TEAS 7 ExamC++TEAS 7 Science Practice Test X5BoostWhich of the following describes one difference between skeletal muscles and cardiac musclesCurrent
Which of the following describes one difference between skeletal muscles and cardiac muscles?
A.
Skeletal muscles are found in the viscera whereas cardiac muscles are found in the cranium
B.
Cardiac muscles contain intercalated discs, whereas skeletal muscles do not
C.
Cardiac muscles are voluntary, whereas skeletal muscles are involuntary
D.
Skeletal muscles are autorhythmic, whereas cardiac muscles are not
The correct answer and Explanation is :
The correct answer is B. Cardiac muscles contain intercalated discs, whereas skeletal muscles do not.
Explanation:
Cardiac and skeletal muscles are both types of striated muscles, meaning they have a banded appearance under a microscope due to the arrangement of their contractile proteins. Despite this similarity, they have distinct structural and functional differences that are crucial for their roles in the body.
- Intercalated Discs: One of the most notable differences between cardiac and skeletal muscles is the presence of intercalated discs in cardiac muscle. These discs are specialized structures that connect individual cardiac muscle cells (cardiomyocytes) to one another. They contain gap junctions and desmosomes, which facilitate the rapid transmission of electrical impulses between cells and provide mechanical strength to the tissue. This connectivity is essential for the synchronized contraction of the heart, allowing it to function as a unified pump. Skeletal muscle cells, on the other hand, do not have intercalated discs. Instead, they are connected by a different type of cell junction called the neuromuscular junction, which is involved in transmitting signals from motor neurons to the muscle fibers.
- Muscle Function and Control: Cardiac muscles are involuntary, meaning their contraction is not consciously controlled; it is regulated by the autonomic nervous system and intrinsic pacemaker cells in the heart that set the rhythm of the heartbeat. Skeletal muscles, in contrast, are typically voluntary and are controlled by the somatic nervous system, allowing for conscious movement and fine motor control.
- Location and Function: Skeletal muscles are primarily attached to bones and are responsible for voluntary movements of the body, including locomotion and manipulation of the environment. Cardiac muscles are found only in the heart and are responsible for pumping blood throughout the circulatory system.
- Autorhythmicity: Cardiac muscles have the unique ability to generate their own rhythmic contractions without external stimuli, thanks to specialized pacemaker cells. Skeletal muscles do not possess this property and require neural stimulation to initiate contraction.
Understanding these differences helps in comprehending how the muscular system functions to maintain various physiological processes essential for life.