Introduction to Biological Molecules, Reactions, and Cellular Energy Flashcards

Anatomical Terminology, Directional Positions, and Body Planes

• Directional terms are best mastered as functional pairs of opposites. Learning these terms in pairs establishes clear spatial relationships across anatomical structures.

Directional Term Pairs

• Superior vs. Inferior:

  • Superior: Pertains to above or an upper portion of a structure.

  • Inferior: Pertains to below or a lower portion of a structure.

• Cranial, Cephalic, Encephalos, and Caudal:

  • Cephalic: Defined specifically as pertaining to the head.

  • Cranial: Defined specifically as pertaining to the cranium (skull).

  • Encephalos: Refers specifically to the brain.

  • Caudal: Defined as pertaining to the tail, which is the direct opposite of the head.

• Anterior vs. Posterior:

  • Anterior: Pertains to the front of the body.

  • Posterior: Pertains to the back of the body.

• Ventral vs. Dorsal:

  • Ventral: In healthcare practice, reserved specifically to describe structures or cavities located at the front of the body.

  • Dorsal: Reserved specifically to describe structures or cavities located at the posterior or back portion of the body.

• External vs. Internal:

  • External: Refers to the outside (e.g., external bleeding where blood flows outside the body).

  • Internal: Refers to the inside (e.g., internal bleeding contained inside the body).

• Superficial vs. Deep:

  • Superficial: Located on or near the physical surface.

  • Deep: Extends far down into the interior of the body.

• Central vs. Peripheral:

  • Central: Located at or near the center of a structure or body part.

  • Peripheral: Located on the outer boundary or outside (e.g., the periosteum on the outside of a bone, or Interstate 575 acting as a perimeter loop).

• Proximal vs. Distal:

  • These terms define a relative relationship along a pathway and must always be stated relative to a specific reference point or point of origin.

  • Proximal: Nearest to the point of origin or showing up first along a functional pathway.

  • Distal: Furthest away from the point of origin along a functional pathway.

  • Crucial Rule: Proximal and distal are distinct terms and must never be used interchangeably with superior and inferior.

Demonstrations of Proximal and Distal Relationships

• Small Intestine Pathway:

  • Originates after the stomach and consists of three continuous sections in order: the duodenum (first section), the jejunum (middle section), and the ileum (final section).

  • A pathology located in the duodenum or jejunum is in the proximal portion of the small intestine (closest to the point of origin).

  • A pathology located in the ileum is in the distal portion of the small intestine (furthest from the point of origin).

  • The jejunum is proximal to the ileum because it appears first along the intestinal journey.

• Upper Extremity Landmarks:

  • Journey origin starts at the shoulder.

  • The elbow is distal to the shoulder, but proximal to the wrist.

  • The wrist is proximal to the hand, but distal to the elbow.

  • The hand is proximal to the fingers.

• Lower Extremity Landmarks:

  • Journey origin starts at the hip.

  • The knee is distal to the hip, but proximal to the ankle.

  • The ankle is proximal to the toes, but distal to the knee.

  • The toes are distal to the ankle.

• Immutability of Anatomical Relationships:

  • Established directional relationships do not change regardless of body orientation (e.g., a patient hanging upside down in a tree) or physical severance (e.g., an amputated arm being radiographed).

  • The elbow remains distal to the shoulder and proximal to the wrist in all circumstances.

Patient Body Positions

• Prone: Lying face down (e.g., position required when receiving a back massage).

• Supine: Lying face up on the back (e.g., position assumed when watching stars at night).

• Fowler's: Semi-sitting or upright sitting position in bed (e.g., position used when eating a meal or watching television in a hospital bed).

• Trendelenburg: Position where the body is laid flat on the back with the feet elevated higher than the head.

• Sims: Side-lying position with the top knee flexed.

Body Planes and Sectioning

• Transverse (Axial / Horizontal) Plane: Divides the body horizontally into superior (upper) and inferior (lower) portions.

• Frontal (Coronal) Plane: Divides the body vertically into anterior (front) and posterior (back) portions.

• Midsagittal (Midsection) Plane: Cuts the body or an organ directly down the midline into two equal left and right halves.

