paano magflex imong biceps?

Question 1

are made up of several hundred to several thousand of parallelly arranged myofibrils having the special function of contraction.

Answer 1

Muscle fibers

Question 2

The increased _____________ level causes the synaptic vesicles to fuse with the presynaptic membrane; the fused synaptic vesicle opens and releases the acetylcholine into the synaptic cleft by exocytosis.

Answer 2

intracellular Ca++

Question 3

is accomplished by a sliding together or telescoping of the interdigitating thick and thin filaments and as a result narrowing and eventual disappearance of the H zone and shortening of, I band happen.

Answer 3

Muscle contraction

Question 4

When the ____ concentration drops in the sarcoplasm, the strong affinity of these ion for troponin `C’ is lost. This causes the movement of tropomyosin molecule to its original position to cover the active binding site, the “G” actin results in relaxation of the muscle.

Answer 4

Ca++

Question 5

Muscle cells also contain a special structure called ____________________ which has two sets of tubules. Longitudinal tubules (L-Tubules) and transverse tubules (T-Tubules).

Answer 5

sarcotubular system

Question 6

diffusion of sodium ions into the muscle cell generating local potential change called __________.

Answer 6

end plate potential

Question 7

Presence of the __________________ in the presynaptic nerve terminal permits the transmission of action potential unidirectionally from the motor nerve to the skeletal muscle fiber.

Answer 7

neurotransmitter

Question 8

The released ___________________ diffuses across the synaptic cleft, reaches the postsynaptic membrane (sarcolemma), and binds with acetylcholine-specific receptors. This causes opening of ligand-gated ion channels in the sarcolemma. And diffusion of sodium ions into the muscle cell generating local potential change called end plate potential.

Answer 8

acetylcholine

Question 9

represents partial overlapping the myosin filaments with actin filament.

Answer 9

“H” zone

Question 10

is a large protein molecule composed of 6 polypeptide chains 2 of which are 100% α – helically exist. Well distinct Head with binding site for Actin and is equipped with ATPase system. They have Hinges to alter the position of the head. The twisted end shows the tail

Answer 10

Myosin

Question 11

Depolarization in the end plate potential opens ______________________________ at the postsynaptic membrane and leads to the generation of an action potential on the muscle cell membrane. Presence of the neurotransmitter in the presynaptic nerve terminal permits the transmission of action potential unidirectionally from the motor nerve to the skeletal muscle fiber.

Answer 11

voltage-gated Na+ channels

Question 12

is a neuromuscular disorder in which autoantibodies are produced against acetylcholine receptors. Hence, neuromuscular transmission is impaired and leads to paralysis.

Answer 12

Myasthenia gravis

Question 13

Cross striated in structure, Involuntary in function, Under autonomic nervous system control.

Answer 13

Cardiac muscle

Question 14

Skeletal muscle cells are multinucleated and an average of 100 – 200 nuclei per cell. Because skeletal muscle cell in a mature muscle originates form fusion of 100 – 200 different embryonic muscle cells called _____________, with each contributing one nucleus.

Answer 14

myoblasts

Question 15

It is composed of three proteins; actin, tropomyosin and troponin.

Answer 15

Actin Filament

Question 16

The heads of the myosin molecules hang outward to the sides of the body. Along with the head, ________ extends outward from the body of the myosin filament.

Answer 16

arm

Question 17

When a muscle is stimulated, a high concentration of Ca++ ions is released from the cisternae into the sarcoplasm. The Ca++ ions readily combine with the ___________ of the TT – complex causes conformational change in the troponin complex and moves the tropomyosin molecule deeper into the groove between two actin strands.

Answer 17

troponin `C’

Question 18

molecules are rod shaped they lie in the 2 grooves of the double stranded actin filament and aggregate end to end to produce two strands of tropomyosin running enter length of this filament.

Answer 18

Tropomyosin

Question 19

The center of I bands contain a dark line called the _________________ where the ends of the actin filaments are attached. The z-discs are filamentous proteins, located in a vertical position in the myofibril.

Answer 19

“z line” or “z disc”

Question 20

No cross striations found, poorly organized Actin and Myosin filaments. Ratio of Actin and Myosin is 15:1, Absence of Troponin complex.

