ANATOMY AND PHYSIOLOGY

1
ANATOMY AND PHYSIOLOGY
2
NERVOUS SYSTEM
3
CENTRAL NERVOUS SYSTEM (CNS)

• brain
• spinal cord

4
PERIPHERAL NERVOUS SYSTEM (PNS)

• cranial and spinal nerves

5
DIVISIONS OF THE PNS

• SOMATIC NERVOUS SYSTEM
• SOMATIC SENSORY (afferent)
• SOMATIC MOTOR (efferent)

6
AUTONOMIC NERVOUS SYSTEM

• VISCERAL SENSORY (afferent)
• SYMPATHETIC NERVOUS SYSTEM (efferent)
• PARASYMPATHETIC NERVOUS SYSTEM (efferent)

7
CELLS OF THE NERVOUS SYSTEM

• neuroglia
• astrocytes
• microglia
• ependymal cells
• oligodendroglia

8
NEURONS (functional classification)

• motor neurons
• sensory neurons
• interneurons

9
neurons (structural classification)

• multipolar neurons
• unipolar neurons
• bipolar neurons

10
PARTS OF A TYPICAL MOTOR NEURON

• dendrites
• cell body
• nucleus
• nucleolus
• Nissl bodies
• hillock
• neurofibrils

11
parts of a neuron, cont.

• axon
• neurolemma
• telodendria
• synaptic knobs
• myelin sheath
• Schwann cells
• Nodes of Ranvier

12
FUNCTIONAL CLASSIFICATION OF NEURONS

• afferent (sensory) neurons
• efferent (motor) neurons
• interneurons

13
PARTS OF REFLEX ARC

• receptor ( like hot and cold receptors in the
  skin)
• sensory neuron
• dendrite- goes from receptor to ganglion
• sensory cell bodies are in ganglion
• axon- goes from ganglion to spinal cord
• synapse with dendrites of interneuron

14
parts of reflex arc cont.

• interneuron
• found in the posterior gray (matter) horn of
  spinal cord
• communicates between sensory and motor neurons
• motor neuron (efferent) neuron
• cell body found in the anterior gray horn
• axon goes to muscle (effector)

15
TYPES OF REFLEX ARC'S

• ipsilateral
• contralateral
• intersegmental

16
Nerve Coverings

• epineurium
• perineurium
• endoneruium

17
mixed nerves ( most)

• axons of motor nerves
• dendrites of sensory nerves
• sensory nerves
• motor nerves

18
Repair of motor nerves

• axons can be repaired
• may be some loss of muscle mass without
  stimulation

19
ACTION POTENTIAL

• stimulus needed
• threshold stimulus needed
• excess of positive ions inside results from
  diffusion of ions
• temporary (transient) negative charge on the
  outside

20
action potential

• duration of action potential 1.5 milliseconds
• magnitude of action potential is 30 mV

21
ROLE OF ION CHANNELS

• THREE TYPES OF CHANNELS

22
voltage regulated ion channels

• Voltage regulated K ion channels
• are closed during a resting membrane
• this prevents K ions from diffusing out of the
  cell

23
Voltage regulated Na ion channels

• are closed in a resting membrane
• this prevents excess Naions from diffusing into
  cell
• Na/K pump channels
• at the beginning of the resting stage pump is
  active
• the Na/K pump is active

24
polarized membrane

• there are relatively more charges on the
  outside of the membrane compared to the inside.
• Inside voltage around -70mV

25
depolarized membrane-

• there are relatively more negative charges on
  the outside of the membrane
• Potential goes from -70 mV to about 30mV

26
repolarized membrane

• membrane potential returns to -70mv

27
hyperpolarized membrane

• membrane potential drops below -70mV
• potassium channels close slower than K ion
  channels closes

28
THERE ARE FOUR PHASES OF THE ACTION POTENTIAL
29
RESTING STATE - PHASE 1

• inside of membrane (resting potential) -70mV
• more negative (less positive ions) on the inside
• than the outside of the membrane
• the Navoltage regulated ion channels are closed
• the K voltage regulated ion channels are closed

30
ACTION POTENTIAL DEPLORIZATION - PHASE 2

• Na voltage regulated ions channels open
• Na ions move (diffuse) into cell ( upswing)
• Action potential depolarization
• K ion voltage regulated channels are still closed

31
ACTION POTENTIAL REPLORIZATION- PHASE 3

• K voltage regulated ion channels open
• K ions move out by diffusion ( downswing)
• Na voltage regulated ion channels are closed

32
undershoot(after potential)- phase 4

• Na/K pump activates
• 3 Naions are pumped out of cell against the Na
  concentration gradient
• 2 K ions are pumped into the cell against the K
  concentration
• oscilloscope registers -65mv again and the Na
  channels are closed and the Kion channels are
  closed

33
REFRACTORY PERIOD

• absolute refractory period
• sodium channels inactivated can not open during
  this time
• relative refractory period
• sodium voltage regulated channels closed but
  capable of opening
• voltage regulated K ions channels begin to close

34
CONDUCTION OF ACTION POTENTIAL

• depolarization travels down the nerve
• wavelike conduction of negative charge down the
  nerve
• repolarization occurs behind the conduction of
  negative charges

35
comparisons of conduction speeds

• which is faster
• large nerves faster than small
• myelinated faster than non-myelinated
• fast fibers go to skeletal effectors
• slow fibers come from sensory affectors

36
SYNAPTIC TRANSMISSION

• structure of synapse
• synaptic knob
• synaptic clef
• post synaptic neuron membrane with receptors
• Mechanism of synaptic transmission

37
action potential reaches the synaptic know

• Ca ions channels open
• Ca ions cause release of neurotransmitter
  across synaptic clef
• neurotransmitter binds to receptors

38
excitatory

• if excitatory Na ions go out and K ions go in
• threshold potential is reached
• action potential is initiated

39
inhibitory

• if inhibitory out ward rush of K ions
• or inward rush of Cl- makes membrane less
  positive (more negative)
• membrane is hyperpolarized (gt70mV)
• action potential is inhibited

40
NEURAL NETWORKS

• converging networks
• divergent networks

41
CLASSIFICATION OF NEUROTRANSMITTERS
42
amines

• serotonin - mostly inhibitory
• histamine- mostly excitatory
• dopamine- mostly inhibitory
• epinephrine- sympathetic N.S.
• norepinephrine -sympathetic N.S.

43
amino acids

• glutamate- excitatory
• gamma-aminobutyric acid (GABA)- inhibitory
• glycine inhibitory

44
neuropeptides

• Substance P- transmits pain
• enkephalins- blocks pain
• endorphins- blocks pain

45
Acetylcholine

• excitatory
• neuromuscular junction
• deactivated by acetylcholinesterase