Nervous System Overview and Organization
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Questions and Answers

Granule cells act as sensory neurons.

False (B)

The axon is usually branched distally into structures called synaptic knobs.

True (A)

Oligodendrocytes are a type of sensory neuron.

False (B)

Dendrites primarily function to receive signals from other neurons.

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

Microglia are responsible for protecting neurons and are a type of supporting cell.

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

The largest part of the brain is the cerebellum.

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

The gray matter in the brain is located in the cortex, while the white matter is found in the subcortex.

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

The thalamus is located in the anterior part of the brain.

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

The cerebellum is connected to the brain stem through the cerebellar peduncles.

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

The pineal gland is primarily located in the hypothalamus.

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

The Central Nervous System (CNS) consists solely of the brain.

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

The Peripheral Nervous System (PNS) is responsible for carrying sensory information to the CNS.

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

The Autonomic Nervous System (ANS) is involved in voluntary muscle contractions.

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

Neurons are characterized by their properties of excitability and conductivity.

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

Sensory receptors in the PNS provide information exclusively from the internal environment.

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

The sympathetic nervous system is a division of the Autonomic Nervous System.

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

Somatic nerves primarily affect glandular activity.

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

Bipolar neurons have two distinct processes extending from the cell body.

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

The brain stem consists of the midbrain, pons, and medulla oblongata.

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

The anterior surface of the midbrain features the medulla oblongata.

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

The thalamus is part of the diencephalon.

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

There are 31 pairs of cranial nerves that arise from the spinal cord.

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

The spinal cord ends at the L1 vertebral level.

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

The medulla oblongata features a median fissure, pyramids, and olive.

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

The gray matter in the spinal cord is arranged in an H-shaped configuration.

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

The superior and inferior colliculi are involved in visual and auditory reflexes, respectively.

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

The white matter is found in the center of the spinal cord, surrounding the gray matter.

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

The pons is located anterior to the medulla oblongata.

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

The sympathetic nervous system prepares the body for 'resting and digesting'.

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

Both the sympathetic and parasympathetic nervous systems can innervate the same target organs.

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

Preganglionic neurons of the sympathetic nervous system originate from the craniosacral region.

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

The parasympathetic nervous system increases heart rate and blood pressure.

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

Sympathetic chain ganglia are also known as paravertebral ganglia.

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

The sympathetic nervous system inhibits peristalsis and closes the sphincters.

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

Terminal ganglia are primarily responsible for the sympathetic nervous system's functions.

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

The spinal meninges consist of three layers: dura mater, arachnoid, and pia mater.

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

The subarachnoid space contains nerve fibers.

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

Ascending tracts are responsible for carrying motor information.

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

Efferent nerve fibers are also known as afferent fibers.

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

Cranial nerves are classified as sensory, motor, or mixed nerves.

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

There are 31 pairs of cranial nerves in the human body.

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

The cauda equina is formed by the inferiorly running spinal nerve roots.

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

Plexuses are formed by the posterior rami of spinal nerves.

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

Dorsal root ganglia contain motor neurons.

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

The autonomic nervous system is a voluntary motor system for muscle control.

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

Flashcards

Nervous System Organization

The nervous system is organized anatomically into the Central Nervous System (CNS) and the Peripheral Nervous System (PNS). Functionally, the PNS is divided into sensory (afferent) and motor (efferent) divisions, further divided into somatic and autonomic branches.

Central Nervous System (CNS)

The central processing unit of the nervous system, composed of the brain and spinal cord.

Peripheral Nervous System (PNS)

The network of nerves and ganglia that connect the CNS to the rest of the body, conveying sensory and motor information.

Afferent Division

The part of the PNS that transmits sensory information from receptors to the CNS.

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Efferent Division

The part of the PNS that carries signals from the CNS to effectors (muscles/glands).

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Somatic Nervous System

The part of the efferent division that controls voluntary movements of skeletal muscles.

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Autonomic Nervous System

The part of the efferent division that controls involuntary actions of smooth muscle, cardiac muscle, and glands.

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Neuron Properties

Neurons exhibit the properties of excitability, conductivity, and secretion.

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Neuron Cell Body Function

The cell body, or soma, is the neuron's control center, responsible for protein synthesis.

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Dendrite Function

Dendrites receive signals from other neurons or sensory cells.

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Axon Function

The axon transmits signals away from the cell body to other neurons, muscles, or glands.

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Neuron Types: Sensory/Motor/Interneuron

Neurons are broadly categorized as sensory (afferent), motor (efferent), or interneurons for specific roles in signal transmission within the nervous systems.

