Common Functions of Living Things

Overview of Life Functions

All living organisms share several essential functions that sustain life and ensure survival. These functions are foundational to the study of anatomy and physiology.

• Responsiveness/Irritability: The ability to detect and respond to changes in the environment. Example: Withdrawal from a painful stimulus.

• Adaptability: Capacity for longer-term adjustments to environmental changes.

• Growth: Increase in cell number and size; includes cellular differentiation (cells becoming specialized).

• Reproduction: Production of new generations of the same type of organism.

• Movement: Internal (transporting substances within the body) and external (moving through the environment).

• Metabolism: Sum of all chemical operations in the body, including:

  • Respiration: Absorption, transport, and use of oxygen by cells.

  • Digestion: Breakdown of complex foods into simpler compounds for absorption.

  • Excretion: Elimination of waste products generated by metabolic operations.

Types of Anatomy & Physiology

Anatomy: Study of Structure

Anatomy focuses on the internal and external structures of the body and the physical relationships between body parts.

• Gross/Macroscopic Anatomy: Structures visible without a microscope.

  • Surface Anatomy: General form and superficial markings.

  • Regional Anatomy: Specific regions of the body.

  • Systemic Anatomy: Major organ systems.

• Microscopic Anatomy: Structures requiring magnification.

  • Cytology: Study of individual cells.

  • Histology: Study of tissues.

Physiology: Study of Function

Physiology examines how living organisms perform their vital functions.

• Cell Physiology: Functions of living cells.

• Special Physiology: Functions of specific organs.

• Systemic Physiology: Functions of organ systems.

• Pathological Physiology: Effects of diseases on organ or system functions.

Levels of Organization

Hierarchical Structure

The human body is organized into increasingly complex levels:

• Atoms → Molecules → Cells → Tissues → Organs → Organ Systems → Organism

Organ Systems of the Human Body

Major Organ Systems and Their Functions

There are eleven major organ systems, each with specific roles in maintaining homeostasis.

• Integumentary: Protection, body temperature regulation, sensory information (skin, hair, nails).

• Skeletal: Support, mineral storage, blood cell formation (bones).

• Muscular: Movement, heat production.

• Nervous: Immediate response to stimuli (brain, spinal cord, nerves).

• Endocrine: Long-term changes via hormones (pituitary, thyroid, adrenal glands).

• Cardiovascular: Transport of cells, nutrients, wastes (heart, blood vessels).

• Lymphatic: Defense against infection (spleen, thymus, lymph nodes).

• Respiratory: Gas exchange (nasal cavity, trachea, bronchi, lungs).

• Digestive: Absorption of nutrients (mouth, pharynx, esophagus, stomach, intestines).

• Urinary: Elimination of waste products (kidneys, ureters, bladder, urethra).

• Reproductive: Production of gametes (sperm and eggs).

Homeostasis

Maintaining Internal Balance

Homeostasis is the state of internal balance required for proper function.

• Homeostatic Regulation:

  1. Receptor: Senses a particular change or stimulus.

  2. Control/Integration Center: Receives and processes information.

  3. Effector: Responds to the control center's commands.

• Negative Feedback: Response corrects the situation back to normal range. Example: Thermoregulation (sweating, shivering).

• Positive Feedback: Response reinforces or exaggerates the original stimulus. Example: Childbirth, blood clotting.

Anatomical Position and Directions

Standard Reference Position

The anatomical position is used as a reference for describing locations and directions on the body.

• Standing upright, hands at the sides, palms facing forward, feet together.

• Supine: Face up

• Prone: Face down

Directional Terms

• Anterior/Ventral: Front of the body

• Posterior/Dorsal: Back of the body

• Medial: Closer to the midline

• Lateral: Away from the midline

• Proximal: Closer to the trunk

• Distal: Farther from the trunk

• Superior/Cranial: Towards the head

• Inferior/Caudal: Towards the feet

• Superficial: Closer to the surface

• Deep: Far from the surface

Sectional Planes

• Frontal/Coronal Plane: Divides body into anterior and posterior portions

• Sagittal Plane: Divides body into left and right portions (midsagittal = equal halves)

• Transverse Plane: Divides body into superior and inferior portions

Body Cavities

Major Body Cavities and Membranes

Body cavities protect internal organs, allow organs to change shape, and are lined by serous membranes.

• Thoracic Cavity:

  • Pericardial cavity (heart):

    • Visceral pericardium: layer covering the heart

    • Parietal pericardium: outer layer

  • Pleural cavities (lungs):

    • Visceral pleura: covers lung surface

    • Parietal pleura: lines cavity edge

  Separated by the diaphragm

• Abdominopelvic Cavity:

  • Abdominal cavity (superior portion)

  • Pelvic cavity (inferior portion)

  • Peritoneal cavity:

    • Visceral peritoneum: covers enclosed organs

    • Parietal peritoneum: lines inner surface of body wall

Basic Chemistry for Anatomy & Physiology

Introduction to Chemistry

Chemistry is the science that investigates matter and its interactions, which is essential for understanding physiological processes.

• Matter: Anything that takes up space and has mass; composed of atoms.

• Mass: Amount of matter an object contains.

Atomic Structure

• Subatomic Particles:

  • Protons (p+): Positive charge

  • Neutrons (n or n0): Neutral charge

  • Electrons (e-): Negative charge

• Atomic Number: Number of protons in an atom.

• Isotopes: Atoms of the same element with different numbers of neutrons.

• Radioisotopes: Unstable isotopes that spontaneously emit subatomic particles.

