Integumentary System

1
Integumentary System

• Chapter 5

2
The SkinOverview of Functions

• Largest organ
• 7,600 cm2
• Resistance to trauma and infection
• Water retention
• Vitamin D synthesis
• Thermoregulation
• Sensory reception
• Nonverbal communication

3
The Skin--Structure

• Epidermis
• Stratified squamous epithelium
• Dermis
• Dense irregular and elastic connective tissue
• Blood capillaries and nerves, receptors, etc.
• Hypodermis
• Subcutaneous layer
• Adipose and loose connective tissue
• Blood vessels and nerves
• Not actually a part of the skin.

4
Epidermis

• Layers (lower and upper)
• Stratum basale
• Single layer of cells
• Mitotically active
• Includes melanocytes (produce the pigment
  melanin) and keratinocytes (produce the protein
  keratin)
• Stratum corneum
• Keratinization causes cells to flatten and form a
  resistant outer layer
• Lack nuclei
• Death of cells results because of distance from
  blood supply in the dermis
• Cells are continuously shed and replaced from
  below

5
Dermis

• Innervation, blood supply, strength
• Papillary layer
• Contact with epidermis
• Papillae form base for friction ridges
• Reticular layer
• Strong and resilient
• Dense irregular connective tissue
• leather

6
Hypodermis (Subcutaneous Layer)

• Not part of skin
• Binds skin to underlying muscle
• Components
• Loose connective tissue
• Adipose tissue
• Blood vessels and nerves

7
Skin Color

• Melanin
• Eumelaninbrown-black
• Pheomelaninred-yellow

8
Epidermal Variations

• Thin Skin
• Basale, granulosum, corneum
• Eyelid and tympanic membrane (eardrum)
• Thick Skin
• All layers
• Lucidum (lips, soles, palms only)
• Surface Patterns
• Fingerprints (elastic fibers within dermis pull
  on epidermis)
• Flexion lines or creases (acquired from repeated
  contractions of muscles below)

9
Epidermal Derivatives--Hair

• Hair Structure
• Follicleepidermal (stratum basale) invagination
  into dermis.
• Dermal papilla supplies blood for nutrition of
  cells growing in bulb region. Cell death and
  keratinization occurs as cell are pushed away
  from dermal papilla.
• Shaft, root, bulb

10
Epidermal Derivatives--Nails

• From stratum corneum of epidermis
• Heavily keratinized
• Growth occurs as superficial cells of nail matrix
  are transformed into nail cells, which are pushed
  forward during growth.

11
Epidermal Derivatives--Glands

• Originate epidermally, located dermally
• Types
• Sebaceous (oil) glands
• Sudoriferous (sweat) glands
• Ceruminous (wax) glands

12
Epidermal DerivativesSebaceous Glands
Sebaceous gland

• Associated with hair follicle
• Secrete sebum
• Lubricates and waterproofs the stratum corneum

13
Epidermal DerivativesSudoriferous Glands

• Evaporative cooling through perspiration
• Two types
• Merocrine
• Widely distributed over body
• Cooling
• Apocrine
• Larger, open via hair follicle
• Axillary and pubic regions
• Odoriferous (sexual attractant)
• Mammary glands
• Specialized apocrine glands

14
Epidermal DerivativesCeruminous Glands

• External auditory canal
• Secrete cerumen (earwax)
• Water and bacteria repellent, keeps tympanic
  membrane pliable

15
Skin--Laboratory Observations

• Skin
• Epidermis
• Stratum basale
• Stratum corneum
• Dermis
• Papillary layer
• Reticular layer
• Hypodermis

• Scalp
• Same as Skin
• Hair
• Shaft
• Root
• Bulb
• Hair follicle
• Dermal papilla
• Sebaceous glands
• Sudoriferous glands
• Piloerector muscle

16
Integumentary System Review

• Name three functions of the skin that do not
  begin with the words Protection from
• The majority of epidermal cells are called
  __________.
• Cells of the __________ layer of the epidermis
  are mitotically active.
• Blood supply for the epidermis is found in the
  __________ layer of the dermis.
• The _____________ is not really a layer of the
  skin. It contains lots of adipose tissue.
• In response to cold, fear, or other stimuli this
  muscle contracts to make hair stand on end and
  causes goose bumps.
• Identify the structures in the following slides.

17
Skin Histology
a. (The layer)
c.
b. (The layer)
http//www.usuhs.mil/pat/surg_path/nlhist/pictures
/nl0026a.gif
d.
http//www.histol.chuvashia.com/atlas-en/skin-en.h
tm
18
Answers

• Vitamin D synthesis, sensation, temperature
  regulation, nonverbal communication.
• Keratinocytes
• Stratum basale
• Papillary layer
• Hypodermis
• Piloerector muscle

• Slides
• Stratum corneum
• Stratum basale
• Sebaceous gland
• Hair bulb