1. Skin and the Integumentary System
Chapter 6

2. Introduction
An organ is two or more tissues grouped together and performing specialized functions
The cutaneous membrane (skin) together with certain accessory organs make up the integumentary system

3. Integumentary system

4. Types of Membranes
Serous membranes – line body cavities that lack openings to the outside
Form inner linings of thorax and abdomen (visceral and parietal)
Cover the organs within these cavities
Secretes watery serous fluid, which lubricates membrane surfaces

5. Serous membranes

6. Mucous membranes – line cavities and tubes that open to the outside of the body
Include oral, nasal, and tubes of the digestive, respiratory, urinary, and reproductive systems
Secrete mucous from goblet cells

7. Synovial membranes – form the inner linings of the joint cavities between the ends of bones at freely movable joints (synovial joints)
Secrete a synovial fluid which lubricates the ends of bones within the joint

8. Cutaneous membrane - skin

10. Skin and its tissues What it does: Maintains homeostasis
Protective covering
Regulates body temp
Prevents water loss from deeper tissues
Houses sensory receptors
Creates biochemicals
Excretes small quantities of wastes

11. Has two distinct tissue layers: Epidermis – outer layers
Made of stratified squamous epithelium
Dermis – inner layer
Thicker than the epidermis and contains all other types of tissue
Beneath that is the subcutaneous layer which contains loose connective tissue and adipose tissue that connects it to organs

12. http://www. wildmedcenter. com/uploads/5/9/8/2/5982510/7422370_orig

13. Epidermis
Made of stratified squamous epithelium and lacks blood vessels
As the cells of the lower layer (stratum basale) divide they get pushed upward towards the surface and divide
These cells harden by the protein keratin filling into the cell membrane – Keratinization
This forms the outermost layer (stratum corneum)

15. The loss of skin cells is equal to the death in healthy skin
Rate of cell division increases in skin that is rubbed or pressed a lot (causes calluses or corns-keratinized masses on toes)
Functions: shields excessive water loss, mechanical injury and harmful chemicals, also keeps out disease-causing organisms when not cut

16. http://t0. gstatic. com/images

17. Skin color
Melanocytes are specialized cells in the epidermis which produce melanin, a dark pigment that provides skin color
They also absorb UV radiation in sunlight which prevents mutations and damaging effects
Located in deepest layer of epidermis

19. All people have the same # of melanocytes but the amount of melanin that they produce varies
Mostly genetically determined…more melanin produced, darker the skin
Sun causes additional pigment to be produced

20. sciencedaily.com

21. Dermis (fun fact)
The dermal papillae is uneven which causes fingerprints
This is due to genes and when the fetus presses against the uterine wall
skincarebylouisa.com

22. Dermis Binds the epidermis to underlying tissues
Made of dense connective tissue with collagenous and elastic fibers which gives skin toughness and elasticity
Filled with blood vessels which supply nutrients and also regulate body temperature

23. Also has nerve cells throughout which send impulses to sensory receptors (like touch)
It also contains hair follicles, sebaceous glands (oil producing), and sweat glands

24. http://www. wildmedcenter. com/uploads/5/9/8/2/5982510/7422370_orig

25. Subcutaneous layer
Beneath dermis and consists of loose connective and adipose tissue
No sharp boundary separates these two layers
Adipose helps insulate the body
This layer also contains the major blood vessels that supply the skin and underlying adipose tissue

26. health.rush.edu

27. Accessory organs of the skin: Hair Follicles
Hair is present except on the palms, soles, lips, nipples, and parts of reproductive organs
Hair follicle – tubelike depression in the skin in which hair develops
Hair is composed of dead epithelial cells that develop in the dermis and get pushed toward surface and keratinized

28. http://www. wildmedcenter. com/uploads/5/9/8/2/5982510/7422370_orig

29. A bundle of smooth muscle cells (arrector pili muscle) attaches to each hair follicle and contracts which makes hair stand up (goose bumps)

30. Sebaceous gland
Contain groups of specialized epithelial cells that secrete an oily mixture through ducts in hair follicle
Sebum is the mixture and it helps keep the hair and skin soft, pliable, and waterproof

31. Nails
Protective coverings on the ends of the fingers and toes made of keratinized epithelial cells
Made of a nail plate and overlies a nail bed
The lunula makes up the base of the nail plate and that is where the nail grows

32. http://www. handresearch. com/finger-nails/Menu_bestanden/nail-unit

33. Sweat glands
Exocrine glands made of a tube that starts in the subcutaneous layer and is lines with sweat-secreting epithelial cells
Two types:
Eccrine glands-respond to body temp, common in areas of lots of sweat (forehead)
Carried by a duct out a pore in the skin
Apocrine glands-active when a person is emotionally upset, frightened, or in pain
(ear wax and mammary glands are modified sweat glands)

35. Regulation of body Temperature
If too hot:
hypothalamus has muscles in the blood vessels relax and dilate (vasodilatation) which causes heat to leave blood through skin
Eccrine glands release sweat (evaporation cools skin)
If too cold:
Muscles next to blood vessels contract which causes (vasoconstriction) and less heat loss
Sweat glands are inactive
If keeps getting worse, skeletal muscles are forced to contract which increases cellular respiration and produces heat (shivering)

37. Healing of Wounds
Inflammation – when a wound an the area surrounding it become red and painfully swollen in response to injury or stress
Inflamed skin may become reddened, warm, swollen, and painful
Blood vessels dilate which allows more blood to flow to that area with helpful nutrients and oxygen

39. If break in skin is shallow:
Epithelial cells are stimulated to divide and new cells fill the gap
If injury extends into the dermis or deeper:
1.Blood vessels break and blood clots (forms scab)
2.Fibroblasts come and form new collagenous fibers that bind wound together
3.Blood vessels come back and phagocytic cells remove dead cells and other debris
4.Scab falls off and if wound is bad it forms a scar

41. Integumentary system review Video