Bio 201 Exam 3 Muscles

What is a "triad" referring to?

1 t-tubule and 2 terminal cisternea

Which band of a sarcomere has actin and myosin?

A Band

Explain, in detail, the concept of a motor unit. How would the arrangement of a motor unit differ for fine control vs. strength control?

A motor unit is the motor neuron and the muscle fibers it innervates. Fine control: small motor unit, controls things like eye movement Strength control: larger motor unit

What is an aponeurosis? Where are some regions in the human body might you find one? How does an aponeurosis differ from a tendon?

A sheet like structure found in places like the bottom of the foot or palms of the hands. Aponeurosis is different from a tendon because a tendon is a cord like structure

Muscle cells are packed full of which type of protein filament?

Actin and myosin

Review the processes of anaerobic and aerobic respiration

Anaerobic is when there is a limited ATP production and produces more lactic acid, aerobic is when more ATP is produced and requires continuous oxygen supply

Discuss HOW myasthenia gravis leads to progressive weakness

Antibodies attack neuromuscular junction and bind ACh in clusters, results in drooping eyelids, double vision, weakness of limbs, etc.

What is the difference between a concentric and eccentric isotonic contraction?

Concentric is the same tension while shortening, eccentric is the same tension while lengthening

What is creatine phosphate in terms of a supplement? Specifically, who is it going to benefit? Why?

Creatine is what energy muscles need to work, this would mostly benefit body builders and athletes

What is DOMS?

Delayed Onset Muscle Soreness

Briefly summarize the four actions necessary for muscle contraction and relaxation.

Excitation = nerve action potentials lead to action potentials in muscle fiber Excitation-contraction coupling = action potentials on the sarcolemma activate myofilaments Contraction = shortening of muscle fiber Relaxation = return to resting length

Which zone of a sarcomere has only "bare" myosin?

H Zone

What types of things would an endurance athlete be concerned with? Explain!

Having enough carbohydrates and water

Which region of a myosin molecule attaches to actin?

Head

Describe what is occurring when a muscle goes into "oxygen debt." Make sure to explain EPOC in your response.

Heavy breathing after strenuous exercise, known as excess post exercise oxygen consumption

Which band of a sarcomere contains only actin?

I Band

Compare and contrast, in detail, what is occurring on a molecular and cellular level for immediate, short term, and long term energy needs of a muscle.

Immediate: used for short intense exercise like a brisk walk or 6 second sprinting. Uses phosphagen system. Short term: Glycogen-lactic acid system takes over Long term: Aerobic respiration needed for prolonged exercise

Compare and contrast isotonic and isometric muscle contraction. Give some examples of each.

Isometric contraction develops without changing lengths, Isotonic changes lengths- concentric is the same tension while shortening, eccentric is the same tension while lengthening

Describe the number and location of nuclei in a myofiber

Many nuclei under the sarcolemma

What is white muscle?

Mostly fast fibers (ex: chicken breast)

What is red muscle?

Mostly slow fibers (ex: chicken legs)

List AND describe the functions of skeletal muscles

Movement, posture, support, provides heat, storage of minerals

Explain, in detail, why an individual becomes rigid soon after death, but then days later, becomes floppy

Muscles stiffen 3 to 4 hours after death, occurs because of a massive release of calcium from the SR

What are two other names for a muscle fiber?

Myofiber, myocyte

Make sure you understand the difference between a myofiber and a myofibril

Myofiber=single muscle cell Myofibril=bundles of actin and myosin

What exactly is a cross bridge?

Myosin heads

Discuss HOW some of the neuromuscular toxins covered in class affect the NMJ.

Pesticides- prevent acetylcholinesterase from breaking down ACh, results in paralysis and possible suffocation Limp muscles due to curare that competes with ACh

Describe on a molecular and cellular level what is occurring when a muscle becomes fatigued.

Production of ATP declines as glycogen is consumed

List AND describe the characteristics of skeletal muscle

Responsiveness:(excitability) to chemical signals, stretch and electrical changes across the plasma membrane Conductivity: local electrical change triggers a wave of excitation that travels along the muscle fiber Contractility: shortens when stimulated Extensibility: capable of being stretched Elasticity: returns to its original resting length after being stretched

What is another name for the plasma membrane of a myofiber?

Sarcolemma

What is the name given to the contractile unit of muscle?

Sarcomere

What is another name for the muscle cytoplasm?

Sarcoplasm

What does recruitment mean in terms of muscle contraction?

Stimulation the whole nerve with higher and higher voltage, more motor units being recruited

Compare and contrast slow twitch and fast twitch muscle fibers.

Slow twitch: resistant to fatigue, slow to contract, found in back muscles Fast twitch: fatigue quickly, few mitochondria, found in arms

Explain what is meant by the statement that, "A muscle is never entirely relaxed."

Some muscle fibers are contracted even in a relaxed muscle state

How exactly do strength workouts increase muscle size?

Synthesis of more myofilaments

Describe the location of the T tubules, sarcoplasmic reticulum, and terminal cisternae. What is the function of each of these structures?

T tubules: circle around myofibrils, tunnel like infolding that penetrate the cell Sarcoplasmic Reticulum: network around each myofibril Terminal Cisternae: dilated end tracts which store calcium

What protein is the thin filament made of? What protein is the thick filament made of?

Thin: actin Thick: myosin

What is the function of a Titin protein? What two regions of the sarcomere does it connect?

Titin connects myosin to Z discs and aides in contraction and relaxation

Compare and contrast unfused and fused tetanus. Make sure to mention "treppe" and wave summation in your answer

Unfused (incomplete) tetanus: some relaxation occurs between contractions Fused (complete) tetanus: no evidence of relaxation before the following contractions

1. What happens to the sizes of the following bands/regions of sarcomere during contraction AND relaxation? a. Distance between Z - Lines b. Size of I - Band c. Size of A - Band d. Size of H - Zone e. Length of individual actin and myosin filaments

a. Stays the same b. Shortens c. Stays the same d. Shortens e. Stays the same

Describe, in detail, all of the components of a neuromuscular junction (NMJ) including: a. Synaptic knob b. Junctional folds c. Synaptic cleft d. Basal lamina e. Acetylcholine f. Acetylcholine receptors g. Aceytlcholinesterase

a. swollen end of nerve fiber which contains ACh b. increases surface area for ACh receptors, contains Acetylcholinesterase that breaks down ACh and causes relaxation c. tiny gap between nerve and muscle cells d. thin layer of collage and glycoprotein over all of muscle fiber e. neurotrasmitter released from nerve fiber f. Binding site g. breaks down ACh