Download Lecture 2

The Nervous System
http://www.youtube.com/watch?v=Q4uh2r1djWw
An organ is composed of different tissues
Epithelial cells
Connective
tissue
Muscle tissue
The Nervous System
- General organization
- The basic units- the cells
- Neurophysiology
- Neural interactions
Brain, Spinal cord, Neuronal pathways, Special senses
The Human Nervous System
The Central
Nervous System
(CNS)
The Peripheral
Nervous System
(PNS)
The Nervous System
Monitors changes
Processes and interprets
Causes a response
Sensory
receptors
PNS
CNS
Central Nervous system
sensory
Peripheral Nervous system
Sensory (Afferent)
motor
Motor (Efferent)
Somatic (skin, skeletal
muscle and joints)
Visceral (internal
organs)
Somatic
Autonomic
Skeletal muscles
Smooth and cardiac
muscles; Glands
Neurons
“The Mysterious Butterflies of the Soul”
Santiago Ramón y Cajal
(1852-1934)
“As the entomologist chasing butterflies of bright
colors, my attention was seeking in the garden of
gray matter, those cells of delicate and elegant forms,
the mysterious butterflies of the soul, whose
fluttering wings would someday—who knows?—
enlighten the secret of mental life”
Neurons
“The Mysterious Butterflies of the Soul”
Santiago Ramón y Cajal
Nobel prize in
physiology and
medicine 1906
The neuron
Most of our wiring is insulated
Myelin sheath
Myelin sheath
• Whitish, fatty (protein-lipoid), segmented
sheath around most long (NOT ALL) axons
• It functions to:
- Protect the axon
- Electrically insulate fibers from one another
- Increase the speed of nerve impulse transmission
Myelin sheath
• Formed by Schwann cells in
the PNS
• A Schwann cell:
- Envelopes an axon in a trough
- Has concentric layers of
membrane that make up the
myelin sheath
Axons are bundled together to form fascicles
CNS: axon bundles form tracts
PNS: axon bundles form nerves
Neurons are not alone
The supporting neuroglia
Astrocytes
Microglia
The “immune
cells” of the CNS
- Support and brace neurons
- Control the chemical environment
Ependymal cells
- Circulating the CSF
Oligodendrocytes
- Insulators of the
thick neurons of
the CNS
Ependymal cells
- Ciliated epithelial cells
lining the central cavities of
the brain and spinal column
- Forming a permeable
barrier between the CSF
and nervous tissue
- Beating cilia helps
circulating the CSF
CSF
(cerebrospinal fluid)
-Beating cilia helps circulating the CSF
A
Banizs et al. Development (2005)
B
The supporting neuroglia
Astrocytes
Microglia
The “immune
cells” of the CNS
- Support and brace neurons
- Control the chemical environment
Ependymal cells
- Circulating the CSF
Oligodendrocytes
- Insulators of the
thick neurons of
the CNS
The neural cells of the CNS
The supporting neuroglia in the PNS
- Schwann cells
surround and insulate axons
(the “oligodendrocytes” of the PNS)
- Satellite cells
Support, insulate and nourish cell bodies
(“astrocytes” of the PNS)
Fundamentals of the nervous system
General Organization
- CNS and PNS
- PNS subgroups
The basic units- the cells
- Neurons
- Glial cells
Neurophysiology
- Resting, graded and action potentials
Neural interactions
Post-lecture assignment in Connect
- Use the slides and the textbook to review
the material
- The quiz can be answered only once
- Please note: the deadline is Aug 28, 11:00pm
- The quiz will be submitted automatically on
Aug 28, 11 pm