Question

question 28 1 pts skeletal muscles constitute approximately ____ of our body weight. 10% 25% 50% 75% question 29 1 pts which of the following statements about the muscles of the thorax is incorrect? when the diaphragm contracts, it decreases the volume of the thoracic cavity and expels air from the lungs. the muscles of the thorax assist in respiration. the internal and external intercostal muscles have opposite effects on the ribs. all of the above statements are correct. question 30 1 pts which of the following body systems assists the muscles in maintaining posture? digestive endocrine excretory all of the above

Explanation:

• Question 28: Skeletal muscles make up about 50% of body - weight. This is a well - known fact in human anatomy.
• Question 29: When the diaphragm contracts, it increases the volume of the thoracic cavity and draws air into the lungs, not decreases the volume and expels air. The other statements about thoracic muscles are correct.
• Question 30: The endocrine system can influence muscle function and metabolism related to posture, while the digestive and excretory systems are not directly involved in assisting muscles in maintaining posture.

Answer:

• Question 28: C. 50%
• Question 29: A. When the diaphragm contracts, it decreases the volume of the thoracic cavity and expels air from the lungs.
• Question 30: B. Endocrine