What is an example of mechanical digestion?

A. To ensure that the uterus is securely connected to the supporting ligaments: This is not the primary function of the middle layer (myometrium); rather, the supporting ligaments provide stability to the uterus.

B. To allow the uterus to shed tissue during menstruation: This is primarily the function of the endometrium, the inner layer of the uterine wall.

C. To allow the uterus to contract during childbirth to expel the fetus: The middle layer, known as the myometrium, is composed of smooth muscle that contracts during labor to help expel the fetus.

D. To provide the uterus with adequate space to grow a fetus: While the uterine structure allows for fetal growth, the myometrium’s primary role is in contractions rather than providing space.

A. Lysozyme within tears destroy bacteria.: Lysozyme is an enzyme found in tears that helps to break down the cell walls of bacteria, acting as a chemical barrier and part of the innate immune system's first line of defense.

B. Chemotaxis attracts phagocytes to the site where the pathogen invaded.: This is part of the inflammatory response, which occurs after the first line of defense has been breached; therefore, it is not considered a first line of defense action.

C. Natural killer cells are the first lymphocytes to react to infection.: While natural killer cells play an essential role in the immune response, they are part of the second line of defense and respond after pathogens have entered the body.

D. Phagocytes ingest microbes when they enter the body.: This is part of the second line of defense, as phagocytes respond to pathogens that have breached the first line of defense, which includes physical and chemical barriers.