Lesson 3 - Functions of Skin
Student Performance Objectives
1. Explain three ways in which the skin can help to regulate body temperature.
2. Explain two protective functions that come about through the metabolism of melanocytes.
3. Describe 5 ways that the skin can slow down or prevent the invasion of deeper tissues
4. Explain the relationship of skin and vitamin D, and explain why D is not really
5. Explain how the skin prevents excessive loss of body fluids from its surface.
Lesson Outline - Taken as a totality, the skin functions in the following ways:
A. It is the major organ of sexual attraction (combined with the contouring of the
surface by the adipose tissue of the hypodermis).
B. Provides protection to the body from dehydration through its water-resistant surface
of keratin-filled, dead keratinocytes.
C. It helps to cool the body because it is not water-proof! Sweat glands secrete
(see lesson 4, below) continuously through ducts that penetrate through the
and the majority of this sweat passes to the surface and evaporates without being
you as accumulated moisture. This is referred to as insensible perspiration because
not sense its presence. In addition, some water can penetrate upward right through
epidermal layers and evaporate from the skin surface without having passed through
sweat gland ducts. This is also part of insensible perspiration.
D. Additional regulation body temperature occurs through the constriction or dilation
vessels thereby controlling heat radiation from the body surface, and through
adipose tissue acting as insulation to body heat loss.
E. It prevents damage from sun exposure and prevents damage from excessive vitamin
formation, through melanocyte formation and distribution of the ultraviolet-absorbing
F. It protects the body from microbial invasion through its surface that is dry (bacteria
water to thrive) and through the presence of Langerhan's cells that are part
of the immune
G. It further protects us from bacteria through sweat glandular secretion of iron-binding
molecules (bacteria require iron for their survival), lysozyme (an enzyme that
bacterial cell walls), and antibodies that coat bacterial surfaces.
H. It converts a liver-produced cholesterol derivative (7-dehydrocholesterol) into
with the assistance of absorbed ultraviolet radiation penetrating from sun exposure.
an inactive form of vitamin D, leaves the skin and travels first to the liver
and then to the
kidneys where it is converted to calcitriol - active vitamin D (that helps the
body to absorb
and utilize calcium).