Answer 20

Smooth muscle

Question 21

In _____________________ instead of troponin another regulatory protein “calmodulin” reacts with four Ca++ ions. The calmodulin-Ca++ complex activates myosin kinase and Ca++ dependent phosphorylation of light chain myosin molecule to activate myosin cross-bridge reactions.

Answer 21

smooth muscle

Question 22

mitochondria of muscle cell.

Answer 22

Sarcosomes

Question 23

has a very high affinity for calcium ions. Each molecule can bind up to 4 Ca++ ions. The combination of Ca++ ions with troponin is the triggering factor to initiate muscular contraction.

Answer 23

Troponin “C”

Question 24

It is a double helix structure formed by the basic unit “F” actinmolecule. Each strand of F-actin helix has hundreds of “G” actin molecules which have ADP molecule.

Answer 24

Actin

Question 25

The electron microscopic view of light bands indicates ___________ represented as “I” bands because they are isotropic to polarized light.

Answer 25

actin filaments

Question 26

The flexible points of the arm are _______ which allow the head to be extended outward or brought closer to the body of myosin filament.

Answer 26

hinges

Question 27

Each ______ possesses the contractile proteins myosin (thick) and actin (thin) myofilaments results in regular repetition of dark and light bands in the skeletal and cardiac muscles.

Answer 27

myofibril

Question 28

During resting stage, it covers “G” actin and prevents the binding of myosin head with the binding site.

Answer 28

Tropomyosin

Question 29

When the action potential reaches the presynaptic terminal of the motor neuron, the depolarization opens _____________________; and extracellular Ca ++ diffuses into the presynaptic nerve cytoplasm.

Answer 29

voltage-gated Ca++ channels

Question 30

is the fluid present inside each fiber in which the organelles like sarcosomes(mitochondria), sarcoplasmic reticulum and myofibril are suspended.

Answer 30

Sarcoplasm

Question 31

The presence of______________________ in actin filament inhibits the binding reaction of actin with myosin. In a relaxed muscle fiber, physically covers the “G” actin for binding with myosin.

Answer 31

troponin and tropomyosin (tt-complex)

Question 32

Present parallel to myofibrils. At both the ends of the tubule, bulbous structures known as terminal cisternae function as a storage place for the Ca++ ions and play a key role in muscle contraction.

Answer 32

L Tubule system

Question 33

On stimulation, the muscle contracts between one fixed and one moveable points (e.g., Lifting the weight) shows shortening in length, but the tension on the muscle remains constant.

Answer 33

Isotonic contraction

Question 34

The motor neuron branches at its end and each branch comes into a close opposition with the skeletal muscle at a specialized area called the ______________________

Answer 34

neuromuscular junction or motor end plate.

Question 35

Cytoplasm of the muscle cell is called sarcoplasm which contains ________. It is an O2 storage protein and has a higher affinity for O2 than hemoglobin. Binds with O2 from oxygenated hemoglobin in the blood stream.

Answer 35

myoglobin

Question 36

readily binds with actin and tropomyosin. In resting muscles, they inhibit ATPase activity in myosin head.

Answer 36

Troponin I

Question 37

The _______________ is the terminal portion of the axon of the motor neuron; the extends from the CNS to the muscle cell.

Answer 37

presynaptic knob

Question 38

It is a paired cisternae and a “T” tubule in between the cisternae. One T- tubule and 2 lateral cisternae associated with it forms a ‘Triad’. They have remarkable ability to accumulate Ca2+ against a concentration gradient.

Answer 38

Triad

Question 39

Band of the myofibril is a dark line seen at the center of “A” band is rarely seen in normally functioning muscle. It is well marked only during relaxation beyond physiological limit.

Answer 39

H Band

Question 40

Cross striated and attached to skeleton, 40% of the total body weight, Voluntary neural control.

Answer 40

Skeletal muscles

Question 41

endoplasmic reticulum of muscle cells.

Answer 41

Sarcoplasmic reticulum

Question 42

is the first event of action potential is characterized by rapid increase in the permeability to Na+ ions (5000 folds) to interior of the cell generating more positive electrical potential inside of the cell.

Answer 42

Depolarization stage

Question 43

Isometric contraction Muscle contraction without shortening in length that occurs during the manifestation of the process of muscle contraction.

Answer 43

Isometric contraction

Question 44

This synapse has a presynaptic membrane, a narrow space between the nerve and muscle, called ________ and a post synaptic membrane sarcolemma.

