Integumentary System

• The integumentary system consists of the skin and its appendages, including hair, nails, and glands
• Functions of the integumentary system:

  • Sensation
  • Heat regulation
  • Absorption
  • Protection
  • Excretion
  • Storage of fats
• Friction blisters are caused by continuous rubbing or pressure on the skin, usually occurring on the feet
• Corns and calluses are hard, painful areas of skin that develop in response to pressure or friction, often on the feet
• The dermis has two main layers:

  • Papillary layer: made of loose, areolar connective tissue and projects into the epidermis
  • Reticular layer: consists of dense, irregular connective tissue and is well vascularized with a rich sensory and sympathetic nerve supply
• Arterio-venous anastomoses (AVAs) are direct connections between small arteries and small veins, aiding in heat transport from the body core to surface areas. They regulate blood pressure, blood flow, and temperature and conservation of body heat
• Peripheral cyanosis is a bluish discoloration of the hands or feet due to low oxygen levels in the blood
• Jaundice is characterized by yellowing of the skin and eyes due to excess bilirubin in the blood
• Erythema is redness of the skin or mucous membranes caused by increased superficial capillaries' blood flow(hyperemia), often seen with skin injury, infection, or inflammation
• Selected disorders of the integumentary system include:

  • Albinism: inability to produce melanin
  • Vitiligo: melanocyte in certain aeas lose the ability to produce melanin
  • Stretch marks: occur when skin is stretched
  • Melanoma: cancer that develops from the melanocyte
• Wounds can be classified as open or closed:

  • Closed wounds do not break the skin's surface, like bruises
  • Open wounds involve a break in the skin, caused by various objects or trauma
• Closed wounds can include:

  • Contusions (bruises)
  • Hematomas
  • Seroma
  • Crush injuries
• Wound healing is a complex process involving four phases: Hemostasis, Inflammation, Proliferation, and Maturation
• Types of Human Hair:

  • Lanugo: Fine, downy, unpigmented hair that appears on the fetus in the last three months of development
  • Vellus: Fine, pale hair that replaces lanugo by the time of birth, making up two-thirds of women's hair and one-tenth of men's hair
  • Terminal: Longer, coarser, and more heavily pigmented hair located in eyebrows, eyelashes, scalp, and forms axillary and pubic hair after puberty
• Alopecia areata:

  • An autoimmune disease with non-scarring hair loss in single or multiple areas of the scalp, face, or body
  • Includes alopecia totalis (complete loss of hair on the scalp) and alopecia universalis (loss of hair in the entire body)
• Hirsutism:

  • Excessive body hair in men and women on parts of the body where hair is normally absent or minimal, such as on the chin, chest, face, or body
• Nails:

  • Horny covering protecting the upper surface of the tip of the finger and toe in humans and other primates
• Cutaneous Sensory Receptors:

  • Meissner's corpuscle: detect light motion against the skin, detect deep pressure, high-frequency vibration
  • Ruffini corpuscle: detect deep pressure, stretch
  • Free nerve endings: integrated with sensations including pain, heat, cold, and touch
  • Merkel cells: function as receptors for sustained light touch and sensing an object's texture
  • Root hair plexus: detect movements of hair
  • Pacinian corpuscle: detect deep pressure, highfreq. vibration
  • Krause end bulbs: found primarily in the skin of penis and clit where they sense low freq vib.
• Glands:

  • Sebaceous Glands: secrete oily or waxy matter called sebum to lubricate and waterproof the skin and hair
  • Ceruminous Glands: specialized sweat glands located in the external auditory canal
  • Mammary Gland: enlarged and modified sweat glands characteristic of mammals, functional in women during childbearing years
  • Sudoriferous/Sweat Glands:
  • Eccrine Sweat Glands: distributed all over the body, discharge secretions directly to the skin surface to regulate body temperature
  • Apocrine Sweat Glands: found in armpits, produce viscous secretion that ends in hair follicle canals after puberty
• Key Clinical Terms:

  • Acne: long-term skin disease caused by clogged hair follicles with dead skin cells and oil, characterized by blackheads, whiteheads, pimples, oily skin, and possible scarring
  • Athlete's Foot: fungal infection that usually begins between the toes, causing itching, stinging, and burning
  • Boil: localized skin infection starting in a hair follicle or oil gland, characterized by reddening, tender lump, and presence of pus
  • Decubitus Ulcer: pressure ulcer, bedsore, open wound on the skin from continual pressure
  • Wart: small growth with a rough texture caused by viruses in the human papillomavirus (HPV) family
• Cells of the Epidermis

  • stem cells
  • keratinocytes
  • melanocytes
  • tactile cells
  • dendritic cells
  • langerhans cells
  • merkel cells
• Stem cells

  • give rise to keratinocytes
  • found in the deepest layer of epidermis
• Keratinocytes

  • make up majority of epidermal cells and synthesize keratin
• Melanocytes

  • only found in the deepest layer and synthesize melanin
• Tactile cells

  • found in the deepest layer and have touch receptors associated with nerve fibers
• Dendritic cells

  • macrophage like and igrated from bone marrow
  • guard against pathogens
• Langerhans cells

  • recognize, phagocytose, and process foreign antigens and then present them to T lymphocytes for an immune response.
• Merkel cells

  • found in the stratum basale
  • most abundant in the fingertips
  • function as mechanoreceptors for cutaneous sensation
• Open wounds classification

  • abrasion
  • laceration
  • avulsion
  • incision
  • puncture
  • amputation
• Abrasion

  • superficial wounds in which the uppermost layer of the skin is scraped off
• Laceration

  • irregular tear like wounds caused by some blunt trauma
• Avulsion

  • an injury in which a body part is torn off due to either trauma or surgery
• Incision

  • A wound caused by a clean, sharp-edged object such as a knife, a razor or a glass splinter.
• Puncture

  • caused by an object puncturing the skin such as a nail or needle
• Amputation

  • refer to the removal of a limb due to trauma, medical illness, or surgery
• Stages of hair growth

  • Anagen (growing phase)
  • Catagen (transition phase)
  • Telegen (resting phase)
  • Exogen (shedding phase)
• Nail disorders

  • Beau's lines
  • Clubbing
  • Koilonychia
  • Leukonychia
• Beau's lines

  • refer to depressions that run across fingernail which can be a sign of malnourishment and other conditions
• Clubbing

  • Thickening and curving of nail around fingertips, which can be the result of low oxygen in the blood and is associated with cardiovascular diseases, inflammatory bowel disease, liver disease and others
• Koilonychia

  • condition where fingernails have raised ridges and scoop outward, like spoons.
  • it can be a sign of iron deficiency anemia, heart disease and other medical condition.