anatomy and Physiology I chapter 9 (text/assesment questions + prelab/lab

Match the following skeletal muscle functions with their definitions.

movement=created by contracting and pulling on tendons support visceral organs and shield tissue from injury=supporting structure contract to hold the body still=posture speak¸ type¸ write¸ facial expressions¸ and gestures=communication

Sort the steps in the sliding filament theory in order of occurrence.

-crossbridge -power stroke -dissociate -reactivate

Select the biceps femoris

center muscle

Which of the following is not a distal attachment site for trapezius? Clavicle Acromial process of the scapula Spine of the scapula Intertubecular groove of the humerus

intertubecular groove of the humerus

Smooth muscles are responsible for which of the following functions? involuntary movements like regulation of blood flow through vital organs voluntarily contracting to digest food coordinating actions and transmitting signals to and from different parts of its body permitting blood to circulate and transport nutrients

involuntary movements like regulation of blood flow through vital organs

Which of the following muscle fiber types would be recruited for sitting? type I type IIA type IIB type III

type I

The primary functions of skeletal muscle include which of the following? Select all that apply. create movement by contracting and pulling on tendons communicate by speaking¸ writing¸ and making facial expressions coordinate actions and transmit signals to and from different parts of its body support organs and shield tissue from injury

-create movement by contracting and pulling on tendons -support organs and shield tissue from injury

A cross-bridge forms when which of the following occurs? Select all that apply. The myosin heads bind to the attachment sites on the actin myofilament. G-actin polymerizes to F-actin. Actin and myosin bind to form a physical link. The muscle returns back to its original position after passive or active elongation.

-the myosin heads bind to the attachment sites on the actin myofilament -actin and myosin bind to form a physical link

exactly whats on practical exam picture and muscular terms of the Muscles of the Upper Arm

Biceps brachii-supinates forearm, flexes the elbow Triceps brachii-elbow extension

Once an action potential excites the sarcolemma, a series of actions take place in order to produce a muscle contraction. This process primarily includes which of the following ions? Ca2+ ATP K Na

Ca2+

What molecule is responsible for the coupling of excitation of the fiber membrane to the muscle contraction? oxygen potassium sodium Ca^2+

Ca^2+

Muscle Metabolism in Contracting Muscle

The demand for ATP during a muscle contraction is very high, and the skeletal muscle is unable to store the high volumes of ATP that are needed for contraction. Instead, resting muscles only have enough ATP to begin a muscle contraction, and ATP must be synthesized as contraction occurs. Throughout the remainder of the muscle contraction, ATP will continue to be generated at about the same rate that it is used.

What is the action of the muscle at the tip of the arrow in the image? ​ Adduction, flexion, and medial rotation of the arm Abduction, flexion, and medial rotation of the arm Adduction, extension, and medial rotation of the arm Adduction, flexion, and lateral rotation of the arm

abduction, flexion, and medial rotation of the arm

The primary muscles that work together to bring about a movement are called ______. agonist antagonist origin insertion

agonist

most smooth muscles are single-unit functioning, meaning that either the whole muscle ______ or the whole muscle ______ stretches; lengthens activates; deactivates circulates; distributes contracts; relaxes

contracts; relaxes

What forms of energy reserves do resting skeletal muscle fibers contain? glycogen creatine Phosphate ATP calcium

creatine Phosphate

List the following phases of the stretch-shortening-cycle in the correct order. eccentric phase concentric phase amortization phase

eccentric phase amortization phase concentric phase

which of the following muscles will allow you to both flex your knee and plantar flex your foot Soleus Gastrocnemius Tibialis anterior Biceps femoris

gastrocnemius

This man is "winking" in the image. Which muscle is most likely involved in this action? ​ Orbicularis oculi Orbicularis oris Temporalis Occipitofrontalis

orbicularis oculi

Click on orbicularis oris.

the lips

Select the muscle that allows you to abduct the arm at the shoulder joint. ​

the one under clavicle

Which muscles allow for the action at the tip of the pointer in the image? Gasctrocnemius Soleus Tibialis anterior Semimembranous Biceps femoris

- gastrocnemius - soleus

The muscle in the picture whose innervation is through the accessory nerve and when contracted allows you to flex your neck has its origin(s) where? Mastoid process of the temporal bone Clavicle Sternum

- mastoid process of the temporal bone - sternum

Which of the following muscles would be needed to take a bite out of a piece of pizza? Sternocleidomastoid Masseter Temporalis Orbicularis oculi Occipitofrontalis

- masseter - temporalis - orbicularis oculi

Describe the muscles and the actions needed to climb a flight of stairs.

The quadriceps, gluteus maximus, hamstrings, gastrocnemius, and soleus muscles are among the muscles required. In order to extend the leg and bend the thigh as you place your foot on the subsequent step, you would need to use your quadriceps. As you ascend toward the step, you will need to extend your leg and thigh using your hamstring and gluteus maximus muscles. When you travel upward, the soleus and gastrocnemius muscles will be required to plantar flex the foot of the other leg. As you continue to climb the stairs, you'll alternate between using your quadriceps on your anterior thigh and your gluteus maximus and hamstrings on your posterior thigh.

Why is there a smaller muscle fiber to motor neuron ratio for muscles responsible for precision?

because control of the individual muscle fibers increases. specifically, with a smaller number of muscle fibers per motor unit, a person's ability to control the amount of force exerted increases, making the movement more precise

When a person stands up out of a chair, the agonist muscles involved include the quadriceps, gluteals, and hamstrings, which are contracting in which type of muscle action? Select all that apply. isotonic isometric concentric eccentric

isotonic concentric

Which muscle is contracting to allow someone to touch their toes as shown in the picture? Rectus abdominus Biceps brachii Latissimus dorsi Pectoralis major

latissimus dorsi

which of the following muscles is the "kissing" muscle Temporalis Orbicularis oris Sternocleidomastoid Occipitofrontalis

orbicularis oris

Smooth muscle can maintain optimal force at a range of lengths due to which of the following characteristics? plasticity elasticity reversibility extensibility

plasticity

Match the training principle with its appropriate description.

progressive overload=A person gradually increases the stress on a muscle¸ and the muscle adapts to the imposed stress level. principle of specificity=The human body makes specific adaptations to imposed demands. principle of reversibility=A person stops training or reduces their training¸ and there is a loss in adaptation brought on by the training.

Which of the following cells are spindle-shaped and have a single, centrally located nucleus? skeletal muscle cells cardiac muscle cells smooth muscle cells brain cells

smooth muscle cells

Exercise is a side-effect-free activity available to most people in some way. Is there a need for an exercise pill?

some people cant exercise so the exercise pill will outweigh those cases.

Select the sartorius.

the point at top left

Which of the following muscle fiber types would be recruited for jumping on a trampoline? Select all that apply. type I type IIA type IIB type III

type I type IIA type IIB

Click on the actin.

little bubble

Design an experiment to assess the effects of aging on the skeletal muscle system.

A muscle biopsy may reveal information about muscle fiber composition (e.g., fast twitch vs. slow twitch), as well as hypertrophy and atrophy (these may also be visible in gross anatomy). Functional testing could be used to examine the length tension relationship or the ability to generate force. Blood tests could be used to look at metabolic byproducts (e.g. creatinine).

The time of a murder victim's death is commonly estimated by the flexibility of the body due to a lack of ________. Ca^2+ ATP sodium oxygen

ATP

Energy Consumption in Skeletal Muscle

As you learn about the different metabolic systems or processes by which the muscles consume energy to create movement, it is important to connect this concept of metabolism to the ideas that are commonly used in everyday talk of body weight loss and weight maintenance. You have likely heard people express that they are trying to increase their metabolism for weight loss purposes. In the next sections, you will learn that metabolism, or the rate at which people consume kilocalories (commonly referred to as "burning calories") is most directly related to skeletal muscle activity and degree of muscle tone. The higher the intensity of the activity one engages in, the higher the rate at which one consumes kilocalories. Additionally, the more muscle tone a person has, the higher their metabolism is continuously (even at rest) because their musculature maintains a greater number of cross-bridges, which requires ATP.

Prime Mover/Antagonist

Flexion of the vertebral column= Abduction of the arm= Flexion of the elbow= Flexion of the femur= Flexion of the knee=

What happens in the skeletal muscle when lactic acid is produced during high intensity activity? Sort the following sequence of events from first to last.

Lactic acid accumulation causes an increase in acidity. Muscular fatigue ensues. When exertion levels are still high¸lactic acid is converted to pyruvic acid in the liver. Eventually muscular activity decreases as a result of fatigue. When more oxygen is available¸lactic acid is reused in the muscle as energy.

