Functional Organization Of Nervous Tissue Chapt. 11

Front 1

What are the functions of the nervous system?
(5)

Back 1

1. Sensory Input (internal and external)

2. Integration--process sensory info and initiate a response

3. Control of muscles and glands

4. Homeostasis--regulate and coordinate activities

5. Mental activity--brain is mission control of consciousness, thinking, memory and emotions

Front 2

Define CNS

Back 2

Brain and spinal cord.

Front 3

Define PNS

Back 3

External to CNS.
Consists of sensory receptors, nerves, ganglia and plexuses.

Front 4

What is a sensory receptor?

Where are they located?

Back 4

endings of nerve cells or separate special cells that detect temperature, pain, touch, pressure, light, sound, odors and other stimuli.

Located in skin, muscles, joints, internal organs and specialized organs like ears and eyes.

Front 5

What is a nerve?

Back 5

bundle of axons and their sheaths. They connect the CNS to sensory receptors, muscles, and glands.

Front 6

What is a ganglion?

Back 6

= knot
a collection of neuron cell bodies located outside the CNS

Front 7

What is a plexus?

Back 7

= braid
extensive network of axons and in some cases neuron cell bodies located outside CNS

Front 8

What are the 2 subcategories of the PNS?

Back 8

Sensory, or afferent division

Motor, or efferent division

Front 9

Which direction do the sensory / afferent division go?

Back 9

From sensory receptors to CNS

Front 10

Which direction do the motor / efferent division go?

Back 10

From CNS to effector organs

Front 11

What are the 2 subdivisions of the motor division?

Back 11

somatic nervous system

autonomic nervous system (ANS)

Front 12

What does the somatic nervous system do?

Back 12

transmits action potentials from the CNS to skeletal muscles.
Voluntary

Front 13

What does the ANS do?

Back 13

transmits action potentials from the CNS to smooth muscle, cardiac muscle and certain glands.

Front 14

What are the subcategories of the ANS?

Back 14

sympathetic division

parasympathetic division

enteric nervous system

Front 15

What is the sympathetic division most active?

Back 15

during physical activity

Front 16

What does the parasympathetic division do?

Back 16

regulates resting or vegetative functions like digesting food or urinating

Front 17

What does the enteric nervous system do?

Back 17

consists of plexuses within the wall of digestive tract (think entrails)

Front 18

Compare the CNS and PNS

Back 18

PNS= detects and sends sensory info to CNS

CNS processes info, initiates response, involves mental processing and sends a response to PNS

Front 19

What is a glial cell or neuroglia?

Back 19

support and protect neurons

Front 20

What is Nissl substance?

Back 20

abundant rough endoplasmic reticulum located in the cell body and dendrites but not axon.
Primary site of protein synthesis in neurons

Front 21

What does a cell body do?

Back 21

recieve stimuli and transmit action potentials to other neurons or to effector organs

Front 22

what does a dendrite do?

Back 22

input part of the neuron.
when stimulated they generate small electic currents which are conducted to cell body

Front 23

What does an axon do?

Back 23

transmits action potentials to other cells

Front 24

What is a multipolar neuron?

Name 2

Back 24

have several dendrites and a single axon

interneuron
motor neuron

Front 25

What is a bipolar neuron?

Where?

Back 25

a single axon and dendrite

found as components of sensory organs

Front 26

What is a unipolar neuron?

What type of neurons are mostly unipolar?

Back 26

have a single axon

most sensory neurons

Front 27

Astrocyte

Back 27

provide structual support for neurons and blood vessels

influence functioning of BBB
by processing substances that go thru it (tight junctions)

isolate damage tissue and limit spread of inflammation

help maintain synaptic function

Front 28

Ependymal cell

Back 28

line the ventricles and central canal of spinal cord.

some specialized to produce cerebrospinal fluid

Front 29

Microglia

Back 29

phagocytize microorganisms, foreign substances and necrotic tissue

Front 30

Oligiodendrocyte

Back 30

forms myelin sheaths around the axons of several CNS neurons

Front 31

What are the glial cells of the CNS?

Back 31

Astrocytes
Ependymal Cells
Microglia
Oligodendrocytes

Front 32

What are the glial cells of the PNS?

Back 32

Schwann cells
Satellite cells

Front 33

Schwann cell

Back 33

forms a myelin sheath around part of an axon of a PNS neuron

Front 34

Satellite cell

Back 34

support and nourish neuron cell bodies within ganglia

Front 35

Myelinated Axon

Back 35

wrapped by several layers of plasma membrane from Schwann cells (PNS) or Oligodendrocytes (CNS).

Spaces between the wrappings are Nodes of Ranvier.

Conduct AP's very fast

Front 36

Unmyelinated Axon

Back 36

rest in invaginations of Schwann cells (PNS) or oligodendrocytes (CNS).

Conduct AP's slowly

Front 37

White matter

Back 37

consist of myelinated axons; it propogates AP's

forms nerve tracts in CNS and nerves in PNS

Front 38

Gray matter

Back 38

consists of collections of neuron cell bodies or unmyelinated axons.

