Ncm 104 Lecture Notes

Only available on StudyMode
  • Download(s) : 303
  • Published : November 24, 2012
Open Document
Text Preview
NCM 104
DERMATOLOGIC DISORDERS

I. REVIEW OF THE INTEGUMENTARY SYSTEM

SKIN – also known as the integument which means covering
- largest organ system
- barrier between external and internal environment

FUNCTIONS OF THE SKIN

1) Protection
- protects from trauma (Mechanical, Radiation, Thermal)
- thickened skin on palms and soles provides additional covering against trauma r/t constant use
- Intact skin - primary defense (prevents invasion of microorganisms)
- secretions(from sebaceous gland) are oily and slightly acidic (prevents/limits the mult. of mcgs) 2) Maintenance of Homeostasis
- prevents excessive loss of water and electrolytes
3) Thermoregulation
- affected by:
> production of perspiration (dehydration fever)
> activity
> constriction (↓ dissipation of heat) and dilation of blood vessels
> external BT ↔body’s core temperature
4) Reception of stimuli
- area in the brain – SOMATOSENSORY CORTEX
- abundance of free nerve endings and receptors
* NOCICEPTOR - pain
* END-ORGAN OF RUFFINI/PACINIAN CORPUSCLE - pressure
* MECHANORECEPTOR - machanical
* MEISSNER’S CORPUCLES (MERKEL DISCS/CELLS) - touch
5) Synthesis of vitamin D
- helps the uptake of Ca2+ and PO4 in intracellular level
- with the aid of sunlight activates Vitamin D to D3 (Cholecalciferol) 6) Immunity/processing of antigenic substances
- immunologically mediated defenses against microorganisms
Ex. Langerhans cells
Keratinocytes
7) Provide an outward appearance or cosmetic adornment
- acceptance of the appearance of the skin, hair, or nail is critical to psychosocial being 8) Excretion
- skin has a vital role in elimination of Na+ and H2O for homeostasis (maintaining balance in the internal environment)

STRUCTURES OF THE SKIN

LAYERS OF THE SKIN

1) EPIDERMIS – avascular in nature
- Thickness: 0.04 mm (eyelids- thinnest) to 1.6 mm (palms and soles- thickest)

4 Cell types of the Epidermis
a) Keratinocytes - 95%
- Produces Keratin - insoluble protein
- helps create a waterproof barrier
- function in immunity
- control water loss
b) Melanocytes
- located at the base of the epidermis
- Produces Melanin – responsible for skin color and absorption of UV light
- the darker you are, the more protection against cancer
- acts as an umbrella covering that shields DNA from UV
c) Merkel’s cell
- It is located at the basal layer of the epidermis but can usually be located only with the use of an electron microscope
- one of the receptors
- scarcely located in the palms, soles, oral and genital epithelium d) Langerhan’s cell
- play a role in cell-mediated immune responses in coordination with T cell
- originates in the bone marrow and migrates into the epidermis

Layers of the Epidermis
a) Stratum Germinativum/Basale
- innermost
- cells are columnar in shape
- where melanin is found in greatest amount
- lies close to the dermis layer
- cells at the basale layer receives nutrition from the dermis via diffusion and undergo mitosis every 19 days and older cells are pushed upward undergoing changes in shape and chemical composition through a process known as keratinization

b) Stratum Spinosum
- cells are irregularly-shaped known as prickle cells (have sharp cytoplasmic projection at the covering)
c) Stratum Granulosum
- cells are nucleated granular cells which contain keratohyalin granules (contain lipids with desmosomal connections which helps to form waterproof barrier) ←keratin – prevents water loss from the body

*not responsible for water loss in the pores
d) Stratum Lucidum
- thin transparent layer
Skin moisture-can only be seen in thick skin like the palms and soles immunity e) Stratum Corneum
- composed of dead keratinized cells (contain keratin -acidic in nature)
- serves as a durable overcoat of the body
- DESQUAMATION – natural process of breaking apart of dead...
tracking img