Physiology and Blood Study Notes

INTRODUCTION TO PHYSIOLOGY AND BLOOD

  • Human physiology studies biological function, focusing on cause-and-effect mechanisms.

  • Knowledge derived from experimental evidence and scientific methods.

  • Pathophysiology explores alterations in physiological processes due to disease/injury.

  • Comparative physiology enhances understanding of human physiology through invertebrate and vertebrate studies.

BRIEF HISTORY OF PHYSIOLOGY

  • Aristotle speculated human function; Erasistratus (father of physiology), Galen (authority until Renaissance).

  • William Harvey: Demonstrated heart’s function in blood circulation.

  • Claude Bernard: Concept of milieu interieur (homeostasis).

  • Walter Cannon: Coined "homeostasis"; mechanisms regulate internal constancy.

HOMEOSTASIS

  • Refers to relative constancy of the internal environment.

  • Important for understanding physiology, fundamental for medical diagnostics.

  • Negative feedback mechanisms maintain homeostasis through sensors and integrating centers (e.g., brain regions).

FEEDBACK MECHANISMS

  • Negative Feedback: Reverses deviations from set points (e.g., body temperature, glucose levels).

  • Positive Feedback: Amplifies changes (e.g., blood clotting, childbirth).

BODY-FLUID COMPARTMENTS

  • Divided into Intracellular Fluid Compartment (ICF) and Extracellular Fluid Compartment (ECF).

  • ECF includes blood plasma and tissue fluid (interstitial fluid).

CELL STRUCTURE AND FUNCTIONS

  • Basic unit of structure and function; cells house organelles performing specific tasks.

  • Three main parts of a cell: Plasma membrane, Cytoplasm with organelles, Nucleus containing DNA.

PLASMA MEMBRANE

  • Composed of phospholipids and proteins, allowing selective permeability.

  • Membrane proteins are integral (span membrane) or peripheral (partially embedded).

CYTOPLASM & ORGANELLES

  • Contains organelles like lysosomes (digestion), mitochondria (energy production), and ribosomes (protein synthesis).

  • Cytoskeleton provides structural support.

BLOOD FUNCTIONS

  • Main roles: transportation (O2, nutrients), regulation (hormones, temperature), protection (clotting, immune response).

BLOOD COMPOSITION

  • Comprises plasma (liquid) and formed elements: erythrocytes (RBCs), leukocytes (WBCs), and platelets.

  • Normal hemoglobin levels are crucial for oxygen transport.

ANEMIA

  • Below-normal O2-carrying capacity; can result from nutritional deficits, bone marrow suppression, or excessive blood loss.

  • Types include nutritional anemia, aplastic anemia, and sickle cell anemia.

POLYCYTHEMIA

  • Increase in RBC mass; causes include primary (genetic) and secondary (hypoxia-related) polycythemia.

IMMUNE SYSTEM

  • Divided into innate (nonspecific) and adaptive (specific) immunity.

  • Leukocytes play major roles in protection and inflammation processes.

PHAGOCYTIC CELLS

  • Include neutrophils and macrophages; engulf pathogens and debris.

ANTIBODIES & COMPLEMENT SYSTEM

  • Antibodies target specific antigens, aiding in pathogen destruction.

  • Complement proteins enhance immune response through opsonization and cytolysis.

CLONAL SELECTION

  • B cells and T cells respond specifically to antigens; memory cells provide long-term immunity.

VACCINATION

  • Induces active immunity by exposing the immune system to non-virulent forms of pathogens or their components.

PASSIVE IMMUNITY

  • Transfers antibodies from donor to recipient (e.g., maternal to fetus); does not involve the recipient's immune response.

PATHOPHYSIOLOGY TOPICS

  • Anemia: Various causes; affects oxygen delivery.

  • Leukemia and lymphoma: Malignant proliferation of blood cells.

  • HIV/AIDS: Depletes immune function by targeting CD4+ T cells.


Human physiology studies biological function, focusing on cause-and-effect mechanisms. The knowledge is derived from experimental evidence and scientific methods. Pathophysiology explores alterations in physiological processes due to disease or injury, while comparative physiology enhances understanding of human physiology through studies of invertebrates and vertebrates.

A brief history of physiology includes speculations by Aristotle about human function. Erasistratus is considered the father of physiology, with Galen serving as an authority until the Renaissance. William Harvey demonstrated the heart's function in blood circulation, followed by Claude Bernard, who introduced the concept of milieu intérieur, or homeostasis. Walter Cannon later coined the term "homeostasis," which refers to mechanisms that regulate internal constancy.

Homeostasis signifies the relative constancy of the internal environment, which is pivotal for understanding physiology and fundamental for medical diagnostics. Negative feedback mechanisms maintain homeostasis through sensors and integrating centers, such as brain regions. Feedback mechanisms themselves can be classified into negative feedback, which reverses deviations from set points (such as body temperature and glucose levels), and positive feedback, which amplifies changes (as seen in blood clotting and childbirth).

The body’s fluid compartments are divided into the Intracellular Fluid Compartment (ICF) and the Extracellular Fluid Compartment (ECF), with the latter including blood plasma and interstitial fluid. The basic unit of structure and function in the body is the cell, which houses organelles that perform specific tasks. Each cell consists of three main parts: the plasma membrane, the cytoplasm containing organelles, and the nucleus that houses DNA.

The plasma membrane is composed of phospholipids and proteins, allowing selective permeability. Membrane proteins are classified as integral (spanning the membrane) or peripheral (partially embedded). The cytoplasm includes various organelles such as lysosomes for digestion, mitochondria for energy production, and ribosomes for protein synthesis. The cytoskeleton provides structural support within the cell.

Blood serves several vital functions, primarily transportation (for oxygen and nutrients), regulation (of hormones and temperature), and protection (through clotting and immune response). The composition of blood includes plasma (the liquid component) and formed elements such as erythrocytes (RBCs), leukocytes (WBCs), and platelets. Normal hemoglobin levels are crucial for effective oxygen transport.