Nervous System Overview

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Questions and Answers

What is the primary role of the efferent neuron in a reflex arc?

  • To detect the stimulus
  • To transmit signals to the CNS
  • To integrate the sensory input within the CNS
  • To carry the response from the CNS to the effector (correct)

Which division of the nervous system is primarily responsible for voluntary control of skeletal muscles?

  • Somatic nervous system (correct)
  • Visceral sensory division
  • Autonomic nervous system
  • Sympathetic nervous system

In a polysynaptic reflex, what is the main difference compared to a monosynaptic reflex?

  • Involves only one efferent neuron
  • Results in a slower reaction time
  • Transmits signals directly to the spinal cord
  • Involves multiple synapses with interneurons (correct)

What is the main function of synaptic clefts in the nervous system?

<p>To house neurotransmitters released by neurons (C)</p> Signup and view all the answers

What anatomical component is part of the peripheral nervous system?

<p>Peripheral nerves (D)</p> Signup and view all the answers

Which type of reflex is exemplified by the knee-jerk reflex?

<p>Monosynaptic reflex (B)</p> Signup and view all the answers

Which neurotransmitters are associated with the autonomic nervous system?

<p>Acetylcholine and Norepinephrine (B)</p> Signup and view all the answers

What type of fibers enter the spinal cord via the posterior root?

<p>Afferent fibers (D)</p> Signup and view all the answers

What is a consequence of a lesion on the cervical sympathetic chain associated with Horner's Syndrome?

<p>Constricted pupil on the affected side (C)</p> Signup and view all the answers

How does the sympathetic nervous system affect heart function?

<p>Increases electrical conduction and excitability (C)</p> Signup and view all the answers

What is the primary effect of the sympathetic response on the gastrointestinal tract?

<p>Enhanced contraction of the sphincters (D)</p> Signup and view all the answers

What is the effect of sympathetic stimulation on the pulmonary vessels?

<p>Mild vasoconstriction of pulmonary vessels (C)</p> Signup and view all the answers

Which cranial nerve is NOT primarily responsible for causing miosis in Horner's Syndrome?

<p>Optic nerve (B)</p> Signup and view all the answers

What physiological change occurs in the brain as a result of increased arterial blood pressure?

<p>Increased cerebral blood flow (C)</p> Signup and view all the answers

What is the role of the greater splanchnic nerve?

<p>It participates in gastrointestinal motility and visceral functions (B)</p> Signup and view all the answers

What is primarily regulated by the inferior cervical ganglia?

<p>Digestive processes (D)</p> Signup and view all the answers

Which ganglia are classified as sympathetic?

<p>Aorticorenal and celiac ganglia (D)</p> Signup and view all the answers

Which of the following accurately describes the function of parasympathetic ganglia?

<p>Stimulates digestion and induces relaxation (C)</p> Signup and view all the answers

What is the common term used to refer to the response regulated by sympathetic pathways?

<p>Fight or flight (D)</p> Signup and view all the answers

What effect does the sympathetic nervous system have on pupil diameter?

<p>Dilates the pupils (A)</p> Signup and view all the answers

Which of the following is NOT a function associated with the parasympathetic nervous system?

<p>Increasing heart rate (A)</p> Signup and view all the answers

How does the sympathetic nervous system primarily affect heart rate?

<p>Increases heart rate (C)</p> Signup and view all the answers

Which of the following ganglia are involved with the rest and digest functions?

<p>Otic and submaxillary ganglia (C)</p> Signup and view all the answers

Which response mechanism is associated with the gastrointestinal system being inhibited?

<p>Fight or flight response (C)</p> Signup and view all the answers

Which ganglia is associated with the stimulation of adrenaline release in response to stress?

<p>Celiac ganglia (D)</p> Signup and view all the answers

What describes the myelination of preganglionic fibers in the autonomic nervous system?

<p>They are myelinated and fast-conducting. (B)</p> Signup and view all the answers

Where are the cell bodies of postganglionic fibers located?

<p>In autonomic ganglia outside the CNS. (C)</p> Signup and view all the answers

What percentage of catecholamines secreted by the adrenal medulla is adrenaline?

