CNS

SESORY RECEPTORS – DETECTS STIMULUS
MOTOR EFFECTORS – RESPOND STIMULUS

NEURONS AND GLIAL CELLS MAKE UP NERVOUS SYSTEM

Sensory Neurons – afferent – carries to CNS
Motor Neurons – Efferent - from impulses to CNS to muscles and glands
Interneurons – Association – reflexes, learning and memory

Glial Cells – NOT involved in signal processing
8 roles
1. static support of neurons
2. insulation of nerve cell – OLIGODENDROCYTES – SCHWANN
3. removal of debribs after injury of the cell dies
4. take up of chemical transmitter
5. migration and growth of axon development
6. PRE-SYNAPTIC TERMINAL
7. blood brain barriers – ASTROCYTES
8. growth hormones and food for nerve cell

OLIGODENDROCYTES(CNS) – SCHWANN (PNS) – Myelsin Sheaths

Nerve Cells – also called neurons
Cell Body – soma – metabolic center
Dendrites – imput from other neurons
Axons – ONLY OUT PUT – output = action potential = transient. Action potential is triggered at the axon HILLOCK and travels 1 – 100 ms-1
Pre-Synaptic terminals – release chemical transmitter

NEURONS –
Cell Body , Axons, supporting cells ( neuroglia ) , Oligodendrites (CNS)
Dendrties , Schwann Cells (PNS) myelinated , Nodes of Ranvier

Axons – away from cell body
Smooth surface
Only 1 axon per cell
NO RIBOSOMES NO RIBOSOMES NO RIBOSOMES NO RIBOSOMES
MYELIN
Branches further for the cell body

Dendrites – to cell body
Rough Surface (dendritic spines)
Many dendrites per cell
RIBOSOMES
NO MYELIN NO MYELIN NO MYELIN
Branch near cell body

Basic Info

IONS – CHARGED PARTICLES
ANIONS – ------- (NEGATIVE PARTICLES) ---------
CATIONS - ++++ (POSITIVE PARTICLES) ++++++

Ionic movement is caused by
1. Electrostatic Forces (+ attracts, same charge repel)
2. Concentration Forces (diffusion – movement of ions) and (osmosis)
3. Hydrostatics Forces – gravity forces upon osmosis

Permeability
1. Neuronal Membranes
2. Hydrophobic Lipid Bi-Layer
3. Gated Ion Channels
4. Non-gated Ion Channels



Resting membrane Potential

One positive pole – side exposed to extra-cellar fluid
One Negative pole –side exposed to cytoplasm

NOT Being stimulated – resting membrane potential (avg testing of -70(mV)
****Inside of cell is positively charged because of Sodium-potassium pump and Ion leakage channels ***

Resting membrane Potential

Sodium-potassium pump – every 3 Na+ (sodium ions) pumped out brings in 2 potassium ions (K+) – concentration gradient = high K+, low Na+ inside the cell and High Na+ and low K+ concentrations outside the cell
Ion leakage channels – leaks more K+ than Na+

-70 – 30 --------RESTING MEMBRANE POTENTIAL

Graded Potentials
The response to stimuli
Dendrites and cell body
Different gradations
Decremental Conduction - the further they must travel the weaker they become
EXCITATORY OR INHIBITORY


Synaptic Integration
Spatial Summation – many dendrites produce EPSPs
EPSPs - excitatory postsynaptic potential

Temporal Summation


Structure of Synapses

Intercellular junctions
Synaptic Cleft –
Receiving cell – POST SYNAPTIC

Presnaptic axon – contain neurotransmitters
Diffuse rapidly to the other side of the cleft, bind to the receptor proteins in the membrane of the POSTsynaptic cell

NEUROTRANSMITTERS
Acetylcholine – neuron and skeletal muscle
Glumate – MAJOR EXCITATORY in CNS
Glyine – Inhibition & GABA
Dopamine – BRAIN, body movement (parkinson’s)
Norepinephrine – brain and automatic neurons
Serotonin – sleep regulation

Addiction

Cell decrease the number of receptors because of an abundance of nuerotranmitters

Vertebrate Brains

Hindbrain - RHOMBENCEPHALON
Midbrain - MESENCEPHALON
Forebrain – PROSENCEPHALON


Forebrain –
Basal Ganglia
Thalamus
Hypothalamus







Cerebral Cortex – outer layer of the CEREBRUM a lot of neural activity of the cerebellum
Contains 10% of brains neurons
MOTER< SENSORY< ASSOCIATIVE


Cerebrum – RIGHT AND LEFT
Left cerebral hemishphere – connected to corpus callosum
Highly convoluted surface (increases surface area)
3 regions



Cerbrial Cortex
Primary Motor Cortex
Primary Somatosensory cortex
Association Cortex


Nerves – bundles of axons bound by connective tissue

Ganglia – AGGREGATES of neuron cell bodies

PNS
Sensory – DORSAL ROOT
Motor- axons leave from ventral surface and from VENTRAL ROOT of spinal

Automatic Nervous System
Parasympathetic divisions & SYMPATHETIC & MEDULLA OBLONGATA
2 neurons
Preganglionic Neuron – smooth or cardiac muscle or glands
Postgangkionic – exits the ganglion and regulates visceral effectors