Microanatomy of Skeletal Muscle

Muscle cells and other cells share similar structures, but because muscle is highly specialized, muscle cells have their own nomenclature. For example, sarcoplasm is the cytoplasm of a muscle cell, and the sarcoplasmic reticulum is equivalent to the endoplasmic reticulum. Some components of skeletal muscle tissue are also unique, such as myofibrils. Morphologically, muscle fibers (muscle cells) are cylindrical cells that are about the diameter of a human hair (10-100 μm) and are very long (e.g., up 23 inches in the sartorius muscle). These unique characteristics are acquired during development, or myogenesis. During myogenesis, myoblasts fuse to form myocytes. This explains why muscle fibers can be so long—they are formed from the fusion of many precursor cells during development. The length of a muscle fiber may run the entire length of the muscle, but this is rare. More commonly, muscle fibers are oblique to the muscle's axis of force. Some myoblasts do not fuse with the developing muscle and remain in the adult skeletal muscle tissue as satellite cells. Satellite cells have regenerative properties and are therefore important in the growth and repair of the muscle fibers. ​The picture of a skeletal muscle myocyte shows that it looks very different from many of the cells we have discussed previously. Figure 9.4 provides an illustration of the interior structure of a skeletal muscle fiber. The sarcolemma is contiguous with the endomysium and surrounds the sarcoplasm. The sarcoplasm contains myofibrils, which are bundles of contractile proteins. The two major contractile proteins are actin and myosin myofilaments. Actin and myosin are arranged longitudinally along the myofibril in repeating units called sarcomeres, which are the smallest contractile units of skeletal muscle. At both ends of the skeletal muscle fiber, the myofibrils are anchored to the sarcolemma, which is attached to the tendons. Therefore, when myofibrils contract, the entire cell shortens; this pulls on the tendon, which pulls on the bone and creates movement. Actin is a thin filament that looks similar to a tiny strand of pearls twisted together. Other proteins that form the thin filament are nebulin, tropomyosin, and troponin, which are discussed later in the chapter. Myosin filaments are thick filaments and look like double-headed golf clubs (Figure 9.5). Actin comes in different forms: filamentous actin, or F-actin, which initiates many cellular processes including cell motility and muscle contraction; and G-actin (globular actin), which is the monomer from which F-actin is produced. F-actin is assembled from the polymerization of G-actin, forming a twisted strand of many G-actin molecules. Additionally, a long strand of nebulin spirals along the F-actin, holding the F-actin strands together. Importantly, each molecule of G-actin contains a binding site for myosin filaments. The myosin heads, which look like the head of a golf club, bind to actin to form a cross-bridge. This binding is calcium-dependent (and is covered in more detail later in the chapter). Other proteins found within connective tissue are called elastic fibers, which can stretch up to 1.5 times their length and then recoil to their resting length. Examples of elastic fibers include elastin, elaunin, and oxytalan. Collectively, elastic fibers give muscle the property of elasticity, which means that muscles will resist elongation (lengthening) and will recoil back to their original position after passive or active elongation. Much like a spring! Sarcomeres, when viewed under a microscope, have an alternating light and dark striated appearance (Figure 9.6). Figure 9.7 shows a schematic of how the following structures are arranged within a myofibril. The light stripe is the I-band (for isotropic, named for the way I-bands look under a polarizing microscope) consists only of actin. The microfilament α-actinin is responsible for attaching actin to the Z-disk (German for "in-between" discs), which forms the left and right boundaries of each sarcomere. The dark stripe is the A-band (for anisotropic), which extends through the entire length of myosin and contains overlapping proteins. The H-zone (German for lighter appearance) is a second light zone located in the center of each sarcomere and only has myosin. The M-line (containing the protein myomesin), located in the center of the sarcomere, is connected to the Z-line by titin. During a muscle contraction, the H-zone and I-band shorten in length as the Z-lines pull toward the M-line. Because all sarcomeres are interconnected within a myofibril, this causes the entire muscle fiber to shorten. Later in the chapter, we will discuss the mechanics of filament sliding in greater detail.

Develop a proposal that would persuade a retirement home to hire an exercise leader to train the older adults.

Muscle anatomy and micro anatomy change as we age. Exercising keeps muscles active even as they age, and it helps to increase muscle fiber size, muscle tone, and so on. It is also beneficial to cardiovascular health.

Explain a model that explains the process by which muscular fatigue occurs.

Muscle fatigue is complicated and poorly understood, but it can be caused by changes in calcium handling within the muscle during excitation contraction coupling known as "calcium theory" or by a lack of available ATP and nutrients within the muscle known as "depletion theory"

The contraction of a skeletal muscle exerts a pull on a bone because which of the following is true? Muscles are attached directly to bones. Muscles are attached to bones by cartilage. Muscles are attached to bones by tendons.

Muscles are attached to bones by tendons.

exactly whats on practical exam picture and muscular terms of the Muscles of the Legs

Quadriceps-extends the knee (rectus femoris, vastus muscle (medialis, intermedius, lateralis) Hamstrings-thigh extension at hip joint, knee flexion at hip joint (bicep femoris, semimembranosus, semitendinosus) Gastrocnemius-plantar flexion, flex leg at knee joint Soleus-plantar flexion at ankle joint

Match the muscle with its correct action.

Sartorius=Laterally rotates the thigh and flexes the leg Flexes thigh and extends the leg=Rectus femoris Adducts the thigh and flexes the leg=Gracilis Adducts and medially rotates the thigh=Adductor longus

Tissue

Skin Fat Muscle Tendon Ligament Cartilage Blood Vessels Nerves

Match the muscle of the rotator cuff with its action.

Supraspinatus-Abducts arm Laterally rotates arm-Infraspinatus Laterally rotates arm-Teres minor Medially rotates arm-Subscapularis

The Neuromuscular System of Skeletal Muscle

The Motor Unit Neurons directly innervate skeletal muscle through the epimysium. This is essential because, as an excitable tissue, skeletal muscle requires stimulation in order to contract. Synapses between neurons and skeletal muscles are rarely 1:1. The term motor unit describes one alpha motor neuron and all the muscle fibers it innervates (Figure 9.9). Motor units can vary in size from a single muscle fiber to several hundred. In general, muscles that are responsible for very precise movements have fewer fibers per motor unit. In contrast, muscles that have hundreds of fibers per motor unit generally perform tasks that require greater amounts of force, like walking or jumping with the use of the quadriceps, gluteals, and hamstrings (i.e., muscles in the legs). The process by which a muscle is activated begins when the motor cortex in the brain sends a nerve impulse, which travels through the spinal cord to the alpha motor neuron. This stimulates the muscle action potential, depolarizes the sarcolemma, and causes the sarcomeres to slide. All fibers in a single motor unit contract in unison. The Neuromuscular Junction ​The neuromuscular junction (NMJ) is a chemical synapse formed between an alphamotor neuron and a muscle fiber (Figure 9.10). Specifically, it is where the axon terminal of the alpha motor neuron and the membrane of the muscle fiber, or motor endplate, meet. The NMJ consists of a presynaptic neuronal membrane that contains vesicles filled with the neurotransmitter acetylcholine (ACh), juxtaposed with the muscle sarcolemma which expresses nicotinic acetylcholine receptors. Before reading on, refer to Chapter 8: Excitable Cells to revisit the process by which neurons are excited and neurotransmitters are released at the synapse; there are many similarities between neuronal synapses and synapses between neurons and muscle. Alpha motor neurons release the neurotransmitter acetylcholine (ACh), which diffuses across the synaptic cleft and binds to nicotinic acetylcholine receptors on the motor endplate of the muscle fiber. This stimulation continues until acetylcholinesterase degrades acetylcholine in the synaptic cleft. End Plate Potentials in Skeletal Muscle After it is released from presynaptic vesicles, ACh diffuses across the synaptic cleft and binds to ACh receptors on the motor endplate. Nicotinic ACh receptors are ligand-gated cation channels that allow extracellular Na+Na+to enter the muscle fiber and intracellular K+K+to exit. The simultaneous increase in intracellular Na+Na+and decrease in K+K+causes the membrane potential to depolarize. This produces a graded potential called an end plate potential, which is similar to the synaptic potential produced in the dendrites of neurons. Like the graded potential in neurons, the endplate potential triggers an action potential in the muscle, which propagates along the sarcolemma just as an action potential would propagate along the axon of a neuron (Chapter 8: Excitable Cells). The action potential triggers the release of Ca2+Ca2+into the sarcoplasm via the sarcoplasmic reticulum, which then triggers muscle contraction. This process of converting the action potential into a calcium signal is known as excitation-contraction coupling (ECC) and is reviewed in depth later in this chapter. Tension Development in Skeletal Muscle You might be wondering—if there is no variation in the intensity of an action potential, how can you control how much force you apply when picking up a heavy bag versus a feather? How is this variance in force output regulated? Both of these questions can be answered by thinking about the relationship between neurons and muscle fibers, and more specifically, the frequency of muscle stimulation and the number of motor units activated. 9.2.4.D-1 Frequency of Muscle Stimulation A muscle twitch is a single contraction and relaxation cycle within a muscle fiber and consists of three phases (Figure 9.12). In the latent phase, the action potential depolarizes the sarcolemma and the sarcoplasmic reticulum releases Ca2+Ca2+. The muscle does not produce tension during this period because the cross-bridge cycle has not yet begun. In the contraction phase, tension in the muscle fiber peaks. As tension increases, cross-bridge interactions occur because Ca2+Ca2+exposes binding sites on the actin filaments. During the relaxation phase, Ca2+Ca2+levels decrease, which causes the binding sites on the actin filaments to be covered and the number of active cross-bridges to decline. A single stimulation of the muscle fiber produces a single twitch of that fiber; this may be as brief as 7 milliseconds. Therefore, a single muscle twitch does not accomplish anything useful in terms of movement. In order for a muscle contraction to last longer than a twitch, subsequent muscle twitches must occur before the relaxation phase has ended. The addition of one twitch to another is called wave summation. A more powerful muscle contraction occurs with wave summation because stimulation continues and the muscle is never allowed to relax completely; as a result, tension rises and peaks. This produces a tetanic contraction (also called tetanus, but different from the disease tetanus), which is a sustained muscle contraction caused by a motor neuron firing action potentials at a very high rate. A tetanic contraction can either be fused (complete) or unfused (incomplete) (Figure 9.13). Unfused tetanus occurs when the muscle fibers only partially relax before the next stimulus because they are being stimulated at a high frequency. Fused tetanus occurs with a very high rate of stimulation and relaxation does not occur. This occurs because the high Ca2+Ca2+concentration in the sarcoplasm prolongs the contraction. Nearly all "normal" muscle contractions involve complete tetanus of the activated muscle fibers Earlier in the chapter, we learned that if a person decides to pick up a feather, the brain sends a message only to the motor units required to pick up that feather, which would be very few. If it wants to pick up something heavier, it must contract more muscle fibers by stimulating more motor units. This process is called muscle fiber recruitment (Figure 9.14).. The more muscle fibers within a muscle that are recruited, the greater the tension produced by that muscle. For example, if someone were to pick up a fifty-pound bag, they would need to recruit a large number of motor units in order to recruit more muscle fibers and create more force. If this person recruited the same number of muscle fibers to pick up a teacup as they did to pick up that fifty-pound bag, they would hit themselves in the face with the teacup, because the force is greater than what is needed for that movement.

