Transcript The Integumentary System

The Integumentary System
Chapter 5
Introduction to the Human Body
Skin
I.
Facts about skin
A. Skin, AKA the cutaneous membrane
1. Largest organ in the body
2. Surface Area ≈ 2 m2
3. Weight ≈ 10 lbs
B. Very thin: only 0.5 – 4 mm thick
C. Dermatology
Layers
II. Skin
layers
A. Epidermis
B. Dermis
C. Subcutaneous Layer
Epidermis
III.Epidermis
A. Keratinized stratified squamous epithelium
B. 4 cell types:
1. Keratinocytes – 90% of epidermal cells; 4-5 layers
a.
Keratin
b.
Lamellar granules
2. Melanocytes – 8% of epidermal cells
a.
Melanin
b.
Transfers melanin to keratinocytes
3. Langerhans cells
4. Merkel cells (disk)
Epidermis
C.Structure of epidermis
1. Most epidermis has four strata (layers) – Thin skin
a.
Stratum basale –cuboidal or columnar keratinocytes
b.
Stratum spinosum – layers of keratinocytes with desmosomes
c.
Stratum granulosum – layers of flat keratinocytes
d.
Thin stratum corneum – 25-30 layers
SEM of Keratinocytes
Epidermis
2.Where friction is greatest the skin has five layers
a.
Stratum basale
b.
Stratum spinosum
c.
Stratum granulosum
d.
Stratum lucidum – 3-5 layers of clear, dead keratinocytes
e.
Thick stratum corneum
3.Keratinization
Layers of Skin Cells
Review of the Epidermis
•
How is thick skin different from thin skin?
•
How is keratinization related to the
structure of the epidermis?
•
Why are basal cells so important to the
skin?
•
Why is the epidermis waterproof?
Warm Up #1
More non-biological analogies:
 Keratin
 Lamellar granules
 Stratum basale
 Stratum granulosum
 Keratinization
 Merkel cells
 Langerhans cells
Skin Structure: Dermis
IV.Dermis
A. Mainly CT w/ collagen and elastin fibers
B. 2 layers:
1. Stratum papillerosum (papillary layer)
a.
Corpuscles of touch (Meissner corpuscles)
b.
Free nerve endings
Skin Structure: Dermis, cont.
2.Stratum reticulosum (reticular layer)
a.
Adipocytes, hair follicles, nerves, oil and sweat glands
b.
Striae
Subcutaneous Layer
V. Subcutaneous
layer
A. Also called the hypodermis or SubQ layer
B. Composed of areolar CT and adipose
C. Contains lamellated corpuscles (Pacinian
corpuscles)
Review of the Dermis / Hypodermis
•
Which tissues make up the dermis?
•
What are the 2 layers of the dermis?
•
What is the function of each layer?
•
Which tissues make up the hypodermis?
•
What is the function of the hypodermis?
Skin Color
VI.Skin Color: controlled by 3 pigments
A. Melanin
B. Carotene
C. Hemoglobin
Skin Color
D. Skin color differences
1. Freckles
2. Age Spots
3. Albanism
Accessory Organs: Hair
VII.Accessory Organs
A.Hair (pili)
1.Threads of fused, dead, keratinized cells
2.3 main parts:
a.Shaft
b.Root
c.Follicle
Accessory Organs: Hair
3.Arrector pili
4.Color controlled by melanin
5.Present in most skin surfaces
6.Androgenic alopecia
Accessory Organs: Glands
B.Glands
1. Sebaceous
2. Sudoriferous
a.
Eccrine
b.
Apocrine
3. Ceruminous
Gland Review
Which gland…
1. Is responsible for body odor (B.O.)?
2. Protects your ears from infection?
3. Keeps you cool?
4. Keeps your hair from becoming dry and
brittle?
5. Is found on the palms of your hands?
6. Is very active on your face during puberty?
7. Is not active until puberty?
Accessory Organs: Nails
C.Nails
1. Plates of tightly packed, hard, keratinized cells of
the epidermis
2. Parts:
a.
Nail body
b.
Lunula
c.
Cuticle
d.
Free edge
e.
Nail root
f.
Nail matrix
Functions of the Skin
VIII.Functions
A. Protection underlying tissue
B. Regulation & excretion of fluid
C. Regulation of temperature
D. Synthesis of vitamin D
E. Cutaneous sensation reception
F. Communication
G. Immunity
Skin Conditions
IX. Skin Conditions
A. Skin Cancer
B. Acne
C. Nevus
D. Warts
E. Skin & Aging