BIO 110 1. © 2011 Pearson Education, Inc. 1) Thermoregulation – controlling body temperature 2)...

BIO 110

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© 2011 Pearson Education, Inc.

1) Thermoregulation – controlling body temperature2) Blood reservoir – carries 8 – 10% of the blood when at

rest in an adult3) Protection – a barrier to microorganisms, chemicals etc.4) Sensation - sensory receptors provide us tactile

sensation, thermal sensation and pain5) Excretion (sweating) and absorption (e.g., fat soluble

vitamins A,D,E & K, some drugs etc.)6) Synthesis of Vitamin D

Copyright 2010, John Wiley & Sons, Inc.


Cutaneous membrane layers1. Epidermis (epi, above)2. Dermis

Hypodermis (subcutaneous layer)

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Accessory structures◦ Hair ◦ Nails◦ Sweat gland◦ Sebaceous gland◦ Arrector pili muscle◦ Nerve fibers and sensory receptors◦ Cutaneous plexus (network of blood vessels)

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© 2011 Pearson Education, Inc. 5

The structure of the skin, or integument, which consists of the cutaneous membrane and accessory structures

Cutaneous Membrane

The epidermis (epi, above)consists of a stratifiedsquamous epithelium.

Dermis

Papillary layer

Reticular layer

The dermis consists of apapillary layer of areolartissue and a reticular layer ofdense irregular connectivetissue.

The hypodermis(subcutaneous layer orsuperficial fascia) separatesthe integument from thefascia around deeper organs.Note that this tissue is notpart of the integument.

Hair shaft

Pore of sweatgland duct

Tactile corpuscle

Sebaceous gland

Arrector pili muscle

Sweat gland duct

Hair follicle

Lamellated corpuscle

Nerve fibers

Sweat gland

Artery

VeinFat

The network ofarteries and veinsconnected to smallervessels servicing thetissues of the integu-mentary system is thecutaneous plexus.

Accessory Structures

© 2011 Pearson Education, Inc.Copyright 2010, John Wiley &

Sons, Inc.


Epithelial cells that secrete a substance. 3 kinds of exocrine glands in the skin:

1) Sebaceous (oil) glands- sebum2) Sudoriferous (sweat) glands- aprocrine and eccrine 3) Ceruminous glands- ear wax


© 2011 Pearson Education, Inc.Copyright 2010, John Wiley &

Sons, Inc.


1) Melanocytes◦Manufacture melanin◦ Differences in skin pigmentation is not number of melanocytes

but varying cell synthetic activities◦ Albinism (albin- = white) is the inherited inability of an

individual to produce melanin

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2) Hemoglobin, the oxygen-carrying pigment in red blood cells

Responsible for the blush (erythema) of the skin when we are embarrassed

Or the hyperemia when we apply heat Pallor results when the circulation is compromised e.g.,

shock, anemia3) Carotene a yellow-orange pigment Precursor to Carotene is Vitamin A



The steps in the regeneration of the skin after injury

Initial Injury After Several Hours

Immediately after theinjury, mast cells inthe region trigger aninflammatoryresponse.

Bleedingoccurs at thesite of injury.

Epidermis

Dermis

The blood clot, or scab, that forms at the surfacetemporarily restores the integrity of the epidermis andrestricts the entry of additional microorganisms into thearea. The scab is red due to the presence of trapped redblood cells.

Macrophages patrol thedamaged area of thedermis, phagocytizingdebris and pathogens.

If the wound occupies an extensive area or involves a regioncovered by thin skin, dermal repairs must be under way beforeepithelial cells can cover the surface. Divisions by fibroblasts andmesenchymal cells produce mobile cells that invade the deeperareas of injury. Endothelial cells of damaged blood vessels alsobegin to divide, and new capillaries grow in behind thefibroblasts, enhancing circulation. The combination of blood clot,fibroblasts, and an extensive capillary network is calledgranulation tissue.

Cells of the stratumbasale undergo rapiddivisions and begin tomigrate along the edgesof the wound in anattempt to replace themissing epidermal cells.


Over time, deeper portions of the clot dissolve, andthe number of capillaries declines. Fibroblastactivity leads to the appearance of collagen fibersand typical ground substance. The repairs do notrestore the integument to its original condition,however, because the dermis will contain anabnormally large number of collagen fibers andrelatively few blood vessels.

After One Week After Several Weeks

Severely damaged hair follicles, sebaceousor sweat glands, muscle cells, and nervesare seldom repaired, and they too arereplaced by fibrous tissue. The formation ofthis rather inflexible, fibrous, noncellularscar tissue completes the repair processbut fails to restore the tissue to its originalcondition.

