Module 5- Altered healing and mobility

Question 1

How can bed rest affect the body

Answer 1

Decreases the use of muscles and the effects of gravity resulting in kidneys diuresis, changes in lung ventilation and cardiovascular deconditioning
Can reduce muscle and bone mass and cause pressure injuries

Question 2

What is the acute inflammatory response

Answer 2

Most common form of response, takes around 8-10 days (part of innate immune response)
Defence mechanism of the body
Inflammation is triggered by cells that recognise pattern of molecules associated with cellular damage or pathogens

Question 3

List the first step of acute inflammatory response

Answer 3

Entry of foreign molecule e.g. bacteria into the body resulting in tissue damage

Question 4

List the second step of the acute inflammatory response

Answer 4

Mast cells stimulated to release chemical mediators (rapid response within seconds to minutes) which triggers three main actions:

• Vasodilation: increases vessel diameter slowing blood flow and increasing volume of blood flow, allowing for increased inflammatory cells and chemicals to area of injury - leads to swelling and pain
• Increased vessel permeability: retraction of endothelial cells lining vessels causes gaps to open up between these cells allowing leakage of plasma out of vessel (exudation) which causes swelling (oedema). Blood becomes more viscous and flows slowly which increases blood volume and conc. of red blood cells at site of inflammation - causes heat and redness
• Diapedesis and chemotaxis: white blood cells (e.g. leucocytes) adhere to inner walls of capillaries and migrate through enlarged junctions between endothelial cells lining vessels into the surrounding tissue - attracts inflammatory cells such as phagocytes which cause phagocytosis

Question 5

List the third step of acute inflammatory response

Answer 5

As a result of changes to blood vessels the signs of inflammation are observed:
Redness: increased blood flow from vasodilation and increased permeability
Heat: increased blood flow (blood=warmth)
Swelling: increased blood flow from vasodilation and increased vessel permeability - increased fluid and blood cells to region
Pain: swelling effects leads to increased fluid in region which activates pain receptors, inflammatory mediators also directly activate pain receptors

Question 6

Describe histamine

Answer 6

Vasoactive amine that acts on blood vessels. Come from platelets, mast cells and basophils and cause increased vasodilation, vascular permeability, vascular smooth muscle contraction and endothelial activation

Question 7

Describe serotonin

Answer 7

Come from platelets and causes vasodilation and increased vascular permeability

Question 8

Describe prostaglandin

Answer 8

Come from mast cells and leucocytes, cause vasodilation, pain, chemotaxis and fever

Question 9

Describe Leukotrienes

Answer 9

Come from leucocytes and mast cells, causes increased vascular permeability, chemotaxis, leucocyte adhesion and activation

Question 10

Describe platlet-activating factor

Answer 10

Come from leucocytes and mast cells, cause vasodilation, increased vascular permeability, leucocyte adhesion, chemotaxis and degranulation

Question 11

Describe nitric oxide

Answer 11

Come from endothelium and macrophages, cause vascular smooth muscle relaxation and killing of microbes

Question 12

Describe cytokines

Answer 12

Come from macrophages, endothelial cells and mast cells, cause local endothelial activation, fever, pain, hypotension, decreased vascular resistance (shock) - common ones include Interleukins and interferons

Question 13

Describe chemokines

Answer 13

Come from leucocytes and activated macrophages, cause chemotaxis, recruitment of leucocytes to sites of inflammation and migration of cells to normal tissues

Question 14

Describe tumor-necrosis factor alpha

Answer 14

Strong mediator of fever

Question 15

Describe wound healing

Answer 15

Begins during acute inflammation and can last up to 2 years
Wounds that heal under conditions of minimal tissue loss e.g. paper cut, are said to heal by primary intention
Wounds that do not heal as easily e.g. pressure injury, are said to heal by secondary intention

Question 16

What are the steps of wound healing

Answer 16

1. Inflammation
2. Reconstructive/proliferative phase
3. Maturation/remodelling phase

Haemostasis can also be described as first step, then the others follow (controlling the bleeding)

Question 17

How long do wound healing phases last

Answer 17

Haemostasis initial injury to 3 hrs post injury
Inflammation is 4-6 days
Proliferation is 4-24 days
Remodelling is 21 days - 2 years

Question 18

Explain the second wound healing phase- reconstructive/proliferation

Answer 18

Macrophages invade dissolving the clot and clear away dead cells and debris, also secrete biochemical mediators that promote healing
Granulation tissue (connective tissue and fibroblasts) grows into wound from surrounding healthy connective tissue which leads to fibrosis
Tissue is filled with new capillaries (process called angiogenesis – meaning growing new blood vessels) derived from capillaries in surrounding tissue which gives tissue red, granular appearance
New lymphatic vessels also grow, as well as an additional extracellular matrix which provides a scaffold to guide cell placement, proteins also direct some cellular functions related to wound healing

