Nervous System Flashcards by Charmaine Pascua

the Nervous System mainly functions in THREE (3) WAYS

Sensory, Integrative, and Motor Function

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What function allows you to perceive changes, inside and outside of the body, and feel sensations.

Sensory Function

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refers to receiving information about the environment, either what is happening outside (ie: heat from the sun) or inside the body (ie: heat from muscle activity).

Sensation or stimuli

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detect internal stimuli, such as an increase in blood pressure, or external stimuli.

Sensory receptors

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This information is then carried into the brain and spinal cord through cranial and spinal
nerves, to be exact the AFFERENT branch of the PNS.

Sensory information

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It integrates or processes sensory information by analyzing and storing some of it and by making decisions for appropriate responses to changes.

Integrative function or integration

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What type of sensory information arises from sensory receptors in the skin, skeletal muscles or joints

Somatic sensory information

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What type of sensory information arises from sensory receptors in the blood vessel or internal organs.

Visceral sensory information

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It carries out the response/s, processed by the Central Nervous System, to effector organs via the MOTOR (efferent) branch of the Peripheral Nervous System.

Motor function

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through the motor neurons, carry information from the brain toward the spinal cord and to the different parts of the body to carry out the command.

Motor function

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a tissue structure that responds to an efferent impulse.

Effector

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an impulse that travels away from the central
nervous system

Efferent impulse

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What are the two main subdivisions of the Nervous System based on structural classification?

CENTRAL NERVOUS SYSTEM (CNS) and PERIPHERAL NERVOUS SYTEM (PNS

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It includes mainly the brain (contains about 85 billion neurons) and spinal cord (contains about 100 million neurons

Central nervous system

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It consists of all nervous tissue outside the CNS.

Peripheral nervous system

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is composed of Cranial Nerves (the brain’s 12 pairs of nerves) & Spinal Nerves (31 pairs of nerves associated with the spinal cord) which serve as communication lines that carry impulses from the sensory receptors located on the different parts of the body to the CNS

Peripheral nervous system

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The PNS is further subdivided into three (3)

Somatic Nervous System (SNS), Enteric Nervous System (ENS) and Autonomic Nervous System(ANS).

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SOMATIC NERVOUS SYSTEM (SNS) (soma = body) consists of:

Sensory and motor neurons

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Neurons that carry information from somatic receptors in the head, body wall and limbs and from receptors from the special senses of vision, hearing, taste and smell

Sensory neuron

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Neurons that conduct impulses from the CNS to skeletal muscles

Motor neuron

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is also called the “Brain of the GUT”. Its operation is Involuntary and consists of neurons (100 million) in Enteric Plexuses that spread over the entire span of the GIT.

Enteric nervous system

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Examples of activities of the ENS:

Enteric sensory neuron and enteric motor neuron

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monitor chemical changes within the GIT & the stretching of its walls

Enteric sensory neurons

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govern contraction of the smooth muscles of the GIT, secretions of the GIT, such as acid from the stomach, and activities of GI tract endocrine cells, which secrete hormone

Enteric motor neurons

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The motor part of the ANS has two (2) branches

SYMPATHETIC NERVOUS SYTEM AND PARASYMPATHETIC NERVOUS SYSTEM.

is sometimes called the “FIGHT or FLIGHT” system, primarily increases ALERTNESS and prepares the body for QUICK response to certain situatio

Sympathetic nervous system

the “REST AND REPOSE” system / “REST-AND-DIGEST”. It primarily ACTS to CONSERVE ENERGY

PARASYMPATHETIC NERVOUS

Nervous tissue comprises two types of cells

neurons and neuroglia

provide most of the unique functions of the nervous system, such as sensing, thinking, remembering, controlling muscle activity, and regulating glandular secretions.

Neurons

smaller cells but they greatly outnumber neurons, perhaps by as much as 25 times.

Neuroglia

make up about half the volume of the CNS.

