Nervous System Function and Classification

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Questions and Answers

What type of action do the parasympathetic and sympathetic nervous systems exhibit?

They are synergistic.

Both are anabolic.

Both are catabolic.

They are antagonistic. (correct)

Which of the following best describes the origin of the parasympathetic nervous system?

Thoraco-lumber.

Sacral and thoracic.

Craniosacral. (correct)

Cervical and lumbar.

How do the ganglia of the sympathetic nervous system differ in location compared to those of the parasympathetic nervous system?

Sympathetic ganglia are located near the effector organs.

Sympathetic ganglia are close to the CNS. (correct)

Parasympathetic ganglia are found in the thoracic region.

Parasympathetic ganglia are located far from the CNS.

Which chemical transmitter is released by neurons of the sympathetic nervous system?

Catecholamines. Signup and view all the answers

What is the primary function of the sympathetic nervous system during stressful situations?

Facilitating fight or flight response. Signup and view all the answers

Which of the following accurately describes the length of fibers in the parasympathetic nervous system?

Long preganglionic and short postganglionic fibers. Signup and view all the answers

How many total sympathetic ganglia are there in the body?

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What is the primary function of the sensory nervous system?

Relay sensory signals from organs to the CNS Signup and view all the answers

In which area are collateral or prevertebral ganglia primarily located?

Abdomen and pelvis. Signup and view all the answers

Which subdivision of the motor nervous system is responsible for voluntary muscle control?

Somatic motor nervous system Signup and view all the answers

What type of nerve fibers are involved in the autonomic nervous system?

Cholinergic and adrenergic fibers Signup and view all the answers

What does the grey matter in the spinal cord primarily contain?

Soma of the neurons Signup and view all the answers

Which of the following accurately describes the function of the central nervous system?

Processes and integrates sensory information Signup and view all the answers

How many pairs of spinal nerves are part of the peripheral nervous system?

31 pairs Signup and view all the answers

What is contained within the central canal of the spinal cord?

Cerebrospinal fluid Signup and view all the answers

Which is NOT a part of the autonomic nervous system?

Somatic motor system Signup and view all the answers

What type of anti-cholinesterase inhibits the destruction of acetylcholine and is relevant in war gas poisoning?

Irreversible anti-cholinesterase Signup and view all the answers

Which of the following enzymes is responsible for converting tyrosine into DOPA?

Tyrosine hydroxylase Signup and view all the answers

What process initiates catecholamine release into synapses?

Stimulated permeability to Ca2+ Signup and view all the answers

Which statement correctly describes the reuptake process of catecholamines?

50-80% is reuptaken by adrenergic nerve endings by active transport. Signup and view all the answers

Which type of drug is atropine classified as?

Parasympatholytic Signup and view all the answers

What is the final product of nor-adrenaline conversion in the presence of N-methyltransferase?

Epinephrine Signup and view all the answers

Which of the following fibers release catecholamines?

Adrenergic fibers Signup and view all the answers

What is a common effect of parasympatholytic drugs?

Blockage of muscarinic receptors Signup and view all the answers

What effect does the vagus nerve have on the heart rate?

It decreases heart rate without affecting the force of contraction. Signup and view all the answers

Which function is NOT associated with the sacral division of the autonomic nervous system?

Bronchodilation leading to increased airflow. Signup and view all the answers

What is the role of the medulla oblongata in the autonomic nervous system?

It contains centers for cardiac, respiratory, and vasomotor functions. Signup and view all the answers

Which of the following is a function of the autonomic nervous system that leads to secretion?

Secretion of pancreatic and bile juices. Signup and view all the answers

What is controlled by the higher centers of the autonomic nervous system?

Complicated reflexes primarily through spinal cord interactions. Signup and view all the answers

Which area of the autonomic nervous system is responsible for gall bladder contraction?

Pelvic nerve from the sacral division. Signup and view all the answers

What kind of reflexes are managed by lower centers in the autonomic nervous system?

Involuntary and simple reflexes. Signup and view all the answers

Which function is NOT facilitated by the higher centers of the autonomic nervous system?

Control over simple reflexes. Signup and view all the answers

What is the primary function of the oculomotor nerve?

Constriction of the eye pupil Signup and view all the answers

Which of the following cranial nerves is involved in the secretion of saliva from the parotid gland?

Glossopharyngeal nerve (9th) Signup and view all the answers

What is the origin of the facial nerve?

Superior salivatory nucleus Signup and view all the answers

The glossopharyngeal nerve relays through which ganglion to innervate the parotid gland?

Otic ganglion Signup and view all the answers

What type of saliva secretion is primarily produced by the glossopharyngeal nerve?

