University:
Texas A&M University
Course:
BIOL 319 | Integrated Human Anatomy and Physiology I
Academic year:

2024
Views:

209

Pages:

98
Author:

Tyshawn Shaffer

INTEGUMENT Objectives • Distinguish between the 5 layers of epidermal cells in thick skin and the differences in these found in thin skin. • Describe the organization of the two layers comprising the dermis. • Detail the structure of the sebaceous gland, eccrine sweat gland, and aprocrine sweat gland. • Recognize melanin and its functional significance. BINARY ORIGIN OF SKIN EPIDERMIS – ECTODERM 31 BINARY ORIGIN OF SKIN EPIDERMIS – ECTODERM DERMIS MESODERM 31 Functions of skin PROTECTS AGAINST INJURY AND DESICCATION MAINTENANCE OF WATER BALANCE Functions of skin PROTECTS AGAINST INJURY AND DESICCATION MAINTENANCE OF WATER BALANCE EXCRETES VARIOUS SUBSTANCES Functions of skin PROTECTS AGAINST INJURY AND DESICCATION MAINTENANCE OF WATER BALANCE EXCRETES VARIOUS SUBSTANCES THERMOREGULATION Functions of skin PROTECTS AGAINST INJURY AND DESICCATION MAINTENANCE OF WATER BALANCE EXCRETES VARIOUS SUBSTANCES THERMOREGULATION RECEIVES STIMULI • TEMPERATURE • PAIN • PRESSURE Functions of skin PROTECTS AGAINST INJURY AND DESICCATION MAINTENANCE OF WATER BALANCE EXCRETES VARIOUS SUBSTANCES THERMOREGULATION RECEIVES STIMULI • TEMPERATURE • PAIN • PRESSURE BASIS OF RECOGNITION AND YIELDS CLUES TO ONE’S WELL BEING Functions of skin PROTECTS AGAINST INJURY AND DESICCATION MAINTENANCE OF WATER BALANCE EXCRETES VARIOUS SUBSTANCES THERMOREGULATION RECEIVES STIMULI • TEMPERATURE • PAIN • PRESSURE BASIS OF RECOGNITION AND YIELDS CLUES TO ONE’S WELL BEING FAT METABOLISM IN THE SUBCUTANEOUS LAYER Integument CHARACTERISTIC THICK SKIN THIN SKIN Surface Texture Alternating ridges and grooves Smooth Epidermis/Dermis Interface Interdigitating ridges Less prominent ridges Epidermal Strata • • • • • • Same as thick skin, except: no S. Lucideum. • The corneum, granulosum, and spinosum layers are reduced in thickness. Hairs and Sebaceous Glands None Regionally variable Sweat Glands Abundant Moderate S. Basale S. Spinosum S. Granulosum S. Lucidum S. Corneum REGIONAL VARIATION OF THE EPIDERMIS THICK SKIN - SOLE OF FOOT (1.4 mm THICK) THIN SKIN - EYELID AND MOST OF BODY (0.07 TO 0.12 mm) CORNEA OF EYE - TRANSPARENT APPENDAGES - HAIR FOLLICLES NAILS GLANDS REGIONAL VARIATION OF THE EPIDERMIS Thick Skin (ventral surface of finger) Epidermis ) Adipocytes - Dermis Hypodermis Thick Skin (ventral surface of finger) Epidermis Copyright McGraw-Hill Companies Papillary layer Dermal papillae Epidermal peg Dermis Reticular layer Dermal side of the Epidermal – dermal interface Thick Skin (ventral surface of finger) Meissner’s corpuscles in dermal papillae Epidermis Epidermal peg Dermal papillae Dermis Meissner’s corpuscle is a mechanoreceptor Epidermis nerve ending for sensitivity to light touch; you would find more on your fingers because they are more sensitive to touch than your elbow. Skin hand monkey Hypodermis Papillary layer Dermal papillae Epidermal peg Skin hand monkey Eccrine sweat glands Adipocytes Hypodermis Pacinian corpuscles Papillary layer Dermal papillae Epidermal peg Obesity is characteristic of having a thickened subcutaneous layer LAYERS OF THE EPIDERMIS: PALMS AND SOLES OF FEET STRATUM CORNEUM • KERATINIZED FLATTENED, DENUCLEATED, DEAD CELLS LAYERS OF THE EPIDERMIS: PALMS AND SOLES OF FEET STRATUM CORNEUM • KERATINIZED FLATTENED, DENUCLEATED, DEAD CELLS STRATUM GRANULOSUM • KERATOHYALIN GRANULES LAYERS OF THE EPIDERMIS: PALMS AND SOLES OF FEET STRATUM CORNEUM • KERATINIZED FLATTENED, DENUCLEATED, DEAD CELLS STRATUM GRANULOSUM • KERATOHYALIN GRANULES STRATUM SPINOSUM • TONOFIBRILS DESMOSOMES LAYERS OF