Question | Answer |
Major Structures of the Nervous System
Brain | Contains 100 billion neurons |
Major Structures of the Nervous System
Cranial Nerves | Contains 12 pairs of nerves and emerge from the base of the brain. |
Major Structures of the Nervous System
Spinal Cord | Located in the Vertebral(Spinal) cavity |
Major Structures of the Nervous System
Spinal Nerves | Contain 31 pairs of nerves and emerge from the spinal cord |
Major Structures of the Nervous System
Ganglia | Masses of nervous tissue, located outside the brain and spinal cord |
Masses of nervous tissue, located outside the brain and spinal cord
Sensory Receptors | Monitor changes in the internal or external environment |
Types of Peripheral Nerves---Afferent or Sensory Nerve | Is a division of the Peripheral Nervous System(PNS) that forms Action potential and conveys it to the Central Nervous System(CNS)
Body Part----CNS |
Types of Peripheral Nerve---Motor Nerve or Efferent | Is a division of the Peripheral Nervous System(PNS) that conveys Action Potential away from the CNS
CNS-----Body Part |
Subdivision of the PNS(Nerves)
Somatic Subdivision | Sensory and Motor Nerves that connect to the Skeletal Muscle and the Skin. Because its motor responses can be consciously controlled, the action of this part of the PNS is voluntary. |
Subdivision of the PNS(Nerves)
Autonomic Subdivision | Sensory and Motor Nerves that connect to Smooth Muscle, Cardiac Muscle, and Glands. Because its motor responses are not normally under conscious control, the action of the ANS is involuntary |
Parts of a Neuron | Cell Body--The Control Center
Dendrite---The "Receiving" process
Axon---The "Transmitting " Process
Axon Hillock---Beginning of the Axon
Axoplasm----Cytoplasm of the Axon
Axon Terminal---The End of the Axon
Axolemma---The plasma membrane of the Axon
Axon Collateral----Branch of an Axon |
Neuroglial Cell (Know Location and Function of these Cells) | Are located in the CNS and only in the Brain and Spinal Cord and are Astrocyte, Microglia cell, Oligodendrocyte and Ependymal Cell.
Are located in the PNS and are Schwann Cell and Satellite Cell |
Neuroglial Cell---The Astrocyte | Contains microfilament and Supports Neuron
----Provides Safe Nutrients to the neuron
----Helps form the Blood-Brain Barrier
-----Maintains the proper Chemical Environment around the neuron for impulse transmission |
Neuroglial Cell---The Microglial Cell | Is a Phagocyte |
Neuroglial Cell---The Oligodendrocyte | Produces the Myelin Sheath in the CNS |
Neuroglial Cell---The Ependymal Cell | A Single layer of Ciliated Cuboidal or Columnar Cell
----Lines the Ventricles of the Brain and Central Canal of the Spinal Cord
---Secretes and Circulates Cerebrospinal Fluid (CSF) by Filtering Blood Plasma |
Neuroglial Cell --The Satellite Cell | Located in the PNS and Surrounds The Cell Body of the PNS neurons.
---Provides Structural Support
----Regulates the Exchange of Materials between the Neuronal Cell Bodies and the Interstitial Fluid |
Neuroglial Cell---The Schwann Cell | Located in the PNS and Produces The Myelin Sheath in the PNS
----Each Schwann Cell myelinates of a single axon
---Participates in Axon Regeneration |
Myelination | The formation of myelin around the axon
----Each Schwann Cell wraps 1 mm of a single axon
----Spirals many times around the axon |
Nodes of Ranvier | Gaps on the axon where Myelin is absent
Myelin and Nodes of Ranvier Increase the Speed of Electrical Impulses transmission along the axon |
Gray and White Matter in the CNS | Gray Matter is Nervous Tissue that is not Myelinated , which includes Dendrites, Cell Bodies, and Unmyelinated Axons
White Matter is Nervous Tissues that is Heavily Myelinated Myelinated Axons |
Functional Classification of Neurons | Are based on the Direction and type of information transmitted along the axon
There are Three Types:
Sensory Neurons
Interneurons
Motor Neurons |
Functional Classification of Neurons
Sensory Neurons | Sends nerve impulses from sensory receptors in external or internal to the CNS |
Functional Classification of Neurons
Motor Neurons | Sends nerve impulses from the CNS to the Body Parts called Effectors |
Functional Classification of Neurons
Interneuron(Association Neuron) | Relays Information between the Sensory and the Motor Neurons
Located Only in the CNS
The Numbers of interneurons are much More that the sensory or Motor Neurons |
Resting Membrane Potential | Is distribution or negative ions inside and positive ions are outside the membrane
