week 4 Flashcards
whats the 4 primary tissue types
epithelium
connective tissue
nervous tissue
muscle
whats nervous tissue
intervnetal communication (brain, spinal cord and nerves)
whats muscle tissue
contracts to cause movement
muscles attached to bones (skeletal)
muscles of heart (cardiac)
muscles of walls of organs (smooth) INVOLUNTARY
whats epithelial tissue
form boundaries between different environments.
protects, secretes, absorbes, filters
skin surface
whats connective tissue
supports, protects, binds tissue together
bones, tendons,
where are the four primary tissues in the skin
- Stratified squamous epithelial tissue in the epidermis
- Connective tissue in the dermis
- Smooth muscle tissue in arterioles and attached to hairs (arrector pili)
- Nervous tissue in nerves
whats skin also called
integument
what s the three lakers of skin
1. Epidermis • outer epithelial layer 2. Dermis • a deep supporting layer of dense connective tissue 3. Hypodermis • subcutaneous layer composed of loose connective & adipose tissue - connective tisse, insulate and protect tissue underneath
whats stratified mean
lots of layers
whats squamous mean
flattened
whats the epidermis
- outer layer
- avascular
- oxygen and nutrients diffuse from the blood vessels of the dermis
- constants renewal replaced every 25-45 days
the process of creating new epiderms
cells move from the deepest layer of epidermis to more superficial layer, they flatten, produce large amounts of keratin (tough, waterproof protein) and eventually die
whats the most superficial and deepest later of the 5 epidermal layer
stratum corner: dead keratinised flattened cells
stratum basale:alive, needs access to oxygen and nutrients otherwise they will die
what are keratinocytes
produce keratin
what are melanocytes
produce melanin
whats the dermis
consists of connective tissue cells include macrophages and fibroblasts which produce collagen and elastic fibbers to provide strength and flexibilty contains: - blood vessles - lymphatic vessels - nerves and sensory receptors - sweat glands - hair follicles
whats thick skin
covers palms, fingertips and soles off feet
- very thick epidermis
- lacks hair and oil glands
whats thin skin
covers rest of body
- has hairs, sweat and oil glands
- allows suppleness and agilty
does thick of thin skin heal quicker after an injruy
Injury where there are lots of hair, sweat glands, oil glands will heal quicker. Eg scull
THIN SKIN
6 major functions of the skin
- Protection a.Chemical
b. Physical
c. Biological - Sensation
- Metabolic function
- Blood reservoir
- Excretion
- Temperature regulation
how does the skin profile protection
chemical barrier:
- acidic outside of skin
- dens inis (natural antibiotic) secreted by skin cells to kills bateria
- melanin protects DNA in underlying cells from UV damage
Physical barrier:
- keratin and oily secretions block most water from entering/ leaving body
Biological barrier:
- macrophages engulf and dispose of viruses and bacteriaa that manage to penetrate the epidermis
how does the skin provide sensation
pain receptors: nocieptors
temperature receptors: chemoreceptors
touch, pressure and vibration receptor: mechanorecpetos
how does skin have metabolic function
synthesis of vitamin D precursor
how does skin have blood reserviour
can hold up to 5% of body bloods volume
how does skin ecretion
• Nitrogenous wastes and salt are excreted in sweat
how does skin regulate temperature
increase in temperature leads to: - dilation of vessles - increase sweat gland activie decrease in temperature leads to: - contrictin of precapiliary sphincters to minimise heat loss to external environment TEMPERATURE MONITORED BY thermorecpetors
what does minor wounds invole
just epidermis
what does major wounds involve
both epidermis and dermis
skin repair two processes
regeneration
fibrosis
whats skin repair regeneration
- replaces destroyed tissue with the same kind of tissue can be restored to normal if:
- damage is minor and involves just the epidermis
- epidermis has stem cells to regenerate lost tissue
what skin repair fibrosis
• replaces destroyed tissue with scar tissue
• damage that includes the dermis leads to repair by
fibroblasts
• scar tissue does not have any of the same qualities as the tissue before the injury
whats the three stages of skin repair
Stage 1. Inflammation: formation of blood clot
Stage 2. organisation or proliferative stage: formation of
granulation tissue
Stage 3. maturation: regeneration and fibrosis
stage 1 of skin repair
inflamation
Function: prepare the wound for repair, eliminate invading organisms and remove foreign tissue.
damaged blood vessels release inflammatory chemical (mechrophasges)
clotting proteins produce a blood clot to stop from blood loss
stage 2 skin repair
orginsation or proliferation stage
Function: to synthesise ECM including collagen and restore a blood supply
- blood clot replaced by granulation tissue )bring oxygen and nutrients required for healing)
- fibrolasrts produce collagen fibres that bridge the gap
- epithelial stem cells multiply and migrate over the granulation tissue
stage 3 skin repair
maturation
- collagen laid down contracts to pull wound edges together
- existing blood vessels are compressed so the scar is avascular
MINOR WOUND: epithelial stem cells newr wound site divide and growunder scuba and regenerate epithelium, scab falls off and skin reflects preinjury tissue (will have underlying scar tissue)
MAJOR WOUND: scar tissue visible repair prodominately by fibrosis (has no elasticity or flexibility, no hair or sweat glands)
skin damage due to Bruns
- may lead to tissue damage, denture proteins, cell death
- looks of skin function
- immediate threat due to dehydration and electrolyte
- infection via bacteria
burn classification
- 1st degree - Superficial burn
- 2nd degree - Partial- thickness burn • Superficial partial-thickness burn • Deep partial-thickness burn
- 3rd degree - Full-thickness burn • 4th degree - Subdermal burn
1st degree: superficial burns
- confined to the epidermis
- no barrier functions altered
- maybe painful
- general heals by itself in less than a week without scarring
- sunburn
2nd degree burn: superficial partial thickness burn
- destruction of entire epidermis and no more than a third of dermis
- vessels injured
- epidermis lifts off and causes blisters
- most painful burns because nerve ending in skin are exposed
- remming blood low is adequate and infection risk low
- heal within 1-3 weeks
2nd degree deep parital thickness burns
- destruction of epidermis and most of dermis
- dead tissue (NO BLISTERS)
- wound appears white and dry
- blood flow compromise
- vulnerable to infection
- reduced pain because nerve endings have been destroyed
- would heal over 3 weeks
3rd degree full thickness burn
- complete destruction of epidermeris and dermis
- results significant scarring
- generally require a skin graft
- no painful initaitlla
- appearance can be any colour
4th degreee: subnormal burns
- compete destruction of epidermis and dermis
- would appears charred,, dry and brown or white without sensation
teatime often requires ampuation
whats primary concern for burns and then secondary
fluid loss
then infection
why do full thickness burns require skin graft
would take too long to heal by itself (open up to infections) therefore skin grafts used
whats hypertrophic burns scares
scar with excessive collagen synthesis, leading to a raised or thickened area but contained within the wound margin
- are more prominent around joints where skin tension and movement are high (would impact on ROM)
burn scar contractors
pathological result of long term shrinkage of a scar
• results in the inability to perform full range of motion of a joint
treatments include:
• Stretching
• Splinting
• Massage
• Skin grafting • Silicon gels
