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Questions and Answers

Which of the following describes anabolic processes?

  • Release energy
  • Break down complex molecules into simple ones
  • Build complex molecules from simple ones (correct)
  • Require energy (correct)

    • Photosynthesis is a catabolic process.

    False

    Cellular respiration is a catabolic process.

    True

    Cellular respiration is an oxidation-reduction reaction.

    <p>True</p> Signup and view all the answers

    What happens to glucose during cellular respiration?

    <p>It is broken down into carbon dioxide and water</p> Signup and view all the answers

    What is the main energy currency of cells?

    <p>ATP</p> Signup and view all the answers

    The energy stored in ATP is analogous to a compressed spring.

    <p>True</p> Signup and view all the answers

    What is the process of breaking down ATP to release energy called?

    <p>Hydrolysis</p> Signup and view all the answers

    How can the energy released from ATP hydrolysis be used by cells? (Select all that apply)

    <p>Muscle cell contraction</p> Signup and view all the answers

    Cellular respiration takes place in the cytoplasm.

    <p>False</p> Signup and view all the answers

    Which of the following is NOT a stage of cellular respiration?

    <p>Photosynthesis</p> Signup and view all the answers

    Where does glycolysis take place?

    <p>Cytoplasm</p> Signup and view all the answers

    What are the products of glycolysis?

    <p>Two pyruvate molecules, two ATP molecules and two NADH molecules</p> Signup and view all the answers

    Where does pyruvate oxidation take place?

    <p>Mitochondrial matrix</p> Signup and view all the answers

    What is the product of pyruvate oxidation?

    <p>Acetyl-CoA, and two NADH and a CO2 molecule are released</p> Signup and view all the answers

    Where does the citric acid cycle occur?

    <p>Mitochondrial matrix</p> Signup and view all the answers

    What are the products of the citric acid cycle?

    <p>Two CO2 molecules, three NADH molecules, one FADH2 molecule and one ATP molecule are produced</p> Signup and view all the answers

    Where does oxidative phosphorylation occur?

    <p>Inner mitochondrial membrane</p> Signup and view all the answers

    What are the two main components of oxidative phosphorylation?

    <p>Electron transport chain and chemiosmosis</p> Signup and view all the answers

    The electron transport chain and chemiosmosis produce the most ATP.

    <p>True</p> Signup and view all the answers

    What are the electron carriers in cellular respiration?

    <p>NAD+ and FAD</p> Signup and view all the answers

    What is the main product of lactic acid fermentation?

    <p>Lactic Acid</p> Signup and view all the answers

    What are the main products of alcoholic fermentation?

    <p>Ethanol and carbon dioxide</p> Signup and view all the answers

    Fermentation produces more ATP than aerobic respiration.

    <p>False</p> Signup and view all the answers

    Fermentation allows glycolysis to continue when oxygen is scarce.

    <p>True</p> Signup and view all the answers

    Where is pyruvate converted to Acetyl-CoA?

    <p>Mitochondrial matrix</p> Signup and view all the answers

    Oxaloacetate is a product of the citric acid cycle.

    <p>False</p> Signup and view all the answers

    The citric acid cycle is a key step in the oxidation of glucose to CO2.

    <p>True</p> Signup and view all the answers

    The electron transport chain generates a proton gradient across the inner mitochondrial membrane.

    <p>True</p> Signup and view all the answers

    Chemiosmosis utilizes the proton gradient generated by the electron transport chain to produce ATP.

    <p>True</p> Signup and view all the answers

    Anaerobic cellular respiration is a major source of ATP in most organisms.

    <p>False</p> Signup and view all the answers

    What is the function of osmoregulation?

    <p>Regulating the uptake and loss of water and solutes</p> Signup and view all the answers

    What is osmolarity?

    <p>The total concentration of solutes in a solution</p> Signup and view all the answers

    What is the approximate osmolarity of body fluids in mammals?

    <p>300 mOsm/L</p> Signup and view all the answers

    Match the following solutions with their descriptions:

    <p>Hypotonic solution = A solution that is more dilute than the cell's internal environment. Isotonic solution = A solution that has the same osmolarity as the cell's internal environment. Hypertonic solution = A solution that is more concentrated than the cell's internal environment.</p> Signup and view all the answers

    What happens to an animal cell placed in a hypotonic solution?

