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Chapter 12. Neural Tissue. deals with information. sense information process information respond to information. PNS. “nerves” cranial spinal. Overview of classification:. Anatomical. CNS. PNS. “nerves” cranial spinal. brain and spinal cord. somatic autonomic.
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Chapter 12 Neural Tissue
deals with information sense information process information respond to information
PNS “nerves” cranial spinal Overview of classification: Anatomical CNS PNS “nerves” cranial spinal brain and spinal cord
somatic autonomic Overview of classificaton: Functional: CNS afferent (carry to) efferent (bring out) sensory motor receptors
cells: neurons processes soma fig. 12-1
axonal transport material moving anterograde cell body synapse retrograde
neural tissue neurons information neuroglia (glial cells) protection nourishment insulation modulation
neural tissue neuroglia (CNS) ependymal cells astrocytesoligodendrocytes microglia
neural tissue neuroglia (CNS) ependymal cells • line cavities of CNS • produce CSF • (cerebrospinal fluid)
neural tissue neuroglia (CNS) ependymal cells astrocytes blood-brain barrier structural support nourish neurons
neural tissue neuroglia neuroglia (CNS) ependymal cells astrocytesoligodendrocytes • wrap around axons • myelin
neural tissue neuroglia (CNS) ependymal cells astrocytesoligodendrocytes microglia smallest clean up debris
ependymal astrocytes oligodendrocytes microglia fig. 12-4
neural tissue neuroglia (PNS) satellite cells like astrocytes in CNS Schwann cells like oligo’s in CNS
PNS fig. 12-6
anatomy physiology how do the cells send information?
cells: neurons processes synapses fig. 12-1
3 “potentials” fig. 12-7
= / resting potential ICF ECF K+ proteins- Na+ Cl- +++++ -------
chemical gradient ICF ECF K+ Na+
electrical gradient ICF ECF K+ Na+ +++++ -------
when at resting potential… fig 12-9a
if membrane was freely permeable to potassium… fig 12-9b
when at resting potential… fig 12-9c
if membrane was freely permeable to sodium… fig 12-9d
= / resting potential ICF ECF K+ Na+ +++++ -------
membrane proteins and the distribution and movement of ions 1. leak channels 2. Na+/K+ pump 3. gated channels: a. chemically regulated channels b. voltage-regulated channels c. mechanically regulated channels 1. leak channels 2. Na+/K+ pump
membrane proteins and the distribution and movement of ions leak channels K+ Na+ Na+/K+ pump ATP (active transport)
Na+ leaks in K+ leaks out (always open) Na+/K+ pump (ATPase) pumps Na+ back out pumps K+ back in maintains resting potential = -70 mV
oscilloscope millivolts 0 membrane is polarized resting potential -70 time --->
membrane proteins and the distribution and movement of ions • potentials: • resting potential • graded potentials • action potentials
membrane proteins and the distribution and movement of ions 1. leak channels 2. Na+/K+ pump 3. gated channels: a. chemically regulated channels b. voltage-regulated channels c. mechanically regulated channels
a. chemically regulated channels • signal binds • (stimulus) • channel opens e.g., AChR fig. 12-10a
b. voltage-regulated channels Na+ -70 mV closed -60 mV open 1/1000 sec +30 mV closed inactivated fig. 12-10b
c. mechanically regulated channels closed mechanical stimulus- opens remove stimulus- closed fig. 12-10c
membrane proteins and the distribution and movement of ions 1. leak channels 2. Na+/K+ pump 3. gated channels: a. chemically regulated channels b. voltage-regulated channels c. mechanically regulated channels
membrane proteins and the distribution and movement of ions • potentials: • resting potential • graded potentials • action potentials fig. 12-7
de repolarized Na+ in oscilloscope millivolts 0 polarized -70 time --->
graded potentials • local potentials • short range • only affect a • small portion of the cell • (may trigger “events” in other cells) action potentials a potential that is propagated along an axon (affects the whole cell)
? - a stimulus large enough to open • the Na voltage-gated channels “threshold” about -60 mV
Na+ voltage-gated channel • normally closed (activation gate) • at resting potential most abundant in the membrane of the axon
Na+ voltage-gated channel opens at -60mV lets Na+ in membrane depolarizes fig.12-10b