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Nervous System C12

Bio 209 Nervous System Ch. 12

What is a nerve? A bundle of 100 to 1000 axons.
What is a mass of neuron cell bodies? Ganglia
Do nerves go around randomly? No. They have a defined path.
Term for sensory portion of system. Afferent
Term for motor portion of system. Efferent
Interactive portion of system. Brain
2 portions of nervous system CNS and PNS
Parts of PNS 1)Somatic (voluntary motor and sensory nerves to skeletal muscles) 2)Autonomic (involuntary M and S to cardiac m., smooth m., and glands) 3)Enteric (involuntary M and S to gastrointestinal system)
2 main types of nervous system cells and how they differ. Neurons (transmit nerve sensations) and Neuroglia (help maintain and nourish neurons, are smaller, and more numerous (10:1), and can multiply and divide)
Where are the nuclei of neurons located? In cell bodies in the CNS
How fast are neuron signals transmitted? 280 mph (milliseconds)
Short branches of nuclear portion of neuron and what they do. Dendrites talk to and receive transmitted messages from other neurons.
Long portion of neuron axon
substance wrapped around axons in PNS Schwann cells
Space between myelin sheeths nodes of Ranvier
At the non-nuclear end of neurons axon terminals and synaptic end bulbs
Where is neuron nourishment found? Electrolytes, minerals, etc. move in space under sheath of axon.
Two ways neuron nourishment moves. Fast (200-400mm/day in both directions for recycling and maintenance of axon) and Slow (1.5mm/day in one direction for growth and repair)
Structural classification of neurons Multipolar (only in CNS), Bipolar (in senses-ears, eyes, nose...), and Unipolar (motor and all other)
Just name the 6 types of neuroglia. Astrocytes, Oligodendrocytes, microglia, ependymal cells, Schwann cells, and satellite cells.
Which 2 neuroglia are only found in the PNS and what are their function? Schwann cells (myelinate single axons. nucleus on periphery) and satellite cells (surround cell bodies of neurons and regulate the exchange of materials between the cell and extracellular fluid)
Which neuroglia make fluid? Where are they found? Ependymal cells make CSF and are found around the ventricles of the brain and the central canal of the spinal cord.
Which neurglia cleans up CNS? Microglia are phagocytes and clean up with phagocytosis.
Which cells myelinate the CNS? Oligodendrocytes form and maintain the myelin sheath of several axons at a time. Have some nodes of Ranvier, but fewer than neurons.
Which neuroglia increase in prevalance as a human reaches maturity? oligodendrocytes
What is the function of "star cells?" Astrocytes support neurons, regulate their interaction and their environment, and make up the blood-brain barrier (screening chemicals btwn blood and brain tissue).
What are the two types of "star cells?" 1)Protoplasmic (in gray matter, short and branching) 2)Fibrous (in white matter, long and unbranched)
What is the function of the myelin sheath? Speeds impulse conduction and reduces area of neuron membrane that must be kept charged.
2 types of conduction through axon. Saltatory conduction (which myelin sheaths) and continuous conduction (slow).
Disease that destroys myelin. MS
Unmyelinated matter vs. myelinated matter Gray matter versus white matter (white because of fatty myelin)
Tube an axon must go through in the PNS. Neurolemma
What happens if tube around an axon doesn't regenerate completely before axon growth? Axon may start spiraling, forming a lump.
Gray and white matter layers in brain vs spinal cord. Brain has gray over white. Spinal cord has white over gray.
2 ways neurons communicate with one another(potentials). Graded (btw. short distances) and Action (btw. short or long distances)
Types of ion channels in nerves. 1)Leakage (Na+andK+) 2)Voltage gated (charge, millivolts) 3)Ligand gated (chemical, neurotransmitter) 4)Mechanical gated (pressure, vibration, stretch...Common in senses like auditory and touch receptors)
Resting membrane potential voltage. -70mV
Threshhold of a nerve -55mV
Max voltage of a nerve action potential around 32mV
Graded potentials usually employ what ion channels? Ligand or mechanically gated channels.
Senses communicate with what type of electrical signals using what ion channels? Why is this important in our perception? Mechanical gated channels during a graded potential. There is no refractory period, so there is no time period we can not receive a stimulus. Also, they can vary in amplitude depending on amt of channels open or closed.
Phases of producing an action potential. Resting, Depolarization (- to + voltage), repolarization (+ to - v), and refractory period.
While graded potentials can vary in amplitude, action potentials what? All Or Nothing Principle. Once -55mV is reached, action potential will continue.
What ion enters cell during depolarization? Na
What ion leaves cell to repolarize it? K
How does the length of an axon affect its action potential? Longer nerves have less of a refractory period (like sciatic nerve)
Axon diameter classification of nerves A Fibers (largest, myelinated, mainly to skeletal muscle, some to senses. ex-sciatic). B Fibers (middles size, myelinated, mainly in autonomic nervous system). C Fiber (smalles, unmyelinated, sensory and viscera)
Subtypes of autonomic nervous system (PNS) Sympathetic and parasympathetic
Nerve at synapse closest to CNS vs further from CNS Presynaptic neuron vs postsynaptic neuron
Types of synapses Chemical (neurotransmitters that either stop or start action) and Electrical (action potentials- for smooth m., cardiac m., embryo, and CNS because it is usually faster and synchronized (heart beat)
Why can't neurons repair after damage in the CNS? The cell bodies containing the nuclei are in the CNS and nerves can't repair once nuclei are destroyed.
Fancy name for the axon dying in side distal to the nucleus. Wallerian Degeneration
Just name 6 different types of neurotransmitters. Amino acids, ACh, ATP + purines, Noxide, Biogenic Amines, Neuropeptides.
Disease with low dopamine. Parkinson's D.
Disease with high dopamine. Schizophrenia
Amino acids act as neurotransmitters where? 3 examples. Inhibits and excites CNS. Glutamate (excites), GABA (inhibits-in sleeping pills), and Glycine (inhibits)
Where is ACh a neurotransmitter? Inhibits and excites CNS and PNS
What do ATP and Purines do? Excite CNS and PNS
What does Noxide do? Formed on demand from brain and reacts quickly and is quite toxic. It relaxes arterial walls (lowers BP)so used as heart attack medication. Also used in brain for memory and learning.
Where are biogenic amines neurotransmitters? What is there chemical make-up? Excite and inhibit CNS and PNS. Amino acid minus -COH
4 examples of biogenic amine neurotransmitters and what they do. 1)Epinephrine (small amts in brain) 2)Norepinephrine (in brain for awakening from deep sleep, mood, and dreaming) 3)Dopamine (Emotional responses, addictive behaviors, pleasure, muscle tone,+ mvmnt) 4)Serotonin (T reg, perception, mood, sleep, appetite)
Neurotransmitter dealing with pain. How do they transmit and what is their chemical make-up? Neuropeptides are amino acids bound together by peptide bonds. They excite and inhibit. Only transmit from head down axon.
4 examples of neurotransmitters pain related. 4 Neuropeptides 1)Enkephalins (200x stronger than morphine for pain reduction) 2)Endorphins (pain killers) 3)Dynorphins (pain killers) 4)Substance P (transmits pain)
Study Cranial Nerves
Created by: 741879016