What advantage would there be in having a muscle in which the fibers were organized in different ways?

This allows muscles to carry out different types of movements that vary in strength, speed, endurance.

An activity that would require anaerobic activity would be which of the following? sitting watching TV going on a light walk a 100-meter dash brushing teeth

a 100-meter dash

From a neurological perspective, in order to produce more force, which of the following must occur? more ATP is needed a greater number of motor units must be activated more strength is required progressive overload must be achieved

a greater number of motor units must be activated

Match the step of the sliding filament model to its correct description.

a physical link between actin and myosin head=cross-bridge after myosin and actin form a cross-bridge¸Pi disassociates and the fiber shortens=power stroke another ATP attaches to myosin and the myosin and actin attachment weakens and detaches=disassociate the myosin head is reactivated when ATP is hydrolyzed to ADP and inorganic phosphate=reactivate

Which of the following is NOT a function of skeletal muscle? maintains posture regulates temperature circulates blood through the body creates bodily movement

circulates blood through the body

Click on the fasciculus.

layer outside

Which of the following causes muscle soreness? lack of fitness lactic acid microtrauma to the sarcomere occurs and activates pain receptors insufficient stretching pre- and post-exercise

microtrauma to the sarcomere occurs and activates pain receptors

The optimal length for force production of the sarcomere in the skeletal muscle is which of the following? any length is optimal due to plasticity moderate (80-120% of resting sarcomere length) stretched (120-150% of resting sarcomere length) short (60-70% of resting sarcomere length)

moderate (80-120% of resting sarcomere length)

Which of the following is NOT an effect of aging on the muscular system? atrophy of type II fibers sarcopenia strength and power decline muscle fibers become shorter

muscle fibers become shorter

If a motor unit contained 1500 muscle fibers, what type of movements would this muscle likely be responsible for? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. fine motor delicate movements powerful movements

powerful movements

which of the following muscles will allow you to bend over and touch your toes Pectoralis major External intercostals Internal intercostals Rectus abdominis

rectus abdominis

Which of the following muscles allows you to medially rotate your arm? Deltoid Subscapularis Teres minor Supraspinatus

subscapularis

The disassociation of the myosin cross-bridge is directly activated by which of the following? the attachment of ATP to myosin heads the hydrolysis of ATP repolarization of the T-tubules Ca is shuttled back out of the cell

the attachment of ATP to myosin heads

To allow for cross-bridge interactions during muscular contraction, Ca must bind with which of the following? troponin tropomyosin actin myosin

troponin

Do you think that people with different muscle fiber types (type I versus type II) prefer different exercise modes and intensities?

type i with fast twitched fibers prefer more shorter, higher intensity workout. People with slow twitched fibers prefer long endurance workouts.

case study: Myasthenia gravis

Myasthenia gravis is an autoimmune disorder and common neuromuscular disease that produces varying degrees of muscle weakness. This disease results from antibodies that block or damage nicotinic acetylcholine receptors at the NMJ. Therefore, it is generally treated with medications that inhibit acetylcholinesterase.

Smooth muscle can hold an involuntary contraction for long periods of time; some smooth muscles are in nearly a constant state of contraction. Which of the following is an example of an involuntary smooth muscle contraction that humans are consciously aware of? bladder collecting urine before disposal via urination heart contracting to pump blood to the extremities uterine contractions during child birth biceps contracting to pick up a pencil

heart contracting to pump blood to the extremities

Which group of muscles does this baseball pitcher use to throw the ball? ​ Rotator cuff muscles Hamstring muscles Quadricep muscles Biceps muscles

rotator cuff muscles

appendicular and axial muscles

Like the skeleton, the skeletal muscles can also be divided into axial and appendicular categories. The axial muscles have attachments located only on the axial skeleton and structures associated with the axial skeleton. Axial muscles are responsible for a number of actions including: moving the head, neck, and back, moving the face for facial expressions, chewing and swallowing, moving the eyes, breathing, and supporting abdominal and pelvic organs. Axial muscles do not move the upper or lower limbs. Instead, the muscles that move the pectoral girdle, pelvic girdle, and limbs are classified as appendicular muscles. There are over 600 muscles found throughout the human body. This lab will cover only a handful of these muscles. For each muscle discussed in the lab we will look at the: location, origin, insertion, function, and innervation of the muscle.

Muscles of the Head and Neck

Occipitofrontalis-moves forward (our forehead and eyebrows) and draws back scalp Orbicularis oculi-tightly close the (eye during winking) Orbicularis oris- sphincter "circular muscular opening" of the (mouth and closes the lips). The masseter-The muscles of mastication (chewing). Responsible for elevating the mandible to close the jaws (as in biting) zygomaticus-pull corners of the mouth (smiling muscle) sternocleidomastoid-primary muscles which moves the (head and neck). Neck flexion, bending of the neck, contralateral rotation of the head

exactly whats on practical exam picture and muscular terms of the Muscles of the Abdomen

Rectus abdominis-flexes vertebral column External obliques-flex vertebral column: rotate trunk and bend it laterally Internal obliques-flex vertebral column: rotate trunk and bend it laterally

Select the long head of triceps brachii.

bottom muslce

Which of the following is the primary flexor of the forearm? Biceps brachii Brachialis Brachioradialis Triceps brachii

brachialis

With this example and muscle color types in mind, what parts of a chicken are fast-twitch and which parts are slow-twitch?

breast=fast-twitch leg/neck=slow-twitch

Muscle fibers in a skeletal muscle form bundles called ______. fascicles myofibrils sarcomeres endomysium

fascicles

Match the following levers with their definitions and examples:

first-class lever (definition)=a lever for which the muscle force and resistive force act on opposite sides of the fulcrum first-class lever (example)=neck and elbow second-class lever (definition)=a lever for which the muscle force and resistive force act on the same side of the fulcrum¸ with the muscle force acting through a moment arm longer than that through which the resistive force acts second-class lever (example)=calf muscle (gastrocnemius) at the ankle joint third-class lever (definition)=a lever for which the muscle force and resistive force act on the same side of the fulcrum¸ with the muscle force acting through a moment arm shorter than that through which the resistive force acts third-class lever (example)=elbow flexion with a bicep curl

