The secondary structure of a protein refers to?

Protein's secondary structure is the three dimensional form of local pieces of proteins. Secondary structure is formally explained by the pattern of hydrogen bonds between the amino hydrogen and carboxyl oxygen atoms in the peptide backbone.

what statement best describes the difference between the sympathetic and parasympathetic nervous systems?

the sympathetic nervous system prepares the body for intense physical activity and is often referred to as the fight-or-flight response. the parasympathetic nervous system has almost the exact opposite effect and relaxes the body and inhibits or slows many high energy functions.

answer; the tunica intima also called tunica interna, consists of elastic fibers,connective tissue and smooth muscle cells;