Combined LJM TBL 3

What is the role of a fixator muscle?

Stabilises the origin of the prime mover

Which of the following muscles is a synergist in elbow flexion?

Brachialis

Which muscle functions as a fixator during elbow joint motion?

Subscapularis

What is true of synergist muscles?

They share a similar function as part of a muscle group

Which is an example of a synergist group for knee joint flexion?

Biceps femoris, semimembranosus, and semitendinosus

hat best describes a muscle acting as an agonist?

The muscle generating the net torque for movement

What is the functional role of the antagonist muscle?

Controls and modulates the agonist’s action

What is the primary mechanism of increased muscle size due to resistance training?

Hypertrophy through increased contractile protein volume

What term describes the increase in the volume of contractile proteins per muscle fibre?

Hypertrophy

Which of the following statements best defines hyperplasia?

Increase in the number of muscle fibres

What occurs in skeletal muscle following prolonged immobilisation?

Atrophy

What is the recommended clinical strategy following injury to reduce muscle atrophy?

Passive mobilisation followed by gradual loading

Which connective tissue layer surrounds individual muscle fibres?

Endomysium

In ageing muscle, what happens to the connective tissue volume?

It increases and contributes to muscle stiffness

What is a major functional outcome of reduced contractile proteins in ageing muscle?

Reduced strength generation

Muscle stiffness in ageing is largely due to:

Increase in collagen-rich connective tissue

Which change most directly leads to reduced flexibility in aged skeletal muscle?

Combined reduction in strength and increased stiffness

Fine motor control diminishes with age primarily due to:

Loss and reorganisation of motor neurones

When muscle fibres are reinnervated by surviving motor neurones, what is the typical result?

Recovery of force but reduced fine control

A motor unit is best described as:

A group of muscle fibres and their innervating neuron

Which of the following is not a direct consequence of muscle atrophy?

Increase in myofibrillar density

What is the key benefit of regular, diverse exercise as described in the lecture?

It maintains functional capacity over time

What best explains the mechanism of strength loss in ageing muscle?

Reduction in sarcomere number and crossbridges

Which component is primarily responsible for the mechanical stiffness of muscle?

Collagen-based connective tissue

What is the primary function of the muscle spindle?

To detect changes in muscle length and initiate contraction

Which sensory neuron is associated with the muscle spindle?

1a afferent neuron

What is the role of gamma motor neurons in muscle spindle function?

Maintain intrafusal fibre tension for sensitivity

What initiates the stretch reflex in the patellar tendon test?

Passive stretch of the quadriceps femoris muscle

During the stretch reflex, which muscle group is inhibited?

Antagonist muscle group

What is the function of the Golgi tendon organ in reflex activity?

Inhibit host muscle activity during high tension

What type of sensory neuron is associated with the Golgi tendon organ?

1b afferent

Where is the Golgi tendon organ located?

Near the muscle-tendon junction

What characterizes the flexor withdrawal reflex?

Polysynaptic pathway with unilateral flexion and contralateral extension

Which sensory input triggers the flexor withdrawal reflex?

Nociceptive signal from a pain receptor

What is the result of flexor withdrawal on the opposite limb?

Activation of extensors and inhibition of flexors

What is the purpose of activating the extensors in the opposite limb during the withdrawal reflex?

To maintain postural stability

What are the extrafusal fibres innervated by

Alpha Motor Neurons

What are the ends of the intrafusal fibres innervated by

Gamma motor neurons

What best describes lactose?

A disaccharide made from galactose and glucose

What structural feature distinguishes oleic acid from palmitic acid?

Presence of a double bond causing a bend

Which amino acid has the simplest side chain (R group)?

Glycine

Why must ATP be continuously regenerated in cells?

Because its availability is limited in cells

Which of the following is unique to muscle cells for ATP regeneration?

Creatine phosphate system

What is the role of creatine kinase in ATP production from creatine phosphate?

It removes a phosphate from creatine phosphate and adds it to ADP

When is creatine phosphate re-synthesized in the muscle?

During recovery or inactivity

Which enzyme catalyzes the first step of glycolysis?

Hexokinase

What is the net ATP gain from anaerobic glycolysis per molecule of glucose?

2 ATP

Which enzyme is responsible for splitting fructose 1,6-bisphosphate into two three-carbon molecules?

Aldolase

The molecule dihydroxyacetone phosphate (DHAP) is eventually converted into:

Glyceraldehyde 3-phosphate

What is the role of genetics in glycolysis?

Genes encode enzymes that catalyze each step of glycolysis

Which statement best describes the speed and efficiency of ATP production by the creatine phosphate system?

