What are the two organ systems and what do they do?
Nervous and Endocrine systems and they coordinate and direct the activities of other organ systems.
What the Nervous System provide?
it provides swift, brief responses to stimuli; the endocrine system adjusts metabolic operations and directs long-term changes.
What does the nervous system encompass?
It encompasses the neural Tissue in the body
What are the anatomical Subdivisions?
The Central Nervous System and Peripheral Nervous System.
The nervous system is subdivided into what?
The Afferent Division and Efferent Division
What is the Afferent Division?
It Transmits sensory information from the somatic and visceral receptors to the CNS.
What is the Efferent Division?
It carries motor commands to muscle and glands.
The Efferent Division include what two systems?
The Somatic Nervous System(SNS) and the Autonomic Nervous System(ANS).
What are the characteristics of the Somatic Nervous System(SNS)?
Voluntary Control over skeletal muscle contractions.
What are the characteristics of the Autonomic Nervous System(ANS)?
Automatic, involuntary regulation of smooth muscle, cardiac muscle, and glandular activity are under the control of parasympathetic and sympathetic.
Receptors can be classified as what?
Somatic and Visceral.
What are the two types of cells in the neural Tissue?
Neurons and Neuroglia or Glial cells.
What are Neurons responsible for?
They are responsible for information transfer and processing.
What are Neuroglia or Glial Cells?
They are supporting cells in the nervous system
A typical neuron has what?
Cell Body, Axon, and Several Dendrites.
What does an Axon do?
It Carries information in the form of nerve impulses.
What the four types of Neuroglia in the CNS?
1. Astrocytes
2. Oligodendrocytes.
3. Microglia
4. Ependymal Cells
What are Astrocytes?
They are the largest and most numerous glial cells.
What do Astrocytes do?
1. Maintain the blood-brain barrier to isolate the CNS from the general circulation.
2. Provide structural support for the CNS.
3. Regulate ion and nutrient concentrations.
4. Perform repairs to stabilize the tissue and prevent further injury.
Oligodendrocytes do what?
They Wrap CNS axons in a membrane sheath termed myelin.
What are Nodes of Ranvier?
They are gaps between the myeline wrappings along the axon.
What are Internodes?
They are large areas wrapped in myelin.
Regions primarily containing myelinated axons appear glossy white are termed what?
White Matter
What are Microglia?
They are smallest neuralgia cells.
What do Microglia do?
Since Microglia are phagocytic cells they engulf cellular debris, waster products, and pathogens.
When do Microglia increase in number?
They increase in number as a result of infection or injury.
What are Ependymal cells?
They are atypical epithelial cells that line chambers and passageways filled with Cerebrospinal Fluid(CSF) in the brain and spinal cord.
What do Ependymal Cells assist in?
They assist in producing, circulating, and monitoring CSF.
Neuron cell bodies in the PNS are clustered into what?
Ganglia
Neuron cell bodies in the PNS are clustered into ganglia, and their axons form what?
Peripheral Nerves.
What are the PNS glial cells types?
They are Satellite Cells and Schwann Cells.
Satellite cells enclose what?
They enclose neuron cells bodies in ganglia.
What do Schwann cells (neurolemmocytes) do?
They cover all peripheral axon, whether myelinated or unmyelinated.
What is the perikaryon of a neuron?
It is the cytoplasm surrounding the nucleus.
Neurons contains what?
It contains organelles, neurofilaments, neurotubules, and bundles of neurofilaments, termed neurofibrils, which extend into the dendrites axon.
What is an Axon Hillock?
It is a specialized region of an axon.
Neuron connects to the what?
Initial Segment
The Axoplasm is what and contains what?
Axoplasm is the cytoplasm of the axon and contains numerous organelles.
What are collaterals?
They are side branches from an axon.
What is a Telodendria?
They are a series of fine, terminal extensions branching from the axon tip.
Where is a Telodendria located?
Its at the end of the Synaptic Terminals.
What is a Synapse?
It is a site of intercellular communication between a neuron and another cell.
What is a Synaptic Knob?
It is located where one neurons synapses on another.
What are Neurotransmitters?
Synaptic communication usually involves the release of specific chemicals.
Neurons may be classified on the basis of the number for process which are?
1. Anaxonic (No distinguishable axon)
2. Bipolar (One dendrite and one axon)
3. Pseudounipolar (Dendrite and axon are continuous at one side of cell body)
4. Multipolar (Several Dendrites and one axon)
What are the three functional categories of neurons?
Sensory Neurons, Motor Neurons, and Interneurons (association neurons)
What do Sensory Neurons form?
They form the afferent division of the PNS and deliver information from sensory receptors to the CNS.
What are Receptors are categorized by?
1. Exteroceptors
2. Proprioceptors
3. Interoceptors
What are Exteroceptors?
