lecture 23 Flashcards
nervous system
how can you classify nervos tissue anatomically?
CNS (brain, cerebellum, spinal cord – gray matter and white matter) vs PNS (nerve ganglia, nerve fibers)
can can you classfiy nervous tissue histologically?
neurons vs neroglia (glial cells equivalent to CT so for suport, protection, defence and nutrition)
describe the structure of a neurons and general functions of each section
- dendrites: receive signals
- cell body: integrate incoming signals from dendrites and outgoing signals to axons
- axons: transmits signal to another neuron or effector cell
what structures are found in the cell body of a typical neuron?
- nissl bodies: has rER and free ribosomes
- axon hilock
- lipofuscin
what are different shapes/polarities of neurons?
- pyrimidal
- purkinje
- motor neurons
- pseudo-unipolar
- bipolar
the CNS consists of what organs?
cerebrum, cerebellum, spinal cord
what does the gray matter contain?
neuronal cell bodies and neuroglial cells
what does the white matter contain?
axons and neuroglial cells (appears white due to presence of myelin)
function of the cerebrum
- integration of sensory information
- initiation of voluntary motor responses
what are the most prominent cells in the cerebrum? how are they organized?
- pyrimidal cells
- arranged in parallel with each other
what is the function of the cerebellum?
- integration of sensory information
- fine-tunes voluntray motor reponses
how many layers are present in the cerebrum?
6 layers
what are the layers of the cerebellum gray matter?
- molecular layer: sparse neurons
- purkinje layer: very large neurons, dendrites project into the molecular layer, axons project into the granular layer
- granular layer: very small, densely-packed neurons, axons are unmyelinated and project into the molecular layer where they synapse with dendrites of purkinje cells
function of the spinal cord
- relay messages from the brain to the body
- pass sensory information from sensory receptors to the brain
- coordinate reflexes that are managed by the spinal cored alone
what are the subdivisions of the PNS and their functions?
somatic:
* sensory nerve fibers that send sensory information to the CNS
* motor nerve fibers that project from the CNS to skeletal muscle
autonomic:
* controls the smooth muscle of the internal organs and glands
what makes the myelin sheath?
- oligodendrocytes in the CNS
- Schwann cells in the PNS
function of myelination
- electrical insulation
- faster conduction of nerve impulse
what are Nodes of Ranvier?
gaps in the myelin sheath that promote transmission of the action potential
what is the myelin sheath composed of?
- several layers of modified cell membrane containing a lipoprotein complex called myelin
- myelin is composed of phospholipids, sphingolipids, and proteins
how many axons are myelinated a schwann cell?
1
how many axons are myelinated a oligodendrocyte?
many
where does an axon begin and end?
begins at the axon hillock and ends in bulbs called terminal boutons, which are part of the synapse
where can synapses form?
- Axon and Dendrite
- Axon and Cell Body
- Axon and Axon
what are the different neuroglia cells?
- astrocytes
- oligodendricytes
- microglia
role of astrocytes
- largest neuroglial cells.Found in the white matter of CNS
- form and maintain the BBB
- remove ions and neurotransmitter remnants such as GABA, glutamate, etc
role of oligodendrocytes
- found in gray and white matter of CNS
- satellite cells around neurons in CNS
- in white matter, these cells produce myelin
role of microglia
- scattered throughout CNS. smallest neuroglial cell, darkley stained, derived from monocytes
- function as phagocytes clearing debris of damaged structures in the CNS
