A&P I Integumentary notes
A&P I Integumentary notes BIOL 2500 - 018
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This 5 page Class Notes was uploaded by Margaret Notetaker on Wednesday September 16, 2015. The Class Notes belongs to BIOL 2500 - 018 at Auburn University taught by Shobnom Ferdous in Fall 2015. Since its upload, it has received 61 views. For similar materials see Human Anatomy and Physiology I in Biology at Auburn University.
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Date Created: 09/16/15
CHAPTER 5 THE INTEGUMENTARY SYSTEM Largest organ on body covers 2 square meters Composes 16 of your body weight Deeper layers are very vascular 2 major regions epidermis amp dermis Epidermis Avascular outermost layer Keratinized strati ed squamous epithelium Thickest layers on palms of hands amp soles of feet Cells are called keratinocytes except for stratum basale New cell production happens by mitosis 0 Older cells are pushed up by the production of new cells 0 New skin every 2545 days 4 Types Keratinocyte o Produces keratin o Keratin is an intracellular brous protein for water proo ng o Produced at the basal layer and pushed upwards o Tightly connected by desmosomes Melanocyte o Synthesizes melanin 0 Found in the deepest layer 0 Made in melanosomes I Synthesized in intercellular vesicles that carry melanocytes to keratinocytes o Protects us from harmful UV rays Merkel Cells 0 Found in the epidermal dermal junction 0 Associated with nerve endings o Merkel cell nerve touch receptor Langerhans Cells 0 Synthesize in bone marrow and migrate to epidermis o Macrophages that activate the immune system 0 The 2nd line of defense Layers Stratum Comeum o Super cial layer exposed to the outside 0 2030 layers of keratinized cells with thickened plasma membranes 0 Prevents dehydration of lower layers 0 Full of glycolipids that act as waterproof layers 0 Entire layer replaced during a 4 week period Stratum Lucidium o Appear clear under a microscope o Densely packed with eleiden CHAPTER 5 THE INTEGUMENTARY SYSTEM I Eleiden is a clear protein that is waterproof I Derived from keratohyalin 0 Only found in areas with the thickest skin palms ngertips soles of feet Stratum Granulosum 0 Layer is alive but beginning to die 0 Has keratohyaline granules which form keratin 0 Has lamellated granules which form waterproofing glycolipids Stratum Spinosum o Weblike system of intermediate prekeratin filaments 0 Attached to desmosomes to resist tension and pulling o Scattered among keratinocytes and dendritic cells 0 Has melanin granules amp Langerhans cells Stratum Basale Germinatium o Deepest layer 0 Connects the epidermis to the basal lamina 0 Single row of stem cells that actively mitosize I 1 daughter cell rises to top layer of epidermis I 1 daughter cell remains for more mitosis o Melanin that is produced is transported up to stratum spinosum 0 Has the smallest amount of merkel cells Dermis Core of the integumentary system innermost layer Dense irregular connective tissue Full of collagen bers amp elastin fibers 2 Layers Papillary Layer 0 Just below the stratum basale of the epidermis o Areolar connective tissue with collagen amp elastin 0 Has dermal papillae that extend into the epidermis I Combined with dermal ridges to form fingerprints I Has meissners corpuscles touch receptors Reticular Layer 0 Makes up 80 of the dermis o Dense irregular connective tissue with collagen amp elastin o Elasticity amp collagen lock in water hydration 0 Has exor lines I Holds near joints where skin cannot move Hypodermis Not true integument but important for the body Fat stores for insulation amp shock absorption Anchors skin to bone amp muscle Pathway for blood amp nerve vessels to reach the dermal layer CHAPTER 5 THE INTEGUMENTARY SYSTEM Pigmentation amp Skin Color 3 Main Pigments Melanin Carotene Hemoglobin Melanin 0 Made from Tyrosin amino acid 0 Color depends on enzyme in melanocyte tyrosinase I Cuts amino acid chain at different lengths I All depends on amount amp color of melanin o Freckles amp moles are accumulation of melanosomes 0 Light stimulates melanocytes to produce melanin Carotene o Accumulates in stratum comeum o Yelloworange color Accessory Structures Glands Sweat Sudoriferous o Eccrine merocrine I Hypotonic sweat via exocytosis I Deeply coiled in the dermis with the releasing duct in the epidermis I Secretes water salt vitamin C blood ltrate microbialcide dermicidin nitrogenous wastes I Found everywhere but nipples amp genetalia I Maintains homeostasis o Apocrine I Only found in armpit amp pubic region I Odorless when released but emits odor when bacteria breaks it down I Activates at puberty and secretes under nervous and hormonal control I Secretes viscous milkyyellow sweat with fatty substances amp proteins I Ceruminous glands ear wax Modi ed apocrine glands found in the lining of the ear Secrete a sticky bitter substance called cerumen Mammary Sebaceous oil 0 Everywhere but palms and soles of feet 0 Secretes sebum oily lipid and cell fragments o Softens amp lubricates hair and skin 0 Blackhead is oxidized amp dried excess sebum o Whitehead is an infected gland Hair Keratinous lamentous growing out of the epidermis dead cells Sense head hair guards against heat loss physical trauma light lters things Anagen growing phase 0 Active for about 610 years Catagen regressive phase 0 Cells that synthesize hair die CHAPTER 5 THE INTEGUMENTARY SYSTEM Telegen resting phase 0 Once this is over the cells create new hair again Follicle 0 Matrix is the actively dividing area of the bulb 0 Each has an arrector pili muscle smooth muscle 0 Contracts with cold amp fright o DHT controls the follicular growth cycle Nails Hard keratin layers on outside of epidermis Barriers Chemical 0 Acidity amp skin secretions kill bacteria 0 Protective peptides amp melanin block UV Rays Physical o Glycolipids for waterproo ng 0 Continuity of cells blocks germs 0 Hair insulates and protects from harmful particles Biological o Langerhan s cells activate the immune system 0 Macrophages absorb the harmful microorganisms Others 0 Body temperature maintains homeostasis o Sensory receptors in epidermis and dermis Skin Disorders Basal Cell Carcinoma Squamous Cell Carcinoma o Lesions form on head ears scalp lower lip amp hand 0 Second most common Melanoma 0 Cancer of the melanocytes 0 Highly metastatic amp resistant to chemotherapy Tissue damage from excessive heat or chemical exposure Loss of body uids renal failure amp circulatory shock 0 1st Degree 0 Most common 0 Average sunburn 211d Degree 0 Painful blisters form 0 All epidermis amp top of dermis is damaged 3rd Degree 0 Lost uids must be immediately replaced via an IV 0 Blackened greywhite or cherry red 0 Not painful because the nerves are destroyed 0 Usually skin grating is advised CHAPTER 5 THE INTEGUMENTARY SYSTEM Rule of 9s O 0000 O Divides the body into 11 important sections that account for 9 of the total body Head amp Neck 9 Upper limbs 18 Trunk 36 Perineum 1 Lower limbs 36 Developmental Infancy gt Adulthood O 0 Aging 0 0 Skin thickens amp gains more subcutaneous fat After 30 the skin starts to deteriorate Epidermal replacement slows down resulting in brittle skin Increased risk of cancer because there are less melanocytes
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