Nervous Tissue

Question 1

what is the structural and function unit of the nervous system

Answer 1

a neuron

Question 2

what is the function of a neuron

Answer 2

to relay signals from internal and external environment

Question 3

where are most neuron cell bodies located

Answer 3

the CNS

Question 4

what parts of neurons can divide

Answer 4

regeneration of axons are possible. neurons in olfactory areas and hippocampus can divide

Question 5

what are the basic cell types of nervous tisxue

Answer 5

neurons and supporting cells

Question 6

what is the function of supporting cells

Answer 6

provide physical support and protection, electrical insulation and metabolic exchange

Question 7

what are the 3 categories of supporting cells

Answer 7

neuroglia in CNS, Schwann cells in PNS, satellite cells in ganglia

Question 8

what is a soma and what does it contain

Answer 8

it is the cell body of the nucleus and it contains the nucleus and cytoplasm

Question 9

what is another word for the cytoplasm of the soma of a neuron

Answer 9

perikaryon

Question 10

what is the nissal substance in a neuron made of

Answer 10

rough ER

Question 11

what is the neurilemma

Answer 11

plasma membrane surrounding the neuron cell

Question 12

what are the contents of a neuron

Answer 12

soma, nissl substance, neurilemma, melanin, lipofusin

Question 13

what are the characteristics of a neuron

Answer 13

1 or more dendrites and a single axon

Question 14

what is the function of dendrites

Answer 14

receive stimuli from other neurons or environment (AFFERENT)

Question 15

what is the function of an axon

Answer 15

transmits stimuli to other neurons or effector cells (EFFERENT)

Question 16

what does the axon arise from

Answer 16

the axon hillock

Question 17

what is the axon hillock

Answer 17

terminates in distal swelling called the terminal bouton

Question 18

what is axonal transport

Answer 18

movement of products down the axon

Question 19

what are the types of axonal transport and what do they carry

Answer 19

-slow axonal transport: cytoskeletal elements
-fast axonal transport: membrane bound organelles

Question 20

what is anterograde transport and what protein does it use

Answer 20

transport from cell body down axon uses kinesin

Question 21

what is retrograde transport and what protein does it use

Answer 21

transport from axon to cell body uses dynein

Question 22

what is a mutli polar neuron

Answer 22

several dendrites surrounding cell body located at the end , single axon, most common

Question 23

what is a bipolar neuron

Answer 23

single dendrite opposite the axon. cell body is in the middle of the axon, dendrites are at the end

Question 24

what is a unipolar axon

Answer 24

no dendrites on cell body, axon only

Question 25

what is a pseudounipolar axon

Answer 25

single dendrite and axon fuse, cell body is off to one side

Question 26

where are sodium and chloride concentrations high

Answer 26

outside the cell

Question 27

where is potassium concentration high

Answer 27

inside the cell

Question 28

describe the steps of depolarization of a membrane

Answer 28

- AP arises in cell body as a result of an afferent stimulus -causes regions of plasma membrane to depolarize - voltage gated Na channels open and Na rushes into the cell - voltage gated K leak channels open and K rapidly leaks out of the cell -membrane potential gets closer to zero

Question 29

what happens inthe absolute refractory period

Answer 29

Na channels close and cant reopen, nerves are unresponsive to stimuli

Question 30

what happens in the relative refractory period

Answer 30

only a strong stimulus can initiate depolarization

Question 31

what marks the end of the refractory period

Answer 31

when Na channels close and voltage gated K channels also close

Question 32

what are synapses

Answer 32

specialized junctions between neurons

Question 33

what are neuromuscular junctions

Answer 33

specialized junction between neuron and effector cell

Question 34

what is entrainment

Answer 34

"muscle memory", the more a pathway is used, the easier it is to access

Question 35

what is the terminal bouton separated from the effector cell by

Answer 35

the synaptic cleft

Question 36

what does the terminal bouton contain

Answer 36

mitochondria and synaptic vesicles containing neurotransmitters

Question 37

what are signaling molecules released from

Answer 37

presynaptic membrnae

Question 38

what 2 neurotransmitters are used in the PNS

Answer 38

acetylcholine and norepinephrine

Question 39

what does the sympathetic nervous system use as a neurotransmitter

Answer 39

noradrenaline (norepinephrine)

Question 40

what are sympathetic neurons called

Answer 40

adrenergic neurons

Question 41

what are parasympathetic neurons called

Answer 41

cholinergic neurons

Question 42

what do parasympathetic neurons use as a neurotransmitter

Answer 42

acetylcholine

Question 43

what do vesicles on the post synaptic membrane contain

Answer 43

hydrolytic and oxidative enzymes

Question 44

what do hydrolytic and oxidative enzymes do in the post synaptic membrane

Answer 44

degrade NT after binding to postsynaptic membrane and thus inactivate it during consecutive impulses to prevent continuous stimulation

Question 45

what types of axons does peripheral nervous tissue have

Answer 45

afferent and efferent axons of somatic or autonomic nerves

Question 46

where are cell bodies of peripheral nerves located

Answer 46

in CNS or ganglia

Question 47

what do peripheral nerves contain

Answer 47

fasicles

Question 48

what are fascicles

Answer 48

a bundle of axons

Question 49

what are schwann cells derived from

Answer 49

neural crest

Question 50

what do schwann cells do

Answer 50

provide metabolic support and electrical insulation

Question 51

describe non myelinated nerve axons

Answer 51

several axons lie in channels within a schwann cell surrounded by a single layer of neurilemma

Question 52

describe a myelinated nerve axon

Answer 52

insulated by many concentric layers of plasma membrane from many schwann cells

Question 53

what forms the myelin sheath

Answer 53

the multiple layers of plasma membrane

Question 54

what are nodes of ranvier

Answer 54

gaps in myelin sheath between adjacent schwann cells. responsible for saltatory conduction

Question 55

where does membrane depolarization occur

Answer 55

only at nodes, not beneath schwann cells

Question 56

why is it helpful to the cell that membrane depolarization only occurs at nodes

Answer 56

it is faster, conserves electrolytes and is energy efficient

Question 57

what are myelinated nerves in the CNS surrounded by

Answer 57

oligodendrocytes

Question 58

describe a myelinated neuron in the CNS

Answer 58

surrounded by an oligodendrocyte. surrounds several nerves with more than one layer of plasma membrane

Question 59

describe the relationship between rate of conduction and the diameter of the axon

Answer 59

the larger the axon the faster the conduction rate

Question 60

what does the endoneurium surround

Answer 60

individual axon and schwann cells

Question 61

what does the perineum surround

Answer 61

fasicles

Question 62

what does the epineurium surround

Answer 62

several fasicles

Question 63

what do blood vessels follow

Answer 63

the epineurium and perineurium

Question 64

where are preganglionic and postganglionic neurons found

Answer 64

in ANS connecting CNS to viscera

Question 65

where are the cell bodies of preganglionic neurons found

Answer 65

grey matter of brain and cord in CNS

Question 66

where are the cell bodies of postganglionic axons found

Answer 66

ganglia

Question 67

what are satellite cells and what do they do

Answer 67

surround soma, derived from neural crest and provide structural and metabolic support

Question 68

where are sympathetic ganglia located

Answer 68

vertebral column

Question 69

where are parasympathetic ganglia located

Answer 69

in or near the effector organ

Question 70

what makes up a sympathetic ganglia

Answer 70

prevertebral and paravertebral ganglia

Question 71

where are prevertebral ganglia located

Answer 71

anterior to spine

Question 72

where are paravertebral ganglia located

Answer 72

sympathetic trunk