nervous system divisions central nervous system –brain & spinal chord peripheral nervous...
TRANSCRIPT
Nervous System
Divisions• Central Nervous
System– Brain & Spinal Chord
• Peripheral Nervous System– Autonomic-involuntary
– Somatic-voluntary
Neurons I
• Nerve=bundle of neurons
• Neurons draw and label) have:
• 1. Cell Body– Nucleus and
organelles
• 2. Dendrites– Receive impulses
Neurons II
• 3. Axon– Always only 1– Conducts impulse AWAY from
cell body– Encased by Schwann cells
Myelin sheath– Nodes of Ranvier
• Three types of neurons-• Sensory Neurons (from sense receptors
to central nervous system)
• Interneurons (relay info to Motor neurons)
• Motor Neurons (From CNS to body)
Action Potential – Resting I• Resting Potential (-70mV)
– Result of unequal distribution of ions– At rest, more positive (Na+) on outside– During signal, NA+ moves inside neuron
Action Potential – Resting II
• Concentration Gradient• 3 Na+ (sodium) vs. 2
K+ (potassium)• Active transport-does it
use energy?
Action Potential III
• How does the myelin sheath improve conductance speed?
• impulse jumps! between Nodes of Ranvier
All or none!
• Threshold Stimulus
• Subthreshold – those stimuli that are weaker than threshold (No AP)
Synaptic Gap
• Spaces between neurons
• Synaptic vesicles at bulb (end of axon) contain neurotransmitters
• Show video clip
Chemical Influences
• How might stimulants work? (Amphetamines, caffeine, nicotine)– Increase synaptic transmission increased
energy/mood, decreased appetite.• Increased irritability and anxiety
• How might depressants work? (Alcohol, anti-anxiety drugs, heroin)– Inhibition of impulses (blocking receptors of
NT• Can result in depression
Spinal Reflexes
• Does not reach higher brain levels!– No thought involved
1. Receptor Stimulated
2. Sensory
3. Association neurons in spinal column
4. (Multiple) Motor signal
5. Effectors (muscles…)
Reflex test
• Try the knee-jerk reflex yourself. – Do you have any voluntary
control?
• Can you find any other places on your body that have a similar reflex?– What do the knee-jerk and
other reflex spots have in common?