At what age does sarcopenia generally begin? after 50 years of age in one's 20s between 15-20 years of age post menopause

in one's 20s

When an action potential moves down an excitable membrane, this process is called ______. propagation the wave spreading transference

propagation

Match the muscle fiber characteristics with the correct type of muscle fiber:

red in color=type I endurance=type I intermediate force production=type IIA fast contraction speed=type IIA white in color-type IIB large in size=type IIB

Select the long head of biceps brachii. ​

the long one at right top

Which of the following muscles is considered a muscle of mastication? Masseter Orbicularis oculi Occipitofrontalis Sternocleidomastoid

Masseter

Aging

Not only has life expectancy increased drastically in the last century, from 47 to 78 years of age, but many older adults are also able to pursue an active and fulfilling life well into their later years. Studies of world records indicate that athletic peak performance occurs in one's late 20s (depending on the sport) and is maintained for only about five years before a decline in performance occurs. This decline occurs in everyone, not just elite athletes, and results from the effect of aging on skeletal muscle. The various effects of aging on the muscular system are as follows: ​Skeletal muscle fibers become thinner. Muscle mass can be estimated using measurement tools, such as an ultrasound, that take an image of the cross-section of a muscle. Research has shown that substantial losses of both muscle fiber size and number of muscle fibers occurs as one ages. This condition is called sarcopenia, an age-related loss of skeletal muscle mass and strength. In some musculature, muscle fibers become replaced by fat and connective tissue. The substitution for contractile tissue helps explain why force output per cross-sectional unit is significantly lower in some older adults when compared with younger adults. Furthermore, adults who are in their 80s have about half the number of muscle fibers of young adults. This loss in muscle fibers begins in the third decade of life for both men and women. Research has also shown that, independent of increases in fat cells and connective tissues in skeletal muscle, the cross-sectional mass of the muscle decreases by 40% in men and 32% in women between the 3rd and 9th decades of life. The decrease in muscle mass is largely due to a selective loss of type II muscle fibers (refer to Chapter 10: Muscle Mechanics for more on fiber types) and a decreased ability of the motor unit to recruit type II muscle fibers. Muscular strength declines. Because the musculature contains smaller fibers and a smaller number of fibers as we age, the muscle also contains fewer ATP, creation phosphate, and glycogen reserves. The overall effect is a reduction in the amount of muscular strength, endurance, and a tendency to fatigue more quickly. Cardiovascular output also decreases with age. Therefore, when blood flow to the active muscle does not increase with exertion as quickly as it does in younger people, these muscular and cardiovascular effects combine to produce a 30-50% decline in aerobic and anaerobic performance by the age 65. Skeletal muscle becomes less flexible. Flexibility (elasticity) is the ability of the muscle to move through its full range of motion. As skeletal muscles age, they develop fibrous connective tissue, a process called fibrosis. Fibrosis restricts movement and circulation. When the musculature is inflexible, it often leads to poor posture, the joints have a decreased range of motion, and the body is more likely to become injured. Flexibility can be maintained and improved through static stretching and resistance training through a full range of motion. Tolerance for exercise decreases. A lower tolerance for exercise results from a decrease in the body's ability to thermoregulate and an increase in the tendency to fatigue quickly. Adults over 65 cannot release heat as effectively as younger people, and as a result, they are more likely to become overheated. Ability to recover from muscular injuries decreases. The number of satellite cells decreases and the number of fibrous tissue increases with age. These effects combine to prevent repair of injured tissue, often resulting in scar tissue.​

The Length-Tension Relationship

The amount of strength your muscles are able to produce varies by the joint angle in which you are positioned. This concept is called the length-tension relationship of skeletal muscle, which describes the link between resting muscle length and tension generation (Figure 9.16). When the length of the sarcomere is too short or too long, actin and myosin cannot optimally produce cross-bridges, which reduces the efficiency of filament sliding. At its longest length, it is difficult for the actin and myosin to reach each other to make cross-bridges. At its shortest length, the Z-lines "crumple up" the myosin heads so that they cannot create cross-bridges with actin. Therefore, the greatest amount of tension occurs when actin and myosin overlap at a moderate level (which occurs at about 80-120% of resting sarcomere length).

Muscle Metabolism 9.3.1.A Muscle Metabolism in Resting Muscle

When the muscles are at rest (e.g., when you are sitting or lying down), more ATP is produced than is needed; in this scenario, ATP transfers this excess energy to creatine. Creatine is a naturally occurring molecule in the body that helps supply energy to the muscle cells. When ATP transfers its energy to creatine, this creates a high-energy compound called creatine phosphate (CP): ATP+creatine⟶ ADP+creatinephosphateATP+creatine⟶ADP+creatinephosphate During a skeletal muscle contraction, when the thick myosin filaments form a cross-bridge, they hydrolyze ATP to produce ADP (adenosine diphosphate) and inorganic phosphate. The reverse reaction is then set in action to convert ADP back to ATP: ADP+creatinephosphate⟶ ATP+creatineADP+creatinephosphate⟶ATP+creatine At rest, skeletal muscle fibers store about six times more creatine phosphate than ATP. When a muscle begins to contract, it uses up these extra energy stores in about 15 seconds. The muscle must then use other metabolic processes to convert ADP to ATP, such as aerobic metabolism or glycolysis.

Discuss the different movements achieved when you contract the rectus abdominus together with the external oblique muscles versus just contracting the external oblique muscles on the left vs. right side of your body.

You can stoop and touch your toes by tensing all three muscles at once. The spinal column is flexing in this manner. The torso will be pulled to the left or right by tightening the oblique muscles on either the left or right side, respectively.

So, how do chickens behave? Do they fly south for the winter like most birds?

chickens cant fly as it will be a lengthy flight instead they walk around all day moving their head back and forth.

When strength is lost as a result of inactivity, the two primary factors responsible for this effect include ______. decreased muscle fiber/motor unit recruitment and muscle atrophy hyperplasia and hypertrophy decreased cross-sectional area of the type I fibers the all-or-nothing principle and atrophy of type I fibers

decreased muscle fiber/motor unit recruitment and muscle atrophy

What barriers do scientists face when doing research on human skeletal muscle?

scientists are limited in their research of human subjects, primarily by ethics. despite the dire need to learn more about skeletal muscle, it is not ethical to cut open a living human muscle to learn about how it contracts. of course, cutting open a person's muscles would cause pain and injury to them. occasionally, the benefits of the research to society may outweigh the potential pain and injury to an individual person (if the benefits are large and the costs are small). for example, a scientist may perform a muscle biopsy on a live human to test a treatment to a muscular disease. since muscle biopsies are painful, another barrier scientists face are finding people who will participate in such studies

Skeletal Muscle Movement

Skeletal muscle is an excellent example of how structure at the molecular scale affects function at the macro scale. Skeletal muscles are most often associated with movement, but how is a movement actually produced? Muscles do not exert force directly on the ground, external objects, or against gravity. Instead, muscles create movement by pulling on the bones, similar to the way strings pull the arms and legs of a puppet (Figure 9.2). As muscles pull on bones, they create movement of the joints, which in turn creates movement of the body. Contrary to the popular belief that muscles both push and pull on bones, in reality, muscles only pull. This may sound puzzling because our bodies can make a number of pushing movements (a push-up, for example). But even the body's ability to push objects away from itself is created by muscles pulling on bones. In the case of a push-up, the pectoralis, deltoid, and triceps muscles produce the necessary pull.

