Integumentary
System
KAYLEE AND JAZZY
Key Terms
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Apocrine Sweat Glands:
Glands that open into hair
follicles
Arrector Pili: a bundle of
smooth muscle cells
attached to each hair
follicle
Eponychium: the cuticle of
the fingernail
Hair Shaft: Upper layer of
dermis
Hypodermis: the
subcutaneous layer
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Keratin: tough, water
repellant protein in
epidermis
Melanocytes: Cells that
produce a dark pigment
called melanin
Papillary layer: the visible
portion of the hair
Stratum Basale: mitotic skin
layer of the epidermis
Stratum corneum: the
outermost layer of the skin
What is it?

It provides a barrier against hazardous materials and pathogens

The skin and the glands, hair, nails, and other structures make up the
system
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Since the skin is on the outside of the body, this system is exposed to
abuse in the form of bumps, cuts, scrapes, toxic chemicals,
pollutants, wind, and sun.
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The skin quickly repairs itself and continues to perform many
functions
Structure of the Skin
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Often called the cutaneous membrane
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Consists of two distinct layers of tissues
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The outer layer is called the epidermis
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The inner layer is called the dermis
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These are anchored to the underlying third layer called the
subcutaneous tissue
Epidermis
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The outer layer of the skin
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No blood vessels
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Cells receive nutrients from vessels in the underlying tissue
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Cells on the bottom actively grow and divide from receiving
adequate nutrients
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As cells are pushed upward they receive less nutrients
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By the time cells reach the top they are dead from lack of nutrients
Epidermis cont.
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Stratum basale is the bottom layer, it is closest to the blood supply
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Stratum spinosum is the next layer, it consists of several layers of cells
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Stratum granulosum is a thin region that consists of 2 or 3 layers of
flattened cells
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Stratum lucidum consists of a few layers of flattened, anucleate
cells. This region only appears in thick skin
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Stratum corneum is the surface region, it consists of 20-30 layers of
flattened, dead, completely keratinized cells
Dermis
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Dense connective tissue that is deeper and thicker than the epidermis
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Hair, nails, and certain glands are embedded in the dermis
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Contains both collagenous and elastic fibers to give it strength and elasticity
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If the skin is overstretched it could damage the dermis and leave whit scars
called striae or “stretch marks”
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Dermis is divided into 2 distinct layers called the papillary layer and the reticular
layer
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Papillary layer is the basis of finger prints and foot prints
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Reticular layer is the deeper layer of the dermis that provides strength to the skin
Skin Color
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Skin color is due to factors some genetic, some physiologic, and
some environmental
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Basic skin color is due to the dark pigment melanin produced by the
melanocytes
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Everyone has about the same number of melanocytes
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The activity of melanocytes is genetically controlled
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A larger number of melanin granules results in darker skin, a smaller
amount of melanin granules results in lighter skin
Skin color cont.
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Many genes are responsible for skin color
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A single mutation can result in the inability to produce melanin
which results in a condition called albinism
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Albinism is when an individual have very light skin, white hair, and
unpigmented irises in the eyes
Hair and Hair Follicles
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Hair is found on almost all body surfaces
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Hair is not found on the palms of the hands, soles of the feet, lips,
nipples, certain external genitalia, and distal segments of the fingers
and toes
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All hair consists of a shaft and a root that are composed of dead
cells
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The shaft of a hair is the portion that extends beyond the epidermis
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The shaft contains no nerves, therefore it can be cut with no feeling
of pain
Hair and Hair follicles cont.
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The root is the portion of hair that is below the surface of the skin
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The shaft and root both make up the hair, which is produced by a
hair follicle
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The central core of the hair is the medulla
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The root of a hair is enclosed in a tubular hair follicle
Nails
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Thin plates of dead stratum corneum that contain a very hard type
of keratin and cover the dorsal surfaces of the distal ends of the
fingers and toes
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Each nail has a free edge, nail body, and a nail root
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The cuticle is a fold of stratum corneum that grows onto a portion of
the nail body
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Stratum basale grows under the nail body to form a nail bed
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The nail matrix is responsible for nail growth
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Nails appear pink because of the rich supply blood vessels in the
underlying dermis
Glands: The two major glands associated with the skin are the
sebaceous glands and the sweat glands
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Sebaceous glands
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Sweat glands
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generally associated with hair follicles
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found in all areas of body with hair
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Sebum- an oily secretion on the surface
of the skin
Widely distributed around the body
except for lips, nipples, and parts of
external genitalia
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Sebum keeps hair and skin soft and
pliable
There are more sweat glands in the palms
and soles
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An individual as about 2.5 mil. sweat
glands
Recall
1.
Cells that produce a dark pigment
A.
Apocrine sweat glands
2.
Outermost layer of the skin
B.
Arrector pili
3.
Actively mitotic layer of the
epidermis
C.
Eponychium
D.
Hair Shaft
E.
Hypodermis
F.
Keratin
G.
Melanocytes
H.
Papillary layer
I.
Stratum basale
J.
Stratum corneum
4.
Subcutaneous layer
5.
Visible portion of hair
6.
Cuticle of fingernail
7.
Glands that open into hair follicles
8.
Muscle attatched to hair follicles
9.
Tough, water repellant protein in
epidermis
10.
Upper layer of epidermis
Answers
1.
Cells that produce a dark pigment
A. Melanocytes
2.
Outermost layer of the skin
B. Stratum Corneum
3.
Actively mitotic layer of the epidermis
C. Stratum Basale
4.
Subcutaneous layer
D. Hypodermis
5.
Visible portion of hair
E. Papillary layer
6.
Cuticle of fingernail
F. Eponychium
7.
Glands that open into hair follicles
G. Apocrine sweat glands
8.
Muscle attatched to hair follicles
H. Arrector pili
9.
Tough, water repellant protein in epidermis
I. Keratin
10.
Upper layer of epidermis
J. Hair shaft