Advertisement Upgrade to remove ads

Central Nervous System

Brain & Spinal Cord

Peripheral Nervous System (PNS)

12 Pairs of cranial nerves, 31 pairs of spinal nerves... the sensory and motor neurons that connect the central nervous system

Somatic Nervous System (SNS)

Voluntary - any skeletal muscle tissue. (contains sensory neurons, voluntary and conciously controlled)

Autonomic Nervous System (ANS)

Involuntary - any SMOOTH muscle etc.(nerves that carry involuntary impulses to smooth muscle, cardiac muscle, and various glands)

Sympathetic Division

"Fight or flight" - prepares for emergency. (the part of the autonomic nervous system that arouses the body to deal with perceived threats)

Parasympathetic Division

"Rest and Digest" - "Feed and Breed" - calms you down. (branch of the autonomic nervous system; it calms and relaxes the body)

Functions of The Nervous System

Orientation of the body and its parts, coordination and control. Assimilation of learning experiences (learning, memory, intelligence), instinctual behavior. (recieve messages, proccess info and responds to stimuli, controls and coordinate body functions)

Cells of the Nervous System

Neurons

Neurons

The structural and functional unit of the nervous system. (individual cells that are the smallest units of the nervous system)

Dendrites

Cytoplasmic Extensions. They collect and carry impulses TOWARD the cell body, have receptors for certain neurotransmitters.

Perikaryon

Cell Body. Contains chromatophilic Nissl bodies (RER), contains most of the organelles, nucleus. Axon Hillock: Connects soma to axon, sums the potential to determine if the axon will fire. Neuron cell body. Eucromatic nucleus, nissl bodies (stacks of rough ER), numerous mitochondria, large perinuclear Golgi apparatus.

Autonomic Nervous System

Sympathetic Division and Parasympathetic Division

Peripheral Nervous System

Somatic Nervous System and Autonomic Nervous System

Structure of a Neuron

Cell body=perikaryon=soma (body), vast # short dendrites, receive signals from environment, singe axon (nerve fiber) arises from axon hillock

Axon

Cytoplasmic Extensions; Carries impulses AWAY from soma (cell body), synaptic knob contains neurotransmitters.

Structural Types of Neurons

Unipolar - Bipolar - Multipolar

Unipolar Neuron

(Fastest) Have a single point of attachment to perikaryon. Sensory: some aggregate into ganglia associated with spinal cord (reflexes). Used for sending signals to the brain quickly.

Axon Hillock

Area where the axon joins the cell body. Portion of the neuron that connects the cell body, soma, to the axon. The impulses the neuron receives from all the dendrites are summed up at the axon hillock to determine whether an action potential will be initiated.

Bipolar Neuron

(Mid-way) Neuron with one dendrite and one axon. Found in eyes, ears, nose. Ex: pathway of vision.

Multipolar

(Slowest) 1 axon, many dendrites. Most common, integration (interneurons).

Types of Neurons

Sensory - Motor - Interneuron

Sensory Neurons

AFFERENT: Carry sensory information from sensory receptors TO the central nervous system.

Motor Neurons

EFFERENT: Carry sensory information FROM central nervous system to muscles and glands.

Interneuron

Relays information from the afferent neurons to the efferent neruons. Found between sensory and motor neurons, integration. (Does the "thinking")

Neuroglial Cells

Helper or Supporter Cells - Responsible for keeping the neurons alive an function at their peek. Cells which support, insulate, and protect neurons.

Neuroglial Cells

Schwann Cells (Myelin Producing)- Oligodendrocytes (Myelin Producing)- Microglia - Astrocytes - Ependymal Cells

Schwann Cells

(PNS) Neurilemmocyte - Produce a myelin sheath around PNS formed by wrapping around axon or dendrite.

Oligodendrocytes

(CNS) (Means Few Branches) Produces a myelin sheath around CNS, formed by wrapping cytoplasmic extensions around multiple axons or dendrites.

Microglia

(CNS) Specialized Phagocytic (immune cells) of the CNS. Cells that protect neurons by engulfing disease causing microorganisms.

Astrocytes

(CNS) Structural support, astrocytes, hold neurons in place, help form Blood Brain Barriers (BBB) and form scar tissue.