    <p>The cell swells</p> Signup and view all the answers

    Osmoconformers are organisms that actively regulate their internal osmolarity.

    <p>False</p> Signup and view all the answers

    Which of the following organisms is an osmoconformer?

    <p>Starfish</p> Signup and view all the answers

    What is the main challenge for freshwater fish with regards to osmoregulation?

    <p>Gaining water and losing salts</p> Signup and view all the answers

    What is the main challenge for marine fish with regards to osmoregulation?

    <p>Losing water and gaining salts</p> Signup and view all the answers

    Diadromous fish are fish that can live in both freshwater and saltwater environments.

    <p>True</p> Signup and view all the answers

    What is the function of salt glands in marine birds?

    <p>To filter out excess salt from their blood</p> Signup and view all the answers

    Land animals are not affected by water loss.

    <p>False</p> Signup and view all the answers

    Which of the following is NOT a mechanism to reduce water loss in land animals?

    <p>Increased sweating</p> Signup and view all the answers

    All land animals produce ammonia as their primary nitrogenous waste.

    <p>False</p> Signup and view all the answers

    What is the main function of the excretory system?

    <p>To control body fluid solute concentrations and dispose of metabolic wastes</p> Signup and view all the answers

    The kidney is the main organ of the excretory system in mammals.

    <p>True</p> Signup and view all the answers

    What is the functional unit of the kidney?

    <p>Nephron</p> Signup and view all the answers

    The glomerulus is a bundle of capillaries in the nephron.

    <p>True</p> Signup and view all the answers

    The Bowman's capsule is where urine is collected.

    <p>False</p> Signup and view all the answers

    The collecting duct carries urine to the renal pelvis.

    <p>True</p> Signup and view all the answers

    What is the role of ADH in regulating fluid retention?

    <p>It increases the reabsorption of water in the collecting duct</p> Signup and view all the answers

    What is the function of aquaporins in the collecting duct?

    <p>To increase water permeability</p> Signup and view all the answers

    Diuretics increase the amount of water reabsorbed in the kidneys.

    <p>False</p> Signup and view all the answers

    The renin-angiotensin system (RAS) is involved in regulating blood volume, independent of osmolarity.

    <p>True</p> Signup and view all the answers

    The renin-angiotensin system (RAS) decreases blood pressure.

    <p>False</p> Signup and view all the answers

    What is the main function of the circulatory system?

    <p>To transport substances throughout the body and between the body and environment</p> Signup and view all the answers

    Which of the following is NOT transported by the circulatory system?

    <p>DNA</p> Signup and view all the answers

    What are the two main mechanisms of transport within the circulatory system?

    <p>Convection and diffusion</p> Signup and view all the answers

    Diffusion can transport substances over long distances.

    <p>False</p> Signup and view all the answers

    Flatworms primarily rely on diffusion for internal transport.

    <p>True</p> Signup and view all the answers

    Most organisms rely on a combination of diffusion and convection for transport.

    <p>True</p> Signup and view all the answers

    Which of the following components is NOT typically found in a circulatory system?

    <p>Nervous system</p> Signup and view all the answers

    What is the function of the pump in a circulatory system?

    <p>To move circulatory fluid</p> Signup and view all the answers

    Closed circulatory systems have blood confined to blood vessels.

    <p>True</p> Signup and view all the answers

    Closed circulatory systems are more efficient than open circulatory systems.

    <p>True</p> Signup and view all the answers

    What is the main type of circulatory system found in vertebrates?

    <p>Closed circulation</p> Signup and view all the answers

    What is the main type of circulatory system found in arthropods?

    <p>Open circulation</p> Signup and view all the answers

    Which of the following is a key function of capillaries?

    <p>To exchange materials between blood and tissues</p> Signup and view all the answers

    Blood flow is faster in capillaries than in arteries.

    <p>False</p> Signup and view all the answers

    Arteries are thicker walled than veins.

    <p>True</p> Signup and view all the answers

    Veins have valves to prevent backflow of blood.

