Which is a physiological description rather than an anatomical one

1. Which is a physiological description rather than an anatomical one?
   a. There are fenestrations (openings) in the epithelial cells of capillary walls
   b. The walls of blood capillaries are composed of a thin epithelium.
   c. The muscles of the thigh are composed of skeletal muscle tissue.
   d . The muscles of the intestinal wall contract slowly and involuntarily.
2. A term that means “toward the attached end of a limb is
   a. lateral
   b. superficial
   c . proximal
   d .distal
3. During skeletal muscle contraction
   a. thin filaments slide across thick filaments
   b. myosin heads interact with tropomyosin
   c the H band increases in size
   d.Ca2+ associates with tropomyosin

The Correct Answer and Explanation is :

1. Which is a physiological description rather than an anatomical one?

Answer: d. The muscles of the intestinal wall contract slowly and involuntarily.

• Explanation:
  Anatomical descriptions focus on the physical structure of the body and its parts, whereas physiological descriptions focus on the functions and processes.
• Option a (There are fenestrations in the epithelial cells of capillary walls) is an anatomical description, as it refers to the structure of capillary walls.
• Option b (The walls of blood capillaries are composed of a thin epithelium) is an anatomical description, as it describes the tissue structure of capillaries.
• Option c (The muscles of the thigh are composed of skeletal muscle tissue) is anatomical because it describes the composition of the thigh muscles.
• Option d describes a function of the muscles of the intestinal wall, specifically the process of contraction, which is physiological. It mentions the action (contracting slowly and involuntarily), which is a functional aspect of the muscle rather than its structure.

2. A term that means “toward the attached end of a limb is

Answer: c. proximal

• Explanation:
• Proximal refers to being closer to the point of attachment of a limb or the trunk of the body. For example, the shoulder is proximal to the wrist.
• Distal means farther from the point of attachment. For example, the wrist is distal to the elbow.
• Lateral refers to being farther from the midline of the body.
• Superficial refers to being closer to the surface of the body.

3. During skeletal muscle contraction

Answer: a. thin filaments slide across thick filaments

• Explanation:
• During skeletal muscle contraction, the interaction between actin (thin filaments) and myosin (thick filaments) leads to muscle shortening. Myosin heads form cross-bridges with actin filaments and slide the thin filaments over the thick filaments, causing the sarcomere to shorten and the muscle to contract.
• Option b (myosin heads interact with tropomyosin) is incorrect because tropomyosin covers the binding sites on actin and must be moved by calcium ions (through troponin) for contraction to occur.
• Option c (the H band increases in size) is incorrect because during contraction, the H band (the region containing only thick filaments) decreases in size.
• Option d (Ca2+ associates with tropomyosin) is partially correct, but it’s not the direct mechanism of muscle contraction. Calcium ions bind to troponin, not tropomyosin, causing a conformational change that moves tropomyosin and exposes the binding sites for myosin on actin.