1. Anatomy and Physiology
Marieb’s Human
Anatomy and Physiology
Marieb w Hoehn
Chapter 5
Integumentary System
Lecture 12
41 slides, 71 min

2. Suggested Study Method
1. Look at the items on your Study Guide that pertain to the topic for the upcoming lecture.
2.  Read the lecture material (see my suggestions below) BEFORE coming to class. TAKE NOTES from the material you are reading IN YOUR OWN WORDS.  While you’re reading, if you see something that was in the Study Guide, highlight it in your textbook.
3.  Take some notes in class during lecture if you need to, and then as soon as possible after class COMBINE your reading notes for that topic with your class notes - AND COMPLETE THE STUDY GUIDE FOR THAT SECTION.
   
4.   Once you’ve geared up to start studying for a test, try and CONDENSE your notes a little more without sacrificing.  REMEMBER, when studying for an exam, you are now using ONLY your notes, not your textbook (unless you need clarification about something).  Make sure you’ve gone over your notes and memorized them AT LEAST three times before the exam.
5.  Finally, get a BLANK Study Guide, put your notes aside then answer the questions on the study guide and compare your answers to your notes.  If you can’t answer the questions correctly or address the points on your Study Guide without looking at your notes, you’re not yet ready for the exam.  Review/re-memorize those things you are still not solid on. 
A suggested method for reading your text prior to coming to lecture is the following:
a.       Skim the chapter section HEADINGS first to get an overview of the chapter contents
b.       Look at all the figures in the text and read the legends for the figures/tables before you actually read.  Ask yourself what you know about the figures as you’re looking at them.
c.       Read over the Study Guide for the material (that I give you for each exam) before you read to focus your thoughts on the most important 20% of what  you will have to know.
d.       Read the Chapter summary (yes, BEFORE you read the Chapter) and while you’re reading through it keep asking yourself what you already know and what you don’t know, and focus on the things that are mentioned in your Study Guide.
e.       Read the chapter material and, using the Study Guide and the Expert Questions, make notes on what you’re reading.  Don’t COPY sentences in your textbook word-for-word, but put a summary sentence for each paragraph you read IN YOUR OWN WORDS.

3. Lecture Overview Functions of the Integumentary System
Overview of the skin
The epidermis
The dermis
The hypodermis (subcutaneous layer)
Accessory structures of the integumentary system
Injury and Repair
Aging and the integumentary system

4. Where are We in Our Organizational Scheme?

5. Some Questions…
Skin is composed of an epithelial layer and a connective tissue layer. Is skin a membrane?
Yes. The cutaneous membrane
What is a membrane?
Combination of ET and CT tissues combine to protect/cover other tissues
Is there a difference between the skin (integument) and the integumentary system?
Yes. Skin is the cutaneous membrane consisting of an epithelium (epidermis) and a dermis (CT). The integumentary system (IS) includes the skin, hair, nails, and glands (accessory structures).
How does the structure of the the integument, enable it to perform its functions of protection, temperature regulation, etc.?
That is the subject of this lecture…

6. Introduction to the Integumentary System
The integument constitutes 7% of our body weight and has a surface area of about 1.5 – 2.0 m2 (15 – 20 ft2)
Functions of the integument
Protection (from mechanical/chemical/bacterial damage, UV radiation)
Temperature regulation (extreme heat, extreme cold) and Fluid conservation
Excretion
Vitamin D production
Sensation (touch, pressure)

7. Overview of the Integument
SKIN
Accessory Structures
Epidermis = protection; Dermis = nourishment of epidermis; SubQ = insulation
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

8. Layers of the Epidermis - Overview

9. Cells of the Epidermis
Epidermis of the skin is classified as a keratinized stratified squamous epithelium
Cells of the epidermis include
Keratinocytes (90%)
Keratin – a tough, fibrous intracellular protein (protection)
Lamellar granules (waterproofing, extracellular)
Melanocytes (8%)
Produce melanin (protection from UV radiation)
Langerhans cells (1-2%)
Migrate to skin from bone marrow
Participate in skin’s immune response (dendritic cells)
Merkel cells (< 1%)
Least numerous; specialized epithelial cells
Function in sensation of touch

10. Thick and Thin Skin
Thin ( mm) (epidermal thickness)
Thick ( mm) (epidermal thickness)
Thick skin - palms of hands, soles of feet; five epidermal layers
Thin skin - everywhere else; four epidermal layers (no s. lucidum)
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

