Integumentary System Flashcards Preview

Z Old Anatomy > Integumentary System > Flashcards

Flashcards in Integumentary System Deck (47):
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Functions of the Skin and Hypodermis

- Cushioning & insulation

- Protection

- Excretion (sweat, sebum, milk)

- Prevents water loss

- Temperature regulation

- Calcium/phosphate regulation

- UV protection

- Sensory reception

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Hypodermis

fatty layer deep to dermis

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Epidermis

- outermost layer of skin

- keratinizied stratified squamous epithelium

- 4 main cell types:

  • Keratinocytes
  • Melanocytes
  • Merkel cells (tactile)
  • Langerhans cells ( immune-related, AKA epidermal dendritic cells)

- 5 layers (deepest first):

  • Stratum basale
  • Stratum spinosum
  • Stratum granulosum
  • Stratum lucidum
  • Stratum corneum

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Keratinocyte

- most abundant cell type in epidermis

- arise from stratum basale

- produce keratin

- those at the skin's surface (stratum corneum) are dead

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Melanocyte

- found in Stratum basale

- cells that secrete melanin

- have long, cytoplasmic processes that branch out into above layers, protecting cells below

- sends melanin to keratinocytes, where it is stored around their nuclei to protect their DNA from damage

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Merkel Cells

- oval receptor cells found in Stratum basale

- associated with sense of touch

- AKA tactile epithelial cells

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Langerhans Cells

- AKA dendritic cells

- perform receptor-mediated endocytosis to take up invading antigens and communicate with lymph nodes about it

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The Layers of the Epidermis

- in order from deepest to most superficial:

  • Stratum Basale (or Germinativum)
  • Stratum Spinosum
  • Stratum Granulosum
  • Stratum Lucidum (thick skin only)
  • Stratum Corneum

- Big Stupid Guys Like Coors

 

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Stratum Basale

- AKA Stratum Germinativum

- borders the dermis

- mostly Keratinocytes, some Merkel Cells and Melanocytes

- cells undergo mitosis

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Stratum Spinosum

- cells have thick bundles of intermediate filaments of pre-keratin

- Langerhans cells found here (endocytosis)

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Stratum Granulosum

- contains flattened keratinocytes with keratohyalin granules to promote cross-linking and hydration of keratin and lamellar granules for waterproofing.

 

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Stratum Lucidum

- only found in thick skin of palms and soles of feet

- a few rows of flat, dead keratinocytes

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Stratum Corneum

- outermost layer of epidermis

- varies in thickness

- dead keratinocytes filled with keratin

- protection and water loss prevention

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Melanin

- endogenous pigment produced by melanocytes in the stratum basale of the epidermis

- genetics and sun exposure affect amount produced

- varies in color, yellow, brown or black

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Dermis

- vascular, innervated layer below epidermis

- made of connective tissue (areolar and dense irregular)

- made up of 2 layers:

  • Papillary layer (superficial 20%)
  • Reticular layer (deeper 80%)

- extends upward into epidermis in egg carton-like segments called Dermal Papillae

 

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Papillary Layer of the Dermis

- makes up superficial 20% of dermis

- made of areolar connective tissue with thin collagen and elastic fibers

- dermal papillae project upward toward epidermis, epidermal ridges project downward, which increases surface area for transportation of gases, nutrients and waste between layers

- Meissner's Corpuscles extend into papillae for light touch reception

 

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Reticular Layer of the Dermis

- makes up bottom 80% of dermis

- made up of dense irregular connective tissue

- named "reticular" for its network of collagen & elastic fibers

- site of Lamellated Corpuscles, pressure sensing nerve endings

 

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Cleavage Lines

- less dense regions of collagen in reticular dermis

- useful in surgery because incisions made parallel to cleavage lines heal better

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Tactile Corpuscles

- AKA Meissner's Corpuscles

- located in dermal papillae

- sense light touch

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Lamellated Corpuscles

- AKA Pacinian Corpuscles

- located in reticular layer of dermis

- sense heavier pressures than Meissner's

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Root Hair Plexus

- groups of nerve fiber endings around bulb of hair follicle that sense movement of hair and skin

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Hypodermis

- technically not part of the skin

- contains areolar and adipose tissues

- insulates and anchors skin to underlying structures

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Appendages of the Skin

  1. hair & follicles
  2. sebaceous glands
  3. sweat glands
  4. nails

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Hair

- Long, flexible strands of keratinized cells

- Function: sense, guard, shield, protect

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Hair Follicle

A tubular invagination of the epidermis that contains the hair bulb, hair shaft and hair root

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3 Layers of Hair

  1. Cuticle - scaly-celled, overlapping outer layer
  2. Cortex - middle layer, several layers of flattened cells
  3. Medulla - inner layer, large cells

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Hair Bulb

Deep, swollen end of hair follicle 

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Hair Papilla

Connective tissue that projects up into the bulb, much like dermal papillae into epidermis

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Hair Matrix

Epithelial cells directly above papilla where new hair cells divide rapidly and melanocytes contribute pigment

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Connective Tissue Root Sheath

- outer, dermal layer of sheathing around follicle

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Epithelial Root Sheath

Inner, epidermal layer of sheathing around follicle

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Arrector Pili

- Smooth muscle tissue that extends from the dermal papillae to hair follicles to pull hair upright

- process known as Piloerection

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Hair color

Eumelanin - black and brown hair

Pheomelanin - blonde and red hair

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Sebaceous Glands

- simple, alveolar holocrine glands that empty oily secretions (Sebum) into hair follicles

- found everywhere except palms and soles

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Sebum

- oily secretion from sebaceous glands

- lubricates skin, defends against bacteria, prevents water loss

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Sweat Glands

- AKA Sudoriferous Glands

- two types: Eccrine (or Merocrine) and Apocrine

- sweat is 99% water, salts, acidic excretions

- distributed all over skin

- function as excretory and heat-regulating system

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Holocrine Glands

- entire cell is shed to secrete product

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Eccrine or Merocrine Gland

- secretes product via exocytosis

- coiled simple tubular sweat glands that open to pores on skin surface

- don't extend far into dermis

- produce acidic sweat (pH 4-6)

- especially dense in soles and palms

- narrower lumen than apocrine glands

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Apocrine Gland

- sweat glands that empty into hair follicles of the scalp, neck, axillary and genital areas

- secrete sweat that contains extra lipids and proteins whose breakdown by bacteria is responsible for body odor

- secrete by pinching off of apical cytoplasm with secretions bound within

- wider lumen than eccrine glands

A image thumb
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Ceruminous Glands

- modified sweat glands in the external ear canal

- secretions combine with sebum  to form Cerumen (or earwax)

- Function: waterproofing, eardrum flexibility, block foreign particles, kill bacteria

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Mammary Glands

- modified milk-producing apocrine glands within breasts

- ducts open on nipple

- present in both sexes but functional only in women

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Nails

- scale-like modifications of epidermis

- heavily keratinized

- has distal free edge, visible body and embedded root

- overlapped by fold of skin known as nail fold

- pink due to visible vascularization 

 

A image thumb
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Eponychium

- AKA cuticle

- thick proximal nail fold

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Nail Bed

- extenion of epidermal stratum basale underneath nail body

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Nail Matrix

- analogous to hair matrix

- proximal thickened area of nail bed responsible for growth via cell keratinization 

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Lunula

- AKA White Crescent

- light region of thickened nail matrix