    <p>True</p> Signup and view all the answers

    What is the function of the lymphatic system?

    <p>To collect excess fluid and return it to the blood</p> Signup and view all the answers

    The lymphatic system is a closed circulatory system.

    <p>False</p> Signup and view all the answers

    Laminar flow is a type of blood flow where all layers of blood move at the same speed.

    <p>False</p> Signup and view all the answers

    Blood vessel diameter has no effect on flow rate.

    <p>False</p> Signup and view all the answers

    What is the main mechanism by which blood flow is regulated in the body?

    <p>Changes in blood vessel diameter</p> Signup and view all the answers

    Vasoconstriction is the narrowing of blood vessels.

    <p>True</p> Signup and view all the answers

    Vasodilation is the widening of blood vessels.

    <p>True</p> Signup and view all the answers

    Precapillary sphincters are located at junctions between arteries and veins.

    <p>False</p> Signup and view all the answers

    Plaques in blood vessels can reduce blood flow and lead to heart attack.

    <p>True</p> Signup and view all the answers

    Fish have a double circulatory system.

    <p>False</p> Signup and view all the answers

    Mammals have a single circulatory system.

    <p>False</p> Signup and view all the answers

    What is the main advantage of a double circulatory system?

    <p>It allows for more efficient transport of oxygen and nutrients</p> Signup and view all the answers

    The mammalian heart has four chambers.

    <p>True</p> Signup and view all the answers

    The atria are thicker walled than the ventricles.

    <p>False</p> Signup and view all the answers

    Match the following chambers of the heart with their functions:

    <p>Right atrium = Receives deoxygenated blood from the body Right ventricle = Pumps deoxygenated blood to the lungs Left atrium = Receives oxygenated blood from the lungs Left ventricle = Pumps oxygenated blood to the body</p> Signup and view all the answers

    Study Notes

    Cellular Respiration - Overview

    • Cellular respiration is a metabolic pathway
    • Includes both anabolic and catabolic reactions
    • Anabolic reactions require energy to build complex molecules from simple ones
    • Catabolic reactions release energy by breaking down complex molecules into simpler ones
    • Photosynthesis and cellular respiration are interconnected cycles within an ecosystem
    • Photosynthesis uses light energy to convert CO2 and H2O into organic molecules and O2
    • Cellular respiration uses organic molecules and O2 to produce ATP, the energy currency of cells, and releases CO2 and H2O
    • Glucose is oxidized to CO2 by removing H+ and electrons
    • Electrons are transferred to O2 to form water
    • The process releases energy used to make ATP

    Cellular Respiration - an Oxidation Reduction Reaction

    • Oxidation is the loss of electrons (e⁻, H⁺)
    • Reduction is the gain of electrons (e⁻, H⁺)
    • Glucose undergoes oxidation, losing H⁺ and e⁻ to become CO2
    • Oxygen gains H⁺ and e⁻ to become water
    • This change is an oxidation-reduction reaction

    Cellular Respiration - stepwise Oxidation of Glucose

    • Electrons are transferred in a stepwise fashion during cellular respiration
    • This stepwise transfer releases energy slowly which can be harnessed as the energy moves to electronegative oxygen
    • This slow release allows cells to recover/capture the energy for cellular function

    ATP - Adenosine Triphosphate

    • Adenosine triphosphate (ATP) is the energy currency of cells
    • Made from adenine, ribose, and 3 phosphate groups (triphosphate)
    • Phosphate groups show mutual repulsion, like storing energy in a compressed spring
    • ATP can be hydrolyzed (broken down with water) to release energy to do work in cells

    ATP Powers Cellular Work

    • ATP powers various cellular work by transferring a phosphate group to other molecules causing them to change shape.
    • Examples include
      • Building large molecules from smaller ones
      • Transporting substances across membranes
      • Muscle cell contraction

    Cellular Respiration Stages

    • Glycolysis (cytosol): Glucose (6C) turns into 2 pyruvates (3C) and some ATP. 
    • Pyruvate oxidation (mitochrondrial matrix): Pyruvate (3C) turns into 2C + CO₂
    • Citric acid cycle (mitochrondrial matrix): 2C turns into CO2 + CO2
    • Oxidative phosphorylation (inner mitochondrial membrane): H⁺ and e⁻ that were removed from sugar are transferred step-wise to O₂, producing most ATP

