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Ch. 9 Muscles and Muscle Tissue
Marieb - Human Anatomy & Physiology 11th Edition
Marieb, Hoehn11th EditionHuman Anatomy & PhysiologyISBN: 9780136874034Not the one you use?Change textbook
All textbooksMarieb, Hoehn 11th EditionCh. 9 Muscles and Muscle TissueProblem 8
Chapter 9, Problem 8

Characteristics of isometric contractions include all but:
a. Shortening
b. Increased muscle tension throughout the contraction phase
c. Absence of shortening
d. Used in resistance training

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1
Step 1: Understand the definition of an isometric contraction. In an isometric contraction, the muscle generates tension without changing its length, meaning there is no visible shortening or lengthening of the muscle fibers.
Step 2: Analyze each option in the context of isometric contractions. Option (a) states 'Shortening,' which contradicts the definition because isometric contractions do not involve muscle shortening.
Step 3: Consider option (b) 'Increased muscle tension throughout the contraction phase.' This is true for isometric contractions, as the muscle tension increases while the length remains constant.
Step 4: Evaluate option (c) 'Absence of shortening.' This aligns with the definition of isometric contractions, where the muscle length stays the same.
Step 5: Review option (d) 'Used in resistance training.' Isometric exercises are commonly used in resistance training to build strength without joint movement, so this is also true.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Isometric Contraction

Isometric contraction occurs when muscle tension increases but the muscle length remains constant, meaning there is no visible shortening or lengthening of the muscle during the contraction.
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Overview of Muscle Contraction

Muscle Tension During Contraction

During isometric contractions, muscle tension rises and is maintained without changing muscle length, which differs from isotonic contractions where muscle length changes while tension may vary.
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Overview of Muscle Contraction

Applications of Isometric Contractions in Training

Isometric exercises are commonly used in resistance training to improve strength and stability by holding muscles in a fixed position against resistance without movement.
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Related Practice
Textbook Question

The neurotransmitter released by somatic motor neurons is:

a. Acetylcholine

b. Acetylcholinesterase

c. Norepinephrine

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Textbook Question

The sites where the motor nerve impulse is transmitted from the nerve endings to the skeletal muscle cell membranes are the

a. neuromuscular junctions

b. sarcomeres

c. myofilaments

d. Z discs

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Textbook Question

A smooth, sustained contraction resulting from very rapid stimulation of the muscle, in which no evidence of relaxation is seen, is called:

a. A twitch

b. Temporal summation

c. Multiple motor unit summation

d. Fused tetanus

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Textbook Question

Contraction elicited by a single brief stimulus is called:

a. A twitch

b. Temporal summation

c. Multiple motor unit summation

d. Fused tetanus

Textbook Question

The ions that enter the skeletal muscle cell during the generation of an action potential are

a. Calcium ions

b. Chloride ions

c. Sodium ions

d. Potassium ions

Textbook Question

During muscle contraction, ATP is provided by:

a. a coupled reaction of creatine phosphate with ADP

b. aerobic respiration of glucose, and

c. anaerobic glycolysis.

______ (1) Which provides ATP fastest?

______  (2) Which does (do) not require that oxygen be available?

______  (3) Which provides the highest yield of ATP per glucose molecule?

______  (4) Which results in the formation of lactic acid?

______  (5) Which has carbon dioxide and water products?

______  (6) Which is most important in endurance sports?

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