Anatomy & Physiology (Ch. 9)

Front 1

What do muscles connect?

Back 1

Muscles connect bone by tendons.

Front 2

What is a tendon?

Back 2

Dense regular connective tissue, serves as site of connection. Origin (non moving) to insertion (mover)

Front 3

What are the 3 connective tissue layers in a muscle?

Back 3

1. Epimysium- around the whole muscle

2. Perimysium- bundles of muscle fibers

3. Endomysium- individual muscles

These are how muscles create a pulling force on the bone.

Front 4

What are myoblasts?

Back 4

Early muscle cells fused into one cell with each having a nucleus. Some of the longest cells in the body. Myoblasts develop into myocytes.

Front 5

Describe the major properties of skeletal muscle cells

Back 5

1. Contractility- get shorter

2. Extensibility- get longer

3. Elasticity- return to original length

4. Excitiablility- can respond to and create electro chemical signals (membrane potential)

Front 6

Define sarcomere

Back 6

Part of a myofibril, capable of contracting, separated by Z disks, contain actin and myosin myofilaments. Functional unit of the skeletal muscle contraction

Front 7

Define sarcolemma

Back 7

Plasma membrane of a muscle fiber/cell

Front 8

Define sarcoplasmic reticulum (SR)

Back 8

Yellow, specialized version of endoplasmic reticulum of a muscle. Smooth, no ribosome. Specialized to store and release CA++ ions. SR is close together with T tubules.

Front 9

Define T tubule

Back 9

Transverse tubule, that extends from the sarcolemma to a myofibril of striated muscles. Inward projection of the cell membrane. Sarcolemma that runs through the cell. Things fall through it.

Front 10

Define sarcoplasm

Back 10

Cytoplasm of a muscle fiber

Front 11

Define triad

Back 11

Structure formed by a t tubule with SR on either side called terminal cisternae.

Consists of terminal cisternae, t tubule, terminal cisternae

Front 12

Compare/define muscles, muscle fibers, myofibrils and myofilaments

Back 12

Muscles- contain many muscle fibers that function to move and maintain parts of the body and contract.

Muscle fibers- composed of numerous myofibrils that contract when stimulated, combine to form muscles.

Myofibrils- long filaments that run parallel to each other to form muscle fibers. Where muscle protein is found. Cylinder inside a cylinder (muscle fiber)

Myofilament- filaments of myofibrils constructed of actin or myosin. Thin myofilaments= actin, thick myofilaments= myosin.

Front 13

Describe actin and myosin

Back 13

Myofibrils contain 2 myofilaments:

thin myofilaments called actin and thick myofilaments called myosin.

Actin- act as active sites for myosin to bind to. Composed of 2 actin protein molecules, TROPOMYOSIN normally covering the active sites. And TROPONIN which binds to actin, tropomyosin and CA++.

Myosin- myosin heads bind to active sites on actin. Heads 1. grab and pull and 2. Release ATP and reposition. They also are ATPase enzymes that break down ATP.

Front 14

Define Z disk

Back 14

Zig zag, filaments that form an anchor for attachment of actin myofilaments.

Front 15

Define I-band

Back 15

Consists of only actin myofilaments

Front 16

Define A-band

Back 16

Consists of both actin and myosin myofilaments

Front 17

Define H-zone

Back 17

Consists of only myosin myofilaments

Front 18

Define M-line

Back 18

Located down the middle of myosin myofilaments

Front 19

What is a myograph? How does it differ from a length tension graph?

Back 19

A myograph is used to measure the force produced by a muscle when under contraction.

A length tension graph measures length of the muscle when contracting.

Front 20

What are the 4 diff. types of myographs?

Back 20

1. Single twitch

2. Complete/fused tetanus

3 incomplete/unfused tetanus

4. Treppe

Front 21

What is a single twitch myograph?

Back 21

A single twitch is the contraction of a single muscle fiber.

Front 22

What is the difference between a complete/fused tetanus myograph and a incomplete/unfused tetanus myograph?

Back 22

A complete/fused tetanus muscle fibers produce action potentials so rapidly that no relaxation occurs between them.

A incomplete/unfused tetanus muscle fibers partially relax between the contractions.

Front 23

What is a Treppe myograph?

Back 23

Treppe is a neuromuscular phenomenon where force increases with every twitch, relaxation does occur and after a few contractions, tension produced by all contractions are equal.

