The%20Integumentary%20System

1
The Integumentary System

• Human Anatomy Physiology I

2
Introduction

• Integumentary (inte whole gument body
  covering)
• Helps protect the body, helps maintain a constant
  body temperature, and provides sensory
  information about the environment.
• Of all the bodys organs, none is more easily
  inspected or more exposed to infection, disease,
  and injury than the skin.

3
Introduction
4
Introduction
5
Functions of the skin

• Helps regulate body temperature
• Serves as water repellent
• Protective barrier between the external
  environment and internal tissues

6
Functions of the skin

• Excretes a small amount of salts and several
  organic compounds
• Some capacity to absorb substances
• Helps synthesize the active form of vitamin D

7
Thermoregulation

• Two (2) ways
• By liberating sweat
• By adjusting the flow of in the dermis

8
Protection

• Bacterial infection
• Mechanical injury
• Chemical injury
• Dehydration
• UV radiation

9
Cutaneous Sensations

• Tactile sensations
• Tactile touch
• Pressure
• Vibration
• Tickling
• Thermal sensations
• Pain

10
Excretion

• Elimination of substances from the body
• Water evaporation (about 400 mL/daily)
• Sedentary person loses and additional 200 mL per
  day as sweat
• Sweat (vehicle for excretion of salts, CO2,
  ammonia urea)

11
Absorption

• Certain lipid-soluble materials
• Fat soluble vitamins
• Certain drugs
• Gases (O2 CO2)
• Toxic materials (mercury)
• Toxins (poison ivy)

12
Synthesis of vitamin D

• Requires activation of a precursor molecule in
  the skin (UV rays)
• Enzymes in liver kidney modify the activated
  molecule finally producing calcitriol (most
  active form of vitamin D)
• Calcitriol is a hormone that aids in the
  absorption of calcium in the GI tract

13
Structures of the skin

• Epidermis (epi above)
• Dermis
• Hypodermis (hypo below)

14
Epidermis

• The epidermis is keratinized stratified squamous
  epithelium.
• 4 types of cells
• 4 to 5 strata or layers (depending on the
  location)

15
Types of cells

• Keratinocytes most of the skin cells
• Tactile (Merkel) cells receptor/sensation
• Melanocytes production of the pigment melanin
• Langerhans immune response

16
Layers of the epidermis

• Stratum basale
• Stratum spinosum
• Stratum granulosum
• Stratum lucidum
• Stratum corneum

17
Stratum Germinativum (Basale)

• Deepest layer (closest to dermis)
• Single row of cuboidal or columnar keratinocytes
• Some cells in the layer are stem cells (undergo
  cell division to continually produce new
  keratinocytes)

18
Stratum spinosum

• Superficial to stratum basale
• 8 to 10 layers of keratinocytes
• Projections of both Langerhans and melanocytes
  also appear in this stratum

19
Stratum granulosum

• 3 to 5 layers of flat keratinocytes
• Marks the transition between the deeper,
  metabolically active strata and the dead cells of
  the more superficial strata.

20
Stratum lucidum

• Present only in the thick skin of the fingertips,
  palms, and soles
• 3 to 5 layers of flattened clear, dead
  keratinocytes
• Large amount of keratin

21
Stratum corneum

• 25 to 30 layers of flattened dead keratinocytes.
• Cells are continuously shed and replaced by cells
  from the deepest strata.
• Constant exposure of skin to friction stimulates
  the formation of a callus (abnormal thickening of
  the stratum corneum).

22
Dermis

• Composed mainly of connective tissue containing
  and elastic collagen fibers.
• Blood vessels, nerves, glands, and hair follicle
  are embedded in the in dermal tissue.

23
Dermis

• Two layers
• Papillary layer
• Reticular layer
• Dermal papillae extensions of the dermis into
  the epidermis
• forming the ridges of the fingerprints

24
Hypodermis

• Deep to the dermis, but not part of the skin!
• Mostly adipose tissue
• Serves as a storage depot for fat and contains
  large blood vessels that supply the skin.

25
Hair

• Hair on the head guards the scalp from injury and
  the suns rays.
• Decreases heat loss from the scalp.
• Eyelashes and eyebrows protect the eyes from
  foreign particles.
• Sensory (touch receptors)

26
Nails

• Nails are plates of tightly packed, hard,
  keratinized epidermal cells.
• Nail body visible part
• Free edge extend past the distal end of the
  digit
• Nail root portion that is buried in a fold of
  skin
• Lunula whitish, crescent-shaped

27
Sweat (sudoriferous) gland

• There are two main types eccrine and apocrine
  sweat glands.
• The cells of sweat glands release their
  secretions by exocitosis and empty them into hair
  follicles of onto the skin surface through pores.

28
Eccrine sweat glands

• Distribution Throughout the skin
• Location of secretory portion mostly deep in
  dermis
• Termination of excretory duct surface of
  epidermis
• Secretion less viscous consist of water, ions,
  urea, uric acid, ammonia, glucose, and lactic
  acid
• Functions thermoregulation, and waste removal
• Onset of function soon after birth

29
Apocrine sweat glands

• Distribution skin of axilla, groin, areola, and
  bearded regions of face
• Location of secretory portion mostly in
  subcutaneous layer
• Termination of excretory duct hair, follicle
• Secretion more viscous consist of same
  components as eccrine sweat glands plus lipids
  and proteins
• Functions stimulated during emotional stress and
  sexual excitement
• Onset of function puberty

30
Sebaceous (oil) glands

• Usually connected to hair follicles.
• They are absent in the palms and soles.
• Sebaceous glands produce sebum, which moistens
  hairs and waterproofs the skin.
• Clogged sebaceous glands may produce acne.

31
Hyperthermia

• Increased blood and internal temperature.
• Increased temperature is sensed by the
  hypothalamus.
• Vasodilation occurs in skin blood vessels so more
  heat is lost from the skin.
• Sweat glands become active, increasing
  evaporative heat loss.
• Body temperature decreases!

32
Hypothermia

1. Decreased blood and/or skin temperature.
2. Decreased temperature is sensed by the
   hypothalamus.
3. Vasoconstriction occurs in skin blood vessels so
   less heat is loss to the environment.
4. Skeletal muscles are activated, causing
   shivering, which increases metabolism and
   generates heat.
5. Body temperature increases.