2nd Semester - Muscular System

Question 1

_ consists of all the muscles of the body. The largest percentage of muscles in the muscular system consists of skeletal muscles, which are attached to bones and enable voluntary body movements.

Answer 1

muscular system

Question 2

The largest percentage of muscles in the muscular system consists of _, which are attached to bones and enable voluntary body movements.

Answer 2

skeletal muscles

Question 3

There are almost _ skeletal muscles in the human body.

Answer 3

650

Question 4

Besides skeletal muscles, the muscular system also includes _ — which makes up the walls of the heart — and _, which control movement in other internal organs and structures.

Answer 4

cardiac muscle; smooth muscles

Question 5

What are the organs, muscles, mainly composed of?

Answer 5

• muscle cells | muscle fibers (mainly in skeletal and cardiac muscle)
• myocytes (mainly in smooth muscle)

Question 6

_ are long and thin cells that are specialized for the function of contracting.

Answer 6

Muscle cells

Question 8

They contain _ that slide over one another using energy in ATP. The sliding filaments increase the tension in — or shorten the length of — muscle cells, causing a contraction.

Answer 8

protein filaments

Question 9

_ are responsible for virtually all the movements of the body, both inside and out.

Answer 9

Muscle contractions

Question 10

_ are attached to the bones of the skeleton. When these muscles contract, they move the body. They allow us to use our limbs in a variety of ways, from walking to turning cartwheels. Skeletal muscles also maintain posture and help keep balance.

Answer 10

Skeletal muscles

Question 11

Smooth muscles in the walls of blood vessels contract to cause _, which may help conserve body heat.

Answer 11

vasoconstriction

Question 13

Relaxation of these muscles causes _, which may help the body lose heat.

Answer 13

vasodilation

Question 14

In the organs of the digestive system, smooth muscles squeeze food through the gastrointestinal tract by contracting in sequence to form a wave of muscle contractions called _. _ of smooth muscles also moves urine through the urinary tract.

Answer 14

peristalsis

Question 15

_ is found only in the walls of the heart. When cardiac muscle contracts, it makes the heartbeat. The pumping action of the beating heart keeps blood flowing through the cardiovascular system.

Answer 15

Cardiac muscle tissue

Question 16

Muscles can grow larger, or _. This generally occurs through increased use, although hormonal or other influences can also play a role.

Answer 16

hypertrophy

Question 17

The increase in _ during puberty, for example, causes a significant increase in muscle size. Physical exercise that involves weight-bearing or resistance training can increase the size of skeletal muscles in virtually everyone. Exercises (such as running) that increase the heart rate may also increase the size and strength of cardiac muscle.

Answer 17

testosterone

Question 18

The _, in turn, is the main determinant of muscle strength, which may be measured by the amount of force a muscle can exert.

Answer 18

size of a muscle

Question 19

Muscles can also grow smaller, or _, which can occur through lack of physical activity or from starvation. People who are immobilized for any length of time — for example, because of a broken bone or surgery — lose muscle mass relatively quickly.

People in concentration or famine camps may be so malnourished that they lose much of their muscle mass, becoming almost literally just “skin and bones.” Astronauts on the International Space Station may also lose significant muscle mass because of weightlessness in space

Answer 19

atrophy

Question 20

Many diseases, including cancer and _, are often associated with muscle atrophy.

Answer 20

AIDS

Question 21

As people grow older, there is a gradual decrease in the ability to maintain skeletal muscle mass, known as _. The exact cause of _ is not known, but one possible cause is a decrease in sensitivity to growth factors that are needed to maintain muscle mass. Because muscle size determines the strength, muscle atrophy causes a corresponding decline in muscle strength.

Answer 21

sarcopenia

Question 22

In both hypertrophy and atrophy, the number of muscle fibers does not change. What changes the size of the muscle fibers?

Answer 22

When muscle hypertrophy happens, the individual fibers become wider.

When muscle atrophy happens, the fibers become narrower.

Question 23

Muscles cannot contract on their own. Skeletal muscles need stimulation from _ in order to contract.

Answer 23

motor neurons

Question 24

The point where a motor neuron attaches to a muscle is called a _.

