Lesson 3: Cells of the Nervous System and Organization of Tissues

Question 1

Two(2) Principal Kinds of Cells are:

Answer 1

Neuroglia
Neurons

Question 2

are the “nerve glue” or the cells that support the neurons of the CNS.Their name originates from the idea of early histologists that they were the “glue” that held nervous tissue together

Answer 2

Neuroglia Cells / Supporting Cells

Question 3

Neuroglia Cells / Supporting Cells provides:

Answer 3

SPIN
Support
Protection
Insulation
Nutrition

Question 4

They are smaller but they greatly outnumber neurons, perhaps by as much as 5 to 25 times and they do not generate action potentials. They continue to divide throughout an individual’s lifetime.

Answer 4

Neuroglia Cells / Supporting Cells

Question 5

Six types of Neuroglia:

Answer 5

Found in CNS:

Astrocytes
Oligodendrocytes
Microglia
Ependymal Cells

Found in PNS:

Schwann Cells
Satellite Cells

Question 6

Type of Neuroglia:
- are star-shaped cells with many processes. The processes make contact with blood capillaries, neurons and the pia matter

Answer 6

Astrocytes (astro- = star; -cyte = cell)

Question 7

2 types of Astrocytes:

Answer 7

Protoplasmic Astrocytes
Fibrous Astrocytes

Question 8

Type of Astrocytes:
with many short branching processes (location:gray
matter)

Answer 8

Protoplasmic Astrocytes

Question 9

Type of Astrocytes:
with long unbranched processes (location: mainly
white matter)

Answer 9

Fibrous Astrocytes

Question 10

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.

Answer 10

Blood Brain Barrier - BBB

Question 11

A component of BBB:
- encircle the capillaries-secrete chemicals that maintain the permeability characteristics of the tight junctions

Answer 11

Astrocytes & astrocytic feet/processes

Question 12

A component of BBB:
- Pericytes cover the basal lamina of the endothelium and contribute to the structural integrity of the BBB.

Answer 12

The capillary basement membrane/basal lamina with embedded pericytes.

Question 13

A component of BBB:
- consists mainly of tight junctions that seal together the
endothelial cells of brain blood capillaries and a thick basement membrane that surrounds the capillaries.

Answer 13

The tight JUNCTION between the OVERLAPPING endothelial cells of the brain capillaries

Question 14

Type of Neuroglia:
- These resemble astrocytes but are smaller and contain fewer processes.
- Give support by forming semi-rigid connective tissue rows between neurons in the CNS
- Produce phospho-lipid for the myelin sheath around axons of neurons in the CNS - responsible for forming and maintaining the myelin sheath around CNS axons.

Answer 14

Oligodendrocytes - (oligo- = few; -dendro- = tree)

Question 15

Type of Neuroglia:
- These neuroglia are small cells with slender processes that give off numerous spinelike projections.
- Act as macrophages – they engulf & destroy microbes and cellular debris/act as macrophages formed during normal development of the nervous system and phagocytize microbes and damaged nervous tissue.

Answer 15

Microglia or Brain Macrophages or Microglial Cells

Question 16

Type of Neuroglia:
- are cuboidal to columnar cells arranged in a single layer that possess microvilli and cilia. 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).
- Form a continuous epithelial lining for the ventricles of the brain & the central canal of the spinal cord
- Assist in the formation & circulation of CSF in the ventricles of the brain & the central canal of the spinal cord

Answer 16

Ependymal Cells or Ependymocytes - (epen-= above; -dym- = garment)

Question 17

Type of Neuroglia:
- Form myelin sheath around axons of neurons of the peripheral nervous system
o myelinates a single axon
o A single Schwann cell can also enclose as many as 20 or
more unmyelinated axons (axons that lack a myelin
sheath)
- participate in axon regeneration, which is more easily
accomplished in the PNS than in the CNS.

Answer 17

Schwann Cells

Question 18

Type of Neuroglia:
- these flat cells surround the cell bodies of neurons of PNS ganglia
- Provides structural support,
- Regulate the exchanges of materials between neuronal cell bodies and interstitial fluid.

Answer 18

Satellite Cells

Question 19

• are the basic functional unit of the nervous system
• they are the primary cells of the nervous system.
• its primary function is the conduction of impulses from one part of the body to another.
• it has the ability to respond to a stimulus and convert it into action potential (electrical excitability).

Answer 19

Neurons or Nerve Cells

Question 20

The fuel source for neurons is predominantly…

Answer 20

Glucose

Question 21

responsible for most special functions of the nervous system like perception, rationalization, memory, muscle control and glandular secretion regulation.

Answer 21

Neurons

Question 22

• they are irreplaceable
• they are highly specialized cells, most have lost the ability to undergo mitotic divisions

Answer 22

Neurons

Question 23

Parts of Neuron:

Answer 23

Cell Body
Dendrite
Axon

Question 24

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

Answer 24

Cell Body

Question 25

- are clusters of rough Endoplasmic reticulum and free ribosomes. - are the site of protein synthesis in neurons and are used to substitute cellular components, as material for growth of neurons, and to restore damaged axons in the PNS.

Answer 25

Nissl bodies

Question 26

cytoskeleton; for cell shape and support

Answer 26

Neurofibril

Question 27

cytoskeleton; assist movement of material to and from the cell body and axon

Answer 27

Microtubules

Question 28

can be found in aging neurons that is the result of accumulated neuronal lysosomes associated with aging. Studies have identified that these yellow brown granules in the cytoplasm cause no harm to the neuron.

