A&P 1 Unit 6 (Lab) [Integumentary System] Flashcards
Integumentary System
Composed of:
- Skin: Body’s largest organ
- Accessory structures:
- Hair
- Nails
- Skin Glands
Functions of Skin
-
Protection
- Prevents fluid loss, abrasions and other wounds, microbial entry
-
Body temperature homeostasis
- Evaporative cooling sweat
-
Excetion
- Glands excrete (get rid of) small quantities of salts, water, organic wastes
-
Begins the synthesis of vitamin D
- Stimulated by exposing skin to UV light. (ex. sunshine)
- Liver and kidneys complete synthesis of physiologically active form.
- Vitamin D is required for calcuim sbsorption from gastrointestinal tract.
-
Sensory Detection
- Pain, temperature, touch, and pressure
Skin contains all four primary tissues:
- Epithelial
- Connective
- Muscle
- Nervous
Epithelial Tissue
- Covers surfaces
- Lines structures
- Forms secretory glands
- Exocrine Glands
- Endocrine Glands
Exocrine Glands
Secretion travels through duct to reach an external surface (of cell, or body) [ex. sweat glands]
Endocrine Glands
Secrete hormones into interstitial fluid (NO duct is used)
Epithelial Tissue Naming
- Describes shape of cells, and whether there are layers of cells
- Cell Shape Terms:
- Squamous
- Cuboidal
- Columnar
- Cell Layer Terms:
- Simple
- Stratified
- Pseudostratified
Squamous
Thin, flat cells
Cuboidal
Cell height and width about the same
Columnar
Tall, narrow cells
Apical Surface
Faces body’s exterior, or an internal space
Basal Surface
Attached to the deeper, adjacent connective tissue
Simple Layer
Cells line up in single layer
Stratified Layer
Multiple layers of cells (stacked)
Pseudostratified Layer
Cells are different heights; tissue appears layered, but it is not!
Other Characteristics of Epithelia
- Avascular
- NO blood vessels
- Epithelial cells rely on diffusion of O2 and nutrients from adjacent, vascular tissue.
- Cells are vary close together
- Secure connections between cells
- Little extracellular material between cells
Connective Tissue
- Most diverse primary tissue
- Inclubes bone, cartilage, blod, adipose, and dermis (deep layer) of skin.
- Cells are widely spaced
- Large amount of extracellular material
- In general, called the matrix
- Contains protein fibers (ex. collagen in dermis)
Epidermis
- epithelial tissue
- no blood supply
Dermis
- Connective tissue
- Blood Supply
Hypodermis
Subcutaneous Tissue (deep to skin)
Connects the skin to the underlying tissues and is not considered part of the integument.
Specialized Skin Structures
- Sweat Glands
- Sebaceous (oil) Glands
- Arrector Pili Muscles
- Sensory Receptors
Sweat Glands
- Eccrine
- Exocrine glands; salty solution; evaporation→ temperature regulation
- Apocrine
- Exocrine glands; viscous; bacteria breakdown→ odor; pheromones?
Sebaceous (oil) Glands
Exocrine glands; empty into hair follicle; moisture; antibacterial
Arrector Pili Muscles
Smooth muscle; associated with hair follicle; pull hair “on end)
Sensory Receptors
- Free Nerve Endings- Detect tissue damage via chemicals released (pain, itch)
- Mechanoreceptors- Detect mechanical/physical stimuli (touch, pressure, temperature)
Layers of Epidermis
- Stratum Corneum
- Stratum Lucidum*
- Stratum Granulosum
- Startum Spinosum
- Stratum Basale
- Dermis**
Stratum Corneum
Dead, flattened sacs of keratin
Stratum Lucidum
Dead; visible only in thick skin
Stratum Granulosum
Accumulating the protein keratin
Stratum Spinosum
Thorny appearance is due to slide preparation
Stratum Basale
Deepest; contains mitotic cells
One roll of cells
Cell Types in Epidermis
- Ketinocyte
- Melanocytes
- Langerhans Cell
- Merkel Cell
Keratinocytes
Sythesize the protein keratin, making the epideremis waterproof and strong
Melanocytes
Synthesize the pigment melanin; protects keratinocyte nuclei from ultraviolet (UV) light
Langerhans Cells
Phagocytic cells thath protect the epidermis by engulfing and digesting microbes (“phago” means “eating”)
Merkel Cells
Communicate with neurons, to convey the senses of light touch and pressure.