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Neuroglia Function

Neuroglia, or glial cells, support neurons, protect them, and aid in function.

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Cerebrum function

Largest part of the brain, responsible for higher-level functions like thoughts, memory, and voluntary movements.

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Cerebellum role

Coordinates voluntary movements, balance, and posture.

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Diencephalon parts

Part of the brain including thalamus (relay center), hypothalamus (body regulation), and epithalamus (pineal gland).

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Brain ventricles

Fluid-filled cavities within the brain; crucial for cerebrospinal fluid circulation.

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Meninges layers

Protective membranes surrounding the brain and spinal cord (dura mater, arachnoid mater, pia mater).

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Midbrain location

Located between the cerebrum and pons, inside the brainstem.

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Midbrain Structures

Consists of cerebral peduncles and colliculi (superior and inferior), which are important for visual and auditory reflexes.

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Pons location

Located above the medulla oblongata in the brainstem.

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Medulla oblongata shape

Cone-shaped structure at the bottom of the brainstem, continuing into the spinal cord.

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Medulla oblongata features

Contains the pyramids, olives, and a median fissure, vital for various functions, including controlling vital reflexes.

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Spinal cord origin

Spinal cord originates from the brainstem and extends to the first lumbar vertebra (L1).

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Spinal cord function - conduction

The spinal cord facilitates the transmission of nerve impulses between the brain and the body.

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Spinal cord function-reflexes

The spinal cord processes and coordinates simple reflexes without input from the brain.

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Spinal cord cross-section

Spinal cord's cross-section shows a central canal surrounded by gray matter forming an 'H' shape and white matter making up columns.

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Spinal nerves

31 pairs of nerves originating from the spinal cord itself.

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Sympathetic Nervous System

The division of the autonomic nervous system responsible for preparing the body for "fight or flight" responses.

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Parasympathetic Nervous System

The division of the autonomic nervous system that promotes "rest and digest" activities.

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What are the main functions of the sympathetic nervous system?

It increases heart rate, blood pressure, and airflow, constricts blood vessels, inhibits digestion, and closes sphincters.

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What are the main functions of the parasympathetic nervous system?

It slows heart rate, increases digestion, and opens sphincters.

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Sympathetic Pathway

Preganglionic neurons originate in the thoracolumbar spinal cord and synapse with postganglionic neurons in the sympathetic chain ganglia.

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Parasympathetic Pathway

Preganglionic neurons originate in the brainstem and sacral spinal cord and synapse with postganglionic neurons near or within target organs.

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What is the difference between sympathetic and parasympathetic pathways?

Sympathetic pathways use a chain of ganglia, while parasympathetic pathways have ganglia near or within the target organs.

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Dura mater

The outermost layer of the spinal meninges, a tough, fibrous membrane that surrounds the spinal cord and provides protection.

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Arachnoid

The middle layer of the spinal meninges, a delicate, web-like membrane that lies beneath the dura mater and contains the cerebrospinal fluid.

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Pia mater

The innermost layer of the spinal meninges, a thin, transparent membrane that directly adheres to the surface of the spinal cord.

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Epidural space

The space between the dura mater and the vertebral canal, containing fat and blood vessels.

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Subarachnoid space

The space between the arachnoid and pia mater, filled with cerebrospinal fluid (CSF) that cushions and protects the spinal cord.

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Ascending tracts

Bundles of nerve fibers that carry sensory information from the body to the brain.

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Descending tracts

Bundles of nerve fibers that carry motor commands from the brain to the body.

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Upper motor neurons

Neurons that originate in the brain and transmit motor commands through the spinal cord.

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Lower motor neurons

Neurons that originate in the spinal cord and directly innervate muscles, causing them to contract.

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Cauda equina

The bundle of nerve roots that extend from the end of the spinal cord, resembling a horse's tail.

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Study Notes

Nervous System Overview

  • The nervous system is responsible for coordinating sensory data and motor commands.
  • It's roughly 2.5% of body mass.
  • It's continuous with the spinal cord via the foramen magnum.
  • Covered by meninges.

