SOURCES: Week 1, Public Health – Introduction to burns Case 1,  Mpho Tlali 

Specialised Cells: (Histology Slides)

perineum: thin skin
partial thickness=second degree=epidermis and dermis

keloid

https://youtu.be/p4hnFf_jmvU
https://youtu.be/qmR1Sk-b4Bs

 

CHANGE IN FUNCTION 

– Loss of fluid and electrolyte balance: massive fluid loss (Treatment – fluids and electrolytes) – Reduced thermoregulation: increased fluid loss means evaporative cooling and more energy needed to keep up body temperature (Treatment: keep warm, extra nutrients) – Reduced protection from infection: widespread bacterial infection or sepsis (Treatment: antibiotics, skin graft. 

CHANGE IN STRUCTURE 

Some burns may leave permanent scars and/or keloids. During keloid formation, there is a prolonged inflammatory phase (due to immune cell infiltration into the scar tissue).  Leads to excess fibroblast activity and increased deposition of the extracellular matrix (ECM), resulting in the tissue projecting beyond the original wound margin.

case: stayed for 4 weeks (28 days), anesthetised. leg=mixture of thicknesses (the leg is red-1st, blistered-2nd, and black-3rd), all layers of skin irreversibly damaged. perineum=partial thickness (2nd)

treatment: skin autograft

Source: Histology of the skin , slide 44-48
Histology of the Skin (uct.ac.za)

 

 

·         Biological barrier - Langerhans cells, chemokines, cytokines, keratinocytes, phagocytes- The skin also has an immune response to microorganisms through the transient T lymphocytes and Langerhans cells, which stimulate T-cells and are involved in the immune response.

·         Chemical - Salt, acid mantle - The sweat released by the skin contains salt and is acidic and antibacterial.  The melanocytes in the skin, but particularly melanin provides protection against UV radiation from the sun as a result, protects deeper tissues from damage. The sebum released by the sebaceous glands releases bactericidal substances.

·         Mechanical barrier - skin is intact- keratinized (keratin layer is a tough fibrous protein) stratified squamous epithelium of the epidermis. Waterproof (by Lamellar granules. Keratinocytes produce lamellar granules) -prevent uptake or loss of fluids through the skin. The epidermal layer (stratum germinativum layer) has mitotically dividing stem cells; when cells are lost due to friction or abrasion they are replaced. 

stratified and keratin: protection function

Ø  The number and type of different receptors(exteroceptors) located in the dermis and epidermis relate to its function as a sensory organ (it is the largest sensory organ in the body). Each cell type is receptive to a certain cutaneous sense (either pain, pressure, temperature, touch) 

Ø  Enables nervous system to perceive changes in body’s internal or external surroundings; Receptors detect potentially harmful stimuli (heat, cold, and pain) that could lead to tissue damage; this is critical for maintaining homeostasis

·         The large vascular supply of the skin is conducive to its thermoregulation function. By increasing the flow rate, more heat can be lost, thus controlling body temperature.

·          The layer of subcutaneous fat also acts as an insulator to keep heat in.

·          The hair on the surface of the skin also acts as an insulator.

·          Changes in body temperature in either direction alter cell activity – an increase in temperature causes and increase or decrease cellular reactions and vice versa. Because cells are so sensitive to changes in temperature, the body homeostatically maintains its temperature. Exposure to extreme conditions can affect the core temperature. Heat input must match heat output to maintain thermodynamic balance, and a stable core temperature. 

·         Heat input can either be due to internal heat generation (muscle movement or metabolism) or heat gained from the external environment. 

·         Heat loss is heat lost via the exposed body surfaces to the external environment. Heat exchange with the external environment takes place via either: radiation, convection, conduction and evaporation.

·          The hypothalamus is the body's thermostat. It receives information from various afferent inputs and initiates adjustments to heat gain and heat loss mechanisms to correct the core temperature from variations from normal. The hypothalamus monitors the core and peripheral temperatures via various thermoreceptors. 

Ø  The posterior region of the hypothalamus is activated by cold, triggering reflexes that mediate heat production and heat conservation. 

Ø  The anterior region is activated by warmth, triggering reflexes that mediate heat loss.

