The Integumentary System.pdf

HU M A N A NA T OM Y & PHYSIOLOGY I
The Integumentary System
Presented By ; Rxmaster Mind

Contents
 Introduction
 Components of the Integumentary System
 Functions of Skin

Introduction
 The integumentary system contributes to homeostasis by
protecting the body and helping regulate body temperature .
It also allows you to sense pleasurable , painful , and other
stimuli in your external environment .
 The integumentary system is composed of the skin , hair , oil
and sweat glands, nails and sensory receptors.
Dermatology ; is the medical specialty that deals with the
diagnosis and treatment of integumentary system disorders.
 The skin consists of a superficial , thin epidermis and a
deep , thicker dermis . Deep to the skin is the
subcutaneous layer.

Components of the Integumentary System
1) Epidermis – The superficial , thinner portions,
which is composed of epithelial tissue.
2) Dermis – The deeper , thicker portions , which is
composed of connective tissue.
3) Subcutaneous layer ( Hypodermis) – Deep to the
dermis but not part of the skin .

Epidermis :
The epidermis is composed of Keratinized stratified squamous epithelium .
 It consists four principal types of cells ;
I. About 8% of the epidermal cells are Melanocytes.
II. About 90% of epidermal cells are Keratinocytes .
III. Langerhans cells arise from red bone marrow and migrate to the epidermis
IV. Merkel cells are located in the deepest layer of the epidermis.
Layers of the Epidermis :
(1) Stratum Basale ; The deepest layer of the epidermis is the stratum basale
, composed of a single row of cuboidal or columnar Keratinocytes .
Stem cells – Cells that undergo cell division to continuously produce new
Keratinocytes.
The stratum basale is also known as the stratum germinativum .

(2) Stratum Spinosum – Superficial
to the stratum basale is the stratum
spinosum, arranged in 8 to 10 layers of
many – sided Keratinocytes fitting
closely together.
 Langerhans cells projects of
Melanocytes are also present in this
layer.
(3) Stratum Granulosun - At about
the middle of the epidermis , the stratum
granulosum consists of three to five layr
of flattened keratinocytes that are
undergoing apoptosis.
(4) Stratum Corneum – The stratum
corneum consists on average of 25 to 30
layers of flattened dead keratinocytes .
 Its multiple layers of dead cells also
help to protect deeper layers from injury
and microbial invasion.

Dermis ;
 The second, deeper part of the skin, the dermis .
 It composed of a strong connective tissue containing collagen and
elastic fibers.
 Blood vessels, nerves , glands and hair follicles are embedded in the
dermal .
 Papillary region consists of areolar connective tissue containing
thin collagen and fine elastic fibers .
 Reticular region which is attached to the subcutaneous layer ,
consists of dense irregular connective tissue containing fibroblasts ,
bundles of collagen and some coarse elastic fibers .
 The few cells present in the dermis include predominantly fibroblasts
, with some macrophages and a few adipocytes near its boundary with
the subcutaneous.
Dermatoglyphics ; The study of the pattern of epidermal ridges .

Subcutaneous Layer ;
 Also called the hypodermis .
 This layer consists of areolar and adipose tissues.
 The subcutaneous layer serves as a strong depot for fat and contains
large blood vessels that supply the skin . This region also contains nerve
ending called pacinian corpuscles that are sensitive to pressure.

Function of Skin
 Thermoregulation; The skin contributes to
thermoregulation in two ways ;
1.Liberating sweat at its surface and by adjusting the flow of
blood in the dermis.
2. In response to low environmental temperature,
production of sweat from eccrine sweat glands is decreased,
which helps conserve heat.
 Blood Reservoir ; The dermis houses an extensive
network of blood vessels that carry 8-10% of the total flow
in a resting adult . For this , the skin acts as a blood
reservoir.

•Protection ; The skin provides protection to the body in various ways.
 Keratin protects underlying tissues from microbes , abrasion, heat and
chemicals and the tightly interlocked Keratinocytes resist invasion by
microbes.
• Cutaneous Sensations ; Cutaneous sensations are sensations that arise
in the skin , including tactile sensations – touch , pressure , vibration, and
tickling –as well as thermal sensations such as warmth and coolness .
• Excretion and Absorption ; About 400mL of water evaporates
through it daily .
 Lipid- soluble materials do penetrate the skin these include fat-soluble
vitamins ( A, D ,E and K ) , certain drugs and the gases oxygen and carbon
dioxide.
• Synthesis of Vitamin D; Calcitriol is a hormone that aids in the
absorption of calcium in foods from the gastrointestinal tract into the
blood.
 Only a small amount of exposure to UV light ( about 10 to 15 minutes at
least twice a week ) is required for vitamins D synthesis .

The Integumentary System.pdf

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