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Biology 211 Anatomy

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Biology 211 Anatomy & Physiology I Integumentary System – PowerPoint PPT presentation

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Title: Biology 211 Anatomy


1
Biology 211Anatomy Physiology I
Integumentary System
2
The Integumentary System
  • Skin Integument
  • Largest organ in body 15 of body weight
  • Skin accessory organs
  • (hair, nails, glands)

Integumentary system
3
Functions of Integumentary System (skin its
products)
Barrier to keep water and solutes in Barrier to
keep bacterial, dirt, etc. out Protection against
abrasion Contains sensory receptors for touch,
temperature, pressure, pain, etc. Temperature
regulation via hair, sweat, amount of blood
flow Blood reservoir Synthesis of vitamin
D Excretion
4
Three Layers of skin
Epidermis Stratified squamous epithelium
outer layer is "keratinized" or
"cornified" Dermis Dense irregular connective
tissue Hypodermis Adipose connective tissue
5
Epidermis Avascular.
Depends on blood vessels in underlying
dermis for its nutrition
Cells formed by mitosis in deepest, or basal,
layer, then get pushed into more superficial
layers or "stata"
6
(Epidermis)
Stratum Basale Single row of dividing
cells Stratum Spinosum Three or four layers
of cells
Some cell division Stratum Granulosum Three
or four layers of cells
Actively synthesizing protein

keratin Stratum Lucidum One or two layers of
dying cells Stratum Corneum Many layers of
flat, dead, scale-like
cells full of keratin
7
(Epidermis)
Keratinocytes move from stratum basale to stratum
corneum, dying as they do so. Average 4 - 6
wks
- Keratinocytes in stratum basale ( stratum
spinosum) lie along basement membrane
divide by mitosis
- Older ones pushed toward surface by newer cells
- Melanocytes transfer melanin to keratinocytes
- Keratinocytes synthesize large amounts of
keratin and flatten out as they move toward
surface
- Older cells die but remain attached to each
other
- Cells eventually shed from stratum corneum
8
Primary cell type in epidermis keratinocytes
which produce large amounts of protein keratin
Other cell types Melanocytes produce pigment
melanin transfer it to keratinocytes Dendritic
or Langerhans cells (immune cells) protect
against toxins pathogens Tactile or
Merkel cells detect touch and pressure transfer
this information to sensory receptors in the
dermis
9
Skin Color
Most significant factor is melanin 2 forms
eumelanin (brownish black)
pheomelanin (reddish yellow) Melanin
produced by melanocytes
accumulates in keratinocytes Different races
similar numbers of melanocytes,
different amounts of melanin produced
Also Carotene yellow Hemoglobin in blood
red/pink
10
Dermis
Dense irregular connective tissue Separated from
epidermis (stratified squamous epithelium) by
basement membrane Highly vascular Highly
innervated
Two Layers Papillary layer just below
epidermis Reticular layer forms deep 80
11
Dermis
Contains many types of sensory receptors for
touch, pressure, vibration, pain, temperature,
etc.
Some simple nerve endings Others complex
structures with multiple cell types
12
Dermis Dense irregular connective tissue. Thus
Cells Fibroblasts / Fibrocytes
Macrophages Mast cells
Lymphocytes etc. Fibers
Collagen (strength) Elastic
(stretchable)
13
Appendages of the skin
Hair follicles and hair Sweat glands Sebaceous
(oil) glands Nails on fingers and toes
All begin as epidermis of embryo grow down into
dermis
14
Hair Distributed over all skin except
palms of hands
soles of feet
nipples

glans of penis clitoris
minor
labia Minimal trunk limb hair Thicker on
scalp to retain heat Eyebrows enhance facial
features, shade eyes Nostril hair filters dust
other particulates Pubic hair, axillary hair,
anal hair retain pheromones
15
Hair
Formed in follicles in dermis
Consists of layers of
dead,
highly keratinized keratinocytes
Vellus hair is finer. Covers arms, legs, back,
chest, etc. Terminal hair is longer and
courser. Scalp, pubic hair,
axillary hair, eyelashes, eyebrows,
male facial hair
16
Shaft
Root
Bulb
17
Medulla Loosely arranged keratinocytes
Thickest in terminal hair absent in
vellus hair Cortex Densely packed
keratinocytes Cuticle Keratinocytes loosely
arranged like scales
18
Black or brown color due to eumelanin produced by
melanocytes and transferred to keratinocytes in
follicle. Red color produced by pigments
called pheomelanin Blonde color produced by
intermediate levels of pheomelanin and low levels
of eumelanin
The same gene that produces pheomelanin also
increases the number of freckles on the skin, so
redheads often have more freckles.
19
Texture of hair is due to the shape of the hair
shaft. The rounder the hair shaft, the
straighter it will be The flatter the hair
shaft, the more curled it will be
20
Each hair is associated with One or more
sebacious (oil) glands An arrector pili muscle
(smooth muscle) A plexus of nerves
around the root
21
Sweat Glands - 2 to 3 million Two
types Merocrine Distributed over all skin
except nipples (Eccrine) Simple coiled glands
in dermis Duct leads to sweat
pore on surface Secrete watery
sweat for cooling Apocrine Located only
in axillary, pubic, anal regions
Larger than eccrine glands Duct
opens into opening of hair follicle
Thicker sweat, high content of protein and
fats Contains scent molecules
sexual, fear, etc.
22
Sweat is usually 99 water with a pH between 4
and 6 Contains significant amounts of sodium,
potassium, calcium, chloride, and trace amounts
of other minerals 500 ml/day at rest, more
at warmer temperatures 2,000 ml/hour
during moderate to intense exercise
23
Modified Sweat Glands
Ceruminous glands in external ear canal.
Secretion combines with sebum to form earwax
Mammary glands in breast
24
Sebaceous (oil) glands - Branched tubular
glands - Duct opens into opening of hair
follicle - Most common on face scalp -
Secretes sebum consisting of lipids,
proteins, ions, carbohydrates to protect the
skin and hair

25
Nails - Tips of fingers and toes - Thick
layer of densely packed keratinocytes -
Produced by nail matrix at proximal end,
hidden under eponychium or cuticle
Deeper layers of epidermis nail bed
Average growth 0.5 mm per week
26
Burns
Major cause of accidental death Classified by
depth of tissue involvement Superficial
involves epidermis only Partial thickness
involves epidermis
and some dermis Full thickness
epidermis, dermis,
and deeper tissue
destroyed
27
Carcinomas (cancers) of the skin
Basal Cell Carcinoma Keratinocytes of
stratum basale proliferate, invade
dermis Relatively low malignancy
Squamous Cell Carcinoma Keratinocytes of
epidermis proliferate May or may not invade
dermis Moderate malignancy
Malignant Melanoma Melanocytes of epidermis
proliferate and invade dermis
Highly malignant
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