FibroblastsScartissue

The steps in the regeneration of the skin after injury


Cicatrix◦ Growth of fibrotic tissue after damage, Scar

Keloid◦ Raised thickened mass of scar tissue◦ Grows into surrounding dermis◦Most often in dark-skinned adults

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◦ Fewer melanocytes◦ Thinning, drier epidermis◦ Diminished immune response◦ Thinning dermis◦ Decreased perspiration◦ Reduced blood supply◦ Slower skin repair◦ Fewer active follicles◦ Altered hair and fat distribution


• Boil (or furuncle) is a skin disease caused by the infection of hair follicles, resulting in the localized accumulation of pus and dead tissue. Individual boils can cluster together and form an interconnected network of boils called carbuncles.


• A cyst is a closed sac having a distinct membrane and division on the nearby tissue. It may contain air, fluids, or semi-solid material. A collection of pus is called an abscess, not a cyst. Once formed, the cyst could go away by itself or may have to be removed using surgery.


• Tinea infections are caused by fungi. • Athlete's foot (tinea pedis)• Tinea cruis- Jock itch• Tinea corpus- ringworm• Tiniea capitus- ringworm of the scalp

Tinea


Impetigo (sometimes impetaigo) is a superficial bacterial skin infection most common among children 2 to 6 years old. It begins as a itchy red rash that develops into pustules the form a yellow crust.


A wart (also known as verruca) is generally a small, rough tumor that can resemble a cauliflower or a solid blister. Warts are common, and are caused by a viral infection, specifically by the human papillomavirus (HPV) and are contagious when in contact with the skin of an infected person.


An ulcer is a discontinuity of the skin exhibiting complete loss of the epidermis and often portions of the dermis and even subcutaneous fat.

Decubitus ulcers (Bedsores) occur when there is consistent pressure against the skin. Very common in bedridden patients.


Infection with the herpes simplex virus (HSV) is categorized into one of several distinct disorders based on the site of infection. Oral herpes (HSV I), vesicles (blisters) form on the face and mouth and are called cold sores. Oral herpes is the most common form of infection. Infection of the genitals (HSV II), commonly known as herpes, is the second most common form of herpes. Vesicles can appear on the genitials.

HSV


Chicken Pox Shingles

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• Psoriasis is a chronic, autoimmune disease which affects the skin and joints. It commonly causes red scaly patches on the skin. Skin rapidly grows at these sites and takes on a silvery-white appearance.


Dermatitis is a blanket term meaning any "inflammation of the skin" (e.g. rashes, etc.). There are several different types of dermatitis. The different kinds usually have in common an allergic reaction to specific allergens. The term may be used to refer to eczema, which is also known as dermatitis eczema or eczematous dermatitis.


The term eczema is broadly applied to a range of persistent skin conditions.

The following can be characteristics of eczema: redness, skin edema (swelling), itching and dryness, crusting, flaking, blistering, cracking, oozing, or bleeding


Hair follicles blocked by excess sebum and broken down keratin cells from the base of the hair follicle.

Blackheads and whiteheads (comedones) can change into pustules.

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Alopecia- Loss of hair, baldness

Hirsutism- excessive Hairiness

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Albinism-a defect of melanin production that results in little or pigment in the skin, hair, and eyes.

a defect of melanin production that results in little or no color (pigment) in the skin, hair, and eyes.

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Skin cancers (most common types of cancer)◦ Types

Basal cell carcinoma Most common skin cancer Originates in stratum basale in response to UV radiation Virtually no metastasis and most people survive

Malignant melanoma Cancerous melanocytes Commonly metastasize through lymphatic system Detected early, 5-year survival is 99% Not detected until metastasis, 5-year survival is 14%


Methicillin-resistant Staphylococcus Aureus (MRSA) is a type of staph bacteria that is resistant to certain antibiotics. This condition very difficult to treat.

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◦ Condition resulting in poorly mineralized bones

◦ In children, develops from not enough sunlight or not enough dietary cholecalciferol (Vitamin D) Uncommon in United States

◦ In elderly, skin production of cholecalciferol decreases by 75%

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Pediculosis- Lice Scabies- Itch Mite


Rosacea is a chronic skin condition characterized by redness, swelling and skin sores that look like acne.

Sometimes called “adult acne”

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A wheal is small, itchy swelling of the skin.Can relate to an insect bite or hives

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A contusion (bruise) is a type of hematoma of tissue[in which the blood vessels are damaged by trauma, allowing blood to leak into the surrounding interstitial tissues.

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BIO 110 1. © 2011 Pearson Education, Inc. 1) Thermoregulation – controlling body temperature 2)...

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