Pharm Lecture 3 Nmbagents A

Front 1

Soma

Back 1

from the Greek word “body”

Front 2

The nervous system has two major components:

Back 2

CNS - Brain -Spinal cord


PNS (all other neural tissue in the body)
Somatic
Autonomic

Front 3

Somatic nervous system is responsible for: 2x

Back 3

All voluntary muscle contractions
Sensory information processing

Front 4

Somatic nervous system enervates

Back 4

all sensory organs
( eyes, ears, tongue, and skin), as well as all skeletal
muscles.

Front 5

Two branches of the Somatic nervous system

Back 5

Afferent or sensory carries impulses from sense organs
to the CNS
Efferent or motor carries impulses from the CNS to
muscles

Front 6

Motor neuron runs without
interruption from the

Back 6

cord or medulla to the neuromuscular
junction as a large myelinated
axon

Front 7

As the motor neuron approaches the muscle it
branches to contact many
muscle fibers forming a

Back 7

MOTOR UNIT.

Front 8

The motor nerve loses its
myelin and further subdivides
into many

Back 8

presynaptic boutons to terminate on the surface of the muscle fiber the
Motor Endplate

Front 9

Each muscle fiber only receives
one __________

Back 9

synapse.

Front 10

The nerve terminal is covered
with

Back 10

Schwann cells

Front 11

Muscle: three types

Back 11

Smooth
Cardiac
Skeletal

Front 12

Skeletal Made up of

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individual muscle fibers: each fiber is a single cell

Front 13

Skeletal Compose ____% of body mass

Back 13

45

Front 14

_____ skeletal muscles in the human body

Back 14

400

Front 15

Estimated ________ cells are present in these 400 skeletal
muscles

Back 15

250 million

Front 16

Region between a motor neuron
and a muscle cell.

Back 16

Neuromuscular Junction

Front 17

Cell membrane of the neuron and
the muscle fiber are separated by
the

Back 17

SYNAPTIC CLEFT.

Front 18

The ___________ membrane fills the
synaptic cleft.

Back 18

basement

Front 19

basement membrane composed of

Back 19

Composed of collagen and matrix
proteins.

Front 20

basement membrane acts as a

Back 20

support and anchors the
acetylcholinesterase (AChE) found in
the neuromuscular junction

Front 21

Allows rapid diffusion of acetylcholine
(ACh).

Back 21

basement membrane

Front 22

the neurotransmitter at the
neuromuscular junction

Back 22

ACh

Front 23

The muscle surface is corrugated
and on the shoulders of each fold
contain

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the acetylcholine
receptors (nAChR).

Front 24

________________ are located
throughout the muscle membrane

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Na channels

Front 25

ACh is stored in

Back 25

vesicles in
the presynaptic motor
nerve endings

Front 26

ACh is released into

Back 26

synaptic cleft as
packets or quanta.

Front 27

Action potential enters and
depolarizes the

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presynaptic terminal.

Front 28

Depolarization causes ________________ to open

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voltage sensitive Ca P‐type
channels to open

Front 29

Influx of calcium triggers
vesicles to fuse with

Back 29

the
presynaptic membrane

Front 30

ACh is released in the
synaptic cleft by

Back 30

exocytosis.

Front 31

Nicotinic AChR are located
on

Back 31

the presynaptic terminal

Front 32

Nicotinic AChR Are activated by

Back 32

ACh

Front 33

Nicotinic AChR function in a_______________ system

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positive
feedback control

Front 34

feedback control system Maintains the

Back 34

availability of
ACh when demand is high

Front 35

Nicotinic AChR Are involved in the
mobilization of ACh but not

Back 35

the release

Front 36

Block of these receptors may
explain the fade seen in tetanic
and TOF stimulation

Back 36

Nicotinic AChR located
on the presynaptic terminal

Front 37

Are structurally distinct from
the postsynaptic Nicotinic
AChR

Back 37

Nicotinic AChR are located
on the presynaptic terminal

Front 38

Composed of five subunits:
alpha and beta

Back 38

presynaptic terminal Nicotinic AChR

Front 39

Each Nicotinic AChR is a
protein comprised

Back 39

5 polypeptide subunits that
form a ring structure
around a central, funnel
shaped ion channel

Front 40

nAChR (2) Isoforms

Back 40

Junctional or mature - Alpha (2), Beta, Delta, Epsilon

Extrajunctional or
immature Alpha (2), Beta, Delta,
Gamma

Front 41

Motor nerve terminal fits
into the recess of the
motor endplate forming
the

Back 41

postsynaptic junction

Front 42

Postsynaptic Neuromuscular
Junction

ACh once released crosses
the

Back 42

synaptic cleft

Front 43

Postsynaptic Neuromuscular
Junction

ACh binds to

Back 43

nicotinic
AChR on postsynaptic
membranes

Front 44

Binding of ACh at 2 Alpha subunits AChR results
in:

Back 44

A conformational change (depolarization)

Causes a change in membrane permeability to Na and
Ca ions: Na and Ca to move into the myocyte
K to move out
Propagating an action potential, resulting in muscle
contraction

Front 45

conformational change (depolarization)
Causes

Back 45

a change in membrane permeability to Na and
Ca ions:
 Na and Ca to move into the myocyte
 K to move out
 Propagating an action potential, resulting in muscle
contraction

Front 46

Acetylcholinesterase (AChE) Breaks down ACh into acetate and choline by ______________

Back 46

hydrolysis

Front 47

Breaks down ACh into acetate and choline by hydrolysis

Back 47

Acetylcholinesterase (AChE)

Front 48

Found in the junctional cleft attached to the basement
membrane

Back 48

Acetylcholinesterase (AChE)

Front 49

glycoprotein enzyme secreted by the muscle

Back 49

AChE is

Front 50

 Prevents sustained depolarization of the NMJ

Back 50

Acetylcholinesterase (AChE)

Front 51

ACh binds with

Back 51

both alpha subunits

Front 52

ACh not binding to receptor or released after binding is
destroyed by

Back 52

AChE in the junctional cleft

Front 53

ACh is a potent messenger but its actions are short lived being
destroyed in less than

Back 53

1 millisecond after release

Front 54

Choline re‐enters prejunctional membrane to participate in

Back 54

the synthesis of ACh

Front 55

Extrajunctional receptors
Have the structure of immature receptors WHY

Back 55

(epsilon is replaced by gamma subunit)

Front 56

Extrajunctional receptors May precipitate

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hyperkalemic cardiac arrest

Caused by up‐regulation of extra junctional receptors
which are highly sensitive to ACh or succinylcholine
Due to traumatized skeletal muscles, denervation of skeletal
muscles, immobilization, or burns

Front 57

ACh opens the nicotinic receptors allowing

Back 57

Na to rush in
and K to rush out (sustained opening of channel)

Front 58

experimented with curare

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Claude Bernard

Front 59

formed the basis for our ideas of the neuromuscular junction

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curare asphyxiation

Front 60

in 1912 described the use of Curare in humans

Back 60

Laewen (German)