Primary Body Cavities

• Dorsal Cavity: Located posteriorly; houses the organs of the nervous system:

  • Brain

  • Spinal Cord

• Ventral Cavity: Located anteriorly; houses the visceral organs:

  • Heart

  • Stomach

  • Reproductive Organs

Fundamental Chemistry, Atomic Structure, and Chemical Bonds

Hierarchy of Matter

• Atom: The smallest recognizable particle of an element that retains the definitive characteristics of that element.

• Element: The smallest unit of matter that retains the chemical properties of a specific type of matter. Cannot be broken down into smaller substances by routine chemical means (non-routine breakdown occurs in nuclear reactors using elements like uranium to generate steam and electricity).

  • Represented by chemical symbols consisting of one or two letters (e.g., Sodium = $\text{Na}$, Chlorine = $\text{Cl}$, Oxygen = $\text{O}$, Hydrogen = $\text{H}$).

• Molecule: Formed when two or more atoms of the same or different elements combine chemically (e.g., a molecule of water, $\text{H}_2\text{O}$, containing 2 hydrogen atoms and 1 oxygen atom).

• Compound: A substance composed of two or more different elements chemically bound together in fixed proportions (e.g., table salt, $\text{NaCl}$).

Atomic Structure (Bohr's Model)

• Nucleus: The dense central core containing:

  • Protons: Subatomic particles carrying a positive electrical charge ($+1$).

  • Neutrons: Subatomic particles carrying a neutral / zero electrical charge ($0$).

• Electron Shells: Outer orbits surrounding the nucleus containing:

  • Electrons: Subatomic particles carrying a negative electrical charge ($-1$).

• Homeostasis and Neutrality:

  • Under standard conditions, an atom possesses an equal number of protons and electrons, yielding a net charge of zero ($+1 + (-1) = 0$).

• Free Radicals and Antioxidants:

  • Free Radical: An atom or molecule possessing an unpaired electron, giving it an active charge that drives it to seek neutralization by reacting with biological tissue. High levels are linked to cell damage and biological stress.

  • Antioxidants: Compounds that donate electrons to neutralize free radicals without becoming unstable themselves (e.g., blueberries in the diet).

Ions and Ionization

• Ion: An atom or group of atoms that has acquired an electrical charge by gaining or losing one or more electrons.

  • Positively Charged Ion (Cation): Occurs when an atom has more protons than electrons.

  • Negatively Charged Ion (Anion): Occurs when an atom has more electrons than protons.

• Ionization: The physical or chemical process of dissociating a neutral molecule into individual charged ions (e.g., dissolving $\text{NaCl}$ in water separates it into $\text{Na}^+$ and $\text{Cl}^-$ ions).

• Principles of Charge Interaction:

  • Like charges repel one another.

  • Opposite charges attract one another.

  • Proper charge alignment is required for electrical flow (e.g., placing battery terminals in correct orientation to establish current).

The Five Key Chemical Bonds

• Ionic Bond:

  • Formed when one atom completely donates an electron to another atom, creating charged ions that attract each other.

  • Example: Sodium Chloride ($\text{NaCl}$), where sodium donates an electron to chlorine.

• Covalent Bond:

  • Formed when atoms equally share pairs of electrons in their outermost orbital (the valence shell).

  • Example: Methane ($\text{CH}_4$).

• Polar Covalent Bond:

  • Formed when atoms share electrons unequally, causing one side of the molecule to carry a slight negative charge and the other side a slight positive charge.

  • Example: Water ($\text{H}_2\text{O}$), where oxygen holds shared electrons more strongly than hydrogen, allowing water droplets to weakly bind to each other and conduct electricity.

• Peptide Bond:

  • A specialized covalent bond linking the carboxyl group of one amino acid to the amino group of another.

  • Rule: "P for P" — Peptide bonds are found exclusively in Proteins.

• Hydrogen Bond:

  • A weak electrostatic attraction between a hydrogen atom bound to an electronegative atom and another electronegative atom.

  • Examples: Found linking water molecules together and holding the double-helix strands together in Nucleic Acids (DNA/RNA).

