Reiter 1 Flashcards
- Cerebral/cerebellar hemispheres
- Brain stem
- Spinal cord
CNS
- Nerves
- Nerve ganglia - small aggregates of nerve cells
PNS
________ carry motor information away from the cell body
Efferent nerves
________ carry sensory information to the cell body
Afferent nerves
The Human Nervous System is not complex in terms of the number of cell types, but it is highly complex in terms of ________.
nerve/nerve and glia/nerve interactions
Glial cells outnumber neurons _____.
10:1
Two major classes or cell types
- Neurons or nerve cells
2. Neuroglia or glial cells
• excitable or irritable
• transmit information to other
neurons, muscles or glands through synapses
• Requires a chemical messenger, e.g., norepinephrine, serotonin, etc.
Neurons or nerve cells
• support, protect and nourish neurons
• remove and/or degrade some
neurotransmitters
Neuroglia or glial cells
Receives stimuli
dendrites or cell body
Processes information
cell body
Transmits to
other neurons or
glands
axon
Afferent/sensory
Dendrites
Efferent/motor
Axon
Sensory information must go to ____ before a response can be made
brain
The nervous system detects stimuli from peripheral receptors, such as _______ and _____.
- Special senses (eye, ear, taste, smell etc.)
* Somatic senses (touch, pain, temperature)
The nervous system transmits all stimuli generated by sensory tissues in the _______.
internal and external environment
The perikaryon or soma of the neuron is the _______ for the cell (almost everything the cell synthesizes is produced in soma).
Trophic center
_______ receives stimuli from axons
of other cells (via axodentritic
and axosomatic synapses).
Perikaryon or Soma of Neuron
Perikaryon or Soma of Neuron contains ________ and _______.
– Nucleus with prominent nucleolus (ribosomal RNA)
– Cytoplasm with usual organelles
The ______ is highly metabolically active use abundant oxygen and glucose.
Nucleus of a neuron
• Spherical • Unusually large • Prominent nucleolus • Chromatin is finely dispersed reflecting the intense synthetic activity of these cells (euchromatin predominates)
Nucleus of a neuron
Highly developed, clumps to form Nissl bodies (rough endoplasmic reticulum; protein synthesis)
Rough endoplasmic reticulum of neuron
Accept transport vesicles on cis face and package as secretory vesicles
from trans face
Golgi apparatus of neuron
Synthesize ATP
Mitochondria of neuron
– transport materials
– determine cell shape
– bundle together to form neurofibrils
Neurofilaments (cytoskeletal proteins) of neuron
Neurons have _____ axon(s) that transmit _______ information.
- Only one
- efferent (motor)
Axons originate from the
_______ found
on the perikaryon and vary in length. May _____ to provide the same signal to many cells/effectors
- axon hillock
- branch
Axon potentials pass in ______ direction only.
Anterograde
Primarily motor (efferent) nerve to muscles of facial expression
Facial Nerve (VII)
Most neurons have _____ dendrites.
Many
Dendrites are short and divide like tree branches (arborization); as they divide they become thinner; they transmit ______ information
sensory (afferent)
Dendrites are covered with _______, which represent areas for synapses.
dendritic spines (boutons)
Primarily
sensory (afferent)
nerve from receptors on face and
tooth pulp
Trigeminal nerve (V)
releases synaptic vesicles of neurotransmitters into the synaptic cleft.
Presynaptic membrane
a region of extracellular
space between presynaptic and postsynaptic neurons
Synaptic cleft
receptors for the released neurotransmitter bind the neurotransmitter.
Postsynaptic membrane
neurotransmitter synthesis and release - exocytosis
Pre-synaptic terminal
metabolism and diffusion
of released neurotransmitter
Synaptic cleft
binding of neurotransmitter to receptor and depolarization or hyperpolarization of cell membrane
Post-synaptic neuron (or cell)
Neurotransmitters can be
______ or _______. Neurotransmitters are monoamines, amino acids or small peptides.
excitatory of inhibitory
Microfilaments and microtubules - identical to those found in many other cells except these may be exceptionally long
Neuronal cell processes (dentrites and axons)
_____ and _____ “motors” are used to move molecules and some organelles up and down the nerve ending
microtubule and neurofilament
moves cargo retrograde (toward soma for disposal).
Dynein
moves cargo anterograde (away from soma)
Kinesin
_____ are transferred from the soma to the ends of axons
mitochondria
Some viruses (Herpes) may be transported _______ in peripheral nerves
both retrograde and anterograde
Neuron classification: All motor neurons, interneurons and many sensory neurons
Multipolar neuron
Neuron classification: Common in special senses
Bipolar neuron
Neuron classification: Specialized locations
Unipolar neuron
Neuron classification: Uncommon
Anaxonic neuron
– very long processes – large motor cells • pyramidal cells • Purkinje cells • alpha motor neurons
Golgi type I cells
– very short processes
• Granule cells of cerebellum
Golgi type II cells
The size of the cell body is proportional to _______.
length of axon
______ neurons - control muscle, exocrine and endocrine glands
Motor (efferent)
______ neurons - receive environmental stimuli. Can be specialized, e.g., light, temperature, sound, stretch.
Sensory (afferent)
______ often connect a motor neuron with a sensory neuron.
Interneuron
the connective tissue of the nervous system
Glial cells
• Form a structural framework
• Separate neurons to prevent “crosstalk”
• Control chemical environment
–Remove ions
–Remove neurotransmitters and debris
• Nourish & protect neurons
• Undergo cell division (unlike most neurons)
Glial cells
_____ myelinates 1 segment of an axon in the PNS.
Schwann cell
Peripheral nerves appear white because of _______.
myelination
________ myelinates many neurons within the CNS simultaneously
(forms the white matter).
Oligodendrocyte
_______ the number of wraps of myelin increases the speed of conduction.
Increasing
most myelin – fastest –
used for reflexes
Aalpha
less myelin- slower – used for transmission of sensory information
Abeta fibers
even less myelin – bright pain (acute, intense pain)
Adelta fibers
no myelin – slow pain – chronic aching pain (toothache).
C fibers
myelinated sheath is not continuous but is interrupted at 1 mm intervals called _____.
Nodes of Ranvier
Myelin formation in
CNS = ________
PNS = ________
- oligodendroglia
- Schwann cells
Myelin is rich in _______.
polyunsaturated fatty acids
• Schwann cells (in PNS) and oliogodendroglia (in CNS) wrap around axons (between two nodes
of Ranvier)
• Wrap axon many times to form multiple layers
“Jelly Role” Hypothesis of Myelination
- Foot processes envelop blood vessels – These contribute to the blood- brain barrier (this determines selective permeability)
- When damage occurs to brain, they may form a “glial scar”, that may predispose to epilepsy
Astrocytes
- Mesodermal origin. Thus , they are not true glial cells.
- Macrophage-type cells that phagocytose debris
- Activated microglia may be neurotoxic, e.g. in ALS
- Some evidence that they can surround neurons and destroy synapses in autism.
Microglia
Microglia are wandering cells that “________.”
Take out the trash
