histology - nervous tissue

neuron

structural and functional unit of the nervous system

Perikaryon

also known as the somatic cell or cell body

Perikaryon

tropic center (nutritive center) and the genetic center

Nucleus of neuron

Spherical or oval, large, pale staining, centrally located with a prominent nucleolus

Cytoplasm of neuron

Contains Nissl's granules, which are basophilic granules

Dendrites

short processes specialized in receiving stimuli from the environment, from the sensory epithelial cells or from other neurons

Dendrites

Nissl's granules extend into the _____

Axon

A long process, specialized in generating conduction nerve impulses to other cells (nerve, muscle or glands)

Axon hillock

axon starts as a short pyramidal initial segment called ____

Pseudounipolar

Single process close to the perikaryon

Pseudounipolar

Divides into 2 branches, forming a T-shape

cerebro-spinal ganglia and sensory ganglia

2 examples pseudounipolar neurons

Bipolar

has 2 processes

Bipolar

a single dendrite and a single axon

Multipolar

More than 2 processes

retina, spiral and vestibular ganglia of the inner ear and, olfactory mucosa

examples of bipolar neuron

multipolar

Motor neurons of CNS and peripheral autonomic ganglia.

sensory or afferent neurons

Involved in transmission of sensory stimuli from the environment or within the body

sensory or afferent neurons

impulse is transmitted to the CNS

motor or efferent neurons

Transmit impulses from the CNS to the effector organ (skeletal muscle) or from other efferent neurons that ultimately supply the effectors (smooth muscles, cardiac muscles, and glands)

interneurons

Associated neurons that transmit impulses from one part of the CNS to another

interneurons

Their processes do not leave the CNS

synapse

A contact area of one axon with the dendrites or perikaryon of another that posses polarity

telodendrion membrane, synaptic cleft, postsynaptic membrane

parts of synapse

neuroglial cells

also know as glial cells. They are the supporting cells of the CNS

neuroglial cells

does not synapse with other cells

H & E stain

what stain is used in neuroglial cells where only the nuclei are seen while the cytoplasm and processes are not visible

astrocytes, oligodendrocytes, microglia

types of neuroglial cells

astrocytes

Largest, most important supporting elements of the CNS

nucleus of astrocytes

Nucleus is spherical, centrally located and pale staining

protoplasmic astrocytes

Found in gray matter of the CNS. Abundant granular cytoplasm and processes have many branches but shorter and relatively thick

fibrous astrocytes

Found in white matter of the CNS. Cytoplasm shows fibrillar material and processes are long, slender and smooth that branch infrequently

ependymal cells

Supporting cells lining the central canal of spinal cord and ventricular cavities of the brain

ependymal cells

Cells are flattened to cuboidal to columnar shape with wide bases

ependymal cells

Surfaces are provided with cilia during embryonic life

nucleus of ependymal cells

Nuclei are elongated, round, or oval in shape

myelinated nerve fibers, glial cells

Medullary white matter is composed of ______

molecular layer, purkinje layer, granular layer

three layers of cortex of cerebellum

inner core of gray matter

Anterior or ventral horns and posterior or dorsal horns joined at the center by a thin gray matter called the central commissure, surrounding the central canal

outer core of white matter

Primarily composed of myelinated nerve fibers and neuroglial cells

nervous system

A group of tissues composed of highly specialized characteristics conductivity. cells of possessing excitability the and

brain, spinal cord

what comprises the CNS

cranial nerves, spinal nerves, autonomic nervous system

what comprises the PNS

somatic efferent

innervating somatic structures like skeletal muscles and skin

visceral efferent

innervating visceral or involuntary structures like smooth muscles, cardiac muscles and glands. This is the autonomic nervous system.

neurons

The active conducting elements

neuroglia

The supporting elements

neurons

Basic unit of the nervous system which conducts electrical impulses from one part of the body to another

dendrites

group of short, unsheathed processes arranged like branches of a tree that transmit impulses toward the cell body.

axon

a single, elongated sheathed process conducting impulses away from the cell body.