Ø   Heat promoting mechanisms: Constriction of the cutaneous vessels: blood vessels in skin are constricted, keeping blood in the deeper body areas. The subcutaneous layer insulates – preventing heat loss from deep tissues Shivering: rhythmic muscle contractions that generate heat. These muscles can generate up to 5 times the amount of heat as resting muscle. Behavioural modifications: wear warmer clothes, engage in physical activity, reduce exposed body surface area, drink hot fluids] 

Ø  Heat loss mechanisms: Dilation of cutaneous vessels: blood vessels in the skin dilate, increasing blood flow to the skin surface. Heat is lost via radiation, convection and conduction Enhanced sweating: increased blood flow to skin stimulates sweat glands, secretory output is increased, and heat loss through evaporation increases. Stimulation of respiratory centres: respiratory centres in the medulla are activated, depth of respiration increased, breathing through mouth rather than nose. This increases evaporative heat loss through lungs. Behavioural modifications: seek a cooler environment, drink cool fluids, reduce activity, wear lighter, cooler clothing. 

Blood reservoir:

·         The skin is highly vascularised and contains 5% of the total blood volume (TBV).

·         It uses this relatively large TBV% to control thermoregulation. 

·         Shunt blood to areas that demand it if necessary 

·         Excrete salt, water, and nitrogenous waste through sweat glands

·          Limited absorptions: UV light ,Salts of heavy metals ,Lipid soluble substances, Organic solvents

Metabolic functions: 

·         Keratinocytes inactivates certain carcinogens and activates certain steroid hormones

·          Skin makes important proteins such as antioxidants and collagenase. 

·         Vitamin D synthesis: UV converts cholestrol to inactive vit D, goes to liver, hydroxylated. hydroxylated vit D makes calcitriol in kidneys. calcitriols NB for absorption of Ca2+ and P

·         INSENSIBLE WATER LOSS

Ø  Unnoticeable H2O loss 

Ø   Occurs through lungs, skin, oral mucosa 

Ø  Passive process

·         SENSIBLE WATER LOSS

Ø  Active process 

Ø  Body temperature rises 

Ø  Sweating increases vaporization of water

 

Understand and apply (in various contexts) the definitions of the following measures of extent of disease: 

• Cumulative incidence (incidence risk, incidence proportion) 

- Proportion of disease-free population that become newly affected by the disease over a specified time period. Number of new people who burn/Risk of burning. 
36/10000 for 2018.

Incidence rate (incidence density) 

The rate at which people develop a new disease  

The incidence rate is calculated by dividing the number of new cases over a specific time period by the sum of the length of time which each person is at risk of the disease. Thus it would be the amount of people who burn during a specific time period, divided by the time which they are at risk of burning. 

Prevalence (prevalence rate) 

 Interpret text and tables where these measures are used to describe the extent of disease. 

Prevalence is the measure of the amount of people who actually have the disease at a particular time ,also known as the disease burden. 

Thus prevalence is the number of existing cases, in this case it would be the number of people who currently burn victims in SA. 

incident (new infections) and prevalent (existing) are numbers, incidence and prevalence are proportions

 [Affinity is the tendency to bind]
Haemoglobin (Hb) transports oxygen in blood from lungs where there is high pO2 (partial pressure of oxygen) to peripheral tissues (low pO2), this is possible due to Haemoglobins high (changes) affinity, at high pO2 (in the lungs) Hb is fully saturated with Oxygen and becomes less saturated in peripheral tissues due to its low affinity enabling it to release oxygen to peripheral tissues.

Haemoglobin also binds to oxygen cooperatively due to conformation changes of the subunits. When one haem binds to oxygen, the affinity of the other haems increase in the lungs at high pO2.

The converse occurs in the peripheral tissues where there is a low pO2, the release of oxygen in one haem increases the tendency for oxygen to dissociate from the remaining haems.

Myoglobin has a high (constant) affinity for oxygen, this allows it to bind to oxygen at low pO2 and have a high oxygen saturation. This is essential as it allows Mb to store oxygen and release it when needed such as during exercise to be used by mitochondria for energy generation. Myoglobin is therefore able to bind and store oxygen released from arterial blood in the peripheral tissues (at low pO2).

Ø  Treatment should use cool running water of 2 – 15 ⁰C for a full 20 minutes

Ø  Ice or icy water should not be applied to burns as this can lead to hypothermia

Ø  Decreased wound depth

Ø  Reduced time for wound re-epithelialisation

Ø  Decreased hospital stay/ visits

Ø  Decreased requirement for grafting and scar management

A.     Decreased pain from damaged nerve endings - blood vessels dilate due to high temperature

B.     Decrease immediate cell death due to high temperatures - proteins denature due to high temperature

C.     Decrease release of cytokines from damaged cells which activate inflammatory cascade

D.     Prevent blood vessels shutting down in zone of stasis and stabilise vasculature 

E.     Prevent release of histamine from activated mast cells 

F.      Decrease or prevent oedema formation - blood vessels being more permeable

 

Resource pack:

Ø  Cooling with cold water is the most widely employed first aid measure and has been shown to reduce the severity of acute symptoms and the need for skin grafting – cooling reduced the clinical and histological depth of burn injury. This cooling temperature and duration consistently reduced blistering, erythema and oedema of the burned skin

Ø  Early cooling with 10 - 20 minutes of cool running water up to 3 hours after a burn has a direct impact on the depth of the burn and therefore on the clinical outcome of the injury.

