chapt10_Part_2_holes_lecture_animation_jwt.ppt

Neurological cells, also known as nerve cells or neuroglial cells, are the fundamental units of the nervous system, responsible for receiving, processing, and transmitting information throughout the body. They work collectively to regulate voluntary and involuntary actions, maintain body homeostasis, and enable complex functions such as memory, learning, and decision-making. Neurological cells are broadly classified into two major groups:

Neurons – the primary functional units of the nervous system that generate and conduct electrical impulses. Neurons consist of three parts:

Cell body (soma): Contains the nucleus and controls metabolic activities.

Dendrites: Receive incoming signals from other cells.

Axon: Transmits impulses to target cells, such as muscles, glands, or other neurons.
Types of neurons include:

Sensory (afferent) neurons: Carry information from sensory organs to the CNS.

Motor (efferent) neurons: Transmit signals from the CNS to muscles and glands.

Interneurons (association neurons): Connect neurons within the CNS and coordinate responses.

Neuroglial (Glial) Cells – supportive cells that protect, nourish, and maintain neurons. They do not transmit impulses but are essential for proper nervous system functioning. Types include:

Astrocytes: Provide structural and metabolic support, form the blood–brain barrier.

Oligodendrocytes (CNS) and Schwann cells (PNS): Produce myelin sheath for faster nerve conduction.

Microglia: Act as immune cells, removing debris and pathogens.

Ependymal cells: Line ventricles of the brain and spinal cord, helping circulate cerebrospinal fluid.

Together, neurons and glial cells ensure efficient communication within the nervous system, enabling the body to respond to internal and external stimuli effectively.

1. 1
Types of Neuroglial Cells
in the PNS
1) Schwann Cells
• Produce myelin found on peripheral myelinated
neurons
• Speed up neurotransmission
2) Satellite Cells
• Support clusters of neuron cell bodies (ganglia)

2. 2
Types of Neuroglial Cells
in the CNS
2) Astrocytes
• CNS
• Scar tissue
• Mop up excess ions, etc.
• Induce synapse formation
• Connect neurons to blood
vessels
3) Oligodendrocytes
• CNS
• Myelinating cell
4) Ependyma or ependymal
• CNS
• Ciliated
• Line central canal of spinal
cord
• Line ventricles of brain
1) Microglia
• CNS
• Phagocytic cell

3. 3
Types of Neuroglial Cells
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Microglial cell
Axon
Oligodendrocyte
Astrocyte
Capillary
Neuron
Myelin
sheath (cut)
Node of
Ranvier
Ependymal
cell
Fluid-filled cavity
of the brain or
spinal cord

4. 4
Regeneration of A Nerve Axon
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Axon
Site of injurySchwann cells
(a)
(b)
(c)
(d)
(e)
Changes
over time
Motor neuron
cell body
Former connection
reestablished
Schwann cells
proliferate
Schwann cells
degenerate
Proximal end of injured axon
regenerates into tube of sheath cells
Distal portion of
axon degenerates
Skeletal
muscle fiber
20

5. 5
10.5: The Synapse
• Nerve impulses pass
from neuron to neuron at
synapses, moving from a
pre-synaptic neuron to a
post-synaptic neuron.
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Dendrites
Impulse
Impulse
Impulse
Synaptic
cleft
Axon of
presynaptic
neuron
Cell body of
postsynaptic
neuron
Axon of
postsynaptic
neuron
Axon of
presynaptic
neuron

6. 6
Synaptic Transmission
• Neurotransmitters are
released when impulse
reaches synaptic knob
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Mitochondrion
Synaptic knob
(a)
Synaptic cleft
Neurotransmitter
Axon
Ca
+2
Presynaptic neuron
Direction of
nerve impulse
Synaptic
vesicles
Cell body or dendrite
of postsynaptic neuron
Synaptic
vesicle
Vesicle releasing
neurotransmitter
Axon
membrane
Polarized
membrane
Depolarized
membrane
Ca
+2
Ca
+2

7. 7
Animation:
Chemical Synapse
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Please note that due to differing
operating systems, some animations
will not appear until the presentation is
viewed in Presentation Mode (Slide
Show view). You may see blank slides
in the “Normal” or “Slide Sorter” views.
All animations will appear after viewing
in Presentation Mode and playing each
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the latest version of the Flash Player,
which is available at
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8. 8
10.6: Cell Membrane Potential
• A cell membrane is usually electrically charged, or
polarized, so that the inside of the membrane is negatively
charged with respect to the outside of the membrane (which is
then positively charged).
• This is as a result of unequal distribution of ions on the
inside and the outside of the membrane.

9. 9
Distribution of Ions
• Potassium (K
+
) ions are the major intracellular positive ions
(cations).
• Sodium (Na
+
) ions are the major extracellular positive ions
(cations).
• This distribution is largely created by the Sodium/Potassium
Pump (Na
+
/K
+
pump).
• This pump actively transports sodium ions out of the cell
and potassium ions into the cell.

10. 10
Resting Potential
• Resting Membrane Potential
(RMP):
• 70 mV difference from
inside to outside of cell
• It is a polarized
membrane
• Inside of cell is negative
relative to the outside of
the cell
• RMP = -70 mV
• Due to distribution of
ions inside vs. outside
• Na
+
/K
+
pump restores
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
AxonCell body
Low Na
+
Axon terminal
Low K
+
High K
+
High Na
+
(a)
+
+
–
–
+
+
–
–
+
+
–
+
–
–
+
–
+
–
+
–
+
–
+
–
+
–
+
–
+
–
+
–
+
–
+–
–70 mV
(b)
+
+
–
–
+
+
–
–
+
+
–
+
–
–
+
–
+
–
+
–
+
–
+–
+
–
+
–
+
–
+
–
–70 mV
Low Na
+
Low K
+ High K
+
High Na
+
Na
+
K
+
(c)
Pump
Impermeant
anions
25

11. 11
Local Potential Changes
• Caused by various stimuli:
• Temperature changes
• Light
• Pressure
• Environmental changes affect the membrane
potential by opening a gated ion channel
• Channels are 1) chemically gated, 2) voltage gated,
or 3) mechanically gated
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Gatelike mechanism Protein
(b) Channel open(a) Channel closed
Cell
membrane
Fatty acid
tail
Phosphate
head

12. 12
Local Potential Changes
• If membrane potential becomes more negative, it has
hyperpolarized
• If membrane potential becomes less negative, it has
depolarized
• Graded (or proportional) to intensity of stimulation reaching
threshold potential
• Reaching threshold potential results in a nerve impulse,
starting an action potential