accessory cells

The non nervous elements consist of blood vessels, connective tissue, and supporting cells known collectively as neuroglia.

synapse

are points of connection between neurons. The axon of one neuron make functional contact with dendrites of another neuron

epinephrine, norepinephrine, acetylcholine

what are the main neurotransmitters

Acetylcholine

is released at neuromuscular junction.

action potential

A nerve impulse is a localized reversal in the charge of a cell membrane and spreads there like an electric current. This sudden electric change in the membrane called ____

myelin sheath

Insulating material covering axons in central and peripheral nervous system.

faster

the thicker the myelin sheath is, the faster or slower the passage of nerve impulse will be

saltatory conduction of impulses

the electrical impulse "jumps" from node to node in myelin sheath instead of traveling continuously along the nerve fiber

gray matter

so called because of its darker appearance and preponderance of nerve cell bodies.

white matter

composed chiefly of myelinated nerve fibers

Ganglion

also means cluster of nerve cell bodies and dendrites, but usually refers to those cells located outside the brain and spinal cord.

brain

part of the central nervous system within the skull

brain

most complex and largest mass of nervous tissue in the body and contains literally billions of nerve cells.

telencephalon

represents seven-eight of weight of brain

longitudinal fissure

runs from the posterior to the anterior aspects almost completely dividing it into 2 hemispheres.

corpus callosum

he hemispheres are connected in the midline by the _____ (largest band of crossing or commissural fibers). This is found in the depths of longitudinal fissure

lateral sylvian fissure

between the frontal and parietal lobes above and temporal lobe below.

central of sulcus (rolandic fissure)

Between frontal and parietal lobes

parieto-occipital fissure

between the occipital and parietal lobes.

calcarine fissure

found in the occipital lobe perpendicular to parieto occipital fissure around which is the visual center

frontal lobe

includes all the cortex lying anterior to the central sulcus Sylvius

frontal lobe

center for motor functions and personality

parietal lobe

lies posterior to central sulcus of Rolando and above lateral Sylvian fissure.

parietal lobe

center for ordinary sensory functions

temporal lobe

lies beneath the lateral sulcus of Sylvius

temporal lobe

center for hearing and olfaction

occipital lobe

occupies the posterior extremity of the cerebral hemisphere behind parieto-occipital fissure

insula (island of reil)

exposed when the lips of lateral Sylvian fissure are separated

primary motor area or pre-central gyrus

lies in the frontal lobe immediately anterior to the central sulcus

primary motor area or pre-central gyrus

Controls voluntary movements in the opposite side of the body

prefrontal area

concerned with behavior, character and emotional state of the individual.

prefrontal area

concerned with foresight, good judgment, abstract thinking.

Primary sensory/Somesthetic Area or Postcentral gyrus

lies behind the central sulcus of Rolando in parietal lobe

Primary sensory/Somesthetic Area or Postcentral gyrus

ordinary sensations of pain, temperature, pressure and touch, position and movement sensation from opposite side of body are received and interpreted here.

motor speech area

lies in inferior frontal gyrus of dominant hemisphere (usually the left)

motor speech area

broca’s area

sensory or speech area

lies in temporal lobes posterior to auditory area of dominant hemisphere

sensory or speech area

wernicke's area

Auditory or Hearing Area (transverse gyri of Heschl)

lies below lateral sulcus within the temporal lobe

Auditory or Hearing Area (transverse gyri of Heschl)

center for hearing

visual area

cortex around the calcarine fissure

visual area

found in occipital lobe

olfactory or smell area

within the temporal lobe

taste area

above lateral sulcus into the deep layers of the sensory area

diencephalon

located in the forebrain along with the cerebrum.

thalamus

Paired mass of gray matter situated below corpus callosum

vermis (Latin of worm)

the constricted central portion is called the _____ and the lateral expanded portions the hemispheres.

cerebellum

resembles the cerebrum in structure, with the gray matter forming a layer of cortex placed on the surface

cerebellum

greatly aids the motor cortex of the cerebral Hemispheres in the integration of voluntary movements.

pons

lies anterior to the cerebellum and between the midbrain and medulla