Peripheral Nervous Systems

(Spinal and Cranial nerves, Autonomic Nervous System)

Chapter 13

I. Characteristics of spinal cord

A. ______

B. ______

C. ______

D. ______

E. ______

F. ______

G. Gray Matter

a. Looks like an ______in cross section

b. Contains:

1. posterior (______) horns – axons of sensory neurons and association neurons

2. Anterior (______) horns - cell bodies of somatic motor neurons

c. Amount of gray matter reflects amount of ______innervated at that level

H. Nerve Roots

a. Dorsal nerve root – carries incoming messages (______)

b. Ventral nerve root – carries outgoing messages (______)

  1. Dorsal and ventral roots join to form ______“spinal nerves”
  2. area of skin innervated by each spinal nerve = “______”
  3. muscle group innervated by each spinal nerve = “______”

K. White Matter

a. “Nerve tracts” of myelinated and unmyelinated fibers running in 3 directions:

1. Up (______;______)

2. Down (______;______)

3. side to side

L. Pathology

a. ______– loss of motor function

b. ______– loss of sensation

c. ______– loss of lower limb function

d. ______– loss of all limb function

e. ______– brain disorder resulting in loss of function on one side

f. ______– loss of muscle tone due to damage of ventral horn or root

g. ______– damage to brain neurons; muscles are stimulated by spinal

nerves

h. ______– “gray matter; inflammation” – ______disease which destroys the ______of the spinal cord; virus is contracted through contaminated ______; Salk and Sabin ______prevent infection

II. Peripheral Nervous System

A. Cranial Nerves

a. ______pair; only ______of which extends down into the body

b. Usually named for what they ______

c. Given ______numerals in the order in which they are located

d. ______(structural)

e. “______”

I – Olfactory - ______

II – Optic - ______

III – Oculomotor - ______

IV – Trochlear – ______

V – Trigeminal – ______

VI – abducens – ______

VII – facial – ______

VIII – vestibulochochlear – ______

IX – Glossopharyngeal – ______

X – Vagus – ______

XI – Accessory – ______

XII – Hypoglossal – ______

f. Cranial nerves can be ______,______,

or ______(both)

g. ______

B. Spinal Nerves

a. 31 pairs; all are ______nerves:

b. ______cervical

c. ______thoracic

d. ______lumbar

e. ______coccygeal

C. Spinal nerves leave the spinal cord, ______and then converge again to form a

complicated network called a “______”

a. Allows muscles to receive its nerve supply from ______

b. Therefore a damaged nerve does not lead to complete motor or sensory loss in the limb region

served

c. There are several major plexi:

1. ______– neck; phrenic nerve (diaphragm) is here

2. ______– upper limbs; radial nerve is the largest

3. ______– abdominal wall and thigh; femoral nerve is largest

4. ______– thigh and lower leg; sciatic nerve (largest and

longest nerve in body)

III. Reflexes

A. Reflexes are rapid, predictable motor responses to stimuli;______, ______, and ______; 2 kinds:

a. ______– skeletal muscle

b. ______– glands and involuntary muscle

B. Reflex arc contains 5 elements:

a. ______

b. ______neuron

c. ______– association neurons of spinal cord

d. ______

e. ______(muscle or gland)

C. Examples of reflexes:

  1. ______(deep tendon) reflex – coordinates muscle control of paired muscles (bicep/tricep); prevents over stretching, muscle tone
  2. ______(ankle jerk) reflex
  3. ______vs. ______reflex

d. ______(abdominal) reflex – initiated by actual or perceived painful event; prick finger, hot stove, punch to abdomen, etc.

e. ______reflex – complex; helps to maintain balance

f. ______reflex – initiated by gentle touch; Babinski sign

  1. ______reflex – protective

IV. Autonomic Nervous System

*Autonomic Nervous System – Responsible for the stability of the body’s ______(blood flow, respiration rate, body temperature change, etc.)

