Pathphysio

• Cell aging


  An inherent self-destructive mechanism that increases with a person's age
• Factors that affect cell aging

  • Intrinsic factors
  • Extrinsic factors
• Homeostasis


  A dynamic, steady state of internal balance
• Homeostasis


  • Every cell in the body is involved in maintaining it
  • When an external stressor disrupts it, illness may occur
• Structures in the brain responsible for maintaining homeostasis

  • Medulla oblongata
  • Pituitary gland
  • Reticular formation
• Feedback mechanisms that maintain homeostasis

  1. Sensor mechanism

  2. Control center

  3. Effector mechanism
• Negative feedback mechanism


  Works to restore homeostasis by correcting a deficit within the system
• Positive feedback mechanism


  Hormone secretion triggers additional hormone secretion, indicating a trend away from homeostasis
• Disease


  Occurs when homeostasis isn't maintained
• Illness


  Occurs when a person is no longer in a state of normal health
• Factors that influence the course and outcome of a disease

  • Genetic factors
  • Unhealthy behaviors
  • Stress
  • Patient's perception of the disease
• Intrinsic cause of disease

  Disease occurs because of a malfunction or change within the body
• Extrinsic cause of disease


  Disease comes from outside the body
• Examples of extrinsic causes of disease


  • Infectious agents
  • Mechanical trauma
  • Smoking
  • Chemical exposure
  • Nutritional problems
  • Drug use
  • Temperature extremes
  • Radiation exposure
  • Psychological stress
• Stages of disease development

  • Exposure or injury
  • Latent or incubation period
  • Prodromal period
  • Acute phase
  • Remission
  • Convalescence
  • Recovery
• Alarm stage (stress response)


  Body senses stress, CNS is aroused, body releases chemicals to mobilize the fight-or-flight response
• Resistance stage (stress response)

  Body either adapts and achieves homeostasis or fails to adapt and enters the exhaustion stage, resulting in disease
• Exhaustion stage (stress response)

  Body fails to adapt, resulting in disease
• Organelles


  Contained in the cytoplasm and surrounded by cell membrane
• Nucleus


  Responsible for cellular reproduction and division, stores DNA

  
• Other cell components


  • Adenosine triphosphate
  • Ribosomes and endoplasmic reticulum
  • Golgi apparatus
  • Lysosomes
• Cell reproduction


  1. Mitosis (nucleus and genetic material divide)

  2. Cytokinesis (cytoplasm divides)

  
• Cell division phases


  • Prophase
  • Metaphase
  • Anaphase
  • Telophase

  
• Types of cell adaptation

  • Atrophy
  • Hypertrophy
  • Hyperplasia
  • Metaplasia
  • Dysplasia

  
• Types of cell injury

  • Toxic injury
  • Infectious injury
  • Physical injury
  • Deficit injury
• Toxic injury can be endogenous or exogenous
• Physical injury can be thermal or mechanical
• Deficit injury is a lack of basic requirement
• Negative feedback mechanism senses change and returns it to normal
• Positive feedback mechanism exaggerates change
• Disease is influenced by genetic factors, unhealthy behaviors, personality type, and perception of the disease
• Disease manifests in various ways depending on the patient and their environment
• Signs and symptoms of disease include increase or decrease in metabolism or cell division, hypofunction, hyperfunction, and increased mechanical function
• Stressors can be physiologic or psychological
• A deficit may result from a one-way ticket
• Normal blood flow across heart valves

  1. Valves open and close in response to pressure gradient

  2. When pressure in proximal chamber exceeds pressure in distal chamber, valves open

  3. When pressure in distal chamber exceeds pressure in proximal chamber, valves close

  4. Valve leaflets/cusps are so responsive that even a pressure difference of less than 1 mm Hg will open and close them
• Valvular disease


  • Major cause of low blood flow
  • Diseased valve allows blood to flow backward across leaflets that haven't closed securely (regurgitation)
  • Backflow of blood through valves forces heart to pump more blood, increasing cardiac workload
  • Valve opening may become restricted by calcium buildup and impede forward flow of blood (stenosis)
• Valvular disease


  • Heart may fail to meet tissues' metabolic requirements for blood and fail to function as a pump
  • Circulatory system may fail to perfuse body tissues, and blood volume and vascular tone may be altered
• Body's monitoring of blood volume and vascular tone

  • Microvessels measure how much blood each tissue needs and control local blood flow
  • Nerves that control circulation also help direct blood flow to tissues
• Heart's response to tissues' demands

  It responds to the return of blood through the veins and to nerve signals that make it pump the required amounts of blood