Melanin
Accumulates on the “sunny side” of the keratinocyte nulceus, protecting DNA against some (not all) UV damage. UV light is stil damaging to skin! (Melanocytes)
UVA Rays
Aging
UVA rays penetrate deeply into skin. They are present year-round, all day, and pass through clouds and glass.
UVB Rays
Burns
ABCD of Melanoma Detection
- Asymmetry
- Border
- Color
- Diameter
Asymmetry (melanoma)
When half of the mole does not match the other half
Border (melanoma)
When the border (edges) of the mole are ragged or irregular
Color (melanoma)
When the color of the mole varies throughout
Diameter (melanoma)
If the mole’s diameter is larger than a pencil’s eraser
Jaundice
Yellowing of skin
Yellowing is from accumulated bilirubin in the skin, often caused by liver and gallbladder disorders.
Cyanosis
Bluish skin, lips, nail beds
Psoriasis
Keratinocytes migrate to the stratum corneum too fast, forming red, scaly patches.
The skin synthesizes an abnormal form of keratin.
The Dermis Contains Two Layers:
- Papillary Layer
- Reticular Layer
Papillary Layer
Contains ‘fingers” called dermal papillae, made of areolar connective tissue.
(Supplies the avascular epidermis)
Reticular Layer
Contains mostly dense irregular connective tissue, and a small amount of adipose tissue (not visible here)
Areolar Connective Tissue
Also called Loose Connective Tissue
- Found in the papillary region of the dermis
- Protein fibers are collagen and elastic
- Collagen gives STRENGTH
- Elastic gives STRETCH and RECOIL
Dense Irregular Connective TIssue
- Found in reticular layer of dermis
- Densely organized bundles of collagen
- Collagen fibers oriented at amny different angles
- Allows dermis to resist tension and pull from many different directions
Adipose Tissue
Located in the deep dermis (little) and in the hypodermis (most)
Adipose tissue connects tissue together, pads, insulates, and stores energy in the form of triglyceried molecules
First Degree Burns
Damage the superficial epidermis
Second Degree Burns
Damage the entire epidermis, and may also damage a portion of dermis (note blistering)
Third Degree (Full-Thickness) Burns
Destroy the epidermis and dermis. Damage extends into subcutaneous tissues.
Decubitus (Pressure) Ulcers
Also called “bed sore”
Has 4 stages.
Avascular
- NO blood vessels
- Epithelial cells rely on diffusion of O2 and nutrients from adjacent, vascular Pssue
Thick Skin
Palms & Soles
Thin Skin
Everywhere else (may have hair)
Keratin
Keratin is the key structural material making up the outer layer of human skin. It is also the key structural component of hair and nails. (Keratinocytes)
Vitamin D
Helps with absorption of calcium. Sunlight is needed for synthesis.
Skin, Liver, & Kidneys for the synthesis.
Eccrine Sweat Glands
They produce a clear, odorless substance, consisting primarily of water and NaCl (note that the odor from sweat is due to bacterial activity on the secretions of the apocrine sweat glands).
Apocrine Sweat Glands
is a sweat gland composed of a coiled secretory portion located at the junction of the dermis and subcutaneous fat, from which a straight portion inserts and secretes into the infundibular portion of the hair follicle.[7] In humans, apocrine sweat glands are found only in certain locations of the body: the axillae (armpits), areola and nipples of the breast, ear canal, eyelids, wings of the nostril, perianal region, and some parts of the external genitalia.
Meissner’s (Tactile) Corpuscles
They are a type of nerve ending in the skin that is responsible for sensitivity to light touch. In particular, they have highest sensitivity (lowest threshold) when sensing vibrations lower than 50 Hertz. They are rapidly adaptive receptors.
Pacinian (Lamellated) Corpuscles
They are nerve endings in the skin responsible for sensitivity to vibration and pressure. Vibrational role may be used to detect surface, e.g., rough vs. smooth. Lamellar corpuscles are also found in the pancreas, where they detect vibration and possibly very low frequency sounds.
Explain how the living cells of the epidermis receive oxygen and nutrients
All epithelial tissue requires oxygen and nutrients to be delivered from the deeper tissues. In the case of the epidermis, this deeper tissue is the DERMIS. Are close enough to the blood supply in the dermis to get the adequate oxygen and nutrients for survival.
