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34 Cards in this Set

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In the most vague terms, what is skin and what are its functions/
Large organ with these functions: mechanical protection, moisture barrier, host defense, thermoregulation, excretion of salt, synthesis of vit D and reg of calcium absorbption, sensory organ.
Describe 3 skin appearance concerns in clinical exams.
Jaundice- yellow, Cyanosis- gray, Pale- anemia
What are the 3 main layers of skin?
Epidermis, dermis, hypodermis.
What is another name for hypodermis?
Superficial fascia
What is the epidermis made of?
Kertanizing (cornified) stratified squamous epithelials of 4 types: keratinocytes, merkel cells, melanocytes, langerhans cells.
What are kartinocytes?
The major cell type of epithelial layer, provides barrier function, produces vit D precursor. Forms strat squamous barrier.
What are merkel cells?
Special cells derived from neural crest (ectodermal derivative), harder to see, sensory receptor.
What are melanocytes?
Make pigment, derived from neural crest.
What are langerhans cells?
Come from bone marrow, potent antigen presenting cells for T-lymphocytes.
Describe the stratification of teh keratinocytes during differentiation.
Starts at basal layer at tips of dermal papillae, next- spinosome (spiny) held together by desmosomes which when processed look spiny, next- granulosa layer with packets of material and finally corneum layer.
Which layer is mitotically active?
Basal layer
Describe the basal layer.
Also called stratum germinativum, single layer of cells all attached to basement layer by hemidesmosomes, mitotically active of keratinocytes, 15-30 day renewal
What is the role of desmosomes and hemidesmosomes in the basal layer?
Desmosomes connect cell to cell, hemidesmosomes attached cell to basement membrane.
What are lamellar bodies (Odland bodies)?
The outer layer of cells in the spinosum layer has these bodies containing glycolipid.
What are special features of spinosum layer?
Many desmosomes, abundant keratin fibers, some mitosis.
What are features of Stratum Granulosum?
The lamellar bodies extrude glycolipid to create intercellular glue
What are features of stratum lucidum?
Waxy cell envelope containing keratin, doesn't stain well, found primarily in thick skin.
What are features of stratum corneum?
Waxy cell envelope containing keratin. Non nucleated, dead cells.
What are features of merkel cells?
migratory cells located in stratum basale, mechanoreceptor cells, joined to adjacent keratinocytes by desmosomes. Cyto has small dense granules.
How do Merkel cells do their job?
They are in contact with afferent myelinated nerve fiber coming in from dermis. Nerve fiber loses myelin sheath as it penetrates basement membrane. Forms a terminal disk at pt of contact with Merkel cell membrane.
Describe features of melanocytes.
Neural crest derivatives, reside in or below basal layer. No junctions with keratinocytes, they extend cellular processes b/w keratinocytes in basal and spiny layer. Make melanin.
What is melanin?
Pigment derived from tyrosine, produced by melanocytes, stored in melanosomes. Released into extracellular space. Protects from UV rays by locating in keratinocytes in a peri-nuclear location.
What are langerhans cells?
Migratory cells derived from bone marrow. No junctions with other cells in epidermis. Found in outer s. spinosum. Come and go b/w dermis and epidermis, presenting antigens to immune system, carry antigens to lymph nodes via afferent lymph. Hard to see.
What is the 2 types dermis?
Papillary dermis- loose CT, Reticular dermis- dense irregular CT
What are the eccrine sweat glands?
Responsible for thermoregulation and mineral excretion. Simple coiled gland. Derived from ectoderm.
Describe features of eccrine gland as an excretory duct.
stratified cuboidal epithelium, responsive to aldosterone, water and salt resorption.
Describe features of eccrine gland as a secretory duct.
Secrete water and electrolytes. Total mass of eccrine sweat glands is equiv to kidney.
What causes salty kisses?
Mutation in a Cl- ion transporter CFTR- cystic fibrosis. High salt content in sweat is diagnotic for cystic fibrosis.
What are apocrine sweat glands?
Incorrectly named,should be merocrine secretion. Coiled tubular gland with lumen larger than eccrine. Ducts empty into canal of hair follicle. Located in axillary and genital areas. Function unknown, bacteria action on secretion = smelly.
What are sebaceous glands?
Associated with hair shaft, secretes sebum by holocrine secretion.
What is sebum?
Secretion of sebaceous gland made of waxes, cholesterol, triglycerides. May serve as substrate for bacteria and cause acne.
What are arrector pili muscle?
Small muscles attached to hair follicle. When contracted, makes hair stand up (like in cat or when you are cold). Causes goosebumps.
How is skin a sensory organ?
Merkel cells, naked nerve endings into granular layer, nerve endings wrapped around base of hair shaft sense movement of hair, meissners corpuscles (encapsulated nerve endings) in papillary dermis for tactile sensations of pressure and vibration.
What are Pacinian corpuscles?
Encapsulated nerve ending deep dermis and hypodermis, tactile and pressure receptors.