1. The Skin “The Players in the Layers”

2. Introduction
Structure
Epidermis
Dermis
Subcutaneous Layer – Fat Layer

3. Functions of the Skin Protection – barrier to disease
Temperature regulation
Sensations – touch
Excretion of wastes - water
Determines characteristics – skin colour, markings

4. The Skin FG04_02.JPG Title: Components of the Integumentary System
Notes: Relationships among the major components of the integumentary system (with the exception of nails, shown in Figure 4-15).
Keywords: integumentary system, cutaneous, epidermis, dermis, papillary layer, reticular layer, hair follicles, exocrine glands, nails

5. Epidermis Layers of flat squished cells – like the tiles on your roof
Over most of the body it’s thin – like a piece of paper
Approximately every month we shed entire skin surface (28 days)

6. Epidermis FG04_03.JPG Title: The Structure of the Epidermis
Notes: A light micrograph through a portion of the epidermis, shows the major stratified layers of epidermal cells.
Keywords: epidermis, structure, layers, stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum germinativum, dermis

7. Replacement of Epidermal Cells
Base of epidermis
New cells are pushed toward surface
New epidermal cells produce keratin
Cells are flattened as they are pushed upwards
Cells die
Outermost layer
Cells are dead, filled with keratin
Takes about two weeks for an epidermal cell to move from the bottom layer to the top

8. Pigments Humans have a pigment known as melanin in their skin.
Melanin is produced by cells called melanocytes.
Melanin is responsible for the color of our skin tone and can provide some UV rays protection .

9. Melanocytes and Melanin
FG04_06B.JPG
Title: Melanocytes
Notes: The micrograph and accompanying draiwing indicate the location and orientation of melanocytes in the stratum germinavatum.
Keywords: melanocytes, stratum germinavatum, melanin, basement membrane

10. Epidermis and Dermis Epidermis has low blood supply
Dermis has lots of blood
Epidermis receives nourishment from dermis
Cells far away from nourishment die

11. Dermis Largest part of the skin Connective tissue Contains
Blood vessels
Nerves
Glands
Hair follicles

12. Papillary Layer of the Dermis
Outermost layer of the skin
Surface area increased by papillae
Little Grooves
Form fingerprints
double row of papillae in finger pads produces the ridged fingerprints
Has lots of sensory receptors Papillary Layer

13. Deeper Layer of the Dermis
Dense connective tissue
Contains
Blood vessels
Glands
Deep pressure receptors
Attached to underlying organs by the subcutaneous layer

14. Subcutaneous Layer
Loose connective tissue which are packed with fat cells
Stabilizes position of skin

15. Epidermal Parts
Hair
Glands
Nails

16. Functions of Hair Protection Thermoregulation Sensory
Minor role in humans

17. Functions of Hair

18. Hair Structure Shaft Above the surface of the skin Root
Below the surface

19. Hair Structure FG04_10A.JPG Title: Hair Follicles
Notes: Hairs originate in complex organs termed follicles. (a) A longitudinal section and a cross section through a hair follicle. (b) and (c) A section along the longitudinal axis of a hair follicle.
Keywords: hair follicle, longitudinal section, cross section, sebaceous gland, arrectory pili muscle, cortex, cuticle, internal root sheath, connective tissue layer, glassy membrane, external root shaft 19

20. Hair Structure Medulla Soft core of hair Cortex
Hard core that gives hair its stiffness
Cuticle
Outermost layer of hair

21. Arrector Pili Smooth muscle attaches to follicle Raises hairs
Response to fright or cold
Function?
Generate heat

22. Glands Sebaceous glands Connected to hair follicles
Secrete a waxy, oily substance (sebum)
Secretion increases at puberty

23. Sebaceous Glands FG04_13A.JPG Title: Sebaceous Glands and Follicles
Notes: The structure of sebaceous glands and sebaceous follicles in the skin.
Keywords: sebaceous glands, sebaceous follicles, structure, sebum, germinative cells

24. Glands Sweat glands Found just about everywhere Produce “perspiration”
Water, salt, and metabolic wastes.
Function – cooling of the body

25. Glands Scent Glands Specific type of sweat gland
Found near hair follicles
Auxiliary & genital regions
Develop at puberty

26. Nails Dorsal surfaces of ends of fingers & toes Primate feature
Grasping

27. Nail Structure
Nail body
Free edge
Nail root
Matrix
Lunula (moon)

28. Nail Structure FG04_15.JPG Title: Structure of a Nail
Notes: These drawings illustrate the prominent features of a typical fingernail as view from the surface and in section.
Keywords: fingernail, hyponychium, nail bed, lateral nail groove, lunula, eponychium, phalanx, dermis, epidermis