The integumentary system Flashcards
Name some organisms found in skin microbiome
-bacteria, yeast, fungi, multicellular organisms, viral particle
What are the main layers of the skin?
-epidermis
-dermis
-hypodermis
what are the four main cell types found in the epidermis?
-keratinocytes
-melanocytes
-merkel cells
-dendritic cells
Function of keratinocytes
-produce keratin
-main cell types
-deep in epidermis
Function of melanocytes
-deepest layer of epidermis
-secrete melanin
(melanin is a protective pigment that acts as a sunscreen for keratinocytes)
Function of merkel cells
-specialised sensory cells
-light touch
Function of dendritic cells
-ingest invaders and foreign materials
-activate immune defences of body
Name the epidermal layers
-startum corneum
-stratum granulosum
-stratum spinosum
-stratum basale
Fuction of stratum basale
-stem cells that reproduce
-produce melanin and decorate keratinocytes with the pigment
-merkel cells are also here
function of the stratum spinosum
keratinocytes join together as a sheet by producing proteins on the surface
-keratinocytes have begun to differentiate
Structure and function of stratum granulosum
-thin
-start to specialse
-flattern out and accumulate keratin and lammellae granuels (glycolipids)
-helps keratinocyts become waterproof
structure and function of stratum corneum
-keratinocytes become full with keratin and lammelae granueles
-cells within this layer are cornified so they die
-they are water, mechanically, chemically resistant
order the epidermal layers from bottom to top.
-stratum basale
-stratum spinosum
-stratum granulosum
-stratum corneum
Why do cells slough off?
-protective feature of the skin to get rid of multicellular organisms
-normal part of skin regeneration
Name features found in the dermis
-collagen
-elastic fibres
-blood vessels
-nerve endings
-sweat glands
-hair follicles
Name the layers of the dermis
-dermal papilla
-papillary layer
-rectiular layer
what is the recticular layer of the dermis?
strong thick bundles of collagen
what is the function of dermal papilla in the dermis?
enhance sense of fine touch
increases the surface area
structure of the papillary layer of the dermis
modified areolar connective tissue
Name some functions of the skin
-protection from infection
-protection from dehydration and chemicals
-protection from physical damage
-temperature regulation
-sectretion
-cutaneous secretion
List some features involved in temperature regulation in the skin.
-subpapillary plexus
-sweat pore
-eccrine sweat gland
-arrector pilli muscle
-hair root
-cutaneous plexus (blood supply)
-adipose tissue
what does the arrector pili muscle do?
consists of a small band of smooth muscle that connects the hair follicle to the connective tissue of the basement membrane.
What are the three parts of the skin involved in secretion?
-apocrine gland
-anogenital
-axillary
function of free nerve endings im cutaneous sensation
respond to damage of the skin.
sense temperature and a vague sense of touch
Function of hair plexus in cutaneous sensation
-sensory
-tells us what is happening to hairs on the surface of skin
Function of pacinian corpuscle in cutaneous sensation
respond to vibration, pressure sensing in the skin
What does the sensory homunculus image show us?
the distribution of nerve endings in the body
list some non verbal communication of the skin
-blushing
-pheromones
-body odor
-stress odor
Where is the stratum lucidum found?
between the stratum granulosum and stratum corneum
What is the structure of the stratum lucidum?
-clear liquid
-thin, translucent band
-2-3 layers
-flat and dead keratinocytes
What is skin colour affected by?
-haemoglobin
-melanin
-carotene
Why is melanin produced?
To protect keratinocytes
Name some abnormal colourations of the skin
-cyanosis- poor circulation
-jaundice
-pallor
-albinism
-haematoma
How does scaring of the skin form?
1-fibroblasts lay down framework of fibres to replace damaged tissue
2-irregular arrangement of fibres
3-hair follicles/ sweat glands dont regenerate
4-irregular fibre framework-different blood vessel patterns
define haemostasis
-a protective response to the rupture of blood vessels.
What does haemostasis prevent?
-excess blood loss and is a precursor for tissue repair
-limits excessive bleeding following an injury
-localised protective respose
What are the three stages of haemostasis?
