The Central The Central Nervous System Nervous System

PART 5PART 5SPINAL CORD

CNSCNS

Meninges of the Spinal Meninges of the Spinal Cord – same as the brainCord – same as the brain

Dura Mater Dura Mater (HARD MOTHER) (HARD MOTHER) - outer layer, strong white - outer layer, strong white fibrous tissue.fibrous tissue.

Arachnoid membrane Arachnoid membrane (SPIDER WEB) - middle layer, (SPIDER WEB) - middle layer, cobweb like layer.cobweb like layer.

Pia Mater Pia Mater (SOFT MOTHER)-(SOFT MOTHER)-inner layer, adheres to the inner layer, adheres to the brain, translucent. brain, translucent.

The Spinal CordThe Spinal Cord Located within the vertebral column Located within the vertebral column

along with the meninges, CSF, adipose along with the meninges, CSF, adipose tissue and blood vesselstissue and blood vessels

The Spinal CordThe 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.

The Spinal Cord: The Spinal Cord: AnatomyAnatomy

1. Shaped like H, where reflexes are processed

2. Surrounds gray matter, contains tracts to and from the brain.

3. Filled with CSF

Quick CheckQuick Check1.1. Name 4 things found in the vertebral Name 4 things found in the vertebral

column.column.

2.2. At what vertebrae does the spinal cord At what vertebrae does the spinal cord taper off.taper off.

3.3. What are the group of nerves called What are the group of nerves called that come off of the spinal cord after it that come off of the spinal cord after it tapers off?tapers off?

4.4. The center of the spinal cord is made The center of the spinal cord is made of gray matter and shaped like a what?of gray matter and shaped like a what?

The Spinal Cord: The Spinal Cord: AnatomyAnatomy

Ascending Ascending TractsTracts Conduct Conduct

sensory sensory impulses impulses up to up to the brainthe brain

Descending Descending tractstracts Conduct Conduct motor motor

impulsesimpulses down down from the brainfrom the brain

The Spinal Nerve: The Spinal Nerve: AnatomyAnatomy Dorsal nerve rootDorsal nerve root

Carry Carry sensory info sensory info to the spinal cord, (to the spinal cord, (afferent afferent pathwayspathways))

Cell bodies form the dorsal root ganglion before Cell bodies form the dorsal root ganglion before entering the spinal cord.entering the spinal cord.

ThickerThicker Ventral nerve rootVentral nerve root

Carries Carries motor infomotor infoout of spinal cord,out of spinal cord,((efferent pathwaysefferent pathways))

-usually thinner-usually thinner Spinal NerveSpinal Nerve

Dorsal and Ventral root Dorsal and Ventral root Join together to form this Join together to form this Single nerveSingle nerve

The Spinal CordThe Spinal Cord

2. Sensory (Afferent)

1. Sensory Cell Bodies

4. Motor Response (Efferent)

3. Interneuron (Tract)

Spinal Cord InjuriesSpinal Cord InjuriesParalysisHerniated Disk

Quick CheckQuick Check

5.5. What information does the dorsal What information does the dorsal root of the spinal nerve carry?root of the spinal nerve carry?

6.6. What information does the ventral What information does the ventral root of the spinal nerve carry?root of the spinal nerve carry?

7.7. Which root pathway has a ganglion Which root pathway has a ganglion or group of cell bodies?or group of cell bodies?

Reflex—CNS reflexesReflex—CNS reflexes Reflex is a predictable response to a stimulus.Reflex is a predictable response to a stimulus.

It may or may not be conscious.It may or may not be conscious.

Sensory receptor

Sensory neuron

Effector(muscle or gland)

Motor neuron

Interneuron(association) neuron

Reflex ArcReflex Arc

Types of ReflexesTypes of Reflexes

11. . CranialCranial – reflex center located in brain – reflex center located in brain

Ex: corneal reflex - eye blinkEx: corneal reflex - eye blink

2. 2. SomaticSomatic – spinal reflex involving skeletal muscles

Ex: patellar reflex – knee jerk

3. 3. Autonomic – spinal reflex involving – spinal reflex involving smooth or cardiac musclessmooth or cardiac muscles

Ex: heart rate, breathing rate, Ex: heart rate, breathing rate, glands glands

Peripheral Peripheral Nervous System Nervous System

PART 6PART 6Cranial and spinal nerves

PNS

Somatic NS

Autonomic NS

Parasymathetic NSSympathetic NS

“Fight or flight” “Rest and repair”

Voluntary control

Normal stimulation

of involuntary action

Prevents

over-stimulation

of involuntary action

Norepinephrine EpinephrineAcetylcholine

NervesNerves

CranialCranial - come directly off of brain. - come directly off of brain. 12 pairs of nerves that mostly serve the head 12 pairs of nerves that mostly serve the head

and neckand neck

Numbered in order, front to backNumbered in order, front to back

Most are mixed nerves, but three are Most are mixed nerves, but three are sensory onlysensory only

Spinal Spinal – come directly off of spinal – come directly off of spinal cordcord

Slide 7.59Slide 7.59Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Figure 7.21

Cranial NervesCranial Nerves

Spinal Nerve StructureSpinal Nerve Structure

Sympathetic Nervous Sympathetic Nervous SystemSystem

NeurotransmittersNeurotransmitters

Norepinephrine-stimulates normal functioning Norepinephrine-stimulates normal functioning of the smooth and cardiac musclesof the smooth and cardiac muscles

Epinephrine-causes “fight or flight response”Epinephrine-causes “fight or flight response” Increased heart rate and strength of Increased heart rate and strength of

contractioncontraction Dilation of blood vessels in musclesDilation of blood vessels in muscles Constriction of blood vessels in digestive Constriction of blood vessels in digestive

systemsystem Dilated airways and increased respiration Dilated airways and increased respiration

raterate Increased conversion of glycogen to glucoseIncreased conversion of glycogen to glucose

Parasympathetic Nervous Parasympathetic Nervous SystemSystem

NeurotransmitterNeurotransmitter Acetylcholine- reverses the effects of Acetylcholine- reverses the effects of

norepinephrine to maintain norepinephrine to maintain homeostasishomeostasis Slows the heart rateSlows the heart rate Increase rate of peristalsis Increase rate of peristalsis Stimulates digestive and salivary glandsStimulates digestive and salivary glands

Reflex Arc—PNS reflexesReflex Arc—PNS reflexes Reflex can be either muscular or Reflex can be either muscular or

glandular.glandular. It is a predictable response to a particular It is a predictable response to a particular

stimulus.stimulus.Sensory receptor

Sensory neuron

Affector(muscle or gland)

Motor neuron

Interneuron(association) neuron

Reflex ArcReflex Arc

Types of ReflexesTypes of Reflexes

1. 1. StretchStretch – responds to increase load – responds to increase load

Ex: knee reflex (patellar Ex: knee reflex (patellar tendon)tendon)

2. 2. CutaneousCutaneous – responds to touch – responds to touch

Ex: skinEx: skin

3. 3. CranialCranial – involves cranial nerves – involves cranial nerves directly from brain.directly from brain.

Ex: eye blinkEx: eye blink