Answer 28

Lipofuscin

Question 29

- are short with often highly branching cytoplasmic extension, hence, the origin of the name. - their cytoplasm comprises Nissl bodies, mitochondria, and other organelles. - receives information/input from other neurons or sensory receptors & carry the information toward the neuron’s cell body; the receiving or input portions of a neuron

Answer 29

Dendrite - (DEN-drı¯ts little trees)

Question 30

- a long thin, cylindrical projection that joins the cell body at a cone-shaped elevation called axon hillock. The initial segment is nearest to the axon hillock. - contains mitochondria, microtubules, and neurofibrils. - proliferates nerve impulses towards another neuron or muscular or glandular tissue

Answer 30

Axon - (single= axis)

Question 31

Part of Axon: - cone-shaped elevation where cell body joins an axon; The part of the axon closest to the axon hillock is the initial segment.

Answer 31

Axon Hillock

Question 32

Part of Axon: - cytoplasm

Answer 32

Axoplasm

Question 33

Part of Axon: - plasma membrane surrounding the axoplasm

Answer 33

Axolemma

Question 34

Part of Axon: - side branches along the length of an axon, typically at a right angle to the axon

Answer 34

Axon Collateral

Question 35

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

Answer 35

Myelin Sheath

Question 36

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

Answer 36

Saltatory Conduction

Question 37

Part of Axon: - unmyelinated gaps between segments of the myelin sheath

Answer 37

Node of Ranvier

Question 38

Part of Axon: - fine processes where the axon/axon collaterals end

Answer 38

Axon Terminal or Axon Telodendria

Question 39

Part of Axon: - bulb-shaped structures at the tips of axon terminals

Answer 39

Synaptic End Bulbs

Question 40

Part of Axon: - membrane-enclosed sacs of the synaptic end bulbs which store neurotransmitters

Answer 40

Synaptic Vesicles

Question 41

Enumerate the Classifications of Neurons According to Structure:

Answer 41

Multipolar Neuron Bipolar Neuron Unipolar Neuron

Question 42

Classifications of Neurons According to Structure: - the most common. They have multiple dendrites and one axon

Answer 42

Multipolar Neuron

Question 43

Classifications of Neurons According to Structure: - have 2 distinct processes: one main dendrite and one axon arising from the cell body. These are very rare types of neurons

Answer 43

Bipolar Neuron

Question 44

Classifications of Neurons According to Structure: - are made up of only one projection from the cell body. These are very short neurons that divide into DISTAL (peripheral) and PROXIMAL (central) processes and only the most distal process acts as dendrites.

Answer 44

Unipolar Neuron

Question 45

Enumerate the Classifications of Neurons According to Function:

Answer 45

Sensory/Afferent Neurons Motor/Efferent Neurons Association/ Connecting Neurons/ Interneuron

Question 46

Classifications of Neurons According to Function: - either contain sensory receptors at their distal ends (dendrites) or are located after sensory receptors that are separate cells. They receive stimuli/info from either the internal or external environment thru the AFFERENT/SENSORY nerve pathways.

Answer 46

Sensory / Afferent Neurons

Question 47

Most sensory neurons are ________ in structure.

Answer 47

Unipolar

Question 48

Classifications of Neurons According to Function: - are structurally multipolar, carry impulses from the CNS to other parts of the body to effectors (muscles and glands) in the periphery through cranial or spinal nerves.

Answer 48

Motor / Efferent Neurons

Question 49

Classifications of Neurons According to Function: - that are also structurally multipolar, interprets/process the information received in order to determine appropriate response to take. Their axons extend only for a short distance and contact nearby neurons in the brain, spinal cord or in a ganglion.

Answer 49

Interneurons

Question 50

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

Answer 50

Nerve Fiber

Question 51

a bundle of many nerve fibers.

Answer 51

Nerve

Question 52

are cluster of cell bodies in the CNS.

Answer 52

Nuclei

Question 53

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

Answer 53

Ganglia

Question 54

a bundle of nerve fibers in the CNS.

Answer 54

Tract

Question 55

Enumerate Classifications of Layers of Nerve Fibers:

Answer 55

Endoneurium Perineurium Epineurium

Question 56

Classifications of Layers of Nerve Fibers: - surrounds an entire nerve

Answer 56

Epineurium

Question 57

Classifications of Layers of Nerve Fibers: - are thin connective tissue sheath that surrounds each nerve fiber/axon

Answer 57

Endoneurium

Question 58

Classifications of Layers of Nerve Fibers: - surrounds bundles of axons known as fascicles

Answer 58

Perineurium

Question 59

Group of Nerve Fibers: -

Question 60

Group of Nerve Fibers: - conduct nerve impulses from the skin, skeletal muscles and joints to the CNS

Answer 60

General somatic afferent fibers

Question 61

Group of Nerve Fibers: - conduct nerve impulses from the CNS to the skeletal muscles

Answer 61

General Somatic efferent fibers

Question 62

Group of Nerve Fibers: - convey nerve impulses from the viscera and blood vessels to the CNS

Answer 62

General Visceral Afferent Fibers

Question 63

Group of Nerve Fibers: - convey nerve impulses from the CNS to help contractions of smooth and cardiac muscles and rate of secretions of glands

Answer 63

General Visceral Efferent

Question 64

nerves carrying both sensory & motor impulses

Answer 64

Mixed Nerves

Question 65

nerves that carry impulses toward the CNS only

Answer 65

Afferent/Sensory Nerves

Question 65

nerves that convey impulses from the CNS only

Answer 65

Efferent/ Motor Nerves