Chapter 5 - Integumentary System Flashcards
(54 cards)
Integumentary System consists of:
- Skin (aka cutaneous membrane)
- Accessory structures
- Sensory receptors
Skin (Cutaneous membrane) contains:
skin–layers of tissues;
- Epidermis - stratified squamous epithelial; avascular; top 15% of skin; outer layers are “dead cells”; heavily keratinized at surface
- dermis - CT (dense irregular); vascular; bulk of skin–80-85% of skin
Accessory structures (& examples)
structures embedded or sticking out of skin; ex. hair, nails, sebaceous glands, sweat glands
Sensory receptors (& examples)
part of nervous system;
ex. touch, pain/temp, pressure sensors
4 cells that make up Epidermis
- Keratinocyte
- Melanocyte
- Langerhans cells
- Merkel cells
Keratinocyte
most abundant (approx. 90%) cells in epidermis; found in all layers of epidermis; cell make keratin (tough outer surface)
Melanocyte
makes main skin pigments which are called melanin; protects us from UV radiation; found in deepest layer of epidermis–stratum basale
Langerhans cells
immune cells found in epidermis; defense of skin
Merkel cells
touch sensors; found in epidermis
5 Layers of Epidermis (in order–top layer to bottom layer):
- Stratum corneum - top layer
- Stratum lucidum - only present in thick skin; places we rub a lot
- Stratum granulosum - cells are dying & beginning to break down & granules are released
- Stratum spinosum - “living layer” of cells
- Stratum basale - bottom layer; most important layer
Characteristics of Stratum Corneum (Epidermis):
20-30 layers (most layers) of dead, flattened keratinocytes; keratin inside keratinocytes; protect skin, glycolipids in extracellular space waterproof
Characteristics of Stratum Lucidum (Epidermis):
few cell layers (3-5); translucent layer of dead & flattened keratinocytes; thick skin = soles of feet, palms
Characteristics of Stratum Granulosum (Epidermis):
several cell layers, granules accumulate, nuclei & organelles disintegrate in keratinocytes; some granules from keratin & some form water-protection; keratinocytes - half dead cells - dying
Characteristics of Stratum Spinosum (Epidermis):
“living layer” of cells; several cell layers of keratinocytes; keratinocytes contain intermediate filaments; some Langerhans’ cells present in cell layers
Characteristics of Stratum Basale (Epidermis):
most important layer; a SINGLE layer of actively dividing keratinocytes; also contains merkel cells & melanocytes; melanocytes–only present in bottom layer; keratinocytes are formed & divide in this layer; old keratinocytes are pushed up each layer so they get older as they move up each layer
2 Layers of Dermis (in order–top layer to bottom layer):
- Papillary layer - areolar CT; right next to epidermis; richly vascularized
- Reticular layer - dense irregular CT; poorly vascularized
Characteristics of Papillary layer (Dermis):
dermal papillae contain capillary loops, free nerve endings, Meissner’s corpuscles; supplies the epidermis; bumpy thin layer
Characteristics of Reticular layer (Dermis):
collagen arranged in different directions; contain sweat glands, Pacinian corpuscles, hair follicles, sebaceous glands; function: to hold the accessory structures
Hypodermis
layer under the skin; under the dermis; “subcutaneous layer”; mostly adipose tissue; vascularized; mainly fat cells–nutrient storage & insulation
Papillary layer (Dermis)
dermal papillae–hill or mound of CT
Capillary loops
thin blood vessels where exchanges can take place; holds Oxygen & nutrients & supplies it to epidermis; papillary layer (dermis)
Free nerve endings
pain & temp sensors; able to sense extreme temp that are likely to damage skin; papillary layer (dermis)
Meissner’s Corpuscles
touch sensors; papillary layer (dermis)
Reticular layer (Dermis)
doesn’t really help epidermis for blood supply bc further away & dense (so not many blood vessels); a lot of of accessory structures found here
