Lecture 1: Intro to Neuroanatomy Flashcards
What are the two main divisions of the Nervous System?
CNS and PNS
What are the divisions of the CNS?
•Brain
•Spinal cord
What are the divisions of the brain?
•Cerebellum
•Brainstem
•Cerebellum
What are the functions of the CNS?
•Integrates processes and coordinates sensory data and motor commands
•Seat of higher functions
What are the parts of the seat of higher functions?
•Intelligence
•Memory
•Learning
•Emotions
What is the CNS protected by?
Bone
What is the PNS surrounded by?
Soft tissue
What are the two divisions of the PNS?
•Somatic
•Autonomic
What are the two divisions of the the somatic PNS?
•Motor
•Sensory
What are the two division of the autonomic PNS?
•Motor
•Sensory
What are the two divisions of the Motor component of the autonomic nervous system?
•Sympathetic
•Parasympathetic
What does Somatic mean?
Body wall
What kind of control is the autonomic nervous system under?
Not under voluntary control
What are some examples of autonomic control?
Nerve supply to the viscera, lungs, gut, sweat glands
What are some examples of the somatic nervous system?
The feeling of the skin, or ache when sick, muscle tears, broken bones
What is an example of the sensory portion of the autonomic nervous system?
Stomach ache when eating a big meal
What are Nerve Fibers?
Axons of neurons in the PNS
What is a Nerve?
A collection of axons in the PNS
What are Ganglia?
A collection of cell bodies in the PNS
What are the functions of the PNS?
•Carries sensory information from receptors to CNS
•Carries motor commands from the CNS to peripheral tissues and systems
What does the Afferent division of the PNS do?
Carries sensory information from receptors to CNS
What does the Efferent division of the PNS do?
Carries motor commands from the CNS to peripheral tissues and systems
What does Somatic Sensory include?
•Skin
•Nervous tissue under the skin
•Sensory fibres in muscle and bone
What does Autonomic Sensory include?
Only sensations when something is wrong
•Pain
•Ischemia
What kind of matter is on the outer portion of the brain?
Grey matter
What kind of matter is the inner portion of the brain made of?
White matter
Why is the inner part of the brain made of white matter?
Because these are the axons of the neurons
What does grey matter indicate?
That neuronal cell bodies are present
Where are all the neuronal cell bodies in the brain located?
The outer part
What does white matter present indicate?
Axons
What is a Nucleus?
A collection of cell bodies in the CNS
What is the difference between a Nucleus and a Ganglia?
•A collection of cell bodies in the CNS is a Nucleus
•A collection of cell bodies in the PNS is a Ganglia
What is a Tract?
A bundle of axons in the CNS
What is the difference between a Tract and a Nerve?
•A Tract is a collection of axons in the CNS
•A Nerve is a collection of axons in the PNS
How many layers are in the outer grey matter of the brain?
6 layers
Who was the father of neuroscience?
Ramon y Cajal
What do all neurons have?
•Cell body
•Dendrite (cytoplasmic processes)
•Axon Hillock
What do dendrites do?
Receives signals from other neurons
What does the axon hillock do?
Elicits the action potential
Which neurons are always myelinated?
Motor neurons
Why does the sensory neuron look different than the cortical and motor neurons?
•Doesn’t have a dendrite
•Has two axons
Where is the cell body for all sensory neurons located?
In the PNS in Ganglia
What do sensory neurons lack?
Dendrites
Which neurons have dendrites?
•Cortical Neurons
•Motor neurons
Where are Purkinje neurons found?
In the cerebellum
What is the functional unit in the nervous system?
The neurons
What is the function of the Neuron?
Transmit information to other cells
What is the Electrical signalling of a neuron?
Neurotransmission via action potential
What is the chemical signalling of a neuron?
Synthesis, transport and release of neurotransmitters at the synaptic terminal
What is a Synapse?
A point of contact of an axon terminal with another nerve or target cell
What is the function of a Synapse?
Transmits nerve impulses via chemical neurotransmitters
In what direction do nerve impulses flow?
Unidirectional
What do motor neurons synapse on?
