Question

Larger T-tubules (in lumen size)

Intercalated disks

Troponin

Slow, L-type Ca channels

Reduced amount of SR

Sarcomeres

a) 1, 2, 3, 4, 5, 6
b) 2, 4, 6
c) 3, 5, 1
d) 4, 6, 2

Answer 1

The question involves identifying features of cardiac muscle tissue, such as sarcomeres for contraction, T-tubules for electrical impulse conduction, and intercalated disks for cell connection, as well as the role of troponin and calcium channels in muscle contraction.

Step-by-step explanation:

The student's question is pertaining to the structures and characteristics of cardiac muscle tissue and their functions. Cardiac muscle cells, also known as cardiomyocytes, are specialized muscle cells found in the heart. They are composed of myofibrils arranged in sarcomeres, which are the contractile units of the muscles. To facilitate the rapid conduction of electrical impulses necessary for synchronized contractions, cardiac muscles have T-tubules and are connected to each other by intercalated disks that contain gap junctions allowing for an electrical connection between the cells. Troponin is a protein complex involved in muscle contraction. It binds to calcium ions that enter from slow, L-type Ca channels and initiates the contraction process. Cardiac muscle contains a reduced amount of sarcoplasmic reticulum (SR) compared to skeletal muscle, and thus relies more on extracellular calcium for initiating contractions.