ANP Study Guide: The Human Body, Chemistry of Life, and Cells

Chapter 1: The Human Body – An Orientation

Anatomy Definitions

Anatomy is the study of the structure of body parts and their relationships to one another. It is divided into several branches:

• Gross Anatomy (Macroscopic Anatomy): Study of large, visible body structures.

• Microscopic Anatomy: Study of structures too small to be seen with the naked eye.

• Developmental Anatomy: Study of anatomical and physiological development throughout life.

Six Levels of Structural Organization

The human body is organized into six increasingly complex levels:

1. Chemical Level: Atoms combine to form molecules, which form organelles (specialized structures within cells).

2. Cellular Level: Cells are made of molecules and are the smallest units of living things. They vary in shape and size according to function.

3. Tissue Level: Tissues are groups of similar cells with a common function. The four basic tissue types are:

   • Epithelial: Covers body surfaces and lines cavities.

   • Muscle: Provides movement.

   • Connective: Supports and protects the body.

   • Nervous: Enables rapid internal communication via electrical impulses.

   Mnemonic: "Every One Can Make Noise"

4. Organ Level: Organs are composed of two or more tissue types working together for specific functions.

5. Organ System Level: Organs work together to accomplish a common purpose.

6. Organismal Level: All structural levels work together to keep the organism alive.

Eleven Organ Systems & Major Functions

The body has eleven organ systems, each with specific functions. Mnemonic: "MURDERS LINC"

• Muscular System: Movement, posture, heat production.

• Urinary System: Excretion of wastes, regulation of water and electrolytes.

• Respiratory System: Gas exchange (oxygen and carbon dioxide).

• Digestive System: Breakdown and absorption of nutrients.

• Endocrine System: Regulation via hormone secretion.

• Reproductive System: Production of gametes and hormones; supports fertilization and development.

• Skeletal System: Support, protection, movement, blood cell formation, mineral storage.

• Lymphatic System: Fluid balance, immune response.

• Integumentary System: Protection, vitamin D synthesis, sensory reception.

• Nervous System: Fast-acting control and communication.

• Cardiovascular System: Transport of substances via blood.

Homeostasis

Homeostasis is the body's ability to maintain stable internal conditions despite external changes. It is a dynamic equilibrium maintained by all organ systems.

• Examples: Body temperature, blood glucose, water balance, blood pressure, pH, calcium levels.

Components of homeostatic control:

• Receptor: Detects changes and sends signals (afferent pathway).

• Control Center: Processes information and determines response.

• Effector: Carries out the response (muscle or gland).

Negative Feedback: Most common mechanism; response reduces or shuts off original stimulus (e.g., temperature regulation, blood glucose control).

Anatomical Position and Directional Terms

• Anatomical Position: Body erect, feet slightly apart, palms forward, thumbs away from body.

• Directional Terms:

  • Superior (Cranial): Toward the head.

  • Inferior (Caudal): Away from the head.

  • Anterior (Ventral): Toward the front.

  • Posterior (Dorsal): Toward the back.

  • Medial: Toward the midline.

  • Lateral: Away from the midline.

  • Intermediate: Between medial and lateral.

  • Proximal: Closer to point of attachment.

  • Distal: Farther from point of attachment.

  • Superficial (External): Toward body surface.

  • Deep (Internal): Away from body surface.

Regional Terms and Body Cavities

• Axial Region: Head, neck, trunk.

• Appendicular Region: Limbs/appendages.

• Body Cavities:

  • Cranial: Contains brain.

  • Vertebral: Contains spinal cord.

  • Thoracic: Contains lungs and heart.

  • Abdominal: Contains digestive organs.

  • Pelvic: Contains bladder, reproductive organs, rectum.

Body Planes and Sections

• Sagittal: Divides body into right and left parts.

• Frontal (Coronal): Divides body into anterior and posterior parts.

• Transverse: Divides body into superior and inferior parts.

• Oblique: Diagonal cut.

Abdominopelvic Quadrants

• Right Upper Quadrant (RUQ)

• Left Upper Quadrant (LUQ)

• Right Lower Quadrant (RLQ)

• Left Lower Quadrant (LLQ)

Chapter 2: Chemistry Comes Alive

Biochemistry and Compounds

Biochemistry is the study of the chemical composition and reactions of living matter. Compounds are classified as:

• Inorganic Compounds: Usually do not contain carbon (e.g., water, salts, acids, bases).

• Organic Compounds: Contain carbon, usually large and covalently bonded (e.g., carbohydrates, lipids, proteins, nucleic acids).

• Exceptions: CO2 and CO are inorganic despite containing carbon.

Water

• Most abundant inorganic compound (60–80% of cell volume).

• Universal solvent due to polarity.

• Major transport medium in the body.

Salts & Electrolytes

• Salts dissociate into ions (cations and anions) in water.

• Electrolytes: Ions that conduct electrical currents in solution; essential for brain, heart, and muscle function.

• Important Electrolytes: Sodium, potassium, calcium, iron.

Acids & Bases

• Acids: Proton donors; release H+ in solution (e.g., $\mathrm{HCl} \rightarrow \mathrm{H}^+ + \mathrm{Cl}^-$ ).

• Bases: Proton acceptors; take up H+ or release OH- (e.g., $\mathrm{NaOH} \rightarrow \mathrm{Na}^+ + \mathrm{OH}^-$ ).

• pH: Measures H+ concentration; neutral solution has pH = 7.

• Buffers: Prevent dramatic pH changes, maintaining acid-base balance.

Macromolecules (Organic Compounds)

Carbohydrates

• Monomers: Monosaccharides (e.g., glucose).

• Polymers: Polysaccharides (e.g., glycogen).

