Sympathetic (Adrenergic) Receptors and Functions - Guyton Flashcards
Vasoconstriction
Constriction of blood vessels
- Skin, kidneys, GIT, heart, CNS
Alpha Receptor (α1)
Both the CNS and heart have autoregulatory mechanisms that is why they contain both adrenergic receptors.
Iris dilation
Dilator pupillae: pupil dilation (far vision)
Alpha Receptor (α1)
Intestinal relaxation
Relaxation of smooth muscle = ↓Gl motility, ↓GI secretions = ↓GI absorption
Alpha Receptor
Intestinal sphincter contraction
Sphincters: constriction - prevents movement of food (pyloric sphincter); prevents excretion of feces (internal anal sphincter)
Alpha Receptor (α1)
Pilomotor contraction
Pilomotor: moving or tending to cause movement of the hairs of the skin.
Alpha Receptor
Bladder sphincter contraction
IUS: Constriction of the sphincter -> prevents urine flow
Alpha Receptor
a1 (internal urethral sphincter)
Inhibits neurotransmitter release
(Specific receptor)
- Inhibits opening of Ca+ channels
- Hvperpolarization of the cell
Alpha Receptor (a2)
End result: no release of NE
Vasodilation
(Specific receptor)
Ciliaris muscle: relaxation of ciliaris muscle -› far vision
Beta Receptor (B2)
ß2 (ciliaris muscle)
Cardioacceleration
(Specific receptor)
↑BP
Beta Receptor (B1)
B1 (nodal system)
Increased myocardial strength
(Specific receptor)
Beta Receptor (B1)
Uterus relaxation
(Specific receptor)
Beta Receptor (B2)
Intestinal relaxation
(Specific receptor)
Relaxation of smooth muscle = ↓Gl motility, ↓GI secretions = ↓GI absorption
Beta Receptor (B2)
B2 (smooth muscle)
Bronchodilation
(Specific receptor)
Beta Receptor (B2)
Calorigenesis
(Specific receptor)
Beta Receptor (B2)
Glycogenolysis
(Specific receptor)
Liver
Stimulates glycogenolysis and gluconeogenesis = ↑glucose
Beta Receptor (B2)
Lipolysis
(Specific receptor)
Beta Receptor (B1)
Bladder wall relaxation
(Specific receptor)
Relaxation of the detrusor muscle of the bladder
Beta Receptor (B2)
Thermogenesis
(Specific receptor)
Beta Receptor (В3)