• Atomic Mass: Total number of protons and neutrons in the nucleus.

• Atomic Weight: Average mass of all isotopes.

Electron Shells and Chemical Bonds

• Electrons orbit the nucleus in shells; only electrons in the outer shell interact with other atoms.

• First shell holds up to 2 electrons; second shell up to 8 electrons.

• Atoms with filled outer shells are stable.

• Chemical Bond: Atoms together after a reaction has ended.

• Molecule: Two or more atoms bonded together by shared electrons.

• Compound: Molecule made of atoms of two or more different elements in a fixed proportion (e.g., H2O, C6H12O6).

Ions and Types of Chemical Bonds

• Ions: Atoms or molecules with an electric charge due to unequal numbers of protons and electrons.

  • Cations: Positive charge (atom loses electrons)

  • Anions: Negative charge (atom gains electrons)

• Ionic Bond: Created by electrical attraction between cations and anions.

• Covalent Bond: Formed by sharing electrons between atoms (very strong).

  • Nonpolar Covalent: Electrons shared equally.

  • Polar Covalent: Electrons shared unequally, creating partial charges (e.g., water molecule).

• Hydrogen Bond: Weak attraction between a slight positive charge on a hydrogen atom and a slight negative charge on another atom (e.g., between water molecules).

Surface Tension

• Attraction between water molecules creates surface tension, allowing water to resist external force and pull molecules closer together.

Energy and Chemical Reactions

Types of Energy

• Kinetic Energy: Energy of motion.

• Potential Energy: Stored energy.

Decomposition and Synthesis Reactions

• Decomposition: Breaking down molecules into smaller parts.

  • Hydrolysis: Water decomposition.

  • Catabolism: Complex molecules broken down; releases kinetic energy.

• Synthesis: Assembling larger molecules from smaller parts.

  • Anabolism: New compounds in the body; requires energy.

  • Dehydration/Condensation: Removal of water to form bonds.

• Exchange Reactions: Shuffle parts of reacting molecules.

  • General equation:

Enzymes and Activation Energy

• Activation Energy: Amount of energy required to start a reaction. Example: Enzymes lower activation energy, allowing reactions to occur at body temperature.

• Catalysts: Accelerate reactions without permanent change.

Exergonic and Endergonic Reactions

• Exergonic: Release energy; amount released is greater than activation energy. Example: Most common in the body; generate heat to maintain body temperature.

• Endergonic: Absorb energy; more energy needed to begin than is released.

Nutrients, Metabolites, and Compounds

Nutrients and Metabolites

• Nutrients: Substances from food necessary for normal physiological functions (carbohydrates, proteins, fats, vitamins, minerals, water).

• Metabolites: Substances involved in or produced by metabolism.

Inorganic vs. Organic Compounds

• Inorganic Compounds: Usually do not contain both carbon and hydrogen; include water, CO2, oxygen, acids, bases, salts.

• Organic Compounds: Contain carbon covalently bonded with one or more other elements; must have a C-H covalent bond; larger and more complex molecules.

Properties of Water

Role of Water in the Body

• Essential reactant in chemical reactions.

• Most chemical reactions in the body occur in aqueous solutions.

• Dissociation/Ionization: Ionic compounds separate into charged ions in water.

• Electrolytes: Substances that release ions in water and conduct electricity.

Acids, Bases, and pH

• Acid: Substance that releases hydrogen ions (H+); proton donor.

• Base: Substance that removes hydrogen ions; proton acceptor.

• pH: Measure of hydrogen ion concentration; blood and most body fluids are maintained at pH 7.35–7.45.

• Buffer: Compound that stabilizes pH by removing or replacing H+.

Major Organic Molecules

Carbohydrates

Organic compounds with carbon, hydrogen, and oxygen; primary energy source.

• Monosaccharides: Simple sugars (e.g., glucose).

• Disaccharides: Two monosaccharides joined by covalent bonds (e.g., sucrose).

• Polysaccharides: Many monosaccharides linked by covalent bonds (e.g., glycogen).

Lipids

Contain carbon-to-hydrogen ratio of 1:2; include fats, oils, and waxes; essential for cell structure and energy storage.

• Fatty Acids: Long chains of carbon with attached hydrogen and a carboxyl group (COOH).

• Saturated: No double bonds between carbon atoms.

• Unsaturated: One or more double bonds; can be monounsaturated or polyunsaturated.

• Steroids: Large lipid molecules with four connected carbon rings.

Proteins

Composed of carbon, hydrogen, oxygen, and nitrogen; account for 20% of body weight; diverse functions.

• Support: Structural proteins create framework.

• Movement: Contractile proteins for muscle contraction.

• Transport: Carrier proteins move substances in blood.

• Buffering: Help maintain pH.

• Metabolic Regulation: Enzymes for chemical reactions.

• Coordination and Control: Hormones regulate activities.

• Defense: Antibodies protect against disease.

Nucleic Acids

Store and transfer information for protein synthesis; include DNA and RNA.

• DNA: Contains deoxyribose, phosphate group, and nitrogenous bases (adenine, guanine, cytosine, thymine).

• RNA: Contains ribose, phosphate group, and nitrogenous bases (adenine, guanine, cytosine, uracil).

ATP (Adenosine Triphosphate)

ATP is the primary energy carrier in cells; energy is released when high-energy bonds are broken.

• Structure: Adenosine monophosphate joined to two phosphate groups by high-energy bonds.

• Function: Provides energy for metabolic reactions.

• Equation: