What does the integumentary system consist of?
skin, hair, nails, glands, some muscles (like pili), sense receptors (nervous), hypodermis
What are the skin layers?
3rd isnt a skin layer
What are the characteristics of epidermis?
Stratified squamous epithelium and avascular
What are the 4-5 strata of the epidermis?
Stratum Basale, Stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
What is the order top down of the strata in the epidermis?
What is stratum Basale? What is it made up of?
- a single row of cells of two cell types
- keratinocytes (90%), this goes through mitosis, makes keratin (a tough protein), pushes cells towards surface as more are produced by mytosis
- melanocytes (10%), produces pigment (melanin) for UV protection. everyone has same amount, but diff amounts of melanin produced and shades of it
- blood (hemoglobin) in dermis can give pink tinge to pale skin
what does stratum Spinosum do?
low levels of mitosis
what does stratum granulosum do?
- no mitosis, last layer of living cells
- contains granules that help produce keratin (strength) and start to produce waterproofing glycolipids (prevents water loss)
What is stratum lucidum?
- dead layer, not visible in thin skin, only thick
- no mitosis, flat cells
What is stratum corneum?
- many layers of flat dead cells filled with keratin (tough protein)
- glycolipids between cells creates waterproof layer (prevents water loss)
- shed on this layer, then replaced from below
what does the dermis contain?
- vascular
- has two sublayers (CT): papillary & reticular layer
- contains blood vessels, nerves, glands, hair follicles, arrector polo muscles
What is the papillary layer of the dermis?
- areolar connective tissue
- vascular
- projects into the epidermis (dermal papillae),
which in thick skin forms the epidermal ridges (fingerprints)
What is the reticular layer of the dermis?
- between papillary layer and hypodermis
- forms most of dermis
- dense regular connective tissue
what layer is this?
The papillary layer of the dermis
what layer is this?
the reticular layer of the dermis
What are the characteristics of thick vs thin skin?
- thick vs thin refers to epidermis, not the dermis
- thin skin: lucidum absent, hair follicles, glands, arrector pilli muscles
- thick skin: palms and soles, lucidum present, no hair, glands, or pilli
What are the 3 derivatives of the epidermal?
hair, nails, skin exocrine glands
What are the parts of hair?
- hair is all dead skin cells
- root, part of hair embedded in skin
- shaft, visible out of skin surface
- hair follicle, surrounds root (made of up pieces)
What makes up the hair follicle?
- epithelial root sheath (several epidermal layers extend into the dermis)
- bulb (expanded region of base of root)
- matrix (single layer of cells derived from basale cells, site of hair growth and melanin for hair colour)
What is associated with each hair follicle?
- outer CT sheath (formed in dermis, holds follicle in place)
- hair papilla (formed in dermis, contains blood for growing hair, extends up from beneath matrix)
- root hair plexus (free nerve endings sensors)
- sebaceous oil gland (opens into follicle)
- arrector pili muscle (smooth muscle, goosebumps)
What are nails? what do they consist of?
- very keratinized epidermal cells
- consists of: nail root (under skin), body (visible), free edge
What are the skin exocrine glands?
sebaceous glands, sudoriferous glands, ceruminous glands, mammary glands
What is the sebaceous gland?
- connects to hair follicles
- secretes sebum (oily, mix of fats, salts, and proteins)
- lubricates hair and skin, antibiotic
What is the sudoriferous gland?
- sweat glands
- secretory portions in dermis of thick and thin skin
- ducts open onto skin surface
- fcns: temp regulation, waste removal, antibiotic action
What are the ceruminous glands?
- modified sweat glands
- in ear canal
- produces ear wax
What are the mammary glands?
- modified sweat glands
- produce milk
What are cutaneous sense receptors? What are the 4 major types?
- sensory receptors are a sensory neuron (part of nervous system)
- specialized cell that responds to stimuli (touch, temp, pain, etc)
- 4 types: touch receptors, pressure receptors, thermoreceptors, nociceptors
Where are the touch receptors?
- free nerve endings in epidermis
- root hair plexuses (nerve endings in end of hair follicle)
- tactile (meissners) corpuscles (sensitive to small touch, CT capsule around nerve ending)
- in dermal papillae
What are the pressure receptors?
- free nerve endings in dermis
- Lamellar (pacinian) corpuscles, CT wrapped nerve endings, deep in dermis or hypodermis
What are the thermoreceptors?
- free nerve endings for temperature
What are the nociceptors?
- free nerve endings for pain
- in the dermis and epidermis, 3rd degree burns take them all out
What is the hypodermis?
- adipose connective tissue below skin that stores (1/2) of bodys adipose tissue (insulation)
- NOT part of the skin
- also called the subcutaneous layer and superficial fascia
What is Albinism?
Lack of melanin production by melanocytes
What is psoriassi?
- Autoimmune disorder that causes accelerated mitosis or keratinocytes in the stratum basale.
- immature keratinocytes accumulate in the epidermis and the stratum corneum fails to shed, resulting in a thick scaley area of the surface of the skin