Answer 44

synaptic cleft

Question 45

The T system consist of set of tubules formed by the invaginations of the _________________. This tubule run perpendicular to the long axis of the muscle cell and lie between the cisternae of two successive “L” tubules.

Answer 45

plasmalemma

Question 46

is the resting cell membrane with a normal negative resting membrane potential.

Answer 46

Polarized membrane

Question 47

The postsynaptic cell membrane has a series of invaginations called _______________ that increase the surface area of the postsynaptic membrane. Acetylcholine receptors are located on the postsynaptic membrane at the entrance of these area.

Answer 47

junctional folds

Question 48

Muscles are surrounded by a sheet of connective tissue called _____________ (site for fat deposition).

Answer 48

epimysium

Question 49

Muscle cell is covered by the plasma membrane called __________

Answer 49

sarcolemma

Question 50

The protruding arms and heads together are called _____________. There are no cross-bridges at the center of the myosin filament.

Answer 50

cross-bridges

Question 51

The ___________ possess ATPase enzyme, which helps to cleave the ATP to release energy for the contraction process. The binding ability of the myosin head with the binding site G actin is regulates by ATPase.

Answer 51

myosin head

Question 52

Myosin has enzymatic ability to split ATP and release energy. Enzyme is myosin ATPase. _______________ are required for activating these enzymes

Answer 52

Actin and Mg2+

Question 53

provides the active binding site to myosin head. Tropomyosin and Troponin are the polymer of actin.

Answer 53

G-actin

Question 54

has high affinity to tropomyosin and binds the troponin complex with tropomyosin.

Answer 54

Troponin T

Question 55

Small projections of myosin filaments called ______________ protrude out of the myosin filaments along the entire length except the very center of the myosin filament.

Answer 55

cross-bridges

Question 56

Portion of the myofibril between two successive z-discs is called as “____________”. The sarcomere is the physiological contractile unit of muscle.

Answer 56

sarcomere

Question 57

The __________ are located at the junction of “A” and “I” bands which pass through the fibers, open into the inter-fiber space, permits the flow of extracellular fluid.

Answer 57

T tubules

Question 58

These vesicles are in clustered located very close to the presynaptic membrane. ___________________ is synthesized in the cytoplasm of the nerve terminal and stored in the synaptic vesicles.

Answer 58

Acetylcholine

Question 59

is a narrow space of 20 to 30nm wide separates the presynaptic membrane and postsynaptic sarcolemma membranes. The synaptic cleft is filled with extracellular fluid and spongy reticular filaments called basal lamina.

Answer 59

Synaptic cleft

Question 60

cell membrane of muscle cell.

Answer 60

Sarcolemma

Question 61

More ellipsoidal or globular molecule, binds to a particular site on the tropomyosin molecule. Troponin has an important role as switch for muscle contraction. It has got 3 sub unit polypeptide chains

Answer 61

Troponin

Question 62

much smaller molecule than myosin and contains only one polypeptide chain per molecule. Found in aggregations which form a double stranded helical filament.

Answer 62

Actin

Question 63

arise and divide muscle into several small bundles. This contains blood vessels, nerves and muscles spindles. It envelopes a bundle of 50 to 200 fibers.

Answer 63

Perimysium

Question 64

The dark bands of myosin are represented by ____________, which are anisotropic to polarized light.

Answer 64

A Band

Question 65

It is a complex made up of 3 proteins namely Troponin “T”, Troponin “I”, and Troponin “C”.

Answer 65

Troponin

Question 66

The ___________ contains a large number of vesicles called synaptic vesicles; contain the excitatory neurotransmitter substance acetylcholine.

Answer 66

axoplasm

Question 67

In a muscle, the muscle fibers are arranged as number of muscle bundles known as “___________”.

Answer 67

fasciculus

Question 68

The synaptic cleft contains an enzyme, _____________________, to hydrolyze acetylcholine.

Answer 68

acetylcholinesterase

Question 69

This channel has only one gate at the interior of the membrane. It may either close or open to the interior of the cell. During resting stage this gate is inactivated and prevents the passage of K+ ion to the exterior of the cell through this channel system.

Answer 69

Voltage – gated potassium channel

Question 70

The ______________________ have two gates, the external gate or activation gate which opens to outside of the cell. The other gate is at the interior end and opens to inside of the cell referred as internal gate or inactivation gate.

Answer 70

voltage – gated Na+ channels