    Electron Carriers

    • NAD⁺ and FAD are molecules that carry H⁺ and e⁻ to electron transport chain, allowing the electrons to reach oxygen

    Cellular Respiration – Glycolysis and Fermentation

    • If O2 is not present, fermentation occurs
    • Pathways in fermentation regenerate NAD⁺
    • Alcohol fermentation produces ethanol and CO2
    • Lactic acid fermentation produces lactic acid

    If O₂ is present aerobic cellular respiration proceeds

    • If oxygen is present, aerobic cellular respiration proceeds
    • Pyruvate is converted to acetyl CoA, then enters the citric acid cycle
    • Citric acid cycle produces NADH and FADH2 which carry electrons

    Cellular Respiration Stages (alternative format)

    • Glycolysis: glucose (6C) to pyruvate (2 x 3C) to some ATP, 2 NADH
    • Pyruvate oxidation: pyruvate (3C) - CO₂ (1C) to Acetyl-CoA (2C) - NADH
    • Citric Acid Cycle: Acetyl-CoA (2C) to CO₂ (2 x 1C), 3 NADH, 1 FADH2, 1 ATP
    • Oxidative phosphorylation: Electrons carried by NADH and FADH2 are shuttled through the electron transport chain to oxygen. Also chemiosmosis for majority of ATP created.

    Pyruvate oxidation in mitochondrial matrix

    • Pyruvate's carboxyl (-COO) group is released, then converted to CO2
    • The remaining 2-carbon compound gets oxidized and bonds with coenzyme A turning it into Acetyl-CoA
    • Products Include: CO2; NADH (electron carrier); Acetyl-CoA (high energy)

    Citric Acid Cycle

    • The citric acid cycle completes the oxidation of the acetyl-CoA into CO2
    • Other products produced during the cycle includes ATP and electron carriers (NADH and FADH2)

    Cellular Respiration Stages (Summary)

    • Glycolysis: glucose (6C) converts to two pyruvates (3C), 2 ATP, 2 NADH (cytosol)
    • Pyruvate oxidation: 2 pyruvates (3C) converts to 2 Acetyl-CoA (2C), 2 CO₂, 2 NADH (mitochondrial matrix)
    • Citric acid cycle: 2 Acetyl-CoA (2C) converts to 4 CO2, 6 NADH, 2 FADH2, 2 ATP (mitochondrial matrix)
    • Oxidative phosphorylation: Electron carriers deliver electrons (NADH and FADH₂) to the electron transport chain and chemiosmosis creates the majority of ATP. (Inner mitochondrial membrane)

    Electron Transport Chain (Summary)

    • Stepwise transfer of electrons down the chain to oxygen
    • Releases energy used to pump protons (H⁺) across the inner mitochondrial membrane
    • Protons drive ATP synthesis during chemiosmosis
    • Electrons are carried by NADH and FADH2

    Electron Transport Chain + Chemiosmosis (Summary)

    • The electron transport chain passes electrons from carriers (NADH and FADH2) to oxygen
    • Energy released is used to pump H⁺ across the mitochondrial membrane
    • Creates a proton gradient driving ATP synthesis via ATP synthase

    Overall energy flow in cellular respiration

    • Glucose's energy is passed to NADH and, to a lesser extent, FADH2
    • The energy in these electron carriers is used to create a proton gradient that powers ATP production
    • The final electron acceptor is oxygen

    Anaerobic Cellular Respiration

    • An alternative process to aerobic respiration, where an electronegative molecule other than oxygen, such as sulfate, is used to accept electrons

    Osmoregulation (intro)

    • Homeostasis is maintaining internal balance despite environmental changes
    • Maintaining constant conditions in temperature, nutrient availability, oxygen and osmolarity are examples

