Nervous

Question 1

Stimulus for nerve excitation:

Answer 1

1. Chemical
2. Mechanical
3. Electrical.

Question 2

Calcium serves along with (or instead of) sodium in some cells to ………….……

Answer 2

cause most of the action potential.

Question 3

The calcium pump; pumps calcium ions from the interior to the exterior of the cell membrane (or into the endoplasmic reticulum of the cell), creating a calcium ion gradient of about __________fold.

Answer 3

10,000

Question 4

The membrane of the cardiac muscle and smooth muscle cells contains the _______________channels

Answer 4

voltage-gated Ca+ Na+

Question 5

The calcium channels are ______ to become activated,requiring ________ as long for activation as sodium channels

Answer 5

Slow
10 to 20 times

Question 6

A decrease Ca+ concentration in extra cellular fluid (hypocalcaemia) lead to .……………

Answer 6

Increase neuron excitability

Question 7

When ECF Ca+ levels falls 30-50% it’s normal level it leads to………………

Answer 7

To spontaneous discharge in many peripheral nerves causing muscle tetany.

Question 8

action potential occurs only at the………

Answer 8

Nodes of ranvier

Question 9

Yet the action potentials are conducted from node to node; this is called ……….

Answer 9

‘’Saltatory conduction’’

Question 10

Factors which affect the condition velocity:

Answer 10

1.Myelination: myelinated nerve is about 50 times faster.

2.Axon diameter: in small unmyelinated nerve axon the velocity is about 0.5 m\s; while in large myelinated axon is about 100 m\s.

Question 11

in small unmyelinated nerve axon the velocity is about _______ m\s; while in large myelinated axon is about _______m\s.

Answer 11

0.5
100

Question 12

The nerve fiber forms a complex of _____________ that invaginate into the surface of the muscle fiber but lie outside the muscle fiber plasma membrane. The entire structure is called the _____________

Answer 12

branching nerve terminals

motor endplate.

Question 13

The invaginated membrane is called the ____________________ , and the space between the terminal and the fiber membrane is called the ____________________ . At the bottom of the gutter are numerous smaller folds of the muscle membrane called ____________ , which greatly increase the surface area.

Answer 13

synaptic gutter or synaptic trough,

synaptic space or synaptic cleft.

subneural clefts

Question 14

At the nerve terminals there are many ______________ that supply adenosine triphosphate (ATP), the energy source

Answer 14

mitochondria

Question 15

the energy source that used for synthesis of an excitatory transmitter ____________

Answer 15

acetylcholine

Question 16

When a nerve impulse reaches the neuromuscular junction, about _________vesicles of ________ are released from the terminals into the synaptic space.

Answer 16

125

Acetylcholine

Question 17

In the synaptic space are large quantities of the enzyme _________________, which destroys __________

Answer 17

acetyl cholinesterase,

Ach

Question 18

This creates a local positive potential change inside the muscle fiber membrane, called the …………

Answer 18

end plate potential.

Question 19

ach stimulates:

Answer 19

1-stimulate calcium ions to
diffuse
2-stimulate the opening of acetylcholine-gated channels(for sodium)

Question 20

end plate potential initiates an action potential that spreads along the muscle membrane and thus causes…………..…

Answer 20

muscle contraction.

Question 21

______ per cent of the body is skeletal muscle
______percent is smooth and cardiac muscle.

Answer 21

40
10

Question 22

Skeletal muscles are composed of ___________

Answer 22

numerous fibers
(10-80 μm in diameter).

Question 23

___________ Is the cell membrane of the muscle fiber. It consists of a true cell membrane, called the plasma membrane.

Answer 23

Sarcolemma

Question 24

Myofibril composed of about _________myosin filaments
and ________actin filaments.

Answer 24

1500

3000

Question 25

___________ Is the intracellular fluid that fill the spaces between the myofibrils, containing large quantities of K+, Mg+, and P+, plus multiple protein enzymes.

Answer 25

The sarcoplasm:

Question 26

__________________: -It Keeps the Myosin and Actin Filaments in Place . -it’s very springy. -It act as a frame work

Answer 26

Titin Filamentous Molecules

Question 27

All muscle fibers that innervated by a single nerve fiber are called _________

Answer 27

motor unit.

Question 28

the smooth muscle composed of small fibers, _____μm in diameter and only ________μm in length.

Answer 28

1 to 5 μm 20 to 500 μm

Question 29

Types of Smooth Muscle:

Answer 29

(1) multi-unit smooth muscle . (2) unitary (or single-unit) smooth muscle.

Question 30

(In smooth muscle)The contractile process is activated by:

Answer 30

1-Calcium ions 2-Adenosine triphosphate (ATP)

Question 31

Most of the myosin filaments have _______________ ,hinge in one direction and those on the other side hinge in the opposite direction.

Answer 31

side polar” cross-bridges

Question 32

smooth muscle can be stimulated to contract by multiple types of signals:

Answer 32

Nervous signals. Hormonal stimulation. Stretch of the muscle. Several other ways.

Question 33

The ___________________that innervate smooth muscle generally branch diffusely on top of a sheet of muscle fibers.

Answer 33

autonomic nerve fibers

Question 34

autonomic nerve fibers do not make direct contact with the smooth muscle fiber cell membranes but instead form so- called____________

Answer 34

diffuse junctions.

Question 35

The most important transmitter substances secreted by the autonomic nerves innervating smooth muscle are_____________ and______________, but they are never secreted by the same nerve fibers.

Answer 35

acetylcholine norepinephrine

Question 36

___________________is an excitatory transmitter substance for smooth muscle fibers in some organs but an inhibitory transmitter for smooth muscle in other organs.

Answer 36

Acetylcholine

Question 37

Acetylcholine and nor epinephrine excite or inhibit smooth muscle by first binding with a _____________________ on the surface of the muscle cell membrane.

Answer 37

receptor protein

Question 38

Some of the receptor proteins are________________, others are______________.

Answer 38

excitatory receptors inhibitory receptors

Question 39

In the normal resting state, the intracellular potential is usually about_____________mv, which is about 30 mv less negative than in skeletal muscle.

Answer 39

-50 to -60

Question 40

Action potentials occur in unitary smooth muscle (visceral muscle) in one of two forms:

Answer 40

(1) Spike potentials. (2) Action potentials with plateaus.

Question 41

The heart is composed of three major types of cardiac muscles:

Answer 41

• Atrial muscle. • Ventricular muscle. • Specialized excitatory and conductive muscle fibers.

Question 42

The dark areas crossing the cardiac muscle fibers are called_____________

Answer 42

intercalated discs

Question 43

(In heart muscle)The action potential is caused by opening of two types of channels:

Answer 43

(1) Fast sodium channels. (2)Slow calcium channels (calcium-sodium channels)