What is the primary function of red blood cells in the circulatory system?

A. To increase blood glucose levels directly:The hypothalamus does not directly raise blood glucose; it regulates hormones that influence this process indirectly via other glands.
B. To store and release oxytocin:Oxytocin is stored and released by the posterior pituitary, not the hypothalamus itself.
C. To secrete corticotropin-releasing hormone (CRH):The hypothalamus produces and releases CRH, which stimulates the anterior pituitary to secrete ACTH, initiating the HPA axis cascade leading to cortisol release.
D. To produce aldosterone:Aldosterone is a mineralocorticoid hormone produced by the adrenal cortex, not by the hypothalamus.

A. Filtering lymph and housing lymphocytes:Lymph nodes filter lymph fluid to remove pathogens and debris and contain lymphocytes (B and T cells) and antigen-presenting cells that participate in immune responses.
B. Producing red blood cells:Red blood cell production occurs primarily in the bone marrow, not in lymph nodes.
C. Facilitating nutrient absorption:Nutrient absorption (notably fat absorption) occurs in the small intestine, particularly the villi and lacteals, rather than in lymph nodes.
D. Transporting oxygen:Oxygen transport is performed by red blood cells in the bloodstream, not by lymph nodes.