Mastering A&P Chapter 6

What is the cardiac muscle responsible for?

• Generation of force necessary to pump blood • involuntary control of contraction • ability to contract without nervous system oversight • regeneration after injury is minimal, if any • joined to another muscle cell at an intercalated disc (junction of two adjoining cardiac cells)

Describe cartilage

• Type of connective tissue - softer and more flexible than bone • is avascular, found throughout the body and one important function is to cover bones at joints (articular cartilage)

Describe the body location and cell shape/ appearance of skeletal muscle:

• attached to bones, or for some facial muscles to skin • single, very long, cylindrical, multinucleate cells with very obvious striations

Flexion

• decreases the angle of the joint • brings two bones closer together • typical of bending hinge joints like knee and elbow or ball and socket joints like the hip

Plantar flexion

• depressing the foot (pointing the toes) • Planting the foot towards the sole

Dorsiflexion

• lifting the foot so that the superior surface approaches the shin (toward the dorsum)

Extension

• opposite of flexion • increases the angle between two bones • typical of straightening the elbow or knee • extension beyond 180 is hyperextension

Where does oxygen replenish ATP

• replenishes stores that were ised to run other reactions in the body (sped up by increased body heat) • speeds heart and breathing muscles using more ATP • oxygen replenishes ATP used in tissue repair processes

Skeletal Muscle Group: Fixators

• stabilize one of the bones so the agonist can move the other bone more efficiently

What is a neuromuscular junction?

• this is where the electrical impulse of the merve signal is converted to a chemical signal that binds to the muscle cell and starts an electrical impulse there (depolarization) • acetylcholine (ACh) is he chemical signal triggering depolarization • calcium triggers the release of acetylcholine

Describe the body location and cell shape/ appearance of cardiac muscle:

• walls of the heart • branching chains of cells, uninucleate striations; intercalated discs

What is the effect of resistance exercise?

• weight lifting increases muscle size and strength

What is the effect of aerobic exercise?

(biking, jogging) results in stronger, more flexible muscles with greater resistance to fatigue --> Makes body metabolism more efficient --> improves digestion and coordination

What specific event triggers the uncovering of the myosin binding site on actin?

Calcium ions bind to troponin and change its shape • The shape change caused by the binding of calcium to troponin shifts tropomyosin away from the myosin binding sites on actin

What causes muscles to contract less?

The increasing acidity from lactic acid and lack of ATP

What structure is the functional unit of contraction in a skeletal muscle fiber?

The sarcomere

What changes occur in the sarcomere during muscle contraction?

Z discs move closer together

The prefix epi means

above, upon, or over

What initiates an action potential on a muscle cell?

acetylcholine binding to receptors on the sarcolemma within the neuromuscular junction

There are three types of muscle tissue. Which of the following is classified as part of muscular system?

all skeletal systems

What is the role of muscle tissue?

allows for movement • body movement • organ movement helps us stay erect, relax when we sleep

Which of these increases as muscles age?

amount of connective tissue in a muscle

The prefix peri means

around

Fascia

attaches muscle to muscle • nervous system is related to skeletal muscle when not connected will result in paralysis • only muscle not dependent on nervous system is cardiac muscle

At its insertion (unlike at its origin) the buccinator muscle

attaches to fibers of another facial muscle

Why is a tendon injury hard to repair?

because there is little blood in the system

What type of muscle tissue is both striated and involuntary?

cardiac muscle

What is a neurotransmitter

chemical released by nerve upon arrival of nerve impulse - the neurotransmitter for skeletal muscle is acetylcholine

What term refers to a smooth, sustained comtraction

complete tetanus

The buccinator muscle

compresses the cheeks

What mineral is released within muscle cells to trigger contraction?

contraction

What is the function of creatine phophate

directly regenerates ATP from ADP within a muscle cell

The connective tissue covering the outside of a whole muscle is the

epimysium

The prefix iso means

equal or same

Which of these muscles is named for the arrangement of its fascicles?

external oblique

The buccinator muscle is innervated by the

facial nerve

The prefix sarco means

flesh

Both heads of the biceps and femoris muscle

flex the leg at the knee

What is the function of connective tissue?

function is to surround and protect muscular tissue

Which of these characteristics applies only to cardiac muscle tissue?

intercalated discs

The tibialis anterior muscle dorsiflexes the foot at the ankle and also assists in __________ of the foot.

inversion

The long head of the biceps femoris muscle originates on the

ischial tuberosity

A type of muscle contraction that generates force, but does not shorten the muscle is called

isometric

Distinguish between isotonic and isometric contractions

isotonic contractions require muscle movement of a bone; isometric contractions do not

The trapezius muscle may be separated into all of the following groups, except

lateral

How do bones attach to bones?

ligaments

Describe the body location and cell shape/ appearance of smooth muscle:

mostly in walls of hollow visceral organs (other than the heart) • single, fusiform, uninuclear, no striations (no conscious control)

The prefix myo means

muscle

Skeletal muscles work in what kind of groups

muscles work in agtagonistic pairs (opposing actions) with parts like prime mover, antagonists synergist, fixators

How do skeletal muscle contract?

