Histology Quiz 3 (p 13-18)

Which one of the following is NOT a component of a myofibril?

End to end chainlike arrangement of sarcomere

Which protein forms a head at one end of each heavy chain of myosin?

Myosin light chains

What is the function of tropomyosin in muscle contraction?

To regulate actin-myosin interaction

Which type of muscle fiber is best suited for brief bursts of intense muscle activity?

Fast-twitch fibers Signup and view all the answers

What is the main structural basis for myofibrillar elasticity?

Titin Signup and view all the answers

What is the primary source of ATP generation in muscle contraction?

Glycolysis Signup and view all the answers

Which of the following is NOT a characteristic of a sarcomere in skeletal muscle?

Contains mitochondria and glycogen granules Signup and view all the answers

What is the role of the A band in a sarcomere?

Transverse alignment of links creating M-line Signup and view all the answers

What is the main component of the I band in a sarcomere?

Actin filament Signup and view all the answers

What is the function of the Z disc in a sarcomere?

Marks one end of the sarcomere Signup and view all the answers

What is the role of the M-line in a sarcomere?

Transverse alignment of links creating the H-band Signup and view all the answers

What is the function of the H zone in a sarcomere?

Elastic connection between thick filaments and Z line Signup and view all the answers

Smooth muscle cells are arranged in layers or bundles in the walls of which of the following large hollow organs?

Intestine Signup and view all the answers

What is the direction of the smooth muscle fibers in each layer?

Same in each layer Signup and view all the answers

Which staining methods can be used to visualize the reticular fibers in smooth muscle cells?

Mallory's aniline blue Signup and view all the answers

What is the role of elastic fibers in smooth muscle?

Provide structural support Signup and view all the answers

What happens to smooth muscle cells during contraction?

They shorten and become thicker Signup and view all the answers

What is the pathway of smooth muscle contraction?

Influx of calcium ions, binding to myosin light chain kinase, phosphorylation of myosin light chain, interaction with actin Signup and view all the answers

Which of the following is true about cardiac muscle cells?

Transitional myocytes contribute to the atrioventricular delay. Signup and view all the answers

What is the role of the Purkinje myocytes in the heart?

Increase in cell to cell contact Signup and view all the answers

How is the heart rate modulated by the autonomic nervous system?

Vagus nerve stimulation slows down the heart rate. Signup and view all the answers

Where are smooth muscles found in the body?

In the walls of blood vessels Signup and view all the answers

What is the shape of smooth muscle cells?

Fusiform Signup and view all the answers

What is the process of contraction in smooth muscles?

Influx of calcium ion via calmodulin Signup and view all the answers

Which of the following is true about the sliding filament mechanism of skeletal muscle contraction?

The initiation and release of Ca2+ into the sarcoplasm results in the shortening and contraction of actin filaments Signup and view all the answers

Which of the following is true about the innervation of skeletal muscle?

Acetylcholine release at the myoneural junction leads to the depolarization of the sarcolemma Signup and view all the answers

Which of the following is true about cardiac muscles?

They consist of separate cellular units joined end to end at junctional complexes Signup and view all the answers

Which of the following is true about the contraction of cardiac muscles?

The increase in calcium concentration leads to the depolarization of the sarcolemma and T-tubules Signup and view all the answers

Which of the following is true about the conduction system of the heart?

The atrioventricular node is located between the right ventricle and atrium Signup and view all the answers

Which of the following is true about the histology of cardiac muscle cells?

Cardiac muscle cells are joined end to end at junctional complexes called intercalated discs Signup and view all the answers