ANAT 1010 Lecture Notes - Eponychium, Free Surface, Body Odor
INTEGUMENTARY SYSTEM (Chapter 5)
A. Introduction
The integumentary system includes the skin and its derivatives including hair,
nails, and glands.
B. Skin
1. The skin is composed of several tissues and is one of the largest organs in the
body.
2. It consists of two major layers:
i. outer, thinner layer called the epidermis
ii. inner, thicker layer called the dermis
3. Beneath the dermis is a subcutaneous layer or hypodermis which attaches the
skin to the underlying tissues and organs.
4. The epidermis has a number of important characteristics:
i. the epidermis is composed of keratinized stratified squamous
epithelium
ii. it contains four major types of cells:
a. 90% of the cells are keratinocytes, which produce
keratin
b. melanocytes, which produce the pigment melanin
c. Langerhans cells, which are involved in immune
responses
d. Merkel cells, which are believed to function in the
sensation of touch
iii. the epidermis of thin skin consists of 4 layers and thick skin 5
layers:
a. stratum basale (deepest layer), where continuous cell
division occurs which produces all the other layers
b. stratum spinosum (contains spiny shaped cells)
c. stratum granulosum (cells contain numerous granules of
keratohyaline-precursor of keratin)
d. stratum lucidum is found only in thick skin of the palms
and soles
e. stratum corneum (surface layer), composed of many
sublayers of flat, dead cells that are continuously shed and
replaced by cells from deeper strata
iv. keratinization, the accumulation of the waterproofing and
protective keratin, occurs as cells move from the deepest layer to
the surface layer
5. The dermis has several important characteristics:
i. the dermis contains two layers:
a. the outer papillary region consists of areolar connective
tissue containing fine elastic fibers, dermal papillae, and
sensory receptors
b. the inner reticular region consists of dense, irregular
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Document Summary
Introduction the integumentary system includes the skin and its derivatives including hair, nails, and glands. The skin is composed of several tissues and is one of the largest organs in the body. It consists of two major layers: i. outer, thinner layer called the epidermis ii. inner, thicker layer called the dermis 3. Beneath the dermis is a subcutaneous layer or hypodermis which attaches the skin to the underlying tissues and organs. The epidermis has a number of important characteristics: i. the epidermis is composed of keratinized stratified squamous epithelium ii. it contains four major types of cells: a. The subcutaneous layer is located below the dermis, contains connective tissue (fat tissue), nerve and blood supply 7. The functions of the skin include: i. regulation of body temperature ii. protection iii. sensation iv. excretion v. immunity vi. blood reservoir vii. synthesis of vitamin d 8. The epidermis is avascular but the dermis has a rich blood supply.