1-vascular spasm
2-formation of the platlet plug
3-coagulation
what is the function of the eccrine gland?
temp control
antibacterial properties
contract when we are cold forcing hair up
What is the function of aprocrine glands?
sexual scent gland
What is the function of the sebaceous gland?
-antibacterial propeties
-help prevent water loss
-lubricate skin and hair
What is the name of the process in which eccrine glands secrete?
merocrine/exocytosis
Name the secretion process by aprocrine sweat glands
merocrine/exocytosis
Name the proccess in which sebaceous glands secrete?
holocrine
What does the ecrrine gland secrete?
hypotonic filtrate of blood plasma
What does the apocrine gland secrete?
filtrate of blood plasma with added proteins and fatty substances
What does the sebaceous gland secrete?
sebum
What happens during the first stage of haemostasis- vascular spasm?
narrowing of the arteries caused by a persistant contraction of blood vessels- vasoconstriction.
-Reduces blood flow through the artery sending less oxygen to nearby tissues
What happens in the second phase of haemostasis-platelet plug formation?
-platelet adhesion
-platelet activation
-platelt aggregation
Endothelial cells release nitric oxide and a prostocyclin preventing platelet aggregation.
as more platelets aggregate they release more chemicals aggregating more platlets ect…
What happens in the final stage of haemostasis-coagulation?
lead to the formation of prothrombin activator.
intrisic responds to internal damage of the vascular endothelium
extrinsic-is activated secondary to extensive trauma
reinforces the platelet plug with fibrin threads acting as a molecular glue.
what are the stages of soft tissue repair?
-haematoma
-scab formation
-granulation phase
-regenerating and remodelling phase
What happens during the haematoma and scab formation in soft tissue repair?
-Trauma causes injured cells (mast,tissue) to realese inflammatory chemicals
-inflam chemicals make local blood vessels leaky allowing white blood cells,fluid,clottimg proteins to seep into injured area
clotting seals injury preventing bacteria entering
-scab forms
day 0
day 0-3
What happens during the granulation phase of soft tissue repair?
-clot replaced by ingrowth of fragile cappilaries restoring vascular supply
-fibroblasts multiply and produce growth factors and collagen fibres that bridge the gap, when completed fibroblasts undergo apoptosis-die
-macrophages phagocytize dead and dying cells
-surface epithelial cells multiply and begin to migrate over granulation tissue
day 4-14
What happens during the remoddeling and regenerating of soft tissue repair?
-fibrosed area matures and contracts pulling together margins of the wound.
-as it regenerates the epithelium thickens under the scab-detached
-a fully regenerated epithelium with underlying area of scar may be visible.
day 14- 2 years
what are the four stages of bone healing?
-haematoma
-soft callous
-hard callous
-remodelling
What happens during the haematoma phase of bone repair?
-blood vessels in the periosteum are torn when a bone breaks
-forms hemorage blood clots form a haemotoma, bones are deprived of nutrition and die.
-tissues become swollen, painful or inflamed.
0-2 days
What happens during soft callous formation of bones?
-new blood vessels grow into the clot. Fibroblasts and chondroblasts invade the fracture site.
fibroblasts produce collogen fibres that connect bone ends.
chondroblasts secrete a catilaginous matrix that bulges and calcifies forming a fibrocartilaginous callus.
-repairs the soft tissue.
2-4 days
What happens during hard callous repair during bone healing?
-osteoblasts begin forming spongy bone.
-osteoblasts begin to lay down trabeculae of new bone around and within the fibrocartilaginous callus.
-trabeculae span the width of the callus uniting the two fragments of broken bone.
-gradually the fibrocartilaginous callus is replaced by immature bone converting it to bony callus.
-process repeats the events of endochondral ossification
6 weeks
What happens during the remodelling of the bone?
-after the bony callus is remodelled
-the excess material on the diaphysis exterior and within the medullary cavity is removed.
compact bone is laid down to reconstruct the shaft walls.
-repsonds to the same set of mechanical stressors.
takes years