11. Layers of the Epidermis
basale
“Bare Skin Gets Lots of Cuts”
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

12. Layers of the Epidermis
Stratum basale (Bottom) (germinativum) - lowest layer
- single layer of dividing cells that continually replace more superficial epithelial cells - contains Merkel cells (touch) and melanocytes (pigment)
- attached by hemidesmosomes to underlying basal lamina
- epidermal ridges; contours of skin follow ridges = fingerprints
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

13. Layers of the Epidermis
Stratum spinosum (spiny)
layers of rounded cells with large nuclei
- held together by desmosomes
- cells continue to divide
- Langerhans (immune) cells found here *
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

14. Layers of the Epidermis
Stratum granulosum (granular)
- 3-5 layers of keratinocytes
- most no longer divide
- begin making lots of keratin and keratohyalin (KH) * cells flatten and harden * cell membranes thicken * KH promotes dehydration and cross-linking of keratin fibers * nuclei begin to disintegrate and cells die *
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

15. Layers of the Epidermis
Stratum lucidum (clear) - ONLY in THICK SKIN - flattened, densely packed, and filled with keratin (eleidin)
- separates the s. corneum from the s. granulosum
- Water resistant boundary layer of keratinized skin
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

16. Layers of the Epidermis
Stratum corneum (horny)
layers of dead keratinized cells (dander)
- exposed to outside
- tightly connected by desmosomes
- remain for about 2 weeks
- water-resistant * interstitial fluids slowly permeate and evaporate (insensible perspiration) * damage to epidermis greatly increases this water loss * fluid collection between cells creates blisters *
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

17. What’s hiding in your bed?
Mmmm…dander GOOOOD!
Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007
Dermatophagoides, The House Dust Mite

18. Skin Color Genetic Factors varying amounts and type of melanin
varying size/number of melanin granules
albinos lack melanin (but not melanocytes!)
Physiological Factors
dilation of dermal blood vessels (erythema)
constriction of dermal blood vessels (less pink, pale = pallor)
level of oxygenation of blood * normal = pink (fair-skinned) * low = bluish (cyanosis)
carotene -> Vit A (yellow)
jaundice (yellow)
Environmental Factors
sunlight
UV light from sunlamps
X rays

19. Skin Color From: phototune.com/images/SkinTune1.jpg

20. Skin Color and Melanin Melanocytes and melanin facts
Dark-skinned
Fair-skinned
Melanocytes and melanin facts
- tyrosine (aa)  melanin - UV radiation up-regulates production of melanin - Caucasian vs. dark-skinned * number vs. activity * layer of epidermis
Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004

21. Other Epidermal Facts Vitamin D3 (“sunshine vitamin”)
After UV irradiation epidermal cells in s. spinosum and s. basale convert a cholesterol-related steroid to Vit D3 (cholecalciferol)
Vit D3 –  absorption of calcium and phosphorus by small intestine
Epidermal Growth Factor (EGF)
Produced in salivary glands and duodenum
Widespread effects on epithelia
 cell division in s. basale and s. spinosum
 production of keratin
 epidermal development and repair
 synthetic activity and secretion by epithelial glands

22. Dermis
Papillary layer (contains papillae) - areolar connective tissue (CT) - capillaries and sensory neurons - dermal papillae - fingerprints (with epi. ridges)
Reticular layer (contains fibers) - dense, irregular CT - collagen fiber bundles extend upward and downward - also contains elastic fibers and cells of CT proper - accessory organs of integumentary system (from epi.) - cleavage or tension lines - flexure lines
Figure adapted from: Martini, Anatomy & Physiology, Prentice Hall, 2001

23. Dermis
Circulation - cutaneous plexus (CP) - branches of CP supply hair follicles, glands, other structures - form papillary plexus
Nerves - control blood flow - regulate gland secretion - monitor sensory reception - light touch (Meissner’s) - deep touch/pressure (Pacinian or lamellated corpuscles) - naked nerve endings to epithelium (pain, temperature)
Figure adapted from: Martini, Anatomy & Physiology, Prentice Hall, 2001

24. Subcutaneous Layer - Stabilization of dermis - INSULATION
Also called ‘hypodermis’. This is the superficial fascia.
- Areolar and adipose tissue
- Effect of hormones
- Reservoir of blood

