Lecture 1 - General Overview Flashcards
What are the two neuroanatomical divisions?
Central Nervous System (CNS) and Peripheral Nervous System (PNS)
Where is the CNS located?
Along central axis of the body
What comprises the CNS?
Brain & Spinal Cord
What are the two types of neural tissue in the CNS known as?
Grey matter & White matter
In the CNS, grey matter can refer to:
Neuron cell bodies, nuclei
In the CNS, white matter can refer to:
Myelinated axons, tracts, fasciculus, commissures
What structures are found in the brain portion of the CNS?
Cerebrum, cerebellum, brainstem
Where does the spinal cord end? What is the structure inferior to its ending called?
At approx. the lumbar vertebrae of the vertebral column; cauda equina
Everything that is NOT the CNS is the?
The PNS!
What two groups of nerves are found in the PNS? How many pairs of each are there?
31 pairs of spinal nerves
12 pairs of cranial nerves
Spinal nerves enter & exit where?
The spinal cord
MOST cranial nerves enter and exit where? Which cranial nerves are the exception?
Brainstem; olfactory & optic
PNS Efferent nerves send ________ to the periphery for _____ and ______
motor innervation; muscle control & gland secretion
PNS Afferent nerves bring _____ to the ______
Sensory info; CNS
What two types of neural tissue are found in the PNS?
Ganglia and nerves
Ganglia are groups of what?
Cell bodies
Nerves are bundles of what?
Axons
How do neurons in the CNS vs PNS respond to injury?
CNS - very limited regeneration; restricts recovery from brain injuries
PNS - neurons here can regenerate! (e.g. cutting your finger off, it can be stuck back on). Spinal nerves & cranial nerves can regenerate
A neuron in the CNS may degenerate back of a lack of _______ (___) or lack of ________ (____)
Sender (presynaptic), receiver (postsynaptic)
Axon sprouts are guided back together after severage through tubes made by ______ cells
Schwann
What divisions are found within the motor system of the somatic nervous system?
pyramidal & extrapyramidal
The pyramidal system is concerned with _____, where the extrapyramidal system is concerned with ______
Voluntary motor movement, subconscious motor control
Where are the origins of the pyramidal and extrapyramidal systems?
Pyramidal - cerebral cortex
Extrapyramidal - primarily brainstem
What two tracts are located in the pyramidal system? What are their responsibilities and where do they synapse?
Corticospinal tract - movement of limbs/trunk, synapses in SC & on lower motor neurons
Corticobulbar tract - movement of face, head & neck, synapses with cranial nerves
Damage to the lateral corticospinal tract results in what? These effects occur to muscles _____ to the level of injury
- ipsilateral paralysis (inability to move)
- paresis (decreased motor strength)
- hypertonia (increased tone)
…
Caudal to the level of injury
What are the main responsibilities of the extrapyramidal system?
Control of:
- involuntary movements for tone/balance
- reflexes
- movements that have become automatic
Facilitates:
- voluntary movements
Inhibition of:
- involuntary movements
What are the responsibilities of the sensory system within the somatic nervous system?
Collecting afferent signals from:
- skin, joints, and skeletal muscles
- the senses of: taste, smell, hearing, balance
Relays info about:
- limb position
- touch
- pressure at the body surface
The autonomic nervous system is responsible for only involuntary/voluntary control
Involuntary
What’s the difference between the sympathetic and parasympathetic system?
Sympathetic - increases heart reate, slows digestion (fright, flight, or fight)
Parasympathetic - restoring and maintaining homeostasis (rest-and-digest)
Where are the cell bodies for the sympathetic and parasympathetic systems?
Symp - thoracic and lumbar regions of SC (legs and lungs!)
Parasymp - brainstem & sacral regions of spinal cord (dream & stream!)
What are the 5 major divisions of the brain (from top to bottom)
Telencephalon
Diencephalon
Mesencephalon
Metencephalon
Myelencephalon
What structures comprise each of the 5 divisions of the brain
Telencephalon - cerebral hemispheres, basal ganglia, parts of limbic system
Diencephalon - thalamus, hypothalamus, subthalamus
Mesencephalon - midbrain
Metencephalon - pons, cerebellum
Myelencephalon - medulla oblongata
What is the soma of a neuron?
The central body, what contains the nucleus
What are dendrites
Tree like structures that project from the soma, ‘input structures’
What is an axon
A transmission channel
Typically one per cell
What is a myelinated axon? What disease causes the breakdown of myelin?
Provides insulation and faster speed of transmission
Multiple sclerosis - breakdown of myelin
Where do we find unmyelinated axons?
Very short axons do not always need myelin to be fast
e.g. Touch, heat, pain; hot surface touch reflex
How long are axons?
Axons can be short; <100 microns (micron is 1/1000 of a millimeter) to longer than a meter (e.g. sciatic nerve)
What are terminal buttons?
Output zones for the axon
What are projection neurons?
Long axons - can be efferent or afferent
What are interneurons?
Function locally
More than 99% of all neurons in the body
Connect sensory with motor neurons
Interconnect neurons in the brain
Upper motor neurons have their cell body and synapse entirely in the _______
CNS
Lower motor neurons have their cell body in the ______ and synapse on the _____, making it part of the _
CNS, muscle, PNS
The action potential travels along what?
The axon
At the _________: neurotransmitters are released into the _______ cleft
Presynaptic terminal, synaptic
Neurotransmitters bind to the receptors in the __________ membrane. This is known as a __________ potential, and can be __________ or ________
Post-synaptic, postsynaptic, excitatory or inhibitory
One neuron may make contact with up to how many synapses?
10,000!
The most abundant cell type in the brain are?
Glial cells
Glial cells are also known as?
Support cells
What types of glial cells are found in the CNS? What are their functions?
Astrocytes (nutrients and oxygen, recycling neurotransmitters, blood brain barrier, long-term memory and formation of synapses)
Oligodendrocytes (myelin sheet around axons)
Microglia (immune defense system in the brain)
What type of glial cell is found in the PNS? What is its function?
Schwann cells, responsible for the myelin of peripheral nerves
