Endocrine System Flashcards
Horomone
A chemical ligand or signal that travels a distance through the bloodstream in order to stimulate a response in target cells, tissues, or organs
4 Avenues of Cell Communication
- Gap Junctions
- Hormones
- Neurotransmitters
- Paracrines
Endocrine VS Nervous
Nervous
- communicates with neurotransmitters
- Localized effects
- stops when stimuli stops
- reacts within milliseconds
Endocrine
- communicates with hormones
- generalized widespread effect
- lingers after stimuli stops
- reacts slower to stimuli
Endocrine VS Exocrine
Endocrine
- Ductless
- secrete into bloodstream
- intracellular effects
- fenestrated capillaries
Exocrine
- ducts
- secrete out to epithelial surface
- extracellular
- no fenestrated capillaries
Steroid Hormones
Estrogen Testosterone Cortisol Aldosterone Vitamin D
Non-steroid Hormones
Amines ( Norepinepherine , epinephrine )
Proteins (PTH, GH, PRL)
Peptides (ADH,OT,TRH,SS,GnRH)
Glycoproteins (FSH,LH,TSH)
Intracellular Chemical Signals that AREN’T hormones
Autocrines, Paracrines, Pheromones, Neurohormone, Nuerotransmitter or neuromodulator
TRH (Thyrotropin-releasing hormone)
Released by: Hypothalamus
Effects: Promotes secretion of TSH (thyroid-stimulating hormone) AND PRL (prolactin)
GnRH (Gonadotropin-releasing hormone)
Released by: Hypothalamus
Effects: promotes secretion of follicle-stimulating hormone (FSH) and Luteinizing Hormone (LH)
Corticotropin-Releasing Hormone (CRH)
Released by: Hypothalamus
Effects: Promotes secretion of adrenocoritcotropic hormone (ACTH)
Growth Hormone Releasing Hormone (GHRH)
Released by: Hypothalamus
Effects: promotes secreting of growth hormone (GH)
Oxytocin (OT)
Released by: Posterior pituitary
Effects: labor contractions, milk release
Antidiuretic Hormone (ADH)
Released by: Posterior pituitary
Effects: water retention
How is secretion rate regulated ?
1) action of a substance other than a hormone on an endocrine gland (insulin production)
2) Neural control of endocrine (epinephrine)
3) Control of secretory activity of one endocrine gland by hormone or neurohormone (TRH->TSH->T3 & T4->TRH)
What regulates anterior pituitary secretions?
HYPOTHALAMUS
What controls posterior pituitary secretions?
NEUROENDOCRINE REFLEXES
Melatonin
Released by: Pineal Gland
Effects: Circadian Rhythm Control