Front 24

Define the lag phase, contraction phase and the relaxation phase

Back 24

Lag phase: (latent period) is the gap between the time of stimulus application, to the motor neuron and to the the beginning of contraction

Contraction phase: is the time during which contraction occurs

Relaxation phase: time during which relaxation occurs

Front 25

What is wave summation?

Back 25

Increased tension produced as the frequency of contracting increases

Front 26

What is fatigue?

Back 26

The decline in ability of a muscle to generate force.

Temporary state of reduced work capacity.

Front 27

Describe the cell types in skeletal muscle

Back 27

- attached to bones

- very long & cylindrical

- multiple nuclei

- striated

- no special cell-to-cell attachments

Front 28

Describe the cell types for smooth muscle

Back 28

- Walls of hollow organs, blood vessels, eyes, glands and skin

- spindle shaped

- single nucleus, centrally located

- not striated

- gap junctions join some visceral smooth muscle cells together

Front 29

Describe the cell types in cardiac muscle

Back 29

- heart

- cylindrical & branched

- single nucleus centrally located

- striated

- intercated discs join cells to one another

Front 30

Describe the control mechanism in skeletal, smooth and cardiac muscle

Back 30

Skeletal- voluntary & involuntary

Smooth- involuntary

Cardiac- involuntary

Front 31

Describe the contractions for skeletal, smooth and cardiac muscle

Back 31

Skeletal- not capable of spontaneous contraction

Smooth- some smooth muse capable of spontaneous contraction

Cardiac- capable of spontaneous contraction

Front 32

How can differential recruitment of motor units produce contractions of "graded strength"?

Back 32

Differential recruitment is the activation of additional motor units to accomplish an increase in contractile, strength in muscle.

A motor unit is a single motor neuron and all the muscle it controls. The "graded strength" depends on the force needed. Smaller the weight-smaller the force and vice versa. The force of a contraction involves increasing the number of muscle fibers and motor units, this is through differential recruitment.

For the most force, it has to be just right, in between shortest andongest length.

Front 33

Memorize

Back 33

Front 34

Explain the effects of exercise or lack of exercise on muscles

Back 34

Atrophy is a decrease in muscle size due to a decreased number of myofilaments. Can occur due to disuse or muscle or from chronic heart failure.

Hypertrophy is the enlargement of skeletal muscle due to an increased number of myofibrils, occurs with increased muscle use in cardiac muscle and hypertension.

Front 35

Diseases and disorders:

Define cramps

Back 35

Cramps are painful spastic contractions of skeletal muscles, due to multiple cause such as dehydration and ion imbalance

Front 36

Diseases and disorders: Define Duschenne muscular dystrophy

Back 36

Duschenne muscular dystrophy is an inherited disorder of progressive muscular weakness, Typically in boys

Front 37

Diseases and disorders: Define Myasthenia gravis

Back 37

Myasthenia gravis is a weakness and rapid fatigue of muscles under voluntary control. Results from the production of antibodies that bind to ACh receptors, eventually destroying the receptor and this reducing the number of receptors.

Ex. Difficulty swallowing, double vision, unsteady walk.

Front 38

Diseases and disorders: Define tendonitis

Back 38

Tendonitis is inflammation of a tendon or its attachment point due to overuse of a skeletal muscle

Front 39

Define lactic acid

Back 39

Lactic acid is produced in muscle tissue during strenuous exercise, that can lead to painful sore muscles.

Front 40

Whata the difference between aerobic endurance and anaerobic endurance?

Back 40

Aerobic endurance (cardiorespiratory endurance) refers to the ability of your cardiovascular and respiratory system- to sustain moderate intensity exercise over extended periods.

Anaerobic endurance refers to the ability to sustain intense, short duration activity such as weight lifting or sprinting

Front 41

Define oxygen deficit

Back 41

Oxygen deficit is the difference between oxygen intake of the body during early stages of exercise and during a similar duration in a steady state of exercise.

Front 42

What is myoglobin

Back 42

Myoglobin is a dark pigment which binds to oxygen and acts as a oxygen reservoir in the muscle fiber. This enhances the muscle fibers ability to perform aerobic respiration and the fibers with the more myoglobin are more fatigue resistant compared to those with low myoglobin.

Front 43

What are the functions of the human muscular system?