<p>80% (B)</p> Signup and view all the answers

What characterizes the structure of the sympathetic chain ganglia?

<p>They are paired ganglia for each segment of the viscera. (B)</p> Signup and view all the answers

Which of the following ganglia is associated with longer fibers?

<p>Collateral ganglia. (C)</p> Signup and view all the answers

Which statement correctly describes the nature of postganglionic neurons in the adrenal medulla?

<p>They have lost their axons. (C)</p> Signup and view all the answers

What is a significant difference between catecholamine effects and sympathetic nerve effects?

<p>Catecholamine effects last 5 to 10 times longer than sympathetic effects. (D)</p> Signup and view all the answers

What is the primary function of postganglionic fibers?

<p>To transfer signals to target organs. (D)</p> Signup and view all the answers

From which segments of the spinal cord do sympathetic preganglionic neurons originate?

<p>All thoracic and upper two lumbar segments. (B)</p> Signup and view all the answers

Where do sympathetic postganglionic fibers originate?

<p>From autonomic ganglia related to major vessels. (C)</p> Signup and view all the answers

What is the general relationship between the number of postganglionic fibers and their corresponding preganglionic fibers?

<p>There are usually 8-9 postganglionic fibers for each preganglionic fiber. (A)</p> Signup and view all the answers

Which physiological response is NOT associated with the sympathetic nervous system's effect on the eye?

<p>Pupil constriction (miosis). (C)</p> Signup and view all the answers

Which of the following routes do preganglionic sympathetic fibers NOT take?

<p>Travel to the brain before synapsing. (A)</p> Signup and view all the answers

Which type of ganglia is primarily located midway between the spinal cord and the viscera?

<p>Paravertebral ganglia. (A)</p> Signup and view all the answers

What effect does the sympathetic nervous system have on the skin?

<p>Piloerection due to contraction of piloerector muscles. (B)</p> Signup and view all the answers

Which statement is true regarding the location of collateral ganglia?

<p>They are located along the abdominal aorta. (B)</p> Signup and view all the answers

Which of the following best describes the length of postganglionic fibers in the autonomic ganglia?

<p>They can range from 1 mm to several centimeters. (D)</p> Signup and view all the answers

Which function is primarily associated with the action of catecholamines in the body?

<p>Enhanced muscle contraction. (D)</p> Signup and view all the answers

What is the main role of the sympathetic nervous system in the salivary glands?

<p>Vasoconstriction of salivary glands. (A)</p> Signup and view all the answers

Flashcards

Nervous System

The body's communication network, responsible for receiving, processing, and responding to internal and external stimuli.

Reflex Arc

The basic functional unit of the nervous system, quickly responding to stimuli without conscious thought.

Neuron

The basic structural and functional unit of the nervous system, transmitting information.

Synapse

The junction between two neurons. Signals are transmitted chemically across a small space.

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Central Nervous System (CNS)

The brain and spinal cord; the main processing center of the nervous system.

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Peripheral Nervous System

The nerves outside the brain and spinal cord, connecting the CNS to the rest of the body.

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Sensory Neuron

Transmits information from receptors to the CNS.

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Motor Neuron

Transmits information from the CNS to effectors (muscles and glands).

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Sympathetic nervous system

Part of the autonomic nervous system that prepares the body for stress responses, like the fight-or-flight response.

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Parasympathetic nervous system

Part of the autonomic nervous system that controls the body's 'rest and digest' functions, like digestion and relaxation.

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Autonomic nervous system

Part of the nervous system that controls involuntary functions, such as heart rate and digestion.

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Target organs

Organs that receive signals from the autonomic nervous system.

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Ganglia

Clusters of nerve cell bodies outside the central nervous system.

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Fight-or-flight response

The body's physiological response to a perceived threat, accelerating heart rate and other associated functions.

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Rest-and-digest response

The process for calm and recovery that opposes the fight-or-flight response.

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Digestive processes

Metabolic processes that manage nutrients and their utilization.

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Heart rate

Speed of the heart's contractions.

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Pupil dilation

Increase of the opening in the eye's iris.