    Osmoregulation

    • Osmolarity is the total concentration of dissolved substances in a solution
    • Water moves from low to high solute concentration (high to low free water concentration )
    • Mammals typically use osmoregulation to maintain their internal osmolarity.
    • Some marine invertebrates use osmoconforming to maintain isotonic osmolarity to their external environment
    • Osmoregulatory systems control body fluid solute concentrations and dispose of metabolic wastes
    • Excretory systems vary considerably between organisms based on habitat (freshwater, marine, terrestrial) 

    Water Balance in Animal Cells

    • Different concentrations of solutes in a solution determine if an animal cell will gain or lose water (hypotonic, hypertonic, isotonic)

    Some Marine Organisms

    • Most marine invertebrates are osmoconformers, allowing their internal osmolarity to change to match their surroundings, even if the surroundings change
    • Examples of habitats with changing osmolarity include tide pools and estuaries 

    Osmocconformers & Isotonicity

    • Osmocconformers maintain an internal osmolarity that is almost the same as the external osmolarity
    • They adjust their internal organic solutes to match the external environment

    Green Crabs

    • Green crabs are predominantly osmoconformers, meaning they match their body fluids to the surrounding waters
    • Can be osmoregulators in habitats of changing osmolarity

    Osmoregulators

    • Osmoregulators control internal osmolarity by countering passive losses or gains of water and solutes
    • Different mechanisms exist to counter water/solute loss or gains in freshwater, marine and terrestrial animals

    Example Osmoregulator (Fish)

    • Freshwater fish lose water/gain salts by diffusion, countered by drinking water and active ion uptake at gills
    • Marine fish gain water/lose salts by diffusion, countered by drinking seawater and excreting concentrated urine
    • Fish that migrate between environments will need to adjust their osmoregulatory systems

    Marine Birds and Reptiles

    • Birds and reptiles that drink seawater use salt glands to actively secrete excess salts
    • Salt glands filter out excess salts which are expelled from their nostrils

    Water Loss in Land Animals

    • Terrestrial animals lose water to the surroundings, making it vital to maintain water levels.
    • Different mechanisms exist to reduce water loss

    Regulating Excretion

    • Excretory systems control body fluid solute concentrations and dispose of metabolic wastes
    • Nitrogenous waste comes from breaking down proteins and nucleic acids

    Forms of Nitrogenous Wastes

    • Ammonia: inexpensive, toxic, good only in aquatic environments
    • Urea: more expensive, less toxic compared to ammonia
    • Uric acid: most expensive, non-toxic, best in terrestrial organisms

    Mammalian Excretory System: Kidney

    • Nephron is the functional unit of the kidney, filtering fluids to form urine
    • Urine empties into the renal pelvis

    Nephron

    • Sieves the filtrate from blood, and reclaims H₂O, vitamins, and nutrients as needed
    • Dumps everything else (nitrogenous waste) into the renal pelvis

    Regulation of fluid retention by ADH

    • Osmoreceptors detect blood osmolarity changes, triggering ADH release
    • Higher blood osmolarity leads to increased ADH to reabsorb more water which reduces overall blood osmolarity, lowering urine volume

    ADH increases aquaporins (summary)

    • ADH increases the number of aquaporins (water channels) in the collecting ducts of nephrons in the kidney
    • Increased H₂O reabsorption lowers urine volume and increases urine osmolarity
    • Diuretics inhibit ADH, increasing urine volume

    Renin-angiotensin system (RAS)

    • RAS regulates blood volume, independent of osmolarity
    • Responds to a drop in blood pressure causing an increase of water/salt reabsorption by the kidney
    • Doesn't control osmolarity directly

    Circulation (overview)

    • Circulation is transport throughout the organism and/or between organism and environment using O2, CO2, Nutrients, Waste, Hormones, Immune Factors and Heat.
    • Two main transport mechanisms exist, diffusion and convection

    Circulation - 2 Transport Systems

    • Diffusion: for short distances, cells near the environment
    • Convection: bulk flow of body fluids by pumps for larger distances

    General Design of Circulatory Systems

    • Circulatory systems need pumps (heart or cilia), tubes for moving fluid (blood vessels) and exchange areas (capillaries)

    Open vs. Closed Circulatory Systems

    • Open: fluid not confined to vessels, bathes organs directly. Examples are arthropods.
    • Closed: fluid confined to vessels, creating pressure allowing for efficient delivery to tissues. Examples are annelids, and vertebrates.

