3.2 Discovery of How Neurons Function
Neurons- cells in the nervous system that communicate with one another to perform
Santiago Ramón y Cajal- used a staining technique invented by Camillo Golgi, to
determine the structure of a neuron. He determined that neurons are the information-
processing units of the brain and that even though he saw gaps between neurons, they had
to communicate in some way ,
3.3 Components of the Neuron
Cajal discovered that neurons are complex structures composed of three basic parts: the
cell body, the dendrites, and the axon.
Cell body- the largest component of the neuron that coordinates the information-
processing tasks and keeps the cell alive. (metabolism, protein synthesis occur here)
Neurons have a nucleus and cell membrane and two specialized extensions of the cell
membrane a axon and dendrite.
Dendrites- receive information from other neurons and relay it to the cell body.
axon- transmits information to other neurons, muscles, or glands.
the axon is covered by a myelin sheath (an insulating layer of fatty material.). Which are
made of glial cells, which are support cells found in the nervous system.
synapse: the junction or region between the axon of one neuron and the dendrites or cell
body of another.
3.4,3.5 Major Types of Neurons
Sensory neurons receive information from the external world and convey this information
to the brain via the spinal cord.(Specialized endings receive signal for light)
Motor neurons carry signals from the spinal cord to the muscles to produce movement.
Interneurons, which connect sensory neurons, motor neurons, or other interneurons.
( Makes up most neurons, identifys location of sensory signal, recognize familiar faces)
Neurons are also somewhat specialized depending on their location.
(The Purkinje cell has an elaborate treelike assemblage of dendrites, carry info from
cellebrium to rest of body.
Pyramidal cells have a triangular cell body and a single, long dendrite with many smaller
dendrites, found in cerebral cortex
Bipolar cells have only one dendrite and a single axon, sensory neuron, retina eyes.
3.7, 3.8 Electric Signaling: Conducting Information within a Neuron
Communication of neurons, two stages= conduction and transmission=electrochemical
action of neurons.
Conduction of an electric signal over relatively long distances within neurons, from the
dendrites, to the cell body, then throughout the axon.
Transmission of electric signals between neurons over the synapse.
Cell membrane of neuron porous= allows ions in
Resting potential, which is the difference in electric charge between the inside and outside
of a neuron’s cell membrane. Natural charge
resting potential arises from the difference in concentrations of ions inside and outside the
neuron’s cell membrane.
resting potential is negative, -70mv. Negative because it's that the membrane is far more
permeable to K+ than it is to Na+ because of leakage channels.
So, Na/K-ATPase pumps K+ into the cell and Na+ out of the cell. Then K+ leaks back out, down its concentration gradient, driving the membrane potential more negativ3
In the resting state, there is a high concentration of a positively charged ion, potassium (K+), as well as negatively
charged protein ions (A−), inside the neuron’s cell membrane compared to outside it. By contrast, there is a high
cell membrane.of postively charged sodium ions (Na+) and negatively charged chloride ions (Cl−) outside the neuron’s
action potential, which is an electric signal that is conducted along the length of a
neuron’s axon to the synapse.
Action potentials are caused by an exchange of ions across the neuron membrane.A
stimulus first causes sodium channels to open. Because there are many more sodium ions
on the outside, and the inside of the neuron is negative re