BIOL251 Human Anatomy & Physiology I w/Lab
2026 | Module 6 Exam Review |70+ Actual
Questions and Answers Summary |LockDown
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Plus bonus 5pages exaplaing more about
Nervous System
Nerve tissue & the Nervous System
The human nervous system, by far the most complex system in the body, is formed
by a network of many billion nerve cells (neurons), all assisted by many more
supporting cells called glial cells. Each neuron has hundreds of interconnections with
other neurons, forming a very complex system for processing information and
generating responses.
Nerve tissue is distributed throughout the body as an integrated communications
network. Anatomically, the general organization of the nervous system has two major
divisions:
• Central nervous system (CNS),
consisting of the brain and spinal
cord.
• Peripheral nervous system (PNS),
composed of the cranial, spinal, and
peripheral nerves conducting
impulses to and from the CNS
(sensory and motor
nerves, respectively) and ganglia that
are small groups of nerve cells
outside the CNS.
Cells in both central and peripheral
nerve tissue are of two kinds:
1
, 1. Nerve cells or neurons, responsible for conduction, propagation, and
reception of nervous impulses. Processes called axons or dendrites extend
from these cells.
2. Glial cells, which have short processes, support and protect neurons, and
participate in many neural activities, neural nutrition, and defense of cells in
the CNS.
Neurons
The functional unit in both the CNS and PNS is the neuron or nerve cell. Some
neuronal components have special names, such as “neurolemma” for the cell
membrane. Most neurons consist of three main parts:
A) Cell body or Perikaryon: which contains the nucleus and most of the cell’s
organelles and serves as the synthetic or trophic center for the entire neuron:
(1) The nucleus is large, spherical, and pale staining and is centrally located in the
soma of most neurons. It contains abundant euchromatin and a large nucleolus.
(2) Cytoplasmic organelles and inclusions:
Nissl bodies are composed of polysomes and rough endoplasmic reticulum
(RER). They appear as clumps under light microscopy and are most abundant in
large motor neurons. Nissl bodies and free ribosomes extended into the dendrites
but not into the axon, this area of cell body called the axon hillock, which lacks
large cytoplasmic organelles.
The Golgi complex is near the nucleus, and mitochondria are scattered
throughout the cytoplasm.
(3) Cytoskeletal components:
Neurofilaments are abundant and run throughout the soma cytoplasm.
Microtubules are also present in the soma cytoplasm.
Microfilaments are associated with the plasma membrane.
B) Dendrites: which are the numerous elongated processes extending from the
perikaryon and specialized to receive stimuli from other neurons at unique sites called
synapses. Generally, dendrites are located in the vicinity of the cell body. They have
greater diameter than axons, are un-myelinated, are usually tapered, and form extensive
barbarizations called dendritic trees. Dendritic trees significantly increase the receptor
surface area of neuron. In general, the content of cytoplasm of the cell body and
2
, cytoplasm of dendrites are similar with the exception of the Golgi apparatus. Other
organelles characteristic of the cell body including ribosome and RER, are found in the
dendrite especially in the base of the dendrites.
C) Axon: which is a single long process ending at synapses specialized to generate
and conduct nerve impulses to other cells (nerve, muscle, and gland cells). Axons may
also receive information from other neurons, information that mainly modifies the
transmission of action potentials to those neurons. Axons originate from the axon
hillock, a specialized region of the cell body that lacks RER, ribosomes, Golgi
cisternae, and Nissl bodies but contains many microtubules and neurofilaments;
abundance of the latter may regulate neuron diameter. Further, it permits passage of
mitochondria and vesicles into the axon. A plasma membrane surrounding the axon is
called the axolemma. Axons terminate in many small branches from which impulses
are passed to another neuron or other types of cells.
3
2026 | Module 6 Exam Review |70+ Actual
Questions and Answers Summary |LockDown
Browser |Portage Learning
Plus bonus 5pages exaplaing more about
Nervous System
Nerve tissue & the Nervous System
The human nervous system, by far the most complex system in the body, is formed
by a network of many billion nerve cells (neurons), all assisted by many more
supporting cells called glial cells. Each neuron has hundreds of interconnections with
other neurons, forming a very complex system for processing information and
generating responses.
Nerve tissue is distributed throughout the body as an integrated communications
network. Anatomically, the general organization of the nervous system has two major
divisions:
• Central nervous system (CNS),
consisting of the brain and spinal
cord.
• Peripheral nervous system (PNS),
composed of the cranial, spinal, and
peripheral nerves conducting
impulses to and from the CNS
(sensory and motor
nerves, respectively) and ganglia that
are small groups of nerve cells
outside the CNS.
Cells in both central and peripheral
nerve tissue are of two kinds:
1
, 1. Nerve cells or neurons, responsible for conduction, propagation, and
reception of nervous impulses. Processes called axons or dendrites extend
from these cells.
2. Glial cells, which have short processes, support and protect neurons, and
participate in many neural activities, neural nutrition, and defense of cells in
the CNS.
Neurons
The functional unit in both the CNS and PNS is the neuron or nerve cell. Some
neuronal components have special names, such as “neurolemma” for the cell
membrane. Most neurons consist of three main parts:
A) Cell body or Perikaryon: which contains the nucleus and most of the cell’s
organelles and serves as the synthetic or trophic center for the entire neuron:
(1) The nucleus is large, spherical, and pale staining and is centrally located in the
soma of most neurons. It contains abundant euchromatin and a large nucleolus.
(2) Cytoplasmic organelles and inclusions:
Nissl bodies are composed of polysomes and rough endoplasmic reticulum
(RER). They appear as clumps under light microscopy and are most abundant in
large motor neurons. Nissl bodies and free ribosomes extended into the dendrites
but not into the axon, this area of cell body called the axon hillock, which lacks
large cytoplasmic organelles.
The Golgi complex is near the nucleus, and mitochondria are scattered
throughout the cytoplasm.
(3) Cytoskeletal components:
Neurofilaments are abundant and run throughout the soma cytoplasm.
Microtubules are also present in the soma cytoplasm.
Microfilaments are associated with the plasma membrane.
B) Dendrites: which are the numerous elongated processes extending from the
perikaryon and specialized to receive stimuli from other neurons at unique sites called
synapses. Generally, dendrites are located in the vicinity of the cell body. They have
greater diameter than axons, are un-myelinated, are usually tapered, and form extensive
barbarizations called dendritic trees. Dendritic trees significantly increase the receptor
surface area of neuron. In general, the content of cytoplasm of the cell body and
2
, cytoplasm of dendrites are similar with the exception of the Golgi apparatus. Other
organelles characteristic of the cell body including ribosome and RER, are found in the
dendrite especially in the base of the dendrites.
C) Axon: which is a single long process ending at synapses specialized to generate
and conduct nerve impulses to other cells (nerve, muscle, and gland cells). Axons may
also receive information from other neurons, information that mainly modifies the
transmission of action potentials to those neurons. Axons originate from the axon
hillock, a specialized region of the cell body that lacks RER, ribosomes, Golgi
cisternae, and Nissl bodies but contains many microtubules and neurofilaments;
abundance of the latter may regulate neuron diameter. Further, it permits passage of
mitochondria and vesicles into the axon. A plasma membrane surrounding the axon is
called the axolemma. Axons terminate in many small branches from which impulses
are passed to another neuron or other types of cells.
3