 

Ø  Early cooling of burns leads to less clinical and histological tissue necrosis, improves burn healing, and helps relieve pain.

Ø  This cooling temperature and duration consistently reduced blistering, erythema, and oedema of the burned skin.

Ø  This phenomenon suggests that the model is dynamic, and that the microvasculature initially remains patent and perfused. It is possible that cooling helps to maintain this perfusion, allowing the survival of more dermis.

Read related literature regarding research topic, searching for ideas and theories based on analysis of theories of how test behavior is likely to change during certain situations (constructs) 

 

Establish construct validity evidence, meaning ensuring that your test are truly measuring the variable that needs to be measured 

Panel of experts should read and review the survey instrument and offer feedback 

 

Test the survey instrument on a similar population, ensuring validity and reliability  

 

Choose sample that is representative of the population that is in question and determine a sample size. 

 

 

Perform survey, after ensuring that the proper authorities have signed off on conducting the trial. 

SOURCES: 

Testing A Research Questionnaire (ukessays.com) 

https://www.bing.com/newtabredir?url=https%3A%2F%2Fwww.thevenusproject.com%2Fmultimedia%2Fthe-scientific-method%2F 

What Are "Peer-Reviewed" Articles? - CHEM 6C: General Chemistry III (Brydges, Spring 2022) - LibGuides at University of California San Diego 

 

 

The public health model of prevention includes four steps, namely:

·         The first line of defense is the epidermis

·         The epidermal surface is made acidic by sweat and sebum, which may contain antibacterial enzymes

·         It provides physical  and chemical (first line of defense) protection

·         The skin has keratinocytes which serve as a barrier

·         It also can initiate immune response

The immune response is divided into two major arms, innate and adaptive immunity.

·         Innate immunity serves as the second line of defense and is a more general response (fever and inflammation).

·         Non- immunological memory responses

·         adaptive immunity allows for a very specific detection and elimination of pathogens and imparts immunological memory. All immune cells develop from a cell in the bone marrow.

Keratinocytes secrete;

·         cytokines which help maturation of T-cells in the epidermis

·         chemokines which attract other cells to the site of infection

Langerhans Cells

·         are responsible for antigen uptake and present antigen to helper T cells

 

B cells

·         Mature B-cells differentiate into plasma cells (secrete antibodies) and memory cells

·         Recognize antigen via B Cell Receptor

 

NK cells

·         Of the innate immune system, detect virus infected cells and kill them

T-cells

·         Memory T-cells help the body to have a faster immune response to future infections

·         Helper T-cells secrete cytokines that boost the adaptive immune response

·         CD4 T(receptor)-cells secrete cytokines which rapidly boost the immune response when a past challenge arises

·         CD8 T (effector) cells recognise virally infected cells and kill them 

 

·         Neutrophils capture and kill microorganisms throughout the body and activate bacterial mechanisms

·         Monocytes further differentiate to give rise to macrophage( tissue resident cells, they control the body in cleaning up infections, antigen presentation and activating other cells) and dendritic cells. Dendritic cells are phagocytic cells that are responsible for antigen uptake and presentation

    Inflammatory mediators

·         The eosinophil release cytokines  and kill antibody coated parasites. 

·         Mast cells release granules contain histamine and active agents -respond to infection or tissue damage

 

Source:

·         Immunology Lecture 1,  Week 1

 

       i.          Primordial (not only disease specific, improvement of societal and structural risk factors)

Ø  Improved living conditions for healthy people by better housing and poverty reduction

Ø  Changing methods of cooking/ heating to reduce use of paraffin and primus stoves

 

      ii.          Primary 

Ø  Health promotion and prevention in healthy, at-risk people of burns

Ø  Safety health promotions

 

    iii.          Secondary 

Ø  Early diagnosis and prompt treatment – first aid treatment

Ø  Neighbours put oil over the burnt area and then called the ambulance

Ø  Multidisciplinary team handles the case further (biopsychosocial)

 

    iv.          Tertiary 

Ø  Prevention of complications –treatment and rehabilitation

Ø  Skin graft

Ø  Temperature monitoring

Ø  Fluid status

Ø  Protein diet

Ø  Family members educated on management after hospital release

Ø  Prevent contractures

Ø  Psychological and social support