Question 19

How is healing protected during second phase

Answer 19

Through epithelialisation which is where epithelial cells grow into the wound from surrounding healthy tissue

Question 20

Explain epithelialisation

Answer 20

Epithelial cells do the following:
- Migrate under clot or scab to unravel collagen
- Contact similar cells from all sides of wound and seal it to halt migration and proliferation
-Undergo differentiation to give rise to epidermal layers
Epithelialisation can be quick process if wound is kept moist as it keeps fibrin clot from becoming a scab

Question 21

What are the most important cells during healing phase

Answer 21

Fibroblasts are most important cells during healing as they secrete collagen and other connective tissue proteins, which are deposited in debrided areas about 6 days after fibroblasts have entered the lesion
Collagen is the most abundant protein in the body (high conc. of amino acids) - as healing progresses, collagen undergoes chemical reactions to form collagen fibres (complete process takes several months)

Question 22

What is wound contraction

Answer 22

Occurs during second phase of healing process
Wound contraction needed to close wounds (especially those by secondary intention) – noticeable 6-12 days after injury
Granulation tissue contains myofibroblasts (cells specialised for wound contraction (shortening)- functions of both smooth muscle cells and fibroblasts)
Contraction occurs as extensions from plasma membrane of myofibroblasts establish connections between neighbouring cells exerting tension while anchoring themselves to wound bed

Question 23

Explain the maturation/remodelling phase of wound healing

Answer 23

Continuation of collagen matrix assembly, tissue regeneration
Scar tissue remodelled and capillaries disappear making scar avascular
Takes 2-3 weeks after maturation begins for scar tissue to gain 2/3 of maximum strength
Epidermal secondary intention healing wounds and un-sutured internal lesions not completely restored by healing (at best gains 80% original strength)
Only epithelial, liver and bone marrow are capable of regaining complete strength (this is called compensatory hyperplasia)
In fibrous connective tissue joints and ligaments, injured tissue is replaced with new tissue, however, does not have exactly same structure and function as original tissue (why it can easily become re injured)

Question 24

Difference between resolution and repair

Answer 24

Resolution: returning injured tissue to the original structure and function
Repair: replacement of destroyed tissue with scar tissue (composed primarily of collagen to restore the tensile strength of the tissue)

Question 25

Explain primary intention wound healing

Answer 25

Wounds that heal under conditions of minimal tissue loss
Include clean incisions such as paper cut or sutured surgical wound
Heal primarily through process of collagen production
Close proximity of wound edges
Little sealing (epithelisation) and shrinkage (contraction)
Original tissue structure and function restored (capable of regeneration)

Question 26

Explain secondary healing intention

Answer 26

Wounds that require a great deal more tissue replacement
- Open wounds
- Do not heal as easily- healing process takes longer
- Wounds usually contain extensive tissue loss such as a pressure injury
- Processes take longer
- Tissue cannot regenerate so results in a scar
Example: pressure ulcer

Question 27

How are antihistamines used for wound healing

Answer 27

Stop binding of histamine to receptors, therefore, decrease inflammation

Question 28

How is aspirin and other NSAIDs used for wound healing

Answer 28

Block production of prostaglandins inhibiting inflammation, and reducing pain and fever

Question 29

How can wound healing be dysfucntional during reconstruction phase

Answer 29

Impaired collagen synthesis (keloid scar and hypertrophic scar)
Impaired epithelisation (anti-inflammatory steroids, hypoxaemia and nutritional deficiencies)
Impaired contraction (contracture)
Wound disruption:
- Dehiscence- wound pulls apart at suture line, excessive strain and obesity can be causes, and increases risk of wound sepsis

Question 30

Which cells in epidermis initiate immune responses and provide protection against environmental antigens

Answer 30

Langerhans cells

Question 31

What is the term for skin lesions that are elevated, rounded and firm with irregular margins extending beyond site of initial injury

Answer 31

keloid

occur due to excess collagen

Question 32

What is the first sign of pressure injury and what dressings should be applied to them

Answer 32

Nonblanchable (don’t have to touch it or apply pressure) erythema of intact skin
Flat and moist dressings

Question 33

What is deep vein thrombosis

Answer 33

When a blood clot develops deep in a vein

Can happen with bed rest

Question 34

Describe haemostasis stage of wound healing

Answer 34

Adrenaline (vasoconstrictor) released to stop bleeding
Platlet cells aggregate (clot) and cytokines released (line up around wound border). Cytokines call in other cells to help with later phases.
CONTROLS BLEEDING

Question 35

What is a scab

Answer 35

platelets and red blood cells which have clotted

Question 36

What causes itching of a wound

Answer 36

Angiogenesis (development of new blood vessels) causes itching which is caused by histamine