Tag: muscle contraction and its effects

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Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

Prolonged activation of striated muscle causes it to fatigue. What is the reason?

  1. Breakdown of glycogen into lactic acid in muscle during aerobic respiration

  2. Breakdown of lactic acid in muscle during anaerobic respiration

  3. Breakdown of lactic acid into glycogen during anaerobic respiration

  4. Produce ethanol in muscle
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • Generally, the glucose undergoes metabolism in the presence of oxygen to form ATP (adenosine triphosphate) which is essential for the muscle contraction but during vigorous exercise, the body cannot meet the oxygen demand and the glucose undergoes metabolism in the absence of oxygen (anaerobic respiration)which results in the formation and accumulation of lactic acid. The breakdown of lactic acid in muscle causes the muscle to fatigue.
  • Hence prolonged activation of striated muscle causes it to fatigue because of breakdown of lactic acid in muscle during anaerobic respiration.
  • So, the correct answer is 'Breakdown of lactic acid in muscle during anaerobic respiration'.
Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

Lactic acid causes fatigue in muscles due to

  1. Sensitivity of neuromuscular junction

  2. Acidity

  3. Binding of muscle calcium

  4. Causing expulsion of cations
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

  • Lactic acid is formed and accumulated in the muscle under conditions of high energy demand, rapid fluctuations of the energy requirement and insufficient supply of O2.
  •  During exercise, there is a progressive reduction in the ability to produce muscle forces processes within the nervous system, as well as within the muscles contribute to this fatigue. 
  •  Finally, the small-diameter muscle afferents that increase firing with exercise and fatigue. Hence, Lactic acid causes fatigue in muscles due to the Sensitivity of neuromuscular junction.
 So, the correct answer is 'Sensitivity of neuromuscular junction'.

Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

When a threshold stimulus is applied to a muscle, the muscle fibres will contract fully or will not contract at all. This is known as:

  1. Sliding filament theory

  2. All or none principle

  3. Maximal oxygen uptake

  4. Contraction period
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The all or none law states that the strength by which a nerve or muscle fiber responds to a stimulus that is independent of the strength of the stimulus. If that stimulus exceeds the threshold potential, the nerve or muscle fiber will give a complete response, otherwise, there is no response.
So, the correct option is 'All or none principle'.
Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

State whether the following statements are true or false.
A drop in the force of contraction after prolonged stimulation is known as muscle fatigue.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

  • Myofibril activity is required for muscle contraction on the molecular level. 
  • When ATP binds to myosin, it separates from the actin of the myofibril, which causes a contraction.
  • The muscle contraction cycle is triggered by calcium ions binding to the protein complex troponin, exposing the active-binding sites on the actin.
  • ATP then binds to myosin, moving the myosin to its high-energy state, releasing the myosin head from the actin active site.
  • When ATP is exhausted resulting in fatigue, lactic acid is produced 
So, the correct option is 'True'.

Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects
Though vertebrates are aerobes, their .....(i)..... show anaerobic respiration during ......(ii)..... During this, ......(iii)...... of skeletal muscle fibers is broken down to release lactic acid and energy. Lactic acid, if accumulates causes muscle fatigue.
Fill up the blanks in the above paragraph and select the correct option.

  1. i- Skeletal muscles ; ii-heavy exercise ; iii-glucose

  2. i- Skeletal muscles ; ii-mild exercise ; iii-glycogen

  3. i- Skeletal muscles; ii-heavy exercise ; iii-glycogen

  4. i- Cardiac muscles; ii-heavy exercise ; iii-glycogen
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Muscle fatigue is the reduction in force of contraction of a muscle after prolonged stimulation. In the absence of oxygen, skeletal muscle of human beings can contract for a short time, but it gets fatigued soon. This is due to the fact that in the absence of oxygen, products of glycolysis mainly lactic acid is not disposed of and accumulates in the muscles. This leads to muscle fatigue and pain in the muscles. A muscle gets fatigued sooner after a strenuous exercise than after a mild exercise. Faster breathing for sometime after a strenuous exercise supplies extra oxygen disposes off excess lactic acid and muscle fatigue disappears.

So the correct option is 'i-Skeletal muscles ; ii-heavy exercise ; iii-glucose'.

Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects
Select the incorrectly matched pair.
  1. End products of alcoholic - Ethanol + ${CO} _{2}$
  2. End products of lactic acid fermentation - Lactic acid + ${CO} _{2}$

  3. Glycolysis - Cytoplasm

  4. Key product of glycolysis - Pyruvic acid
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Lactic acid fermentation occurs in lactic acid bacteria (e.g., Lactobacillus), some fungi and muscles. In lactic acid fermentation, pyruvic acid produced in glycolysis is directly reduced by NADH to form lactic acid. No ${CO} _{2}$ is produced. The enzyme is lactate dehydrogenase which requires FMN and ${Zn}^{2+}$.

$Pyruvic \,\,acid+NADH\xrightarrow[FMN,{Zn}^{2+}]{Lactate \,\,denydrogenase}Lactic \,\,acid+{NAD}^{+}$

So the correct answer is 'End products of lactic acid fermentation - Lactic acid + ${CO} _{2}$'.
Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

In which of the following situation we have to use R.I.C.E. remedy?

  1. Frcature

  2. Sunstroke

  3. Contusion

  4. Epilepsy
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

RICE-Rest, Ice, Compression, Elevation. As soon after an injury like an ankle sprain, fracture pain can be relived with RICE. Rest and protect the area of injury.

Apply some ice to limit inflammation and pain.
Compression-Wrapping the injured area with bandage Elevation.
So the correct option is 'Fracture'. 

Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

The main cause for muscle fatigue 

  1. Acetic acid

  2. Water

  3. Lactic acid

  4. Hydro chloric acid
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Intracellular acidosis due mainly to lactic acid accumulation has been regarded as the most important cause of skeletal muscle fatigue. Inorganic phosphate, which increases during fatigue due to the breakdown of creatine phosphate appears to be a major cause of muscle fatigue.

So, the correct option is 'Lactic acid'.

Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

Which of the following is not true about rigor mortis?

  1. It is irreversible.

  2. It is not a permanent contraction.

  3. ATP increases in muscles.

  4. Time of onset is not same in all muscles.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Rigor mortis is the state of rigidity that develops in the muscles after death. It is used to determine or estimate the time of death. This refers to the stiffening of the body after death due to loss of Adenosine Triphosphate (ATP) from the body's muscles. ATP provides the energy to the muscles which help them to work and without this, the muscles become stiff and inflexible. 

Multiple choice zoology skeleton and movements features of a muscle muscle features muscle contraction and its effects

The longest phase in a single muscle twitch in a vertebrate is about 50 millisec and is ................. phase.

  1. Latent

  2. Contraction

  3. Relaxation

  4. All are equal
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Muscle twitch is the response of a muscle to a single electrical stimulation. It is divided into three phases: latent period - time between stimulation and beginning of shortening, contraction phase - time of shortening, relaxation phase- time when muscle is returning to resting length (longest phase).