  1. Overview – Difference between somatic and autonomic
  2. ______:

1. ______= skeletal muscle

2. ______= cardiac & smooth muscle, glands

  1. ______;

1. Somatic = cell bodies are in the ______, axons ______which go to the ______; neurons are thick and myelinated

  1. Autonomic = chain of __ neurons; 1st neuron (preganglionic) in ______; 2nd neuron (postganglionic) in ______; fibers are thing and lightly myelinated
  2. Neurotransmitter effects:

1. Somatic – acetylcholine (______); effects are always ______

2. Autonomic = norepinephrine (______) (usually found in parasympathetic) effects depend on the type of receptor receiving the transmitter; it can be ______

or ______.

  1. Sympathetic vs. Parasympathetic – Generally serve the same organs, but cause ______effects
  2. ______- speed things up; emergencies which cause the heart to speed up, blood to be shunted during exercises, bronchioles to dilate, nutrients are pulled from the liver, etc. “______’
  3. ______- works to conserve body energy; unwind; active when the body is at rest; called the “______” system
  4. Homeostasis is maintained through the ______- action of these two.
  5. Anatomy
  6. ______- preganglionic sympathetic neurons arise from the T1-L2 vertebrae

b.______- preganglionic parasympathetic neurons arise from the brainstem (cranium) and sacrum (sacral) regions of the spinal cord.

  1. Physiology – Neurotransmitter and Receptor Action
  2. ______and ______are the major neurotransmitters
  3. Ach is secreted by all ______of the sympathetic and parasympathetic fibers and all ______of the parasympathetic = ______fibers.
  4. NE is secreted by all postganglionic fibers of the ______-- = ______(named after hormone adrenaline which produces the same effects)
  5. Receptors

1. ______receptors – named form drugs that bind and behave like ACh

i. ______(named after nicotine) = ______

effects; example are receptors on adrenal glands.

ii. ______(named after muscarine, a mushroom poison) =

______or ______depending on

where in the body; Ex: Ach binding to heart muscle will slow it down; Ach binding to

stomach muscle, sweat glands, intestines will speed them up.

  1. ______receptors – organs that respond to NE have one or both types of receptors

i. ______- generally excitatory; Ex: blood vessel constriction

ii. ______- generally inhibitory, except in the heart; Ex: dilates blood vessels &

bronchiole tubes, relaxes intestine

  1. Knowing the locations of these receptors and subclasses is helpful in ______design and use; current technology is to develop drugs that target one type of ______without interfering with all receptors body wide; in other words design a drug that targets just the nicotinic receptors and not the muscarinic receptors. Ex: ______- drugs that bind to and block 1 receptors of the heart without interfering with the 2 receptors of other organs.
  2. Interactions – both systems do not exhibit dual control; usually, both are partially activated and antagonistic; exceptions are:

i. ______- vasomotor constriction; thermoregulation and responses to heat (skin dilates), rennin (enzyme from kidneys that causes an increase in blood pressure), body cell metabolism increase, blood glucose levels

ii. ______- heart and digestive system

iii. Generally the ______effects are longer lasting (NE lasts longer); explains why we need time to “come down” after a stressful situation

  1. ANS Controls

a. Brain stem & spinal cord – heart & breathing rates via ______nerve, gastrointestinal motility, reflex arcs or the spinal cord

b. ______- blood pressure, body temperature, water balance, hunger, thirst, rage, etc.

c. ______- (cerebral cortex) – biofeedback & meditation

  1. Pathology

a. ______- intermittent attacks of vasoconstriction in the extremities usually as a result to exposure to cold = gangrene in some cases due to tissue death

b. ______- from stress, arteriosclerosis, renal disease

c. ______- envisioned as epilepsy of the spinal cord; common in quadra and paraplegics; occurs following injury when reflex action return in an exaggerated state (due to lack of inhibitions by higher centers); trigger is painful skin stimulation or overfilling of a visceral organ