Excitation-Contraction Coupling in Skeletal Muscle

The sequence of events that converts action potentials in a muscle fiber to a contraction is called excitation-contraction coupling. The action potential travels across the sarcolemma of a muscle fiber to affect the entire excitable membrane, through a process referred to as action potential propagation. Let's take a closer look at excitation-contraction coupling, which begins when an action potential travels down the motor neuron and induces the release of acetylcholine (ACh) from the presynaptic nerve terminal (Figure 9.17). ACh then diffuses across the synaptic cleft and binds to nicotinic acetylcholine receptors (AChR)—which are ligand-gated cation channels—on the muscle cell membrane. Opening of the AChR allows Na+Na+and K+K+to move down their concentration gradients. However, Na+Na+influx predominates because resting membrane potential is much closer to the equilibrium potential for K+K+ than it is for Na+Na+, resulting in a net inward Na+Na+current (INaINa​)-mediated graded potential known as an end-plate potential (EPP). The inward INaINa​ spreads passively and depolarizes the muscle cell membrane past threshold, inducing the opening of voltage-gated Na+Na+channels in the muscle cell. Typically, there is enough ACh released at the neuromuscular junction to drive membrane potential past threshold. ​The voltage-gated Na+Na+channels in the muscle cell membrane initiate a wave of depolarization that travels over the cell membrane. The depolarization of the muscle cell membrane depolarizes the T-tubule membrane, which carries the depolarization current deep into the muscle fiber. Where the sarcoplasmic reticulum connects to the T-tubules, the sarcoplasmic reticulum forms sack-like bulges called terminal cisternae. Two terminal cisternae and one T-tubule comprise what is called a triad of membranes (Figure 9.18). The triad includes the sarcoplasmic reticulum on two sides with the T-tubule sandwiched in between. The membranes of the T-tubules and the terminal cisternae are linked by proteins that are responsible for mediating Ca2+Ca2+release: the ryanodine receptor (RyR) and the dihydropyridine receptor (DHR). Specifically, depolarization of the T-tubules causes the opening dihydropyridine (DHP) L-type voltage-gated Ca2+Ca2+channels, which are connected via scaffolding proteins to the RyR channels on the sarcoplasmic reticulum membrane. This, in turn, causes RyR channels to open, and Ca2+Ca2+is released onto the thick and thin filaments in the sarcoplasm (i.e., the cytoplasm of the muscle fiber). The sarcoplasmic reticulum has 2,000 times more Ca2+Ca2+than the sarcoplasm. This rapid influx of Ca2+Ca2+is what initiates muscle contraction. Therefore, Ca2+Ca2+is responsible for coupling excitation of the muscle fiber membrane to the muscle contraction.

Muscle Fatigue

A muscle has become fatigued when it cannot continue muscular contractions at the same rate despite nervous system stimulation. A variety of situations may cause muscle fatigue, all of which differ depending on the intensity of muscular activity. After high-intensity exercise like sprinting a 100-meter dash, the skeletal muscle depletes the ATP and creatine phosphate stores and lactic acid begins to build up. Exhaustion of energy stores paired with an increase in acidity from lactic acid buildup creates muscular fatigue. Another example of fatigue includes activity at a moderate intensity over a long period of time, like running a marathon. ATP demands can keep up through aerobic metabolism over the course of a few hours during an endurance event like this, but if the runner does not pace herself appropriately, she may deplete all of her glycogen (carbohydrate) stores and fatigue will occur. This means that her body will not have enough energy (ATP) to continue running at the same rate, and she will have to slow down. In order for a muscle to function normally, certain conditions must be fulfilled. It must have substantial energy reserves, a normal circulatory supply, and a normal blood oxygen concentration. Situations that interfere with these requirements lead to premature muscle fatigue. Examples include tight clothing resulting in reduced blood flow, a circulatory disorder, or substantial blood loss that would impair the transfer of oxygen and nutrients. Each of these examples would lead to increased lactate levels and promote muscle fatigue.

Aerobic Metabolism in Skeletal Muscle

ATP is generated through aerobic metabolism 95% of the time during rest. Aerobic metabolism is a process by which mitochondria absorb oxygen, ADP, phosphate ions, and substrates from the cytoplasm. The substrates enter the Krebs cycle (also known as the citric acid cycle, or the tricarboxylic acid cycle), which is a pathway that breaks down these molecules to release the stored energy in the form of ATP, through the oxidation of acetyl-CoA. For more on this, refer to Chapter 23: Nutrition and Metabolism. When the skeletal muscle is at rest, the muscle fibers gain nearly all of the necessary ATP from aerobic metabolism of fatty acids. When the muscles start contracting, which requires greater amounts of energy, mitochondria begin breaking down pyruvic acid in addition to fatty acids.

Functions of Skeletal Muscle

All body movements, whether hiking a mountain or brushing your teeth, are produced from muscle contractions. The primary functions of the skeletal muscle include the following: Movement: Skeletal muscles create movement by contracting and pulling on tendons, which are inserted into the bones. Support: Muscles in the abdominal wall support visceral organs and shield tissues from injury. Posture: While movement is accomplished by skeletal muscle contractions, muscles also continuously contract to hold the body still and maintain an upright sitting or standing posture. Temperature Regulation: Skeletal muscle is about 40% of body mass, which gives it a disproportionate effect on body temperature. Communication: Skeletal muscles facilitate all modes of interpersonal communication, including speaking, typing, writing, facial expressions, and gestures.

When a person dies and rigor mortis occurs, which molecule causes the maintenance of a constant muscle contraction? Ca^2+ ATP sodium oxygen

Ca^2+

Match the following structural and functional differences to the respective muscle type

Contractions are involuntary¸ slower¸ and are able to endure.=smooth muscle When it contracts¸ the muscle cell twists in a spiral-like fashion=smooth muscle skeletal muscle=A pull on the tendons are inserted into the bones to create movement. skeletal muscle=Hundreds or even thousands of fibers are bundled together and wrapped by a connective tissue covering. smooth muscle=This type has the ability to maintain contractibility over a wide range of lengths.

case study;Cumulative trauma

Cumulative trauma disorders refer to a collection of disorders associated with nerves, muscles, tendons, bones, and related blood vessels. Cumulative trauma disorders usually result from carrying out a repetitive physical task without following the proper biomechanics. Cumulative trauma disorders are common in people who carry out repetitive tasks with the extremities placed in awkward positions, or with great force or speed. The disorders are made worse by insufficient rest and inadequate recovery times. These disorders commonly involve the neck, back, shoulders, arms, wrists, or hands, and usually involve pain, joint irritability, swelling, and an inability to carry out normal activities. Common disorders of this type are tennis elbow, knee sprains, ankle sprains, and back injuries.

exactly whats on practical exam picture and muscular terms of the Muscles of the Hip Region

Gluteus maximus Gluteus medius Gluteus minimus Hip flexors (Psoas major and Ilicus)

exactly whats on practical exam picture and muscular terms of the Muscles of the Back Shoulder & Chest

Erector spinae-Unilateral contraction of erector spinae results in lateral flexion (ipsilateral) and rotation of the cervical, thoracic spine and lumbar spines. Bilateral contraction of erector spinae causes extension of the head, neck and cervical, thoracic and lumbar vertebrae. Latissimus dorsi-extends arm at shoulder joint and adducts humerus, and medially rotate arm at shoulder joint. Trapezius-elevates, depresses, retracts. rotate the arm and adducts scapula Rhomboids- scapular retraction,rotate, elevate around the scapulothoracic joint. Deltoid-abducts humerus/arm Pectoralis major-adducts, medially rotate arm, flex humerus

Which of the following statement(s) regarding the effects of inactivity is/are true? People who live an active lifestyle maintain physical functioning and muscular fitness. The amount of muscle mass a person has is exclusively determined by their genetics. When muscle fibers are not activated regularly they atrophy. People who spend too much time in sedentary behaviors will lose skeletal muscle mass and tone.

People who live an active lifestyle maintain physical functioning and muscular fitness. When muscle fibers are not activated regularly they atrophy. People who spend too much time in sedentary behaviors will lose skeletal muscle mass and tone.

ATP Regulates Cross-Bridge Formation

The cross-bridge cycle in skeletal muscle consists of the following events: Step 1: A cross-bridge forms between actin and myosin when Ca2+Ca2+is released from the sarcoplasmic reticulum and binds to troponin. This binding changes the conformation of troponin, causing it to rotate in a way that it allows the myosin head to attach to the binding site of actin. When ATP binds to the myosin head and hydrolyzes to ADP and inorganic phosphate, this activates the myosin head, putting in it a cocked conformation (or high-energy state). This allows myosin to bind to actin. During this first step of the cross-bridge cycle, inorganic phosphate is released, which makes the interaction between myosin and actin stronger. Step 2: The power stroke occurs as ADP dissociates from the myosin head and the now-activated myosin head pivots, sliding the actin fiber toward the center of the sarcomere and moving the myosin head to a rigor-like conformation (or low-energy state). Step 3: The cross-bridge detaches as another ATP molecule binds to myosin, causing the myosin-actin interaction to weaken and myosin to dissociate. Step 4: The myosin head is reactivated when ATP is hydrolyzed to ADP and inorganic phosphate. The energy released through hydrolysis returns the myosin head back to its activated position. This four-step cross-bridge cycle (cross-bridge, power stroke, dissociate, reactivate) continues as long as Ca2+Ca2+and ATP are available, which exposes the myosin attachment sites on actin to allow for cross-bridge formation. As this cycle repeats, sarcomeres are pulled toward their center, leading to muscle shortening and contraction.

