What are the functions of the Integ. System ?
Sensation:
Sensory receptors in dermis and hypodermis allow us to sense…
• touch & pressure
• pain
• heat / cold
We’ll discuss these in detail later…

What are the functions of the Integ. System ?
Excretion:
Small amounts of nitrogenous waste products (NH
3
, Urea etc.) are lost through sweating.
Insignificant compared to excretory system!!!

What are the main layers of the Integ. System ?
2 (3) main layers:
Epidermis
Thin layer of stratified squamous epithelium
Dermis
Thicker, tough layer of dense irregular connective tissue and other components
Hypodermis Technically NOT part of the skin, varies in thickness depending in part on the amount of adipose present

Take 2!!!
What layer(s) of the epidermis allow this baby to have hope of “normal” face again ?
Discuss with your neighbor and predict an answer.

What are the Dermis Details ?
• Contains all the
“goodies”
• 2 layers
Reticular layer
Pap illary layer
Dermis is primarily what type of tissue ?
What types of fibers ?
Consists of fibroblasts and abundant protein fibers
Reticular
(matrix), adipose cells and
Elastic macrophages
Collagen

How, where and why do we have “fingerprints” ?
Epidermis of some skin follows contours of parallel papillary ridges.
Is this in thin or thick skin ?

Is the skin equally strong in all directions ?
Tension (cleavage) lines
Striae (stretch marks)
As the skin is stretched the dermis “ruptures” and forms linear scars of tension lines based on the direction of striae !

What are the Hypodermis Details ?
• Fibroblasts, adipose cells (1/2 of body fat) and macrophages
•Primarily loose connective tissue
•Also called subcutaneous tissue

What type of glands are in the skin ?
Sweat glands …
• Merocrine sweat glands
Abundant & widespread, mostly H
2
O, ducts to surface of skin, myoepithelial cells.
• Apocrine sweat glands
Less abundant, found in axillary, anal, pubic regions (& faces of men), > conc. Of fatty acids, bacteria breakdown cause rancid smell, ducts to hair follicles.

What type of glands are in the skin ?
Sebaceous glands …
Secrete sebum (oily substance) often into hair follicle (holocrine glands see pg. 113).
Other glands…
Ceruminous
Mammary

Fig. 11.9

What’s all the fuzz about ?
Growth from Matrix!

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Fig. 11.B

How do you explain Deed’s foot ?
What would cause that color ?
Is the lack of sensation a symptom you would attribute to that color ?
Why or why not ?
What parts of the scene are “fakey” ?

What is the reality ?
Developing gangrene risks:
Chronic lack of sufficient blood flow!
Conditions causing this:
Diabetes
Atherosclerosis
Thrombosis - a clot in a blood vessel, also related to atherosclerosis
Extreme cold injury
(frostbite).
http://www.reversegangrene.com/A.htm

Why are burns some of the most painful injuries ?
Burns are ranked based on the severity and the depth of tissue destruction.
1st degree:
Epithelium damaged ~ red & painful, NO blisters
2nd degree:
Epithelium & some dermis damaged ~ red, white or tan, very painful, BLISTERS present
Eschar
3rd degree (full thickness)
All layers damaged ~ black, NO pain, NO blisters

Is all skin cancer equally dangerous ?
Types are identified based on the type of cells that mutate:
Basal cell carcinoma
Least dangerous, start as “shiny” bump, center becomes concave and ulcerus
Squamous cell carcinoma
Raised, red, “scaly” & ulcerus, can metastasize
Melanoma
Dark, flat, irregular, most deadly

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Fig. 11.A

21
Fig. 11.8

LEARNING OUTCOMES
11.4 Integumentary System
*Identify the two main regions of skin , and how these are distinguished from the subcutaneous layer.
*Describe the makeup and function of the accessory structures of human skin.
*List some common disorders of human skin , and how these may be treated.

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