Next Structure and Components 5

Question 1

The lymphatic system's thoracic duct drains into which blood vessel?

Accepted Answer

Left subclavian vein

Answer

The thoracic duct empties lymph from most of the body into the left subclavian vein at the venous angle.

Question 2

Which structural feature of the small intestine dramatically increases its absorptive surface area?

Accepted Answer

Villi and microvilli

Answer

Villi and microvilli (brush border) increase the surface area of the small intestine up to 600-fold for nutrient absorption.

Question 3

The sarcomere, the basic contractile unit of skeletal muscle, is bounded by:

Accepted Answer

Z lines (Z discs)

Answer

Each sarcomere extends from one Z line (Z disc) to the next, containing overlapping actin and myosin filaments.

Question 4

Which component of a long bone contains the primary site for red blood cell production in adults?

Accepted Answer

Red marrow in epiphyses

Answer

In adults, hematopoiesis (red blood cell production) occurs in the red bone marrow found in the epiphyses of long bones and flat bones.

Question 5

The renal cortex and medulla differ in structure; the medulla contains primarily:

Accepted Answer

Loops of Henle and collecting ducts

Answer

The renal medulla is organized into pyramids containing the loops of Henle and collecting ducts that concentrate urine.

(Next) National Exit Test Practice Test