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)
