Integumentary System

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Integumentary System

• Nestor T. Hilvano, M.D., M.P.H

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Learning Objectives

• You should be able to
• Describe the histological structures of the
  integument including the layers of the epidermis
  and dermis.
• Discuss the functions of the skin and
  subcutaneous tissue.
• Discuss the skins color and pigmentation.
• Describe the histology of hair and hair follicle.
• Explain how a hair grow and distinguish the types
  of hair.
• Describe the anatomical structure of nails and
  how they are formed.
• Describe the structure and function of glands in
  the skin.
• Explain how the skin responds to injury and
  aging.

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Skin

• Largest organ (15 of body weight)
• 2 main layers
• a) ______________
• b) ______________
• Rest on stroma (supporting tissue)
• called ___________.
• Functions
• Protection or defense
• Excretion of materials by glands
• Synthesis of Vitamin D3 (cholecalciferol)
  synthesis
• Sensory receptors pain, temperature, touch,
  pressure and vibration
• Thermoregulation
• Storage of lipids

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Layers of the Epidermis

• Thick skin- located on palms and soles 5 layers
  
• Stratum germinativum
• Stratum spinosum
• Stratum granulosum
• Stratum lucidum
• Stratum corneum
• Thin skin- located on general region of the body
  3 layers
• Stratum germinativum
• Stratum spinosum
• Stratum corneum
• general region of the body
• palm and soles

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Epidermis of Thick Skin Layers

• Stratum germinativum (basale)- deepest layer
  basal cells, melanocytes, and merkel cells
  epidermal ridges (fingerprints)
• Stratum spinosum- spiny layer due to shrinkage
  dendritic (Langerhans) cells
• Stratum granulosum - grainy layer, 3 to 5
  layers flat keratinocytes contain keratohyaline
  granules
• Stratum lucidum - clear (prickle cell) layer
  keratinocytes with eleidin, a precursor to
  keratin
• Stratum corneum- superficial layer dead, scaly,
  keratinized cells barrier water resistant shed
  every 2-4 weeks
• Psoriasis results from increase in the mitotic
  rate of the germinativum causing epidermal layer
  replaced within a wk.
• ___ What cells are capable of initiating an
  immune response?
• ___ What layer of epidermis contain
  non-nucleated, squamous
• cells?
• ___ What pigment cells are found at stratum
  basale?

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Skin Colors

• Melanin brown, yellow- brown, or black pigment.
  
• ___ flat pigmented spots.
• ___ clusters of pigmented cells, raised or
  flat.
• ___ most serious type of skin cancer.
• ___ homozygous recessive trait disorder caused
  by the absence of the pigment melanin (in skin,
  hair, or eyes).
• ___ pigment loss due to antibodies attacking
  melanocytes.
• a. albinism b. freckles c. vitiligo
• d. malignant melanoma e. moles (nevi)

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Skin Colors

• ___ blueness from deficiency of oxygen in the
  circulating blood (cold weather)
• ___ redness due to dilated cutaneous vessels
  (anger, sunburn, embarrassment)
• ___ yellowing of skin and sclera due to excess
  of bilirubin in blood
• a. erythema b. jaundice c. palor d. cyanosis

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Dermis

• Connective tissue layer
• papillary layer or dermal papillae
• - areola (LCT) tissue
• - meissners corpuscle
• - dermatitis
• b) reticular layer
• - Dense Irregular CT
• - accessory organs
• Why does inflammation of the skin is painful?

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Hypodermis

• Also called subcutaneous tissue or superficial
  fascia
• Functions
• energy reservoir
• thermal insulation
• What types of tissues is hypodermis composed of?
  _______.
• What is liposuction? ____.
• Why does subcutaneous injections of drugs has
  faster rate of absorption? ____.

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Hair and Hair Follicle

• Hair is a keratinous strand produced by
  epithelial cells of hair follicle
• Hair bulb is where hair originates
• Hair papilla provides nutrients
• Epithelial root sheath extension of epidermis
• Connective tissue root sheath derived from the
  dermis
• Arrector pili muscle contraction causes goose
  flesh
• Hair matrix is important for growth
• Human hair can support 3 kg. (6.6 lb)

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Sweat Glands

• ____ glands is simple tubular gland
• help cool the body
• ____ glands produce sweat containing fatty acids
• found only near hair follicles
• bromhidrosis is body odor produced by bacterial
  action on fatty acids

a. apocrine sweat glands b. eccrine (merocrine)
sweat glands
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Sebaceous Glands

• Oily secretion called sebum
• Flask-shaped gland with duct that opens into hair
  follicle
• ___ What type of gland is sebaceous gland as to
  manner of secretion?

a. merocrine (eccrine) b. apocrine c. holocrine
d. endocrine
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Homework (Self-Review)

1. Define the following melanocytes, jaundice,
   cyanosis, arrector pili muscle, merocrine sweat
   gland, apocrine sweat gland, sebaceous gland,
   hair matrix, langerhans cell, dermis,
   subcutaneous tissue, dermatitis, albinism,
   vitiligo, freckles, moles, keratinocytes, merkel
   cells, and erythema.
2. Describe briefly the 5 layers of epidermis in
   thick skin.
3. Discuss why hypodermic injection has faster rate
   of drug absorption?
4. Classify type of skin in a) palms, b) chest, c)
   face, d) trunk, e) buttocks, f) soles