25. Removal of Subcutaneous Fat - Liposuction
Figures from: and

26. Hair (pilo-) epidermal cells tube-like depression extends into dermis
Basal lamina
epidermal cells
tube-like depression
extends into dermis
hair root (in dermis)
hair shaft (outer 1/3)
hair papilla
dead epidermal cells
(from epidermis)
melanin
arrector pili muscle
Nerves in root hair plexus
Figure from: Hole’s Human A&P, 12th edition, 2010
A hair in the scalp grows for 2-5 years, about 0.33mm/day

27. Hair Follicles Types of hair:
Hair color
Types of hair:
1. Lanugo – long, blond, fine (fetal, anorexia nervosa)
2. Vellus – short, blond (children, adult females)
3. Terminal – coarse, pigmented (adults)
Some hair color
Figure adapted from: Martini, Anatomy & Physiology, Prentice Hall, 2001

28. Lanugo (Anorexic) Hypertrichosis Lanuginosa Acquisita (Malignant Down)
All Figures from Google (Images): Search “Lanugo”

29. Hairs Emerging from Follicles
Photo from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

30. Hair Color and Texture
Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

31. Sebaceous (Oil) Glands
Figure from: Hole’s Human A&P, 12th edition, 2010
usually associated with hair follicles
holocrine glands
secrete sebum, a waxy, oily material
absent on palms and soles
Lanolin of skin creams is sheep sebum.
Sebaceous follicles – not associated with hair. Discharge directly on to skin. On face, back, chest, nipples and male sex organs.
inhibits growth of bacteria
lubricates and protects keratin of hair shaft, and conditions skin

32. Sweat Glands also called sudoriferous glands
Sweating (usu excessive) with visible wetness = diaphoresis
also called sudoriferous glands
apocrine (merocrine secr.) glands - associated with hair follicles - thick, odorous secretion
eccrine (merocrine secr.) glands - most numerous - palms, soles, forehead, neck, back - directly on to surface - watery secretion - for thermoregulation
Figure from: Hole’s Human A&P, 12th edition, 2010
ceruminous glands
Specialized (apocrine secretion)
mammary glands

33. Nails Know these terms – be able to label a diagram of the nail
(Perionychium)
Fingernails grow about 1 mm/wk, toenails somewhat slower.
Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007
Know these terms – be able to label a diagram of the nail
Hyponychium

34. Nails – Sagittal Section Through Finger
Fingernails grow about 1 mm/wk, toenails somewhat slower.
Figure from: Anatomy & Physiology Revealed, McGraw Hill, 2007

35. Regulation of Body Temperature
Hyperthermia – Abnormally high body temperature
May be caused by - environment (heat, humidity) - illness (fever [>=37.20C], pyrexia) - anesthesia (malignant h.)
Corrected by loss of heat by radiation, convection, conduction, evaporation
Heat exhaustion (prostration) - Fatigue - Dizziness - Headache - Muscle cramps - Nausea - May lead to heat stroke
Figure from: Hole’s Human A&P, 12th edition, 2010
Malignant hyperthermia (MH) is an inherited autosomal dominant myopathy characterized by a hypermetabolic state which is triggered when the patient is exposed to some anesthetic agents (succinylcholine, fluranes). Caused by a mutation in the ryanodine receptor in SR so that excess Ca is released and less Ca is taken back up by the SR. Classic MH most often manifests in the operating room, but it can also occur within the first few hours of recovery from anesthesia. Consequently, muscle contraction is sustained, resulting in signs of hypermetabolism, including acidosis, tachycardia, hypercapnia, glycolysis, hypoxemia, and heat production (hyperthermia).
Some susceptible patients may develop MH despite multiple prior uneventful exposures to triggering drugs. Some other drugs have been found safe in patients susceptible to MH.
When MH is diagnosed early and treated promptly, the mortality rate should be near zero. Whenever anesthesia is administrated, dantrolene should be readily available as well as a protocol for management of MH. Dantrolene is, at the moment, the only known drug that treats MH. It impairs calcium-dependent muscle contraction and controls hypermetabolism manifestations.