Neuroglia

Brain tumours derived from glia, called _ , tend to be highly malignant and to grow rapidly.

Gliomas

Four types of neuroglia found only in the CNS

astrocytes, oligodendrocytes, microglia, and ependymal cells

remaining two types of neuroglia present in the PNS

Schwann cells and satellite cells —

Neuroglia of the CNS can be classified on the basis of:

size, cytoplasmic processes, intracellular organisation

These star-shaped cells have many processes and are the largest and most numerous of the neuroglia.

Astrocyte

two types of astrocytes

Protoplasmic astrocytes and Fibrous astrocytes

A type of astrocyte that have many short branching processes and are found in grey matter

Protoplasmic astrocyte

have many long unbranched processes and are located mainly in white matter

Fibrous astrocytes

contain microfilaments that give them considerable strength, which enables them to support neurons.

Astrocyte

restricts the movement of substances between the blood and interstitial fluid of the CNS.

Blood brain barrier

consists of cellular structure that selectively inhibit certain substances in the blood from entering the interstitial spaces of the brain or CSF, thus making the nervous system impermeable to large & potentially harmful molecules.

Blood brain barrier

resemble astrocytes but are smaller and contain fewer processes.

Oligodendrocytes

responsible for forming and maintaining the myelin sheath around CNS axons.

Process of oligocendrocyte

multilayered lipid and protein covering around some axons that insulates them and increases the speed of nerve impulse conduction.

myelin sheath

These neuroglia are small cells with slender processes that give off numerous spinelike projections.

Microglial cells/microglia

they engulf & destroy microbes and cellular debris/act as macrophages formed during normal development of the nervous system and phagocytize microbes and damaged nervous Pssue.

Microglial cells/microglial

cuboidal to columnar cells arranged in a single layer that possess microvilli and cilia.

Ependymal cells

These cells line the ventricles of the brain and central canal of the spinal cord (spaces filled with cerebrospinal fluid, which protects and nourishes the brain and spinal cord).

Ependymal cells

two types of glial cells in the PNS

Schwann cells and satellite cells

These cells encircle PNS axons. Like oligodendrocytes, they form the myelin sheath around axons.

Schwann cells

single ___ myelinates several axons,

Oligodendrocyte

each ___ myelinates a single axon

Schwann cell

TRUE OR FALSE: Schwann cells participate in axon regeneration, which is more easily accomplished in the PNS than in the CNS.

True

flat cells surround the cell bodies of neurons of PNS ganglia

Satellite cells

Besides providing structural support, _____ regulate the exchanges of materials between neuronal cell bodies and interstitial fluid.

Satellite cells

axons surrounded by a multilayered lipid and protein covering, called the myelin sheath, are said to be ____

Myalinated

Substances may cross the BBB primarily by two mechanisms:

in between the endothelial cells or across the luminal membrane of the endothelial cell

The former is called _____, and the latter is _____.

paracellular transport, transcellular transport.

Transcellular transport occurs through _____ and _____.

passive and active mechanisms.

The FUEL SOURCE for neurons is predominantly_____

GLUCOSE

Give support by forming semi-rigid connective tissue rows between neurons in the CNS

Oligodendrocyte

The outer nucleated cytoplasmic layer of the Schwann cell, which encloses the myelin sheath, is the?

neurolemma (sheath of Schwann)

Gaps in the myelin sheath, called _____ appear at intervals along the axon.

nodes of Ranvier

composed primarily of myelinated axons.

White matter

contains neuronal cell bodies, dendrites, unmyelinated axons, axon terminals, and neuroglia.

Grey matter

the basic funcEonal unit of the nervous system

Neurons

What are the parts of a neuron

Cell cell body, dendrite, and Axon

The main portion of a neuron and contains a nucleus surrounded by cytoplasm where organelles such as lysosomes, mitochondria & Golgi complex are found.