Nervous System Organization

  • Anatomically:
    • Central nervous system (CNS): Brain and Spinal Cord
    • Peripheral nervous system (PNS): Nerves, ganglia, and sensory receptors
  • Functionally:
    • Sensory/Afferent division: Sensory receptors bring information from internal/external environments to the CNS; subdivided into somatic (skin, muscle, bone, & joints), visceral (thoracic & abdominopelvic organs), and special (eye, ear, nose, & tongue)
    • Motor/Efferent division: Carries motor commands from the CNS to effectors; subdivided into somatic nervous system (SNS) and autonomic nervous system (ANS)
      • Somatic nervous system (SNS): Voluntary contraction of skeletal muscles
      • Autonomic nervous system (ANS): Involuntary control of smooth & cardiac muscle & glands; subdivided into sympathetic and parasympathetic divisions.

Nervous Tissues - Neurons

  • Properties: Excitability, Conductivity, Secretion
  • Classification (Anatomically):
    • Unipolar/pseudounipolar
    • Bipolar
    • Multipolar
    • Anaxonic
  • Classification (Functionally):
    • Sensory neuron (afferent)
    • Motor neuron (efferent)
    • Interneurons
  • Structure of a Neuron:
    • Cell body (soma): Nucleus, organelles (Nissl bodies, RER, mitochondria, Golgi complex), inclusions (melanin, lipofuscin), and cytoskeleton (microtubules, neurofibrils); responsible for protein synthesis.
    • Dendrites: Short, branched cytoplasmic extensions; receive signals.
    • Axon: Long, cylindrical projection; sends signals; includes the axon hillock, axoplasm and axolemma with synaptic knobs at the end of terminal arborization
  • Neuroglia (Supporting Cells):
    • Function: Support and protect neurons
    • Types: Oligodendrocytes, Astrocytes, Microglia, Ependymal cells, Schwann cells, Satellite cells

Central Nervous System - Brain

  • General features:
    • ~2.5% body-mass
    • Continuous with the spinal cord at the foramen magnum
    • Covered by meninges
  • Parts: Cerebrum, Cerebellum, Diencephalon, Brainstem
  • Brain Cavities: Lateral ventricles, Interventricular foramina, Third ventricle, Cerebral aqueduct, Fourth ventricle.
  • Cross-section: Gray matter (cortex), White matter (subcortex)
  • Cranial meninges: Dura mater, Arachnoid mater, Pia mater
  • Lobes: Frontal, Parietal, Temporal, Occipital, Insula (frontal lobe has central sulcus)

Central Nervous System - Spinal Cord

  • Functions: Conduction, Integration, Reflexes
  • General features:
    • Arises from brainstem
    • Ends at L1
    • 31 pairs of spinal nerves
  • Cross section: Median sulcus, central canal, Gray matter (H-shaped with dorsal, lateral, and ventral horns), White matter (surrounding the gray matter in columns)

Central Nervous System - Spinal Tracts

  • Ascending tracts: Sensory information from spinal cord to brain, using first-, second-, and third-order neurons.
  • Descending tracts: Motor commands from brain to spinal cord, using upper and lower motor neurons; can be ipsilateral or contralateral as they decussate or don't.

Peripheral Nervous System

  • Nerves: Bundles of axons surrounded with connective tissues (endoneurium, perineurium, epineurium).
    • Myelinated or unmyelinated
    • Classification: Afferent/efferent, Somatic/visceral, General/specific
    • Types: Spinal nerves, Cranial nerves
  • Cranial Nerves: 12 pairs arising from the base of the brain, classified as sensory, motor, or mixed. Mnemonic to remember the cranial nerves exists
  • Spinal Nerves : 31 pairs, arising from the spinal cord.
  • Ganglia: Clusters of neuron cell bodies; include dorsal root ganglia, paravertebral ganglia, prevertebral ganglia, terminal ganglia.

Autonomic Nervous System (ANS)

  • General Features:
    • Controls involuntary functions (e.g., heart rate, digestion)
    • Involves two-neuron chain for most responses
    • Subdivided into sympathetic and parasympathetic divisions
  • Sympathetic: Prepares the body for energy-expenditure, "fight or flight" response, characterized by:
    • Thoracolumbar origin
    • Short preganglionic fibers, long postganglionic fibers
    • Ganglia near or along vertebral column
  • Parasympathetic: Conserves and restores body energy, "rest and digest" response, characterized by:
    • Craniosacral origin
    • Long preganglionic fibers, short postganglionic fibers
    • Ganglia are located near or on target organ

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Nervous System Notes PDF

Description

Explore the intricate details of the nervous system in this quiz, covering both its overall structure and functional divisions. Understand the roles of the central and peripheral nervous systems, and discover how sensory and motor commands are coordinated. Test your knowledge and deepen your understanding of this fundamental biological system.

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