Neuro Tissue and Organization Flashcards
Towards the CNS (sensory)
Afferent
Exiting the CNS/PNS (motor)
Efferent
Cell body of a neuron
Soma
Something that causes a response
Stimuli
Electric polarization of a nerve cell (electrical current)
Action potential
Projection or outgrowth of tissue from a larger body
Process
Two divisions of the nervous system
Central Nervous System (CNS)-brain and spinal cord
Peripheral Nervous System (PNS) is nerves and ganglia
The signal must be detected and converted somehow into neuronal activity
Transduction
Anatomical division of the spinal cord
Central-brain and spinal cord
Peripheral-cranial nerves, spinal `nerves, ganglia
Nervous system functions include:
Sensory perception, integration and motor planning
Vision requires light from a visual scene to be ____ into a neural activity
Transduced
The information in a signal must be processed and represented somehow by the transduced neuronal activity
Coding
Divisions of the anatomical nervous system
Central: Brain and spinal cord
Peripheral: cranial nerves, spinal nerves ganglia
Muscle contraction is almost always initiated by the activity of the ____.
Nervous system
Synapses of motor neurons onto muscle cells=
the neuromuscular junction
General somatic senses
General or “widespread” receptors spread throughout the body. Receptors include: touch, pain, vibration, pressure, temperature
Type of somatic sense that detects stretch in tendons and muscle. Responsible for body sense-position and movement of body in space
Proprioceptive senses
Hearing, balance, vision and smell are types of ____ senses
Special somatic senses
Somatic (sensory and motor) and visceral (sensory and motor) are part of the _____
Peripheral nervous system
General visceral senses include
Stretch, pain, temperature, nausea and hunger
General visceral senses are widely felt where:
Digestive and urinary tracts, and reproductive organs
Special visceral senses include
Taste and smell
What division of the nervous system signals contraction of the skeletal muscles?
Somatic motor
Somatic motor is also the -
voluntary nervous system
What regulates the contraction of smooth and cardiac muscle and controls function of visceral organs
Visceral motor
Visceral motor is also known as a) and b)
Involuntary nervous system
Autonomic nervous system
What nervous system cells conduct nerve impulses from one part of the body to another?
Neurons
Nervous system cells that have a ___metabolic rate-need lots of ____ and ____
How long do they last?
They are mitotic or non-mitotic?
High, glucose and oxygen
Have extreme longevity
non-mitotic
Glial cells are
Large or small?
mitotic or non-mitotic
Raison d-etre?
Smaller than neuron cells
Mitotic
No nerve impulses but protect and nourish neurons
Fundamental physiological properties of neurons?
Excitability (irritability)-can respond to stimuli
Conductivity-can send signals to distant locations quickly
Secretion-can release chemical messengers (neurotransmitters)
Functional classes of neurons
Sensory (afferent) neurons
Interneurons
Motor (efferent) neurons
What type of neurons detect stimuli
Sensory (afferent) neurons
What type of neurons integrate and process information from other neurons and make decisions about response
Interneurons
What type of neurons send signals to muscles/glands to provide response?
Motor (efferent) neurons
Interneurons are confined to the _____
CNS
What is the control center of a neuron?
Soma or cell body
Unique to neurons, granular bodies found in the soma. Also, the site of protein synthesis
Nissl bodies
Short processes off the cell body that receive signals
Dendrites
long process off the cell body through which a neuron sends action potentials
Axon
Complex branches at axon’s distal end
Terminal arborization (terminal branching)
Ending of an axon branch that communicates with another cells
Axon terminal or axon bouton
Triangular narrow portion of a cell body where axon begins. Action potentials generated here
Axon hillock
At the end of each terminal branch is an ____
axon terminal
The variation in a neuron structured is named by ____
The number of processes leaving the soma
Variations in a neuron structure
Multipolar: many dendrites, one axon (many processes)
Bipolar-one dendrite, one axon (2 processes)
Unipolar-no dendrites, one axon (one process)
Neurohistology-what do neurons look like?
Large, diffuse nucleus with dark, central nucleolus
Nissl bodie (RER)s may be visible as dark granules
Processes off the body-axons and dendrites
Meeting point of a neuron and other cells
Synapse
The presynaptic neuron can secret neurotransmitters that can either ___ or ___ the postsynaptic neuron
Excite, inhibit
Axon to dendrite synapse
Axodendritic synapses
Axon to soma synapse
Axosomatic synapses
Axon to axon synapse
Axoaxonic synapses
A junction between neurons may contain many synapses due to _____ and the presence of multiple ______
Terminal arborization, dendrites
Most neurons have a huge amount of presynaptic partners
10^3-10^4
Two varieties of synapses
Electrical synapses and chemical synapses
Type of synapse where there is a physical connection between the cytoplasm of the two neurons-relatively rare
Electrical synapses
Small gaps between neurons across which chemical messengers (neurotransmitters) diffuse
Chemical synapses
In an electrical synapses adjacent cells are joined by____
___ diffuse from cell to cell
Quick transmission
____transmission of electrical signal
Gap junctions
Ions
Simple, Sacrifice specificity for speed
presynaptic neuron releases neurotransmitter to a postsynaptic cell. The release is triggered by ____ arriving at axon terminal.