must be stimulated by a motor neuron (nerve cell) to contract (triggered in the presence of calcium)

The part of a muscle fiber that contracts is called a/an

myofibril

What initiates skeletal muscle contraction

nerve signals initiate the voluntary or involuntary contraction

What is a motor unit

one motor neuron and all the skeletal muscle cells (sodium-potassium exchange) stimulated by that neuron

What is a common cause of muscle fatigue?

oxygen debt • oxygen must be repaid to tissue to remove oxygen deficit • oxygen is required to get rid of accumulated lactic acid • not enough oxygen for functioning die to strenuous exercise/ physical activity

The connective tissue covering around a fascicle is the

perimysium

The bicep femoris is located in the

posterior thigh

What is ROM

refers to selected muscle action on bones related to directional movement

What can older individuals do to increase muscle strength?

regularly use hand weights and practice leg lifts

The structural and functional unit of skeletal muscle is called a/an

sarcomere

All the fibers of the trapezius muscle are innervated by the

spinal accessory nerve

What is the role of adipose tissue?

stores body's triglycerides; serves as insulating layer to reduce heat loss and protects muscles from trauma

What are the components of the connective tissue?

subcutaneous layer (hypodermis) separates muscle from skin (part of integumentary system) • composed of areolar connective tissue and adipose tissue • pathways for nerves, blood vessels, and lymph to enter and exit muscles

Which movement is associated with the hand but actually occurs in the forearm

supination

What is epimysium?

surrounds entire muscle

How do muscles attach to bones?

tendons • cord like structures • mostly collagen fibers often cross a joint due to toughness and small size

What is the all or noting reaction?

you need calcium to release acetylcholine which is transported out of junctions which touches the sarcolemmas which stimulated Na+ K+ pump for muscle to contract

Calcium ions couple excitation of a skeletal muscle fiber to contraction of the fiber. Where are calcium ions stored within the fiber?

• Calcium ions are stored in the sarcoplasmic reticulum

Stimulation and Contraction of Single Skeletal Muscle Cells:

• Excitability • Contractability • Extensibility • Elasticity

Supination

• Forearm rotates medially so palm faces posteriorly • Radius and ulna cross each other like an X

After a power stroke, the myosin head must detach from actin before another power stroke can occur. What causes cross bridge detachment?

ATP binds to the myosin head • The binding of ATP to the myosin head weakens the bond between myosin and actin, forcing the myosin head to detach. ATP also provides the energy for the next power stroke.

What are the 5 golden rules of skeletal muscle activity?

1. With few exceptions, all skeletal muscles cross at least one joint 2. Typically, the bulk of a skeletal muscle lies proximal to the joint crossed 3. All skeletal muscles can only pull; they never push 4. Skeletal muscle can only pull; they never push 5. During contraction, a skeletal muscle insertion moves towards the origin

The cross bridge cycle is a series of molecular events that occur after excitation of the sarcolemma. What is a cross bridge?

A myosin head is bound to actin • As soon as the activated myosin head forms a cross bridge with actin, the power stroke begins.

When does the cross bridge cycling end

Cross bridge cycling ends when sufficient calcium has been actively transported back into the sarcoplasmic reticulum to allow calcium to unbind from troponin. • The sarcoplasmic reticulum contains Ca2+-ATPases that actively transport Ca2+ into the SR. Without Ca2+, troponin returns to its resting shape, and tropomyosin glides over and covers the myosin binding sites on actin.

Which of these terms refers to the shape of a muscle?

Deltoid

Effect of Exercise on Muscles

Exercise increases muscle size, strength, and endurance

Describe the effects of exercise on different types of skeletal muscle fibers

Exercise increases muscle size, strength, and endurance • Aerobic (endurance) exercise • Resistance (isometric) exercise

Types of body movements

Flexion, extension, dorsiflexion, plantar, flexion, supination, pronation

Skeletal Muscle Group: Synergist

Helps the agonist function more efficiently by reducing unnecessary movements • ex small muscle

Skeletal Muscle Group: Prime move/ agonist

Muscle that starts the desired action • ex bicep

Skeletal Muscle Group: Antagonist

Muscle with the opposing action to the agonist • tricep

Isotonic Contractions

Myofilaments are able to slide past each other during contractions • The muscle shortens and movement occurs --> Example: bending the knee; rotating the arm

Compare the main structural, functional, and special characteristics of the three types of muscle tissue

Smooth, skeletal and cardiac muscles are structurally different to perform specific functions

Isometric Contractions

Tensions in the muscles increases • The muscle is unable to shorten or produce movement Example: push against a well with bent elbows

How does the myosin head obtain the energy required for activation

The energy comes from the hydrolysis of ATP • Myosin is a large, complex protein with a binding site for actin. It also contains an ATPase. The energy released during the hydrolysis of ATP activates the myosin head.

Discuss the concepts of insertion, origin, and belly in relationship to muscle movement

Two bones are involved for movement of joint; one stationary, the other moveable • insertion is the term referring to the end of muscle attached to a moveable bone (via tendon) • origin is the term for the end of the muscle that attaches to an immovable/stationary bone • belly is the portion of muscle between the tendons of the origin and insertion