A&P Lecture Exam 3

neurobiology combines the

behavioral and life sciences.

the nervous system is very

complex!

the nervous system is the foundation of

our conscious experience, personality, and behavior.

the endocrine and nervous systems maintain

internal coordination.

endocrine system-

communicates by means of chemical messengers (hormones) secreted into the blood.

nervous system-

employs electrical and chemical means to send messages from cell to cell.

is this action potential or local potential?

\
produced by gated channels on the soma.

local

is this action potential or local potential?

\
produced by voltage gated channels on the trigger zone and axon.

action

is this action potential or local potential?

\
may be depolarization or hyperpolarization

local

is this action potential or local potential?

\
always begins with depolarization

action

is this action potential or local potential?

\
graded; proportional to stimulus strength

local

is this action potential or local potential?

\
all or none; either does not occur at all or exhibits the same peak voltage regardless of stimulus strength.

action

is this action potential or local potential?

\
reversible; returns to resting membrane potential if stimulation ceases before threshold is reached.

local

is this action potential or local potential?

\
irreversible; goes to completion once it begins.

action

is this action potential or local potential?

\
local; has effect for only a short distance from point of origin.

local

is this action potential or local potential?

\
self-propagating; has effects a great distance from point of origin.

action

is this action potential or local potential?

\
decremental; signal grows weaker with distance.

local

is this action potential or local potential?

\
nondecremental; signal maintains same strength regardless of distance.

action

local potential is either excitatory or inhibitory. explain-

depolarization is excitatory (makes a neuron more likely to fire an action potential.)

\
hyperpolarization is inhibitory (makes a neuron less likely to fire an action potential.)

the dermatome map doesn’t

give exact nerve, but an idea.

dermatome map

a diagram of the cutaneous regions innervated by each spinal nerve.

dermatomes overlap their edges as much as 50%. thats why it is

necessary to anesthetize three successive spinal nerves to produce a total loss of sensation in one dermatome.

dermatome

a specific area of skin that conveys sensory input to a spinal nerve.

reflexes do not involve the ___.

brain

reflexes do involve the __*___.*__

spinal cord

the cerebellum is primarily involved in

muscular control.

complete transection is the

complete severance of the spinal cord.

why would a break in the lumbar region possibly not have any damage to the spinal cord?

the spinal cord ends at about L1-L2

a complete transection (complete severance) of the spinal cord would result in..

\-immediate loss of motor control BELOW the level of injury.

\-spinal shock

\-paralysis

a complete transection (complete severance) of spinal cord above C4 could..

posses the threat of respiratory failure. dead; no repair

paraplegia is

paralysis of both lower limbs.

quadriplegia is

paralysis of all four limbs.

hemiplegia is

paralysis on one side of the body.

paresis is

partial paralysis or weakness of the limbs.

An injury above the cervical plexus results in paralysis of

all four limbs.

An injury to the thoracic region would result in..

nerve damage and leg paralysis.

How many people are paralyzed in the U.S. each year?

10,000 to 12,000

what are the most common spinal cord injuries?

vertebral fractures.

The highest risk group for spinal cord injuries:

males 16-30 years old.

___ of spinal cord injuries occur in automobile or motorcycle accidents.

55%

poliomyelitis causes

destruction of motor neurons and skeletal muscle atrophy from innervation.

poliomyelitis is caused by

poliovirus.

the poliovirus destroys motor neurons in the brainstem and

anterior horn of the spinal cord.

symptoms of poliomyelitis..

muscle pain, weakness, and loss of some reflexes.

the poliomyelitis symptoms lead to..

paralysis, muscular atrophy, and respiratory arrest. (why the iron lung was made.)

poliomyelitis spreads by

fecal contamination of water.

Amyotrophic Lateral Sclerosis (ALS)

Lou Gehrig Disease

destruction of motor neurons and muscular atrophy which leads to death.

sclerosis in ALS

scarring of the lateral regions of the spinal cord.

what are the early signs of ALS?

muscle weakness; difficulty speaking, swallowing, and using hands.

why does ALS happen?

astrocytes fail to reabsorb the neurotransmitter glutamate.

ALS is so hard because

sensory and intellectual abilities remain unaffected, so they know exactly what is happening.

radial nerve injury passes through the

axilla.

why can crutch paralysis result from radial nerve injuries?

the crutches are not set to the correct height which damages the radial nerve from constant pressure.