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Preganglionic Fiber

Myelinated nerve fiber carrying signals from the central nervous system to an autonomic ganglion.

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Postganglionic Fiber

Unmyelinated nerve fiber carrying signals from an autonomic ganglion to an effector organ.

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Autonomic Ganglion

Collection of nerve cell bodies outside the central nervous system where preganglionic and postganglionic neurons synapse in the autonomic nervous system.

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Sympathetic Chain Ganglia

Paravertebral ganglia located along the vertebral column, part of the sympathetic nervous system.

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Collateral Ganglia

Ganglia located near major abdominal arteries, part of the sympathetic nervous system.

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Terminal Ganglia

Ganglia located near or within an effector organ, part of the parasympathetic nervous system.

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Preganglionic-Postganglionic ratio

One preganglionic neuron synapses with 8-9 postganglionic neurons.

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Myelinated Fiber

A nerve fiber with a fatty insulation sheath called myelin, increasing speed of signal transmission.

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Unmyelinated Fiber

A nerve fiber without a myelin sheath; signal transmission is slower.

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Distribution Centers

Autonomic ganglia act as distributing points for nerve signals to various organs, directing the actions of the body.

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Adrenal Medulla Function

The adrenal medulla releases catecholamines (primarily adrenaline and noradrenaline) into the blood, mimicking the sympathetic nervous system's effects, but with a longer duration.

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Sympathetic Preganglionic Fibers

These fibers originate in the thoracic and upper lumbar spinal cord and travel to the sympathetic ganglia.

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Sympathetic Ganglia

These are clusters of neurons that relay signals from preganglionic to postganglionic fibers in the sympathetic nervous system.

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Postganglionic Neuron

The second neuron in the sympathetic pathway, releasing neurotransmitters directly onto target organs after receiving signals from a preganglionic neuron.

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Catecholamines

Neurotransmitters and hormones, including adrenaline (epinephrine) and noradrenaline (norepinephrine).

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Sympathetic Effect on Eye

Causes pupil dilation (mydriasis) and elevation of the eyelid.

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Sympathetic Pathway Branches

Preganglionic fibers either synapse in the same ganglion, another ganglion, or bypass the paravertebral ganglia to synapse in a collateral ganglion.

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Paravertebral Ganglia

Sympathetic ganglia running along the spinal column and connected to the spinal nerves.

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Sympathetic Effect on Skin

Causes vasoconstriction of blood vessels, hair erection, and sweating.

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Collateral Ganglion

Ganglia outside the paravertebral chain where preganglionic sympathetic neurons synapse with postganglionic fibers for specific organ systems.

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Horner's Syndrome cause

A lesion on one side of the cervical sympathetic chain.

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Horner's Syndrome symptom: Miosis

Pupil constriction on affected side

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Horner's Syndrome symptom: Ptosis

Drooping of the eyelid on affected side

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Thoracic Sympathetic Ganglia function

Regulates heart rate, force of contraction, and excitability; blood vessels in head/neck and bronchi.

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Greater Splanchnic Nerve Origin

Thoracic vertebrae (T5-T9) and connects to collateral ganglia.

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Sympathetic effect on GI

Relaxation of GI tract smooth muscles( except sphincters); stimulation of glycogenolysis in liver.

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Cerebral blood flow and vessels

Increased blood flow due to higher arterial pressure; mild vasoconstriction.

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Study Notes

Nervous System Overview

  • The nervous system receives information from internal and external environments.
  • Information is integrated (processed).
  • Integration occurs at three levels: spinal cord, lower brain (subcortical), and higher brain (cortical).
  • A rapid and precise response follows integration.

Anatomical Divisions

  • Central Nervous System (CNS): Includes the brain and spinal cord. It's the main processing center.
  • Peripheral Nervous System: Includes peripheral nerves and ganglia. It transmits signals between the CNS and the body.

Neuron Structure

  • Neuron: The basic structural unit of the nervous system.
  • Contains a cell body (with nucleus and organelles).
  • Dendrites: Receive impulses.
  • Axon (nerve fiber): Carries impulses away from the cell body. Can be myelinated (faster) or non-myelinated.
  • A nerve is formed of many nerve fibers (neurons).

