integument system pt.1

functions

protection, sensation, excretion of waste, blood reservoir, vitamin D synthesis, regulation of body tmep

sweat glands

evaporative cooling

cutaneous membrane (skin) contains

epidermis and dermis

hypodermis 

subcutaneous layer (just deep to skin, mostly adipose tissue)

epidermis

stratified squamous epithelium (new every 25-45 days)

cell types

Keratinocytes, Melanocytes, Merkel Cells, Langerhan’s cells

melanocytes

produce melanin

merkel cells

spiky hemisphere, associated with sensory nerve ending 

langerhan’s cells

type of macrophage, arise from bone marrow

epidermis major layers (bottom, up)

Stratum basale, Stratum spinosum, Stratum granulosum, Stratum lucidum (in thick skin), Stratum corneum

Stratum basale

mitotically active. contains youngest keratinocytes, melanocytes, and merkle cells 

Stratum spinosum

prickly layer, contains keratinocytes and langerhan’s cells

Stratum granulosum

cells flatten due to accumulation of keratin. nuclei and organelles begin to degerate

Stratum lucidum

presents only in thick skin 

Stratum corneum

horny layer, up to ¾ of epidermis, cornified cells

dermis

connective tissue, has 2 layers papillary layer and reticular layer

papillary layer 

areolar connective tissue, meissner’s corpuscles, dermal papillae (fingerprints) 

Reticular Layer

dense irregular connective tissue, contains Pacinian corpuscles, hair follicles, Sebaceous (oil) glands, sudoriferous (sweat) glands

sebaceous glands

oil

sudoriferous glands

sweat