Alliyah Evangelista-
What are the general functions of the nervous system?
Control of body functions and regulation of homeostasis.
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Which chemical is used by both the nervous and endocrine systems?
Epinephrine
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Where are the sensory receptors located and what are they?
Skin: Meissner's corpuscle for touch and Pacinian corpuscle for pressure
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What are the effectors of the SNS and what kind of control do we have over them?
Effectors: skeletal muscles
Voluntary control
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What is in the ANS?
- Sympathetic (fight or flight)
- Parasympathetic (feed and relax)
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What are the effectors of the ANS and what kind of control do we have over them?
Effectors: Smooth & cardiac muscle
Involuntary control
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What is the sensory (afferent) function?
- detects change
- sensed by the special and general senses
- sensory neurons send signals to CNS
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What does the integrative function do?
It analyzes the sensory input and stores info. (memory) for future if it happens again; decides the response.
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What is the motor (efferent) function, what are the effectors?
It is the "motor output", responds to change. Muscles and glands are effectors; motor neurons send info. to the effectors. Think "exits the brain/spinal cord".
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Do neurons undergo mitosis?
No, they stay in the G0 phase.
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Label the parts.
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___ is the cytoskeleton of the neuron.
Neurofibrils
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Neurotransmitters are made in the ___.
nissl bodies
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What are myelin sheaths made of and what do they do?
They provide insulation which increases the speed of electrical conduction. They are made of lipids and proteins.
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What do axons do?
They direct signals from the cell body towards the next neuron or the effector.
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Myelin sheath gap is also called ___.
nodes of ranvier
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Describe the direction of nerve impulse conduction.
Dendrites > Cell body > Axon > Axon terminal > Synaptic end bulbs
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Describe multipolar neurons.
Many dendrites, one axon, is the most numerous and part of the CNS.
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Describe bipolar neurons.
Found in the special senses, one axon and dendrite.
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Describe unipolar neurons.
Axon and dendrites at opposite ends; found in the receptors of touch.
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What kind of neuron is this and where can it be found?
Unipolar; receptors of touch.
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What kind of neuron is this and where can it be found?
Bipolar; in the special senses.
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What kind of neuron is this and where can it be found?
Multipolar; CNS, mostly the brain.
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Regardless of structural type, the direction of nerve impulse conduction is always the same. True or false.
True
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Describe the diagram.
Stimuli is picked up by sensory receptor in PNS > impulse travels through the sensory neuron > exits the neuron through the synapse > enters multipolar neuron (CNS) > analyzed by interneuron and is given instrunctions >exits the first multipolar to go the next > stimuli enters PNS again and it travels through a motor neuron > goes to the effectors
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What do neuroglia do?
Supports neurons by protecting and nourishing them (nerve glue).
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Of these two which undergo mitosis: neuron, neuroglia
- neuroglia
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What do astrocytes do?
They form a blood brain barrier to protect neurons.
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What do oligodendrocytes do?
Produce a layer of myelin sheath around axons and several neurons in CNS.
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What is the function of ependymal cells?
They secrete cerebrospinal fluid (CSF)
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What do the schwann cells do?
- wraps several layers of myelin sheath around a single axon in PNS
- creates myelin sheaths, thus electrically insulating axon
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What is myelin made of and cells make them?
Oligodendrocytes in the CNS or schwann cells (PNS); composed of lipids and proteins.
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What does the myelin sheath do?
Electrically insulate the axon; increases the speed of conduction.
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In the PNS, some neuron regeneration is possible. How?
This only occurs if the neurolemma is intact.
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What is inside white matter and what gives it its colour?
Mainly myelinated axons of many neurons; the fat of the myelin give it its white colour.
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What is gray matter made of?
Neuron cell bodies, unmyelinated axons, dendrites and more.
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What is the collection of neuron cell bodies in the CNS and the PNS called?
CNS - nucleus
PNS - ganglion
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How do excitable cells communicate with one another?
Graded potential (GP) - communication over local, short distances in neurons only
Action potentials (AP) - long or short distances in neurons and motor cells
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What is the intracellular voltage/RMP of the cell?
-70mV
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What hormone allows ligand-gated channels to open?
Acetylcholine
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Polarity is the result of ___.
a difference in the electrical charge across the membrane (3Na+ out for every 2K+ coming in).
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What causes an action potential?
When stimuli reaches the threshold level (-55mV).
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Depolarization promotes AP production. True or false.
True; depolarization increases the positive ions in the membrane, thus making the potential less negative. Channels open up along the axon (as a result of a stimulus) for positive ions to enter the membrane.
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In a GP, what causes it to trigger an AP?
When they add together to become larger.
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What is the all or one principle?
AP can only occur if the mp reaches the threshold (-55).
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What happens when the mp reaches +30?
K+ starts leaving the membrane, repolarization occurs.
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Describe the RMP.
High intracellular Na; high intracellular K.
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AP travelling from the trigger zone to the axon terminals is called ___.
propagation
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AP dies out. True or false.
False; they keep their strength as they spread across the membrane.
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What is depolarization?
When NA+ channels open, and make the RMP more positive. The first step in creating an AP and reaching the threshold.
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Slow/continunous conduction occurs in what type of axons?
Unmyelinated
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Saltatory conductions occus in what type of axons? It jumps from myelin to myelin, separated by a node of ranvier.
Myelinated
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If excitatory, ___ is produced. If inhibatory ___.
AP, no action AP
