Lecture9
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Transcript of Lecture9
Lecture 9: Brain Organization
Reading: Ch 5, sections: organization, cerebral cortex, cerebellum and brainstem, spinal cord Ch 7, section: autonomic nervous system
Conduction speed on myelinated axons ~ 120 m/s
Longest axon ~ meter long (big toe to spinal cord)
Total travel time for a nerve impulse from head to toe: 10 ms + 10 ms + 1-2 ms per synapse = ~ 25 ms
Brain
sensory inputs
motor outputs
Body
Sensory-motor transformation
Central Nervous System (CNS)A. Brain
1. Forebraina. Cerebral
Cortexb. Basal
Gangliac.
Thalamusd. Limbic
System2. Brainstem
a. Midbrain
b. Ponsc.
Medulla Oblongata3. Cerebellum
a. Cerebellar Cortex
b. Deep Nuclei
B. Spinal Cord1. Sensory2. Motor
Peripheral Nervous System (PNS)A. Somatic Division
1. Sensory2. Motor
B. Autonomic Division1. Sympathetic2. Parasympathetic3. Enteric
cerebrum
diencephalon
Gray Matter vs. White Matter (not in notes)
Brain Spinal Cord
Gray Matter – Nervous Tissue that primarily contains cell bodies
White Matter – Nervous Tissue that primarily contains axons
Graymatter
Cerebrum - portion of the CNS largely responsible for all of the higher cognitive, sensory and motor
functions of the brain.
Cerebral Cortex - the outer, highly folded surface of the cerebrum.
CNS\Brain\Forebrain\Cerebrum\Cerebral Cortex:
4 Lobes - Frontal, Parietal, Temporal, and Occipital Lobes
CNS\Brain\Forebrain\Cerebrum\Cerebral Cortex:
“Functional Localization”
Primary Visual Cortex – Occipital LobePrimary Auditory Cortex – Temporal Lobe
Primary Motor Cortex – Frontal LobeSomatosensory Cortex – Parietal Lobe
Examples:
Sensory Homunculus
CNS\Brain\Forebrain\Cerebrum\Cerebral Cortex (cont.)
- orderly mapping of body parts- overrepresentation of regions with great acuity (hand and head)
General Theme:
Basal Ganglia Set of large nuclei lying in the center of the brain, highly connected with the cerebral cortex the thalamus.
(see next slide)
Thalamus Large nucleus, composed of many smaller subnuclei, lying in the center of the brain just posterior to the Basal Ganglia. Functions cooperatively with, and is highly connected to, the cerebral cortex.
(see next slide)
CNS\Brain\Forebrain\Cerebrum:
CNS\Brain\Forebrain\Diencephalon:
Limbic System - Collection of nuclei, interconnected to the thalamus and cerebral cortex, that
play a key role in learning, memory and emotions.
CNS\Brain\Forebrain\:
Brainstem - evolutionarily older (so-called reptilian) portion of the CNS, essential for the maintenance of life and many autonomic functions.
1) Midbrain - the upper portion of the brainstem.
2) Pons - the middle portion of the brainstem.
3) Medulla Oblongata - the lower portion of the brainstem continuous with the spinal cord.
CNS\Brain\Brainstem\:
Cerebellum Large neural lobe located on the lower posterior region of the brain, involved in numerous functions, particularly important in the control of motor coordination.
CNS\Brain\Cerebellum\:
CNS\Brain\Cerebellum\:
Cerebellar Cortex - The outer, highly folded surface of the cerebellum.
Deep Nuclei - Nuclear structures, analogous to the Basal Ganglia in the cerebrum, that lie below the cortex in the depth of the cerebellum.
CNS\Spinal Cord\:
Spinal Cord - Column of neural tissue from the medulla to the lower end of the spinal column. Contains the input and output pathways of the CNS.
Sensory - subdivision that processes and relays somatic sensory information to the cerebrum.
Motor - subdivision that processes and relays somatic motor information to the somatic musculature.
CNS\Spinal Cord\:
A. Somatic Division - portion of the PNS containing all of the somatic sensory and motor nerves and ganglia.
1) Sensory - somatic sensory nerves and ganglia.
2) Motor - somatic motor nerves and ganglia.
B. Autonomic Division - The portion of the PNS responsible for regulating the involuntary actions of the internal organs.
1) Sympathetic - division of the autonomic nervous system that prepares the body for strenuous physical activity.
2) Parasympathetic - division of the autonomic nervous system that maintains resting functions of the internal organs.
3) Enteric - division of the autonomic nervous system that regulates the functions of the gut.
PNS\
Peripheral Nervous System (PNS) - that portion of the nervous system not located within the skull or the spinal column.
PNS\Autonomic Division\ Neurotransmitters
Parasympathetic System – Acetyl Choline (ACh)Sympathetic System – ACh, …Norepinephrine (NE)/Epinephrine (E)