Unit 2: Principles of Pathophysiology Flashcards
Pathophysiology
A combination of pathology and physiology.
- The study of the cause of disease process, the result of disease process, or other associated physiological impacts from a disorder or condition.
- As an occupational therapist, you must be aware of the underlying causes of a disorder and the typical process the body goes through when affected by a disorder.
Any time we are introduced to a new pathogen, our bodies undergo…
A specific cascade of events that results in an immune system response that either protects us from illness or creates symptoms as a result of illness.
- It is important to understand the body’s ongoing internal mechanisms when it is exposed to a pathogen in order to know what is a typical response and an atypical response.
- This also helps to understand what stage of an immune response a person is in when we interact with them.
- Even though the immune response can vary slightly from person to person, the general progression of events is typical and predictable.
Our body’s immune system is…
Complex on a systematic and cellular level.
What is the immune system?
The body’s defense system: Comprised of a network of cells, tissues, and organs that work together to defend the body against harmful bacteria, viruses, and other germs. When working properly, identifies and detects a wide variety of pathogens, distinguishes them from the body’s normal healthy tissue, and attacks the abnormal pathogen.
How does the immune system work?
Prevents infection by using innate and adaptive mechanisms to detect and eliminate pathogens.
The Innate Immune System
Typically the first line of defense against a pathogen and includes all aspects of the immune system that are built into the body structures. (ex. the epithelial cell layers, the gastrointestinal tract, and bioactive molecules that are naturally present in biological fluids)
Some aspects of the innate immune system are active all the time and some are activated after an invasion is detected. These are generalized responses built into body structure.
The Adaptive Immune System
Response typically becomes prominent after several days. The adaptive response reacts specifically to the type of invasion detected by the immune system.
- During an adaptive response, the body uses antigen receptors to identify the type of invasion and then releases a defense specific to the invasion.
- Synergy between these two systems is what makes up a healthy and fully effective immune response.
Why is it important for occupational therapists to understand the immune system?
Disorders of the immune system can result in inflammatory diseases, cancer, and autoimmune diseases. Additionally, some clients may have immunodeficiencies such as HIV/AIDS or those that are caused by certain genetic diseases. It is important to understand normal immune response in order to recognize the abnormal responses associated with disorders of the immune system. For example, individuals with autoimmune disorders have abnormal immune responses in which the body’s immune system attacks normal, healthy cells and tissues. Common autoimmune diseases include diabetes mellites type 1, celiac disease, rheumatoid arthritis, and multiple sclerosis.
Phases of the Adaptive Immune Response
- Innate Immune System
- Actute Inflammatory Response
- Antigen Presentation
4a. Humoral Immunity
4b. Cell Mediated Immunity
- Innate Immune System (Phases of the Adaptive Immune Response)
A rapid, non-specific cellular response resulting in a chemical response and an acute inflammatory response.
- Usually begins within 4 hours of a pathogen being introduced.
- Phagocytes: Important part of this process and work to recognize pathogens and destroy them. They also play a role in helping the body to mediate its response to a pathogen.
- Natural killer cells: also part of the initial activation and destroy any cell that they determine to be foreign to the body.
- Complement activation: cascade activation of various pathways that lead to the generation of C3 convertase. This process provides bacterial immunity.
- Acute inflammatory response (Phases of the Adaptive Immune Response)
This response works to contain the infection and usually occurs within 9-96 hours after onset. The response includes:
- Vasodilation and increased blood flow leading to erythema and warmth.
- Increased vascular permeability which results in swelling.
- Bradykinins and prostaglandins are released casuing increased pain sensitvity and hyperalgesia
- Microvascular coagulation occurs to confine the infection
- Systemic features appear such as fever and inflammatory markers which can result in ‘flu-like’ symptoms
- Antigen Presentation (Phases of the Adaptive Immune Response)
This is a specific immune response and involves the activation of T helper cells via the lymph nodes.
4a. Humoral Immunity (Phases of the Adaptive Immune Response)
This specifc adaptive response leads to production of B cells and antibodies. This type of response is best suited for extracellular infections such as bacteria, fungi, protozoans, and parasites.
4b. Cell-Mediated Immunity (Phases of the Adaptive Immune Response)
This specific adaptive response leads to production of antigen presenting cells and cytotoxic T Cells. This type of response is best suited for intracellular infections such as viruses, some bacteria and fungi, and protozoans.
Inflammation
The body’s response to injury.
- Injuries can occur due to physical trauma, bacterial or viral infections, heat, or chemical injury.
- When our body experiences an injury, an acute inflammatory response occurs as the body works to repair and regenerate the damaged structures.
- It is important to understand the concepts of healing and inflammatory response in order to optimize normal and healthy healing while simultaneously identifying and preventing potentially abnormal healing.
- 3 stages of inflammation and the typical response of the body during healing.
Phase 1 of Inflammation
When an acute injury occurs, the body’s immune system responds with an acute vascular and cellular inflammatory response.
- Body immediately increases blood flow to the injured area and mobilizes cells to the area in order to initiate healing.
- Damaged cells are removed, and body begins to deposit collagen in the area of the injury. This collagen deposit is what causes edema or acute swelling.
- This phase is initiated immediately after tissue damage and lasts approximately 3-5 days depending on severity of injury.
- If an injury is ongoing or chronic, the inflammatory response may be chronic.
- In this case the signs and symptoms listed below may be present for a longer period of time and the individual is at higher risk of developing permanent tissue damage or fibrosis.
- Signs and symptoms of an inflammatory response to injury include pain, warmth, swelling, tenderness, and limited joint or tissue mobility.
- The focus of OT involvement at this phase is to reduce pain and edema, prevent chronic inflammation, and maintain mobility and strength in the surrounding areas.
Phase 2 of Inflammation
The second phase of healing involves repair and regeneration.
- The body deposits new collagen fibers around the area, forming a scar.
- These tissues are laid down in a disorganized manner and often this tissue is weak and susceptible to reinjury with too much activity or movement.
- New tissue may take 2 days to 8 weeks to heal.
- Warmth, tenderness, and swelling should decrease during this phase but there is a risk for over development of scar tissue that can impact function in the future.
- OT intervention typically focuses on the prevention of scar tissue build up, range of motion, joint mobilization, and stretching of tissue.
Phase 3 of Inflammation
The third phase of healing involves remodeling and maturation of tissue.
- This phase may take months to years for completion and involves remodeling and strengthening of the cellular organization of collagen fibers.
- The focus in this stage is range of motion, stretching, and strengthening.
