Unit 1 PP

Nervous system intro

Stem cells

undifferentiated cells that have the ability to proliferate and become diff cell types

Neurons

type of stem cells, responsible for transmitting electrical signals in the nervous system.

Glial cell

type of stem cells, provide metabolic support, protection, and insulation for neurons

Ependymal cell

• The pink cell in pic

• Responsible for SECRETING CSF

Microglia

• Red cell in pic

• Defensive function : performs phagocutosis ; provides immune system function

Astrocyte

• Green cell in pic

• Provides structural support, maintains ionic/chem enviornment ; nutritive role; phagocytocis

Oligodendroglia

• Blue cell in pic

• Mylenates multiple axons in CNS

Schwann cell

• mylenates one axon in PNS

Motor neuron

direct biobehavioral responses appropriate for the situation.

Sensory neurons

convert physical stimuli into electrical signals.

Interneurons

• neurons in brain and spinal cord;

• form interacting neural circuits; responsible for conscious sensations, recognition, memory, decision-making, cognition.

Soma

cell body; contains nucleus and other organelles

Dendrites

• projections from the soma that receive information.

• Effect on receiving cell may be excitatory or inhibitory

Axon

extension that conducts electrical signals from the cell body to the terminal

buttons

Convergence

a neuron receives and integrates a vast amount of information from many cells.

Divergence

the integrated information can be transmitted to a few or thousands of other

neurons.

Nodes of Ranvier

• Breaks in the myelin sheath

• the sites where action potentials are regenerated.

• The myelin sheath increases speed of conduction along the axon; the thicker

the myelin, the faster the conduction.

receptors

Initial sites of action of neurotransmitters, hormones, and drugs

enzymes

that catalyze biochemical reactions.

ion channels and transporters

for charged molecules such as amino acids, glucose, and

metabolic products.

Ligand-gated channel

opens when a ligand binds to a receptor.

Voltage-gated channel

opens when the electrical potential across the membrane is altered.

ATP

• Brains energy source - mitochondria

• Rate of ATP synthesis reflects neuron

  activity; this is used in techniques that

  allow visualization of brain function

• is also an extracellular signaling

  molecule between neurons and glia

Resting membrane potential:

• not sending a signal = –70 millivolts (mV)

• inside the cell = it is polarized.

• There are more negative ions (and amino acids) inside the cell, and more positive ions outside.

K+ movement

• moves into the cell because it is attracted to the negatively charged

  particles (electrostatic pressure).

• moves back out of cell when its concentration rises (concentration

  gradient

Na+–K+ pump

• moves 3 Na+ to the outside for every 2 K+ moved to the inside. (against their concentration gradient)

Action potential (AP)

• rapid change in membrane potential

• THRESHOLD = –50 mV.

• Voltage-gated Na+ channels open, generating a rapid change in membrane potential

• all or none

Local potentials

• Ion channels open momentarily, causing small, local changes in ion

distribution and potential differences

If Na+ channels open

local depolarization

If Cl– channels are stimulated to open

hyperpolarization, which is inhibitory.

n myelinated axon, onduction seems to jump along the

axon—saltatory conduction.

This neuron is at what state?

Resting (polarized)

An action potential will be propagated only if a stimulus reaches a

Threshold value

The two most important characteristics of the action potential's transmission are

Depolarization and hyperpolarization

In myelinated axons, regeneration of the action potential occurs only at

the nodes of ranvier

SNS

Pregang = Ach

Postgang = Ne

PNS

Pregang = Ach

Postgang = Ach

SNS division

thoracic - lumbar

PNS division

Cranial nerves + sacral spinal cord

Spinal cord:

gray matter contains neuron cell bodies; white matter is myelinated axons.

Sensory afferent nerves

• Carry information to the spinal cord;

• soma are in the dorsal root ganglia.

Motor efferent nerves

• result in voluntary movement; soma are in ventral horn.

Meninges

layers of tissue that cover and

protect the brain and spinal cord

ORDER OF LAYERS (thoughest to thinnest)

1. Dura matter

2. Arachnoid mattter (has subarachnoid filled with csf)

3. Pia matter

CSF

• surrounds brain and spinal cord, fills the

  cerebral ventricles and the central channel in

  the spinal cord

CSF is formed in

choroid plexus

Telencephalon

neocortex, basal ganglia, Limbic system

Diencephalon

Thalumus, hyptohalamus

Mesencephalon

Midbrain

Metencephalonn

Cerebellum, pons

Myencephalon

Medulla

Horizontal

sagital

coronal