Nervous Tissue Flashcards
What is Neurobiology?
And what other branches does it include?
Study of the Nervous System
Includes Neuroanatomy and Neurophysiology
What are the Nervous System Functions?
Sensory perception, integration, and motor planning
What does the Central Nervous System include?
Brain and Spinal Cord
What does the Peripheral Nervous System include?
Nerves that branch out of the CNS/Ganglia
Name all the branches and sub-branches of the Nervous System
Actions of the Viseral Sensory Division
DETECTS signals from the visera of thoracic and abdominal cavites
Actions of the Somatic Sensory Division
DETECTS signals from receptors in the skin, muscles, bones, and/or joints
Actions of the Viseral Motor Division (VMD)
SENDS signals to glands, cardiac muscles, and/or smooth muscles
What do the Sympathetic and Parasympathetic Divisions do?
Sympathetic Division: Battle mode, prepares the body for extreme situations (fight or flight mode)
Parasympathetic Division: conducts normal bodily functions when the body is at a regular state
Actions of the Somatic Motor Division
SENDS signals to skeletal muscles, many of which are in voluntary control
What is a Nervous Cell and its properties?
Neuron, carries out system communication of the body
Properties:
Excitability: irritablity, response to stimuli via electrial signals
Conductivity: sends signals to distant locations quickly due to electrical response to stimuli
Secretion: secreting neurotransmitters/chemcial messegers when electrical signals reach the end of nerve fibers
Sensory Neuron Action
Afferent Neurons
Detect stimuli
Interneuron Action
Receive signals from other neurons and make response decisions
Motor Neuron Action
Efferent Neurons
Sends response signals to muscles
What is a Neurosoma?
Control center of a neuron
(soma or cell body)
What are Chromatophilic Substances?
Compartmentalized Rough Endoplasmic Recticulum
What are Dendrites?
Receives signals and messages from other neurons
(# of dendrites vary)
What do Axons do?
Describe what are terminal arborizations and axon terminals
Sends action potentials
Terminal Arborizations: Complex of branches at axons distal end
Axon Terminal: ending of an axon branch that communicates with another cell (makes synapses)
Cells of the Neuroglia of the Central Nervous System
CNS glia includes:
Oligodendrocytes, mircogila, ependymal cells, and astrocytes
What do C.O.P.S stand for?
CNS
Oligodendrocytes: make myelin for the brain and spinal cord
PNS
Schwann Cells: form myelin in the peripheral nervous system
Ependymal Cells
CNS
Secrete and circulate cerebrospinal fluid that line internal cavites of the brain and spinal cord
Microgilia Cells
CNS
Macrophages that eat microorganisms, dead tissue, and foreign matter
(help in defense and disposal)
Astrocytes
Gives support and nourishment for the CNS
Schwann Cells
Produce myelin sheath and regenerates damaged fibers of the PNS
Satellite Cells
Support and nourish the gangila and PNS
Myelin
An insulating layer or sheath that forms around nerves
Myelination
Formation of a myelin sheet
Describe a Ganglion
Concentration of cell bodies in the PNS
Whats another name for the Autonomic Nervous System?
What are it’s subdivisions?
The Visceral Motor System
Subdivisions:
- Sympathetic Division
- Parasympathetic Division
Source of new neurons in the CNS
Mitosis of existing neurons
Axon Hillock
mound located on one side of the soma from which the axon originates
Multipolar Neurons
Many Dendrites, one axon
(Most neurons are this!)
Bipolar Neurons
One dendrite, one axon
(rare neurons)
Unipolar
No dendrites, one axon
(starts out as bipolar neurons)
Anaxonic Neurons
Many dendrites but no axon
(No axon = no action potentials made)
Neurilemma
Outermost layer of myelin, containing the nucleus and cytoplasm of the Schwann cell
Internodal Segment
fiber segment covered by myelin.
Myelin Sheath Gaps
(Nodes of Ranvier)
fiber segment between gaps in myelin
2 factors that influence speed of nerve signal conduction
- Diameter of fiber (larger is faster)
- Presence of myelin (Myelinated is faster)
Fastest fibers are both large and myelinated
What is the Neurilemma?
Outermost layer of myelin of Schwann cells
Contains nucleus and cytoplasm of Schwann cell
Where are unmyelinated nerve fibers found?
Found in both CNS and PNS
Unmyelinated fibers can be found within Schwann Cells
How does the PNS regenerate its nerves?
Neurolemma and endoneurium produce regeneration tube to repair axon
Only if PNS cell bodies are intact
How does the CNS regenerate its nerves?
It can’t
Brain and spinal nerves cannot regenerate
What are synapses?
Meeting point of a neuron and another cell
Presynaptic neuron to postsynaptic neuron
What kind of messages do synapses use?
Both eletrical signals and chemical messagers (neurotransmitters)
What are the two types of synapses and the one variant?
Axodendritic Synapse:
Axon to dendrite
Axosomatic Synapse:
Axon to Neurosoma
Variant synapse is axoaxonic synapse (axon to axon)
How do chemical synapses work?
Presynaptic neuron attaches and releases neurotransmitters to postsynaptic cell receptors
Describe axon terminals of presynaptic cells and synaptic clefts.
When both combined, what do they make?
Axon terminal of presynaptic cell:
contains synaptic vesicles containing neurotransmitters (ex. ACh)
Synaptic Cleft:
Neurotransmitter receptors on postsynaptic cell
Both structures make a chemical synapse
Describe features of electrial synapses
- Joined via gap junctions
- ions diffusing from cell to cell
- very quick transmission to detect stimuli, no descion making response can be made
- can travel in either direction
Describe Diverging Circuits
One input nerve fiber branches out and synapses with several post-synaptic cells
(one input can cause multiple output responses)
Describe Converging Circuits
Contrast to divergent circuits, outputs of many different sources is funnelled to output circuit
Describe Reverberating Circuits
Neurons stimulating each other in sequence causing repetition
Describe Parrallel After-Discharge Circuits
Input neuron diverges and stimulates several chains of neurons that eventually reconverge to the same output neuron
Output neuron recieves serveral signals from multiple pathways
