Integument Membranes Bone

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IntegumentMembranesBone
Ex 5-7
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Structure of Skin

• Two Main Layers
• Epidermis
• epithelial layer
• has 4-5 distinct levels
• Dermis
• connective tissue layer
• contains hair, nerve endings, blood vessels,
  glands
• Hypodermis
• not considered part of the skin
• subcutaneous fat and superficial fascia

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Structure of Skin

• Two Main Layers
• Epidermis
• epithelial layer
• has 4-5 distinct levels
• Dermis
• connective tissue layer
• contains hair, nerve endings, blood vessels,
  glands
• Hypodermis
• not considered part of the skin
• subcutaneous fat and superficial fascia

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Epidermis - thin skin

• 4 layers of epidermis
• Stratum Basale (germinativum)
• single row of cells
• undergo mitosis, push cells upwards
• Stratum Spinosum
• several layers of cells
• have a spikey appearance
• Stratum Granulosum
• thin, granular layer of dying cells
• subcutaneous fat and superficial fascia
• Straum Corneum
• layers of dead keratinocytes
• contain keratin and oils

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Epidermis - thin skin

• 4 layers of epidermis
• Stratum Basale (germinativum)
• single row of cells
• undergo mitosis, push cells upwards
• Stratum Spinosum
• several layers of cells
• have a spikey appearance
• Stratum Granulosum
• thin, granular layer of dying cells
• subcutaneous fat and superficial fascia
• Straum Corneum
• layers of dead keratinocytes
• contain keratin and oils

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Epidermis - thick skin

• 5 layers of epidermis in palms and soles
• Stratum Basale
• Stratum Spinosum
• Stratum Granulosum
• Stratum Lucidum
• several layers of pre-dead keratinocytes
• Stratum Corneum
• layers of dead keratinocytes
• contain keratin and oils

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Cell types of the Epidermis

• Keratinocytes (90)
• produce keratin, main structure
• Melanocytes (8)
• produces melanin pigment
• melanin transferred to other cells with long cell
  processes
• Langerhan cells
• from bone marrow
• provide immunity
• Merkel cells
• in deepest layer
• form touch receptor with sensory neuron

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Dermis

• 2 layers of Dermis
• Papillary Layer
• area that contains the dermal papillae
• contains
• loose areolar CT
• blood vessels
• nerve endings (Meissners corpuscle, bare nerves)
• Reticular Layer
• area between papillae and hypodermis
• contains
• dense irregular CT
• hair
• glands (sweat, sebaceous)
• blood vessels, nerve endings (Pacinian corpuscle)

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Structure of Hair

• Specialized keratinocytes packed together
• Root
• bulb
• papilla
• hair growth occurs here
• Shaft
• Follicle
• surrounding tube of epidermis

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Hair Related Structures

• Arrector pili
• smooth muscle in dermis contracts with cold or
  fear.
• forms goosebumps as hair is pulled vertically
• Sebaceous Gland
• oil secreting gland adjacent to hair follicle
• sebaceous follicle is a sebaceous gland that
  secretes onto skin directly

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Fun Things in the Dermis
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Sweat Glands

• Sweat Glands
• located in dermis or hypodermis
• coiled tube
• note numerous parts of gland on cross section
• Two types of sweat glands
• Eccrine glands
• distributed all over body
• secrete sweat which is mostly salt water
• Apocrine glands
• distributed in axillary and genital areas
• secretes a milky protein and fat rich substance
• bacteria love it!

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Other glands

• Ceruminous
• ear wax develops from oil and wax glands
• Mammary
• modified sweat glands that produce milk

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Dermal Sensation

• Meisners Corpuscles
• located in papillae
• responsible for light touch

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Dermal Sensation

• Merkels Disc
• Nerve Ending that cup and monitor pressure on
  cells in stratum basale
• responsible for light touch

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Fingernail

• Anatomy of a nail
• free edge
• nail body
• lunula
• thickened stratum basalis
• eponychium (cuticle)

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skeletal system divisions

• Axial Skeleton
• lie along longitudinal axis
• skull, hyoid, vertebrae, ribs, sternum, ear
  ossicles
• Appendicular Skeleton
• hangs on axial skeleton
• upper lower limbs
• pelvic pectoral girdles

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Types of Bones

• 5 basic types of bones
• long long, slender
• short small, boxy
• flat thin, larger surface area
• irregular variable (vertebrae)
• sesamoid develop in tendons or ligaments
  (patella)
• sutural in joint between skull bones

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Anatomy of a Long Bone

• Diaphysis shaft
• Metaphysis growth plate region, neck between
  epiphysis and diaphysis
• Epiphysis one end of a long bone
• Articular cartilage over joint surfaces acts as
  friction shock absorber
• Medullary cavity marrow cavity

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Epithelial Covering

• Endosteum lining of marrow cavity
• Periosteum tough membrane covering bone but not
  the cartilage
• fibrous layer dense irregular CT
• osteogenic layer bone cells blood vessels
  that nourish or help with repairs

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Epiphyseal Plate

• Epiphyseal Plate
• cartilaginous area where bone growth occurs
• grows at the diaphyseal side
• epiphyseal line is the remnant that is visible in
  the adult

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Types of Bone
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Compact or Dense Bone

• Looks like solid hard layer of bone
• Makes up the shaft of long bones and the external
  layer of all bones
• Resists stresses produced by weight and movement
• main structural unit is the osteon

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Trabecular or Spongy Bone

• Made up of a lattice of bone tissue
• strong yet lightweight
• red marrow
• no osteons

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The Trabeculae of Spongy Bone

• Found in ends of long bones and inside flat bones
  such as the hipbones, sternum, sides of skull,
  and ribs.

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Cell Types of Bone
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Histology of Compact Bone

• Osteon
• Living unit of bone centered around a central
  vessel
• Osteocytes found in spaces called lacunae
• Osteocytes communicate through canaliculi filled
  with extracellular fluid that connect one cell to
  the next cell
• Lamellae rings of matrix between layers of
  osteocytes
• Interstitial lamellae represent older osteons
  that have been partially removed during tissue
  remodeling

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Histology of Compact Bone

• Osteon
• form parallel to direction of force
• can remodel if force directions change
• Lamellae
• calcified matrix between layers of osteocytes
• Interstitial Lamellae
• Central (Haversian) Canal
• Perforating (Volkmans) Canal

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Histology of Compact Bone
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Histology of Compact Bone
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Histology of Compact Bone
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Histology of Compact Bone
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Histology of Compact Bone