Biological Ions, Electrolytes, and Trace Elements

Vital Electrolytes in Physiology

• Electrolytes are ionized minerals dissolved in body fluids that carry electrical charges required for metabolic function:

  • Sodium ($\text{Na}^+$): Crucial for muscle contraction and fluid balance. Fundamental Rule: "Where sodium goes, water follows."

  • Potassium ($\text{K}^+$): Vital for muscle contraction and cardiac signaling.

  • Calcium ($\text{Ca}^{2+}$): Necessary for structural composition of bones and teeth, as well as muscle contraction mechanisms.

  • Magnesium ($\text{Mg}^{2+}$): Essential for bone structure and urinary system functioning.

  • Chloride ($\text{Cl}^-$): Main extracellular anion involved in maintaining fluid and osmotic balance.

  • Hydrogen Phosphate ($\text{HPO}_4^{2-}$) & Bicarbonate ($\text{HCO}_3^-$): Primary chemical buffers maintaining acid-base equilibrium.

• Fluid Replenishment Solutions:

  • Severe gastrointestinal illness (vomiting and diarrhea) depletes both fluid and essential electrolytes, requiring several days for physiological restoration.

  • Gatorade: Formulated in the early 1960s by the team physician for the Florida Gators football team to replenish lost electrolytes after practice.

  • Powerade: Secondary commercial electrolyte formulation (utilized on the Georgia sidelines).

  • Pedialyte: Specifically formulated electrolyte solution for infants and young children experiencing severe fluid loss.

Six Essential Trace Elements

• Out of $21$ trace elements required for human life, six key elements perform central roles:

Water, Solutions, and Inorganic vs. Organic Chemistry

Properties and Physiological Role of Water ($\text{H}_2\text{O}$)

• Water serves as the primary fluid foundation for all bodily fluids and biological processes.

• Hydrophilic vs. Hydrophobic:

  • Hydrophobic ("Water-Fearing"): Non-polar substances that carry no net charge, do not mix with water, and separate when left standing.

  • Examples: Fats, oils, car wax, sunscreen, oxygen ($\text{O}_2$), phosphorus ($\text{P}$), nitrogen ($\text{N}$).

  • Clinical Application: Inpatient cardiac patients on long-term oxygen therapy receive oxygen passed through sterile water ports because pure oxygen gas is dry and severely dehydrates mucous membranes.

  • Safety Caveat: Water must never be poured on a kitchen oil fire because water displaces the burning oil, causing violent splashing and fire spread.

  • Hydrophilic ("Water-Loving"): Polar or charged substances that readily dissolve in or mix with water.

  • Weak hydrogen bonding between water molecules allows a single water droplet to merge with and pick up adjacent droplets.

• Thermal Characteristics: Water possesses a high heat capacity; it absorbs and stores large amounts of heat energy, causing it to heat up and cool down very slowly.

Solutions, Solutes, Solvents, and Concentration

• Solution: A liquid mixture composed of two or more distinct components:

  • Solute: The solid, powder, or gas substance that is dissolved (e.g., Crystal Light powder, Kool-Aid powder, table sugar).

  • Solvent: The liquid substance doing the dissolving (e.g., water, unsweetened tea).

  • Basic Formula: $\text{Solute} + \text{Solvent} = \text{Solution}$

• Concentration: The exact measurement of the amount of solute dissolved relative to the volume of solvent.

  • Standard baseline: $1\text{ packet}$ of Crystal Light per bottle of water yields normal concentration.

  • Adding $2\text{ packets}$ to a single bottle creates an over-concentrated solution.

Inorganic vs. Organic Compounds

• Carbon Criterion: The absolute presence or absence of Carbon ($\text{Carbon}$) determines whether a compound is classified as organic or inorganic.

  • Anthropological Application: Scientists use carbon dating to measure the residual carbon in fossilized bones (such as dinosaur remains) to determine exact age.

• Inorganic Compounds: Molecules lacking carbon atoms in their baseline structure.

  • Water ($\text{H}_2\text{O}$) contains no carbon and is classified as an inorganic compound, despite being mandatory for human survival.

• Organic Compounds: Complex biological molecules containing carbon backbones covalently bonded to hydrogen and other elements.