Muscle and glands
Where are the cell bodies of somatic motor neurons found?
In the spinal cord
What neurotransmitter do somatic motor neurons release?
Acetylcholine
What are the two classes of cells in the nervous system?
•Neurons
•Neuroglial cells
What do Neuroglial cells do?
•Support and protect neurons
•Form the connective tissue of the nervous system
•Signal to each other and other neurons
What are the Glial cells found in the PNS?
•Schwann cells (myelin)
•Satellite cells
What are the Glial cells found in the CNS?
•Oligodendrocytes (myelin)
•Astrocytes
•Microglia
•Ependymal cells
Which glial cells form the Myelin in the PNS and CNS?
•PNS - Schwann cells
•CNS - Oligodendrocytes
What does Myelination help with?
Rapid transmission of nerve impulses
What is the Myelin sheath?
Plasma membrane with specialization to it
What do Satellite cells do?
•Surround sensory neurons in dorsal root ganglion (DRG)
•Regulates O2, CO2 and neurotransmitters
What do satellite cells surround?
Sensory neurons in the DRG
What do Schwann cells do?
•Surround all sensory neurons
•Myelinate peripheral axons
•Provides support for unmyelinated axons (remark bundles)
•Participate in regeneration
What do Schwann cells surround?
All sensory neurons
Where are the motor neuron cells bodies always located?
In the ventral horn of the spinal cord
Where are somatic motor neuron cell bodies always found?
In the ventral horn of the spinal cord
What are motor neurons myelinated by?
They are first myelinated by oligodendrocytes in the spinal cord then by Schwann cells in the PNS
What do Oligodendrocytes do?
•Myelinate CNS axons
•Provide structural framework
What do Astrocytes do?
•Maintain BBB
•Regulate ion, nutrient, dissolved gas concentration
•Absorb and recycle neurotransmitters
•Forms glial scar after injury
What do Microglia do?
•Remove cell debris, wastes and pathogen by phagocytosis
What myelinates CNS axons?
Oligodendrocytes
What happens if you lose one oligodendrocyte?
Because they myelinate so many neurons in the CNS there will be more effects than losing a Schwann cell
What cells maintain the BBB?
Astrocytes
What cells absorb and recycle neurotransmitters?
Astrocytes
What cells form glial scars after injury?
Astrocytes
What is the downside of Astrocytes?
They remain after injury and form scarring and prevent neurons from trying to regrow
What are the Macrophages of the brain?
Microglia
What do Ependymal cells do?
•Line ventricles (brain) and the central canal (spinal cord)
•Help produce, circulate and monitor cerebrospinal fluid
Where are Sensory neuronal cell bodies located?
In ganglia in the PNS
What is white matter?
Aggregates of myelinated fibres
What is Grey matter?
Collections of neuronal cell bodies, dendrite and unmyelinated axons
Why does grey matter look grey?
Because it lacks myelin
What is the distribution of grey and white matter in the brain?
The grey is on the outside, and the white is on the inside
What is the distribution of grey and white matter in the Spinal Cord?
White on the outside and grey on the inside
How can you tell which is the dorsal and ventral side of a spinal cord?
The ventral portion will not have grey matter touch the outside but the dorsal will
Which part of the spinal cord are the motor neuronal cell bodies?
In the ventral part of the spinal cord
Which part of the spinal cord do sensory axons enter?
The dorsal part
What are the three layers of a nerve?
•Epineurium (outermost)
•Perineurium
•Endoneurium (innermost)
What is the outermost layer of a nerve?
The epineurium
What is the middle layer of a nerve?
Perineurium
What is the innermost layer of a nerve?
Endoneurium
What do large diameter sensory neurons sense?
•Touch, pressure
•Vibration
What do small diameter sensory neurons sense?
Pain and temperature
Which is faster large or small diameter axons and why?
Large are faster because they are heavily myelinated
What are Dorsal Root Ganglia?
The cell bodies of primary sensory neurons
What kind of neurons are in the Dorsal Root Ganglia?
Pseudounipolar neurons
What are the cell bodies in the Dorsal Root Ganglia surrounded by?
Satellite cells
