PSYC 2410 Chapter Notes - Chapter 3: Hydrocephalus, Central Canal, Hindbrain
27 Jun 2018
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General layout of the nervous system
Divisions of the nervous system
oThe vertebrate nervous system is composed of two divisions: the central nervous
system and the peripheral nervous system
oThe central nervous system (CNS) is the division of the nervous system located within
the skull and spin, and the peripheral nervous system (PNS) is the division located outside
the skull and spine
oThe CNS is composed of two divisions: the brain and the spinal cord
The brain is the part of the CNS located in the skull
The spinal cord is the part located in the spine
oThe PNS is also composed of two divisions: the somatic nervous system (SNS) and the
autonomic nervous system (ANS)
SNS is the part of the PNS that interacts with the external environment
composed of afferent nerves that carry sensory signals form the skin,
skeletal muscles, joints, eyes, ears and so on to the CNS and efferent nerves that
carry motor signals from the CNS to the skeletal muscles
ANS is the part of the PNS that regulates the body's internal environment
Composed of afferent nerves that carry signals from internal organs to
the CNS and efferent nerves that carry motor signals from the CNS to internal
organs
oAfferent is going towards the CNS
oEfferent is going away from the CNS
oThe ANS has two kinds of efferent nerves: sympathetic nerves and parasympathetic
nerves
The sympathetic nerves are autonomic motor nerves that project from the CNS
in the lumbar and thoracic regions of the spinal cord
The parasympathetic nerves are those autonomic motor nerves that project
from the brain and sacral region of the region cord
oSympathetic and parasympathetic systems differ in that the sympathetic neurons that
project from the CNS synapse on second-stage neurons at a substantial distance from their
target organs, whereas the parasympathetic neurons that project from the CNS synapse
near their target organs on very short second-stage neurons
oThe conventional view of the respective functions of the two systems stresses 3
important principles:
Sympathetic nerves stimulate, organize, and mobilize energy resources in
threatening situations, whereas parasympathetic nerves act to conserve energy
Each autonomic target organ receives opposing sympathetic and
parasympathetic input, and its activity is thus controlled by relative levels of
sympathetic and parasympathetic activity
Sympathetic changes are indicative of psychological arousal, whereas
parasympathetic changes are indicative of psychological relaxation
oMost of the nerves of the PNS project from the spinal cord, but there are 12 pairs of
exceptions: the 12 pairs of cranial nerves, which project from the brain
Because the functions and locations of the cranial nerves are specific,
disruptions of particular cranial nerve functions provide excellent clues about the
location and extent of tumours and other kinds of brain pathology
Meninges
oThe brain and spinal cord are the most protected organs in the body
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Document Summary
The vertebrate nervous system is composed of two divisions: the central nervous system and the peripheral nervous system o. The central nervous system (cns) is the division of the nervous system located within the skull and spin, and the peripheral nervous system (pns) is the division located outside the skull and spine o. The cns is composed of two divisions: the brain and the spinal cord. The brain is the part of the cns located in the skull. The spinal cord is the part located in the spine o. The pns is also composed of two divisions: the somatic nervous system (sns) and the autonomic nervous system (ans) Ans is the part of the pns that regulates the body"s internal environment. Composed of afferent nerves that carry signals from internal organs to the cns and efferent nerves that carry motor signals from the cns to internal organs: afferent is going towards the cns o o.
