Sympathetic nervous system Flashcards
How does the SNS act in the eye?
In the eye, sympathetic activation causes the radial muscle of the iris (alpha-1) to contract which leads to mydriasis, allowing more light to enter. Furthermore, the ciliary muscle (beta-2) relaxes, allowing for far vision to improve.
How does the SNS act in the heart
In the heart (beta-1, beta-2), sympathetic activation causes an increased heart rate, force of contraction, and rate of conduction, allowing for increased cardiac output to supply the body with oxygenated blood.
How does the SNS act in the lungs?
In the lungs, bronchodilation (beta-2) and decreased pulmonary secretions (alpha-1, beta-2) occur to allow more airflow through the lungs.
How does the SNS act in the stomach and intestines
In the stomach and intestines, decreased motility (alpha-1, beta-2) and sphincter contraction (alpha-1), as well as contraction of the gallbladder (beta-2), occur to slow down digestion in order to divert energy to other parts of the body.
How does the SNS act in the pancreas?
The exocrine and endocrine pancreas (alpha-1, alpha-2) decreases both enzyme and insulin secretion.
How does the SNS act in the bladder
In the urinary bladder, there is relaxation of the detrusor muscle and contraction of the urethral sphincter (beta-22) to help stop urine output during sympathetic activation.
How does the SNS act in the kidney
The kidney (beta-1) increases renin secretion to increase intravascular volume.
How does the SNS act in the salivary glands
The salivary glands (alpha-1, beta-2) work through small volume potassium and water secretion.
How does the SNS act in the liver
In the liver, increased glycogenolysis and gluconeogenesis (alpha-1, beta-2) occur to allow for glucose to be available for energy throughout the body.
How does the SNS act in the spleen
In the spleen, there is contraction (alpha-1).
How does the SNS act in the adrenal medulla
the adrenal medulla (nicotinic receptor) increases the release of epinephrine and norepinephrine to act elsewhere in the body
How does the SNS act in the sweat glands
Sweat glands and arrector pili muscles (muscarinic) work to increase sweating and erection of hair to help cool down the body.
Symptoms of sympathetic activation
hypertension, tachycardia/palpitations, hyperglycemia, and diaphoresis.
SNS in the penis?
Erections are a product of parasympathetic activity. At resting state, the SNS predominates, and the penis remains flaccid.