Axons synapse with neuron cell bodies, which are functionally the site of integration in the nervous system.

Forms cortex and nuclei in CNS and ganglia in PNS.

Front 39

Na--K pump

Back 39

moves ions by active transport.
K in, Na out

Front 40

Plasma membrane permeability

Back 40

determined by leak channels and gated ion channels
--more K leak channels
Na leak channels

--gated ion channels are ligand, voltage and other

Front 41

Resting Membrane Potential

Back 41

charge difference across the plasma membrane when cell is in unstimulated state. Inside is negative, outside positive

Due mainly to tendency of K (positive) to diffuse out (down a concentration gradient :) ) which is opposed by the negative charge that develops inside the plasma membrane.

Front 42

Hyperpolarization

Back 42

makes the inside more negative

Front 43

Refractory Period

absolute & relative

Back 43

absolute is the time during an AP when a second stimulus, no matter how strong, cannot make another AP

relative is just after absolute and is the time in which a stronger-than-threshold stimulus can evoke another AP

Front 44

Spacial summation

Back 44

occurs when two of more presynaptic terminals simultaneously stimulate a postsynaptic neuron

2 different action potentials arrive in different dendrites. They summate to create threshold stimulus at trigger zone

Front 45

Temporal summation

Back 45

occurs when two or more action potentials arrive in succession at a single presynaptic terminal

2 action potentials arrive at a single dendrite and together they summate to threshold

Front 46

EPSP's and IPSP's

Back 46

Excitatory and Inhibitory neurons can synapse with the same postsynaptic neuron.
If local depolarizations (EPSP's) override the local hyperpolarizations (IPSP's) to summate to threshold, you get an AP
If vice versa the AP is inhibited.

Front 47

Convergent Pathway

Back 47

many neurons synapsing with a few neurons

Front 48

Divergent pathway

Back 48

few neurons synapsing with many neurons

Front 49

Oscillating circuits

Back 49

neurons arranged in a circular fashion;
collateral branches of postsynaptic neurons synapsing with presynaptic neurons

Front 50

What does a mixed nerve contain?

Back 50

sensory and motor nerve fibers

Front 51

Define somatic nervous system

Back 51

conducts action potentials from CNS to skeletal muscle fibers

Front 52

Definie autonomic nervous system

Back 52

conducts action potentials from the CNS to cardiac muscles, smooth muscles and certain glands

Front 53

What is the sensory division of the peripheral (PNS)?

Back 53

afferent division

Front 54

What is the motor division of the peripheral (PNS)?

Back 54

efferent division

Front 55

What are some things found in the neuron cell body?

Back 55

1. nucleus surrounded by cytoplasm

2. cytoplasm has neurofibrils --cytoskeletal elements of neuron;
support and intracellular transport functions

3. Nissl bodies--(chromatophilic) elaborate endoplasmic reticulum;
involved in metabolic activities of cell

4. Golgi apparatuses, mitochondria and other organelles

Front 56

Define ganglia

Back 56

collections of neuron cell bodies outside the CNS

Front 57

Define plexus

Back 57

(braid) an extensive network of axons and in some cases neuron cell bodies outside the CNS

Front 58

Where are cell bodies of sensory neurons located?

Back 58

in ganglia near spinal cord

Front 59

Where are cell bodies of motor neurons located?

Back 59

within the CNS

Front 60

How many sets of neurons does the ANS have going to effector organs?

Where is the first set?
Where is the second set?

Back 60

2

First set is in within CNS and send their axons to autonomic ganglion

synapse with second neuron cell bodies there and then

second set neurons are post ganglial to effector organ

Front 61

Are there interneurons outisde of the CNS?

Back 61

NO

Front 62

Which division are the sympathetic and parasympathetic from?

Back 62

ANS

Front 63

Name the glial cells of the CNS

Back 63

Astrocytes
Ependymal
Microglia
Oligodendrocyte

Front 64

what is the function of an astrocyte

Back 64

regulate extracellular composition of brain fluid (form tight junctions) in endothelial cells in the capillaries

wall off injury in reactive astrocytosis

release chemicals that promote development of synapses

aid synapses thru synthesis, absorption and recycling of neurotransmitters

Front 65

What is the function of ependymal cells?

Back 65

line ventricles of brain and central canal of s.c.

form choroid plexuses (secrete CSF

cilia move CSF through brain cavities

may have some astrocyte-like functions as well

Front 66

What is the function of microglia?

Back 66

phagocytic response to inflammation.

phagocytize necrotic tissue, microorganisms and other foriegn substances

Front 67

What is the function of oligodendrocytes?

Back 67

cytoplasmic extensions surround and myelinate axons in CNS

Front 68

What are the glial cells of the PNS?

Back 68

Schwann cells

Satellite cells

Front 69

What is the function of a Schwann cell?

Back 69

myelinates pns axons

Front 70

What is the function of a satellite cell?