THE EPIDERMIS: PALMS AND SOLES OF FEET STRATUM CORNEUM • KERATINIZED FLATTENED, DENUCLEATED, DEAD CELLS STRATUM GRANULOSUM • KERATOHYALIN GRANULES STRATUM SPINOSUM • TONOFIBRILS DESMOSOMES STRATUM BASALE • CONTINUAL RENEWAL OF EPIDERMIS Thick Skin (ventral surface of finger) cont. Keratohyalin granules Desmosomes Hemidesmosomes 1 2 3 2 3 4 5 4 1. Stratum corneum 2. Stratum lucidum 3. Stratum granulosum 4. Stratum spinosum 5. Stratum basale 5 Thick Skin on finger cont. Keratohyalin granules S. granulosum: flattened cells undergoing Stratum the terminal granulosum differentiation process of keratinization – . forming the skin’s barrier against water loss when sealed with contents of membrane coating granules. Desmosomes Hemidesmosomes Stratum lucidum 1 Stratum spinosum Stratum basale Thick Skin on finger cont. The epidermis of thick skin is subject to continuous friction and pressure so the abundant desmosomes (and tonofibrils) withstand this and hold the cell layers together. Keratohyalin granules Desmosomes Hemidesmosomes 1 Epidermis Stratum spinosum Dermis Stratum basale STRATUM CORNEUM STRATUM GRANULOSUM STRATUM SPINOSUM STRATUM BASALE STRATUM BASALE STRATUM SPINOSUM STRATUM SPINOSUM STRATUM SPINOSUM STRATUM SPINOSUM STRATUM SPINOSUM EM 8g of skin: Note the different layers and the cellular contents of each 1. Stratum corneum 2. Startum granulosum 3. Stratum spinosum STRATUM CORNEUM STRATUM GRANULOSUM STRATUM CORNEUM STRATUM CORNEUM Cells in EPIDERMIS STRATIFIED SQUAMOUS CELL TYPES INCLUDE: KERATINOCYTES - MAIN CELL TYPE – ECTODERM MELANOCYTES PIGMENTATION - NEURAL CREST LANGERHANS CELL IMMUNOLOGIC ROLE MERKEL CELLS ASSOCIATED WITH NERVE ENDINGS MELANOCYTE – PIGMENT SYNTHESIS The embryonic origin of melanocytes is the neural crest derivatives NEURAL CREST ORIGIN (EYE & CNS) that migrate into the embryonic epidermis’ stratum basale. 111 107 111 107 111 107 MELANOCYTE - PIGMENT SYNTHESIS MELANOGENESIS CYTOCRINE SECRETION - PASS MELANIN GRANULES TO KERATINOCYTES CYTOCRINE SECRETION - PASS MELANIN GRANULES FROM MELANOCYTES TO KERATINOCYTES MELANOCYTE - PIGMENT SYNTHESIS LOCATED IN THE STRATUM BASALE CLEAR CELL - NO DESMOSOMAL CONNECTION Thin Skin (scalp) Stratum corneum Stratum granulosum Stratum spinosum Stratum basale Thin Skin (scalp) Sun from NASA Stratum corneum Stratum granulosum Stratum spinosum Stratum basale Melanin capping of nuclei Thin Skin (scalp) Sun from NASA Stratum corneum Stratum granulosum Stratum spinosum 4 Stratum basale Melanin capping of nuclei Melanin granule accumulate over the nuclei of mitotic cells of the stratum basale to protect nuclear DNA from UV damage. Melanocytes respond to melanocyte stimulating hormone secreted by the pars intermedia. 107 MELANOCYTE - PIGMENT SYNTHESIS SUSCEPTIBLE TO HORMONES AND PHYSICAL FACTORS • SUN-TANNING • SEX DIFFERENCES • PREGNANCY MELANOCYTE DENSITY SIMILAR IN ALL HUMANS MELANOCYTE DENSITY - SIMILAR IN ALL HUMANS MELANOCYTE - PIGMENT SYNTHESIS FRECKLES - MELANIN DISTRIBUTED IN PATCHES MELANOCYTE – disease states ALBINISM - FAILURE TO PRODUCE MELANIN MALIGNANT MELANOMAS - CANCER ADDISON’S DISEASE - PIGMENT DEPOSITION IN SKIN DUE TO ADRENOCORTICAL INSUFFICIENCY LANGERHANS CELLS BONE MARROW ORIGIN LOCATED IN STRATUM SPINOSUM GOLD CHLORIDE STAIN CLEAR CELL - NO DESMOSOMES DENDRITIC CELL LANGERHANS CELLS DENDRITIC CELL ROD OR RACKET SHAPED GRANULES FUNCTION IMMUNOLOGIC ROLE AS AN ANTIGENPRESENTING CELL CONTACT ALLERGIC RESPONSES AND OTHER CELL MEDIATED REACTION OF THE SKIN Epidermal – dermal interface Epidermal – dermal interface MELANIN is produced by MELANOCYTES 107 MELANIN-producing enzymes in MELANOCYTES Space of removed dermis EPIDERMIS 107 Epidermal – dermal interface face trunk nipple finger Epidermal – dermal interface - finger pad Epidermal – dermal interface finger pad Skin, foot 408 Epidermal – dermal interface creates unique finger ridges Thick Skin (Pacinian corpuscle and melanin) Pacinian corpuscle Melanin pigment Melanin capping of nuclei Pacinian corpuscles are mechanoreceptors that detect vibration and pressure. 