Physiology Overview Quiz

Physiology Overview

• Definition: Study of life processes and operation of living systems at molecular, organ, system, and whole organism levels.
• Investigates responses of living systems to physical activity and environmental conditions.

Pathophysiology

• Emphasis on understanding molecular, cellular, and systemic responses to diseases.
• Importance in disease identification, diagnosis, treatment, prognosis, and prevention.

Common Disease Processes

• Inflammation:

  • A complex response to tissue injury/infection with chemical mediators.
  • Chronic inflammation linked to multiple diseases.

• Pathogens:

  • Includes bacteria, viruses, fungi, and parasites causing infectious diseases.
  • Can disrupt normal functions, release toxins, induce inflammation, and damage tissues.

• Cancer:

  • Characterized by uncontrolled cell growth and tissue invasion.
  • Genetic mutations drive abnormal cell division, reduced apoptosis, and angiogenesis.

• Cardiovascular Diseases:

  • Impacts heart and blood vessels, leading to conditions like coronary artery disease and stroke.
  • Pathophysiology includes fatty plaque accumulation leading to atherosclerosis.

• Metabolic Disorders:

  • Result from biochemical process defects affecting energy production/utilization.
  • Often involves hormone level imbalances, glucose metabolism issues, and lipid/protein dysregulation.

• Neurological Disorders:

  • Includes diseases like Alzheimer's, Parkinson's, and multiple sclerosis, affecting neural function.
  • Characterized by neuron loss and impaired communication, resulting in cognitive and motor dysfunction.

Key Terminology

• Disease: A disturbance in bodily structure/function, can be symptomatic or asymptomatic.
• Pathology: Study of structural and functional changes caused by diseases.
• Etiology: The cause of disease.
• Pathogenesis: Sequence of events leading to disease.

Disease Classification

• Congenital/Hereditary: Changes in DNA (e.g., Down syndrome).
• Inflammatory: Body's reaction to harmful agents (e.g., autoimmune diseases).
• Generative: Changes due to aging (e.g., arthritis).
• Metabolic: Disturbances in metabolic processes (e.g., diabetes).
• Neoplastic: Tumor growth, benign or malignant (e.g., cancer).

Cellular Adaptation

• Goal: Maintain homeostasis through adaptation to internal and external environment changes.
• Physiological Adaptations: Example includes uterine enlargement during pregnancy.
• Pathologic Adaptations: Examples: atherosclerotic plaque formation, cardiac hypertrophy due to hypertension.

Types of Cellular Adaptation

• Atrophy: Reduction in cell size due to factors like disuse and ischemia.
• Hypertrophy: Increase in cell size due to increased workload; may be physiological (exercise) or pathologic (disease).
• Hyperplasia: Increase in cell number, occurring in tissues capable of division; can be physiological (hormonal stimulation) or non-physiological (excessive growth factors).
• Metaplasia: Replacement of one cell type by another due to chronic irritation (e.g., squamous to goblet cell transformation).
• Dysplasia: Abnormal cell development, varying in size and shape, associated with inflammation, may lead to cancer.

Cell Injury

• Reversible Injury: Includes membrane blebbing, mitochondrial swelling, cellular swelling.
• Irreversible Injury: Involves lysosomal rupture, phospholipid membrane damage, and significant nuclear changes.

Major Causes of Cell Injury

• Nutritional imbalances, physical agents, radiation, chemical agents, and biological agents can lead to cellular injury.
• Hypoxia: Most common cause of cellular injury, can lead to cell death.
• Ischemia: Reduced blood supply resulting in hypoxia; total lack of oxygen is termed anoxia.

Mechanisms of Cell Injury

• Oxidative Stress: Imbalance between reactive oxygen species (ROS) and antioxidants; can lead to DNA damage and lipid peroxidation.
• Ischemia-Reperfusion Injury: Reactive oxidative species released during tissue reperfusion can exacerbate cell injury.

Chemical Injury

• Exposure to xenobiotics (carbon tetrachloride, lead, etc.) can lead to cell injury or toxicity.
• The liver is particularly susceptible to chemical injuries due to its initial contact with ingested chemicals.

Types of Physical Injury

• Blunt Force Injuries: Result from mechanical force causing tissue tearing or crushing.
• Sharp Force Injuries: Can include incised, stab, and puncture wounds.
• Asphyxial Injuries: Occurs from failure of cells to receive or use oxygen, including strangulation or drowning.

