PSY2061 Chapter Notes - Chapter 3: Astrocyte, Sensory Cortex, Hindbrain
5 Jun 2018
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PSY2061 – Readings – Week 3 – Anatomy of the Nervous System
• divisions of the nervous system
•
o vertebrate nervous system is composed of two different divisions
o
▪ the central nervous system
▪
▪ located within the skull and spine
▪ two divisions
▪
▪ brain
▪ spinal cord
▪ peripheral nervous system
▪
▪ somatic nervous system
▪
▪ part of the PNS that interacts with the
external environment
▪ composed of afferent nerves that carry
sensory signals from the skin, skeletal
muscles, joints, eyes and so on to the central
nervous system and efferent nerves that
carry motor signals from the central nervous
system to the skeletal muscles
▪ autonomic nervous system
▪
▪ part of the peripheral nervous system that
regulates the body’s internal environment
▪ composed of afferent nerves that carry
sensory signals from internal organs to the
CNS and efferent nerves that carry motor
signals from the CNS to internal organs
▪ two kinds of efferent nerves
▪
▪ sympathetic nerves
▪
▪ autonomic motor nerves that
project from the CNS in the
lumbar - small of the back and
thoracic - chest area - regions
of the spinal cord
▪ stimulate, organise and
mobilise energy resources in
threatening situations
▪ parasympathetic nerves
▪
▪ autonomic motor nerves that
project from the brain and
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sacral - lower back region of
the spinal cord
▪ closer to target organs
▪ act to conserve energy
▪ both are two stage neural paths
▪
▪ they project from the CNS and
head part of the way to target
organs before they synapse on
other neurons that carry the
signals the rest of the way
▪ each autonomic target organ receives
opposing sympathetic and parasympathetic
input
▪ sympathetic changes are indicative of
psychological arousal whereas
parasympathetic changes are indicative of
psychological relaxation
▪ most of the nerves of the peripheral nervous system
project from the spina cord - 12 pairs of exceptions -
cranial nerves
▪
▪ project from the brain
▪ contain both sensory and motor fibres with
some purely sensory nerves
o meniges
o
▪ brain and spinal cord are covered by three protective
membranes - the three meninges
▪ outer meninx - tough membrane called the dura mater -
inside the dura mater is the fine arachnoid membrane -
beneath this is a space called the subarachnoid space -
which contains many large blood vessel and cerebrospinal
fluid - then comes the innermost menix - the pia mater -
which adheres to the surface of the CNS
• ventricles and cerebrospinal fluid
•
o also protect the CNS
o fills the subarachnoid space, the central canal of the spinal cord
and the cerebral ventricles of the brain
o
▪ central canal - small central channel that runs the length of
the spinal cord
o cerebral ventricles
o
▪ four large internal chambers of the brain
o the subarachnoid space central canal and cerebral ventricles are
interconnected by a series of openings and thus form a single
reservoir
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o cerebrospinal fluid
o
▪ supports and cushions the brain
▪ produced by the choroid plexus - networks of capillaries or
small blood vessels that produce into the ventricles from
the pia mater
▪ excess cerebrospinal fluid is continuously absorbed from
the subarachnoid space into large blood filled spaces or
dual sinuses which run through the dura mater and drain
into the large jugular beings of the neck
▪ however could be more complex than this
▪ occasionally the flow is blocked producing a condition
called hydrocephalus - treated by draining excess fluid from
the ventricles and trying to remove the obstruction
• blood brain barrier
•
o a mechanism that impedes the passage of many toxic substances
from the blood into the brain
o consequence of the special structure of cerebral blood vessels
o in the brain - cells of the blood vessel walls are tightly packed thus
forming a barrier to the passage of many molecules - however
does not impede the passage of all large molecules - some large
molecules such as glucose are critical for normal brain function
o many CNS disorders are associated with the impairment of the
blood brain barrier
• cells of the nervous system
•
o anatomy of neurons
o
▪ neurons are cells that are specialised for the reception,
conduction and transmission of electrochemical signals
▪ external anatomy
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