Introduction to Physiology

Introduction to Physiology

  • Definition: An investigation of the processes or functions of living organisms (Seeley’s Anatomy and Physiology, 13th Ed).

  • Importance of Physiology: Provides an in-depth understanding of the human body and its functions.

Levels of Organization in the Human Body

  1. Chemical Level: Involves atoms and molecules.

  2. Cell Level: Cellular units containing organelles ("little organs") that perform essential functions.

  3. Tissue Level: Composed of groups of similar cells.

    • Types of Tissues:

      • Epithelial

      • Connective

      • Muscle

      • Nervous

  4. Organ Level: Comprises two or more types of tissues.

  5. Organ System Level: Consists of multiple organs working together for a common purpose.

    • 11 Organ Systems (to be detailed).

  6. Organism Level: Represents a whole living entity.

Characteristics of Life

  • Organization: Interaction of all levels of organization for function.

  • Metabolism: Chemical reactions essential for maintaining life; includes energy utilization.

  • Responsiveness: Ability to detect and respond to internal and external changes (controlled by Nervous and Endocrine systems).

  • Reproduction: Processes involved in cell creation.

  • Development: Changes from fertilization to death, including differentiation from immature to specialized states.

  • Growth: Increase in cell size and/or number.

Cell Biologyn

Plasma Membrane

  • Functions:

    1. Barrier: Separates intracellular fluid from extracellular fluid.

    2. Encloses cell contents.

    3. Connects cells to their external environment.

    4. Facilitates communication.

    5. Regulates movement of substances in and out of the cell.

Plasma Membrane Components

  • Membrane Lipids: Phospholipids form a lipid bilayer, cholesterol embedded within.

  • Membrane Proteins:

    • Integral proteins (embedded in the membrane)

    • Peripheral proteins (attached to the surface).

Types of Movement across Plasma Membrane

  1. Passive Transport:

    • Diffusion: Movement of solutes from high to low concentration.

    • Osmosis: Water movement to equilibrate solute concentrations.

    • Facilitated Diffusion: Movement aided by proteins.

  2. Active Transport:

    • Active Transport: Energy use to move substances against a concentration gradient (e.g., Sodium-potassium pump).

    • Secondary Active Transport: Indirect use of energy.

    • Vesicular Transport: Involves vesicles to transport substances, classified into:

      • Endocytosis: Phagocytosis (cell-eating) and Pinocytosis (cell-drinking).

      • Exocytosis: Release of materials from the cell.

Cytoplasm

  • Composed of Cytosol and Organelles.

    • Cytosol: Suspended and dissolved molecules.

    • Cytoskeleton: Provides support and maintains organelle positioning.

Nucleus

  • Contains nucleoplasm, nuclear envelope, nuclear pores, chromosomes, DNA, RNA, and ribosomes.

    • Ribosomes: Sites of protein synthesis that produce proteins for use inside the cell and for secretion.

Endoplasmic Reticulum (ER)

  • Continuation of the nuclear envelope.

    • Rough ER: Ribosomes on its surface; involved in protein synthesis.

    • Smooth ER: No ribosomes; synthesizes lipids, detoxifies substances.

Golgi Apparatus

  • Membranous sacs that modify, package, and distribute molecules produced by the endoplasmic reticulum.

Mitochondria

  • Responsible for ATP production, considered the cells' energy factories.

    • Involved in the Citric Acid cycle and Electron Transport chain.

    • Can increase in number based on cellular energy demands.