The Sliding Filament Model of Skeletal Muscle Contraction

The sarcomere, as the smallest contractile unit of the skeletal muscle, gives a clear example of how structure at the molecular level determines function at the macro-scale. This is because, in this example, the sliding of the sarcomere "scales up" to produce muscle contraction. Filament sliding occurs when Ca2+Ca2+levels rise due to excitation-contraction coupling. This process begins when Ca2+Ca2+released from the sarcoplasmic reticulum binds to the regulatory protein troponin-C, which is a part of the troponin complex. When bound to Ca2+Ca2+, the three-dimensional shape of troponin-C changes, causing it to move tropomyosin. Tropomyosin is a regulatory protein that normally blocks the binding sites for the myosin heads on F-actin. When calcium binds to troponin-C, tropomyosin moves out of this binding site, and actin and myosin filaments form cross-bridges. Relaxation occurs as Ca2+Ca2+ is pumped into the sarcoplasmic reticulum through the action of the Sarcoplasmic/Endoplasmic Reticulum �a2+Ca2+ATPase (SERCA). Active transport is necessary because the concentration of Ca2+Ca2+is higher in the sarcoplasmic reticulum than in the cytosol (even during contraction). The decrease in sarcoplasmic Ca2+Ca2+causes Ca2+Ca2+to dissociate from troponin, allowing tropomyosin to, once again, block the myosin binding sites on F-actin. This leads to relaxation of the muscle fiber.

Identify the nucleus of a smooth muscle cell.

in the center

Do muscles only push, only pull, or do they both push and pull?

muscles only pull. yes, we can push things away from our bodies with our arms or legs (e.g. a push up). however, a pushing movement is a function of the muscles pulling toward their center

What topic did you understand the least from this chapter? Explain. (Remember that we are looking for what you understood the least and not necessarily something that you didn't understand.)

tension production in skeletal muscle

Gross Anatomy of Skeletal Muscle

The human body has more than 650 skeletal muscles, each of which is formed from an elaborate system of tubes within tubes (similar to the osteon, or Haversian system, in bone) as shown in Figure 9.3. Each muscle is wrapped in a connective tissue layer known as the epimysium, which wraps together bundles of muscle fibers (muscle cells) that run the entire length of the muscle. Each of these bundles is known as a fascicle (or fasciculus) and each muscle fiber within a fascicle is itself surrounded by a connective tissue layer known as the endomysium. ​The epimysium and perimysium provide anchorage and support to nerves and blood vessels that innervate and supply energy to the muscle fibers. All connective tissues in the muscle—the epimysium, perimysium, and endomysium—are contiguous with the tendons at the end of the muscles and attach to the periosteum (Chapter 5: Bones and Axial Skeleton). Why is the connective tissue contiguous with the periosteum? Contraction of the muscle pulls on the tendon which, in turn, pulls on the periosteum to which it is attached. This moves the bone to a new position.

Energetics of Muscle Activity

After reading the section on the sliding filament model, it should be clear that energy in the form of ATP is necessary for a muscle fiber to contract. In the human body, energy is stored in several primary forms (e.g., carbohydrates, fats, proteins, and phosphocreatine) in different locations in the body. Furthermore, there are different methods by which ATP is generated in the muscle, including aerobic metabolism and glycolysis. These different metabolic systems are used to generate ATP based on the demands placed on the muscles; in other words, energy is generated at the rate at which energy is required. Let's look at a practical example of the rate of energy consumption in a skeletal muscle. The average male bicep is 30 cm, and the average sarcomere length is 3 microns. This means that there are about 105105 sarcomeres within one fiber of the biceps, with each sarcomere forming approximately 100-200 cross-bridges with actin. Now consider that the action of lifting a coffee cup from the counter to your mouth requires almost complete shortening of the bicep. This means that 100-200 ATP molecules are consumed in each sarcomere, or 107107in the whole fiber. With 100s of fibers in each bicep, lifting a cup of coffee requires billions of ATP molecules. This may sound like a lot of ATP—and it is—but to put it in perspective, one billion ATP molecules are equal to less than 1 kilocalorie (commonly referred to as a calorie).

Energy Use and the Level of Muscle Activity

As shown if Figure 9.20, different levels of muscle activity require different methods of metabolism. When ATP demands in a skeletal muscle are low, there is more than enough oxygen available in the muscle to produce ATP, and there is a surplus of energy. This extra ATP is used to produce creatine phosphate and glycogen stores. When a muscle contraction begins at moderate levels of activity, more ATP is needed. At this intensity, demands can be met by aerobic metabolism via mitochondrial ATP production. As muscle activity and ATP production increase, so does oxygen consumption. At this stage, all of the ATP that is produced is needed by the muscle fibers, and no surplus is available. The muscle then utilizes the aerobic metabolism of pyruvic acid from glycolysis to produce ATP. As long as ATP demands can be met by aerobic metabolism through the mitochondria, the contribution from glycolysis remains low. However, when higher levels of muscular activity are required and energy demands are large, aerobic metabolism must work at its maximum capacity. This maximum capacity is determined by the availability of oxygen. At peak levels of exertion, aerobic metabolism can only provide about one-third of the necessary ATP. At this time, pyruvic acid can also be broken down without oxygen through glycolysis, which supplies the remainder of ATP needed but at the cost of lactic acid accumulation. When pyruvic acid is produced by glycolysis faster in the cells than it can be used through aerobic metabolism in the mitochondria, pyruvic acid levels in the sarcoplasm rise. When this occurs, pyruvic acid is converted to lactic acid. This anaerobic process allows the cell to make additional ATP when the mitochondria are unable to keep up with energy demands. However, anaerobic metabolism has its disadvantages: It decreases cellular cellular pH (acidity). The production of lactic acid lowers intracellular pH when buffers of this acidity shift are limited. Eventually, pH levels will alter the functional ability of key enzymes in the cell and muscle fiber contraction cannot continue. It is an inefficient method of ATP generation. Under anaerobic conditions, glycolysis produces two pyruvic acid molecules that are converted to lactic acid. As a result, two ATP molecules are produced through glycolysis. To provide perspective, if those same two pyruvic acid molecules were broken down in a mitochondrion via aerobic metabolism, 34 ATP would be produced.

Describe how the action of pectoralis major and latissimus dorsi will help you swim a free style stroke.

As you lift your arm up and into the water to begin the stroke, the pectoralis muscle will allow you to flex, adduct, and rotate it medially. As you pull your arm through the water, the latissimus dorsi contracts to extend, adduct, and rotate the arm medially. These two muscles' alternate actions will propel you through the water.

exactly whats on practical exam picture and muscular terms of the Muscles of the Hip Region

Gluteus maximus-extend, laterally rotate the thigh at hip joint. Gluteus medius-hip abduction steadies pelvis while walking, medially rotate the thigh at hip joint. Important for stabilization and maintaining the normal positioning of the pelvis during walking. Gluteus minimus-predominantly acts as a hip stabilizer and abductor of the hip, and medial rotation of hip joint Hip flexors (Psoas major and Ilicus)-flexion of the hip

Skeletal Muscle Tone

In addition to force generation, coordinated control over motor units also creates muscle tone, which is the ability of a muscle to maintain a continuous and passive partial contraction. The maintenance of muscle tone is particularly important for posture, balance, and preventing injury. Have you ever wondered why some people have higher levels of muscle tone than others, like the individual in Figure 9.15 above? Muscle tone is determined by the structure of the muscle, which includes the connective tissue that holds the muscle together, and the size of the elastic component titin within the muscle fiber. The size of the titin protein is influenced by loading. The more the muscle is "loaded" via exercise and activity, the larger titin becomes. This is one reason why strong muscles have more tone. The degree of active, or responsive, muscle tone, is the second factor that determines muscle tone. Once again, individuals who are more physically active have higher levels of active muscle tone. In other words, a greater number of their motor units are stimulated even when the muscle is at rest. This gives the muscle the appearance of being firm and well-defined under resting conditions. People who are leaner (have less body fat) might appear more toned; however, they may or may not have more muscle tone. It could be that their muscle is simply not hidden by a layer of subcutaneous fat. Resting muscle tone varies by individual and ranges from low-muscle tone, which is associated with greater levels of flexibility of the muscle and joint, to high-muscle tone, which is associated with greater levels of strength and power. However, there are exceptions to this relationship. For example, a person could have a high-muscle tone and a hypermobile joint, which would mean they are likely both strong and flexible through that joint's range of motion. Specifically, a male could be very strong through the lower body, having a high-muscle tone through the hamstrings and gluteals. He may also have unusual flexibility through the knee and hip joint which allow him to touch his toes with his legs straight. A highly toned male who is able to squat a relatively heavy amount and still touch his toes is unusual.