Fast and complete due to an efficient enzyme

How long can the creatine phosphate system alone provide energy to muscles?

10–15 seconds

Which of the following contributes to muscle soreness and fatigue?

Lactic acid accumulation

What is the total duration of energy that can be supplied by stored ATP, creatine phosphate, and anaerobic glycolysis together?

About 1 minute

What is the primary reason anaerobic metabolism is useful during intense, short-term activities?

It generates ATP faster than aerobic metabolism

Which intermediate is NOT produced during glycolysis?

Acetyl-CoA

What happens to lactate after it is produced in skeletal muscle?

It diffuses into blood and is used by liver, heart, and kidneys

Which structure within the mitochondrion increases surface area for ATP production?

Cristae

Where does the citric acid (Krebs) cycle take place within the mitochondrion?

Matrix

What is the correct sequence for pyruvate metabolism in aerobic respiration?

Pyruvate → Acetyl CoA → Citric acid cycle → NADH/FADH2

What is the immediate product when acetyl CoA combines with oxaloacetate?

Citrate

Which of the following is not a product of the citric acid cycle?

Pyruvate

What is the main role of the electron transport chain in the mitochondria?

To transfer electrons and pump protons for ATP synthesis

Where in the mitochondrion are the proteins of the electron transport chain located?

Inner membrane of cristae

What directly powers the ATP synthase enzyme to produce ATP?

Flow of protons through a membrane channel

What is the total ATP yield per glucose molecule via aerobic metabolism?

36–40 ATP

How do fatty acids enter the citric acid cycle?

After being converted to acetyl CoA

Which of the following statements about protein metabolism is correct?

Amino acids enter at various points in aerobic metabolism

What compound is regenerated at the end of the citric acid cycle to restart the process?

Oxaloacetate

Which of the following best explains why aerobic metabolism produces more ATP than anaerobic metabolism?

It includes both citric acid cycle and oxidative phosphorylation

What happens to NAD+ and FAD after they release electrons in the electron transport chain?

They return to the citric acid cycle to collect more electrons

Which structure ensures action potentials reach the interior of the muscle fibre?

T tubules

What receptor detects voltage change in the T tubule membrane?

Dihydropyridine (DHP) receptor

How is calcium moved back into the sarcoplasmic reticulum during relaxation?

Calcium ATPase (SERCA) pumps

Which molecule helps buffer calcium concentration inside the SR?

Calsequestrin

What allows the myosin head to detach from actin during the cross-bridge cycle?

ATP binding to the myosin head

What triggers the power stroke during muscle contraction?

Release of phosphate from the myosin head

What repositions the myosin head after detachment from actin?

Hydrolysis of ATP into ADP and phosphate

What causes the calcium channels in the SR to close during relaxation?

Repolarisation and return of DHP receptor to resting state

What maintains low intracellular sodium levels at rest in the muscle fibre?

Sodium ATPase pumps

Which of the following best describes a concentric muscle contraction?

Muscle shortens when its contractile force exceeds opposing resistance

In an eccentric contraction, which of the following is true?

Muscle is stretched as its contractile effort is less than opposing resistance

What is the primary characteristic of an isometric contraction?

Muscle length remains constant despite active force generation

During a controlled lowering of a dumbbell at the elbow, the biceps brachii is:

In an eccentric contraction, actively lengthening against gravity

Which contraction type is demonstrated when holding the knee at a fixed angle against gravity?

Isometric contraction of the biceps femoris

When stepping up, the hip and knee extensors primarily perform:

Concentric contractions to generate upward force

During stepping down, the gluteal and quadriceps muscles experience:

Eccentric contractions as they resist gravitational descent

According to the force-velocity relationship, a muscle:

Generates less force at higher shortening velocities

Which of the following correctly matches force capability with contraction type?

Eccentric – force increases with rapid but small stretches

n the combined force-velocity graph, where is the maximum active force observed?

At zero velocity, corresponding to isometric contraction

Which muscle action functions as a braking system during movement?

Eccentric contraction of extensors during limb lowering

What is the approximate safe range of muscle length change during contraction?

Approximately 10% of muscle’s resting length

Which of the following statements about eccentric contractions is correct?

Muscle generates more resistive force with rapid lengthening

When lifting a dumbbell during an elbow flexion exercise, the triceps brachii is likely:

Relaxed and passively lengthened

Which condition would result in near-zero force production?

Rapid concentric contraction at maximum shortening velocity

What type of contraction

Concentric

What type of contraction

Essentric

In the twitch myogram, which phase involves the release of calcium from the sarcoplasmic reticulum?

Latent period