Chapter 1: The Human Body - An Orientation

Levels of Organization

The human body is organized in a hierarchical structure, from the simplest chemical level to the most complex organismal level.

• Atom: The smallest unit of matter; e.g., hydrogen, carbon.

• Molecule: Two or more atoms bonded together; e.g., water (H2O).

• Organelle: Specialized structures within cells; e.g., mitochondria.

• Cell: The basic unit of life; e.g., muscle cell.

• Tissue: Groups of similar cells performing a function; e.g., epithelial tissue.

• Organ: Structure composed of two or more tissue types; e.g., heart.

• Organ System: Group of organs working together; e.g., digestive system.

• Organism: The complete living being.

Example: The heart (organ) is made of muscle tissue, which consists of muscle cells containing mitochondria (organelles).

Organ Systems & Their Functions

Each organ system has a specific function essential for survival.

• Integumentary System: Protects the body, regulates temperature.

• Skeletal System: Provides support, protects organs, stores minerals.

• Muscular System: Enables movement, maintains posture.

• Nervous System: Controls responses, processes information.

• Endocrine System: Regulates hormones and metabolism.

• Cardiovascular System: Transports blood, nutrients, gases.

• Lymphatic System: Defends against infection, returns fluid to blood.

• Respiratory System: Exchanges gases (O2, CO2).

• Digestive System: Breaks down food, absorbs nutrients.

• Urinary System: Removes waste, regulates water balance.

• Reproductive System: Produces offspring.

Necessary Life Functions

Life functions are processes vital for survival.

• Maintaining boundaries (e.g., skin protects internal environment)

• Movement (muscle contraction, movement of substances)

• Responsiveness (ability to sense and respond to stimuli)

• Digestion (breakdown and absorption of nutrients)

• Metabolism (chemical reactions in the body)

• Excretion (removal of wastes)

• Reproduction (cellular and organismal reproduction)

• Growth (increase in size and number of cells)

Survival Needs

The body requires certain conditions to survive.

• Nutrients: For energy and cell building.

• Oxygen: Required for cellular respiration.

• Water: Essential for chemical reactions.

• Stable body temperature: For proper metabolic function.

• Atmospheric pressure: Necessary for gas exchange.

Homeostasis

Homeostasis is the maintenance of a stable internal environment.

• Feedback Mechanisms: Regulate homeostasis via three components:

  • Receptor: Detects changes (stimuli).

  • Control Center: Processes information and determines response.

  • Effector: Carries out the response.

• Information Flow: Afferent pathways carry information to the control center; efferent pathways carry commands to effectors.

• Negative Feedback: Reduces the effect of the stimulus (e.g., regulation of blood glucose).

• Positive Feedback: Enhances the effect of the stimulus (e.g., blood clotting).

Example: Thermoregulation: If body temperature rises, receptors signal the control center, which activates effectors (sweat glands) to cool the body.

Anatomical Terminology

Precise terminology is used to describe locations and directions in the body.

• Regional Terms: Refer to specific areas (e.g., brachial = arm).

• Directional Terms: Describe positions (e.g., superior, inferior, anterior, posterior).

• Body Cavities: Dorsal cavity (brain, spinal cord); ventral cavity (thoracic, abdominal, pelvic organs).

• Prefixes, Root Words, Suffixes: Used to construct anatomical terms (e.g., 'hypo-' = below, '-itis' = inflammation).

Example: The heart is located in the thoracic cavity, medial to the lungs.

Chapter 2: Basic Chemistry

Subatomic Particles of an Atom

Atoms are composed of three main subatomic particles:

• Protons: Positively charged, found in the nucleus.

• Neutrons: No charge, found in the nucleus.

• Electrons: Negatively charged, orbit the nucleus.

Atoms are the building blocks of matter; cells are the smallest units of life.

Chemical Bonding

Chemical bonds form molecules and compounds essential for life.

• Ionic Bonds: Formed by transfer of electrons; creates charged ions that attract each other.

• Covalent Bonds: Formed by sharing electrons; can be single, double, or triple bonds.

• Polar Covalent Bonds: Unequal sharing of electrons (e.g., water).

• Nonpolar Covalent Bonds: Equal sharing of electrons (e.g., O2).

• Hydrogen Bonds: Weak attractions between hydrogen and electronegative atoms (e.g., in water).

Example: Sodium (Na) and chlorine (Cl) form an ionic bond to create NaCl (table salt).

Polarity and Properties of Water

Water is a polar molecule, giving it unique properties vital for life.

• High heat capacity: Absorbs and releases heat slowly.

• Solvent properties: Dissolves many substances.

• Chemical reactivity: Participates in hydrolysis and dehydration reactions.

• Cohesion and adhesion: Water molecules stick to each other and to surfaces.

Importance: Water is essential for temperature regulation, transport, and chemical reactions in the body.

Inorganic Compounds

Inorganic compounds lack carbon and are vital for bodily functions.

• Water: Most abundant compound in the body.

• Salts: Electrolytes important for nerve and muscle function.

• Acids and Bases: Affect pH and metabolic processes.

pH Scale and Buffers

The pH scale measures hydrogen ion concentration in solutions.

• Scale: Ranges from 0 (acidic) to 14 (basic); 7 is neutral.

• Normal blood pH: 7.35–7.45.

• Acidosis: Blood pH below 7.35 (e.g., lactic acid from exercise).

• Alkalosis: Blood pH above 7.45 (e.g., loss of stomach acid from vomiting).

• Buffers: Chemicals that resist changes in pH; e.g., bicarbonate buffer system.

Buffer Equation:

Example: The bicarbonate buffer system maintains blood pH during exercise.

Molecule Formation and Breakdown

Molecules are formed and broken down by specific chemical reactions.

• Dehydration Synthesis: Forms new molecules by removing water.

• Hydrolysis: Breaks molecules by adding water.

Example: Formation of a disaccharide from two monosaccharides via dehydration synthesis.

Organic Compounds

Organic compounds contain carbon and are essential for life.

• Carbohydrates: Energy source; monomer = monosaccharide (e.g., glucose).

• Lipids: Energy storage, cell membranes; monomer = fatty acid/glycerol.

• Proteins: Structure, enzymes; monomer = amino acid.

• Nucleic Acids: Genetic information; monomer = nucleotide.

Levels of Protein Structure:

• Primary: Sequence of amino acids.

• Secondary: Alpha helix or beta sheet.

• Tertiary: 3D folding.

• Quaternary: Multiple polypeptides.

Denaturation: Loss of protein structure due to heat, pH, or chemicals.

Enzymes: Proteins that speed up chemical reactions; highly specific.

DNA: Contains instructions for protein synthesis.

Monomers and Polymers

Many organic compounds are polymers made from repeating monomers.

ATP: The Energy Molecule

ATP (adenosine triphosphate) stores and releases energy for cellular processes.

• Structure: Adenine, ribose, three phosphate groups.

• Energy Storage: Energy is stored in the bonds between phosphate groups.

• Phosphorylation: Addition of a phosphate group to a molecule, transferring energy.

ATP Hydrolysis Equation:

Example: Muscle contraction uses ATP for energy.

Additional info: Academic context was added to expand brief points and clarify concepts, including examples and equations.