The Nervous System: Neural Tissue

The Nervous System: Neural Tissue

1. Organization of the nervous system

1. Functions of the nervous system

1. ______
2. ______
3. ______

1. Two divisions

1. ______Nervous System (CNS) – ______
2. ______Nervous System (PNS) – part of the nervous system ______the CNS

1. ______nerves – carry impulses to & from the ______
2. ______nerves – carry impulses to & from the ______

1. Functional Classification of Neurons

1. ______(afferent) neurons – carry impulses from ______towards the ______

1. ______– sensitive to stimuli that occur ______the body (sense of touch, sight, taste, etc.)
2. ______– respond to stimuli ______the body & monitor changes in the blood, body temp., etc.)

1. ______neurons (interneurons) – lie ______sensory & motor neurons in the CNS and ______incoming & outgoing signals.

1. ______(efferent) neurons – carry impulses ______from the CNS and to effectors (muscles or glands)

1. Two types of Neural Cells

1. ______– carry ______
2. ______cells – ______cells for the neurons

1. ______– ______cells that ______neurons from ______microorganisms.
2. ______– ______cells that connect neurons to ______and help exchange nutrients between capillaries and neurons.
3. ______– cover the fibers of the ______neurons with ______.
4. ______– cover the fibers of the ______neurons with ______.

1. Neuron Structure

1. ______- cell body

1. contains all organelles except centrioles (thus neurons are not able to reproduce)
2. ______– complex rough ER network with many ribosomes.

1. ______– typically shorter processes that convey impulses toward the soma.
2. ______– longer process (up to ______) that conveys signals away from the soma.

1. Each neuron will have only ______axon, however it may be ______.
2. At the end of the axon will be ______(AKA - synaptic knobs or synaptic boutons).
3. Some axons will be covered by white, fatty insulation called a ______. Myelin sheaths increase the speed of impulse transmission.

1)White matter in the brain consists of ______fibers

2)Gray matter consists mainly of ______fibers.

1. The spaces between the myelin sheaths are called ______of ______.

1. Structural Classification of Neurons

1. ______– have a ______process that emerges from the cell body. Functions mainly as an axon for the ______.
2. ______– have ______processes- one axon, one dendrite. Found in the ______of the eye and the ______mucosa.
3. ______– have ______(at least 2) dendrites and one axon. Most ______neuron in the body.

1. Neurophysiology

1. Nerve cells are able to transmit signals due to their properties of

1. ______– responding to a ______
2. ______– able to ______an impulse down its ______

1. The Electrochemical gradient & the Resting Potential

1. The ______for an impulse is supplied by the ______.
2. Neurons create a ______between the ______and the ______of the cell membrane (Potential difference).
3. This chemical imbalance allows the ______charge to travel ______the ______of the ______.
4. ______along the cell membrane, called ______, actively transport ______of the cell & ______the cell.
5. The build-up of Na outside the cell & K inside the cell makes the ______.
6. Because the Na & K ions have different ______, an electrical ______exists between the inside & outside of the cell membrane.
7. The ______of a “charged” or ______axon is ______mV. (The inside is negative relative to the outside)

1. The Acton Potential

1. The transmission of an impulse down the length of an axon is called the ______.
2. A stimulus is applied to a ______membrane, which causes the membrane to become ______to Na.
3. Since there is a high concentration of Na outside the cell, the Na rushes in and changes to ionic differential to a more positive level (about ______mV) called ______.
4. The ______of a membrane at a certain area stimulates neighboring region of the membrane and causes it to depolarize. (This causes a ______down the length of the membrane).
5. The impulse is always the same ______and only ______one way.

1. Repolarization

1. Within ______, the Na gates have ______and K gates have ______to allow for K to flow out of the cell.
2. The loss of K helps to restore the axon to the Resting Potential of –70 mV. (______)
3. The Na/K pumps are then ______to restore normal Na & K levels.

1. Stimuli for Depolarization

1. The minimum stimulus needed to trigger a depolarization and an impulse is called a ______.
2. The ______– _____ – ______says that action potentials will happen completely or not at all.
3. All action potentials are alike no matter the ______of the stimulus.
4. ______of impulse transmission is what separates ______from ______stimulus.
5. Stimuli not strong enough to trigger depolarization are called ______stimuli.
6. Subthreshold stimuli can be ______to cause depolarization.
7. Suprathreshold stimuli trigger only a ______action potential.
8. The ______is the period of time when the Na gates are open & a second stimulus can NOT come down the axon – no matter how strong it is.
9. The ______is the time immediately after the Na gates close and repolarization is still occurring that a exceptionally strong stimulus may cause depolarization.

1. Impulses

1. Impulses travel at different speeds based upon the

1. ______of the axon
2. degree of ______

1. ______axons (which are usually longer as well) carry impulses ______than smaller axons.
2. ______axons carry impulses ______than unmyelinated axons.

1. Myelin sheaths have spaces between them (about 1mm apart) called ______.
2. The current can only be carried at these nodes, thus the impulse has to “______” the myelin sheath. This is called ______.

1. Speed of Impulse Conduction

1. Large, myelinated = ______
2. Medium, lightly myelinated = ______
3. Small, unmyelinated = ______

1. The Synapse

1. Synapse structure

1. ______occur ______the ______of one cell and the ______of the next cell
2. ______– neuron conducting impulses towards the synapse

1. The end of the axon terminates (or ends) in a ______or ______.
2. The knob contains many tiny sacs called ______that contain a ______.

1. ______– neuron conducting impulses away from the synapse

1. The end of the dendrite has a ______membrane.
2. The membrane bears ______.

1. ______– space between the synaptic knob & the receptor membrane______wide
   

1. Synaptic transmission

1. When the impulse reaches the axon terminal (knob), ______of the presynaptic membrane causes ______of the neurotransmitter into the synaptic cleft.
2. The neurotransmitter binds to the ______receptors, which causes Na ion gates to open and local ______to occur.
3. Neurotransmitters – two classes

1. ______: Acetylcholine (______), Norepinephrine, Dopamine, etc.
2. ______: Gamma-aminobutyric acid (______), Glycine, etc.

1. Termination & reabsorption of neurotransmitters

1. The neurotransmitter will continue to ______the receptors as long as they are ______. The neurotransmitters must be ______in one of three ways.

1. Chemical breakdown (______[AChE])
2. ______of the neurotransmitter by the presynaptic membrane
3. ______away from the synapse

1. Neural Disorders

1. ______(MS)

1. ______disorder that ______the myelin sheaths of the axons of the optic nerve, brain, &/or spinal cord.
2. Characterized by ______, ______, ______, and ______coordination problems.
3. It starts at ______, is progressive & there is no ______
   

1. ______

1. ______infection that kills the motor neurons of the spinal cord & brain
2. The dependant motor units become ______and ______.
3. ______programs have all but eliminated this disease.

1. ______

1. ______infection of the ______that is transmitted by ______animals. The virus is absorbed through the ______knob and is carried by the axons up to the CNS.
2. ______symptoms include headache, nausea & muscle pain. ______symptoms include hallucinations, muscle spasms, and difficulty swallowing that cause saliva buildup in the mouth (foaming at the mouth). ______soon follow.
3. ______consists of a series of injections that contain antibodies, which must begin almost ______. W/o treatment, rabies is always ______.

1