case study A 6-year-old boy was brought to the ER because his mother was concerned that he had a strange way of walking, he was falling for no reason, and he seemed to tire easily. On physical examination, the young man had very well-developed gastrocnemius muscles in both legs. When asked to walk, his gait was abnormal and he nearly fell twice. When asked to stand up from a lying position, the boy struggled to do so (this is known as Gower's sign, caused by weak peripheral muscles). There is no evidence that anyone else on his mother's side of the family suffers from the same problem. The physician ordered a muscle biopsy. What is the likely problem the patient is suffering from and why did they ask for a muscle biopsy? Multiple sclerosis, to look for the type of muscle damage Muscular dystrophy, to look for the absence of dystrophin Cerebellar atrophy, to look for muscle wasting Amyotrophic lateral sclerosis, to look for loss of muscle mass

Muscular dystrophy, to look for the absence of dystrophin

exactly whats on practical exam picture and muscular terms of the head

Occipitofrontalis (Frontalis)-Action (raises eyebrows) movement:moves forward eyebrows and forehead, and draws scalp back. Orbicularis oculi-action (blinks and closes eyes) movement:tightly closes the eyes during winking Orbicularis oris-action (closes and protrudes lips) Zygomaticus-action (raises corner of mouth) movement-pulls corners of mouth (smiling muscle) Masseter-action (closes jaw) and elevates mandible Sternocleidomastoid-action (flexes neck, bending, contraleteral rotation of the head) (rotates head)

A 24-year-old female presents to the ED complaining of intermittent severe pain in her lower legs. She states that this has been occurring since she started preparing for her first marathon last month. She notes that the pain seems to start in the calf area and spreads around to the front of her lower leg over time. She describes the pain as slow onset and leading up to the most excruciating pain she has ever felt, though she can't exactly pinpoint where the pain is other than her lower leg. She has tried to push through the pain, but it eventually becomes too intense and she has to stop running. The pain does seem to improve after she stops and rests for a while, and it seems to be limited to her left leg. She also remembers that she gets a tingling, pinprick sensation in her foot. What is the likely problem the patient is suffering from? She has sciatica (a painful inflammation of the sciatic nerve in the posterior leg). She has multiple sclerosis which is causing the pinprick sensations. She has compartment syndrome that is causing the pain. She is unfit for the marathon and needs to eat healthier.

She has compartment syndrome that is causing the pain.

Which of the following is NOT true regarding differences in smooth and skeletal muscle? There are more cross-bridges in smooth muscle cells than skeletal muscle cells. Smooth muscle can produce more force and achieve a greater change in size than skeletal muscle. Smooth muscle cells are involuntary, slower, and able to endure longer than skeletal muscle. Smooth muscle cells are under more conscious control than skeletal muscles.

Smooth muscle cells are under more conscious control than skeletal muscles.

Which of the following statement(s) is/are true regarding altering characteristics of muscle fiber types? Select all that apply. transformation within muscle fiber subtypes has been demonstrated. Type I to type II transitions¸ and vice versa¸ appear less probable. Even if fiber types do not change¸ every person can improve in aerobic endurance¸ strength¸ and power. Fiber types are determined exclusively by the SAID principle and are altered with proper training.

Transformation within muscle fiber subtypes has been demonstrated. Type I to type II transitions¸ and vice versa¸ appear less probable. Even if fiber types do not change¸ every person can improve in aerobic endurance¸ strength¸ and power.

case study:Rigor Mortis

When a person dies, circulation stops and the skeletal muscles no longer have the nutrients and oxygen necessary to maintain life. Within a few hours, the skeletal muscle fibers become depleted of ATP, rendering them unable to pump Ca2+Ca2+out of the sarcoplasm. The persistence of Ca2+Ca2+in the sarcoplasm, either due to leak out of the sarcoplasmic reticulum or leak into the cell from the extracellular fluid, leads to constant muscle contraction. This is compounded by the fact that ATP is also necessary for breaking cross-bridges. When the muscles throughout the body are in a permanent state of muscle contraction, called rigor mortis, the body becomes "as stiff as a board." This lasts from 4-18 hours depending on environmental factors. Rigor mortis is terminated when lysosomal enzymes are released by autolysis to break down the myofilaments. Forensic pathologists can estimate how long a person has been dead based on environmental characteristics and the degree of rigor mortis.

Recovery

When the muscle is at rest after exertion, conditions in the fibers begin to return to normal pre-activity levels; this is called the recovery period. It may take a muscle several hours to return to normal after moderate exertion and up to a week after sustained intense activity. 9.3.3.A Lactic Acid Removal Glycolysis allows the muscle to continue to contract even when the mitochondria have an oxygen deficit. Glycolysis, however, is not a very efficient method of producing ATP, as it produces lactic acid as a byproduct, which will ultimately lead to muscular fatigue. When muscular activity decreases and more oxygen is available, lactic acid can be recycled back to pyruvic acid and used by the mitochondria to generate ATP or to rebuild glycogen reserves. Therefore, the lactic acid is reused in the muscle as energy. Additionally, when exertion levels remain high, lactic acid is shuttled out of the muscle fibers and into the bloodstream, where it travels to the liver to be absorbed and converted to pyruvic acid. About 30% of the pyruvic acid molecules are broken down in the Krebs cycle. This provides the ATP needed to convert the other pyruvic acid molecules to glucose. The glucose is then sent to the bloodstream, where it is reabsorbed in the muscle fiber to be rebuilt into glycogen reserves. This process of shuttling lactic acid from the muscle fiber into the bloodstream, and then to the liver, and then sending glucose back to the bloodstream, and finally back to the muscle, is called the Cori cycle.

case study:Rhabdomyolysis

While it is important to achieve a level of activity in order to maintain muscular health and physical functioning, too much exercise at too high an intensity is also harmful to muscular health. Rhabdomyolysis is a serious syndrome that results from muscular injury. The condition results from the death of muscle fibers and release of their contents into the bloodstream. Because the kidneys are responsible for filtering the blood, this condition can overload the kidneys and cause kidney failure, permanent muscle damage, and in rare cases death. In people with rhabdomyolysis, the kidneys become unable to filter waste from the bloodstream and the urine becomes extremely concentrated, as in Figure 10.19. There are several causes of rhabdomyolysis, including a muscular injury from a car crash, drug abuse, some medications, and extreme muscle strain from exercise. Rhabdomyolysis from exercise is incredibly rare but generally occurs when untrained individuals do too much exercise at too high an intensity. Therefore, it is important for beginner exercisers to start out at a low intensity and increase their total volume and intensity of exercise gradually.

Respiratory Rate and Muscle Contractions

You have likely noticed that as you work harder or move faster, your respiratory rate (breathing pattern) increases (Figure 9.19). But have you stopped to consider why this happens and what purpose this serves? As described in the process of aerobic metabolism, as work output increases, skeletal muscles require more energy, which necessitates more oxygen and the need to release more carbon dioxide. With an increase in one's respiratory rate, greater amounts of oxygen are absorbed through inhalation and more carbon dioxide is released through exhalation. The next time your rate of physical activity increases, you will understand the cellular-level reasoning behind the corresponding increase in respiratory rate.

Select the muscle of the quadriceps that allows you to flex your hip and extend your leg

central muslce

Assuming a light load, which of the following will happen the fastest? eccentric contraction concentric contraction isometric contraction

concentric contraction

Muscles of upper arm

deltoid-abduction of the arm at the shoulder joint after initiation. The muscles of the rotator cuff include the supraspinatus, infraspinatus, teres minor, and subscapularis muscles. The supraspinatus muscle originates on the posterior scapula in the supraspinous fossa and inserts on the greater tubercle of the humerus. The supraspinatus muscle acts to abduct the arm at the shoulder joint. The infraspinatus muscle originates in the infraspinous fossa of the scapula and inserts on the greater tubercle of the humerus. The teres minor muscle originates on the posterior inferior surface of the lateral border of the scapula and inserts on the greater tubercle. Both the infraspinatus and teres minor muscles act to laterally rotate the arm at the shoulder joint. Finally, the subscapularis muscle originates on the subscapular fossa on the anterior scapula and inserts on the lesser tubercle of the humerus. The subscapularis muscle acts to medially rotate the arm at the shoulder joint. biceps brachii-The biceps brachii muscle will flex forearm at the elbow joint and weakly flex the arm at the shoulder joint. triceps brachii-Thus, all three heads heads will extend the forearm at the elbow joint, while the long head will also extend the arm at the shoulder joint. Brachialis-The brachialis muscle is the primary muscle that flexes the forearm at the elbow joint. brachioradialis-it flexes the forearm at the elbow joint. It also functions to supinate and pronate from midposition (thumbs facing anterior and palms medial).

