Adrenal Medulla Flashcards
Adrenal medulla composed of
Composed of chromaffin cells that secrete catecholamines, and that form part of the sympathetic nervous system
Chromaffin cells are innervated by ________which connect to the reticular formation of the ________,
________, and _______
cholinergic preganglionic fibers which connect to the reticular formation of the medulla oblongata, pons, and hypothalamic centers
Adrenal cortex: salt hormone
aldosterone
Adrenal cortex: sweet hormone
cortisol, corticosterone
Adrenal cortex: sex hormone
DHEA, DHEA-S, Androstenedione
Synthesis of Catecholamines:
1. ______ from the diet is absorbed into the chromaffin cell and hydrolyzed to _____and decarboxylated to ______
Tyrosine from the diet is absorbed into the chromaffin cell and hydrolyzed to dopa and decarboxylated to dopamine
Synthesis of Catecholamines:
2. Dopamine is transported into _______and converted to _______
Dopamine is transported into granules and converted to norepinephrine
Synthesis of Catecholamines:
3. Norepinephrine can be released in to the ______and added with a _______ to
form epinephrine, then stored in granules until release from cell by ____________
Norepinephrine can be released in to the cytosol and added with a methyl group to form epinephrine, then stored in granules until release from cell by sympathetic stimulation
Effects of Catecholamines:
CVS
- Peripheral vasoconstriction
- Systemic vasodilation
- Increase in force and rate
of heart contraction - Piloerection
Effects of Catecholamines:
Respiratory system
Brief apnea following IV route due to inhibition of the respiratory center in medulla oblongata
Effects of Catecholamines:
Smooth muscles
1.SM constriction through a-receptor binding
2. SM relaxation via b-
receptor binding,
3. Urinary bladder relaxation and sphincter contraction causing urine retention
4. Decrease GIT motility
Effects of Catecholamines:
Metabolism
- Glycogenolysis,
- Increased insulin and glucagon function
- Increased ATP production
alpha 1 receptor: radial muscle iris
contraction
beta 2 receptor: ciliary muscle
relaxation (ciliary muscle)
beta 2 receptor: skeletal muscle
increased contractility, glycogenolysis, K+ uptake
alpha 2, beta 1: fat cells
decreased lipolysis; increased lipolysis
alpha 1, beta 1: Kidney (renin)
decreased secretion; increased secretion
sex organs, male: alpha 1
ejaculation
uterus: alpha1, beta 2
pregnant: contraction (alpha 1); relaxation (Beta 2)
Nonpregnant: relaxation (B2)
Red brown tumors that arise from chromaffin cells, which constantly or episodically secrete catecholamines
Pheochromocytoma
Rare, benign, and observed in dogs, cats, and horses
Pheochromocytoma
Pheochromocytoma:
Clinical Dx:
Tx:
Clinical Dx is hard unless suspected early
Dx: ultrasonography
Tx: adrenalectomy
