Skin (Integumentary System) Flashcards
What are the functions of the integumentary system?
- protects your inner organs and it is in need of daily care and protection to maintain its health.
- Protects the body
from: invasion by microorganisms and other environmental factors,
Wear and tear from contact with grit, microbes, or harmful chemicals,
DNA damage caused by UV radiation - Prevent dehydration: layers of keratin and glycolipids in the stratum corneum
- Acts as a sensory organ
- Maintains temperature and electrolyte balance
- Synthesizes vitamin D
- Underlying hypodermis stores fats, protects underlying structures, provides insulation
Overview of the integumentary system
- Composed of skin and its accessory structures
- 16 percent of body weight and covers an area of 1.5 - 2 m2 in an adult human body
- largest organ system in the human body
What is the structure of the integumentary system?
Divided into three main regions
Epidermis: avascular, thinnest, most superficial layer
Dermis: well-vascularized, contains components associated with skin function
Hypodermis: well-vascularized, loose connective tissue which anchors it to underlying structures
made of multiple layers of cells and tissues
Communicates with the brain via sensory, autonomic and sympathetic nervous systems
In the epidermis what is the difference between thick and thin skin?
Thick skin:
Contains 5 layers: includes stratum lucidum
Appearance: Friction ridges (tire treads, prints)
Function: sensation, manipulation of objects
Location: palms of hands and soles of feet
Thin skin:
Contains 4 layers: stratum lucidum is absent
Appearance: Smooth with irregular grooves
Function: Normal skin function
Location: found in most locations throughout the body
What cells are in the epidermis?
Basal cells, Keratinocytes, Merkel cell, Melanocytes and Langerhans cells (dendritic cells)
What are the functions and locations of the cells in the epidermis?
Basal cells: cuboidal stem cell that produces keratinocytes
Location: Stratum basale
Keratinocytes: cells that manufactures and stores the protein keratin and water-repelling glycolipid that helps prevent water loss from the body
Location: stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
Merkel cell: touch receptor for sensory nerves, especially abundant on surfaces of hands and feet
Location: Stratum basale
Melanocytes: cell that produces the melanin pigment, which gives hair and skin its color, and protects the epidermis from ultraviolet (UV) radiation damage
Location: Stratum Basale
Langerhans cells (dendritic cells): Macrophages that destroy bacteria, foreign particles, and damaged cells Location: Stratum spinosum
Layers of the epidermis (top-bottom)
Stratum Corneum, Stratum Lucidum, Stratum Granulosum, Stratum Spinosum and Stratum Basale (Stratum germinative)
Stratum Basale (stratum germinativum)
single layer of stem cells that constantly produces new cells which is then pushed towards to surface
attaches the epidermis to dermis via basal lamina, basement membrane intertwining collagen fibers
Stratum Spinosum
looks spiny due to presence of desmosomes with interlock with each other and strengthen the bond between the cells
8-10 layers of keratinocytes rich in RNA to produce keratin
Stratum Granulosum
grainy appearance due to accumulation of keratin granules
3-5 layers of flat cells with thicker cell membranes: nuclei and other organelles disintegrate as cells die
Stratum Lucidum
smooth, seemingly translucent thin layer
found only in the thick skin of palms, soles, and digits
Stratum Corneum
15 - 30 layers of dry, dead cells filled with keratin.
most superficial layer: exposed to external
Melanocytes
cells that produce melanin
Melanin
pigments that give skin its color
Melanosomes
vesicles of melanin produced by melanocytes
Properties of Melanin
- Provide color to hair and skin, and protects
- DNA damage caused by ultraviolet radiation.
- Melanin occurs as eumelanin (black and brown) and pheomelanin (red).
- Dark-skinned individuals produce more melanin than those with pale skin.
- Too little melanin can cause DNA damage of epidermal cells and folic acid destruction
- Too much melanin can reduce vitamin D production, an important nutrient involved in calcium absorption
Explain how tanning occurs over the course of seven days
- Prolonged exposure to ultraviolet (UV) radiation in sunlight
- Melanocytes increase melanin production
- skin color darkens
melanin in nuclear cap absorbs UV radiation before it reaches DNA. Increased apoptosis of UV damaged cells - If cells are NOT protected by melanin, UV radiation reaches the nucleus to cause severe damage, eg skin cancer
Why do tans not last?
- Melanosomes are eventually destroyed by fusion with lysosomes;
- Melanin-filled keratinocytes in the stratum corneum eventually slough off
What is the location and structure of the Dermis?
Location: deep to the epidermis
Structure: 2 layers of connective tissue of an interconnected mesh of elastin and collagenous fibers with fibroblasts, blood and lymph vessels, adipocytes, phagocytes, nerves, hair follicles, sweat glands, touch receptors (Meissner corpuscles)
Papillary Layer: superficial layer of loose, areolar connective tissue which forms finger-like dermal papillae to increase connection strength with epidermis
Reticular Layer: Deeper, thicker layer of dense, irregular connective tissue which provide elasticity, structure and tensile strength. Collagen binds to water to keep the skin hydrated
What is the location, structure, and function of the Hypodermis (subcutaneous layer or superficial fascia)?
Location: lies directly below dermis to connect skin to underlying fascia (fibrous tissue) of bones and muscles. Not strictly a part of skin
Structure: well-vascularized, loose, areolar connective tissue and adipose tissue
Function: fat storage, insulates and cushions the integumentary system
What is the structure and function of hair?
Structure: keratinous filament growing out of the epidermis made of dead, keratinized cells.
Functions: protection, sensory input, thermoregulation, and communication.
protects the skull from the sun, traps and excludes particles containing allergens and microbes.
hair root plexus senses air movement or other environmental disturbances
arrector pili (smooth muscle) connected to hair root contracts to cause goosebumps which makes the external hair shaft “stand up” and trap a layer of air to add insulation.
What is the structure and function of nails?
Structure: nail body is formed from densely packed dead keratinocytes and rests on the nail bed
Functions: protects tips of fingers and toes from maximum mechanical stress due to their location (farthest extremities). Also forms a back-support for picking up small objects with the fingers.
Sweat glands are a type of…
Merocrine exocrine gland
What are the different types of glands and their locations?
Sudoriferous glands: produce watery sweat to cool the body (thermoregulation)
Eccrine sweat gland: releases sweat via pores
Type of sweat: hypotonic sweat
Location: all over the body, mostly associated with hair follicles
Apocrine sweat gland: releases sweat into hair follicles.
Type of sweat: Thicker sweat due to organic compounds which can be decomposed by bacteria and smell
Location: hair follicles in densely hairy areas (armpits and genital regions)
Sebaceous Gland: produces lipid sebum onto the skin surface.
Function: lubricates and waterproofs skin and hair, antibacterial properties
Location: all over the skin’s surface, abundant on palms, soles, forehead.