• Six Core Biological Elements: Carbon ($\text{C}$), Hydrogen ($\text{H}$), Oxygen ($\text{O}$), Nitrogen ($\text{N}$), Sulfur ($\text{S}$), Phosphorus ($\text{P}$).

The Four Major Classes of Biological Molecules

Carbohydrates

• Composed of Carbon, Hydrogen, and Oxygen ($\text{C}\text{H}_2\text{O}$ / carbon plus water). Easily broken down by the body to deliver rapid cellular energy (the brain's primary fuel source).

• Dietary Considerations: Diabetic management (Type 1 and Type 2) focuses on total carbohydrate control—including starches like potatoes, french fries, potato chips, pasta, and natural milk/fruit sugars—not merely refined sweets (cakes, cookies, ice cream).

• Three Classifications of Carbohydrates:

  1. Monosaccharide:

  • A simple, single-sugar unit with a small molecular chain easily absorbed by the body.

  • Glucose: The primary energy source for cellular function ($\text{C}_6\text{H}_{12}\text{O}_6$; calculated by multiplying the base $\text{C}\text{H}_2\text{O}$ molecule by $6$). Glucose tablets are sold in pharmacies to treat low blood sugar (hypoglycemia).

  1. Disaccharide:

  • Formed when two monosaccharide units bind together ($1 + 1 = 2$).

  • Sucrose: Common commercial table sugar, formed by the precise equation: $\text{Glucose} + \text{Fructose} = \text{Sucrose}$.

  1. Polysaccharide:

  • Long, complex chains composed of many linked monosaccharide units ("complex carbohydrates" like whole wheat pasta and whole wheat bread).

  • Digested slowly over time, preventing dramatic spikes in blood glucose and subsequent insulin crashes.

  • Glycogen: The primary storage form of glucose in the body, concentrated mainly in the liver to provide continuous energy during sleep and fasting.

  • Packaging Metaphors: Just as $12\text{ eggs}$ are packaged under the single term "a dozen", dried grapes are called "raisins", and dried plums are called "prunes", a packaged mass of individual glucose molecules is called glycogen.

Glycogen and Glucose Hormonal Regulations

• Glucose Storage Equation (Insulin release):

  • When blood glucose levels rise following food consumption, the pancreas secretes the hormone insulin to signal cells to uptake glucose or convert excess glucose into storage:   $\text{Glucose} + \text{Insulin} \rightarrow \text{Glycogen}$

• Glycogen Breakdown Equation (Glucagon release):

  • When blood glucose drops during fasting or rest, the pancreas secretes the hormone glucagon to break open stored glycogen back into active glucose:   $\text{Glycogen} + \text{Glucagon} \rightarrow \text{Glucose}$

Lipids

• Umbrella term for biological fats, oils, waxes, phospholipids, and steroids composed predominantly of carbon and hydrogen with minimal oxygen. High molecular weight molecules.

• Physiological Roles:

  • Long-term energy storage (e.g., hibernating bears surviving winter on stored fat).

  • Endocrine chemical communication (fat-based hormones).

  • Anatomical physical protection (e.g., the protective fat capsule surrounding each kidney).

• Dietary Rule of Thumb: Limit solid fats at room temperature (e.g., saturated fat surrounding beef steak); consume liquid fats at room temperature (e.g., olive oil, avocado oil).

• Basic Lipid Structure: Composed of $3\text{ fatty acid chains}$ bound to $1\text{ glycerol}$ backbone.

• Emulsification: Because lipids are massive non-polar molecules, they are not broken down by standard chemical digestion; instead, they undergo emulsification (mechanical dispersion into smaller droplets).

• Waxes: Hydrophobic lipids used to repel moisture (e.g., chapstick, car wax).

• Phospholipids: Critical structural constituent of cell membranes forming a lipid bilayer:

  • Head: Hydrophilic ("water-loving"), polar structure containing phosphorus ("waterheads").

  • Tail: Hydrophobic ("water-fearing"), non-polar fatty acid chains resembling the needle end of a seamstress pin.

  • Function: Dual nature allows the cell membrane to precisely manage fluid entry and fluid exit.

