Nerve activates contraction - Silver Falls School District
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Transcript Nerve activates contraction - Silver Falls School District
Chapter 7
The Brain
Regions of the Brain
1. Cerebral
hemispheres
2. Diencephalon
3. Brain stem
4. Cerebellum
A good indication of intelligence is brain weight in relation to body weight. Sperm whale = largest brain 20 lbs.
Mammal Body weight
Blue whale
60 000 kg
Lion
200 kg
Rat
200 g
Human
70 kg
Brain weight
6kg
200g
3g
1.3 kg
How much of the animal is its brain?
0.01%
0.1%
1.5%
1.9%
1. Cerebral Hemispheres (Cerebrum)
Paired (left and
right) superior
more than half
of brain mass
Gyrus, sulcus,
lobes & fissure,
gray VS white
Figure 7.13a
Specialized Area of the Cerebrum
Figure 7.13c
Layers of the Cerebrum
White matter
Fiber tracts
inside the gray
matter
Example:
corpus callosum
connects
hemispheres
Basal nuclei –
internal islands
of gray matter
Figure 7.13a
2. Diencephalon- Top of brain stem, in cerebrum
3 parts
Epithalamus - has pineal body
(an endocrine gland) & choroid
plexus – makes cerebrospinal
fluid
Thalamus -Transfers impulses to
correct part of the cortex
localization and interpretation
Hypothalamus - autonomic NS
system center (regulates temp,
water balance, metabolism),
limbic sys (emotions); connects to
pituitary gland.
3. Brain Stem - Attaches to the spinal cord
Midbrain Reflex centers for
M
vision & hearing
Pons Mostly fiber tracts;
P
nuclei involved in control of
breathing
Medulla oblongata Merges
•
•
•
•
•
w/spinal cord; control centers
for:
Heart rate control
Blood pressure regulation
Breathing
Swallowing
Vomiting
MO
4. Cerebellum
2 hemispheres
with convoluted
surfaces
involuntary
coordination of
body
movements
Protection of the CNS
1. Scalp and skin
4. Cerebrospinal fluid
2. Skull & vertebrae
5. Blood brain barrier
3. Meninges
3. Meninges – connective tissue
Dura mater - Double-layered
external covering; folds inward
-Periosteal – attached to
surface of the skull
-Meningeal layer – outer
covering of the brain
Arachnoid layer – Middle,
web-like layer
Pia mater - Internal layer,
Clings to the surface of the
brain
4. Cerebrospinal Fluid
Similar to blood plasma
Formed by choroid plexus
watery cushion to protect the brain
Circulated in arachnoid space, ventricles, &
central canal of the spinal cord
5. Blood Brain Barrier
Includes the least permeable capillaries
Excludes many potentially harmful
substances
Useless against some substances
Fats and fat soluble molecules
Respiratory gases
Alcohol
Nicotine
Anesthesia
Cranial Nerves
12 pairs of nerves
that mostly serve
the head and neck
Numbered in
order, front to
back
Most are mixed
nerves, but three
are sensory only
Spinal Cord Anatomy
Exterior white matter – conduction tracts
Internal gray matter - mostly cell bodies
- Dorsal (posterior) horns
- Anterior (ventral) horns
Central canal filled w/ cerebrospinal fluid
Spinal Cord Anatomy
Meninges cover spinal cord
Nerves leave at each
vertebrae
Dorsal root
Associated with the dorsal
root ganglia – collections of
cell bodies outside the central
nervous system
Ventral root
Spinal Nerves
pair of nerves at
each vertebrae - 31
pairs
formed by
combination of
ventral & dorsal
roots of the spinal
cord
nerves are named
for the region from
which they arise
Anatomy of Spinal Nerves
Spinal nerves
divide soon after
leaving the spinal
cord
Dorsal rami – serve
the skin and muscles
of the posterior trunk
Ventral rami – forms
a complex of
networks (plexus) for
the anterior
Figure 7.22b
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 7.65
Examples of Nerve Distribution
Figure 7.23