Physiological Effects of the Sympathetic Nervous System

Question 1

what are the physiological effects of the sympathetic NS on the heart?

Answer 1

-NA increases: increases rate of contraction, force of contraction and rate of relaxation

Question 2

what is the effect of the sympathetic NS on the blood vessels?

Answer 2

• NA/Adr inreses: produce vascular SM contractions so arteries narrow
• exeption: arteries of coronary and SKM relax
• bladder, uterus,GI SM relaxes
• airway SM relaxes

Question 3

what are the sympathetic effects on the kidneys?

Answer 3

• Juxta Glomerulus Apparatus (GPA) has increased number of sympathetic nerves and is located between the efferent and afferent arteries
• when nerves stem, causes the release of renin
• renin convert angiotensinogen to angiotensin I
• angiotensin I is a potent vasoconstrictor which increases the volume of blood

Question 4

what are sympathetic effects on the liver and SKM?

Answer 4

• increase in glycogenolysis and lipolysis

- nerves target phosphorylase and lipase

Question 5

what does the stimulation of sympathetic nerves do on the eyes?

Answer 5

• contracts the radial muscle of the eyes which widens the pupils
• also increases aqueous humour production

Question 6

what does the stimulation of sympathetic nerves do on sweat and hair?

Answer 6

• causes piloerection

- increases sweat production but is mediated by Ach not NA