Chapter 15 - Muscular System

Question 1

What Is the Muscular System?

Answer 1

Themuscular systemconsists 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. There are almost 650 skeletal muscles in the human body.

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

Question 2

what are muscles?

Answer 2

Muscles are organs composed mainly of muscle cells, which are also calledmuscle fibers(mainly in skeletal and cardiac muscle) ormyocytes(mainly in smooth muscle). Muscle cells are long, thin cells that are specialized for the function of contracting. They contain protein filaments 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. Muscle contractions are responsible for virtuallyallthe movements of the body, both inside and out.

Question 3

What is peristalsis?

Answer 3

A wave of muscle contractions used to moved food through the gastrointestinal tract.

Question 4

What is hypertrophy?

Answer 4

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

Question 5

What is atrophy?

Answer 5

Muscles can also grow smaller, oratrophy, whichcan occur through lack of physical activity or from starvation.

Question 6

What is sarcopenia?

Answer 6

As people grow older, there is a gradual decrease in the ability to maintain skeletal muscle mass, known assarcopenia.The exact cause of sarcopenia 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 strength, muscle atrophy causes a corresponding decline in muscle strength.

Question 7

In both hypertrophy and ___, the ___ of muscle ____ does not change. What changes is the ___ of the muscle ___.

Answer 7

apertrophy, size, fibers, size, fibers

Question 8

What the heck is a neuromuscular junction?

Answer 8

The point where a motor neuron attaches to a muscle.

Question 9

Interplay between skeltal and muscular systems

Answer 9

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 themusculoskeletal system. Skeletal muscles are attached to the skeleton by tough connective tissues calledtendons. 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.

Question 10

KNow this AboUt MUScleS

Answer 10

Skeletal muscles need the stimulus of motor neurons to contract, and to move the body, they need the skeletal system to act upon. Involuntary contractions of cardiac and smooth muscles are controlled by special cells in the heart, nerves of the autonomic nervous system, hormones, or other factors.

Question 11

WHAT IS MUSCLE TISSUE?

Answer 11

Muscle tissueis a soft tissue that makes up most of the tissues in the muscles of the human muscular system. Other tissues in musclesareconnective tissues, such as tendons that attach skeletal muscles to bones and sheaths of connective tissues that cover or line muscle tissues. Only muscle tissue per se, however, has cells with the ability to contract.

There are three major types of muscle tissues in the human body: skeletal, smooth, and cardiac muscle tissues.

Question 12

What is skeletal muscle tissue?

Answer 12

Skeletal muscleis muscle tissue that is attached to bones bytendons,which are bundles of collagen fibers

Question 13

big GOOD INFO ABOUT SKELETAL MUSCLE STRUCTURE

Answer 13

Each skeletal muscle consists of hundreds — or eventhousands— of skeletal muscle fibers, which are long, string-like cells.As shown in the figurebelow, skeletal muscle fibers are individually wrapped in connective tissue calledendomysium.The skeletal muscle fibers are bundled together in units calledmuscle fascicles, whichare surrounded by sheaths of connective tissuecalledperimysium.Each fascicle contains between ten and 100 (or even more!) skeletal muscle fibers. Fascicles, in turn, are bundled together to form individual skeletal muscles, which are wrapped in connective tissue calledepimysium.The connective tissues in skeletal muscles have a variety of functions. They support and protect muscle fibers, allowing them to withstand the forces of contraction by distributing the forces applied to the muscle. They also provide pathways for nerves and blood vessels to reach the muscles. In addition, the epimysium anchors the muscles to tendons.

Question 14

What is endomysium?

Answer 14

Connective tissue that wraps around skeletal muscle fibers.

Question 15

What are muscle fascicles?

Answer 15

Units of bundled skeletal muscle fiber.

Question 16

What is Perimysium
vs
Epimysium?

Answer 16

Perimysium - sheaths of connective tissue that surround muscle fascicles.

Epimysium - A bundle of fascicles that constitutes a skeletal muscle.

