Human Anatomy Chapter 12

Front 1

STUPID FACT (Just in case): What is ENIAC?

Back 1

the first computer created (weighing 3 tons)

Front 2

the study of the nervous system

Back 2

Neurology

Front 3

What are the two divisions of the Nervous system?

Back 3

Central Nervous System- the brain and spinal cord

Peripheral Nervous system- the nervous system that functions outside the CNS.

Front 4

What three kinds of cells are common in the Peripheral nervous sytem

Back 4

Cranial and spinal nerves (communicate messeges to and from the brain and spine). Also, ganglia (areas where cell bodies are clustered).

Front 5

What are the three overlapping functions of the Nervous system.

Back 5

Sensory- recieve sensory information

Integration- must be able to percieve the sensation and formulate a plan of action.

Motor output- executes a motor response according to the plan created in the integration phase.

Front 6

What does afferent mean? what signals are sent by afferent transport?

Back 6

"Carrying toward" the CNS.

Sensory information is sent to toward the CNS to be integrated.

Front 7

What does efferent mean? what signals are sent by efferent transport?

Back 7

"away from" the CNS.

Motor output is carried away from the CNS to act on the appropriate muscles.

Front 8

The PNS is divided into two classes of signals. What are they?

Back 8

Sensory (afferent) division and Motor (efferent) division

Front 9

Each division of the peripheral nervous system is further subdivided into two classes. What are the four?

Back 9

Somatic Sensory
Somatic Visceral
Motor Sensory
Motor Visceral

Front 10

Both sensory and motor classes of the PNS are subdivided into either somatic or visceral, according to what?

Back 10

the body regions they serve.

Somatic- Skin, skeletal muscle, bones

Visceral- organs in the ventral body.

Front 11

Somatic senory division of the PNS.

- recieves what signal
- in what direction is it travelling
- from what two classes does it recieve information.

Back 11

Sensory

Afferent (Toward CNS)

*General Somatic senses- those stimuli that can be felt on all of the body.
(touch, pain, pressure, temperture, proprioception)

*Special somatic senses- these senses are localized and sensed in a small region of the body (vision, hearing, smelling, balance)

Front 12

Visceral Sensory division of the PNS.

-Recieves what information
- In what direction is it traveling
- from what two classes of sesnses?

Back 12

Sensory

Afferent (Toward the CNS)

*general visceral senses-
stretch, pain, and temperature felt in the viscera. (Nausea and hunger)

*special visceral senses-
sensory information recieved from the localized organs of the body. (TASTE)

Front 13

Somatic Motor division of the PNS.

-Recieves what information
- In what direction is it traveling
- from what two classes of sesnses?

Back 13

Motor

Efferent (Away from the CNS)

Trick question there is only one class.
*General Somatic motor- part of the PNS that signals contraction of skelletal muscles (they are widely found in the body).

Front 14

Visceral motor division of the PNS.

-Recieves what information
- In what direction is it traveling
- from what two classes of sesnses?

Back 14

Motor

Efferent (Away from the CNS)

Only one class.
*General visceral motor-
part of the nervous system that regulates contraction of smooth and cardiac muscle. (AUTOnomic NS).

Front 15

Nervous tissue, despite its complexity, is made up of just two types of cells. What are they?

Back 15

Neurons and supporting cells.

Front 16

Neurons

-defined
-how many
-how are signals produced

Back 16

the basic structural units of the nervous system. highly-specialized cells that propogate electrical signals from one part of their body to another.

1 billion

Action potentials

Front 17

Besides a neurons ability to propogate action potentials, what are 3 special characteristics of neurons?

Back 17

1.) they have EXTREME LONGEVITY (over 100 years)

2.) they DO NOT DIVIDE. (some exceptions- CNS stem cells)

3.) They have EXCEPTIONALLY HIGH METABOLIC RATES.

Front 18

Neuronal cell bodies

-consist of

Back 18

also called a soma, it consists of a single nucleus surrounded by cytoplasm.

Front 19

The Cell body also contains chromatophilic bodies (NIssl) and Neurofibrils. What are their functions?

Back 19

Chromatophillic bodies- "color loving" clusters of rough ER which produce proteins that renew membrane.

Neurofibrils- bundles of intermediate filaments that keep the cell body from being pulled apart from tensile forces.

Front 20

While MOST cell bodies (Soma) are in the CNS, some do lie outside the CNS such as...

Back 20

Ganglion- clusters of cell bodies outside the CNS.

Front 21

What are the two NEURONAL PROCESSES (projections off cell body).

What are their functions

Back 21

Dendrites- function as receptive sites to recieve signals from other neurons. Dendrites then by definition produce AFFERENT SIGNALS ONLY!

Axon- thin long projections. At the meeting between soma and axon is the axon hillock where action potentials are generated. Thus by definition axons produce EFFERENT SIGNALS ONLY!

Front 22

Although axons branch far less than dendrites, they do branch into segments called...

Back 22

axon collaterals.

Front 23

What is the diffrence between a neuron, nerve fiber and nerve?

Back 23

Neuron- the smallest cellular unit of the nervous system.