    Closed Circulatory System (Cardiovascular System)

    • Arteries: blood from heart to capillaries
    • Capillaries: diffusion between blood and tissues
    • Veins: blood returns to the heart

    Blood Vessel Structure

    • Arteries have thicker walls, providing strength to withstand high pressure
    • Veins have thinner walls, helping blood return to the heart
    • Capillaries have thin walls for efficient gas and nutrient exchange

    Blood Vessel Structure (Capillaries)

    • Capillaries have thin walls that allow for material exchange between blood and interstitial fluid
    • The narrow diameter slows flow, facilitating efficient exchange

    Fluid and Proteins Leak

    • Fluid and proteins leak from blood capillaries into the interstitial fluid
    • Lymphatic vessels collect this fluid, returning it to the circulatory system

    Modeling Fluid Flow

    • Laminar flow: layers of fluid move past each other, overcoming friction
    • Poiseulle's Law: flow rate is proportional to the radius to the fourth power; change in radius has the greatest effect on flow rate

    Blood Flow Regulation

    • Vasoconstriction: constricting to reduce blood flow
    • Vasodilation: relaxing to increase blood flow
    • Precapillary sphincters: control blood flow into capillaries

    Plaques (Fatty Deposits)

    • Plaques narrow blood vessels reducing blood flow to tissues
    • Can cause heart attacks if the flow of oxygen is impacted.

    Closed Circulation: Single vs. Double Circulation

    • Single: blood pumped once through the body (fish)
    • Double: blood pumped twice through the body (mammals, and other animals)

    Mammalian Heart

    • Atria: thinner walls; collect returning blood
    • Ventricles: thicker walls; contract forcefully to pump blood

    Mammalian Cardiovascular System

    • Blood flows from the heart to the lungs and back to the heart to be pumped to the rest of the body

    Spread of Depolarization

    • Depolarization spreads across the heart chambers via gap junctions, allowing coordinated contraction

    Gap Junctions (Summary)

    • Protein channels that connect neighboring cells’ cytoplasm
    • Allow for the transmission of electrical signals between cells, allowing the coordinated contraction of the heart

    Pacemaker Cells

    • Pacemaker cells in the sinoatrial (SA) node initiate the heart's rhythmic contractions

    Heart Contractions and Relaxation (Cardiac Cycle)

    • Systole: contraction phase
    • Diastole: relaxation/filling phase

    Valves (Summary)

    • Atrioventricular valves: prevent backflow from ventricles to atria
    • Semilunar valves: prevent backflow from arteries to ventricles

    Gas Exchange (overview)

    • Gas exchange involves taking up O2 from the environment and releasing CO2
    • Steps include: convection, diffusion and convection as well as diffusion back to the cells

    Partial Pressures (summary)

    • Partial pressure is the pressure exerted by a particular gas in a mixture of gases
    • Gases move down partial pressure gradients from high to low partial pressure

    Gases Diffuse (summary)

    • O2 diffuses into blood at the alveolar surface (lungs)
    • O2 combines with respiratory pigment (hemoglobin in blood)
    • O2 diffuses from blood to tissues
    • CO2 diffuses from tissues into blood and then to the alveolar spaces

    Respiratory Surfaces

    • Respiratory surfaces have extensive surface area for fast diffusion of gases. 

    O2 Diffuses into Red Blood Cells

    • O2 dissolves in plasma, but hemoglobin in blood significantly increases O2 carrying capacity.

