Topic 7

Question 1

Skeletal mm is formed from a fusion of hundreds of embryonic cells called _________?

Answer 1

Myoblasts

Question 2

Plasma membrane of skeletal mm is called the __________?

Answer 2

Sarcolemma

Question 3

The cytoplasm of skeletal mm cell is ka _________ and it contains structures that allow the cell to generate the ____ needed for contraction.

Answer 3

Sarcoplasm

ATP

Question 4

Structures found in sarcoplasm

Answer 4

Glycogen (glucose polymer)
Mitochondria
Myoglobin (O2 storing protein)

The majority of the sarcoplasm contain myofibrils - rod like cylinders.

Question 5

Each myofibril is composed of __________ and consist of a repeating orderly arrangement of units ka sarcomeres.

What are the proteins they are made from?

Answer 5

Myofilaments

Made from the proteins actin and myosin

Question 6

Is referred to as the thick filament

Answer 6

Myosin

Question 7

Is referred to as the thin filament

Answer 7

Actin

Question 8

The _______ consist of the following pattern; a region of just thin filaments followed by region of thin and thick filaments that overlap

Answer 8

Myofibril

Question 9

This region of thin filament appears light and is referred to as the ___ band

Answer 9

I band

Question 10

This region of overlap appears dark and is referred to as the ____ band

Answer 10

A band

Question 11

The dark A band has a small lighter area in the midsection known as the ___ zone which is vertically bisected by the dark line called the ___ line

Answer 11

H zone

M line

Question 12

The ___ zone contains thick filament only and has no overlap

Answer 12

H zone

Question 13

Each I band is also bisected vertically by a dark line known as the _________

Answer 13

Z disk

Question 14

The basic functional unit of the muscle cell.

___________ is a defined segment of a myofibril.

Answer 14

Sarcomere

Question 15

The linkage between actin and myosin is known as

Answer 15

A cross bridge

Question 16

During the act of muscle contraction, what gets smaller?

Answer 16

The muscle fiber, the myofibrils within the muscle fiber, sarcomeres, distance between the Z discs, I band, H zone

Note: that the A band move closer together but they do not decrease in size

Question 17

What tissue types are found in skeletal muscle?

Answer 17

Skeletal muscle tissue, nervous tissue, epithelial tissue, and connective tissue

Question 18

What tissue surrounds the skeletal muscle? (Epimysium)

Answer 18

Dense irregular CT

Question 19

Within the muscle there are bundles of skeletal muscle fibers known as _________.

Answer 19

Fascicles

Question 20

Each fascicle is surrounded by layer of fibrous CT ka _________

Answer 20

Perimysium

Question 21

What is comprised of the endomysium?

Answer 21

A loose sheath of CT

Question 22

The attachment of a skeletal mm to a bone is usually classified as an ________ (the bone that does not move) or an _______ (the bone that moves)

Answer 22

Origin and insertion

Question 23

The arrival of an action potential at the axon terminal will promote the release of ______________ into the synaptic cleft

Answer 23

Acetylcholine (ACh)

Question 24

ACh Will diffuse across the synaptic cleft and bind to the __________ _________ on the motor and plate

Answer 24

Cholinergic receptors

Question 25

These cholinergic receptors are chemical gated ion channels. The binding of acetylcholine causes these channels to open. This results in the influx of ________ and membrane depolarization known as a graded potential. If it is strong enough it will cause an action potential.

Answer 25

Na+ (sodium)

Question 26

The stimulation of the motor endplate by the acetylcholine is short live it since the synaptic cleft contains the enzyme _________________________ which quickly breaks down acetylcholine.

Answer 26

Acetylcholinesterase

Question 27

The endoplasmic reticulum of the muscle cell is known as

Answer 27

The sarcoplasmic reticulum

Question 28

The action potential will spread down the membrane of the

Answer 28

T tubules

Question 29

The rise in sacroplasmic _______ levels will begin the process of contraction

Answer 29

Ca2+ (calcium)

Question 30

Under resting conditions, myosin cannot latch onto actin and form cross bridges because the myosin-binding sites on actin are blocked by a protein called

Answer 30

Tropomyosin

Question 31

The position of tropomyosin is determined by a protein attached to tropomyosin called

Answer 31

Troponin

Question 32

The calcium that enters the sarcoplasm from the terminal cisternae will bind to

Answer 32

Troponin

Question 33

When calcium binds to troponin it ________ ______. This causes tropomyosin to change positions and exposes the myosin-binding sites on the actin filaments

Answer 33

Changes shape

Question 34

The calcium levels in the sarcoplasm do not stay elevated for long. The membrane of the sarcoplasmic reticulum contains a pump that _______ ____________ calcium back into the sarcoplasmic reticulum

Answer 34

Actively transports

Question 35

What covers the myosin binding sites on actin?

Answer 35

Tropomyosin