Chapter 5
Lecture Presentation by Lee Ann Frederick University of Texas at Arlington (heavily modified by GJC)
© 2015 Pearson Education, Inc. 1 The Integumentary System: beware of detail overload!
© 2015 Pearson Education, Inc. 2 The Integumentary System: my priorities
• Epidermis vs. dermis vs. hypodermis • Top of epidermis vs. bottom • Keratinocytes vs. melanocytes
• Vitamin D3 • Briefly: hair, exocrine glands (sebaceous/sweat) • Response to injury: inflammation, then . . . • Clinical applications: liposuction, burns, aging
© 2015 Pearson Education, Inc. 3 What is the integumentary system? = Epidermis + Dermis
Hair shaft Epidermis Papillary layer Touch receptors Dermis areolar Tactile (Meissner’s) corpuscle Reticular layer Sebaceous gland Dense Arrector pili muscle irregular Sweat gland duct Hair follicle Lamellated (pacinian) Hypodermis corpuscle Nerve fibers Sweat gland
Red and blue vessels = arterial Artery Cutaneous and venous blood; dead cells Vein plexus are farthest away from blood Fat Figure 5-1 The Components of the Integumentary System.
© 2015 Pearson Education, Inc. 4 What are the functions of the integumentary system?
Structure Function
Protection from environment Epidermis (chemicals, bacteria, etc.)
Sensory receptors Detect pressure, temperature, pain
(deliver nutrients, take away wastes); Blood vessels temperature regulation
Hair Insulation, skull protection
Sweat: cooling; sebaceous: keep Exocrine glands moisture in, anti-bacterial, protect hair
Nails Support/protect tips of digits 5 Layers of the Epidermis (Figure 5-3)
Stratum corneum = dead keratinocytes (produced by keratinization, a.k.a. cornification)
In between: 2-3 other layers
--Stratum basale = melanocytes, basal cells (epithelial stem cells) 6 Figure 5-4b Melanocytes (and keratinocytes)
Melanocytes Melanosome make melanin, transfer it to Keratinocyte keratinocytes via melanosomes Melanin (like vesicles) pigment Melanocyte
Basement membrane
Dermis
© 2015 Pearson Education, Inc. 7 Figure 5-6 Sources of Vitamin D3 Sunlight Food
Steroid compound Epidermis Vitamin D3 = Cholecalciferol Dietary cholecalciferol Digestive tract
Intermediary Liver product
Stimulation of calcium and phosphate ion absorption Calcitriol
Kidney © 2015 Pearson Education, Inc. (Ca and P mostly go to bone) 8 The epidermal response to UV light Melanin absorbs potentially harmful UV radiation Melanocytes are in the deepest layer of the epidermis (stratum basale), while most UV light hits the more superficial layers.
How do they sense and respond to UV light?
9 The epidermal response to UV light
Changes in gene expression => melanin production and export to the keratinocytes that need it most
Note: this is negative feedback!
Figure: Melanoma — Epidemiology, Genetics and Risk Factors by J.A. Orazio et al. (2013) 10 Keratin & Melanin [students sing underlined words] Keratin and melanin protect my skin. (Say it again!) Keratin and melanin protect my skin. (Say it again!)
Doo-doo-doo-duh-doo. Doo-doo-doo-duh-doo. Doo-doo-doo-duh-doo, doo-doo-doo-duh-doo. Doo-doo-doo-duh-doo-doo.
Keratin: Keeping water inside; making skin so strong; Melanin: Absorbing UV light when I’m in the sun too long. (a pigment, Keratin and melanin protect my skin. (Say it again!) not a Keratin and melanin protect my skin. (Say it again!) protein) Doo-doo-doo-duh-doo. Doo-doo-doo-duh-doo. Doo-doo-doo-duh-doo, doo-doo-doo-duh-doo. Doo-doo-doo-duh-doo-doo. 11 Melody playback: http://www.noteflight.com/scores/view/52e7c2a454794e24d250330c2913f2b59a62d85e
12 Melody playback: http://www.noteflight.com/scores/view/52e7c2a454794e24d250330c2913f2b59a62d85e
13 Figure 5-12a Hair Follicles and Hairs. Hair
Hair follicle develops from epithelial tissue (note keratinocytes Sebaceous forming the hair!) gland Arrector pili muscle Sebaceous glands often secrete oil into these ducts.