Question 17

Structure of a muscle fiber

Answer 17

muscle fiber consists of a bundle of myofibrils, which are themselves bundles of protein filaments. These protein filaments consist of thin filaments of the protein actin — which are anchored to structures called Z discs — and thick filaments of the protein myosin. The filaments are arranged together within a myofibril in repeating units calledsarcomeres,which run from one Z disc to the next. The sarcomere is the basic functional unit of skeletal (and cardiac) muscles.

Question 18

What is sarcoplasmic reticulum?

Answer 18

A specialized type of endoplasmic reticulum that forms a network around each myofibril.

Question 19

Difference between slow and fast twitch skeletal muscle fibers

Answer 19

Type I: Slow-twitch muscle fibers - are dense with capillaries and rich in mitochondria and myoglobin, which is a protein that stores oxygen until needed for muscle activity. Relative to fast-twitch fibers, slow-twitch fibers can carry more oxygen and sustain aerobic (oxygen-using) activity. Slow-twitch fibers can contract for long periods of time, but not with very much force. They are relied upon primarily in endurance events, such as distance running or cycling.

Type II: Fast-twitch muscle fibers - contain fewer capillaries and mitochondria and less myoglobin. This type of muscle fiber can contract rapidly and powerfully, but it fatigues very quickly. Fast-twitch fibers can sustain only short, anaerobic (non-oxygen-using) bursts of activity. Relative to slow-twitch fibers, fast-twitch fibers contribute more to muscle strength and have a greater potential for increasing in mass. They are relied upon primarily in short, strenuous events, such as sprinting or weight lifting.

Question 20

Fast twitch vs slow twitch muscle fibers (simple)

Answer 20

Fast
-Bursts of energy
-Short term
-Less capillaries and mitochondria and myoglobin

Slow
-Endurance
-Long term
-Dense with capillaires and rich in motochondria and myoglobin

Question 21

What is smooth muscle tissue?

Answer 21

Smooth muscleis muscle tissue in the walls of internal organs and other internal structures such as blood vessels. When smooth muscles contract, they help the organs and vessels carry out their functions.

Question 22

Structure of smooth muscle

Answer 22

The cells that make up smooth muscle are generally calledmyocytes.Unlike the muscle fibers of striated muscle tissue, the myocytes of smooth muscle tissue do not have theirfilaments arranged in sarcomeres. Therefore, smooth tissue is not striated. However, the myocytes of smooth muscle do contain myofibrils, which in turn contain bundles of myosin and actin filaments.

Question 23

Function of smooth muscle:

Answer 23

-Sustain long-term contractions
-Stretch and maintain contractile function

Question 24

Locations of smooth muscle:

Answer 24

Walls of organs of the gastrointestinal tract (such as the esophagus, stomach, and intestines), moving food through the tract by peristalsis

Walls of air passages of the respiratory tract (such as the bronchi), controlling the diameter of the passages and the volume of air that can pass through them

Walls of organs of the male and female reproductive tracts; in the uterus, for example, pushing a baby out of the uterus and into the birth canal

Walls of structures of the urinary system, including the urinary bladder, allowing the bladder to expand so it can hold more urine, and then contract as urine is released

Walls of blood vessels, controlling the diameter of the vessels and thereby affecting blood flow and blood pressure

Walls of lymphatic vessels, squeezing the fluid called lymph through the vessels

Iris of the eyes, controlling the size of the pupils and thereby the amount of light entering the eyes

Arrector pili in the skin, raising hairs in hair follicles in the dermis

Question 25

What is cardiac muscle?

Answer 25

Cardiac muscleis found only in the wall of the heart. It is also called myocardium. As shown in the figurebelow, myocardium is enclosed within connective tissues, including the endocardium on the inside of the heart and pericardium on the outside of the heart. When cardiac muscle contracts, the heart beats and pumps blood.

Question 26

Structure of cardiac tissue

Answer 26

Like skeletal muscle, cardiac muscle is striated because itsfilaments are arranged in sarcomeres inside the muscle fibers.However, in cardiac muscle, the myofibrils are branched at irregular angles rather than arranged in parallel rows (as they are in skeletal muscle). This explains why cardiac and skeletal muscle tissues look different from one another.

