Nervous System Flashcards
What are the 2 divisions of the nervous system?
central nervous system and peripheral nerves system
What are the 2 divisions of the PNS?
sensory/afferent division and motor/efferent division
Describe the sensory/afferent division of the PNS
has sensory receptors that detect stimuli (change in internal or external environments)
Describe the motor/efferent division of the PNS
- nerves convey impulses away from CNS
- innervates (supplies nerves to) effectors = muscles + glands (endocrine or exocrine)
What are the cell types of the nervous system?
- neurons
- neuroglia
What do neurons do? Where are they located?
- they conduct impulses
- make up the CNS and PNS
- mostly amitotic (irreplaceable)
- exceptions for taste, olfaction, and memory
Describe the cell body structure of a neuron
- has typical organelles
- RER called Nissl Bodies
- group//clusters in CNS = nuclei (grey matter)
- groups/clusters in PNS = ganglia
What are the 2 processes from a neurons cell body called?
dendrites and axons
What do dendrites of a neuron do?
they receive incoming messages + relay to cell body
What are the parts of an axon in a neuron? What do they do?
- overall, carry impulses away from cell body
- axon hillock: where axon meets cell body
- axon terminal: typically branched with synaptic end bulbs (enlarged tips)
Axon terminals may be:
1) myelinated: wrapped in many layers of cell membrane from Schwann cells (PNS) or oligodendrocytes (CNS)
2) unmyelinated: no myelin
Describe myelinated axons
- electrical insulation
- gaps in myelin sheath are called Nodes of Ranvier
- myelinated axon bundles in:
- CNS = tracts (white matter)
- PNS = nerves
What do neuroglia (glial cells) do?
support neuron cells = can undergo mitosis (prone to cancer specifically brain tumour)
What are the 2 types of glial cells?
CNS neuroglia and PNS neuroglia
What are the 4 types of CNS neuroglia?
- oligodendrocytes
- microglia
- astrocytes
- ependymal - neural epithelia
What do oligodendrocytes produce? What are they a subtype of?
they produce myelin around axons and are a subtype of CNS neuroglia
What do microglia do? What are they a subtype of?
they are protective, they become phagocytic if detect infected, dead, or damaged neurons (because immune cells can’t enter CNS)
- they are a subtype of CNS neuroglia
What do astrocytes do? Where are they located? What are they a subtype of?
- they surround blood capillaries to form part of blood brain barrier (BBB)
- they help control capillary permeability
- they are a subtype of CNS neuroglia
What do ependymal (neural epithelia) do? Where are they located? What are they a subtype of?
- they line brain ventricles and central canal of the spinal cord
- they secrete cerebrospinal fluid (CSF) and circulate it by cilia
- they are a subtype of CNS neuroglia
What are the 2 subtypes of PNS neuroglia?
- shwann cells
- satellite cells
Where are shwann cells do? What are they a subtype of?
- they form myelin around axons in PNS
- they are a subtype of PNS neuroglia
Where are satellite cells located? What are they a subtype of?
- they surround neuron cell bodies in ganglia for protection and support?
- they are a subtype of PNS neuroglia
What is structural/anatomical neuron classification based on?
based on # of cell processes off of cell body
Describe unipolar neurons
- has 1 process that divides into two: central and peripheral
- peripheral end has dendrites (sensory receptors for pain, touch, etc) remainder is axon
- always sensory
Describe bipolar neurons
- has 2 processes: 1 axon, 1 process with dendrites
- sensory: retina, nose (olfaction)
Describe multipolar neurons
- has 3 or more: 1 axon, many dendrites
- all interneurons and motor neurons
What are the functional types of neuron classification? What is it based on?
based on direction of impulse conduction
a) sensory/afferent
b) interneurons
c) efferent/motor
Describe sensory/afferent neurons
- mostly unipolar
- from sensory receptors to CNS
Describe interneurons
- within CNS (between sensory and motor)
- 99% of neurons (mostly multipolar)
Describe efferent/motor neurons
- CNS to effectors (all multipolar)
What are the 3 neuron junctions?
1) neuronal junction
2) neuromuscular junction
3) neuroglandular junction
Describe neuronal junctions
- neuron to neuron
- can be chemical (use neurotransmitters) or electrical (ions)
Describe neuromuscular junctions
- motor neuron to skeletal muscle
Describe neuroglandular junctions
- motor neuron to gland
What are they 4 most common chemical neuron synapses?
1) presynaptic neuron
2) axon terminal
3) synaptic cleft
4) postsynaptic neuron
What are presynaptic neurons?
- a type of chemical neuron synapses
- they bring impulse
What are axon terminals?
- a type of chemical neuron synapses
- have synaptic end bulbs: inside the bulbs (presynaptic membrane) are synaptic vesicles containing neurotransmitters
What are synaptic clefts?
- a type of chemical neuron synapses
- space between neurons