• Steroids & Cholesterol:

  • Steroids: Four-ring lipid structures used to reduce tissue inflammation and build tissue (e.g., anabolic steroids used by bodybuilders, medical Z-Paks, steroid-based asthma nebulizer treatments).

  • Cholesterol: Essential structural lipid manufactured entirely by the liver. Dietary excess comes from consuming red meats.

  • Sex Hormones: Lipid-based reproductive molecules: Testosterone (male) and Estrogen (female).

Proteins

• Complex biological polymers made up of fundamental building blocks called amino acids.

  • Metaphor: Amino acids are to proteins as letters are to words; changing the order alters the resultant structure.

• Nitrogen Backbone: Proteins contain nitrogen throughout their primary chemical backbone.

  • Clinical Relevance: Patients with impaired or failing kidneys ("unhappy kidneys") must follow strict low-protein diets because failing kidneys cannot clear excess nitrogen waste products.

• Peptide Bonds: Covalent bonds holding amino acids together in a chain.

• Physiological Roles & Examples:

  • Structural Support: Collagen found in ligaments (attaches bone to bone at joints) and tendons (attaches muscle to bone; visible as the tough rubbery end on a chicken drumstick).

  • Energy Storage: Albumin in egg whites. Egg white albumin is highly identical to human serum albumin manufactured by the liver, making it the most easily absorbed dietary protein source.

  • Movement: Muscle fibers.

  • Immune Protection: Antibodies designed to fight infection.

  • Cellular Communication: Hormonal messengers like insulin.

Nucleic Acids

• High-molecular-weight molecules that direct and control all cellular activities:

  • Deoxyribonucleic Acid (DNA): Located in the cell nucleus; contains deoxyribose sugar (lacking one oxygen atom). Contains inherited genetic instructions making each individual unique.

  • Structure: Double-helix (resembles a twisted flexible ladder).

  • Nitrogenous Bases: Thymine ($\text{T}$), Adenine ($\text{A}$), Cytosine ($\text{C}$), and Guanine ($\text{G}$).

  • Base Pairing Rule: Thymine always pairs with Adenine ($\text{T}-\text{A}$); Guanine always pairs with Cytosine ($\text{G}-\text{C}$). Any alterative pairing creates a genetic mutation resulting in abnormal cellular development.

  • Ribonucleic Acid (RNA): Single-stranded nucleic acid involved in protein translation and cellular control.

• Chemical Bonding: Nucleic acid strands are linked and held together by Hydrogen bonds.

Metabolic Reactions, Enzyme Kinetics, and Cellular Respiration

Reversible Metabolic Reactions

• Reversible chemical reactions are represented by opposing directional arrows ($\rightleftharpoons$), indicating the process can proceed forward or backward depending on cellular needs.

Dehydration Synthesis vs. Hydrolysis

• Dehydration Synthesis:

  • Dehydration: Removal of water.

  • Synthesis: Joining components together ($\text{syn} = \text{coming together}$; e.g., a musical synthesizer putting sounds together, or a synovial joint bringing two bones together).

  • Definition: A metabolic reaction where water is removed to join smaller monomers into a larger complex compound.

  • Metaphor: Removing water from a fresh grape creates a dried raisin.

  • Metabolic Association: Direct mechanism of Anabolism (building up complex compounds).

  • Bodybuilding Application: Consuming high levels of dietary protein to synthesize muscle tissue requires consuming large amounts of water to facilitate dehydration synthesis reactions.

• Hydrolysis:

  • Hydro: Addition of water.

  • Lysis: Breakdown or destruction (e.g., Lysol products spraying to break down dirt and germs).

  • Definition: A metabolic reaction where water is added back to break complex polymers down into basic building blocks.

  • Metabolic Association: Direct mechanism of Catabolism (breaking down complex compounds).

  • Example: Adding water back to break down a protein chain into individual free amino acids.

Characteristics of Enzymes

• Enzyme: Biological protein catalysts that accelerate the speed of metabolic reactions without being consumed in the process.

• The Four Core Characteristics of Enzymes (Rollercoaster Metaphor):

  1. Specific: An enzyme will only interact with one specific substrate (e.g., a children's roller coaster only allows specific riders). The enzyme name consistently matches its substrate and ends in the suffix "-ase":

  • Sucrase acts exclusively on Sucrose.