The cells of cardiac muscle tissue are arranged in interconnected networks.

Question 27

The ___ is the muscle that performs the greatest amount of physical work in the course of a lifetime.

Answer 27

Heart

Question 28

What is a muscle contraction?

As well as
-Isometric
-Isotonic

Answer 28

Amuscle contractionis an increase in the tension or a decrease in the length of a muscle. Muscle tension is the force exerted by the muscle on a bone or other object. A muscle contraction isisometricif muscle tension changes, but muscle length remains the same. An example of isometric muscle contraction is holding a book in the same position. A muscle contraction isisotonicif muscle length changes, but muscle tension remains the same. An example of isotonic muscle contraction is raising a book by bending the arm at the elbow.

Question 29

NEUROMUSCULAR JUNCTION

Answer 29

The connection between a motor neuron axon terminal and a muscle fiber occurs at a site called aneuromuscular junction.This is a chemical synapse where a motor neuron transmits a signal to a muscle fiber to initiate a muscle contraction.

Question 30

Excitation-Contraction coupling

Answer 30

Although the termexcitation-contraction couplingconfuses or scares some students, it comes down to this: for a skeletal muscle fiber to contract, its membrane must first be “excited”—in other words, it must be stimulated to fire an action potential.

Question 31

What bodily disorders are muscle contractions involved in?

Answer 31

Heart failure and Strokes

Question 32

KNow this about muscle contraction (Complex)

Answer 32

A skeletal muscle contraction begins with electrochemical stimulation of a muscle fiber by a motor neuron. This occurs at a chemical synapse called a neuromuscular junction. The neurotransmitter acetylcholine diffuses across the synaptic cleft and binds to receptors on the muscle fiber. This initiates a muscle contraction.

Oncestimulated, Calcium is released from the sarcoplasmic reticulum. Calcium unshields actin and myosin cross-bridge sites. These protein filaments within the skeletal muscle fiber slide past each other to produce a contraction. The sliding filament theory is the most widely accepted explanation for how this occurs. According to this theory, thick myosin filaments repeatedly attach to and pull on thinactinfilaments, thus shortening sarcomeres.

Question 33

What is Crossbridge cycling?

Answer 33

Crossbridge cycling is a cycle of molecular events that underlies the sliding filament theory. Using energy in ATP, myosin heads repeatedly bind with and pull on actin filaments. This moves the actin filaments toward the center of a sarcomere, shortening the sarcomere and causing a muscle contraction.

Question 34

Where does ATP come from in a muscular contraction?

Answer 34

The ATP needed for a muscle contraction comes first from ATP already available in the cell, and more is generated from creatine phosphate. These sources are quickly used up. Glucose and glycogen can be broken down to form ATP and pyruvate. Pyruvate can then be used to produce ATP in aerobic respiration if oxygen is available, or it can be used in anaerobic respiration if oxygen is not available.

Question 35

What is physical exercise? (Complex)

Answer 35

Physical exercise is any bodily activity that enhances or maintains physical fitness and overall health and wellness. We generally think of physical exercise as activities that are undertaken for the main purpose of improving physical fitness and health. However, physical activities that are undertaken for other purposes may also count as physical exercise. Scrubbing a floor, raking a lawn, or playing active games with young children or a dog are all activities that can have fitness and health benefits, even though they generally are not done mainly for this purpose.

Question 36

What is physical exercise? (simple)

Answer 36

Physical exercise is any bodily activity that enhances or maintains physical fitness and overall health and wellness.

Question 37

How much physical exercise should people get?

Answer 37

In the United States, both the Centers for Disease Control and Prevention and the Surgeon General have recommended that every adult who is able should participate in moderate exercise for a minimum of 30 minutes a day. This might include walking, swimming, and/or household or yard work.

Question 38

What are the 3 types of physical exercise?

Answer 38

Physical exercise can be classified into three types, depending on the effects it has on the body: aerobic exercise, anaerobic exercise, and flexibility exercise.