Is a measured by a voltmeter |
Factors that contribute to resting membrane potential(Know in detail for test) | The Na+/K+ pump
Different Permeability of Membrane to Na+, K+, and intracellular anions(Negatively Charged Ions) |
The Na+/K+ Pump | Pumps 3N+ out and 2K+ in every cycle
Each Cycle of pumping adds One More Positive (+) to ECF |
Selective Permeability of Membrane | The number of K+ that leave the cell is more than the number of Na+ that Enters the Cell (refer to the leakage-gated channels)
Intracellular Anons want to leave the cell, but membrane prevents them (most of these anions are part of large proteins) |
Membrane Ion Channels (Factors stimulating the opening of their gates) | The flow of Ions occurs through specifically gated ion channels:
---Leakage Channels
---Mechanically Gated Channels
---Voltage-Gated Channels
---Ligand-Gated Channels |
Membrane Ion Channels
Leakage Channels | Randomly Open and Close
Membrane has More K+ Leakage channel than Na+ Leakage
Channel---membrane is More Permeable to K+ than Na+ |
Membrane Ion Channels
Mechanically Gated Channels | Open and close in response to Mechanical Stimulation such as:Vibration(Sound Wave), pressure, touch, tissue stretching |
Membrane Ion Channels
Voltage-Gated Channels | Open and Close when small Changes in Resting Membrane Potential occurs
Participate in the generation and conduction of Action Potentials/impulses |
Membrane Ion Channels
Ligand-Gated Channels | Opens when a ligand (neurotransmitter) Binds to its Receptor |
The Nerve Impulse | A change in the resting membrane potential
Two Types:
Graded Potential
Action Potential |
The Nerve Impulse
The Graded Potential | Occurs mainly in the Dendrites and Cell Bodies of the Neurons
Useful for Short Communications only
Is short-Lived, eventually dies out
Is weak |
The Nerve Impulse
The Action Potential (Impulse) | Occurs in the axons of the neurons
Useful for Long Distance Communication
Does Not Die Out
Is Strong
Is All-Or- None |
Three Phases of Action Potential
(Depolarization) | Voltage-Gated Na+ Channels Open in the axolemma
Na+ Enter the Neuron
The inside of the neuronal membrane becomes Less Negative and then eventually Positive |
Three Phases of Action Potential
(Repolarization) | Voltage-Gated K+ Channels Open in the axolemma
K+ leaves the neuron
The inside of the neuronal membrane goes From Positive Back to Negative (less positive and more negative) |
Three Phases of Action Potential
(Hyperpolarization) | Voltage-Gated K+ Channels continue to stay open in the axolemma
K+ continues to leave the neuron
The inside of the neuronal membrane becomes More Negative than the resting membrane potential |
Transmitting of the Action Potential | When Ions Na+ Flow in, they may cause Voltage-Gated Na+ channels in Adjacent Segments of the membrane to Open
Positive Feedback
One direction, only toward the axon terminal |
Transmitting of the Action Potential
(Saltatory Conduction) | Occurs on Myelinated Axons
The Voltage-Gated Channels are located Only in the Nodes of Ranvier
Current Jumps from a node of Ranvier to the next node of Ranvier
Is Fast
Less ATP is used |
Transmitting of the Action Potential
(Continuous Conduction) | Occurs on Unmyelinated Axons
Current Flows directly through the membrane all along the length of the axon
Is Slow
More ATP is Used |
The Synapse | Is the place where two neuronal processes meet or where an axon comes into close contact with its target |
Types of Synapse
(Electrical Synapse) | Are presynaptic and postsynaptic cells that are connected by Gap Junction |
Types of Synapse
Chemical Synapse | Are presynaptic and postsynaptic cells that are Separated by Synaptic Cleft(the space that is filled with interstitial fluid) |
Presynaptic Neuron | Sends the signal message |
Postsynaptic Cell | Receives the signal message |
Excitatory and Inhibitory Neurotransmitters | Excitatory: Causes opening Na+ channels in the postsynaptic neuron membrane------depolarization
Inhibitory: Causes opening K+ channels or CL- channels----Hyperpolarization |
Examples of Excitatory and Inhibitory Neurotransmitters | Acetylcholine(ACh)
Excitatory in Neuromuscular Junction
Inhibitory in Parasympathetic Neurons |
Examples of Excitatory and Inhibitory Neurotransmitters | Glutamate: excitatory in CNS:Mood, Level of Consciousness, Learning memory
GABA(Gamma Aminobutyric Acid): Inhibitory in CNS: the Major "Brake" to excitability in the brain
Glycine |