Answer 24

neuromuscular junction

Question 25

Involuntary contractions of smooth and cardiac muscles are also controlled by _, but in the case of these muscles, the impulses come from the autonomic nervous system (smooth muscle) or specialized cells in the heart (cardiac muscle). Hormones and some other factors also influence involuntary contractions of cardiac and smooth muscles. For example, the fight-or-flight hormone adrenaline increases the rate at which cardiac muscle contracts, thereby speeding up the heartbeat.

Answer 25

electrical impulses

Question 26

Muscles cannot move the body on their own. They need the skeletal system to act upon. The two systems together are often referred to as the _.

Answer 26

musculoskeletal system

Question 27

Skeletal muscles are attached to the skeleton by tough connective tissues called _. Many skeletal muscles are attached to the ends of bones that meet at a joint. The muscles span the joint and connect the bones. When the muscles contract, they pull on the bones, causing them to move. The skeletal system provides a system of levers that allow body movement. The muscular system provides the force that moves the levers.

Answer 27

tendons

Question 28

Muscles play a part in every function of the body. The muscular system is made up of over 600 muscles. These include three muscle types: ___.

Answer 28

smooth, skeletal, and cardiac

Question 29

Only skeletal muscles are _, meaning you can control them consciously. Smooth and cardiac muscles act _.

Answer 29

voluntary; involuntarily

Question 30

Your skeletal muscles are responsible for the movements you make. Skeletal muscles are attached to your bones and partly controlled by the central nervous system (CNS).

Answer 30

Mobility

Question 31

_ cause short bursts of speed and strength.

Answer 31

Fast-twitch skeletal muscles

Question 32

_ function better for longer movements.

Answer 32

Slow-twitch muscles

Question 33

The involuntary cardiac and smooth muscles help your heart beat and blood flow through your body by producing electrical impulses. The cardiac muscle (myocardium) is found in the walls of the heart. It’s controlled by the autonomic nervous system responsible for most bodily functions.

Answer 33

Circulation

Question 34

Your _ are made up of smooth muscles, and also controlled by the autonomic nervous system.

Answer 34

blood vessels

Question 35

Your diaphragm is the main muscle at work during quiet breathing. Heavier breathing, like what you experience during exercise, may require accessory muscles to help the diaphragm. These can include the abdominal, neck, and back muscles.

Answer 35

Respiration

Question 36

_ is controlled by smooth muscles found in your gastrointestinal tract.

Answer 36

Digestion

Question 37

The digestive tract comprises the:

Answer 37

➢ Mouth ➢ Esophagus ➢ Stomach ➢ small and large intestines ➢ rectum ➢ anus The digestive system also includes the liver, pancreas, and gallbladder.

Question 38

Smooth and skeletal muscles make up the urinary system.

Answer 38

Urination

Question 39

The urinary system includes the:

Answer 39

➢ kidneys ➢ bladder ➢ ureters ➢ urethra ➢ penis or vagina ➢ prostate

Question 40

Smooth muscles are found in the uterus. During pregnancy, these muscles grow and stretch as the baby grows. When a woman goes into labor, the smooth muscles of the uterus contract and relax to help push the baby through the vagina.

Answer 40

Childbirth

Question 41

Your eye sockets are made up of six skeletal muscles that help you move your eyes. And the internal muscles of your eyes are made up of smooth muscles. All these muscles work together to help you see. If you damage these muscles, you may impair your vision.

Answer 41

Vision

Question 42

The skeletal muscles in your core help protect your spine and help with stability. Your core muscle group includes the abdominal, back, and pelvic muscles. This group is also known as the trunk. The stronger your core, the better you can stabilize your body. The muscles in your legs also help steady you.

Answer 42

Stability

Question 43

Your skeletal muscles also control posture. Flexibility and strength are keys to maintaining proper posture. Stiff neck muscles, weak back muscles, or tight hip muscles can throw off your alignment. Poor posture can affect parts of your body and lead to joint pain and weaker muscles.

Answer 43

Posture

Question 44

Posture includes these parts:

Answer 44

➢ shoulders ➢ spine ➢ hips ➢ knees

Question 45

What are the main functions of the muscular system?

Answer 45

1. Mobility 2. Circulation 3. Respiration 4. Digestion 5. Urination 6. Childbirth 7. Vision 8. Stability 9. Posture

Question 46

The following conditions can affect your muscular system:

Answer 46

➢ myopathy (muscle disease) ➢ muscular dystrophy ➢ multiple sclerosis (MS) ➢ Parkinson’s disease ➢ fibromyalgia