Question 39

What is aerobic exercise? (complex)

Answer 39

Aerobic exercise is any physical activity in which muscles are used at well below their maximum contraction strength, but for long periods of time. Aerobic exercise uses a relatively high percentage of slow-twitch muscle fibers that consume a large amount of oxygen. The main goal of aerobic exercise is to increase cardiovascular endurance, although it can have many other benefits, including muscle toning. Examples of aerobic exercise include cycling, swimming, brisk walking, jumping rope, rowing, hiking, and tennis.

Question 40

What is anaerobic exercise?

Answer 40

Anaerobic exercise is any physical activity in which muscles are used at close to their maximum contraction strength, but for relatively short periods of time. Anaerobic exercise uses a relatively high percentage of fast-twitch muscle fibers that consume a small amount of oxygen. Goals of anaerobic exercise include building and strengthening muscles, as well as improving bone strength, balance, and coordination. Examples of anaerobic exercise include push-ups, lunges, sprinting, interval training, resistance training, and weight training (such as biceps curls with a dumbbell, as pictured below).

Question 41

What is flexibility exercise?

Answer 41

Flexibility exercise is any physical activity that stretches and lengthens muscles. Goals of flexibility exercise include increasing joint flexibility, keeping muscles limber, and improving the range of motion, all of which can reduce the risk of injury. Examples of flexibility exercise include stretching, yoga, and tai chi.

Question 42

Life gain and Exercise (Complex)

Answer 42

The U.S. Department of Health and Human Services (HHS) recommends that adults aged 18 to 64 engage in regular aerobic physical activity for 2.5 hours at moderate intensity (1.25 hours at vigorous intensity) each week. Moderate activities are those during which a person could talk but not sing. Vigorous activities are those during which a person could say only a few words without stopping for breath. When people exercise at 50 percent of the HHS guidelines, they gain an average of 1.5 years of life. Exercising at 100 percent of the HHS guidelines results in a gain of almost four years of life. The gain in life expectancy starts to level off at about 300 percent of the HHS guidelines.

Question 43

Who does exercise increase lifespan (complex)

Answer 43

developing research suggests that many of the benefits of exercise may come about because of the role of skeletal muscles as endocrine organs. Contracting muscles release hormones called myokines, which promote tissue repair and the growth of new tissue. Myokines also have anti-inflammatory effects, which, in turn, reduce the risk of developing inflammatory diseases. Exercise also reduces levels of cortisol, the adrenal cortex stress hormone that may cause many health problems — both physical and mental — at sustained high levels.

Question 44

What does physical exercise do for your cardiovascular system?

Answer 44

• Increase good cholesterol
• Reduce high blood pressure
• Reduce bad cholesterol
  -Increase insulin sensitivity
  -Increase efficiency of heart
  -Creates ability to tolerate exercise without undue stress and fatigue.

Question 45

What does physical exercise do for your brain?

Answer 45

Protect you from developing dementia

by

Increasing blood flow and oxygen availability to the brain

increasing growth factors that promote new brain cells and new neuronal pathways in the brain

increasing levels of neurotransmitters (such as serotonin), which increase memory retention, information processing, and cognition

Question 46

How does physical exercise help mental health?

Answer 46

Numerous studies suggest that regular aerobic exercise works as well as pharmaceutical antidepressants in treating mild-to-moderate depression.

Additional mental health benefits of physical exercise include reducing stress, improving body image, and promoting positive self-esteem. Conversely, there is evidence to suggest that being sedentary is associated with increased risk of anxiety.

Question 47

How does exercise help sleep?

Answer 47

A recent review of published scientific research suggests that exercise generally improves sleep for most people, and helps sleep disorders, such as insomnia. . .For sleep benefits, the optimum time to exercise may be four to eight hours before bedtime, although exercise at any time of day seems to be beneficial. The only possible exception is heavy exercise undertaken shortly before bedtime, which may actually interfere with sleep.

Question 48

Other positive effects of physical exercise:

Answer 48

Some studies suggest that physical activity may benefit the immune system. For example, moderate excise has been found to be associated with a decreased incidence of upper respiratory tract infections. Evidence from many studies has found a correlation between physical exercise and reduced death rates from cancer, specifically breast cancer and colon cancer. Physical exercise has also been shown to reduce the risk of type 2 diabetes and obesity.