105monkey finger Pacinian corpuscles are mechanoreceptors that detect vibration and pressure. 105 monkey finger Pacinian corpuscles Skin, scalp Thin Skin (scalp) - Hair follicle location Arrector pili muscle Sebaceous glands Skin, scalp 209 Skin, scalp sebaceous glands Skin, scalp Mode of secretion of the sebaceous glands is holocrine where by the sebum is released when cells burst. sebaceous glands Skin, scalp Mode of secretion of the sebaceous glands is holocrine where by the sebum is released when cells burst. sebaceous glands Eccrine sweat glands Eccrine sweat glands 105 Recto -anal junction Sebaceous gland Hair follicle Eccrine sweat glands Stratified squamous epithelium of anal wall Simple columnar epithelium of rectum with goblet cells Recto-anal junction hair Sebaceous gland Apocrine sweat gland MECHANISM FOR RELEASE OF SECRETORY PRODUCTS MEROCRINE SECRETION – EXOCYTOSIS W/O LOSS OF SURFACE MEMBRANE MECHANISM FOR RELEASE OF SECRETORY PRODUCTS MEROCRINE SECRETION – EXOCYTOSIS W/O LOSS OF SURFACE MEMBRANE APOCRINE SECRETION – LOSS OF PART OF APICAL CYTOPLASM AND SOME PLASMA MEMBRANE MECHANISM FOR RELEASE OF SECRETORY PRODUCTS MEROCRINE SECRETION – EXOCYTOSIS W/O LOSS OF SURFACE MEMBRANE APOCRINE SECRETION – LOSS OF PART OF APICAL CYTOPLASM AND SOME PLASMA MEMBRANE HOLOCRINE SECRETION – RELEASE OF WHOLE cell OTHER GLANDS OF EPIDERMAL ORIGIN SWEAT GLANDS • ECCRINE - COMMON SWEAT GLAND LOCAL COOLING • APOCRINE AXILLARY REGION - FUNCTION IN ANIMALS SWEAT GLANDS secretions SWEAT GLANDS secretions Thick Skin (ventral surface of finger) Myoepithelial cells are eosinophilic because of the presence of muscle contractile proteins, which contract to expel sweat when needed. Ducts of eccrine sweat glands with stratified cuboidal epithelium Myoepithelial cells Eccrine sweat glands SWEAT GLANDS Functional diversity of skin PROTECTS AGAINST INJURY (e.g.,UV light or mechanical stresses) AND DESICCATION MAINTENANCE OF WATER BALANCE EXCRETES THERMOREGULATION RECEIVES STIMULI FAT METABOLISM THREE TYPES OF GRANULES IN KERATINOCYTES MELANIN • SKIN PIGMENT • PRODUCED BY MELANOCYTES AND PASSED BY CYTOCRINE SECRETION TO KERATINOCYTES MEMBRANE COATING GRANULES (LAMELLATED GRANULES) • WATER PROOFING FUNCTION • PRODUCED BY KERATINOCYTES KERATINOHYALIN GRANULES • PRODUCED BY KERATINOCYTES THREE TYPES OF GRANULES IN KERATINOCYTES MEMBRANE COATING GRANULES (LAMELLATED GRANULES) • Small, ovoid structures from the Golgi containing various lipids and they undergo exocytosis to produce a lipid-rich impermeable layer around the cells of the s. granulosum – water proofing. THREE TYPES OF GRANULES IN KERATINOCYTES KERATINOHYALIN GRANULES • CHEMICAL NATURE NOT CLEARLY ESTABLISHED • RICH IN HISTODINE FORMS • MATRIX OF CELLS IN STRATUM CORNEUM, STABILITY DUE TO DISULFIDE BONDS • ABSENT IN HAIR AND NAILS 111 Melanocytes in Skin Regeneration of epidermis Clinical Correlation Albinism can be caused by a hereditary defect in tyrosinase activity or the inability of cells to take up tyrosine. Patient with albinism would be more at risk for the development of basal and squamous cell carcinomas as albinism produces skin hypopigmentation so fewer melanin granules to protect nuclear DNA from the ionizing, mutagenic effects of UV radiation. Tyrosine amino acid figure Albino peacock -

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