PSYC 100 Lecture Notes - Lecture 5: Agonist, Threshold Potential, Action Potential

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10 Aug 2016
Department
Course
PSYC 100 - Unit 2
Neuroscience I - The Neuron
The Nervous System
Term Notes
Central Nervous
System
-composed of the brain and the spinal cord, neurons and glial cells
-glial cells serve supportive and protective functions, supply oxygen and
nutrients to neurons, remove dead cells and germs, and serve as a
protective layer around axons
Peripheral Nervous
System
-made up of skeletal NS, sensory/afferent NS, motor/efferent NS, autonomic
NS, sympathetic and parasympathetic NS
-includes nerves from spinal cord and sensory organs, which transmit sensory info
from the body → CNS, and motor info and other commands from CNS → muscles,
glands, organs
Skeletal NS - Controls muscles, relaying motor commands from the brain
Autonomic NS - Controls involuntary muscles and many internal organs, plays an important
part in homeostasis
-Divided into Sympathetic and Parasympathetic division
Sympathetic - Fight or Flight, high arousal/alertness, mobilizes body for rapid energy
expenditure, inhibits digestion
Parasympathetic - Rest and Digest, enhances internal process related to digestion of food
NEURONS
Specialized cells capable of transmitting info
1. Nucleus - contains genes, directs manufacturing of protein that runs the cell
2. Dendrites - receive information
3. Cell Body - contains structures that maintain cell health and metabolism
4. Axon - transmit info from one neuron to the next
5. Myelin Sheath - covers the axon to insulate it and make impulses travel along the axon faster and move
efficiently
6. Axon/Synaptic Terminal - sends info across a synapse using neurotransmitters or electrical impulses
7. Synapse - gap between two neurons
Sensory Neurons → detect info from physical world, pass info to brain (afferent → brain)
Motor Neurons → direct muscle contractions/dilations, efferent because brain → body
Interneurons → any neuron that is neither sensory or motor, link together to integrate and communicate info
Neuron → Individual nerve cell
Nerve → bundle of axon fibres
Tracts → nerves entirely within the brain and spinal cord
Interneurons connect sensory & motor systems directly, triggering a reflex.
The brain itself may never be involved in this behaviour, as the system bypasses the brain. This is because the
brain would otherwise slow down the reaction time.
The brain later becomes aware of this phenomenon so that you avoid the behaviour.
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