Mod 3 & 4: The Biology of Behavior Flashcards
Neurons
Nerve cells. Communicators of the brain, continually sending and receiving messages in the form of electrochemical signals.
What are the three types of neurons?
Sensory, Motor and Interneurons
Sensory neurons
Carry messages from the body tissues and sensory receptors inward toward the brain and spinal cord for processing. We have a few million of these
Motor Neurons
Carry instructions from the central nervous system to outward to the body’s muscles. We have a few million of these
Interneurons
process sensory input and motor output. We have billions of these
The main structures of neurons
Cell bodies, dendrites, axons (axon terminals), myelin sheaths, glial cells
Cell Body
Houses of the nucleus of the cell, all the cell’s life support functions occur here.
Dendrites
receive information from other neurons. And move it toward the cell body.
Axon
delivers messages from neuron to other neurons, muscles or glands, through its terminal branches
Axon Terminal (aka presynaptic terminal, end foot, terminal branches of axon)
end of axon, forms junctions with other neurons, release neurotransmitters.
May be several feet long through the body
Myelin Sheath
layers of supportive cells which act to insulate axon and speed up the signal.
• as it is laid down (up to age 25) neural efficiency, judgement, and self-control all increase
• if it degenerates multiple sclerosis occurs
Glial Cells
provide nutrients and insulating myelin, guide neural connections and clean up after neurons send messages to each other
Neural Impulse
When stimulated by senses or triggered by chemical response, neurons transmit messages to each other. In response to that neurons fire impulses
Action potential
a brief electrical charge that travels down its axon
-2 to 180 mph – this is still 3 million times slower than electricity through wire
excitatory and inhibitory signals
Some signals are excitatory (like pushing an accelerator) some are inhibitory (like pushing a brake)
• If excitatory minus inhibitory exceeds a minimum intensity (threshold) the combined signals trigger an action potential.
• Increasing the level of stimulation above the threshold will not increase the neural impulses intensity. It’s an all or none response.
Synapses
the junction between the axon tip and the sending neuron and the dendrite or cell body of the receiving junction discovered by Sir Charles Sherrington
synaptic gap or cleft
the gap between the synapses and the dendrite or cell body
neurotransmitters
When action potentials meet the end of the axon it releases the chemical messengers
Within one ten thousandth of a second the neurotransmitter molecules cross the synaptic gap and bind to receptor sites on the receiving neuron. It locks on for a split second and unlocks tiny channels at the receiving site and electrically charged atoms flow in exciting or inhibiting the receiving neurons readiness to fire reuptake occurs the sending neuron reabsorbs the neurotransmitters from the synapsis
Acetylcholine (ACh)
- Enables muscles action, learning and memory
- Is the messenger at every junction between motor neurons and skeletal neurons
- When released to our muscle cell receptors the muscle contract
Endorphins
The brains own naturally produced opiates
endogens [produced within] morphine
Why not just create artificial opiates to intensify the brains ‘feel good’ chemistry?
o When flooded with opiate drugs such as morphine and heroine the brain may stop creating its own natural opiates
o When the drugs are withdrawn the brain has no opiates left leaving you with intense discomfort.
Formed by the brain and spinal cord, the ____ is the body’s decision maker
Central Nervous System (CNS)
The brains neurons cluster into work groups called ____
neural networks
Peripheral Nervous System (PNS)
Responsible for gathering information and transmitting CNS data to other body parts
The two components of the PNS
Somatic Nervous System (skeletal nervous system) & Autonomic nervous system ANS