What is the sequence of events that converts action potentials in a muscle fiber to a contraction? muscle fiber recruitment post activation potentiation excitation contraction coupling the all-or-nothing principle

excitation contraction coupling

Muscles of the hip, thigh, and leg

gluteus maximus-it functions to extend and laterally (externally) rotate the thigh at the hip joint. gluteus medius-it will abduct and medially (internally) rotate the thigh at the hip joint. This muscle is also important in hip stabilization and maintaining the normal positioning of the pelvis during walking. sartorius-will flex, abduct, and laterally rotate the hip and also flex the knee The quadriceps femoris group includes four muscles, including the rectus femoris, vastus medialis, vastus intermedius, and vastus lateralis. The vastus lateralis muscle is attached to the linea aspera of the femur and is located on the lateral thigh. The vastus medialis muscle is also attached to the linea aspera of the femur, and is located on the medial thigh. The vastus intermedius muscle (Fig 7.23 below) attaches to the anterior shaft of the femur and is located in between the vastus lateralis and vastus medialis muscles. Located superficial to these muscles is the rectus femoris muscle, which attaches proximally to the anterior inferior iliac spine (AIIS) of the ilium. All four muscles have a common distal attachment to the tibial tuberosity of the tibia through the quadriceps tendon, which houses the patella. As the quadriceps tendon continues distally to attach to the tibial tuberosity, it changes its name to the patellar ligament. The four quadriceps femoris muscles will extend the leg at the knee joint. In addition to leg extension, the rectus femoris muscle will also flex the thigh at the hip joint. This difference in action is because rectus femoris crosses both the hip and the knee joints, while the vastus muscles only cross the knee joint. gracilis-it will adduct the thigh at the hip joint and flex the leg at the knee joint. biceps femoris-they both will flex the leg at the knee joint, as well as laterally rotate the leg at the knee joint. However, the long head also crosses the hip joint and will therefore also extend and laterally rotate the thigh at the hip joint. The semitendinosus muscle-will extend the thigh at the hip joint and flex and medially rotate the leg at the knee joint. The semimembranosus muscle-will extend the thigh at the hip joint and flex and medially rotate the leg at the knee joint. tibialis anterior-It extends distally to the base of the first metatarsal and the medial cuneiform. It dorsiflexes the foot at the ankle joint and inverts the foot. gastrocnemius muscle-it flexes the leg at the knee joint and plantar flexes the foot at the ankle joint. the calcaneal tendon ("Achilles tendon"), and common distal attachment, the calcaneus The soleus-plantar flexes the foot at the ankle joint.

An activity that would require primarily anaerobic metabolism would be which of the following? low intensity like washing dishes high-intensity intermittent bouts like jumping rope moderate intensity like going on a walk running a 100m dash

high-intensity intermittent bouts like jumping rope

In what ways has your knowledge of aging and the effects of activity on the skeletal muscle moved you to reflect on your current and future lifestyle?

include anaerobic and aerobic exercise in life.

The gluteus ___________ muscle allows you to abduct and medially rotate your thigh at the hip joint

maximus

Delayed-onset muscle soreness is due to which of the following mechanisms? Select all that apply. microtears to the muscle fiber injury to the connective tissue lactic acid build up

microtears to the muscle fiber injury to the connective tissue

A 67-year-old female is brought to the ER for difficulty breathing and swallowing. The attending physician notes that she is also suffering from ptosis (one drooping eye). When asked to read back a notice on the wall, the patient tells the physician that everything appears to be doubled, which is resolved with one eye closed. The patient also has altered speech. What is the likely problem the patient is suffering from? multiple sclerosis muscle dystrophy myasthenia gravis amyotrophic lateral sclerosis

myasthenia gravis

Match the type of muscle with the corresponding tissues/structures.

nerves=skeletal muscle skeletal muscle=blood vessels skeletal muscle=connective tissues smooth muscle=caveolae smooth muscle=one nucleus per cell

Match the following structural and functional differences to the respective muscle type. non-striated¸ sheets of tissue that line hollow organs smooth muscle-skeletal muscle striated tissue under voluntary control of the nervous system wherein cells are lined up in sarcomeres and bundled together by connective tissue=skeletal muscle made up of muscle tissue¸ connective tissue¸ blood vessels¸ and nerves skeletal muscle=smooth muscle has more cross-bridges and is therefore able to produce more force with slower and enduring contractions=smooth muscle smooth muscle-scattered cells with greater plasticity and the ability to contract at a range of lengths

non-striated¸ sheets of tissue that line hollow organs= smooth muscle striated tissue under voluntary control of the nervous system wherein cells are lined up in sarcomeres and bundled together by connective tissue=skeletal muscle made up of muscle tissue¸ connective tissue¸ blood vessels¸ and nerves=skeletal muscle has more cross-bridges and is therefore able to produce more force with slower and enduring contractions=smooth muscle smooth muscle-scattered cells with greater plasticity and the ability to contract at a range of lengths

In order to create movement (and according to the sliding filament theory), muscles ________. push pull push and pull

pull

Skeletal muscle maintains heat in the body by doing which of the following? producing energy releasing heat with muscle contractions transferring heat from the air to the body absorbing heat from the sun

releasing heat with muscle contractions

Muscle tone increases as which of the following increases? age strength height body weight

strength

When muscle contraction occurs, which of the following is true? the H- and I-bands get larger the Z-disks move closer together the width of the I-band remains constant the Z-disk lengthens

the Z-disks move closer together

What is the name of the process wherein only the motor units and associated muscle fibers needed for a movement are stimulated? the all-or-nothing principle fiber recruitment rate of force development a phasic contraction

the all-or-nothing principle

The length-tension relationship of skeletal muscles is explained by which of the following? the length of time the muscle has contracted the amount of effort put forth by the muscle the amount of Ca in the muscle the forcefulness of the muscle contraction depends on the length of the sarcomeres within a muscle before the contraction occurs

the forcefulness of the muscle contraction depends on the length of the sarcomeres within a muscle before the contraction occurs

Muscles of the anterior chest wall and abdominal wall

the pectoralis major-The clavicular head and sternocostal head acting together wilh flex, adduct, and medially rotate the (arm at the glenohumeral joint). The clavicular head flexes the arm from an extended position, while the sternocostal head extends the arm from a flexed position. The external intercostal muscle-run in between ribs. On the outer side. During respiration contraction of the external intercostal muscles will elevate the rib cage. internal intercostal muscle-run in between ribs. During inhalation while the internal intercostal muscles will depress the rib cage during forced exhalation. external abdominal oblique-wrap around the lateral and anterior portions of the anterior abdominal wall.The anterolateral wall muscles work together to flex the trunk (think of doing your sit-ups), compress the abdominal cavity to increase intraabdominal pressure (when you cough, defecate, urinate, or during childbirth), and aid in rotating the trunk. abdominal oblique muscle-wrap around the lateral and anterior portions of the anterior abdominal wall.The anterolateral wall muscles work together to flex the trunk (think of doing your sit-ups), compress the abdominal cavity to increase intraabdominal pressure (when you cough, defecate, urinate, or during childbirth), and aid in rotating the trunk. rectus abdominis-wrap around the lateral and anterior portions of the anterior abdominal wall. The anterolateral wall muscles work together to flex the trunk (think of doing your sit-ups), compress the abdominal cavity to increase intraabdominal pressure (when you cough, defecate, urinate, or during childbirth), and aid in rotating the trunk.

Action potential propagation of an excitable membrane involves ________. an increase in the intensity of the contraction the same events taking place over and over the muscle slowly contracting a membrane being charged

the same events taking place over and over

Select the brachioradialis.

top of hand

Which of the following is not part of the erector spinae muscle group? Iliocostalis Longissimus Spinalis Trapezius

trapezius

Muscles of the back

trapezius-spans most of the back. Elevates, depresses, retracts, rotates the scapula, rotate the arm latissimus dorsi-inferior and deep to the trapezius muscle. it will function to extend the arm at the shoulder joint. It also will adduct and medially rotate the arm at the shoulder joint. The erector spinae muscle group contains three individual muscles: iliocostalis, longissimus, and spinalis. Iliocostalis is the most lateral of the three erector spinae muscles and will fan out superiorly to attach to the ribs. Longissimus in the longest of the three erector spinae muscles and is just medial to iliocostalis. Longissimus will extend from the sacrum and extends all the way to the skull. Spinalis is the most medial of the three muscles and extends from the thoracic region to the skull. The erector spinae muscles have both bilateral and unilateral actions. Bilaterally, the left and right erector spinae muscles work together as postural muscles to hold the spine erect and extend the head and vertebral column (backward bending). Unilaterally, the erector spinae muscles will lateral flex the vertebral column (side-bending).

What is the neuromuscular junction? where the axons of motor nerves meet the muscle a chemical synapse formed between a motor neuron and a muscle fiber the process of shuttling lactic acid from the muscle fiber into the blood strea

where the axons of motor nerves meet the muscle