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Chapter 9
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Homunculus: This is how your brain perceives your body
I. Central Nervous System ( CNS )
Brain and Spinal Cord protected by the skull and vertebrae
II. Peripheral Nervous System ( PNS )
12 pairs of Cranial Nerves from the brain
31 pairs of Spinal Nerves from the spinal cord
Two Divisions
1. Somatic Nervous system ( SNS )
2. Autonomic or Visceral Nervous System (ANS )
a. Sympathetic - Speed things up
b. Parasympathetic – Slows things down
Figure 09.02
Figure 09.03
Nervous System Cells
Neurons: Cells that carry impulses
from one point to another and store
information
Neuroglia or Glial Cells – Involved
in metabolic and structural support
for neurons
Four Types are:
Astrocytes: Connect blood vessels
and neurons form Blood Brain
Barrier (BBB), Form Pial Glial
Layer a protective layer along the
CNS
Oligodendrocytes: Produce myelin
covering for neurons in the CNS
Microglia: Very small until activated
by an injury then work as a
phagocytes.
Alzheimer’s produces a lot of
microglia
Ependymal Cells – Line canals and
produce cerebrospinal fluid (CSF)
Figure 09.01
Neurons
Neurons with short axons
in the CNS can reproduce
in adults
Olfactory nerve cells for
smell can reproduce every
40 days
Nisal Substance
This is Endoplasmic
Reticulum involved in
protein synthesis
Axon Hillock
Figure 09.04
Figure 09.05
Figure 09.06
Types of Neurons
Myelinated –
Multipolar: Most common type of
neuron. Efferent or motor neuron
from CNS to Muscle or Gland
Pseudo-unipolar: Afferent or
sensory neurons from Receptors
to CNS
Unmyelinated –
Bipolar – neurons for connections
found in retina, olfactory
epithelium and auditory ganglia
and CNS
A group of neurons with the same
function inside the CNS are
called a Nucleus or Nuclei
Pseudo-
Outside the CNS they are called a
Ganglion or Ganglia
Figure 09.07
Figure 09.08
Synapse –
small space between neurons
very important for the
control and coordination of
the nervous system
Figure 09.09
Movement of synaptic vesicles to axon
membrane involves Calcium ions
Video
Figure 09.10
Figure 09.16
One neuron may connect with 10,000 other neurons
and you have billions of neurons. These pathways are
how memory is stored.
Nerve impulse
Figure 09.13
Nerve impulse
Action Potential or Wave of Depolarization
A Polarized or Resting neuron is + on the outside and – on the inside
due to Na on the outside and K on the inside.
When an impulse is initiated gates in the cell membrane open and the two
chemical exchange places producing a wave of depolarization that travels
down the axon.
The nerve will repolarize by diffusion for quick impulses
Prolong impulses can cause to neuron to remain depolarized so cannot
carry any more impulses it is said to be in a Refractory Period
To repolarize this neuron requires an active transport system call the
Sodium – Potassium Pump
Video
Figure 09.14
Polarized or Resting
Neuron
Wave of Depolarization
Figure 09.15
Figure 09.17
- A bundle of many neurons
Figure 09.18
Figure 09.19
Posterior Horn
Anterior Horn
Motor neurons come from the Anterior Horn of the
spinal cord so are referred to as anterior horn cells
Sensory neurons enter through the Posterior Horn of
the Spinal cord so are called posterior horn cells
Figure 09.20
Figure 09.21
Central Nervous System
Figure 09.22
Figure 09.23
Figure 09.24
Gray Matter
Unmyelinated neurons
White matter
myelinated neurons
Figure 09.25
How do you
know if it is hot
or cold ?
Figure 09.26
How did you walk to
class ?
Figure 09.27a
Nerve connection
between hemispheres
“Bridge”
Gyrus: Top of folds Sulcus : Valleys of folds
Increases the surface area of the cortex
Meninges: Protective cover of brain 3 layers 1. Dura Mater “ tough mother” outer layer 2. Arachnoid
“ Spider web” layer of connective fibers 3. Pia mater “gentle mother” touches brain
Diencephalon: Midbrain - Thalamus, Epithalamus and Hypothalamus All sensory input goes
through Thalamus before going to Cerebral Cortex. Hypothalamus does many functions for the autonomic
nervous system ( Body Temp., Thirst, Appetite, Emotions, Mating, Sleep, Memory, Hormones )
Figure 09.27b
Figure 09.28
Brodmann’s map based on cell structure and function
Figure 09.29
Figure 09.30
Cavities filled with cerebrospinal fluid
CSF – cools the brain,
brings in nutrients and
removes waste
Figure 09.31
Figure 09.32
Figure 09.34
Figure 09.35
“ Horsetail”
Lowest point of spinal cord
Figure 09.36
Figure 09.37
Figure 09.38
Figure 09.39
TABLES
Table 09.01
Table 09.02
Table 09.03
Table 09.04
Table 09.06
Table 09.07