Infectious Injury

• Microorganisms can invade and destroy tissues, produce toxins, and trigger hypersensitivity reactions.

Immunologic and Inflammatory Injury

• Results from immune system responses to infections and injuries, involving phagocytic cells and inflammatory substances.### Sources of Non-Functional Plasma Enzymes
• Increased synthesis of enzymes can occur, such as alkaline phosphatase in obstructive liver diseases due to bilirubin.
• Obstruction of bile ducts leads to elevated alkaline phosphatase levels.
• Increased cell membrane permeability, seen in tissue hypoxia, can result in higher enzyme levels.
• Cell damage, as in myocardial infarction or viral hepatitis, causes enzyme release into the bloodstream.

Medical Importance of Non-Functional Plasma Enzymes

• Measurement of plasma enzymes aids in diagnosing various diseases specific to different organs.
• Tracking plasma enzyme levels before and after treatment provides insights into disease prognosis.

Examples of Medically Important Non-Functional Plasma Enzymes

• Elevated amylase and lipase indicate diseases like acute pancreatitis.
• CK enzyme increases in heart, brain, and skeletal muscle disorders.
• Acid phosphatase rise is associated with prostate cancer.
• Alkaline phosphatase (ALP) increases in obstructive liver diseases, bone disorders, and hyperparathyroidism.
• Lactate dehydrogenase (LDH) increases in heart, liver, and hematological diseases.
• ALT, or serum glutamic pyruvic transaminase (SGPT), rises in liver and heart ailments.
• AST, known as serum glutamic oxaloacetic transaminase (SGOT), also increases in liver and heart diseases.

Overview of Cell Death

• Apoptosis and autophagy are regulated processes of programmed cell death.
• Necrosis, characterized by extensive damage and cellular swelling, is often passive but can also be programmed (necroptosis).

Types of Cell Death

• Apoptosis: Self-directed, controlled cell death involving caspases; eliminates worn-out or damaged cells.
• Autophagy: Degradation process that recycles unnecessary components through lysosomes; critical during stress (e.g., nutrient depletion).
• Necrosis: Unregulated destruction of cells leading to inflammation, loss of cell membrane integrity, and disruption of tissue regeneration.

Mechanisms and Key Points of Cell Injury

• Severe injury leads to necrosis and apoptosis; mild injury remains reversible.
• Injurious stimuli can induce cellular adaptations, like hypertrophy, hyperplasia, atrophy, and metaplasia.

Mutagens and Mutations

• Mutagens include agents like radiation and certain chemicals (e.g., nitrogen mustard).
• Mutations encompass inherited alterations, chromosome aberrations, single base pair substitutions, and frameshift mutations.
• Mutational hotspots are regions of chromosomes with higher mutation rates.

Single-Gene Disorders

• Autosomal Dominant Inheritance: Affected offspring typically arise from a heterozygous parent; each child has a 50% recurrence risk.
• Autosomal Recessive Inheritance: Affected individuals usually have two heterozygous carrier parents; recurrence risk is 25%.
• Epigenetics: Chemical modifications can alter gene expression without changing DNA sequence; genomic imprinting leads to inactivation of genes from one parent.

Epigenetics and Human Development

• Embryonic stem cells are totipotent, able to develop into all cell types.
• Specific genes express only in relevant cell types, aiding specialized functions.
• Epigenetic modifications play a crucial role in cellular diversification while housekeeping genes remain active across most cells.

Epigenetics and Cancer

• Tumor cells display hypomethylation; tumor-suppressor genes may become hypermethylated.
• MicroRNAs (miRNAs) regulate gene expression; when methylated, they can lead to overexpression of targeted mRNAs linked to metastasis.
• Epigenetic screening for cancer holds potential for early diagnosis, while pharmaceutical agents aim to reverse epigenetic changes associated with diseases.

Common Mechanisms in Cell Injury

• Mitochondrial damage leads to decreased ATP and increased reactive oxygen species (ROS).
• Calcium entry increases mitochondrial permeability and activates cellular enzymes.
• Membrane damage results in loss of cellular components and enzymatic digestion.
• Protein misfolding and DNA damage activate pro-apoptotic proteins, contributing to cell injury and death.

Test your understanding of physiology and its various levels, including molecular, organ, and systemic functions. This quiz also covers how living systems respond to physical activity and environmental factors, as well as the basics of disease pathophysiology. Challenge yourself to deepen your knowledge of the functions of life processes.