Synapse

  • Synapse: Sites where axons of one neuron connect to dendrites, cell bodies, or axons of other neurons.
  • Synaptic cleft: The space between neurons where chemical transmitters are released.
  • Function: Transmission of impulse (electrical signal) from one neuron to another.

Physiological Divisions

  • Sensory Nervous System: Transmits information from peripheral receptors to the CNS (afferent fibers) through the posterior root.
  • Motor Nervous System: Transmits information from the CNS to effectors (muscles, glands etc.) (efferent fibers) through the anterior root.
  • Receptors: Receive external (light, sound, temperature) and internal (muscle tension, visceral) information.
  • Somatic Sensory Division: Receives information about the body surface (skin, muscles, joints) and special senses.
  • Visceral Sensory Division: Receives information from internal organs (viscera).
  • Autonomic Nervous System: Controls involuntary functions (e.g., smooth muscle, cardiac muscle, glands). Two branches: sympathetic and parasympathetic.
  • Somatic Nervous System: Controls voluntary actions (skeletal muscles)

Reflex Arc

  • Reflex: A functional unit of the nervous system.
  • Components:
    • Stimulus
    • Receptor (sensory organ where the impulse is initiated)
    • Afferent neuron
    • Center (one or more synapses in CNS)
    • Efferent neuron
    • Effector organ (the muscle or gland that performs the response)
    • Response
  • Types: Monosynaptic (simplest, one synapse) and polysynaptic (more complex, with interneurons).

Somatic Reflexes

  • Relay at dorsal horn cell or cranial nuclei
  • Afferent fibers: relay at dorsal horn cells or cranial nuclei
  • Efferent fibers: relay at lateral horn cells or cranial nuclei

Autonomic Reflexes

  • Origin: Anterior horn cells (AHCs) of spinal cord or Lateral horn cells(LHCs) or Cranial nuclei.

Autonomic Ganglia

  • Definition: A collection of neurons outside the central nervous system.
  • Types: Paravertebral (along the spinal column), Collateral (midway between spinal cord and organs), Terminal (near or within the target organ).
  • Function: Act as distribution centers.

Adrenal Medulla

  • Modified sympathetic ganglion.
  • Postganglionic neurons lose their axons.
  • Catecholamine secretion directly into blood (adrenaline/noradrenaline).
  • Effects are prolonged compared to other sympathetic effects.

Functions of Sympathetic Nervous System (Thoraco-lumbar)

  • Arise from thoracic and lumbar segments of the spinal cord.
  • Preganglionic fibers leave spinal cord via ventral roots.
  • Pass into ganglia of paravertebral sympathetic chain.
  • Course: one of 3 ways.
    • Synapse in the same ganglion.
    • Pass up or down the chain to another ganglion.
    • Pass through the chain without synapsing.

Head and Neck Functions

  • Eye: Control eyelid elevation, pupil dilation, and visual field.
  • Skin: Control vasoconstriction/vasodilation, hair erection, and sweat gland secretion.
  • Salivary glands: Control salivary secretion.
  • Cerebral circulation: Control cerebral blood flow.

Thorax Functions

  • Heart: Control heart rate, conduction, excitability, and contractility.
  • Lung: Control bronchodilation and mild pulmonary vessel control.

Abdomen Functions

  • Gastrointestinal Tract: Control relaxation of smooth muscle of the wall of the stomach, small intestine, and proximal part of the large intestine.
  • Liver: Control glycogenolysis (convert glycogen into glucose).
  • Spleen: Control contraction of the spleen capsule.
  • Other: Control secretion of adrenaline and noradrenaline into the blood, and vasodilation/vasoconstriction of blood vessels.

Pelvic Viscera Functions

  • GIT: Control of feces and rectum.
  • Urinary Bladder: Control of urine.
  • Male Genitalia: Control of ejaculation.
  • Female Genitalia: Varied effects according to menstrual cycle.

Metabolism and Blood Distribution

  • Metabolism: Sympathetic system effects on metabolism, including basal metabolism, blood glucose, clotting, and lipolysis..
  • Blood distribution: Sympathetic system activates "alarm" response.

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