Exam 1 Part 3 Nerve supply to skeletal muscle

Question 1

Each muscle is provided with a _____ ____ ___ and a _______ _____ _____

Answer 1

Motor nerve fiber and a sensory nerve fiber

Question 2

Motor nerves transmit:

Answer 2

Efferent/ Motor impulses from the CNS to each individual muscle fiber, the result of which is a motor response (contraction)

Question 3

The single motor neuron (nerve fiber) and the group of muscle fibers is supplies is known as the ____ ___

Answer 3

Motor unit

Question 4

The ____ ___ is the smallest part of the muscle which can contract independently

Answer 4

Motor unit

Question 5

Muscles that carry out precision type of activities contain motor units with:

Answer 5

fewer number of fibers

Question 6

Muscles that carry out non precision type of activities have motor units which can consist of:

Answer 6

thousands of motor fibers

Question 7

Originates in a motor neuron in the ventral horn of the grey matter of the spinal cord

• Continues as the spinal nerves and named peripheral nerves
• The neuromuscular junction
• the sarcolemma of the muscle fiber (terminal end of the unit)

Answer 7

Anatomical parts of the motor unit

Question 8

Physiologically, biochemically and clinically complex portion of the motor unit

Answer 8

Neuromuscular junction

Question 9

Parts of the neuromuscular junction

Answer 9

• Presynaptic portion
• Postsynaptic portion
• Synaptic cleft

Question 10

The nerve ending

Answer 10

Presynaptic portion

Question 11

Sarcolemma of the muscle fiber

Answer 11

Postsynaptic portion

Question 12

Space b/t the pre and post synaptic portions

Answer 12

Synaptic cleft

Question 13

• Most common neuromuscular junction disorder (autoimmune disorder)
• Produces abnormal antibodies which destroy the ACH receptor sites on the sarcolemma of the muscle fibers
• Inherited disorder
• Starts by affecting the muscles supplied by the cranial nerves and may progress to muscles of the extremities

Answer 13

Myasthenia Gravis

Question 14

Patients will suffer from hyperplasia of the _____ _____ or a tumor of the gland

Answer 14

Thymus gland

Question 15

• Example of a drug that is able to complete with ACH molecules in the binding to the ACH receptor sites
• However, its actions are much more prolonged than ACH

Answer 15

Nicotine

Question 16

• Contains both cytotoxins and neurotoxins
• Prevents ACH from binding to the ACH receptor sites
• Do not cause an action potential to occur

Answer 16

Snake venom

Question 17

Ex. include parathion and malathion, which are found in insecticides and are able to inactivate the ACHe
- ACH can no longer be rapidly degraded, resulting in an accumulation of ACH at the postsynaptic portion of the junction

Answer 17

Organophosphates

Question 18

Botulin Toxin is the toxin that is released from the bacteria known as _______ ______, which causes a severe type of food poisoning known as botulism

Answer 18

Clostridium botulinum

Question 19

Toxin blocks the release of ACH from the ________ portion of the neuromuscular junction

Answer 19

Botulin Toxin

Question 20

Usually first affects the muscles supplied by the cranial nerves but can progress to affect limb and respiratory muscles

Answer 20

Botulin Toxin

Question 21

Sensory nerve fibers convey to the CNS _______/_______ impulses which originate within the muscle as a result of a contraction

Answer 21

Afferent/ Sensory

Question 22

In addition to coordination of muscle function, sensory nerve fibers are also involved with:

Answer 22

• Pain

- Proprioception

Question 23

Are a category of sense organs that are found within the musculo-skeletal system

Answer 23

Proprioceptors

Question 24

_____ _____ are an example of proprioceptors found scattered throughout a muscle and are fluid filled sacs.

Answer 24

Muscles spindles

Question 25

Muscle spindles contain specialized muscle fibers known as ______ & ______ muscle fibers

Answer 25

Intrafusal & Extrafusal muscle fibers

Question 26

Have both efferent and afferent nerve fibers associated with them.

Answer 26

Intrafusal muscle fibers

Question 27

Have ONLY efferent nerve fibers associated with them

Answer 27

Extrafusal muscle fibers

Question 28

Muscle spindles and their ________ muscle fibers detect stretch in a muscle

Answer 28

Intrafusal

Question 29

_____ _____ ______ are located in tendons and detect stretch of the tendons, which triggers a reflex which inhibits muscle contractions to avoid injury to the muscle and it tendon

Answer 29

Golgi tendon organs