Lecture 4: Integument Flashcards
Integument
Skin,
Largest organ system in the body
Functions of Skin (6)
Protects underlying tissues and organs,
Excretes salts, water, and organic wastes,
Maintains body temp,
Synthesizes vitamin D3,
Stores lipids,
Detects touch, pressure, pain, and temp through neurons
Two Major Components of Integument
Cutaneous Membrane & Accessory Glands
Cutaneous Membrane
Divided into three layers,
Epidermis,
Dermis,
Hypodermis
Epidermis
Most superficial layer,
All squamous cells at different maturation,
Has 5 layers,
Provides some waterproofing and prevents dehydration
Thin Skin
Covers most of the body,
Has only 4 layers
Thick Skin
Covers the palms of hands and soles of feet,
Has 5 layers of keratinocytes,
Thicker stratum corneum,
Thickness of epidermis is increased, not deeper layers
Keratinocytes
Produce keratin
Avascular
Oxygen and nutrients diffuse from capillaries in the dermis through intercellular fluid
Keratinization
The formation of a layer of dead, protective cells a filled with keratin,
Occurs on all exposed skin surfaces
Stratum Germinativum
Deepest layer of skin,
The germinative layer,
Has many stem cells to replace dead and lost cells from layers above,
Attached to basal lamina (basement membrane) as an anchor
Basal Lamina
A collection of glycoproteins and protein filaments,
Connects epithelial tissue to underlying tissue,
Secreted by epithelial cells,
Superficial (clear) layer touches stratum germinativum,
Deep layer is thicker and more coarse protein filaments
Cellular Connections
Connection of epithelial cells to one another,
Occurs at desmosomes
Epidermal Ridges
Projects down into the dermis from the stratum germinativum
Dermal Papillae
Projects up into the epidermis
Fingerprints
Made by epidermal ridges and dermal papillae,
Small ridges in skin,
Determined genetically,
Provides better grip with more surface area
Specialized cells of stratum germinativum
Merkel cells and Melanocytes
Merkel Cells of Epidermis
Found in hairless skin (palms, soles, forehead),
Respond to touch and release chemicals that stimulate sensory nerves
Melanocytes of Epidermis
Contain the pigment melanin that gives skin color,
Scattered throughout stratum germinative,
Also determined by genetics,
Darker skin is more active melanocytes
_________ break down melanocytes, which fades a tan
Lysosomes
Stratum Spinsosum
Produced by division of stratum germinativum,
8-10 layers of keratinocytes,
Dividing increases the thickness of epithelium,
Contains dendritic cells that are active in immune responses
Dendritic Cells
Take up proteins from bacteria/cancer and ‘deliver’ to WBC to build an immune response
Stratum Granulosum
The ‘grainy’ layer,
3-5 cells thick,
Cells produce protein fibers and flatten,
Dehydrate and die towards the top of the layers,
Plasma membranes become less permeable,
Create tightly interlocked latter of keratin surrounded by keratohyalin
Stratum Lucidum
The 'clear' layer, Found only in thick skin, Covers stratum granulosum, Cells flattened, No organelles, Dead, Filled w/ keratin
Stratum Corneum
The 'horn' layer, Exposed surface of skin, 15-30 layers of keratinized cells, Most superficial, Shed and replaced every 2 weeks, Water resistant
Carotene
Pigment found in orange and yellow vegetables,
Can be altered to make Vitamin A,
Accumulates in epidermal cells,
May cause yellowing of skin
Vitamin D Production
Cells of Stratum germinativum and stratum spinosum produce vitamin d3 in response to uvb radiation,
Vitamin d3 is modified by the liver and kidneys to produce calcitriol
Sun Exposure
Damagers collagen and elastic fibers in dermis, Damages DNA (sunburn, skin cancer)
Dermis
Located between epidermis and subcutaneous layer,
Anchors epidermal accessory structures,
Papillary layer,
Reticular layer
Papillary Layer of Dermis
Consists of loose connective tissue (open framework for movement and shock absorption),
Contains smaller capillaries, lymphatics, and sensory neurons,
Has dermal papillae projecting between epidermal ridges
Reticular Layer of Dermis
Consists of dense irregular connective tissue,
Contains larger blood vessels, lymph vessels, and nerve fibers,
Contains collagen and elastic fibers
Blood Supply in Dermis
Branches of arteries form cutaneous plexus in reticular layer,
Branches of cutaneous plexus form papillary plexus in papillary layer
Contusion in Dermis
Occurs when one or some of these blood vessels rupture
Hypodermis
Subcutaneous Layer Layer in skin for energy storage, Deep to dermis, Stabilizes Skin, Made of Loose Connective Tissue and Adipose Tissue, Very Stretchy
Subcutaneous Fat
Insulates, Shock Absorption (movement and cushion), Energy Storage, White Fat (adipose cells), Brown Fat (Packed with mitochondria that produce heat instead of ATP),
Accessory Organs
Hair,
Sweat Glands,
Oil Glands,
Nails
Hair
Dead cells filled with keratin,
Root and shaft,
3 layers
3 Layers of Hair
Cuticle (outside, hard keratin),
Cortex (middle),
Medula (center ‘tunnel’ that gives hair flexibility, soft keratin)
Hair Follicles
Arrector Pili m. (goose bumps),
Sebaceous Gland (oil gland),
Color (melanin, melanocytes, light hair lacks melanin),
Shape (oval=curly, circle=straight)
Hair Growth Cycle
Each hair grows for 2.5 years before becoming inactive,
When inactive the hair falls out,
Inactivity usually lasts around a year before becoming active again
Sebaceous Glands
Oil glands, Secrete oil into hair follicles, Provides waterproofing, Decreases bacterial infection risk in hair follicle, Holocrine Secretion,
Sebaceous Follicles
Glands not associated with hair,
Located in face, back, chest, genitalia
Sudoriferous Glands
Sweat Glands,
Apocrine and Merocrine,
Both use merocrine secretions,
Apocrine Sweat Glands
Discharge sweat into hair follicles of axilla, nipples, groin,
Begins at puberty,
Strong odor,
Smell created by bacterial secretions after ‘eating’ the sweat
Merocrine Sweat Glands
Most common, Located everywhere that apocrine is not, Discharge onto skin, Cooling to skin, Protection from hazards like bacteria, H20 and NaCl
Ceruminous Glands
Modified sweat glands in external ear,
These secretions combine with sebaceous glands to form cerumen (earwax)
Cerumen
Earwax,
Protects ear canal from foreign objects, insects, and bacteria
Nails
Tightly packed keratin squamous cells,
Dead cells,
Root (fold of epidermal tissue, mitosis occurs, pushes nail to outside of body),
Cuticle,
Color (Lunula=white 1/2 moon, pink=blood capillaries)