Back 43

1. Movement

2. Stability/posture

3. Heat production

4. Guarding entrances and exits

5. Nutrient reserves

Front 44

What is the relationship between length and tension in skeletal muscles?

Back 44

Active tension is the force applied to an object to be lifted when a muscle contacts. The initial length of a muscle has a strong influence on the amount of active tension it produces. As the length of the muscle increases, the active tension also increases , to a point. If the muscle stretches farther that its optimum length, the active tension it produces begins to decline.

Front 45

Describe the 4 different types of contractions in muscles

Back 45

1. Isometric: muscle produces INCREASING TENSION and the muscle DOES NOT CHANGE IN LENGTH.

2. Isotonic: muscle produces a CONSTANT TENSION.

..... 2a. Concentric: muscle shortens

..... 2b. Eccentric: muscle lengthens

Front 46

Describe the role of ATP in muscular contraction

Back 46

ATP provides energy for muscles, it is required for the cycle of the cross bridge formation, movement and release. ATP is also required to transport CA++ into the SR and to maintain normal concentration gradients across the plasma membrane. ATP binds to myosin and without it, muscle stays contracted.

Front 47

What are the sources of ATP in a muscle cell?

Back 47

- creatine phosphate (CP) conversion of CP to ATO.

- myoglobin which binds to oxygen so muscle cells can perform aerobics respiration to produce ATP. Low myoglobin leads to anaerobic glycolysis for ATP production.

Front 48

List and describe the two types of muscle fibers

Back 48

Slow-twitch (type I) contract more slowly, because their myosin heads have a slow form of myosin ATPase. But they have high myoglobin and are therefore highly fatigue resistant. These are typically smaller muscles.

Fast-twitch (type IIa and IIb) contract faster and break down ATP rapidly because their myosin heads have a fact form of myosin ATPase.

... type IIa (intermediate) have high myoglobin and intermediate fatigue resistance.

... type IIb have low myoglobin and low fatigue resistance

Front 49

List the steps in a skeletal muscle contraction

Back 49

1. A motor neuron release ACh into the synaptic cleft (gap between two cells) of the neuromuscular junction.

2. ACh binds to the ligand/chemically gated NA+ channels of the sarcolemma causing them to open.

3. Na+ (previously pumped out by the NA+K+ pump) will rush into the cell from the extracellular fluid. This influx of NA+ is called a "local" or "graded" potential. Could be small or big.

4. If the local potential is strong enough (if enough NA+ gets in), this will trigger the opening of the voltage-gated NA+ channels of the sarcolemma. Once the voltage-gates channels start to open, they will all open in a self propagating, unstoppable wave all over the sarcolemma and down the t-tubules. This is called an action potential.

5. The voltage wave passing down the t-tubules will trigger the opening of the voltage-gated CA++ channels found on the SR.

6. CA++ that was stored in the SR will rush out into the sarcoplasm.

7. The CA++ will bind tk the troponin proteins and the tropnonins will "change position, pivot, roll over, fall down" pulling the tropomyosin proteins off of the active sites on the actin filaments.

8. Once the active sites are exposed the myosin heads will attach to and pull or ratchet (repetitive motion) the actin filaments toward the center of the sarcomere. This would be the sliding filament idea.

Front 50

How does a muscle cell relax/return to its original length?

Back 50

1. Right after its released, ACh starts to be broken down by Acetylcholinesterase which is found floating around in the synaptic cleft and on the sarcolemma.

2. Once the ACh is broken down, the ligand/chemically-gated NA+ channels will close.

3. NA+ stops rushing into the cell

4. The voltage-gated NA+ and voltage-gated CA++ channels will also close.

5. The SR will actively pump the CA++ ions back in.

6. The troponins and tropmyosins will move back into their normal positions covering up the active sites.

7. Since the myosin heads can no longer attach to the actins they will slide black into their normal position.

Front 51

What about K+? Wasnt theres a bunch of K+ in the intracellular fluid at the start of this whole thing? What happens to it?

Back 51

There are also voltage-gated K+ in channels all over the sarcolemma, just like the voltage-gated NA+ channels.

They open as part of the action potential too, but they are sluggish, a low channels compared to the others.

So K+ does leave the cell, so we end up with NA+ on the inside and K+ on the outside. The NA+K+ pump will move them back to where they started, re-establishing the RMP