Chapter 20

List the endocrine organs involved in producing sex differences and describe their functions.

Steroid hormones act by ________ A. causing neurons to fire; B. increasing muscle contraction; C. diffusing across membranes and regulating the expression of genes; D. binding to receptors on the cell surface and transducing a response without entering the cell

The endocrine organ that sits atop a kidney is _______ A. the pituitary gland; B. the hypothalamus; C. the ovary; D. the adrenal gland; E. the testicle

Bones of the limbs form part of the ________ A. appendicular skeleton; B. axial skeleton; C. spongy bone; D. compact bone

Osteoblasts ______ A. are found in the marrow of bone; B. regulate bone deposition; C. regulate bone reabsorption; D. are more active when calcium is low

During muscle contraction, ______ A. the actin heads pull the sarcomere closed; B. myosin attaches to actin, pulls it toward the center of the sarcomere, releases it, and reattaches further along; C. myofibrils shrink due to the actions of testosterone; D. muscle fibers contract under the actions of testosterone

Which of the following is a true statement regarding muscle contraction? A. Actin filaments are stationary, and myosin heads can move; B. Z discs are pulled toward the center of the sarcomere; C. Actin is used up during this process; D. No ATP is required for movement to occur.