Biology and Behavior

Psych Test 2

The nervous system

• command center of the body that controls what we think, how we feel and how we move.

• brain, spinal cord, nerves

• divided into CNS and PNS

Neuron

• cells that receive, integrate, and transmit info to the nervous system 

• 3 types- sensory, motor, interneuron 

• communicate with chemical signals through neural networks 

cell body

info received by the dendrites from thousands of other neurons is collected and integrated (Soma) 

axon 

once the info is integrated in the cell body, electrical impulses are transmitted along a long, narrow outgrowth 

dendrite 

• short, branchlike appendages that detect chemical signals from neighboring neurons 

• incoming signals can be excitatory (make the neuron fire) or inhibitory (keepthe neuron from firing) 

myelin sheath

• fatty material made up of glila cells

• insulates axons to allow for faster movement

• nodes of ranvier- small gaps of exposed axon between segements of the myelin sheath, where action potentials take place 

terminal buttons

tiny bulblike structures at the end of axons that carry the neuron’s message into the synapse

synapse

• chemical connections occur between neurons 

• tiny gap between the axon of the “sending” neuron and the dendrite of the receiving neuron 

The membrane 

• fatty barrier covering the neuron 

• Semi-permeable- some substances can pass throygh through

Ion channels

• located along the membrane 

• allows ions to enter 

• charge inside is more negative than outside 

• regulates concentration of electrically charged molecules 

Action potential (neuron firing)

• If a neuron is stimulated beyond a certain threshold, it will “fire”

• strong stimulus → more neurons fired and more often (does not affect the action potentials’ strength or speed firing is all or none) 

• When a neuron “fires,” electrochemical changes occur within the cell 

• causes gates in the membrane to open, allowing positively charged molecules to rush in 

all or nothing principle

• a neuron fires or does not fire 

• same potency each time 

• strength determines by how often a neuron fires 

• stronger= more action potentials 

neurotransmitters 

• convey signals across the synapse 

• same potency each time 

• SamChemicals that are made in the axon and stored in vesicles 

presynaptic neuron

sends info

postsynaptic neuron

receives info

excitatory neurotransmitters

increases likelihood of firing

inhibitory

decreases likelihood of firing