Download Nervous System II- The Brain, Cranial Nerves & Autonomic

Nervous System IIThe Brain, Cranial Nerves
& Autonomic Nervous System
REV 3-11
• The brain is organized into areas to make studying
its function easier.
• The forebrain includes the cerebrum and
diencephalon (the hypothalamus, thalamus,&
limbic system)
– This area is responsible for receiving and
integrating sensory input from the external
environment and determines most of our
complex behavior
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Nervous System II-the brain
• The midbrain includes the corpora
quadrigemina
– helps coordinate muscle groups and responses
to sights and sounds
• The hindbrain includes the medulla, pons and
cerebellum
– coordinates automatic and vital tasks
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Nervous System II-Cerebrum Lec 6
• Cerebrum (figure 9.1, page 73 lab manual)
– is the largest, most superior and anterior part of
the brain
– is divided into left and right “cerebral
hemispheres” by the longitudinal fissure
– each hemisphere controls the opposite side of
the body
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Nervous System II-Cerebrum Lec 6
– In the middle of the hemispheres is the corpus
callosum which enables the 2 hemispheres to
communicate and share sensory and motor
information
• Below the corpus callosum in each hemisphere
are the lateral ventricles which secrete CSF
– The outer layer of the cerebrum is called the
cerebral cortex and is primarily gray matter
– The inner portion of the cerebrum is primarily
white matter
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Nervous System II-Cerebrum Lec 6
– surface tissue of the cerebrum is covered with
sulci (grooves) and gyri (ridges) which
increase the surface area for information
exchange
– Each hemisphere is further divided into 4 lobes:
the frontal, parietal, temporal, and occipital
lobes
– all 4 lobes are involved in memory storage
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Nervous System II- Lec 6
– The frontal lobes, located in the forehead area,
initiate motor activity and are responsible for
speech and conscious thought
• these lobes may be further divided into the
prefontal lobes or cortex (the most forward area of
these lobes) which are the intellectual center
– intelligence, motivation, personality, abstract
reasoning, judgment, planning, love, concern for
others
• the premotor cortex
– skilled repetitive activities (typing) and conditioned
reflexes (Pavlov’s dog)
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Nervous System II -Frontal lobes
Lec 6
• the primary motor cortex which initiates voluntary
motor activity of the arms, legs, trunk and face
• In the dominant hemisphere only is Broca’s area
which is our primary speech center
– Broca’s area controls the speech muscles
– The parietal lobes, located behind the frontal lobes in
approximately the middle third of the cerebrum, house
the sensory, or somatosensory, cortex
• interpret sensory information from the skin and from
proprioceptors in the muscles and joints.
• integrate different sensory inputs to allow us to
interpret sensory information
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Nervous System II Lec 6-Occipital lobes
– The occipital lobes are located in the back of
the head (just before the neck area)
– house the primary visual cortex and the visual
association area (association areas allow us to
interpret/understand information)
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Nervous System II Lec 6 -Temporal Lobes
– The temporal lobes, located on the sides of the
head, house the primary auditory cortex
• auditory association area, including spoken
and written language interpretation, and
auditory memory
• if damaged, we suffer from aphasia
(Wernicke’s or receptive aphasia, Broca’s or
expressive aphasia)
• also includes the olfactory cortex (sense of
smell)
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Nervous System II Lec 6 -Diencephalon
• The Diencephalon is located above the midbrain
and under the cerebrum
– it includes the thalamus, hypothalamus and
pineal gland
– Thalamus: is a receiving, processing and
transfer center. It receives sensory signals from
other parts of the brain and the body and routes
them to the appropriate parts of the brain for
interpretation.
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Nervous System II Lec 6 -Diencephalon
– Hypothalamus: regulates the activities of the
autonomic nervous system and regulates
endocrine function including the pituitary
gland;
Also
• regulates the limbic system--the emotional
part of the brain.
– Also responsible for short term memory
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Nervous System II Lec 6 -Diencephalon
• Pineal Gland or Epithalamus:
– secretes the hormone melatonin.
– regulates the onset of sexual maturation and
serves as a biological clock
• fibers from the eye go to the pineal body and let you
know when it’s daytime/nightime
• Pituitary Gland: often called the master gland
because it controls many other glands
• Optic Chiasm: formed by the crossing of the 2
optic nerves
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Nervous System II Lec 6 -the Midbrain
• The Midbrain--conduction pathway between
higher and lower brain centers
– has some control over alertness
– controls movement of the eyes and pupil size
– houses the corpora quadrigemina, a reflex center for
the movement of the head in response to visual and
auditory stimuli
– monitors the unconscious movement of skeletal
muscles so their actions are smooth and coordinated
– contains part of the reticular activating system
• RAS controls our levels of sleep and wakefulness
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The Hindbrain or Brain Stem
• includes the medulla, pons, and cerebellum
Medulla
• contains areas that control vital automatic
functions of internal organs
– cardiac center-adjusts the force and rate of heart
contraction to meet the body’s needs
– vasomotor center-regulates blood pressure by acting
on smooth muscle in the walls of blood vessels to
constrict or dilate
– respiratory center-controls rate and depth of breathing
– other centers which regulate vomiting, hiccuping,
swallowing, coughing and sneezing
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– Pons
• connects the higher brain centers and the
spinal cord
• its respiratory nuclei work with the
respiratory centers of the medulla to control
respiratory rate and depth
• coordinates the information flow between
the cerebellum and higher brain centers
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Nervous System II Lec 6 -Hindbrain/Brain Stem
– Cerebellum
• processes information from various parts of
the brain to allow smooth, coordinated,
skilled movements
– excessive alcohol disrupts normal functioning of
the cerebellum; this is why drunk people lose the
ability to coordinate their movements including
walking a straight line
– contains the arbor vitae (white matter) which
looks like a branching tree
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Nervous System II Lec 6
• Cranial Nerves
– there are 12 pairs of cranial nerves
(this is all we will do relating to the Cranial Nerves since it
is primarily a lecture topic.)
• The Autonomic Nervous System (ANS) is also referred
to as the involuntary nervous system
– we generally cannot voluntarily control activities which
this system regulates
– this division regulates the activity of smooth muscles,
cardiac muscles, and glands
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Nervous System II Lec 6
• The ANS can be further divided into the
– the sympathetic nervous system (SNS) which
mobilizes body systems during emergency
situations
• called the fight or flight division
• nerves emerge from the thoracic and lumbar
segments of the spinal cord (also called the
thoracolumbar area)
• releases the neurotransmitters epinephrine and
norepinephrine
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Nervous System II Lec 6
– the parasympathetic nervous system (PNS)
which primarily conserves our energy use
• considered to be the “normal function” division-it keeps our body functioning under normal,
non-stressful conditions
• the nerves emerge from the brain and sacral
regions of the spinal cord
• releases the neurotransmitter acetylcholine
which has an opposite effect from the SNS
neurotransmitters
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Reminder, page 1of 2:
Lec 6
1. There is a supplementary color handout for the
sheep brain. Each table should have 1-4 copies.
DO NOT take these home.
2. Use the models to learn parts of the human brain in
the bulleted lists on pages 76 and 77.
3. For the sheep brain, use the handouts as your guide.
Learn only the items labeled in the handout. You will
not be doing actual dissection since this has already
been done.
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Reminder, page 2 of 2:
Lec 6
Nervous System II
4. Skip specifics of cranial nerves in figure 9.5 and table
9.1.
5. Learn general aspects of the Autonomic Nervous
System using figure 9.6 in the lab book.
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