Surface membrane barriers such as skin and mucous membranes are part of our 1st line of defense. Name 4 ways the skin protects us:
a) Physical barrier, chemical barrier, microbiological barrier, immune surveillance
b) Hormonal regulation, temperature control, nutrient absorption, waste elimination
c) Muscle contraction, sensory perception, wound healing, excretion
d) Gas exchange, nutrient transport, cellular respiration, toxin removal