PSYC 2160 Lecture Notes - Lecture 5: Axon Hillock, Pia Mater, Cerebrospinal Fluid
CH 3 ANATOMY OF THE NERVOUS SYSTEM
Continued
Excitatory & Inhibitory Post-synaptic Potentials or EPSPs & IPSPs (Local Potentials)
–excitatory Nts bind to receptors opening ligand-gated Na+ channels producing EPSPs in
post-synaptic neuron
–axon hillock reaches threshold of activation triggering an AP
–inhibitory Nts bind to receptors opening ligand-gated K+ or Cl- channels producing
IPSPs in post-synaptic neuron
–IPSPs counteract EPSPs; threshold of activation is not reached no AP is generated
–inhibitory is just stopping the firing
Summation of Local Potentials over Space & Time
F3.1
CNS – is the division of the NS located within the skull & spine
PNS – the division located outside of the skull & spine
Meninges (protective membrane)
–Dura Mater (tough mother) outer meninx; is tough
–Arachnoid membrane (spider-web like); is fine
→ Subarachnoid space (beneath arachnoid, contains many large blood vessels & cerebrospinal
(fluid)
–Pia mater (pious mother) innermost meninx, adheres to the surface of the CNS; delicate
Ventricles & Cerebrospinal Fluid
–CSF also protects the CNS which fills the subarachnoid space, the central canal of the
spinal cord and the cerebral ventricles of the brain
–CSF supports & cushions the brain
–CSF is produced by choroid plexuses (traditional view)
Blood-Brain Pressure
–fortunately a mechanism impedes the passage of many toxic substances from the blood
into the brain
–this barrier is a consequence of the spacial structure of cerebral blood vessels
–typically the cells that make the walls of blood vessels are loosely packed, but in the
brain they are tightly packed
Classes of Neurons
–multipolar: neuron with more than 2 processes extending form its cell body
–unipolar: a neuron with 1 process extending from its cell body
–bipolar: a neuron with 2 processes extending from its cell body
–interneurons: neurons with a short axon or no axon at all
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Document Summary
Ipsps counteract epsps; threshold of activation is not reached no ap is generated inhibitory is just stopping the firing. Summation of local potentials over space & time. Cns is the division of the ns located within the skull & spine. Pns the division located outside of the skull & spine. Dura mater (tough mother) outer meninx; is tough. Subarachnoid space (beneath arachnoid, contains many large blood vessels & cerebrospinal (fluid) Pia mater (pious mother) innermost meninx, adheres to the surface of the cns; delicate. Csf also protects the cns which fills the subarachnoid space, the central canal of the spinal cord and the cerebral ventricles of the brain. Csf is produced by choroid plexuses (traditional view) F3. 5 major external features of a neuron cell membrane: semipermeable membrane that encloses the neuron dendrites: the short processes emanating from the cell body, which receive most of the synaptic contacts from other neurons.