Nerve fiber- long extension from the cell body (AXON)

Nerve- bundles of nerve fibers outside the CNS (ganglia?)

Front 24

The sie at which neurons communicate is called a...

Back 24

Synapse

Front 25

Most synapses in the nervous system tramsit messages by what process?
Still others use?
Because signals pass across most synapses in one direction only, synapses determine...

Back 25

Chemical transmission

electrical transmission across gap junctions.

the direction of information through the nervous system

Front 26

The neuron that conducts signals toward a synapse is called the...
the neuron that transmits signal away from the synapse is called the...

Back 26

presynaptic neuron; postsynaptic neuron

Front 27

types of synapses

-axodendritic
-axosomatic
-axoaxonic
-dendrodendritic
-dendrosomatic

Back 27

Axodendritic- most common from the axon of one neuron to the dendrite of the other.

Axosomatic- many synapses have these neurons.

The rest are far less common and far less understood.

Front 28

Presynaptic neurons have _________ which are membrane-bound sacs filled with NT.

Back 28

Synaptic vesicles

Front 29

What is the NT released at a neuromuscular junction to cause flexion of a muscle.

Back 29

Acetylcholine

Front 30

What is the function of Cholinesterase?

Back 30

Cholinesterase serves to break down choline and control against unnecessarily long flexion.

Front 31

Why do we say "action potentials on the axon" and not action potentials in the neuron.

Back 31

While the whole neuron can become depolarized, only depolarization (strong enough) at the axon can cause an action potential down the length of the entire axon.

Front 32

graded potentials are recieved where... they are spatially summed up where...

Back 32

the dendrites and the cell body recieve graded depolarizations that cause mild depolarizations these signals are spatially summed at the axon hillock where there either there is enough depolarization to warrant an action potential (ALL OR NONE)

Front 33

What is the purpose of the Sodium potassium pump? what does it actually pump in and out and in what amounts?

Back 33

The purpose of the Sodium potassium pump is to mantain the resting potential of the neuron by pumping out 3 sodium ions (cations) and while pumping in 2 Potassium ions.

Front 34

At resting potential, what forces from the following three ions are acting on the membrane.

-Sodium
-Potassium
-Chlorine

Back 34

Sodium:
-Concentration gradient- IN
- Electrochemical- IN

Potassium:
-Concentration- OUT
- Electrochemical- IN

Chlorine:
-Concentration- IN
-Electrochemical- OUT

Front 35

What then keeps the Sodium ions out of the membrane?

Back 35

The neuronal membrane is impermeable to sodium.

Front 36

What two major effects control the speed of neuronal transmission?

Back 36

-Myelination- makes transmission faster

- diameter of the axon- the wider the axon the faster transmission can take place down its axon.

Front 37

According to Dr. Tillman why are axons with larger diameters able to transmit more quickly?

Back 37

because neurons with larger axons can have more negative charge surrounding the axon (???)

Front 38

Mathematically how does the speed of conduction increase if the number of myelinated fibers doubles? unmyelinated fibers doubles?

Back 38

As one doubles the other doubles.

As on doubles the other will increase by the square root of 2.

Front 39

What is the weak buffalo theory of Alcohol use?

Back 39

Alcohol kills off only the weak neurons (NOT TRUE)

Front 40

what is the so-called "HOMER THEORY" of alcohol and marijuana use?

Back 40

they simply destroy connections between neurons.

Front 41

What are the two realities of using marijuana?

Back 41

1.) Marijuana users have deficits in short term memory.

2.) Marijuana users' brains age quicker than non-users' brains.

Front 42

What are the three STRUCTURAL classes of neurons.
Which is the most common?
What function does each normally serve?

Back 42

Multipolar (99% of all neurons)- have the cell bodies between the dendrites and axon. (MOTOR NEURONS AND INTERNEURONS)

Unipolar- cell body out to the side of axon (Sensory neurons)

Bipolar- cell body in the center of the axon (sensory neurons).

Front 43

Where do the names mutipolar, unipolar and bipolar come from?

Back 43

Multipolars have "multi processes" or multiple projections from the soma.

Bipolar neurons have 2 projections from the soma.

Unipolar neurons have 1.

Front 44

What are the three functional classifications of neurons? What structural class of neurons make them up? what direction do they transmit messges.

Back 44

1.) Sensory neurons are nearly all Unipolar neurons that transmit afferent messages (toward the CNS) from the PNS.

Front 45

Sensory neurons do not have dendrites. WHY?

Back 45

Because the central process caries a signal to the CNS (therefore it is an axon b/c it transmits a signal and toward the CNS). The peripheral process is also considered axonal as it transmits a signal eventhough it is toward the cell body (characteristically of dendrites)

Front 46

what are the three functional classification s of neurons?

Back 46

Sensory neurons, Motor neurons, and inter neurons (mixed neurons.)

Front 47

Motor neurons

-carry afferent/efferent messages.
-motor neurons are made up of what structural class of neurons.
-Motor neurons from junctions with effector cells in order to...

Back 47

Efferent (Away from the CNS)

Multipolar neurons

junctions with effector cells stimulate mucsles to contract or glands to secrete.

