Human Body Function HBF 102 - Sympathetic Nervous System II

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Questions and Answers

What effect does sympathetic stimulation have on ejaculation in males?

Reduces seminal fluid production

Inhibits erection (correct)

Increases penile blood flow

Promotes ejaculation (correct)

How does stimulation of the sympathetic nervous system affect gastrointestinal activity?

Increases secretion and motility

Stimulates digestive enzyme release

Has no effect on motility

Decreases secretion and motility (correct)

What happens to the blood vessels supplying the gastrointestinal tract during sympathetic stimulation?

Vasoconstriction occurs to redirect blood flow (correct)

Vasodilation occurs to increase blood flow

Blood flow remains unchanged

Blood flow decreases to improve digestion

In females, how does sympathetic stimulation affect the external genitalia?

Causes contraction or relaxation depending on hormone levels Signup and view all the answers

What long-term control mechanism is involved with norepinephrine (NE)?

NE is inactivated slowly Signup and view all the answers

What physiological response signals increased vasomotor tone during sympathetic activity?

Increased heart rate Signup and view all the answers

Which of the following is NOT a typical result of sympathetic nervous system activation?

Increased motility of the intestine Signup and view all the answers

What specific spinal cord segments are associated with the sympathetic division of the nervous system?

T1-L2 Signup and view all the answers

What is the outcome of sympathetic stimulation on blood glucose levels?

Increases blood glucose levels Signup and view all the answers

Which effect is associated with the contraction of smooth muscles in the male reproductive system during ejaculation?

Contraction of the vas deferens Signup and view all the answers

Which effect is NOT associated with sympathetic stimulation of the heart?

Decreased conductivity Signup and view all the answers

Which of the following reflects an effect of stimulation on cardiac function?

Increased heart rate and force of contraction Signup and view all the answers

What is the origin of the preganglionic fibers for the greater splanchnic nerve?

Lateral horn of lower thoracic segments Signup and view all the answers

In which of the following divisions does bronchodilatation occur during sympathetic nervous system activation?

Cardio-pulmonary division Signup and view all the answers

Which of the following is a function of the sympathetic nervous system in relation to the lungs?

Bronchodilatation Signup and view all the answers

What type of effect does sympathetic stimulation have on coronary blood vessels?

Increased constriction Signup and view all the answers

Which structures supply the thoracic viscera with postganglionic fibers?

Cardiac and pulmonary plexuses Signup and view all the answers

Which division is primarily responsible for innervating the abdominal viscera?

Splanchnic division Signup and view all the answers

What function does the greater splanchnic nerve NOT provide?

Control of heart rate Signup and view all the answers

What is the primary effect of sympathetic stimulation on the functions of smooth muscles in the bronchi?

Decrease in airway resistance Signup and view all the answers

What effect does the stimulation of the adrenal medulla primarily have on the circulatory system?

Triggers vasoconstriction of visceral blood vessels Signup and view all the answers

Which of the following correctly describes the effect on the gastrointestinal tract?

Relaxes the wall and contracts the sphincters Signup and view all the answers

During stress, which hormone is predominantly secreted by the adrenal medulla?

Epinephrine Signup and view all the answers

What is the primary effect of stimulation of the renal vessels?

Decreases renal blood flow Signup and view all the answers

What happens to the gall bladder upon stimulation?

Contracts to expel bile Signup and view all the answers

Which action is caused by stimulation of the smooth muscle of the splenic capsule during hemorrhage?

Contraction to release stored blood Signup and view all the answers

The lesser splanchnic nerve primarily affects which area of the body?

Pelvic viscera Signup and view all the answers

Which of the following statements about the effects of catecholamines is true?

The effects can be prolonged compared to direct sympathetic stimulation Signup and view all the answers

What is the effect on the urinary bladder when stimulated?

Relaxation of the bladder wall and contraction of the internal sphincter Signup and view all the answers

Which of the following describes the relationship between sympathetic nerve stimulation and catecholamine secretion?

Sympathetic stimulation directly causes catecholamine secretion Signup and view all the answers

Study Notes

Faculty of Medicine

Academic Year: 2024-2025
Year: 1
Semester: 1
Module: Human Body Function (HBF) 102

Sympathetic Nervous System - II

Lecturer(s): Dr. Maessa M. Elnhas (Professor of Physiology, Tanta University), Dr. Mohamed abo El Hassan (Professor of Physiology, Al-Azhar University)
Department: Clinical Physiology

Objectives

Describe the functions of sympathetic nerves on the thoracic part (heart and lungs).
Describe the organs supplied by the greater splanchnic nerve and their functions.
List the structures supplied by the lesser splanchnic nerve and discuss their functions.