36. Regulation of Body Temperature
Hypothermia – Abnormally low body temperature (at least 20C below normal body temp)
May be caused by:
- exposure to cold (primary)
- illness (secondary)
- surgical induction (clinical)
Cardiac arrest is likely if temperature falls below 28oC (82oF)
Corrected by mechanisms to retain body heat (see left)
Hypothermia - A condition in which the internal temperature of the (human) body is at least 3.6°F (2.0°C) below an internal temperature of 98.6°F (37°C). Hypothermia represents a continuum of effects that vary with the severity of cold on physiological systems. The human body needs a specific internal temperature that is regulated on a minute-by-minute basis to maintain all normal body functions. The many physiological and behavioral processes involved in maintaining the internal temperature constant are called thermoregulation.
Various environmental situations predispose humans to hypothermia, which can occur even in the absence of cold. In fact, hypothermia is more common in temperate regions than in the colder climates. Because of the uniqueness of the situations in which hypothermia can occur, various kinds of hypothermia have been classified, all of which can prove fatal.
Primary hypothermia
Primary hypothermia is a decrease in internal temperature that is caused by environmental factors in which the body's physiological processes are normal but thermoregulation capability is overwhelmed by environmental stress.
Secondary hypothermia - A decrease in core temperature caused by an underlying pathology that prevents the body from generating enough core heat is referred to as secondary hypothermia.
Figure from: Hole’s Human A&P, 12th edition, 2010

37. Healing of Cuts
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson
3. Epidermal cell migration and collagen production
4. Shedding of scab; covering of wound with epithelium
1. Bleeding/clotting
2. Scab formation
Tissue repair can occur by either: 1) regeneration – healing with tissue that was originally present 2) fibrosis – healing with ‘scar’ tissue

38. Burns
First degree burn - superficial partial-thickness - sunburn, momentary contact with hot object - injures only the epidermis - healing is rapid (2-3 days), usually with no scarring
Second degree burn - deep partial-thickness - longer contact with hot objects, hot liquids, flames - injures epidermis and part of dermis - blisters may form as fluid accumulates - degree of healing is dependent upon survival of accessory structures, i.e., hair follicles, sweat glands, and sebaceous glands – source of epithelial cells - healing occurs in 3-4 weeks - usually no scarring unless infection present

39. Burns
Third degree burn - full-thickness - destroys epidermis, dermis, and accessory structures - immersion in hot liquids, prolonged exposure to hot objects, flames, corrosive chemicals - healing involves epithelial cells at margin of injury
- usually extensive scarring
- repair may involve
autograft
homograft
various skin substitutes

40. Types of Burns
Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

41. Rule of Nines
Figure from: Hole’s Human A&P, 12th edition, 2010

42. Life Span Changes Scaly skin as sebaceous glands secrete less oil
Age spots
Dermis becomes reduced
Loss of fat
Wrinkles
Sagging
Melanin production slows
Hair thins
Number of hair follicles decrease
Impaired nail growth
Sensory receptors decline
Inability to control body temperature
Less vitamin D production

43. Review
The Integumentary System has numerous functions that are related to its composition and structure
Protection
Temperature regulation (sweat, blood vessels)
Excretion
Vitamin D production
Sensation (touch, pressure)
The epidermis – the outer, protective layer
S. basale, s. spinosum, s. granulosum, s. lucidum (thick skin only), s. corneum

44. Review The dermis – the lower, nutritive layer
Papillary dermis
Reticular dermis
Dermis contains accessory organs of skin
The hypodermis (subcutaneous) – insulates
The superficial fascia
‘baby fat’
reservoir of blood
NOT part of the skin

45. Review Accessory structures of the integumentary system Hair
Nails (parts of nails)
Sweat glands
Apocrine (merocrine)
Eccrine (merocrine)
Modified (mammary, ceruminous)
Sebaceous glands and sebaceous follicles
These structures are vital for skin repair since they act as a source of epithelial cells

46. Review Skin color is due to many factors Genetic (melanin)
Environmental (UV irradiation)
Physiologic
Dilation of dermal blood vessels – erythema
Poor oxygenation of blood – cyanosis
Constriction of dermal blood vessels – pale skin
Carotene, jaundice (yellow skin)

47. Review
Temperature regulation is an important function of the integumentary system
Body can lose heat by
Radiation
Evaporation
Convection
Conduction
Hyperthermia (ABOVE normal core temperature)
Dilation of dermal blood vessels
Increased sweat gland secretion
Hypothermia (BELOW normal core temperature)
Constriction of dermal blood vessels
Decrease in sweat gland secretion

48. Review
Stem cells in the epithelium and dermis are crucial to repair after injury
Wound healing and regeneration
Burns
Numerous changes occur in the integumentary system with age (Ugh!)