Integumentary System

Thursday, September 22, 2022

Skin is the largest organ

Functions of integumentary: cushions and insulates and is waterproof; protects from chemicals, heat, cold and bacteria; screens UV rays; synthesizes vitamin D with UV; regulates body heat; prevents unnecessary water loss; sensory reception(nerve endings)

Integument = skin

What? - skin, hair, nails, appendages

Where? - most superficial tissue layer of the body

How? - 3 distinct regions: epidermis, dermis, hypodermis

• Epidermis: keratinized stratified squamous epithelium; top
• Dermis: strong, flexible connective tissue; middle
• Hypodermis: adipose (fatty) tissue; below

\
Epidermal cells:

• Keratinocytes: stratified squamous; produce keratin (tough fibrous protein)
• Melanocytes: make dark skin; melanin
• Merkel cells: associated with sensory nerve endings; sensory reception
• Langerhans cells: macrophage- like dendritic cells; white blood cells; eata stuff

Friday, September 23, 2022

Epidermal layer: 5 layers; all are stratified squamous with different functions

Stratum corneum: dead cells; living at one point; horny/rigid  layer; many many layers thick

Stratum lucidum: only on palms and soles; extra layers for increase in toughness; tough dead cells

Stratum granulosum: granules(little dots) give us keratin; flattened keratinocytes

Stratum spinosum: artificial spines; tonofilaments(protein bundles) to resist tension

Stratum basale: basal/basement layer of cells; single row of cells; attached to dermis; youngest cells

CLGSB = come lets get sun-burnt \n

Dermis layer:

Nerves:

• Rich supple/lots; role in sensory reception

Vessels:

• Rich supple/lots; role in temperature regulation

Layers:

• Papillary: top layer; areolar connective tissue(dermal papillae)
• Reticular: bottom layer; network of collagen and reticular fibers

Dermis fibers:

• Collagen: strength and resilience
• Elastic: stretch and recoil
• Reticular: tension lines/lines of cleavage: direction fiber bundle are aligned \n

Dermal cells:

• Fibroblasts: produces extracellular matrix(ecm), collagen, and stroma; ai in wound healing
• Macrophages: search and destroy; identify and destroy harmful organisms
• Mast cells: contain granules that regulate inflammatory responses
• White blood cells(wbc): immune protection against sickness/disease

Monday, September 26, 2022

Hypodermis: “hypo” - below & “dermis” - the skin

Hypodermal cells:

• Areolar tissue: blood vessels; nerves

• Adipose cells: fat-storing cells

  </p>

Accumulation: how organisms store their fat and where exactly they store them

• Female: primarily thickest at breasts, hips, thigh, buttocks
• Male: primarily thickest at neck, arms, lower back, abdomen

\
Glands: one or more cells that make and secrete a particular product; inside and outside of the body

• Endocrine glands: internal secretion - all ductless glands; produce hormones(transported through blood); glands will produce hormones and pop into blood stream
  • Examples: pituitary, ovary, testes, thyroid
• Exocrine glands: external secretion - have ducts
  • Examples: sweat glands, sebaceous glands

\
Exocrine glands: secrete on the surface of the skin

• Merocrine gland: secrets only its secretion product; no part of cell goes with the secretion
  • Sudoriferous/sweat gland: simple, coiled tubes; found everywhere except nipple and external genitalia; secrete hypotonic solution(water, sodium chloride, vitamin c, antibodies, dermcidin(protein that kills bacteria), waste(urea, ammonia, lactic acid)
• Holocrine gland: entire cell is secreted(secretion stays inside the cell)
  • Sebaceous/oil gland: secrete sebum/oil (soften and lubricates; decrease water loss from skin; kills bacteria); blocked sebaceous glands are at first white; if sebum oxidizes, the result is a blackhead; acne is a result of inflamed blackheads, resulting in pus
• Apocrine gland: secretes part of cell with secretion;
  • Ceruminous gland: secrete ear wax; deter insects; block entry of foreign material; dampen loud sounds;
  • Mammary gland: secrete a type of sweat we call milk; contains proteins, lactic acid, water, fats

Friday, September 30, 2022

Exposure to UV light increase melanocyte activity to protect DNA from damage

Melanin:

• Produced by melanocytes: range from yellow/reddish to brown/black
• Skin tone differences not due to amount of melanocytes - due to rate of production vs breakdown of melanin
• Freckles and pigmented moles: local accumulation of melanin

