physiology Flashcards
what are keratinocytes?
- produces keratin
- that protects the skin from abrasion/damage/heat
what are melanocytes?
- produce melanin
- protects from UV rays
what are Langerhern cells?
- produced in red bone marrow
- facilitate an immune response
what are Merkel cells?
transmits sensory information to nerves in deeper layers
what are phagocytes?
- neutrophils & macrophages
- emigrate to affected areas
- ingest foreign or dead tissues
what is the effect of age on the skin?
- prolonged inflammatory phase of healing
- due to more protein degradation
- prolonged overall healing
what are the 6 functions of the skin?
1 - thermoregulation
2 - blood reservation
3 - protection
4 - cutaneous sensations
5 - excretion and absorption
6 - synthesis of vitamin D
what are the 5 cardinal signs of inflammation? PRISH
P - pain (chem release)
R - redness (inc BF)
I - immobility
S - swelling (fluid accum from plasma)
H - heat (higher BF)
what happens in the inflammatory phase of wound healing?
- platelets cause haematoma
- bradykinin and histamine cause vasodilation and increased vessel permeability
- phagocytes remove foreign or dead tissue
- mesenchymal cells arrive
what happens in the migratory phase of wound healing?
- scab forms
- epithelial cells grow underneath from stratum basale
- fibroblasts migrate to the wound and form scar tissue (glycoproteins and collagen)
- blood vessels begin to regrow
what happens in the proliferative phase of wound healing?
- epithelial tissue continues to grow
- fibroblasts deposit collagen fibres in random patterns
- wound begins to contract
- 2-3 weeks
what happens in the maturation phase of wound healing?
- remodelling of collagen fibres
- decreased fibroblasts
- blood vessels healed fully
- scab sloughs off once the epidermis is thick enough
what are the 3 skin layers? EDS
epidermis
dermis
subcutaneous layer
what is the epidermis?
- 5 layers (stratum)
1 - stratum basale- deepest new skin cells made from stem cells
- moves through the layers
2 - stratum spinosum - cells joined tightly together
- strength and flexibility
3 - stratum granulosum - the border between live and dead cells
- waterproof
4 - stratum lucidum - layers of dead cells that act as protection
5 - stratum corneum - 25-30 layers of flattened dead keratinocytes
what is the dermis?
- made of elastin
- contains blood vessels
- subcutaneous glands = secret sebum to keep skin supple
- sweat glands = regulate temp and excrete waste
what is the subcutaneous layer?
- lipid cells provide protection
- contains blood vessels and nerves
what are the 3 phases of muscle strain healing?
inflammation
regeneration
remodelling
what happens in the inflammation phase of muscle healing?
- necrosis of myofibrils
- vasodilation
- increased BV permeability
- phagocytosis
- haematoma formation
what happens in the regeneration phase of muscle healing?
- stem cells migrate to the area and differentiate into myoblasts
- myoblasts develop into myotubes
leading to myofibril regen - fibroblasts produce collagen to stabilise wound and provide scaffolding for new muscle fibres
what happens in the remodelling phase of muscle healing?
- maturation of regenerated myofibrils
- gradual recovery of muscle function
- reorganisation of scar tissue
what are the different types of muscle contraction?
either isotonic or isometric
isometric = no change in muscle length
isotonic = change in muscle length
isotonic can either be concentric or eccentric
concentric = muscle shortens
eccentric = muscle lengthens
what is the epimysium?
- outer layer
- dense
- irregular
what is a fasicle and what surrounds it ?
- bundle of muscle fibres
- surrounded by perimysium
what are muscle fibres and what surrounds them ?
- muscle fibres are made up of myofibrils
- and are surrounded by endomysium
what do myofibrils contain?
- contractile sarcomeres
- sarcomeres are overlapping protein fibres called actin and myosin
what does the golgi tendon do?
monitors the force of muscle contraction
what is a muscle spindle?
monitors changes in muscle length
what is the periosteum?
- outer layer
- protects and nourishes as it has a good blood supply
what is the medullary cavity ?
- space inside bone
- lined by endosteum
- spaced and filled with yellow bone marrow
- hollowness means bones are light
what is hyaline cartilage?
- shock absorbtion
- reduces friction between bones
compact bone
- densly packed osteocytes
- protects and supports
spongey bone
- made of lamellae arranged into trabeculae beams
- cavities are filled of red bone marrow
- RBM makes RBC
- cavities make bone lighter
what is the epiphyseal plate?
growth plates in children
epiphyseal line in adults
what is the diaphysis of a bone?
the main body of the bone
what are the epiphyses of a bone?
the ends of the bone
what are the 4 types of bone fractures
Open = bone out
Comminuted = crumbled
Greenstick = one side broken other bent only in children
stress = microscopic fissures
