Ch. 4 Skin And Body Membranes


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Ch. 4 Skin And Body Membranes

  1. 1. Skin and Body Membranes Human Anatomy and Physiology Mr. McCammon
  2. 2. I. Classification of Body Membranes  Epithelial Membranes include the cutaneous membrane (skin) and the mucus membranes, and the serous membranes.  Always combined with an underlying layer of connective tissue.  That’s why it is considered an organ.
  3. 3. I. Classification of Body Membranes  Cutaneous Membrane – This is your skin. – Composed of keratinizing stratified squamous epithelium. – Underlying dermis is dense (fibrous) connective tissue. – Exposed to air and is dry.
  4. 4. I. Classification of Body Membranes  Mucous membranes (or mucosa) – composed of epithelium (the type varies from site to site) resting on a loose connective tusse membrane called a lamina propria. – Lines all the cavities that open to the exterior such as respiratory, digestive, urinary, and reproductive tracts. – Always moist because they are continually bathed in secretions.
  5. 5. I. Classification of Body Membranes  Serous Membranes (serosa) – Layer of simple squamous epithelium resting on a thin layer of areolar connective tissue. – Line the body cavities that are closed to the exterior (except for the dorsal body cavities and joint cavities) – Occur in pairs – parietal layer lines a specific portion of the wall of the ventral body cavity and folds in on itself to form the viseral layer with covers the outside of the organs in that cavity.
  6. 6. I. Classification of Body Membranes  The serous layers are separated by a clear fluid called serous fluid.  Important to decrease friction by moving organs (heart, stomach)  Some serous membranes – Peritoneum – abdominal cavity – Pleura – around the lungs – Pericardium – around the heart
  7. 7. I. Classification of Body Membranes  Synovial membranes are composed of connective tissue and contain no epithelial cells at all.  Line the fibrous capsules surrounding joints where they provide a smooth surface and secrete a lubricating fluid.  Contain small sacs of connective tissue called bursae and tubelike tendon sheaths – both cushion organs moving against each other during muscle activity.
  8. 8. II. The Integumentary System  The Skin – Includes cutaneous membrane, sweat and oil glands, hairs, and nails – External body covering – Keeps water and other molecules in the body. – Keeps and other things out – Pliable yet tough
  9. 9. II. The Integumentary System  Study chart on page 95.  The structure of the skin. – Epidermis  Stratified epithelium – becomes keratinizing (hard and tough) – Dermis  Dense connective tissue  Both connected tightly until a burn or friction causes a blister.
  10. 10. II. The Integumentary System  Deep down in the skin is the subcutaneous tissue or hypodermis – Basically adipose tissue – Not considered part of this skin, but does anchor the skin to the underlying organs. – Shock absorber and protected from temperature changes. – Makes you ‘curvy’
  11. 11. II. The Integumentary System  KNOW THE DIAGRAM ON PAGE 96.  The Epidermis in Detail – 5 zones (layers) called strata  In order, basale, spinosum, granulosum, lucidum, corneum.  They are avascular  Most cells are keratinocytes (produce fibrous protein that makes the epidermis tough.  Deepest layer is stratum basale lies closes to the dermis and contains the only cells that receive adequate nourishment via diffusion from the dermis.
  12. 12. II. The Integumentary System  Cells from the stratum basale are constantly dividing and pushed up to become part of the epidermis.  Stratum lucidum only occurs where the skin is hairless and extra thick (palms, feet)  Stratum corneum makes up ¾ of our body.  Constant replaced – New epidermis every 25-45 days.
  13. 13. II. The Integumentary System  Melanin – yellow to brown pigment is produced by cells called melanocytes found in the stratum basale.  Sunlight stimulates melanin production causes tanning.  Melanin forms a protective shield from sunlight so it doesn’t affect genetic material.  Freckles and moles are where melanin is concentrated in one spot.
  14. 14. II. Integumentary System  Excessive exposure can lead to skin cancer.  It can cause the elastic fibers to clump and lead to leathery skin.  Black people seldom have skin cancer because melanin is an effective shield against it.
  15. 15. II. The Integumentary System  The Dermis – Your ‘hide’ – strong, stretchy envelope that helps to hold the body together. Leather goods are just treated dermis of animals. – Two regions  Papillary layer  reticular layer
  16. 16. II. The Integumentary System  The Papillary Layer is the upper dermal region – Uneven with finger like projections called dermal papillae – Contain capillary loops which nourish the epidermis – Pain receptors touch Meissner’s corpuscles. – On hands and feet papillae are arranged in patterns to enhance gripping ability.
  17. 17. II. The Integumentary System  Reticular layer – Deepest layer – Contains seat, blood vessels, sweat and oil glands, deep pressure sensors called Pacinian corpuscles – Collagen and elastic fibers make it tough – Restrictions of blood in the dermis results in cell death and causes Decubitus ulcers (bedsores)
  18. 18. II. The Integumentary System  Skin Color – The amount and kind of melanin in the dermis – The amount of carotene deposited in the stratum corneum (carotene is an orange yellow pigment – The amount of oxygen bound to hemoglobin (pigment in red blood cells)
  19. 19. II. The Integumentary System  People with lots of melanin have brown- toned skin.  Light skinned people (caucasian) people have less melanin and have a crimson color due to oxygen-rich blood.  Then hemoglobin is poorly oxygenated the skin can become blue (cyanosis) – common during heart failure and breathing disorders
  20. 20. II. The Integumentary System  Skin color – Redness or erythema – may indicate embarrassment (blushing), fever, hypertension, inflammation, or allergy. – Pallor or blanching – becoming pale – fear, anger, stress, anemia, low blood pressure, impaired blood flow – Jaundice or yellow cast – liver problems – Bruises or black-and-blue marks – sites where blood has escaped from circulation and has clotted in the tissue spaces – called hematomas
  21. 21. III. The Appendages of the Skin  Cutaneous glands – all exocrine glands that release their secretions to the skin surface via ducts.  Two groups – Sebaceous glands – Sweat glands  Form in Stratum basale but push lower into the dermis
  22. 22. III. Appendages of the Skin  Sebaceous (oil) glands – found all over the body except palms of hands and feet.  Most open onto a hair follicle, but some open directly onto the skin.  Sebum is the name of the oil – mixture of oil and fragmented cells that keep the hair and skin moist. Kills bacteria  Increase in male hormones increase sebum during adolescence.
  23. 23. III. Appendages of the Skin  If a sebaceous gland’s duct becomes blocked by sebum a whitehead forms. If the whitehead dries it becomes a blackhead.  Acne is an active infection of the sebaceous glands  Severe acne results in scarring of the skin.
  24. 24. III. Appendages of the Skin  Sweat Glands – Sudoriferous glands  Can be as many as 2.5 million per person  Two types – Eccrine – Apocrine
  25. 25. III. Appendages of the Skin  Eccrine glands – More numerous – Produce seat  Water, salt, vitamin C, ammonia, urea, uric acid, and lactic acid (which attracts mosquitoes)  Sweat is acidic (ph 4-6) which kills bacteria  Reaches the skin by a funnel-shaped pore.  They secrete sweat when the external or body temperature is high.
  26. 26. III. Appendages of the Skin  When the sweat evaporates, it carries heat with it, cooling the body.  On a hot day the body can lose 7 liters of water per day.  A few degrees change in body temperature can radically alter body chemistry. Maintaining body temp. is very important to homeostasis.
  27. 27. III. Appendages of the Skin  Apocrine sweat glands are confined to the axillary and genital areas  Larger than eccrine glands  Ducts empty into hair follicles  Secretions contain fatty acids, proteins, as well as all the other stuff secreted by the eccrine glands.
  28. 28. III. Appendages of the Skin  The secretions can have a milky or yellowish color.  Odorless until bacterial that live on the skin use the proteins and fats as nutrients. Then it produces a musky unpleasant odor.  Begin to function during puberty.  A lot is unknown about these. They have almost no thermoregulatory function.  Become more active during stress or sexual foreplay.
  29. 29. III. Appendages of the Skin  There are millions of hairs scatterd all over the body.  Only a few serve an important function  Hair on head to protect brain from bumps.  Eyelashes shielding the eyes  Nose hairs keep particles from the respiratory tract.
  30. 30. III. Appendages of the Skin  Hairs original purpose was to keep the body warm.  Hair is produced by a hair follicle  Root hair is enclosed in the follicle.  The hair shaft extends out of the follicle.  Hair is formed by a division of the stratum basale called hair bulb matrix.
  31. 31. III. Appendages of the Skin  KNOW THE DIAGRAM OF A HAIR ON PAGE 100  Arrector pili muscles are part of the hair follicle that make the hair stand up and makes “goose bumps”
  32. 32. III. Appendages of the Skin  Nails are scalelike modifications of the epidermis that corresponds to the hoof or claw of other animals.  Each nail has a free edge, a body (visible portion), and a root (embedded in the skin)  Each nail has overlapping edges called nail folds.  Proximal nail fold is called the cuticle.
  33. 33. III. Appendages of the Skin  Stratum basale of the epidermis extends beneath the nail as the nail bed.  Nail matrix is responsible for nail growth.  The white cresent is called the lunula.  Nail is normally clear. Pink color is due to blood supply to the stratum basale.  When blood supply is low, nail becomes cyanotic.  KNOW THE DIAGRAM ON PAGE 102.
  34. 34. IV. Homeostasis  The skin has more than 1000 different ailments.  Athlete’s foot – itchy, red, peeling condition of the skin between the toes resulting from a fungal infection; tinea pedis  Boils and carbuncles – inflamation of the hair follicles and sebaceous glands, common on the dorsal neck. Carbuncles are caused by bacterial infection (usually Staphlococcus aureus)
  35. 35. IV. Homeostatis  Cold Sores – fever blisters – small fluid-filled blisters that itch and sting, caused by a herpes simplex infection. Localized in a cutaneous nerve, where it remains inactive until emotional upset – usually around the lips and oral mucosa  Contact dermatitis – itching, redness, and swelling of the skin, progressing to blistering. Exposure of the skin to chemicals the provokes an allergic response.
  36. 36. IV. Homeostatis  Impetigo – pink, water-filled, raised lesions of the mouth and nose that develops a yellow crust and eventually rupture. Very contagious – common in elementary school children.  Psoriasis – chronic condition, characterized by reddened epidermal lesions, covered with dry, silvery scales. Can be disfiguring. Cause is unknown .