The Integumentary System Chapter 5 Integumentary System Structure
The Integumentary System Chapter 5 Integumentary System Structure Epidermis Dermis Functions of the skin The Birthday Suit Combination of 4 main tissues
Epithelial outer layer Connective underlies dermis Smooth Muscle goose bumps Nervous sensory receptors Structure allows it to carry out many functions Protection, hydration, sensation, hair to color Very durable
Functions of the Skin Protection Temperature regulation Sensations Storage of chemical compounds Excretion of wastes
Synthesis of compounds Determines characteristics Structure of the Skin 2 principal parts Epidermis Dermis Beneath the dermis Hypodermis H u
Epidermis Stratified squamous epithelium Avascular Approximately every month we shed entire skin surface Consists of keratinocytes H u
Layers of the Epidermis (bottom to top) Stratum germinativum (stratum basale) Stem cells Stratum spinosum Cells look spiny Stratum granulosum Cells die Stratum lucidum Found only in thick skin
Stratum corneum Multiple layers Variations in Skin Color Pigments Melanin Produced by melanocytes Protects skin from UV rays Carotene Lack of pigment Albino
Pallor Pale or ashen Reduced blood flow H u White Genetic lack of melanin Jaundice Yellow Liver and
bilirubin Hematoma Bruise Epidermis and Dermis Epidermis is avascular Dermis is highly vascular Epidermis receives nourishment from dermis Cells far away from nourishment die Dermis
Largest part of the skin Connective tissue Contains Blood vessels Nerves Accessory structures 2 layers Papillary layer Reticular layer H u
Papillary Layer Most superficial layer Loose connective tissue Surface area increased by papillae Form fingerprints Human Anatomy, 3rd edition Prentice Hall, 2001 Reticular Layer Deeper layer Dense, irregular
connective tissue Contains Blood vessels Glands Deep pressure receptors Human Anatomy, 3rd edition Prentice Hall, 2001 Subcutaneous Layer Loose connective tissue Packed with
adipocytes Binds dermis to deeper tissue Stabilizes position of skin Adipose storage Aka hypodermis, superficial fascia Epidermal Derivatives Hair Glands Nails
Hair (Pili) Came with mammals Embryological development & distribution Life span of hair What does hair do for mammals? Functions of Hair
Protection Thermoregulation Sensory Minor role in humans Three Types of Hair Terminal Lanugo fine, downy, unpigmented hair of
fetus Vellus Course and pigmented Eyebrows, eyelashes and scalp After puberty Fine, unpigmented
2/3 hair of women 1/10 hair of men All of childrens except eyebrows, eyelashes and scalp 5-18 Axillary
Pubic Male facial hair Some hair of trunk and limbs Hair Structure Shaft Superficial Dead tissue Root Remainder of hair within follicle Dead tissue
H u Hair Structure Medulla Soft core Cortex Hard core Gives hair stiffness Cuticle
Outermost layer H u Hair Develops in Follicles Diagonal tube extending deep in dermis Two layers Epithelial root sheath Connective tissue root sheath Bulb contains matrix
Hair papilla Contains blood vessels and nerves Associated structures Hair receptors Arrector pili Arrector Pili
Smooth muscle attaches to follicle Raises hairs Emotional response, cold Function? Hair Growth and Loss (Scalp) Scalp 4 to 8 years Eyelashes 5 months Eyebrows 2 months 5-23
Sebaceous glands Glands Usually connected to hair follicles Secrete a waxy, oily substance (sebum) Develop in utero at about 5 months Secretion increases at puberty Glands
Sweat glands Eccrine glands Found just about everywhere (esp. palms & soles) Produce perspiration Water, salt, met. wastes Merocrine secretion http://www.pg.com/science/skincare/Skin_tws_35.h Glands Sweat glands (scent glands)
Specific type of sweat gland Found near hair follicles Axillary & genital regions Develop at puberty Called apocrine sweat glands Really merocrine secretion http://www.pg.com/science/skincare/Skin_tws_35.htm
The Skin with Sweat Glands Ceruminous Glands Found in auditory canal Cerumen Earwax Combination of sebum and dead epidermal cells Keeps eardrum pliable, waterproofs canal, kills bacteria, and coats guard hairs 5-28 Mammary Glands
Produce milk during lactation Not synonymous with breasts Small traces in both males and females Modified apocrine gland 5-29 Nails
Dorsal surfaces of ends of fingers & toes Primate feature Grasping Derivatives of stratum corneum Nail Structure Nail plate Free edge Nail body
Nail root Nail fold Nail groove Nail bed Hyponychium epidermis Nail matrix growth area Lunule Eponychium (cuticle) Skin Cancer Induced by UV rays (both natural and tanning
beds) Elderly and fair-skinned most common 3 types Basal cell carcinoma Squamous cell carcinoma Malignant melanoma 5-32 Basal Cell Carcinoma Most common Least dangerous: hardly metastasizes Arises in stratum
basale and invades dermis 5-33 Squamous Cell Carcinoma Arises from keratinocytes of stratum spinosum Can metastasize to lymph nodes Can be lethal 5-34
Malignant Melanoma Most deadly, but only 5% of cases Arises from melanocyte of existing mole Metastasizes quickly and often fatal if not treated quickly 5-35
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