Integumentary tissue pt 1 Flashcards
6 functions of integumentary system
- Protection
- Body temperature Regulation
- Cutaneous sensations
- Metabolic functions
- Blood reservoir
- Excretion
Protection in IS
3 types of barriers
- Chemical: low pH secretions (acid mantle) and defensins retard bacterial activity
- physical/mechanical barrier: keratin + glycolipids block most water and water soluble substances
- limited penetration of skin by lipid-soluble substances, plant resins, organic solvents, salts of heavy metals, some drugs - Biological barriers: dendritic cells, macrophages
Body temperature regulation in IS
500 ml/day of routine perspiration, elevated temeperature, dilation of dermal vessels and increased sweat gland activity to cool the body
Cutaneous sensations in IS
temperature, touch (merkel, meissner cells) and pain (free nerve endings)
Metabolic functions in IS
Synthesis of vitamin D precursor and collagenase (increases collagen + reduces wrinkles)
Blood reservoir in IS
Up to 5% of body’s blood volume
Excretion in IS
nitrogenous wastes and salt in sweat
3 major regions of the skin
- Epidermis: superficial region
- Dermis: middle region
- Hypodermis: deepest region
- subcutaneous layer deep to skin - mostly adipose tissue
Epidermis and its 4 cells
- Keratinized (keratin proteins that keep them together) squamous epithelium
- Avascular
Cells:
- Keratinocytes: produces fibrous protein keratin (connecting all squamous cells together to create a hard barrier)
- Melanocytes: 10-25% of cells in lower epidermis, produces pigment melanin (protects cell nuclei from sun damage)
- Epidermal dendritic (langerhans) cells: macrophages that help activate immune system
- Tactile (Merkel) cells: touch receptors
5 layers of epidermis
Stratum basale, Stratum spinosum, Stratum granulosum, stratum lucidum, stratum corneum, (Come Lets Get Sun Burnt)
Stratum basale
EPIDERMIS
- Basal layer
- Deepest epidermal layer firmly attached to dermis
- single row of stem cells; source of new skin cells
- stratum germinativum: cells undergo rapid division
- journey from basal layer to surface takes 24-45 days
Stratum spinosum
EPIDERMIS
- Prickly layer
- Cells covered with thorn like spines: provides strength and flexibility
- Abundant melanin granules and dendritic cells (pigment + defensive cells)
Stratum granulosum
EPIDERMIS
- Granular layer
- Thin, grainy layer
- 3-5 layers of flattened keratinocyte
- intermediate filaments located here
- lamellated granules: secretion which acts as water repellant sealant (waterproofing)
Stratum lucidum
EPIDERMIS
- Clear layer
- In thick layer - palms and soles of feet
- almost no organelles
- few rows of flat, dead keratinocytes
Stratum corneum
EPIDERMIS
20-30 rows of dead, flat, keratinized, membranous sacs
- 3 quarters of epidermal thickness
- cells are shed continuously
- Functions: protects from abrasion + penetration, waterproofs, barrier against biological/chemical/physical assaults
Dermis and its 2 layers
Strong, flexible CT and include fibroblasts, macrophages, and occasionally mast and white blood cells
2 layers: Papillary (loose areolar CT) and reticular (dense irregular CT)
Papillary layer
DERMIS
- Areolar CT w/ collagen + elastic fibers + blood vessels
- Dermal papillary: form friction ridges (gives us our fingerprints)
- Dermal papillae contain: Capillary loops (blood supply), meissner’s corpuscles (tactile -> touch/vibration receptors) and free nerve endings (pain receptors - touching something hot)
Reticular layer
DERMIS
- 80% of thickness of dermis
- collagen fibers for strength + resiliency
- elastic fibers for stretch-recoil
- blood vessels, nerves, hair follicles, sebaceous + sudoriferous (sweat)
- Deep sensory receptors (pacinian corpuscle - deep pressure)
Psoriasis
Skin issue disorder
- Due to genetics, body produces abnormal keratin and build up in places
- Speeds up cell growth of abnormal keratin and scales up through body
- painful due to no covering, scaling, limited movement
Neuropathy
small steps, poor balance, poor stepping response
- due to lack of sensation
- sensation disease
Skin marking of cleavage lines
- Collagen fibers arranged in bundles form cleavage (tension) lines
- incisions made parallel to cleavage line heal more readily
3 pigments of skin color
- Melanin (yellow-reddish brown to black)
- responsible for dark skin colors
- produced in melanocytes, migrated to keratinocytes where it forms pigment shields for nuclei
- freckles and pigmented moles (local accumulations of melanin) - Carotene (yellow to orange)
- obvious in palms and soles - Hemoglobin (pinkish hue of skin)
What happens with exposure to sunlight
- damages skin
- elastic fibers clump = leathery skin
- alters DNA of skin cells and lead to skin cancer
Skin color abnormalities
- Jaundice - liver disorder (yellowish - sclera/white part of eyes )
- Erythema - fever (reddish)
- Cyanosis - poor oxygenation as capillaries keep warm blood peripherally (bluish)
Albinism + vitiligo
Pigment disorders
Albinism: melanin is not producing so there is no protective layer of the skin against the sun and now sensitive to sunlight (burns), issues with retinas (vision loss)
Vitiligo: unorganized discolored patches of the body due to disorder of melanin throughout the body
Friction ridges
- Increase friction for better grip
- houses sweat gland ducts
- epidermal ridges lie atop deeper dermal papillary ridges to form friction ridges of fingerprints.
