Pathophysiology UNRS 367 PDF

UNRS 367: PATHOPHYSIOLOGY KATIE MEYER MSN, RN, PHN, CCRN-K, NHDP-BC ADAPTED FROM THE SLIDES FROM LORI J. SILAO, PHD, RN, MN, NNP-BC QUESTION FOR THOUGHT What is pathophysiology and why is it important for clinical practice? ANSWER: Let’s Define It: Physiology- the s...

UNRS 367: PATHOPHYSIOLOGY KATIE MEYER MSN, RN, PHN, CCRN-K, NHDP-BC ADAPTED FROM THE SLIDES FROM LORI J. SILAO, PHD, RN, MN, NNP-BC QUESTION FOR THOUGHT What is pathophysiology and why is it important for clinical practice? ANSWER: Let’s Define It: Physiology- the study of specific characteristics and functions of living organisms Physis- Nature Pathos- (Greek) suffering or disease Therefore: Pathophysiology is the study of disease or disorder of the human body PATHOPHYSIOLOGY Can we break these down?  Homeostasis  Disease  Illness  Epidemiology (endemic, epidemic, pandemic)  Allostasis QUESTION FOR THOUGHT: How might disease interrupt homeostasis? HOMEOSTASIS Homeostasis and Systems Control Homeostasis refers to stable operating conditions in the internal environment (in the blood and interstitial fluid). This is how the human body maintains a rather constant internal environment despite changing external conditions It is brought about by coordinated activities of cells, tissues, organs, and organ systems HOMEOSTASIS Homeostasis requires three components: 1. Sensory receptor cells detect specific changes (stimuli) in the environment. 2. Integrators (brain and spinal cord) act to direct impulses to the place where a response can be made. 3. Effectors (muscles and glands) perform the appropriate response* *Think GAS (General Adaptation Syndrome)  A common homeostatic mechanism is negative feedback. It works by detecting a change in the internal environment that brings about a response that tends to return conditions to the original state. It is similar to the functioning of a thermostat in a heating/cooling system. Some activity alters a condition in the internal environment. The alteration triggers a response. The response reverses the altered condition. Think self-regulation!  Again, the variable to be controlled must be “sensed” to be regulated, examples: 1. When body temp. deviates from normal, negative feedback restores homeostasis. The temp. (variable) is “sensed” and the body responds by sweating.  Another example: High blood glucose levels (variable) is “sensed” and the body responds by increased insulin production by the pancreas, returning blood glucose levels to normal, thus maintaining homeostasis.  Another (less common) form of feedback for homeostatic maintenance In positive feedback, some activity alters the internal environment. The alteration triggers a response. The response intensifies the change in the internal condition. Positive feedback mechanisms may intensify the original signal. Only a few positive feedback examples operate in the body under normal conditions: 1. Birth of a baby 2. Formation of a blood clot  Contraction – oxytocin – nerve stimulus – hypothalamus – oxytocin - contraction….repeat! Injury – signals – platelets – more signals – rapid cascade – blood clot….repeat! Can you find one more example?  The study of the cause or reasons for phenomena (In this case, a disease) A description of etiological process includes the identification of those causal factors that provoke the disease  Idiopathic: Iatrogenic: The cause of the illness or disease is The cause of the illness or disease is unknown from a medical treatment or medical professional  Infectious Inherited Iatrogenic Congenital Psychogenic Metabolic Idiopathic Degenerative Nutritional deficiency Neoplastic Physical-agent Immunologic Psychosomatic: old school term, not used anymore, carries a stigma.  The development or evolution of disease (think initial stimulus to the ultimate expression) Varies with the causative agent and type of cell, tissue or organ affected  Time Quantity Location Morphologic changes  Time: the disease can be in its early or late stages OR the disease process may be acute or chronic Quantity: offering an amount of the infective agent; can be slight, moderate or marked  Location: where in the body the invasion/illness is present Morphologic Changes: the structural and associated functional alterations in cells or tissues that are either characteristic of the disease or diagnostic of the etiological process  Primary: reducing susceptibility or exposure to disease or illness Secondary: the early detection, screening and managing of a disease Tertiary: includes rehabilitative and supportive care 1. What role does stress play in the development of disease? General Adaptation Syndrome Spring 2015 23 23 24 Spring 2015 24 24 Cathecholamines Norepinephrine: Constricts blood vessels and raises blood pressure Reduces gastric secretions Increases night and far vision Epinephrine: Enhances myocardial contractility, increases heart rate, and increases cardiac output Causes bronchodilation Increases the release of glucose from the liver (glycogenolysis) and elevates blood glucose levels Adrenocortical Steroids: Critical to maintenance of homeostasis May synergize or antagonize effects of catecholamines Examples: Cortisol and aldosterone Cortisol: Primary glucocorticoid Affects protein metabolism Promotes appetite and food-seeking behaviors Suppress acute-phase response to inflam. by decreasion overactivity. Helps preserve glucose for brain cells. Aldosterone Primary mineralocorticoid Secreted by adrenal cortex, binds to kidneys distal/collecting ducts. Promotes the reabsorption of Na & H20 Increases blood pressure Spring 2015 Immune Cytokines: Secreted by macrophages during stress response Enhance immune system response Prolonged stress can suppress immune functioning Endorphins, Enkaphalin: Small peptides, endogenous opioids produced within the CNS. Release in response to stressors, certain foods (chocolate), laughter, massage, accupunture. Increase pain threshold (lowers pain). Produces sedation as well as euphoria. Growth Hormone (GH): Released from the anterior pituitary Increased secretion during strenuous exercise Extreme stress leads to decrease in GH (i.e.chronic illness, children under severe abuse). Prolactin: Released from the anterior pituitary Secreted in response to stress, sexual activity, suckling (men included), breastfeeding. Oxytocin: Secreted from anterior pituitary Childbirth, lactation, sexual behavior. Promotes bonding and social attachment. HOMEOSTASIS VERSUS ALLOSTASIS CELLS What do you remember about what cells do? Draw a cell and any of the components you remember about a cell.  