Where does the circulating lymph return to cardiovascular circulation?

a. Forming the contractile component of the digestive, urinary, and reproductive systems: This describes smooth muscle, not skeletal muscle.

b. Contracting to cause involuntary muscle movements: This is a characteristic of smooth and cardiac muscles. Skeletal muscle is primarily involved in voluntary movements.

c. Pumping blood throughout the body: This is the function of cardiac muscle, not skeletal muscle.

d. Shivering for heat production: Correct. Skeletal muscles generate heat through shivering, which is an involuntary contraction response to cold.

a: Producing coagulation factors - This function is associated more with the liver, which produces various clotting factors involved in the coagulation process.

b. Destroying dying red blood cells: The spleen is primarily involved in the destruction of old or damaged red blood cells. It acts as a reservoir for blood, where it filters out old or abnormal red blood cells, recycling their components and removing any potentially harmful substances.

c: Producing leukocytes before birth - Leukocytes (white blood cells) are primarily produced in the bone marrow, not the spleen.

d: Storing glycogen - Glycogen storage is mainly associated with the liver and muscles, not the spleen.