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 (NH3, Urea etc.) are lost through sweating.

Insignificant compared to excretory system!!!

What are the functions of the Integ. System?

2 (3) main layers:EpidermisThin layer of stratified squamous epithelium

What are the main layers of the Integ. System?

DermisThicker, tough layer of dense irregular connective tissue and other components

Technically NOT part of the skin, varies in thickness depending in part on the amount of adipose present

Hypodermis

What layer(s) of the epidermis allow this baby to have hope of “normal” face again?

Take 2!!!

Discuss with your

neighbor and predict an

answer.

• Contains all the “goodies”

• 2 layersReticular layerPapillary layer

Dermis is primarily what type of tissue?

Consists of fibroblasts and abundant protein fibers (matrix), adipose cells and macrophages

What types of fibers?

ReticularElasticCollagen

What are the Dermis Details?

Epidermis of some skin follows contours of parallel papillary ridges.

Is this in thin or thick skin?

How, where and why do we have “fingerprints”?

Tension (cleavage) lines

Striae (stretch marks)

As the skin is stretched the dermis “ruptures” and forms linear scars (striae).Let’s predict the orientation of tension lines based on the direction of striae!

Is the skin equally strong in all directions?

• Fibroblasts, adipose cells (1/2 of body fat) and macrophages•Primarily loose connective tissue

•Also called subcutaneous tissue

What are the Hypodermis Details?

Sweat glands…

• Merocrine sweat glands

• Apocrine sweat glands

Abundant & widespread, mostly H2O, ducts to surface of skin, myoepithelial cells.

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

What type of glands are in the skin?

Fig. 11.9

Growth from Matrix!

What’s all the fuzz about?

13

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 AtherosclerosisThrombosis - a clot in a blood vessel, also related to atherosclerosis Extreme cold injury (frostbite).

http://www.reversegangrene.com/A.htm

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 3rd degree (full thickness)

All layers damaged ~black, NO pain, NO blisters

Why are burns some of the most painful injuries?

Eschar

Types are identified based on the type of cells that mutate:Basal cell carcinomaLeast dangerous, start as “shiny” bump, center becomes concave and ulcerus Squamous cell carcinoma

Melanoma

Raised, red, “scaly” & ulcerus, can metastasize

Dark, flat, irregular, most deadly

Is all skin cancer equally dangerous?

20

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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The End