1. The Central Nervous System PART 5
SPINAL CORD

2. CNS

3. Meninges of the Spinal Cord – same as the brain
Dura Mater (HARD MOTHER) - outer layer, strong white fibrous tissue.
Arachnoid membrane (SPIDER WEB) - middle layer, cobweb like layer.
Pia Mater (SOFT MOTHER)-inner layer, adheres to the brain, translucent.

4. The Spinal Cord
Located within the vertebral column along with the meninges, CSF, adipose tissue and blood vessels

5. The Spinal Cord
-Spinal Cord continues from the medulla oblongata and tapers off at L2 vertebrae (belly button)
-After L2, spinal cord continues as the strands of nerves called the filum terminate and cauda equina.

6. The Spinal Cord: Anatomy
2. Surrounds gray matter, contains tracts to and from the brain.
1. Shaped like H, where reflexes are processed
3. Filled with CSF

7. Quick Check Name 4 things found in the vertebral column.
At what vertebrae does the spinal cord taper off.
What are the group of nerves called that come off of the spinal cord after it tapers off?
The center of the spinal cord is made of gray matter and shaped like a what?

8. The Spinal Cord: Anatomy
Ascending Tracts
Conduct sensory impulses up to the brain
Descending tracts
Conduct motor impulses down from the brain

9. The Spinal Nerve: Anatomy
Dorsal nerve root
Carry sensory info to the spinal cord, (afferent pathways)
Cell bodies form the dorsal root ganglion before entering the spinal cord.
Thicker
Ventral nerve root
Carries motor info
out of spinal cord,
(efferent pathways)
-usually thinner
Spinal Nerve
Dorsal and Ventral root
Join together to form this
Single nerve

10. The Spinal Cord 4. Motor Response (Efferent) 1. Sensory Cell Bodies
3. Interneuron (Tract)
2. Sensory (Afferent)

11. Spinal Cord Injuries
Paralysis
Herniated Disk

12. Quick Check
What information does the dorsal root of the spinal nerve carry?
What information does the ventral root of the spinal nerve carry?
Which root pathway has a ganglion or group of cell bodies?

13. Reflex—CNS reflexes It may or may not be conscious.
Reflex is a predictable response to a stimulus.
It may or may not be conscious.
Sensory receptor
Sensory neuron
Interneuron(association) neuron
Motor neuron
Effector(muscle or gland)

14. Reflex Arc

15. Types of Reflexes 1. Cranial – reflex center located in brain
Ex: corneal reflex - eye blink
2. Somatic – spinal reflex involving skeletal muscles
Ex: patellar reflex – knee jerk
3. Autonomic – spinal reflex involving smooth or cardiac muscles
Ex: heart rate, breathing rate, glands

16. Peripheral Nervous System PART 6
Cranial and spinal nerves

17. PNS Somatic NS Autonomic NS Sympathetic NS Norepinephrine Epinephrine
Voluntary control
Sympathetic NS
Parasymathetic NS
Norepinephrine
Epinephrine
Acetylcholine
Prevents
over-stimulation
of involuntary action
Normal stimulation
of involuntary action
“Fight or flight”
“Rest and repair”

18. Nerves Cranial - come directly off of brain.
12 pairs of nerves that mostly serve the head and neck
Numbered in order, front to back
Most are mixed nerves, but three are sensory only
Spinal – come directly off of spinal cord

19. Cranial Nerves Figure 7.21 Slide 7.59
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

20. Spinal Nerve Structure

21. Sympathetic Nervous System
Neurotransmitters
Norepinephrine-stimulates normal functioning of the smooth and cardiac muscles
Epinephrine-causes “fight or flight response”
Increased heart rate and strength of contraction
Dilation of blood vessels in muscles
Constriction of blood vessels in digestive system
Dilated airways and increased respiration rate
Increased conversion of glycogen to glucose

22. Parasympathetic Nervous System
Neurotransmitter
Acetylcholine- reverses the effects of norepinephrine to maintain homeostasis
Slows the heart rate
Increase rate of peristalsis
Stimulates digestive and salivary glands

23. Reflex Arc—PNS reflexes
Reflex can be either muscular or glandular.
It is a predictable response to a particular stimulus.
Sensory receptor
Sensory neuron
Interneuron(association) neuron
Motor neuron
Affector(muscle or gland)

24. Reflex Arc

25. Types of Reflexes 1. Stretch – responds to increase load
Ex: knee reflex (patellar tendon)
2. Cutaneous – responds to touch
Ex: skin
3. Cranial – involves cranial nerves directly from brain.
Ex: eye blink