1. Warm-Up Name the 2 main organs of the nervous system.
Draw and label the parts of a neuron.

2. Warm-Up
Label the parts of the neuron below. A B E F C G D

3. Warm-Up
One neuron transmits a nerve impulse at 40 m/s. Another conducts at the rate of 1 m/s. Which neuron has a myelinated axon?
List the following in order:
K+ channels open and K+ floods out of cell
Membrane is polarized (resting potential)
Neurotransmitters are released from vesicles into synaptic cleft
Na+ channels open and Na+ floods into cell
Stimulus triggers membrane depolarization
What restores the resting potential of a neuron?

4. The Nervous System

5. Nervous System
Master controlling and communicating system

6. Basic Functions Sensory input – gather information
Integration – process and interpret sensory input
Motor output – response by muscles and glands

7. Organization Central Nervous System (CNS) Brain & spinal cord
Integrative and control centers
Peripheral Nervous System (PNS)
Nerves (spinal nerves, cranial nerves)
Communication lines between CNS and rest of body
Two Divisions:
Sensory (afferent) Division: Sensory receptors  CNS
Motor (efferent) Division: CNS  effectors (muscles & glands)

8. Motor Division
Somatic nervous system (voluntary) – control skeletal muscles
Autonomic nervous system (ANS) (involuntary) – regulate smooth muscles, cardiac, glands
Subdivisions: sympathetic & parasympathetic

10. Nervous Tissue Neurons (nerve cells) - transmit message Anatomy:
Cell body – contains nucleus; metabolic center
Dendrite – fiber that conveys messages toward cell body
Axon – conduct nerve impulses away from the cell body
Axon terminals – end of axon; contain neurotransmitters & release them
Synaptic cleft/synapse – gap between neurons

12. Myelin: whitish, fatty material that covers nerve fibers to speed up nerve impulses
Schwann cells: surround axons and form myelin sheath
Myelin sheath: tight coil of wrapped membranes
Nodes of Ranvier: gaps between Schwann cells

13. rotates around the axon, wrapping its plasma membrane loosely around
Schwann cell
plasma membrane
Schwann cell
cytoplasm
A Schwann cell
envelopes an axon. 1
Axon
Schwann cell
nucleus
The Schwann cell then
rotates around the axon,
wrapping its plasma
membrane loosely around
it in successive layers. 2
Neurilemma
The Schwann cell
cytoplasm is forced from
between the membranes.
The tight membrane
wrappings surrounding
the axon form the myelin
sheath. 3
Myelin sheath
(a) Myelination of a nerve fiber (axon)
Figure 11.5a

14. Nervous Tissue Supporting cells Neuroglia CNS:
astrocytes create the blood-brain barrier between capillaries and neurons
microglia immune/defense
ependymal cells line brain and spinal cord cavities and produce cerebrospinal fluid
Oligodendrocytes wrap axons; produces myelin sheaths (covering)
PNS:
Schwann cells wrap axons; produces myelin sheaths (covering)
satellite cells give support to neurons and regulate chemical environment

16. Classification of Neurons

17. Functional Classification: direction nerve impulse is traveling
Sensory neurons
Motor neurons
Interneurons
carry impulses from sensory receptors to CNS
carry impulses from CNS to muscles & glands
connect sensory & motor neurons
Vision, hearing, equilibrium, taste, smell, pain, pressure, heat

18. Functional Classification: direction nerve impulse is traveling
Sensory Neurons
afferent
most are unipolar
some are bipolar
Interneurons
multipolar
in CNS
Motor Neurons
efferent
carry impulses to effectors, muscle or gland

20. Structural Classification: # processes extending from cell body
Multipolar
Bipolar
Unipolar
1 axon, several dendrites
1 axon, 1 dendrite
1 process
Most common (99%)
Rare
Short with 2 branches (sensory, CNS)
Eg. Motor neurons, interneurons
Eg. retina, nose, ear
Eg. PNS ganglia

21. Structural Classification: # processes extending from cell body
Multipolar neurons
Bipolar
Unipolar

23. Ganglia: collections of cell bodies
Bundles of nerve fibers = tracts (CNS) or nerves (PNS)
White matter: dense collections of myelinated fibers
Gray matter: unmyelinated fibers & cell bodies

24. Neurotransmitters Neurotransmitter Action Affected by: Acetylcholine
muscle contraction
botulism, curare (paralytic), nicotine
Dopamine
“feeling good”
cocaine, amphetamines
Serotonin
sleep, appetite, nausea, mood, migraines
Prozac, LSD, ecstasy
Endorphins
inhibit pain
morphine, heroin, methadone
GABA
main inhibitory NT
alcohol, Valium, barbiturates

25. Protection of CNS Meninges: connective tissue covering CNS structures
Dura mater (leathery outer), arachnoid mater (web-like middle), pia mater (surface of brain)
Cerebrospinal fluid (CSF): watery cushion to protect NS from trauma

27. Blood-Brain Barrier: endothelial cells in capillaries prevent substances from crossing into brain
NO:
YES:
Urea
Toxins
Proteins
White blood cells
Bacteria
Most drugs
Water
Glucose
Amino acids
Gases
Fat-soluble substances
Some drugs: anesthetics, alcohol, nicotine

28. Skin of scalp Periosteum Bone of skull Dura Periosteal mater Meningeal
Superior
sagittal sinus
Arachnoid mater
Pia mater
Subdural
space
Arachnoid villus
Blood vessel
Subarachnoid
space
Falx cerebri
(in longitudinal
fissure only)
Figure 12.24

29. Right lateral ventricle (deep to cut)
Superior
sagittal sinus 4
Choroid
plexus
Arachnoid villus
Interventricular
foramen
Subarachnoid space
Arachnoid mater
Meningeal dura mater
Periosteal dura mater 1
Right lateral ventricle
(deep to cut)
Choroid plexus
of fourth ventricle 3
Third ventricle
CSF is produced by the
choroid plexus of each
ventricle. 1
Cerebral aqueduct
Lateral aperture
Fourth ventricle
CSF flows through the
ventricles and into the
subarachnoid space via the
median and lateral apertures.
Some CSF flows through the
central canal of the spinal cord. 2
Median aperture 2
Central canal
of spinal cord
CSF flows through the
subarachnoid space. 3
(a) CSF circulation
CSF is absorbed into the dural venous
sinuses via the arachnoid villi. 4
Figure 12.26a

30. Label the parts of the neuron below using the following terms: axon terminal, cell body, dendrite, myelin sheath, node of Ranvier, nucleus of the neuron, Schwann cell nucleus. A B E F C G D