Cell body

clusters of rough Endoplasmic reAculum and free ribosomes

Nissl bodies

clusters of rough Endoplasmic reAculum and free ribosomes

Nissle bodies

are the site of protein synthesis in neurons and are used to subsAtute cellular components, as material for growth of neurons, and to restore damaged axons in the PNS.

Nissl bodies

an electrical signal that propagates (travels) along the surface of the membrane of a neuron.

action potential

The cytoskeleton includes both

Neurofibrils and motor microtubules

composed of bundles of intermediate filaments that provide the cell shape and support,

Neurofibrils

assist in moving materials between the cell body and axon.

Microtubulues

can be found in aging neurons that is the result of accumulated neuronal lysosomes associated with aging.

Lipofuscin

Short with often highly branching cytoplasmic extension. The receiving or input portions of a neuron.

Dendrites

propagates nerve impulses towards another neuron, a muscle fibre, or a gland cell. A long, thin, cylindrical projection

Axon

axon contains:

mitochondria, microtubules, and neurofibrils.

a long, thin, cylindrical projection that often joins to the cell body at a cone-shaped elevation called the

Axon hillock

a long, thin, cylindrical projection that often joins to the cell body at a cone-shaped elevation called the

Axon hillock

The part of the axon closest to the axon hillock is the

Initial segment

The cytoplasm of an axon, called

Axoplasm

surrounded by a plasma membrane known as the

Axolemma

Along the length of an axon, side branches called

Axon collaterals

a multi-layered lipid and protein covering of an axon which insulates the axon and increases the speed of nerve impulse conduc-on. It is necessary for SALTATORY CONDUCTION.

Myelin Sheath

impulse propagation/transmission that skips from node to node, providing rapid transmission of impulses.

Saltatory Conduction

unmyelinated gaps between segments of the myelin sheath

Node of Ranvier

Fine processes where the axon/axon collaterals end

Axon terminal

bulb-shaped structures at the tips of axon terminals

Synaptic End Bulbs

membrane-enclosed sacs of the synaptic end bulbs which store neurotransmittera

Synaptic vesicles

Neurons are classified in two ways:

function and structure.

According to function, neurons can be:

sensory or afferent, motor or efferent and association or interneurons.

either contain sensory receptors at their distal ends (dendrites) or are located after sensory receptors that are separate cells.

Sensory neurons

Their axons extend only for a short distance and contact nearby neurons in the brain, spinal cord or in a ganglion.

Interneuron

carry impulses from the CNS to other parts of the body to e>ectors (muscles and glands) in the periphery through cranial or spinal nerves.

Motor/efferent neurons

According to structure, neurons can be:

unipolar, bipolar or multipolar neurons.

Interneurons and motor neurons are

Multipolar

Most sensory neurons are

Unipolar

Sensory neurons of the special senses are

Bipolar

universal term for any neuronal process (extension) whether dendrite or axon, that emerges from the cell body of a neuron.

Nerve fiber

bundle of many nerve fibers

Nerve

cluster of cell bodies in the CNS.

Nuclei

small groups of nervous tissue containing primarily of cell bodies which are found in the PNS.

Ganglia

bundle of nerve Vbers in the CNS.

Tract

What are the three connective tissue sheath

Endoneriums, Perineuriums, Epineurium

thin connective tissue sheath that surrounds each nerve fiber/axon

Endoneurium

surrounds bundles of axons known as fascicles

Perineurium

surrounds an antire nerve

Epineurium

GROUPS OF NERVE FIBERS ACCORDING TO FUNCTION

1. General somatic afferent fibers 2. General somatic efferent fibers 3. General visceral afferent fibers 4. General visceral efferent fibers

CLASSIFICATION OF NERVES ACCORDING TO THE DIRECTION IN WHICH THEY TRANSMIT IMPULSES

Mixed nerves, afferent/sensory nerves, efferent motor

Groups of nerve fibers can be classified according to?

function and direction of nerve impulse transmission.