Action potential
Messenger molecules. Can be both excitatory and inhibitory
Neurotransmitters
What is a structure at a synapse that contains synaptic vesicles -packets of neurotransmitters
Axon terminal of a presynaptic cell
Structures at synapse
Axon terminal of presynaptic cell
Synaptic cleft
Neurotransmitter receptors on postsynaptic cell
Most synapses are _____ synapses
Chemical
Neurotransmitter that is responsible for feelings of well-being. Decrease in this neurotransmitter is a cause for depression
Serotonin
Neurotransmitter that is responsible for feelings of enjoyment and reinforcement, also motor inhibition
Dopamine
Describe the simplest possible circuit
One sensory neuron that synapses on to one motor neuron
More complex behaviors require more complex circuits involving ____-neurons that locally process information and send final decision to effector neurons
Interneurons
99% of the nervous system is _____
Interneurons
Neural circuit where one fiber synapses with several postsynaptic cells
Diverging
Neural circuit where several presynaptic cells converge on a single nerve fiber (i.e. the brainstem receives signals from multiple organ systems)
Converging
Neural circuit that is non-linear. Often involve negative feedback loops
Reverberating
Neural circuit where output neuron receives signals overtime based on the number of interneurons
Parallel after discharge
Type of neuron processing where neurons pass a signal to a specific destination along a single pathway from one to another
Serial processing
Type of neuron processing where input is delivered along many pathways; a single sensory stimulus results in multiple perceptions
Parallel processing
Types of neural processing
Serial processing
Parallel processing
Types of neural circuits
Diverging
Converging
Reverberating
Parallel after discharge
What type of neural processing is associated with higer order functioning?
Parallel processing
Neurons can be classified by their functions. What are the associated functions?
Sensory neurons-a
Motor neurons-b
Interneurons-c
A) Afferent neurons
B) Efferent neurons
C) Association neurons (connect neurons, sometimes sensory to motor)
Sensory neurons are mostly:
Multipolar or unipolar?
Cell bodies found in ganglia (inside or outside) spinal cord
Unipolar
Outside
Motor neurons are mostly:
Multipolar or unipolar?
Cell bodies (inside or outside) spinal cord
Multipolar
Inside
Interneurons are located where?
Entirely within the CNS
Glial cells outnumber neurons ____
10-1
Are glial cells in the CNS and PNS the same?
No
Glial cells do or do not transmit signals
Do not
Glial cells perform what type of functions?
Many metabolic/support functions for neurons
Types of central nervous system glial cells
Oligodendrocytes
Ependymal cells
Microglial cells
Astrocytes
Types of peripheral nervous system cells
Schwaan cells
Satellite cells
Long processes from oligodendrocytes membranes wrap around neuronal axons to help _____
Make impulses travel faster
The oligodendrocytes wrapping around neuronal axons is called the _____
Myelin sheath
Cells that resemble cuboidal epithelial cells that line the fluid filled cavities in the brain and spinal cord
Ependymal cells
Do ependymal cells have a basement membrane?
No
Ependymal cells produce_____
Cerebrospinal fluid (CSF)
What part of the ependymal cells help circulate CSF?
Apical cilia
Cells that perform immune functions in the CNS by phagocytizing pathogens from dead tissue?
Microglial cells
What cells develop white blood cells involved in immune response?
Microglial cells
What cell is a star like shape?
Astrocytes
Astrocytes are most abudent where?
The CNS
Functions of astrocytes
Support nervous tissue
Forms the blood-brain barrier
Selective passage of molecules necessary for neuron function
How do astrocytes form the blood-brain barrier?
Astrocytes projections wrap around capillaries to limited unwanted substances from reaching the neuron
What does the blood brain barrier (BBB) do?
Prevents immune cells, proteins and charged molecules from entering the brain
Helps protect our brain from chemical compounds/inflammation/infection
What type of cells surround the soma in the ganglia and organize waste/nutrient exchange?
Satellite cells (PNS)
What type of cells surround axons with extensions of their plasma membranes to help nerve impulses travel faster?
Swhwann Cells (PNS)
Swhwann Cells (PNS) are analogous to ____ because they produce a myelin sheath
Oligodendrocytes
What is a fatty covering on axons that insulates the wires?
Myelin sheaths
Myelination increases ______ allowing action potentials to_____
Membrane resistance
Propagate faster
Swhwann Cells make myelin in the ____
Oligodendrocytes make myelin in the ____
PNS
CNS
Swhwann Cells extend their _____ to wrap around axons
Plasma membranes
Myelin sheaths are mostly ____
Lipids
Myelin sheaths appear ____ on cadaver. Called ____ matter.
Why does it appear this way?
White, white
Coiling gives white color
Fiber segment covered by myelin
Internodes
Nerve segment lacking myelin
Nodes of Ranvier
Impulse travels along axon and is only exposed at ____
Nodes of Ranvier
Unmyelinated PNS axons are also surrounded by Schwann cells, but Schwann cells do not ____
coil densely around these axons
This is called ____ matter
Grey matter.
A nerve impulse rests on the axon membrane and as a ___ charge
negative
As a nerve impulse travels along the axon, the membrane goes from a ____ charge to a ____ charge. Then the membrane behind the impulse returns to a ____ charge
Negative
Positive
Negative
