Integumentary system Flashcards
What are the two layers of the skin?
Epidermis and dermis
State 4 types of cell in the epidermis layer of skin
- keratinocytes
- melanocytes
- Merkel cells
- dendritic cells
What are keratinocytes?
- cells in epidermis layer of skin
- Main cell type
- ‘Born’ deep in epidermis (of stratified epithelial cell layer) - against basement membrane and migrate to surface of skin – change biology and filled with protein keratin
- Produce keratin (creating protective layer) – which flatten as die and become waterproof
What are melanocytes?
- type of cell in epidermis layer of skin
- Deepest layer of epidermis
- Secrete melanin (pigment which is explored from here to keratinocytes to protect them from UV rays)
What are merkel cells?
- cell type in epidermis of skin
- Specialised sensory cells
- Light touch / textures
- Can release local hormone to change sensitivity of nerve endings locally
What are dendritic cells?
- type of cell in epidermis layer of skin
- Ingest invaders and foreign materials
- Activate immune defences of body
- Present the antigen of pathogen for immune response
State the 4 layers of the epidermal
- stratum corneum
- stratum glanulise
- stratum spinosum
- stratum basale
What are the features of the stratum corneum layer of epidermal?
- first layer
- Make off fully differentiated keratinocytes - flatten
- Lamella granules and keratin contained
- Killed by apoptosis (programmed cell death)
- Mechanically resistant – layers can detach to protect the layers of cells underneath
What are some chracteristics of the strata granulise layer of the epidermal?
- 2nd layer
- 4-6 layers thick
- Keratinocytes start to flatten out – accumulating lamella crystals or granules made of glycolipids which are waterproof – to form stratum corneum cells
What are the characteristics of stratum spinosum layer of the epidermis?
- third layer
- Spiky layer – keratinocytes
- Spiky is deaminates – join cell to cell into strong tough network – anchoring cytoskeletons of cells improving integrity of top layer
- Dendritic cells patrol waiting to be activated –like activated macrophages) – for pathogens
What are the characteristics of the stratum basale layer of the epidermis?
- final and fourth layer
- Sits on basement membrane sitting on dermis
- Basal layer
- Found Stem cells dividing, dividing keratinocytes and daughter cells push up through layers to surface
- divide by mitosis
- melanocytes here to produce melanin
- Merkel cell – sensory cell – accosted with single nerve fibre which ate tactile
What is sloughing?
Shredding dead surface cells from skin – normal part of skin regeneration – 50,000 cells lost per minute
- Outer layer (epidermis) replaced every 21-45 days
What are the two layer of the dermis?
- papillary
- reticular
What other cells are embedded in the dermis layer of skin?
- collagen
- elastin
- blood vessels
- nerve endings
- sweat glands
- hair follicles
What chracterises the paillary layer of the dermis?
- loose areolar connective tissue
- flexible, stretchy and elastic layer
- elastin, collagen, blood vessels in loops to form dermal papilla which increases surface area
- provide nutrients for epidermis (no vessels need to diffuse into epidermis)
- dermal papilla
What characterises the reticular layer of the dermis?
- dense irregular connective tissue so lots of collagen and elastin return to position
- bundles of collagen heavier and thicker creating strong layer for skin (leathery)
What is dermal papilla?
- associated with touch receptor called Maecenas
- fine touch sense
- useful in magnifying vibrations and sensations and physical attributes of environment Maecenas corpunecule and touch receptors
- rich in small capillaries
What are the functions of skin?
- protection
- temperature regulation
- secretion
- cutaneous sensation
How does the skin provide protection?
- Physical protective barrier – dendritic cells in epidermis patrolling for immune response
- Chemical water resistance against dehydration
- UV protector in epidermis – melanocytes
- Trama – top dead cells of epidermis
What is trama?
top layer of dead cells of epidermis
How does skin regulate temperature when its too hot?
- Vasodilation
- **Evaporate sweat from skin **
How does vasodilation effect temperature?
- dermal perplexes of blood vessels and small capillaries into dermal papillary areas
- controlled in hypothalamus
- sympathetic nervous system reduced
- floods the skin with warm blood so evaporative cooling the heat is lost
How does sweat evaportation effect temperature regulation?
- evaporative cooling
- eccrine sweat glands - produce salty watery sweat
- also produce and release antibodies – germicidin – innate immune response – destroys cell membrane of bacteria – control microbiome on the skin
What process help temperature regulation when its too cold?