\
Skin pigmentation:

• Carotene: yellow-orange pigment; most obvious in palms and soles of the feet
• Hemoglobin: in red blood cells; reddish pigment responsible for the pinkish hue of the skin

\
Skin pigmentation abnormalities:

• Erythema: reddish skin; fever, embarrassment, hypertension, allergy
• Cyanosis: bluish skin; caused by poorly oxygenated blood
• Pallor: whitish skin; caused by emotion, anemia, low blood pressure
• Jaundice: yellowish skin; liver disorder, bile accumulation \n

Homeostasis imbalance: skin cancer

Most skin tumors are benign and do not metastasize (spread)

3 major types of skin cancer: basal cell carcinoma, squamous cell carcinoma, melanoma

Tuesday, October 4, 2022

Types of hair:

• Vellus hair: pale and fine body hair of children and adult females; “peach fuzz”
• Terminal hair: coarser, longer hair of the eyebrows, eyelashes, and scalp; appear in axillary, pubic, face, chest, arm, and leg regions at puberty; grow in response to stimulating effect of androgens(male sex hormones of which testosteone is most important)

\
Parts of hair:

• Hair/pili: flexible strand of dead keratinized epithelial tissue
• Root: under surface of the skin, keratinization is ongoing
• Follicles: epidermal folds extending into the dermis; little pocket that hair sits in
• Bulb: deep end of the hair follicle
• Matrix: site of cell division where hair grows from
• Hair shaft: exposed portion of hair, keratinization is complete
• Medulla: central core, large cells and air spaces, only part that has soft keratin
• Cortex: surrounds medulla, layers of flattened cells
• Cuticle: formed from overlapping cells; subjected to abrasion, wears away the tip of the shaft leading to “split ends”

\
Hair growth:

• Grows an average of 2 mm per week
• Each follicle goes through growth cycles
  • Active growth phase followed by resting phase (follicles shrink)
  • Start of active phase: new hair pushes out the hold hair(sheds)
  • Cycles of hair follicles aren't synchronized which allows humans to shed only a small percentage of hairs at any one time
  • Terminal hairs are replaced with vellus hairs
• By the age of 60-65, both sexes experience some degree of balding (influenced by genetics)

\
Functions of hair:

• Detects insects
• Guard head from trauma, heat loss, and sunlight(scalp)
• Shield, protection(eyelashes)
• Filter large particles(nose hairs)

\
Nails: scalelike modification of the epidermis on the distal, dorsal surface of the fingers and toes;

• Nails: clear protective covering dorsal surface of distal part of digits
• Nail matrix: thick proximal portion of the nail bed; responsible for nail growth
• Hyponychium: thick region beneath free edge where debris tend to collect
• cuticle(eponychium): proximal nail fold projecting onto the nail body; “on the nail”
• Nail folds: proximal and lateral borders of the nail overlapped by the skin folds

\
Nail appearance:

• Changes can help diagnose different conditions
  • Yellowish: may indicate respiratory/thyroid gland disorder
  • Thickened yellow: usually due to fungus infected nail
• Koilonychia or “spoon nail”
  • Outward concavity of nail (a “dip” in your nail)
  • May indicate iron deficiency
• Beau’s lines/horizontal lines
  • Lines are actress the nails
  • Can be a sign of severe illness affecting whole body(uncontrolled diabetes, a heart attack, chemotherapy)

Wednesday, October 5, 2022

Homeostatic imbalance: burns

• Loss of body fluids: Can lead to renal failure and renal shock/ kidney failure
• Metabolic imbalances: extra foods and nutrients needed to repair tissue
• Microbial infection: bacterial breeding ground

\
Types of burns:

• First-degree: only the epidermis; sunburns; symptoms include redness, swelling, and pain
• Second-degree: epidermis and top of dermis; symptoms mimic first degree burns, but blister also appear(seeping of cytoplasm and interstitial fluid under epidermis)
• Third-degree: entire thickness of the skin is damaged; burned area appears gray-whote, cherry red, or black; there is no initial edema or pain (since nerve endings are destroyed); numbness

\
Rule of nines:

• Counting the number of body regions burned and multiplying by 9 to quickly determine how extensive the burns are; We are “bilaterally symmetrical”
• Easy to divide up the body into eleven sections; Plus 1% for the genital area

\