Front 48

Interneurons (Mixed neurons)

-lie between
- confound only to
- function to
- made up of what structural class of neurons
-interesting fact.

Back 48

-Sensory and motor neurons

- the CNS

- link together sensory and motor neurons to form complex neuropathways.

- almost all are made up of multipolar neurons.

-Makeup 99% of all the neurons in the body.

Front 49

Sensory neurons

-located
-afferent/efferent transmission
-structural type

Back 49

OUTSIDE THE CNS

Transmit toward the CNS (afferent)

UNIPOLAR NEURONS

Front 50

Interneurons

-location
-afferent/efferent transmission
-structural class of neuron

Back 50

CNS exclusively.

GREAT DIVERSITY. BOTH

MULTIPOLAR.

Front 51

Motor neurons

-location
-afferent/efferent transmission
-structural class of neuron

Back 51

MOSTLY in the CNS

effrerent (away from the CNS)

multipolar

Front 52

Supporting cells are also called neuroglia. There are six classes of neuroglia. What are their names and where can they be found?

Back 52

CNS NEUROGLIA
-Astrocytes
-Microglial
-Ependmal cells
-Oligodendrocytes

PNS support cells
-Schwann cells
-Satelite cells

Front 53

Astrocytes

-CNS/PNS
-Function

Back 53

CNS

bind several neurons to nearby capilaries to supply it with glucose, oxygen, nutrients and removal of wastes.

Front 54

Microglial cells

-CNS/PNS
-Fucntion

Back 54

CNS

Phagocytize any pathogens or debris.

Front 55

Ependymal cells

-CNS/PNS
-Fucntion

Back 55

CNS

Move CSF by ciliary action.

Front 56

Oligodendrocytes

-CNS/PNS
-Fucntion

Back 56

CNS

Provide myelination for neurons in the CNS.

Front 57

Satelite cells

-CNS/PNS
-Fucntion

Back 57

PNS

Physically support cell bodies in ganglia (OUTSIDE THE CNS)

Front 58

Schwann cells

-CNS/PNS
-Fucntion

Back 58

PNS

myelinate the neurons of the perioheral nervous system.

Front 59

How does myelinaion increase the speed at which a neuron can propogate signal?

Back 59

Myelination insluates the neuron from losing electrical potential down its axon. Electrical signal actually occurs only in the NODES OF RANVIER and causes what is called saltatory conduction.

Front 60

What is gray mater vs. white mater?

Back 60

White mater refers to nerves that are myelinated, wheras gray mater refers to unmyelinated nerves.

Front 61

Recall that a neuron is a single cell and several neurons form a fassicle. Several fassicles form a nerve in the PNS.

Each neuron is surrounded by...
Each fassicle is surrounded by...
Each nerve is surrounded by...

Back 61

Endoneurium

Perineurium

Epineurium

Front 62

simple chains of neurons that explain out simplest, relexive behaviors and determine the basic structural plan of the nervous system.

Back 62

Reflex arcs.

it should be mentioned these reactions are unleraned, unpremeditated, and involuntary (NO BRAIN USAGE)

Front 63

The five essentaial components of a reflex arc.

Back 63

1.) receptor- where the stimulus acts
2.) Sensory neuron-transmits the afferent impulses to the CNS
3.) integration center- synapses in the CNS that integrate signal and send back signals
4.) Motor neuron- conducts efferent impulses
5.) Effector- the muscle or gland that reacts to the efferent message.

Front 64

Monosynaptic (stretch reflex)

- how many neurons are required
- Fast/slow
-ipsilateral/contralateral
-example

Back 64

Only 2 neurons (Sensory and motor)~ NO INTERNEURON REQD

FAST

Ipsilateral

Knee-jerk response.

Front 65

Polysynaptic (Withdrawal) reflex

-requires how many neurons
-fast/slow
-ipsilateral/contralateral
-example

Back 65

polysynaptic (w/ interneurons)

Slower than monosynaptic

ipsilateral

touching hot stove

Front 66

Crossed Extensor reflex

-requires how many neurons?
-Fast/slow
-ipsilateral/contralateral
-example

Back 66

polysynaptic

slower than monosynaptic

contralateral and ipsilateral

stepping on a nail.

Front 67

In crossed extensor reflex arcs what key process occurs at the interneuron?

Back 67

The crossing over of information to the conralateral side of the body.

Front 68

What information enters the dorsal spine. What information exits the ventral spine.

Back 68

Afferent sensory information enters the dorsal spines of the spinal column and reaches the brain then exits the ventral spine of the spinal column out to effector cells.

Front 69

Sensory neurons develop from the...

Back 69

neural crest and hence are found OUTSIDE THE CNS.

Front 70

Motor neurons develop from...

Back 70

ventral neuroblasts of the basal plate.

Front 71

Interneurons develop from...

Back 71

dorsally the neuroblasts of the alar plate.

Front 72

Does neural regeneration exist?

Back 72

IF AXONS ONLY are destroyed in the PNS the immune system phagocytically eats distal to the injury and new innervations are made.

In the CNS the neural glial cells never form bands to help guide reinnervation as they do in the PNS. Therefore essentially CNS regeneration is NOT possible.