- vasoconstriction
- arrector pili muscles
How does vasoconstriction effect temperature regulation when its too cold?
- when cold
- parasympathetic nervous system reduced
- capillaries diameter reduced
- blood rediverted mad less evaporation
- preserving body temperature
How do arrector pili muscle effect temperature regulation?
- sympathetic nervous control
- associated with hair follicle
- activated pull on hair follicle making stand up hairs on surface
- creating a protective barrier layer of warm air trapped
What are three glans in skin?
- sebaceous gland
- apocrine gland
- eccrine gland
What does the sebaceous gland do in skin?
- oil associated with hair follicles secreting milky oil called sebum
- protective
- waterproof surface of the skin also creates the acid mantle (pH 4.5-6.2)
- select and control microbiome
- secrete antibacterial lipids (swing lipids)
- control sweat and microbiome on surface of skin
What do apocrine glands do in skin?
- anogenital and axillary areas (start in puberty)
- secrete health milky sweat around the genitals and anal area and under arms
- secondary sexual characteristic
- sexual scents and signalling
What do eccrine glands do in skin?
- producing dermicide and antibacterial peptide and watery salty sweat
What are four structures effecting cutaneous sensation in the skin?
- free nerve ending
- inflammatory mediators
- pacinian corpuscle
- hair plexus
How do free nerve endings produce cutaneous sensation in the skin?
- response to pressure and temperature changes
- encode noiceptic signals (pain signals) – noseception
How do inflammatory mediators effect cutaneous sensation?
- skin is broken
- released in broken blood vessels
- nocepetive signals to central nervous system
- pain, temperature and touch and pressure
How do pacinian corpuscle repsond to sensation?
- register vibrations texture and pressure
How do hair plexus effect cutaneous sensations?
- array of sensory nerves attached to hair follicles
- sensing the movements of hair on skin
- Minus corpuscles and merkle cells – deep epidermis
What is sensory homunculus?
- Sensory nerve endings are not evenly disrributed around area of the body
- lots in hands where on legs the endings are more widely spread
- reflected in organisation of the brain
What are some forms of non-verbal communication in the skin?
- Blushing, pheromones (sexual maturity) and body odour/stress odours
Explain why there are areas of the skin with thick and non-hairy sections
- Statum lucidium – clear layer (extra layer in the layers of skin)
- Palms and sole of the feet
- made of flat, dead keratinocytes laying superficially to the stratum granulosum
- not fully understood - possibly easily detached in rubbing
- only equine glands but no oily protective
- many Pacinian corpuscles sensing vibration, touch
- not particularly functional vasodilation
What are three chracteristics effecting skin colour?
- Derivative of haemoglobin – colour of skin especially when red
- Melanin – brownish pigment created in epithelial layer of - glanasal sites
- Carotene – vitamin A escreted in sweat (more in sebateus) – can lead to discolouration eg. Eating too many carrots
How does derivative of haemoglobin effect skin colour?
going red and blushing
How does melanin effect skin colour?
brownish pigment created in epithelial layer of - glanasal sites
How does carotene effect skin colour?
- vitamin A escreted in sweat (more in sebateus)
- can lead to discolouration eg. Eating too many carrots
State some abnormal reasons for colouration
- Cyanosis – rainout syndrome – digets of the hands looks blue due to deoxygenation
- Jaundice – excess of bilirubin accosiated with liver disease or bile duct problems – causing yellow looking
- Pallor – dependant of blood flow in dermis – vasodilation
- Albinism – reduced or absence of melanin – usually genetic variation
- Haematoma – damage to the skin – red blood cells accumulate in damaged bruised areas and neutrophils eventually remove them
Breifly state why the skin scares?
- Epidermal regeneration usual very efficient
- Dermal regeneration less well organised
Whats the process of scaring of the skin?
- Fibroblasts (tissue prdocuing cells) lay down framework of fibres – replacement of damaged tissue
- Irregular arrangement of fibres – not same as original layout
- Hair follicles / sweat glands etc. don’t regenerate – smoot looking and different caracteristics
- Irregular fibre framework – different pattern of blood vessels – stretch mark as dermis is stretched and tore/stressed – repaired not matching orginal fibres
What are keloids?
- due to excessive scar tissue and overactive fibroblasts
- as less control from control chemicals in skin
- genetical varieation as overactive fibroblasts