90% of sciatic nerve injury cases result from

herniated intervertebral disc or osteoporosis of lower spine.

sciatic nerve injury- sciatica

sharp pain that travels from gluteal region along the posterior side of thigh and leg to the ankle.

there are __ pairs of spinal nerves.

31

there are __ pairs of cervical nerves.

8; C1-C8

the first cervical nerve exits between the skull and atlas while the others exit at

intervertebral foramina.

there are __ pairs of thoracic nerves.

12; T1-T12

there are __ pairs of lumbar nerves.

5; L1-L5

there are __ pairs of sacral nerves.

5; S1-S5

there is __ pair of coccygeal nerves.

1; Co 1

a nerve is a

cord-like organ composed of numerous axons bound together by connective tissue. (huge bundle of axons)

epineurium

dense irregular connective tissue that surrounds the whole nerve

endoneurium

loose connective tissue external to neurilemma

perineurium

layers of overlapping squamous cells that wrap the fascicles.

fascicles are

bundles of nerve fibers.

the nerve fibers of the peripheral nervous system are surrounded by

schwann cells that form the neurilemma and myelin sheath around the axon.

the spinal cord communicates with the rest of the body by way of

spinal nerves.

Mixed nerves contain

afferent (sensory) and efferent (motor) fibers.

sensory (afferent) nerves carry

signals from sensory receptors to the CNS.

motor (efferent) nerves carry

signals from CNS to muscles and glands.

Ganglion

a cluster of neurosomas outside of the CNS.

ganglia are enveloped in an

endoneurium continuous with that of the nerve.

There are bundles of nerve fibers within the neursomas leading..

into and out of the ganglion.

the posterior root ganglion is associated with

spinal nerves.

Each spinal nerve is formed from

two roots (proximal branches)

Posterior (Dorsal) Root is

always sensory input to spinal cord.

The anterior (ventral) root is

always motor output out of spinal cord.

The cauda equina is formed from

roots arising from L2 to Co 1

The posterior (dorsal) root ganglion contains the

neurosomas of sensory neurons carrying signals to the spinal cord.

Beyond the vertebrae, the nerve divides into

distal branches. (anterior ramus and posterior ramus)

In the thoracic region, the anterior ramus

gives rise to intercostal nerve.

in other regions, the anterior ramus

form plexuses. (a lot of nerves extend from plexuses)

the anterior ramus takes care of

the front part of the body and nerve begins to split

the posterior ramus takes care of

the back part of the body and innervates the muscles and joints in that region of the spine and the skin of the back.

meningeal branch

reenters the vertebral canal and innervates the meninges, vertebrae, and spinal ligaments.

There is not a ___ plexus.

thoracic

there are __ nerve plexuses.

5

the resting membrane potential is negative due to what?

there are more negatively charged particles on the inside of the membrane than on the outside.

what is true of interneurons?

they are contained entirely within the CNS and carry signals from one neuron to another.

When can a damaged peripheral nerve fiber regenerate?

when the soma is intact and at least some of the neurilemma remains

parkinson disease is caused by what?

degeneration of dopamine-releasing neurons in the brainstem

what describes a reverberating circuit?

there is a prolonged or repetitive effect that lasts until one or more neurons in the circuit fail to fire or until an inhibitory signal from another source stops one of them from firing. Neurons stimulate each other in a linear sequence such as A > B > C > D, but neuron C sends an axon collateral back to A.

what is true about myelin and children?

it is best not to give children under two years of age a low-fat diet because myelin formation requires lipids!

Which term describes all neurons that carry signals towards the CNS?

afferent (sensory)

The enzyme, acetylcholinsterase, located in the synaptic cleft and on the postsynaptic membrane, breaks down..

Ach (acetylcholine) into acetate and choline, thereby stopping the stimulation of a postsynaptic cell.

The physical basis of a memory is a pathway through the brain called a memory trace, in which…

new synapses have formed or existing synapses have been modified to make transmission easier.

Most somatic reflexes have 2 neurons, but some have an

interneuron.

what are the 4 nature of reflexes?

reflexes require stimulation; reflexes are quick; reflexes are involuntary; reflexes are stereotyped.