What are the major cellular structures and their functions? Plasma Membrane Cytoskeleton Nucleus Endoplasmic Reticulum Golgi Apparatus Lysosomes & Peroxisomes Mitochondria CELLULAR STRUCTURE AND FUNCTION REVIEW  According to the accepted current theory, known as the fluid mosaic model, the plasma membrane is composed of a double layer (bilayer) of lipids, oily substances found in all cells. Most of the lipids in the bilayer can be more precisely described as phospholipids. Phospholipids are characteristically hydrophilic ("water-loving") at their phosphate ends and hydrophobic ("water-fearing") along their lipid tail regions. Plasma Membrane’s Functions Transport nutrients and waste products Generate membrane potentials Cell recognition and communication Growth regulation Sensor of signals that enable cell to respond and adapt to changes in environment.  The cytoskeleton provides both the supporting structure of the cell and the vehicle for internal transport processes. It is a network of long protein filaments, mainly microtubules, actin filaments and intermediate filaments, coupled by smaller proteins, such as motor proteins. Motor proteins are molecular machines that convert chemical energy derived from the hydrolysis of ATP (Adenosine TriPhosphate) into mechanical work, generating forces and motion of the filaments relative to each other in this complex fluid.  The cell nucleus is one of the largest organelles found in cells and also plays an important biological role. It composes about 10% of the total volume of the cell and is found near the center of eukaryotic cells. Its importance lies in its function as a storage site for DNA, our genetic material. The cell nucleus is composed of two membranes that form a porous nuclear envelope, which allows only select molecules in and out of the cell.  The DNA that is found in the cell nucleus is packaged into structures called chromosomes. Chromosomes contain DNA and proteins and carry all the genetic information of an organism. The nucleus gains support from intermediate filaments that both form the surrounding nuclear lamina and makes direct contact with the endoplasmic reticulum. The nucleus is also the site of DNA and RNA synthesis. Spring 2015  The endoplasmic reticulum plays a role in both the transport of large molecules in the cytoplasm and protein synthesis. The ER is divided into two different parts: The rough and the smooth ER. The two, together, make up over half of a cell membrane and extend through the cytoplasm to the nuclear membrane. Central role in synthesis of membrane components. Rough and smooth types. Rough: coated with ribosomes, complexes of protein, and RNA Smooth: lacks ribosomes; involved with lipid metabolism  The Golgi apparatus is a part of the membrane system within the cell as well and works closely with the endoplasmic reticulum. The Golgi Apparatus modifies proteins and brings them to the cell surface where they can be secreted. Secretions hormones, enzymes, antibodies and other molecules.  Lysosomes are membrane bound vesicles whose purpose is to help with the digestion of molecules. They are able to do this because of their acidic interior which contains digestive enzymes. They also make sugars, amino acids, and bases which help create the foundation of the very macromolecules they digest  Like Lysosomes, these are membrane bound sacks of enzymes Particularly important in liver and kidney cells Detoxify substances such as alcohol  Known as the cell’s “powerhouse” Mitochondrial proteins are responsible for cell respiration and the synthesis of ATP that provides cellular energy. Enzymes in the cell catalyze chemical reactions. Storage vesicles contain and release hormones and neurotransmitters. They act on receptors and control ion channels. In this way cells can communicate with each other and order proteins in the cell to work in concert with the entire organism. Programmed cell death called apoptosis  Cell energy or metabolism, is the process by which individual cells process nutrient molecules. Metabolism has two distinct divisions: catabolism, refers to the energy-releasing breakdown of nutrient sources such as glucose to provide ATP to the cell, anabolism, refers to energy-using metabolic processes or pathways that result in the synthesis of complex molecules such as fats. Both these processes require long, and complex series of enzymatic steps.  Once inside the cell, glucose is broken down to make adenosine triphosphate (ATP), a form of energy, via two different pathways. The first pathway, glycolysis, requires no oxygen and is referred to as anaerobic metabolism. Each reaction is designed to produce some hydrogen ions that can then be used to make energy packets (ATP). In prokaryotes, glycolysis is the only method used for converting energy. The second pathway, called the Krebs cycle, or citric acid cycle, occurs inside the mitochondria and is capable of generating enough ATP to run all the cell functions.  How are substances transported across the cell membrane?