Sympathetic Division

Preganglionic neurons are located in the lateral gray horn of T1-L2 segments of the spinal cord (thoracolumbar outflow).

Divisions of the Sympathetic Nervous System

Cervical
Cardio-pulmonary
Splanchnic
Somatic

Functions of Sympathetic Division

Heart: Stimulates all properties of cardiac muscle (increase rhythmicity, contractility, conductivity, and excitability). Positive inotropic effects = increased contractility, positive chronotropic effects = increased heart rate. Increased conductivity and excitability. Indirectly increases coronary blood vessel diameter due to increased cardiac metabolism. Direct effect is coronary vasoconstriction. Increases oxygen consumption of the heart.
Lungs: Relaxation of smooth muscles in bronchi and bronchioles (bronchodilation), decreased bronchial secretions. Constriction of pulmonary blood vessels preventing lung congestion.
Gastrointestinal Tract: Inhibition (relaxation) of wall and motor (contraction) of sphincters. Reduced gastric and intestinal secretions and motility. Vasoconstriction of stomach, small intestine, proximal colon, kidney, pancreas and liver arterioles.
Gall bladder: Relaxation of plain muscles of the wall but contraction of the sphincter of Oddi.
Liver: Stimulates glycogenolysis (increase blood glucose levels)
Spleen: Contraction of smooth muscles of the splenic capsule (especially during hemorrhage), aiding the squeezing of stored blood into circulation.
Pancreas: Reduces insulin hormone and pancreatic juice secretion.
Kidney: Vasoconstriction of renal vessels leading to decreased renal blood flow and urine output. Stimulates renin secretion
Adipose tissue: Promotes lipolysis
Adrenal medulla: Stimulates secretion of adrenaline (80%) and noradrenaline (20%) hormones. Supplied by preganglionic sympathetic fibers (greater splanchnic nerve). Circulating catecholamines have the same, but more prolonged, effects as direct sympathetic stimulation.

Structures Supplied by Sympathetic Divisions

Includes various structures throughout the body, including organs such as the heart, lungs, intestines, kidneys, and adrenal glands, along with blood vessels and glands associated with them.

2 - Cardio-Pulmonary Division (Thoracic Division)

Preganglionic fibres originate in the upper four thoracic segments, relaying in the cervical and upper four thoracic lateral ganglia.
Postganglionic fibres form the cardiac and pulmonary plexuses to supply thoracic viscera.

3 - Splanchnic Division

Greater splanchnic nerve: Preganglionic fibres arise from the lower 6 thoracic segments, forming the greater splanchnic nerve. They relay in coeliac and superior mesenteric collateral ganglia, and some preganglionic fibers reach the adrenal medulla directly. Postganglionic fibres reach abdominal viscera along their blood vessels.
Lesser splanchnic nerve: Preganglionic fibres originate in upper 3 lumbar segments. The fibres form the lesser splanchnic nerve. These fibers relay in inferior mesenteric (hypogastric) ganglia. Postganglionic fibres extend through blood vessels to supply the pelvic viscera.

Functions of Divisions

Urinary bladder: Relaxation to the wall and contraction to the internal urethral sphincter, aiding retention of urine.
Distal colon and rectum: Inhibitory action on the wall and motor action to the internal anal sphincter, promoting retention of feces.
External genitalia (males): Inhibition of erection (vasoconstriction of erectile tissue), and ejaculation of semen (contraction of vas deferens, prostate, and ejaculatory ducts).
External genitalia (females): Contraction or relaxation of female genital organs based on menstrual cycle stage and hormonal levels.

Summary

Vasoconstriction of blood vessels to the gastrointestinal tract.
Increased heart rate
Increased blood pressure
Inhibition of gastrointestinal secretion and motility.
Increased metabolism
Ejaculation of semen

Long-term Control

Norepinephrine (NE) is slowly inactivated
Adrenal medulla releases epinephrine (EP) and norepinephrine (NE) which act for longer periods.
Maintain vasomotor tone.

Interactive Questions

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Description

This quiz focuses on the functions and structure of the sympathetic nervous system, particularly as it relates to the thoracic region, including the heart and lungs. It covers the roles of the greater and lesser splanchnic nerves, as well as the preganglionic neuron locations within the spinal cord. Test your understanding of this fundamental aspect of physiology in the context of your first semester studies.