  • Maltase acts exclusively on Maltose.

  • Lactase acts exclusively on Lactose (lactose-intolerant individuals lack lactase and cannot break down dairy milk sugar; commercial products like Lactaid supply this enzyme).

  • Lipase acts exclusively on Lipids.

  • Proteinase acts exclusively on Proteins.

  • Carbohydrase acts exclusively on Carbohydrates.

  1. Compete: Enzymes compete with similar molecules to bind to active sites on substrate molecules.

  2. Saturate: Because active binding sites are finite (like limited seats on a roller coaster), once all binding sites are filled, the enzyme system becomes fully saturated and reaction rates plateau.

  3. Inhibit: Enzyme action can be blocked, shut off, or slowed down by chemical inhibitors when metabolic products are elevated.

• Enzyme-Substrate Hydrolysis Example:

  • Substrate (Sucrose, a disaccharide) binds to active site of enzyme (Sucrase).

  • Hydrolysis reaction occurs (water added).

  • Products released: $1\text{ molecule}$ of Glucose and $1\text{ molecule}$ of Fructose ($1 + 1 = 2$ disaccharide breakdown).

Cellular Respiration and ATP Production

• Cellular Respiration: The continuous chemical process occurring within cells to convert biochemical energy from food into usable cellular energy.

• Cellular Respiration Equation:   $\text{Glucose} + \text{Oxygen} \rightarrow \text{Carbon Dioxide} + \text{Water} + \text{ATP}$   $\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{ATP}$

• Adenosine Triphosphate (ATP):

  • The primary chemical energy unit of the body, required continuously ($24/7$) for life processes (such as driving diaphragm contraction during sleep).

  • Manufactured inside the Mitochondria (the power plants of the cell).

• ATP / ADP Energy Cycle:

  • ATP (Adenosine Triphosphate): Contains $3\text{ high-energy phosphate bonds}$ (resembles an un-struck match inside a box).

  • When energy is expended, one high-energy phosphate bond is broken, releasing usable heat and energy, converting the molecule into ADP (Adenosine Diphosphate) containing $2\text{ phosphate bonds}$.

  • The cell continuously expends metabolic fuel to re-attach a phosphate group, charging ADP back into ATP ($\text{ADP} \rightarrow \text{ATP}$).

pH Scale, Acid-Base Regulation, and Organ Systems

The pH Scale

• pH Definition: Stands for Potential of Hydrogen ($\text{pH}$; capital $\text{H}$ represents the element Hydrogen). Measures the concentration of free hydrogen ions ($[\text{H}^+]$) in a solution.

• Scale Range: Ranges numerically from $0$ to $14$:

  • $0$ to $6.9$: Acidic.

  • $7.0$: Absolutely Neutral (e.g., pure cytoplasm inside cells).

  • $7.1$ to $14$: Basic (Alkaline).

• Inverse Relationship Rule:

  • The lower the pH value, the higher the concentration of released hydrogen ions ($[\text{H}^+]$), making the substance more strongly acidic.

  • The higher the pH value, the lower the concentration of released hydrogen ions ($[\text{H}^+]$), making the substance more strongly basic / alkaline.

Characteristics of Acids and Bases

• Acids:

  • Electrolytes that dissociate in water to release active hydrogen ions ($\text{H}^+$).

  • Taste sour, act as corrosive agents breaking down compounds.

  • Examples: Hydrochloric acid ($\text{pH} = 0$), stomach acid, orange juice, black coffee, urine (urine is acidic; during a urinary tract infection, acidic urine irritates the inflamed bladder wall. OTC medication Azo Standard / Pyridium alters urine pH to alleviate acute pain).

• Bases (Alkaline):

  • Electrolytes that absorb or accept free hydrogen ions ($\text{H}^+$), neutralizing acidity.

  • Taste bitter (think b for bitter).

  • Basic substances can cause chemical burns equal to strong acids.

