Soft Tissue Structure, Function & Healing Flashcards
Four types of tissue
Connective
Epithelial
Muscle
Nervous
Epithelial tissue…
Includes epithelia and glands
Cover internal or external surfaces
Cells bound closely together
Has an exposed surface
Are avascular
Cells continuously regenerating
Epithelial tissue functions
Physical protection: from abrasion, dehydration and destruction
Control permeability: substances leaving or entering body cross epithelium, Variable permeability , absorption, secretion, excretion, diffusion
Provide sensation: sensory nerve supply, smell, taste, hearing, sight
Provide info on internal/ external environment
Produce specialised secretions: produced by glands
Structure of epithelial cells
Coated in microvilli and cilia, lateral surfaces, Golgi apparatus, nucleus, mitochondria, basal surface
Endocrine glands
Secrete hormones into cellular spaces then blood
Hormones regulate or co ordinate activities of various tissues, organs and systems
Examples: pituitary, thyroid, thymus
Exocrine glands
Secrete products into ducts that empty onto the epithelial surface
Examples: digestive enzymes, sweat, tears
Connective tissue
Throughout the body
Never exposed
Connects epithelial tissue to rest of body
Highly vascular
Fill internal spaces
Functions of connective tissue
Structural framework for the body
Transports fluids and dissolved materials
Protects delicate organs
Connects other types of tissue
Stores energy (triglycerides)
Defend body from microorganisms
Cartilage is
Closely packed collagen fibres embedded in a firm matrix gel containing chondrocytes & proteoglycans
Types of cartalidge
Hyaline cartilage
Elastic cartilage
Fibrocartalige
Hyaline cartalige
Most common
Tough but flexible
Found:
Most joints covering articulated surfaces
Between ribs and sternum
Nasal cartalige
Respiratory tract
Elastic cartalidge
Numerous elastic fibres
Resilient but flexible
Found:
External flap (auricle)
Epiglottis
Auditory tube
Small cartilages in larynx
Fibrocartilage
Densely interwoven collagen fibres
Little ground substance
Durable & tough
Resists compression & absorbs shock
Found:
Between vertebrae
Between pubic bones
Meniscus
where do membranes occur?
when epithelial tissue is combined with connective tissue
four types of tissue membrane
mucous membrane
serous membrane
cutaneous membrane
synovial membrane
mucous membranes
line passageways that lead to exterior i.e digestive, respiratory, urinary & reproductive tracts
epithelial surfaces kept moist to reduce friction and allow secretion/ absorption
thin layer of epithelial cells
serous membranes
- line sealed, internal subdivisions of body cavities
- not open to exterior
- very thin and transparent
- firmly attached to body walls & organs that they cover
- minimise friction: serous fluid produced
examples of serous membranes
peritoneum: lines peritoneal cavity (abdomen) covers surface of exposed organs peritonitis
pleura: lines pleural cavity, covers the lungs pleurisy
pericardium: lines pericardial cavity,
covers heart pericarditis
synovial membranes
around joint cavity of synovial joints, forms synovial capsule
made up of connective tissue with macrophages and fibroblasts
synovial fluid within capsule- lubricates and nourishes hyaline cartilage
movement of joint stimulates formation and circulation of synovial fluid
cutaneous membranes (skin)
Two layers
- epidermis (epithelial tissue)
- dermis (connective tissue)
Subcutaneous layer of loose connective tissue
Accessory structures
functions of cutaneous membrane?
• protection of underlying tissue
• excretion of salts, water & waste products
• maintenance of temperature
• production of melanin & keratin
• synthesis of vitamin D
• storage of lipids
• sensation
• co-ordination of immune response to pathogens/ cancers in the skin
micro-tears
localised pain
tenderness
no visible bruising
minimal loss of function
no laxity
partial tear
moderate swelling
bruising
poorly localised pain
impairment and painful ROM
may have some instability
complete tear / rupture
audible pop/ acute pain
considerable swelling or bleeding to joint (Haemarthrosis)
significant laxity/ instability
symptoms may later settle
muscle & tendon injuries sprain
typically caused by over contracting or lengthening a muscle causing tearing of collagen
most commonly occurs in the eccentric phase of contraction
called a strain
factors that cause tissue damage?
injury: physical / thermal / radiational / electrical / chemical
infection: viruses / bacteria / fungi / protozoa
infarction: myocardial infarct
immune reactions: foreign protein hypersensitivity / autoimmune
types of body tissue (parenchymal tissue)
- functioning cells of organs
- e.g neuronal (brain) tissue, epithelial (skin) tissue, cardiac myocyte (heart) tissue, hepatocyte (liver) tissue
types of body tissue (Stromal (interstitial) tissue)
supporting connective tissues
contains many cell types including fibroblasts
blood vessels
nerves & nerve endings
3 Types of tissue healing
-
Resolution
rapid healing of mild injury
epithelial cells slough & regenerate -
Tissue Regeneration
specialised tissue is replaced by the proliferation of surrounding undamaged specialised cells
i.e injured tissues are repaired with parenchyma -
connective tissue repair (replacement)
lost tissue is replaced by granulation tissue which matures to form scar tissue
Resolution healing
occurs in acute inflammatory response to minor injuries or those with minimal effect to parenchymal cell
tissue is restored to prior state
most commonly occurs in epithelial tissue
i.e mild insect bite
tissue regeneration
replaces lost cells by division of surviving adjacent cells, also to restore tissue to normal
before it can occur necrotic cells must be removed (using acute inflammatory process)
whether tissue regeneration can occur?
• Damaged tissues and cells releasing growth factors to decrease mitogenic activity (mitosis)
•regenerative capacity of involved cells
•number of surviving viable cells
• the presence of a connective tissue framework that will provide a base for normal tissue structure
Labile cells regeneration ability?
constant turn over (skin cells)
Stable cells regeneration ability?
usually stop growing once growth i.e. liver, kidney & lungs
requires supportive framework if damage occurs
Fixed (permanent) non-dividing cells regeneration ability?
cannot undergo mitosis
i.e nerve, muscle & cardiac
tissue repair leaves a scar
connective tissue repair stages
acute (hours) : bleeding
acute —> sub acute (days): inflammation
sub acute (days —> weeks) : remodelling
chronic (months): proliferation
bleeding phase
occurs following injury
relatively short lived
more vascular tissue bleeds for longer (muscle)
less vascular less volume & duration (ligaments)
average is 4-6 hours but some bleed for much longer
inflammatory phase
occurs in first few hours
reaches peak at 1-3 days
resolves in few weeks
changes in blood flow
- oedema exudation of protein rich fluid
- phagocytosis
- lymphatic drainage
- leukocyte emigration
proliferation phase
24-48 hours after injury
can take up to a few weeks/ months
fibroblasts, macrophages and blood vessels proliferate to form granulation tissue
two fundamental processes: angiogenesis & collagen synthesis
remodelling / maturing phase
begins at 3 weeks can last up to 2 years
continuous remodelling of scar tissue
physical stress is an important influencing factor in this stage
factors that affect wound healing
• nature of injury
• site of injury
• temperature
• drugs (steroids)
• ** movement +- (stress)**
• malnutrition
• blood flow and O2 delivery
• infection
• wound separation
• foreign bodies
• age
complications of tissue repair
Infection
ulceration
dehiscence
keloid development
adhesion
soft tissue healing summary
• sprains affect ligament
• strains affect muscles & tendons
• connective tissue repair has 4 stages
• if wound edges are approximated it will heal by primary intention
• if wound edges are seperate it will heal by secondary intention (same stages but will take longer and create greater scar tissue)
