Nerve, Muscle, Synapse Lecture 5

Question 1

_______ neurons are always excitatory

Answer 1

Afferent = release glutamate

Question 2

What are the three types of muscle?

Answer 2

Smooth

Cardiac

Skeletal

Question 3

_____ muscle is found in all organs of the body and their contractions act to reduce the size of structures

Answer 3

Smooth muscle is found in all organs of the body and their contractions act to reduce the size of structures

Question 4

What are four functions of smooth muscle?

Voluntary or involuntary?

Answer 4

1. Regulates flow of blood through arteries
2. Moves food through GI tract
3. Expels Urine from the bladder
4. Regulates the flow of air through the lungs

Involuntary

Question 5

Cardiac Muscle:

• _____ muscle found in the walls of the ______
• Propels blood into the _____ and through the _____ of the circulatory system
• _______ control

Answer 5

Cardiac Muscle:

• striated muscle found in the walls of the heart
• Propels blood into the heart and through the blood vessels of the circulatory system
• involuntary control

Question 6

_______ muscle is attached to the skeleton and is also called striated muscle

Answer 6

skeletal muscle is attached to the skeleton and is also called striated muscle

Question 7

Skeletal muscle is under _______ control

Answer 7

voluntary

Question 8

Each muscle cell is surrounded by _______

Answer 8

endomysium

Question 9

_______ surrounds each muscle fiber (cell) and electrically isolates the muscle fibers from one another

Answer 9

endomysium surrounds each muscle fiber (cell) and electrically isolates the muscle fibers from one another

Question 10

Skeletal muscles are electrically insulated from each other by ______

Answer 10

endomysium

Question 11

In order for skeletal muscle cells to contract, each cell must be stimulated by a process of a ________

Answer 11

Motor Neuron

Question 12

Motor neurons leave the spinal cord through the:

Answer 12

Ventral Horn

Question 13

Each ______ neuron innervates a number of muscle cells = impossible to contract just one muscle cell

Answer 13

Each efferent neuron innervates a number of muscle cells = impossible to contract just one muscle cell

Question 14

A motor neuron, its axon and all the muscle fibers it activates makes up the:

Answer 14

Motor unit

Question 15

The ______ is the functional unit of the motor system and represents the SMALLEST increment in force that can be generated

Answer 15

Motor Unit

Question 16

What is the neuromuscular junction

Answer 16

Where the nervous system meets the muscle

Question 17

Neuromuscular junction we have ______-gated chemical synaptic transmission with the post-synaptic cell being the: _____

Answer 17

Neuromuscular junction we have directly-gated chemical synaptic transmission with the post-synaptic cell being the: muscle cell (fibre) HAS ONLY ONE SYNAPSE

Question 18

The region of the muscle fibre plasma membrane that lies directly under the terminal portion of the axon is called:

Answer 18

the motor end plate

Question 19

What is the neurotransmitter used by the efferent (motor) neurons?

Answer 19

Acetylcholine - excitatory

Question 20

Acetylcholin binds to ______ receptors

Answer 20

Ionotropic receptors

Question 21

Ionotropic Receptors: receptors that form _______following the binding of a ______; “______-_______”

Answer 21

Ionotropic Receptors: receptors that form ion channels following the binding of a ligand; ligand-gated ion channels

Question 22

When acetylcholine binds to its receptors it generates a ________of the post-synaptic cell (muscle cell) = opens voltage gated ___ channels

Answer 22

When acetylcholine binds to its receptors it generates a local depolarization of the postsynaptic cell (muscle cell) = opens voltage gated Na+ channels

Question 23

What are 3 Differences between synaptic transmission at a neuromuscular junction and a central synapse?

Answer 23

1. One AP in motor neuron generates one AP in muscle cell (summation required in CNS; no summation in muscle)
2. Each muscle fibre is only innervated by one presynaptic cell
3. No inhibitory transmitters: Only acetylcholine = always excitatory

Question 24

The extracellular space is ______ charged with respect tot he intracellular space

Answer 24

The extracellular space is Positively charged with respect tot he intracellular space

Question 25

The ______ of muscle are extracellular space = positively charged with respect to intracellular space

Answer 25

The _Transverse Tubule (T-tubule)_ of muscle are extracellular space = positively charged with respect to intracellular space

Question 26

As sodium rushes into the muscle cell it generates an \_\_\_\_

Answer 26

Action Potential

Question 27

The ______ surrounds each myofibril within the muscle cell. It is loaded with calcium

Answer 27

Sarcoplasmic Reticulum

Question 28

The action potential causes the release of Ca2+ from the \_\_\_\_\_\_\_

Answer 28

Sarcoplasmic reticulum

Question 29

\_\_\_\_\_\_\_ is the neurotransmitter used at the neuromuscular junction

Answer 29

Acetylcholine

Question 30

How many neuromuscular junctions are there per muscle cell?

Answer 30

ONE

Question 31

Compare excitation-contraction coupling in Skeletal muscle to Cardiac Muscle:

Answer 31

* Cardiac muscle: * L-type Ca2+ channel (modified dihydropyridine receptor) * voltage-gated Ca2+ channel * Calcium binds to Ryanodine receptor (in SR) - ryanodine receptor opens = flows out of sarcoplasmic reticulum * **No physical coupling** * Calcium-dependent calcium release * Skeletal muscle * **Physical coupling** between dihydropyridine receptor (DHP) and ryanodine receptor via foot process * opens calcium channel in sarcoplasmic reticulum

Question 32

Myofibrils are comprised of the contractile elements:

Answer 32

Actin and Myosin (protein filaments)

Question 33

The sarcomere is bound on either side by ____ lines

Answer 33

Z

Question 34

What is the H zone?

Answer 34

Gap between the thick filaments in the sarcomere

Question 35

Although the sarcomere shortens, the length of each _____ does not change. However, the width of the ___ zone changes

Answer 35

Although the sarcomere shortens, the length of each _myofilament_ does not change. However, the width of the _H_ zone changes

Question 36

During muscle contraction, the sarcomere _____ and the H-zone becomes \_\_\_\_\_

Answer 36

During muscle contraction, the sarcomere _shortens_ and the H-zone becomes _narrower_

Question 37

Events at the Neuromuscular Junction 1. The neurotransmitter _______ contained within vesicles is released via ________ into the \_\_\_\_\_\_. Additionally, ____ ions are pumped out of the axon terminal

Answer 37

Events at the Neuromuscular Junction 1. The neurotransmitter _acetylcholine_ contained within vesicles is released via _exocytosis_ into the _synaptic cleft_. Additionally, _Ca2+_ ions are pumped out of the axon terminal

Question 38

Events at the Neuromuscular Junction 2. The depolarization of the ________ initiates an action potential which propagates along the ______ in all directions and down the \_\_\_\_\_\_

Answer 38

Events at the Neuromuscular Junction 2. The depolarization of the _Motor End Plate_ initiates an action potential which propagates along the _Sarcolemma_ in all directions and down the _T-Tubules_

Question 39

Events at the Neuromuscular junction: 3. Action potential causes the release of Ca2+ from the _______ into the cytosol

Answer 39

Events at the Neuromuscular junction: 3. Action potential causes the release of Ca2+ from the _terminal cisternae_ into the cytosol