  • Examples: Human blood ($\text{pH} = 7.4$, slightly basic), pancreatic juice, cytoplasm ($\text{pH} = 7.0$), household bleach, household ammonia, sodium hydroxide, baking soda (bicarbonate antacid recipe: $1\text{ tsp}$ baking soda dissolved in $8\text{ oz}$ water).

  • Warning: Household bleach and ammonia must never be mixed together due to toxic gaseous chemical reactions.

Systemic Acid-Base Management

• Two primary organ systems actively control and maintain systemic acid-base equilibrium:

  1. Respiratory System (Primary System):

  • Acts as the primary rapid-response manager of acid-base balance.

  • Carbon dioxide ($\text{CO}_2$) dissolved in blood forms a mild acid. Exhaling $\text{CO}_2$ clears acid from the body.

  • Yawning is an involuntary respiratory response that forcefully expels excess built-up $\text{CO}_2$ when poor posture or lethargy reduces shallow breathing efficiency.

  1. Urinary System (Secondary / Backup System):

  • Acts as the secondary manager by excreting or reabsorbing hydrogen ions and bicarbonate in urine.

• Pathological Cascade Example:

  • Severe lung disease (e.g., pneumonia, bronchitis, COPD, emphysema) impairs the respiratory system (primary system), preventing $\text{CO}_2$ clearance.

  • The urinary system (secondary system) attempts to compensate but becomes severely overworked.

  • Uncompensated metabolic overload leads to renal failure, systemic sepsis, and death (e.g., the case of 36-year-old NASCAR figure who died from severe pneumonia progressing into renal failure and sepsis).

Questions & Discussion

• Student Peer Introductions & Career Goals:

  • Lavonda (25): Goal is to become a specialized nurse in oncology and hematology.

  • Sandra (22): Serving as an EMT in the military to utilize educational benefits to fund nursing school.

  • Baby Lane (16): High school student attending college through dual enrollment.

  • Behavioral Health Technician Student: Currently works as a behavioral health technician; returned to school for nursing to earn higher compensation despite workplace challenges.

• Study Habits and AI Learning Tools:

  • Students discussed studying in the campus library to utilize physical human anatomical skeletons and whiteboards to avoid home distractions.

  • Students discussed utilizing NotebookLM and ChatGPT AI to generate practice quizzes, synthesize podcast summaries, and convert course notes into study guides.

• Class Response System Review Questions & Answers:

  • Question: What is a charged atom or molecule?

  • Answer: Ion.

  • Question: What is the smallest unit of matter retaining chemical properties of an element?

  • Answer: Element.

  • Question: What are the smallest particles retaining characteristics of an element?

  • Answer: Atom.

  • Question: What is formed when two or more elements combine?

  • Answer: Molecule.

  • Question: What weak bond gives water its unique cohesive properties?

  • Answer: Polar covalent bond (and hydrogen bonding).

  • Question: A Siberian plant discovery reveals a hydrophobic, waxy covering. What class of biological molecule is this?

  • Answer: Lipid.

  • Question: A solution with a pH of $8$ is classified as what?

  • Answer: Basic (Alkaline).

  • Question: What bond type results in a molecule carrying a slight charge due to unequal sharing?

  • Answer: Polar covalent bond.

  • Question: What term describes the total amount of solute dissolved in a solvent?

  • Answer: Concentration.

  • Question: Which of the following is NOT a biological molecule: Sodium chloride, Glucose, Testosterone, or DNA?

  • Answer: Sodium chloride (it is an inorganic salt).

  • Question: What element forms the structural backbone of amino acids and proteins?

  • Answer: Nitrogen.

  • Question: What class of metabolic reactions breaks down complex molecules?

  • Answer: Catabolism (via Hydrolysis).

  • Question: How is saturation defined in enzyme kinetics?

  • Answer: No available binding sites remaining.

  • Question: Which statement is true of enzyme reactions?

  • Answer: Enzymes can be blocked or inhibited.

  • Question: Which molecule carries more available energy: ATP or ADP?

  • Answer: ATP.

Exam Readiness Logistics

• Required Exam Supplies: Standard Scantron form, two $\text{No. 2}$ pencils.

• Assessment Mandate: The online Reflection Assessment is strictly due at $11:00\text{ PM}$ the night before the scheduled unit exam.