They provide information from external environment
What are Proprioceptors?
They monitor position and movement of joint.
What are interoceptors?
they monitor digestive, respiratory, cardiovascular, urinary, and reproductive systems.
What do Motor Neurons form?
They form the efferent pathways that stimulate or modify the activity of a peripheral tissue, organ, or organ system.
What do the Somatic Motor Neurons Innervate?
The Skeletal Muscle
The Visceral Motor Neurons innervate what?
THey innervate all peripheral effectors other than skeletal muscle.
Axons of visceral motor neurons from the CNS _____________ synapse on neurons in the ganglia; These ganglion cells project axon ___________ control the peripheral effectors.
Preganglionic fiber and postgaglionic fibers.
Where are Interneurons located?
They may be located between sensory and motor neurons.
What do Interneurons do?
They analyze sensory inputs and coordinate motor outputs.
Interneurons are classified as what? Why?
Excitatory or inhibitory on the basis of their effects on post-synaptic neurons.
What is Neural Regeneration?
Neurons have a very limited ability to regenerate, Only a relatively small number of axons within the nerve will successfully reestablish normal synaptic contacts and complete nerve function is impaired permanently.
What is Excitability?
It is the ability of a cell membrane to conduct electrical impulses.
The cell membranes of skeletal muscle fibers and most neurons are excitable. True or False?
True
Changes in the transmembrane potential occur as a result of changes in the flow of sodium and potassium ions are called what?
Action Potentials.
What is a Nerve Impulse?
Its an action potential traveling along an axon.
The rate of impulse depend on what?
On the properties of the axon, specifically the presence or absence of myelin sheath and the diameter of the axon(The larger the diameter, the faster the rate of conduction).
Where do Synapses occur?
1. Dendrites
2. The cell body
3. Along axon
Synapses permit communication between neurons and other cells at the?
Neuroeffector Juctions
What two types of synapse and which one is more common?
It can be chemical or electrical and chemical synapses are more common.
Why is a chemical synapse so special?
Because only presynaptic membrane releases a neurotransmitter, which binds to receptor proteins on the post-synaptic membrane, causing change in the transmembrane potential of receptive cell. Thus, communication can occur only one direction across a synapse; from the presynaptic neuron to the post-synaptic neuron.
Why is Ach important?
Because All neuromuscular junctions utilize Ach as a neurotransmitter; Ach is also released at many chemical synapse in both CNS & PNS.
What are the General Sequence of events at a chemical Synapse?
1. Neurotransmitter membrane
2. the neurotransmitter binds to receptors on the postsynaptic membrane after it diffuses across the synaptic cleft
3. binding of the neurotransmitter causes a change in the permeability of the postsynaptic cell membrane, resulting in either excitatory or inhibitory effects, depending on the identity and abundance of the receptor proteins.
4. The initiation of an action potential depends on the degree of excitation
5. the effects on the postsynaptic membrane fade rapidly as the neurotransmitter molecules are degraded by enzymes.
Where are Electrical synapses found?
They are found between neurons in the CNS and PNS, although they are rare.
What do Electrical Synapses do?
They transmit information more rapidly that chemical synapses.
Roughly 20 billion interneuron can classified into what?
Neuronal Pools.
The neural circuits of neuronal pools may show what?
1. Divergence
2. Convergence
3. Serial Processing
4. Parallel processing
5. Reverberation
What is Divergence?
It is the spread of information from one neuron to several neurons or from one pool to several pools.
What does divergence do?
It facilitate the widespread distribution of a specific input
What is Convergence?
It is the presence of synapses from several neurons on one postsynaptic neuron
What does Convergence do?
It permits the variable control of motor neurons.
What is Serial Processing?
Is a pattern of stepwise information processing, from one neuron to another of from one neuronal pool to the next.
What does Serial Processing do?
This is they way sensory information is relayed between processing centers in the brain
What is Parallel Processing?
It is a pattern that processes information by several neuron or neuronal pools at one time, also many different responses occur at the same time.
What is Reverberation?
It occurs when neural circuits utilize positive feedback to continue the activity of the circuit.
In the CNS, Cell bodies are organized in to what?
Centers
A Center with discrete boundaries is called?
A Nucleus
What is a Neural Cortex?
It is the gray matter that cover portions of the brain.
White matter has bundles of axon are called?
Tracts
Tracts organize into larger units called?
Columns
The centers and tracts that link the brian and the body are?
Pathways
Sensory ________ Pathways carry information from peripheral receptors to the brain; motor ________ pathways extend from CNS centers concerned with motor control to the associated skeletal Muscles.
Ascending; descending
Neuronal cell bodies and axons in both the PNS and CNS are organized into what?
Masses or Bundles with distinct anatomical boundaries.
