ACTH- high
Cortisol- high
Tertiary hypersecretion problem
Due to hypothalamic problem
CRH- high
ACTH- high
Cortisol- high
