CHAPTER 5 Flashcards
Functions of Skin
A. protection B. Homeostasis of Body Temps C. Cutaneous Sensation D Metabolic Functions E. Blood Reservoir F. Excretion
Protection
- Physical/mechanical: water resistant
- Chemical barriers; low ph secretions, sweat, sebum, antibiotics, melanin
- Biological; dendrite cellls, macrophages, DNA
Homeostasis
Vasodilation, vasoconstriction, sweat gland secretions
Vasodilation
dilation of blood cells. when its hot, blood is brouth closer to the external environment and heat is transfered to the water molecules of sweat
Vasoconstriction
narrowing of dermal blood vessels; external temp drops
Cutaneous Sensation
pacinian corpuscles meissners corpuscles markel cells hair follicle receptors free nerve endings
Pacinian copuscles
detect deep pressure
meissner’s corpuscles
detect touch
merkel cells
detect caresses
hairl follicle receptors
detect movement of hair
Free nerve endings
detect pain
Skin Structure
^ Epidermis: avascular
> Dermis: vascularized
v Hypodermis: vascular
Epidermal Layers
Stratum Corneum stratum Lucidum stratum granulosum stratum spinosum stratum basal
Stratum corneum
outer layer of single-like keratinized cells w/thick membranes, about 75% of epidermal thickness, waterproofing and protection from penetration/abrasion
Stratum Lucidum
Thin and transrosw of clear flat dead keratinocytes, visible only in thick skin
stratum granulosum
thin layer, keratinization begins- cells fill with keratin, cells flatten, nuclei and organelles start disintegrating, plasma membrane thickens, keratohyaline fill cytoplasm
Stratum Spinosum
several layers of keratinocytes held together by desmosomes, contain weblike system of intermediate filaments, resist tension, abundant melanin granules and langerhans cells
Stratum Basale
deepest layer, single row of youngest keratinocytes and melanocytes, keratinocytes undergo rapid division
Dermal layers
papillary and reticular
Papillary layer
areolar CT; collagen and ellastic fibers
Dermal papillae- papillary loops, free nerve endings, meisseners corpuscle
Epidermal Ridges- finger prints
Reticular Layer
80% of dermis
dense fibrous connective tissue, contains glands nerves, hair follicle etc.
Hypodermis
Subcutaneous layer
- adipose
- store fat
- anchors skin to underlying structures
Skin Color
Melanin: yellow to tan or reddish brown to black
Carotene: orange
Hemoglobin: pinkish
Sebaceous Gland
secrete sebum, can kill bacteria, base of hair follicle
Eccrine/merocrine sweat glands
palms, pads, heads
Apocrine sweat glands
axillary and anogenital regions (armpits, pubic region), secrete proteins and lipids
Ceruminous glands
ear cannals- ear wax (cerumen)
Types of skin cancer
Basal cell Carcinoma
squamous cell carcinoma
malignant melanoma
Basal Cell Carcinoma
almost never metastasize beyond original tumor site
Squamous cell carcinoma
epidermis, caused by UV
Malignant Melanoma
cancer in melanocytes; can beginn wherever there is pigment. life threatening
