Nervous System Flashcards
the Nervous System mainly functions in THREE (3) WAYS
Sensory, Integrative, and Motor Function
What function allows you to perceive changes, inside and outside of the body, and feel sensations.
Sensory Function
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
detect internal stimuli, such as an increase in blood pressure, or external stimuli.
Sensory receptors
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
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
What type of sensory information arises from sensory receptors in the skin, skeletal muscles or joints
Somatic sensory information
What type of sensory information arises from sensory receptors in the blood vessel or internal organs.
Visceral sensory information
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
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
a tissue structure that responds to an efferent impulse.
Effector
an impulse that travels away from the central
nervous system
Efferent impulse
What are the two main subdivisions of the Nervous System based on structural classification?
CENTRAL NERVOUS SYSTEM (CNS) and PERIPHERAL NERVOUS SYTEM (PNS
It includes mainly the brain (contains about 85 billion neurons) and spinal cord (contains about 100 million neurons
Central nervous system
It consists of all nervous tissue outside the CNS.
Peripheral nervous system
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
The PNS is further subdivided into three (3)
Somatic Nervous System (SNS), Enteric Nervous System (ENS) and Autonomic Nervous System(ANS).
SOMATIC NERVOUS SYSTEM (SNS) (soma = body) consists of:
Sensory and motor neurons
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
Neurons that conduct impulses from the CNS to skeletal muscles
Motor neuron
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
Examples of activities of the ENS:
Enteric sensory neuron and enteric motor neuron
monitor chemical changes within the GIT & the stretching of its walls
Enteric sensory neurons
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
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
- General somatic afferent fibers
- General somatic efferent fibers
- General visceral afferent fibers
- 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.