Hair is made out of Connective keratin (like skin). tissue sheath Root hair plexus
a Hair follicles, showing the associated accessory structures. © 2015 Pearson Education, Inc. 14 Sebaceous and Sweat Glands (These are exocrine glands, which make things other than hormones)
SWEAT GLAND SEBACEOUS GLAND Cooling (evaporation of H2O) oil: coats hair (protects), anti-bacterial, keeps moisture in
15 In-class worksheet, part 1
EASIEST to do without? Hair! (just wear a hat!) Erector pili!
HARDEST to do without? Epidermis = infections, not durable, water loss… Sweat glands (still have blood flow as another cooling system) Blood – some is definitely needed to keep cells alive! (Tactile receptors?)
16 Figure 5-16 Repair of Injury to the Integument (Part 1 of 4).
1 Inflammatory Phase
Epidermis
Dermis
What happened here? Knife wound, maybe… Anyway, there’s bleeding, and then the mast cells (pictured) release histamine and other chemicals to trigger inflammation. (As discussed previously: increased blood flow, swelling, heat, redness, etc.)
© 2015 Pearson Education, Inc. 17 Figure 5-16 Repair of Injury to the Integument (Part 2 of 4).
2 Migratory Phase
After a few hours: wound is filled in! A scab made of fibrin (protein from clotting blood). What else? What is migrating in the migratory phase? • Epithelial cells migrate down to new border. • Macrophages remove debris. • Fibroblasts come in as well. (What are they going to do?)
© 2015 Pearson Education, Inc. 18 Figure 5-16 Repair of Injury to the Integument (Part 3 of 4).
3 Proliferation Phase
Proliferation phase: what has proliferated? Fibroblasts, mostly – creating new collagen to replace fibrin.
© 2015 Pearson Education, Inc. 19 Figure 5-16 Repair of Injury to the Integument (Part 4 of 4).
4 Scarring Phase
4
Basically done. Is this the same as before? No – glands, muscle cells, nerves have been replaced. (A few blood vessels will be there.)
© 2015 Pearson Education, Inc. 20 Clinical applications: liposuction
• Where is the fat removed from?
Hypodermis.
• What are the possible complications?
• Bleeding – note all the blood vessels in the hypodermis • Sensory loss (note nerves in there) • Infection (penetrating epidermis) • Fluid loss (loss of epidermis reduces water conservation)
21 Clinical applications: burns (similar to liposuction risks) Risk? Treatment? Fluid loss Replace fluids (drinking, IV)
Heat loss Keep warm, but also give extra nutrients to maintain metabolic heat production (and promote healing) Infection Clean burns, antibiotics
22 Clinical applications: heat stroke
“About one of every 1,000 residents of the two cities was hospitalized for or died of heat-related illness.... Heatstroke rates were ten to 12 times higher for persons aged 65 years or older than for those younger than 65 years.” --T.S. Jones et al., “Morbidity and Mortality Associated With the July 1980 Heat Wave in St Louis and Kansas City, MO,” JAMA 1982
Elderly are more vulnerable to heat? Why might this be? Sweat less? Reduced blood flow to skin? Yes – both!
© 2015 Pearson Education, Inc. 23 In-class worksheet, part 2 21. Epidermis is water-resistant, so water does not pass through easily.
24. C (keratin) … but keratohyalin is also an excellent choice!
27. A (ability to thermoregulate) relates to both blood vessels AND sweat glands
29. Sunlight promotes production of vitamin D3 (cholecalciferol), which later becomes calcitriol in kidney (affects Ca and P retention). Be careful if child lives in cloudy place or doesn’t go outside much! Supplement diet with vitamin D, if needed.
30. Sweating increases conductance. 24