sympathetic parasympathetic
nervous system nervous system
• Somatic nervous system communicates w/ external environment;
o Afferent nerves carry sensory signals
o Efferent nerves carry motor signals
o → from sensory organs to CNS
• Autonomic nervous system regulates body’s internal environment;
o Afferent nerves carry sensory signals
o Efferent nerves carry motor signals;
▪ Sympathetic nerves= autonomic motor nerves projecting from CNS
▪ Parasympathetic nerves= autonomic motor nerves projecting from
brain
o →from internal organs to CNS
• 12 pairs of cranial nerves
o Project from brain
o Some purely sensory→ olfactory and optic
o Most both sensory and motor
Meninges
brain and spine (CNS) is the most protected organ in the body→ 3 protective membranes=
meninges
, 1. Dura mater= outer meninx
2. Arachnoid membrane→ inside dura mater
a. Beneath arachnoid membrane is subarachnoid space
3. Pia mater= innermost meninx
Ventricles and cerebrospinal fluid
Also protecting CNS= cerebrospinal fluid→ fills;
• Subarachnoid space
• Central canal; small central channel running length of spinal cord
• Cerebral ventricles; 4 large internal chambers of brain
o 2 lateral ventricles
o Third ventricle
o Fourth ventricle
• →interconnected by openings, form single reservoir
• Supports and cushions brain
• Produced by choroid plexuses
• Excess cerebrospinal fluid absorbed from subarachnoid space into blood filled
spaces= dural sinuses → run through dura mater and drain into jugular veins of neck
• Build up of fluid→ walls ventricles and thus brain expand= waterhead; hydrocephalus
Blood-brain barrier
= mechanism impeding passage of many toxic substances from blood into brain→
consequence of special structure of cerebral blood vessels
• Cells of blood walls tightly packed→ barrier to passage many molecules;
o Proteins
o Large molecules
, • Degree to which drugs can influence activity depends on ease w/ which they
penetrate blood-brain barrier
• Some large molecules (Glucose) critical for normal brain function→ actively
transported through central blood vessel walls
• Many CNS disorders associated w/ impairment blood-brain barrier
Cells of the nervous system
1. Neurons= cells specialized for the reception, conduction and transmission of
electrochemical signals
a. External anatomy of neurons
b.
c. Internal anatomy of neurons
, d.
e. Neuron cell membrane= composed of lipid bilayer;
i. Protein molecules→ basis functional properties ;
1. Channel proteins
2. Signal proteins
f. Classes of neurons
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