EXSS NS regions

Central Nervous System (CNS)

1. Brain lies above foramen magnum

2. Spinal cord lies below foramen magnum

Peripheral Nervous System (PNS)

• 12 pairs cranial nerves

• 31 pairs spinal nerves

• Peripheral nerves

3 main functions of nervous sytem

1. Sensory
   - senses changes in the internal and external envionment

2. Integrative
   - analyzes data, stores data, decides which stimuli are important

3. Motor
   - responds to simuli through muscular contractions or glandular secretion

Spinal cord tracts

• Sensory/Ascending tracts = conduct nerve impulses to brain

• Motor/Descending tracts = conduct impulses down cord

Somatic Nervous System

• Sensory neurons and Motor Neurons to Skeletal Muscle

• 1 Neuron in pathway: Motor neurons innervate skeletal muscle to produce conscious, voluntary movements

• Effect of a motor neuron = excitation

Autonomic Nervous System (ANS)

• Operates via reflex arcs

• 2 Neurons in pathway (preganglionic + postganglionic)

• continuous flow of sensory input and motor output

• Not aware or autonomic responses, hypothalamus is control center

Autonomic Nervous System (ANS) DIVISONS

1. Sympathetic Division

2. Parasympathetic Division

• Hypothalamus balances both

Autonomic Nervous System (ANS) NEUROTRANSITTERS

Neurons classified based on neuotransmitter released

• Adrenergic = NE

• Cholinergic = ACH

Autonomic Nervous System (ANS) RECEPTORS

Nicotinic = Preganglionic, receive ACh → excitation

Adrenergic = Postgalgnlionic, receive NE → excite or inhibit

Muscarinic = Postganglionic, receives ACh → excite or inhibit

Preganglionic neurons

• Release ACH to nicotinic receptors = Excitation

Postganglionic neurons

• Release norepinephrine (NE) to adrengic receptors (SNS) or ACH to muscarinic resecptors (PNS)

Sympathetic Responses

• Fight or Flight

• Physical or emotional stress

• E situations

Sympathetic Responses Indicators

dilation of pupils, dilation of airways, respiratory rate

increases

• increase of heart rate, force of contraction & BP, blood flow to

skeletal & cardiac muscle, blood glucose levels

• increase blood pressure and mental activity

• decrease in blood flow to nonessential organs

• Some organs have only sympathetic innervation

• sweat glands, adrenal medulla, arrector pili mm & many blood

vessels

Parasympathetic responses

• Rest and Digest activities

• Conserve and restore energy during times of rest

• Actions oppose those of sympathetic system

  • Decrease HR, diamter of airways and coronary vesssels

  • Normally dominate over sympathetic impulses
    SLUDD RESPONSES

    • Salivation, lacrimation, urination, digestion, and defactation

Enteric Nervous System

Neurons V Neuroglia

3 main components of neurons

• Dendrites

• Cell body/Soma

• Axon

  • Many axon make up a nerve

Function classification of neurons

Myeline Sheath

• Multilayered lipid

• insulates axon

• Increase nerve conduction velocity

• Nucleus = Schwann cells

  • Gapes = Nodes of ranview

Myelin

Multiple Sclerosis (MS)

• Deterioration of myelin sheath

  • Sensory of motor neurons

  • Neurons become ineffective

  • Muscle atrophy

  • Decreased coordination

  • Currently no cure

Synapses

Eletrical synapse

Ionic current spreads to next cell through gap junctions

• faster, two way transmission and capable of synchronizing neurons

Chemical synapse

one way informationt ransfer from presynaptic to postsynapic neuron
neurons/cells involved do not touch but are seperates by a synaptic cleft

Pharmacology of the NMJ

Neurotransmitters

• Released form axon terminal into synaptic cleft into a response to a nerve impulse

• Effects can be modified via synthesis, release, removal, receptor site

• Agonist = enhance

• Antagonist = Blocks

Common neurotransmitters