Question 49

How do slow twitch and fast twitch muscles affect what you can do?

Answer 49

If you have more slow twitch muscle fibers you can do better at endurance sports than other people.

If you have more fast twitch muscle fibers you can grow bigger muscles than other people.

Question 50

Can bad stuff happen if you exercise way too much?

Answer 50

Yes
You can:
-Damage your muscles and joints
-Scar your heart and make it beat irregularly
-You can make your menstrual cycle go out of whack if you are a girl
-

Question 51

Good tips to help you exercise:

Answer 51

-Avoid an all-or-nothing point of view.
-Be kind to yourself, and reinforce positive behaviors with rewards.
-Don’t make excuses for not exercising.
-Find an activity you truly enjoy doing.
-Make yourself accountable.
-Add more physical activity to your daily life.

Question 52

___ in 5 adults will suffer from ___ pain

Answer 52

1, neck

Question 53

What are musculoskeletal disorders?

Answer 53

Injuries that occur in muscles or associated tissues (such as tendons) because of biomechanical stresses. They may be caused by sudden ecertion, over-exertion, repetitive motions, or long periods of maintaining awkward positions.

Question 54

What is a muscle strain?

Answer 54

Amuscle strainis an injury in which muscle fibers tear as a result of overstretching. A muscle strain is also commonly called a pulled muscle or torn muscle. (Strains are often confused with sprains, which are similar injuries to ligaments.) Depending on the degree of injury to muscle fibers, a muscle strain can range from mildly to extremely painful.

-Bruises
-Stiffness

Question 55

PRICE

Answer 55

Protection
Rest
Ice
Compression
Elevation

Question 56

What are NSAIDs?

Answer 56

Non-steroidal anti-inflammatory drugs

Question 57

What is tendinitis?

Answer 57

Tendinitisis inflammation of a tendon that occurs when it is over-extended or worked too hard without rest.

Question 58

What is Carpal Tunnel?

Answer 58

Carpal tunnel syndromeis a common biomechanical problem that occurs in the wrist when the median nerve becomes compressed between carpal bones

Question 59

What are Neuromuscular Disorders?

Answer 59

Neuromuscular disordersare systemic disorders that occur because of problems with the nervous control of muscle contractions, or with the muscle cells themselves. These disorders are often due to faulty genes and not due to biomechanical stresses.

Question 60

What is Muscular Dystrophy?

Answer 60

Muscular Dystrophy

Muscular dystrophyis a genetic disorder caused by defective proteins in muscle cells. It is characterized by progressive skeletal muscle weakness and death of muscle cells and tissues. Muscles become increasingly unable to contract in response to nervous stimulation.

Question 61

What is DMD?

Answer 61

Duchenne muscular dystrophy (DMD) is a progressive weakening of the skeletal muscles. It is one of several diseases collectively referred to as “muscular dystrophy.” DMD is caused by a lack of the protein dystrophin, which helps the thin filaments of myofibrils bind to the sarcolemma. Without sufficient dystrophin, muscle contractions cause the sarcolemma to tear, causing an influx of Ca++, leading to cellular damage and muscle fiber degradation. Over time, as muscle damage accumulates, muscle mass is lost, and greater functional impairments develop.

Question 62

What is Myasthenia Gravis?

Answer 62

Myasthenia gravis is an autoimmune disorder in which circulating antibodies block the nicotinic acetylcholine receptors on the motor end plate of the neuromuscular junction. This blockage of acetylcholine receptors causes muscle weakness, often first exhibiting drooping eyelids and expanding to include overall muscle weakness and fatigue.

Question 63

What is Parkinson’s disease?

Answer 63

Parkinson’s diseaseis a degenerative disorder of the central nervous system that mainly affects the muscular system and movement. Four motor signs and symptoms are considered defining in Parkinson’s disease: muscle tremor (shaking), muscle rigidity, slowness of movement, and postural instability

Question 64

Difference between Primary and Secondary Parkinsons?

Answer 64

Primary - disease sets in in old age with no apparent cause

Secondary - disease sets in after exposure to harmful chemicals or repeated head injury.