Body structure & Function

Anatomy and Physiology

  • Anatomy: The study of the structure of an organism.

  • Physiology: The study of the function of an organism.

  • Pathophysiology: The study of diseases and disorders within the body.

  • Homeostasis: The body's systems working together to maintain a constant state of balance, ensuring all systems function cohesively.

Levels of Organization in the Human Body

  • The levels of organization, from simplest to most complex:

    • Atoms

    • Molecules

    • Organelles

    • Cells

    • Tissues

    • Organs

    • Organ Systems

    • Complete Organism

Atoms

  • Atoms are the basic unit of matter and consist of:

    • Protons: Positively charged particles.

    • Neutrons: Particles with no electrical charge.

    • Electrons: Negatively charged particles.

  • Protons and neutrons form the atomic nucleus, while electrons occupy orbitals around the nucleus.

  • There are 118 recognized elements in total.

Molecules

  • Molecules are formed by a chemical combination of two or more atoms to create specific chemical compounds.

  • States of matter for molecules: solid, liquid, or gas, based on how closely the molecules are packed together:

    • Gases: Molecules are farthest apart.

    • Liquids: Molecules are closer together but still mobile.

    • Solids: Molecules are tightly packed and move slowly.

Cells

  • Cells are the most basic unit of life and referred to as the building blocks of the human body, with millions of different types present.

  • Some organisms consist of a single cell, while others are multicellular.

  • Each cell has unique functions and characteristics, including:

    • Tissues: Bones, nerves, fat, reproductive cells, skeletal muscle, blood, and smooth muscle.

Cell Structure

  • Components of a cell include:

    • Cell Membrane: The outer covering maintaining cell shape, controlling the passage of substances in and out.

    • Cytoplasm: A jelly-like substance (approximately 80% water) that provides storage and workspace for the cell, resembling uncooked egg whites.

  • Organelles: Specialized structures within the cytoplasm, each performing specific tasks to maintain cell vitality. Key organelles include:

    • Endoplasmic reticulum

    • Ribosomes

    • Golgi apparatus

    • Mitochondria

    • Lysosomes

    • Centrioles

  • Nucleus: The control center of the cell, regulates metabolism, growth, and reproduction, and contains:

    • Nuclear membrane: Controls entry and exit of substances into the nucleus.

    • Chromosomes: Structures holding genes responsible for hereditary traits (23 pairs in humans).

DNA and RNA

  • DNA (Deoxyribonucleic Acid): Blueprint for genetic makeup, essential for cellular reproduction.

  • RNA (Ribonucleic Acid): A single chain of chemical bases that aids in gene expression and protein synthesis, includes:

    • Messenger RNA (mRNA)

    • Transfer RNA (tRNA)

  • Functions of RNA: storage and organization of genes, transport of genetic products, producing messages through RNA, production of ribosomes, uncoiling DNA for replication.

Cell Division

  • Mitosis: Process where a single cell divides, resulting in two identical nuclei. Consists of five stages:

    • Prophase

    • Prometaphase

    • Metaphase

    • Anaphase

    • Telophase

  • Following mitosis, Cytokinesis occurs, dividing the cytoplasm, organelles, and membrane into two daughter cells.

  • Post-division, each new cell maintains 23 pairs of chromosomes (total of 46).

  • Meiosis: Cellular division in reproductive cells; yields gametes:

    • In males: Sperm cells.

    • In females: Ova (eggs).

  • A fertilized gamete results in a zygote, the earliest stage of an embryo.

Tissues in the Human Body

  • Specialized cells with the same function & purpose , group together to form Tissues.

  • Different types of tissues formed by specialized cell grouping, four primary types:

    • Epithelial Tissue:

    • Found on skin's outer layer, covering organ surfaces, lining cavities.

    • Functions: absorption, secretion, excretion, protection.

    • Appearance: Sheet-like, can be several layers thick.

    • Connective Tissue:

    • The most abundant tissue type, with liquid or gel-like consistency.

    • Functions: support for organs, muscle coverage, and connections between muscles, bones, and joints.

    • Includes Blood & Lymph

    • Muscle Tissue:

    • Voluntary, Striated Muscle: Skeletal muscle, controlled consciously.

    • Involuntary Smooth Muscle: Not under conscious control, regulated by the autonomic nervous system.

    • Cardiac Muscle: Striated muscle forming the heart, also controlled by the autonomic nervous system.

    • Nerve Tissue:

    • Composed of neurons (nerve cells), essential for conducting impulses in the nervous system.

    • Properties: Excitability (ability to transmit impulses) and Conductivity (ability to conduct impulses).

Body Organs and Systems

  • Groups of similar functioning tissues create organs, which work together to form body systems.

  • Body systems cooperate to maintain homeostasis in the human body.

Chemistry in Cellular Functions

  • Cells receive nourishment and eliminate waste through various transport mechanisms:

    • Passive Transport: Does not require energy; includes:

    • Diffusion

    • Osmosis

    • Filtration

    • Active Transport: Requires energy, allows cells to acquire necessary materials against concentration gradients.

Importance of Electrolyte Balance

  • Electrolytes: Molecules that conduct electricity when dissolved in bodily fluids, existing as cations (positively charged) or anions (negatively charged).

  • Functions of electrolytes include maintaining voltage across cell membranes.

  • Kidneys play a crucial role in regulating electrolyte concentrations in blood, ensuring balance despite bodily changes.

  • Key electrolytes: Sodium chloride, sodium, potassium, chloride, calcium, magnesium, bicarbonate, phosphate, and sulfate.

Metabolism

  • Refers to all chemical processes necessary for maintaining life, including energy production and release.

  • Energy is required for:

    • Replenishing cells

    • Damage repair

    • Environmental adaptation

  • Anabolism: The process of building up, creating larger molecules from smaller ones (e.g., synthesis of proteins).

  • Catabolism: The breaking down of larger units into smaller ones (e.g., digestion).