Large volume and rich in enzymes Signup and view all the answers

Which cranial nerve is responsible for the contraction of the ciliary muscle?

Oculomotor nerve Signup and view all the answers

What is the function of the vagus nerve in relation to glandular secretions?

No significant role in secretion Signup and view all the answers

What is the role of the greater superficial petrosal nerve?

Regulation of lacrimal gland secretions Signup and view all the answers

Study Notes

Overview of the Nervous System

The nervous system (NS) regulates all body functions via sensory and motor signals.
Sensory signals travel from organs to the central nervous system (CNS) via afferent nerves.
Motor signals travel from the CNS to organs through efferent nerves.

Functional Classification

Sensory Nervous System: Transmits sensory signals from organs to the CNS using afferent nerve fibers.
Motor Nervous System: Delivers motor signals from the CNS to muscles and glands via efferent nerve fibers, divided into:
- Somatic Motor Nervous System: Controls voluntary functions and skeletal muscle.
- Autonomic Nervous System: Manages involuntary functions, controlling cardiac and smooth muscles and glands, split into:
  - Sympathetic Nervous System: Uses adrenergic fibers.
  - Parasympathetic Nervous System: Uses cholinergic fibers.

Anatomical Classification

Central Nervous System (CNS): Comprises the brain and spinal cord.
Peripheral Nervous System (PNS): Includes 12 cranial nerves (sensory, motor, mixed) and 31 pairs of mixed spinal nerves.

Spinal Cord Structure

Central Canal: Contains cerebrospinal fluid.
Grey Matter: Involves anterior, lateral, and posterior horns with neuronal soma.
- Lateral horn is present only in sympathetic nerves (T1-L2).
White Matter: Composed of nerve fibers with a myelin sheath, appearing white.

Characteristics of Autonomic Nervous Systems

Antagonistic Actions: Parasympathetic promotes energy storage; sympathetic promotes energy consumption.
Reciprocal Actions: One system's activation inhibits the other, except in specific situations (e.g., sexual activity).
Distribution:
- Parasympathetic NS has limited distribution (7 nerves), acting in isolation.
- Sympathetic NS has widespread distribution (15 nerves), acting as a cohesive unit.
Ganglia Location:
- Parasympathetic ganglia are distant from the CNS, with long preganglionic and short postganglionic fibers.
- Sympathetic ganglia are close to the CNS, leading to short preganglionic and long postganglionic fibers.
Origin: Parasympathetic is craniosacral; sympathetic is thoracolumbar.
Function:
- Parasympathetic maintains homeostasis at rest.
- Sympathetic maintains homeostasis during stress (fight or flight).
Neurotransmitters:
- Parasympathetic uses acetylcholine.
- Sympathetic releases catecholamines (epinephrine and norepinephrine).

Autonomic Ganglia

Definition: Collections of postganglionic neuronal cell bodies outside the CNS, versus nuclei inside the CNS.
Types of Sympathetic Ganglia:
- Lateral or Paravertebral Ganglia: 26 in total, forming a sympathetic chain.
- Collateral (Prevertebral) Ganglia: Located mid-way between the spinal cord and organs, unpaired.

Cranial Division of the Autonomic Nervous System

Oculomotor Nerve (III): Controls pupil constriction and lens accommodation.
Facial Nerve (VII): Innervates salivary and lacrimal glands for secretion and vasodilation.
Glossopharyngeal Nerve (IX): Regulates secretion of the parotid salivary gland.
Vagus Nerve (X): Manages heart rate, bronchial secretion, gastrointestinal motility, and bile secretion.
Sacral Division: Controls urination, defecation, and sexual arousal through pelvic nerves.

Centers Controlling Autonomic Nervous System

Lower Centers:
- Spinal cord and brainstem (medulla oblongata and pons) manage simple reflexes.
Higher Centers:
- Cerebral cortex regulates lower centers to modulate autonomic activities.

Pharmacology of the Autonomic Nervous System

Anti-cholinesterase Agents: Inhibit breakdown of acetylcholine; reversible agents used medically to enhance parasympathetic function.
Parasympatholytics: Block parasympathetic actions, e.g., atropine (muscarinic blocker) and curare (neuromuscular junction blocker).
Catecholamines Release: Initiated by action potentials, leading to synaptic vesicle exocytosis that releases neurotransmitters into synapses.
Inactivation of Catecholamines: Occurs via reuptake into adrenergic nerve endings or diffusion into body fluids.

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Description

Explore the intricacies of the nervous system in this quiz, focusing on its functional classification and the role of sensory and motor signals. Understand how the nervous system regulates both voluntary and involuntary functions across different body organs. Test your knowledge on the pathways and mechanisms that govern these critical processes.