1. Nervous System

2. B. Supporting cells of the CNS
Oligodendrocytes
Astrocytes: protoplasmic
fibrous
Microglia
Ependymal cells

3. ① oligodendrocytes
One oligodendrocyte may myelinate one axon or several nearby axons

4. ② Astrocytes ＋
Protoplasmic astrocyte
Fibrous astrocyte

5. ③ Ependymal cells
Line the brain ventricles and central canal of the spinal cord
Some are ciliated to facilitate the movement of cerebrospinal fluid

6. ④ Microglia Derived from bone marrow, phagocyte in nerve tissue
Involved with inflammation and repair in the CNS

7. Summary 2
Supporting cells in the PNS
Myelin sheath
neuroglia

8. I. The peripheral nervous system
Nerve fibers
Ganglia
Nerve ending

9. 1. Nerve fibers
A peripheral nerve is a bundle of nerve fibers held together by connective tissue

10. Unmyelinated nerve fiber

11. 2. Ganglia
Ovoid structures containing neuronal cell bodies and glial cells supported by connective tissue
The direction of the nerve impulse determines whether sensory or autonomic ganglia.

12. Sensory ganglia: receive afferent impulses that go to the CNS
Cranial ganglia: cranial nerves
Spinal ganglia: dorsal root of spinal nerves
Autonomic ganglia:
Sympathetic: paravertebrate, preveterbrate
Parasympathetic: close to organs or in organs

13. 3. Nerve ending Sensory nerve ending Motor nerve ending
Free: pain, temperature
encapsulate
Motor nerve ending
Motor end plate
Visceral motor
Tactile corpuscle: sense of touch
Lamellar corpuscle: pressure, vibration
Muscle spindle: limbs position

14. Tactile corpuscle
Lamellar corpuscle
Muscle spindle
Motor end plate

15. Autonomic nervous system
The ANS consists of motor neurons that:
Innervate smooth and cardiac muscle and glands (most of the effectors are viscera)

17. Three major differences in the ANS and SNS
Effectors
Efferent pathways
Target organ responses

18. Effectors The effectors of the SNS are skeletal muscles
The effectors of the ANS are cardiac muscle, smooth muscle, and glands

19. Efferent Pathways
Myelinated axons of the somatic motor neurons extend from the CNS to the effector (lacks ganglia)
Pathways in the ANS are a two-neuron chain
The preganglionic (first) neuron has a lightly myelinated axon. The ganglionic (second) unmyelinated neuron extends to an effector organ via the postganglionic axon

20. Neurotransmitter Effects
All somatic motor neurons release Acetylcholine at their synapses, Ach always has an excitatory effect
In the ANS:
Preganglionic fibers release ACh
Postganglionic fibers release norepinephrine (most s.) or ACh (p.) and the effect is either stimulatory or inhibitory

22. The nuclei of the Sym. are located in the thoracic and lumbar segments of the spinal cord.
The 2nd neuron is located in sensory ganglia.
The nuclei of the Para. are located in the medulla and midbrain and in the sacral portion of the spinal cord.
The 2nd neuron is in ganglia located near or within the effector organs

23. II. The central nervous system
Cerebrum
Cerebellum
Spinal cord
CNS has almost no connective tissue,
A relatively soft gel-like tissue.

24. White matter Gray matter
Myelinated nervous fibers and oligodendrocytes
Gray matter
Neuronal cell bodies
dendrites
Initial segment
Glial cells

25. 1. Cerebrum
The gray matter forms cortex, the white matter forms medulla.
Cerebral cortex has six layers of cells

26. Sensory inputs first activate neurons in layer 4, which propagate the excitement up to layer 2,3, and down to layer 5,6

27. 2. Cerebellar cortex has 3 layers
Out molecular layer
Purkinje cells layer
Inner granular layer
Purkinje cells are the efferent neurons
Mossy and climbing fibers are afferent fibers

29. 3. Spinal cord
DH: sensory fibers form dorsal root
VH: motor neurons

31. 4. Connective tissue of the CNS
Meninges
Connective tissue encase the skull and the vertebral column
Dura mater
Arachnoid
Pia mater
The region between the arachnoid and pia mater is filled with CSF

32. 5. Blood-brain barrier (BBB)
Prevents the passage of some substances, such as chemical and bacterial toxin matter, from the blood to nerve tissue

33. Response of neurons to injury

34. Summary The PNS Nerve fibers, ganglia, nerve ending
Autonomic nerve system
The CNS
Spinal cord
Cerebrum
Cerebellum
Meninges

35. Questions
List differences between the Central and Peripheral nervous systems.
List difference between the somatic and autonomic nervous systems