Chapter 5 Flashcards
Functions of the Integument system?
PROTECTION
PROTECTION: 1. CHEMICAL BARRIER: Acid mantle : low pH of sweat Antibacterial agents Melanin: hinders UV damage
- PHYSICAL BARRIER:
- Continuity of skin with keratinized cells
- Extracellular glycolipids
- Protection from harmful chemicals, toxins and microbes
- Prevents water loss - BIOLOGICAL BARRIER:
- Epidermal dendritic cells: activate immune response to foreign substance
- Dermal macrophages: phagocytosis
Functions of the Integument system?
REGULATION OF BODY TEMP.
- Sweat Glands:
- Insensible glands (500 mL day)
- Sensible glands (12L day) - Dilation/constriction of blood vessels in skin
Other functions of the integument system?
III. Cutaneous Sensation
IV. Metabolic Functions
- Vitamin D synthesis
V. Blood reservoir
Structure of the integument
EPIDERMIS
- Stratified squamous
- Not vascularized
- Mitotic
DERMIS:
- Bulk of skin
- Vascularized
SUBCUTANEOUS LAYER:
- NOT part of skin
- Mostly adipose and areolar CT
- Cushions, insulates, anchors
Keratinization
- Cells flatten and nuclei and organelles disintegrate
- Accumulate keratohyaline and lamellar granules
- Keratohyaline granules to keratin
- Lamellar granules to extracellular glycolipids
Layers of the epidermis
Thin skin has 4 layers
Thick skin has 5 layers
STRATUM BASALE:
- Bottom layer, one row of cells, highly mitotic
- Keratinocytes begin here
- Melanocytes: synthesize melanin
STRATUM SPINOSUM:
- Keratinocytes: geometric shaped TO flattened
- Desmosomes: evident here but throughout epidermis
Epidermal dendritic cells
STRATUM GRANULOSUM:
- Last layer of living cells
- Keratinization process begins
STRATUM LUCIDIUM:
- Visible only in thick skin (palms, soles)
- Dead cells
STRATUM CORNEUM:
- Dead cells filled with keratin protein
- Glycolipids between cells
- “Cornified” cells continually slough off
- Protection against abrasion and penetration
Layers of the dermis:
PAPILLARY LAYER
- Thin
- Areolar CT
- Dermal macrophages and other immune cells patrol
- Projections of dermis into epidermis: dermal papillae
- Nervous structures present to sense pain and touch
Tactile corpuscles
Meissner’s corpuscles
Layers of the dermis:
RETICULAR LAYER
- Dense irregular CT
- 80% of dermis thickness
- *Reticular does NOT indicate high abundance of reticular fibers
- Collagen + elastic fibers giving skin tensile stretch and stretch-recoil properties
Types of sweat glands
- Eccrine:
- merocrine secretion (exocytosis)
- More numerous than 2nd type
- Duct leads to pore on surface
- Regulation of body temp
- Merocrine secretion (exocytosis)
- Hypotonic filtrate of blood
- located everywhere on body - Apocrine:
- Axillary and anogenital areas
- Secretion is thicker containing lipids and proteins
- Merocrine secretion (exocytosis)
- Ducts empty into hair follicles
- NOT for temp regulation
- may act as sexual scent glands
What is merocrine secretion?
A cell is classified as merocrine if the secretions of that cell are excreted via exocytosis from secretory cells into an epithelial-walled duct or ducts and then onto a bodily surface or into the lumen.
Sebaceous (Oil) Glands
- Cover surface of body (a few exceptions)
- Vary in size
- Usually empty into hair follicle
- Sebum: oily secretion
- Lubricates hair + softens skin
- Holocrine secretion
Burns:
- Causes: heat, electricity, radiation, chemicals
- Denature proteins to cell death
- Classified by severity (depth)
Severity of Burns:
FIRST DEGREE:
- only epidermis
- Redness, pain, slight edema
- Heals 3-5 days
SECOND DEGREE:
- epidermis and upper dermis
- Redness, pain, blisters
- Heals 2-4 weeks
- May not scar
- Need to prevent infection
THIRD DEGREE:
- entire thickness of skin
- Nerve endings destroyed
- Severe fluid loss
- Scarring
- Skin grafts
- Initial threat to life in 3rd degree burn*:
- Loss of body fluids LEAD TO Dehydration and electrolyte imbalance LEAD TO Renal failure and circulatory shock
- Treatment: replace fluids
- After initial crisis: infection main threat
Skin cancer;
Main cause: overexposure to UV radiation in sunlight
- Basal cell carcinoma
- Squamous cell carcinoma
- (Malignant) Melanoma
Types of skin cancer;
Basal Cell Carcinoma:
- Least malignant, most common
- Stratum Basale cells proliferate
- Surgical excision
Squamous cell Carcinoma:
- Second most common
- Keratinocytes of stratum spinosum
- Can metastasize if not removed
- Radiation or surgical removal
Melanoma:
- Melanocytes
- Highly metastatic and resistant to chemotherapy
- 2-3% of skin cancers
- Surgical excision and immunotherapy