• Types: Monosaccharides, disaccharides, polysaccharides.

• Functions: Major source of cellular fuel, energy storage, structural support, cell communication.

• Composition: Carbon, hydrogen, oxygen.

Lipids

• Insoluble in water.

• Triglycerides: 3 fatty acids + glycerol; function in energy storage, insulation, protection.

• Saturated Fats: No double bonds; straight chains.

• Unsaturated Fats: One or more double bonds; bent chains.

• Phospholipids: Glycerol + 2 fatty acids + phosphate group; major component of cell membranes (polar head, nonpolar tail).

• Steroids: Four interlocking rings (e.g., cholesterol, vitamin D, steroid hormones, bile salts).

Proteins

• 20–30% of cell weight.

• Functions: Structural support, enzymes, muscle contraction, transport.

• Monomers: Amino acids, linked by peptide bonds.

Nucleic Acids

• Monomers: Nucleotides (nitrogen base, pentose sugar, phosphate group).

• Types: DNA (double helix, genetic blueprint, in nucleus), RNA (single-stranded, protein synthesis, outside nucleus).

• Base Pairing: DNA: A–T, G–C; RNA: A–U, C–G.

• Types of RNA: mRNA, tRNA, rRNA.

ATP (Adenosine Triphosphate)

• Cell's "energy currency."

• Provides immediate usable energy for cells.

• ATP cycle: Food → glucose → ATP; ATP hydrolysis releases energy ($\mathrm{ATP} \rightarrow \mathrm{ADP} + \mathrm{P}_i$).

Chapter 3: Cells – The Living Units

Cell Theory

• Cells are the smallest unit of life.

• All organisms are made of one or more cells.

• Cells arise only from other cells.

Three Basic Parts of the Cell

• Plasma Membrane: Outer boundary; selectively permeable.

• Cytoplasm: Intracellular fluid with organelles.

• Nucleus: Control center; contains DNA.

Extracellular Materials

• Interstitial Fluid: Bathes cells.

• Blood Plasma: Fluid portion of blood.

• Cerebrospinal Fluid: Surrounds nervous system organs.

• Cellular Secretions: Saliva, mucus, etc.

• Extracellular Matrix: Glue-like substance holding cells together.

Plasma Membrane Structure & Function

• Phospholipid bilayer with cholesterol and proteins.

• Integral Proteins: Embedded; function as channels, carriers, enzymes, receptors.

• Peripheral Proteins: Loosely attached to membrane surface.

Cell Junctions

• Tight Junctions: Impermeable seals between cells.

• Desmosomes: Anchoring junctions; provide mechanical strength.

• Gap Junctions: Allow ions and small molecules to pass; important in heart and embryonic cells.

Membrane Transport

• Passive Transport: No ATP; moves substances down concentration gradient.

  • Simple Diffusion: Nonpolar/lipid-soluble substances (e.g., O2, CO2).

  • Facilitated Diffusion: Uses carriers/channels (e.g., glucose, amino acids, ions).

  • Osmosis: Diffusion of water via aquaporins.

• Active Transport: Requires ATP; moves substances against gradient.

• Vesicular Transport: Uses vesicles; includes endocytosis (phagocytosis, pinocytosis, receptor-mediated) and exocytosis.

Osmolarity & Tonicity

• Osmolarity: Total concentration of solute particles.

• Tonicity: Ability of a solution to change cell shape/volume.

• Isotonic: No net water movement; cell size unchanged.

• Hypertonic: Water leaves cell; cell shrinks.

• Hypotonic: Water enters cell; cell swells and may lyse.

Cytoplasm & Organelles

• Cytosol: Gel-like solution with water and solutes.

• Inclusions: Insoluble molecules (e.g., glycogen, pigments, lipid droplets).

• Organelles:

  • Membranous: Mitochondria (ATP synthesis), rough ER (protein synthesis), smooth ER (lipid/steroid synthesis, detox), Golgi apparatus (modifies/packages proteins), lysosomes (digestion).

  • Non-membranous: Ribosomes, cytoskeleton, centrioles.

• Cytoskeleton: Microfilaments (movement), intermediate filaments (support), microtubules (shape, transport, cilia/flagella).

• Centrioles: Organize spindle during mitosis; form cilia/flagella bases.

• Nucleolus: Site of ribosome subunit production.

Cell Cycle

• Interphase: Cell growth and normal activity.

  • G1: Growth and metabolism.

  • S: DNA replication.

  • G2: Preparation for division.

  • G0: Nondividing state.

• Mitotic Phase: Cell division (mitosis and cytokinesis).

Mitosis Stages

• Prophase: Chromatin condenses, nuclear envelope breaks down, spindle forms.

• Metaphase: Chromosomes align at metaphase plate.

• Anaphase: Sister chromatids separate to opposite poles.

• Telophase: Chromosomes uncoil, nuclear membranes reform.

• Cytokinesis: Cytoplasm divides, producing two daughter cells.

Cell Cycle Regulation

• Go Signals: Growth factors, hormones, inadequate membrane surface area.

• Stop Signals: Contact inhibition.

DNA Replication

• DNA Polymerase: Enzyme that builds new DNA strands.

• Semiconservative Replication: Each new DNA molecule has one original and one new strand.

Protein Synthesis

• Gene: Segment of DNA coding for a protein.

• Codon: Three-base sequence coding for an amino acid.

• Role of RNA:

  • mRNA: Carries DNA instructions to ribosome.

  • rRNA: Forms ribosomes.

  • tRNA: Carries amino acids to ribosome.

• Transcription: DNA information copied into mRNA (in nucleus).

• Translation: mRNA decoded to build proteins (at ribosomes in cytoplasm).

• Amino Acids: Building blocks of proteins, joined by peptide bonds.