BIO 105: A & P I - Integumentary System

Flashcards for BIO 105: A & P I lecture notes covering the integumentary system and related pathologies.

Integumentary System (Skin)

The largest organ in the body, providing a protective boundary between the body’s internal environment and the external world.

Functions of the Skin - Protection

Protection from microbes, abrasions, heat, chemicals, dehydration, UV light, and foreign invaders.

Cutaneous Sensations

Touch, pressure, vibration, tickling, warmth, coolness, and pain.

Excretion

Elimination of substances from the body, such as sweat, salts, carbon dioxide, ammonia, and urea.

Absorption

Passage of materials from the external environment into body cells; includes fat-soluble vitamins, drugs, and toxic materials.

Synthesis of Vitamin D

Requires activation of a molecule in the skin by UV rays; final activation occurs in the liver and kidneys to produce calcitriol.

Blood Reservoir (Skin)

Skin houses an extensive network of blood vessels that carry 8-10% of total blood flow in a resting adult.

Thermoregulation (Skin)

Regulating body temperature through sweat and adjusting blood flow.

Epidermis

Outer, thin layer of the skin, avascular, composed of keratinized stratified squamous epithelium.

Principal Cell Types in Epidermis

Keratinocytes, melanocytes, Langerhans cells, and Merkel cells.

Keratin

Tough, fibrous protein that protects skin and underlying tissues from abrasions, heat, microbes, and chemicals; releases water repellent sealant.

Melanin

Pigment that contributes to skin color and absorbs damaging UV light.

Langerhans Cells (Dendritic Cells)

Arise from red bone marrow and participate in immune response.

Merkel Cells (Tactile Cells)

Deepest layer of epidermis, part of sensory response (light touch).

Layers of the Epidermis

Stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale.

Stratum Corneum

Average of 25-30 layers of flattened, dead keratinocytes; cells are continuously shed and replaced.

Stratum Lucidum

Translucent layer only found in areas of thick skin (hands, feet); 3-5 layers of flattened, clear, dead keratinocytes.

Stratum Granulosum

3-5 layers of flattened keratinocytes that are undergoing apoptosis.

Stratum Spinosum

8-10 layers thick, rich in RNA for protein synthesis needed to make keratin.

Stratum Basale

Single layer of cells which undergo mitosis; layers migrate superficially until they are shed (about 35 days).

Dermis

Dense irregular connective tissue and areolar connective tissue with collagen and elastic fibers; contains fibroblast, macrophages, and adipocytes.

Regions of the Dermis

Papillary region and reticular region.

Papillary Region

Thin layer of areolar connective tissue containing Meissner corpuscles and dermal papillae.

Meissner Corpuscles

Tactile receptors sensitive to touch.

Dermal Papillae

Ridges in dermis projecting into epidermis to create fingerprints; function to allow grip.

Reticular Region

Thick layer of dense irregular connective tissue containing blood vessels, nerves, hair follicles, sebaceous and sudoriferous glands, and arrector pili muscle.

Hypodermis (Subcutaneous Layer)

Deep to dermis, made of areolar and adipose connective tissue.

Burns

Tissue damage caused by excessive heat, electricity, radioactivity, or corrosive chemicals that denature proteins in the skin.

Decubitus Ulcers (Pressure Ulcers/Pressure Sores)

Vascular skin disorder caused by continuous pressure on the skin leading to decreased blood flow; common in geriatric population and those with impaired mobility.

MRSA (Methicillin-resistant Staphylococcus aureus)

Antibiotic-resistant staph infection; at risk: youth, elderly, athletes, those with weakened immune systems, living in crowded conditions, and healthcare workers.

Warts

Caused by HPV (human papillomavirus) through direct contact; usually benign but can be malignant.

Fever (Febrile State)

High body temperature associated with a systemic inflammatory response.

Heat Exhaustion

The body loses a large amount of fluid resulting from heat-loss mechanisms; warning signs include heavy sweating, muscle cramps, weakness, and dizziness.

Heat Stroke (Sunstroke)

Severe condition resulting from the inability of the body to maintain a normal temperature in an extremely warm environment; body temperature above 105 degrees; warning signs include hot dry skin, no sweat, headache, rapid pulse, hallucinations, and confusion.