Ependymal Cells

(CNS)Line the ventricles, regulates (makes) the cerebral spinal fluid (CFS) composition.

Myelination

Process by which lipid membranes are formed and wrapped around axons in the central and peripheral nervous systems.

Myelin

Electrical insulator of axons and dendrites - White lipoprotein (think plasma membrane) produced by Schwann Cells and Oligodendrites. Increases the speed of the signal conduction by using salutatory (jumping) conduction.

Myelin Sheath

Covers the axon of some neurons and helps speed neural impulses. Comprised of the membranes of the insulating cell.

Neurilemmae

Outermost cell membrane of the Schwann Cell neuroglia.

Node of Ranvier

Gaps between segments in the myelin sheath that allow for conduction.

Steps of Neuronal Regeneration

Neurons are amitotic (if destroyed no repair but if damaged, can be repaired) 1. Axon is severed, everything distal of this will degenerates, particles are phagocytized. 2. Schwann cells regenerate and myelin tube may form. 3. Proximal portion sprouts and attracted to the regeneration tube. 4. Axon grows down and the connection is reformed.

Properties of Neuronal Tissue

Irritability - Conductivity

Irritability

Capable of responding to stimulus.

Conductivity

Can turn a stimulus into electrical impulse or (action potential) AP

Resting Potential

-70mv - Charge maintained by relative levels of anions.The difference in electric charge between the inside and outside of a neuron's cell membrane.

Threshold Potential

-55mv - Charge that must be reached for an AP to occur.

Action Potential

+30mv - Charge that is reached during impulse transmission. The "SPARK"

Depolarization

Increase in voltage toward the AP.Cell becomes less negative i.e. -70 to -55

Repolarization

Decrease in voltage back toward the resting potential.

Hyperpolarization

<-70mv - Decrease in voltage beyond the resting potential.

Steps of Nerve Impulse Conduction

1. Stimulus occurs (must bring cell to threshold potential). 2. Depolarization occurs - VOLTAGE gated Na+ channels open, Na+ rushes in, increasing the intracellular voltage. 3. Action Potential is reached - electrical impulse that travels along the axon; REPOLARIZATION - VOLTAGE gated K+ channels open, K+ EXITS cell, Na+ gates CLOSE, voltage begins to decrease. 4.Hypolarization - Na+/K+ pumps begin to move Na+ OUT of the cell and K+ INTO the cell. 5. This exchange of electrons occurs sequentially along the axon. 6. Refractory Period - absolute vs relative.

Speed of Transmission

Based on many factors: 1. Diameter of fibers 2. Type of Fiber 3. Myelination 4. General Conditions of fibers

Synapse

Junction of a neuron and another neuron. the junction between two neurons (axon-to-dendrite) or between a neuron and a muscle noun
Ex. "nerve impulses cross a synapse through the action of neurotransmitters"

Presynaptic Neuron

Neuron before the synapse, contains synaptic vessicles with neurotransmitters

Set up of the Synapes

Presynaptic Neuron - Synaptic Cleft - Postsynaptic Neuron -

Synaptic Cleft

Gap between the pre and post synaptic neurons.

Postsynaptic Neuron

Neurons following the synapse, location of the receptors of the neurotransmitters.

Types of Postsynaptic Potentials

Excitatory (EPSP) - raises the intracellular voltage TOWARD the threshold. Inhibatory (IPSP) - drives the intracellular voltage further FROM the threshold

Neurotransmitters

Chemical messengers found in the synapese. Ex: ACh, GABA, dopamine, norepinephrine, seratonin

Neuropeptides

Acts as neurotransmitters or neuromodulators.

Neuropeptides

Enkephalins - B-Endorphins - Substance P

Enkephalins

neurotransmitters that regulate how much pain transmissions of slow fibers reach the brain (Pain relievers)

B-Endorphins

Very strong pain reliever (euphoria)

Substance - P

Strong neuropeptides, transmits pain within the spinal cord.

Neuronal Pool

Organized group of neurons with in CNS

Facilitation

Making stimulation of a neuron easier.

Convergence

2 or more presynaptic neurons per 1 post synaptic neuron.

Divergence

1 presynaptic neuron per 2 or more post synaptic neurons.

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set