Back 70

surround neuron cell body in sensory ganglia.

provide support, nutrition and protections

Front 71

Describe a unipolar neuron

Back 71

single process extending from the cell body which later divides a short distance away into central and peripheral processes

Front 72

Describe a bipolar neuron

Back 72

two processes:
1 dendrite
1 axon

Front 73

Describe a multipolar neuron

Back 73

many dendrites with varying branches and a single axon

Front 74

What is a nuclei?

Back 74

Collection of neuron bodies with in the CNS

Front 75

What are Nodes of Ranvier?

Back 75

interruptions in the mylin sheath along the course of a myelinated axon

Front 76

What does white matter consist of?

Back 76

myelinated axons

Front 77

What does gray matter consist of?

Back 77

unmyelinated axons and neuron cell bodies

Front 78

define repolarization

Back 78

membrane potential returns to resting membrane state and is becoming more negative inside

Front 79

What is saltatory propagation?

Back 79

in myelinated axon, a.p. is conducted from one node of Ranvier to another from ionic currents and highly concentrated Na voltage gates

Front 80

What affects the speed of an action potential along an axon?

Back 80

myelination thickness

larger diameter of axon goes faster:
Type A (largest and fastest) 15-120m/s

Type B (medium diameter) 3-15 m/s

Type C (small diameter) 2m/s

Type B, C are ANS--more for homeostasis

Front 81

What's mainly happening during repolarization?

Back 81

Voltage Na gates close.

K voltage gated channels are open

K ions are flowing out of the cell

Front 82

What's going on at resting membrane potential?

Back 82

Voltage gated Na channels are closed

Voltage gated K channels are closed

inactivation gates are open

Front 83

What's going on at depolarization?

Back 83

Voltage-gated Na channels open.

Voltage-gated K channels start to open

Na diffuses in much more than K out, makes inside more positive

Front 84

What is afterpotential?

Back 84

after voltage-gated Na channels are closed K gates are still open, so it becomes more negative inside than at resting

Front 85

What is the threshold of a neuron?

Back 85

voltage that triggers activation of voltage-gated channels.

Front 86

List the characteristics of a local potential

Back 86

Confined to a small region of plasma membrane

Can summate

spread over membrane in decremental fashion

1. variation of amplitude

2. comparatively long duration

3. no refractory period

Front 87

What is the refractory period?

Why is it significant?

Back 87

consists of absolute refractory--complete insensitivity to another stimulus

and

relative refractory period--stronger than threshold stimulus can initiate another action potential.

Significant because it makes the nature of action potential propogation a one-way street

Front 88

What do you get with a supramaximal stimulus?

Back 88

The fastest muscle contraction possible

Front 89

What does a subthreshold stimulus create?

Back 89

a local potential

Front 90

What do endorphins and enkephalins do?

Back 90

when released from inhibitory neurons of axoaxonic synapses reduce perception of pain by inhibiting substance P

Front 91

What does glycine do?

Back 91

a neurotransmitter that causes inhibition of spinal cord motor neurons

Strychnine poisoning blocks glycine receptors so neurons are constantly excited and can cause tetanus of respiratory muscles

Front 92

a decrease in the secretion of dopamine is associated with what?

Back 92

parkinsons disease

Front 93

What is the role of noreprinephrine?

What about amphetamines?

Back 93

excitatory

in the use of amphetamines, the drug blocks reuptake of noreprinephrine or causes their release from synaptic vessicles

Front 94

Describe an electrical synapse

Back 94

gap junctions that allow an ionic current to flow between adjacent cells

Front 95

What is a connexon?

Back 95

protiens in gap junctions

Front 96

What is monoamine oxidase do?

Back 96

MAO is an enzyme that inactivates norepinephrine

Front 97

How many Na and K ions are transported by pump for each ATP molecule?

Back 97

3 Na
2 K

Front 98

How is a local potential created?

Back 98

1. change in membrane permeability

2. ligands bind to their receptors

3. mechanical stimulation

4. changes in the charge across the plasma membrane

Front 99

When does the relative refractory period end?

Back 99

When the K gates close

Front 100

What does catechol-O-methyltransferase break down?

Back 100

norepinephrine

Front 101

Name 11 neurotransmitters and whether or not they are excitatory or inhibitory

Back 101

1. acetycholine
excitatory in CNS
inhibitory or excitatory in ANS

2. Serotonin--biogenic amines
generally inhibitory

3. Dopamine--biogenic amines
excitatory or inhibitory

4. Norepinephrine--biogenic amines
excitatory

5. Gamma-Amino Butyric Acid (GABA)--amino acid
inhibitory on postsynaptic neurons
some presynaptic inhibition in s.c.

6. Glycine--amino acid
inhibitory

7. Glutamate--amino acid
excitatory
major excitatory neurotransmitter of the CNS

8. Adenosine--purine
inhibitory (causes drowsiness, inhibits glutamate during stroke)

9. Substance P--neuropeptide
excitatory (pain)

10. Endorphins--neuropeptide
inhibitory (euphoria and block pain)

11. Nitric Oxide--gas
excitatory (arousal, vasodilation)