    Pulse Oximeters

    • Measure blood oxygen saturation levels using changes in light absorption

    Cooperativity & O2 Binding/Release

    • Hemoglobin with more bound oxygen binds more tightly (cooperativity) at high PO2, promotes loading at lungs
    • Lower PO2, causes hemoglobin to bind less tightly, promotes unloading in tissues

    CO2 Promotes O2 Unloading

    • CO2, through increased H+, lowers hemoglobin’s affinity for O2
    • Increases O2 unloading at active tissues

    Bohr Shift

    • CO2 and H⁺ decrease hemoglobin’s affinity for O2, increasing unloading

    Hemoglobin Facilitates CO2 & O2 Transport

    • CO2 is transported as bicarbonate (HCO3-) in plasma and bound to hemoglobin
    • CO2 is unloaded from blood at the lungs
    • Breathing removes exhaled CO2

    Breathing Control Coordinates Gas Exchange

    • Medulla oblongata receives signals (pH of cerebrospinal fluid) to regulate breathing based on metabolic demand

    Transport of Respiratory Gases

    • O2 diffuses into blood, then bound to hemoglobin leading to oxyhemoglobin
    • CO2 diffuses from tissues, dissolved in plasma, turning into carbonic acid.

    Immunology (overview)

    • Immunology focuses on how organisms detect and combat pathogens.
    • Two main categories of immunity exist: innate and adaptive

    Innate vs. Adaptive Immunity

    • Innate: present in all animals; broad recognition of pathogens; rapid response
    • Adaptive: present only in vertebrates; specific recognition of pathogens; slower response

    Innate Immunity - Barrier Defenses

    • Physical barriers (skin, mucous membranes) and chemical barriers (lysosomes, stomach acid, low pH secretions) are first line of defense
    • The barrier defenses limit pathogen entry

    Innate Immunity - Internal Defenses

    • Phagocytic cells: engulf and digest pathogens
    • Natural killer cells: kill infected cells
    • Antimicrobial proteins: attack pathogens directly
    • Inflammatory response: localized systemic pathogen response

    Innate Immunity - Inflammatory Response

    • Mast cells release histamine and cytokines to signal an immune response; leading to redness, swelling, heat/pain and the build up of neutrophils to the infection area

    Neutrophils (Summary)

    • Neutrophils migrate through capillary walls, engulf pathogens, and are a component in the inflammatory response

    Adaptive Immunity (Vertebrates)

    • Adaptive immunity remembers past pathogens; responds specifically and mounts a large response to them the second time a pathogen is present to the organism
    • Involves lymphocytes (T and B cells)
    • Has a large diversity of receptors

    B-cell and T cell Receptors

    • B and T cells have specific receptors for antigens; diverse receptors allow them to match to almost any antigen that could encounter them
    • Diverse receptors for antibodies (B cells)
    • Receptors for the antigens presented to the cytotoxic T cells (T cells)

    Receptor Diversity

    • Receptor diversity is generated from different combinations of receptor subunits
    • Large diversity is produced from genetic rearrangements of the receptor subunits from a smaller set of genes

    Antigen Receptors form During Differentiation

    • T-cells that mature in the thymus; B-cells that mature in the bone marrow

    Adaptive Immune Response Formation

    • Pathogens that encounter matching receptors will interact and trigger a larger immune response
    • Pathogens move to lymph nodes to encounter lymphocytes
    • Recognition triggers cell division

    B Cells Activation

    • Antigens bind with B-cell receptors, triggering clonal expansion, creating memory cells and plasma cells
    • Plasma cells secrete antibodies which neutralize or destroy pathogens

    Immunological Memory

    • Primary response: slower, smaller response to an antigen exposure initially
    • Secondary response: faster, stronger response to a repeated encounter to the same antigen

    Effector Cells (Summary)

    • Effector B cells (plasma cells) secrete antibodies
    • Cytotoxic T cells kill infected cells

    Antibodies from Plasma Cells

    • Neutralization: blocks pathogen interaction
    • Opsonization: tags pathogens for phagocytosis
    • Activation of complement proteins: creates membrane attack complex that forms pore in pathogens, rupturing the pathogens

    Cytotoxic T Cells Activation

    • Cytotoxic T cell activation requires a helper T cell that recognizes the antigen and the cytotoxic T cell binding to the antigen.

    Activated Helper T Cells

    • Activated helper T cells divide to create more helper T cells, memory helper T cells, and cytotoxic T cells

    B Cells Present Antigens

    • In addition to antigen-receptor binding, B cells can present antigens to helper T cells
    • This interaction triggers the expansion of B cells and the generation of plasma cells

    Cytotoxic T Cells (Two-Step activation)

    • Activated by cytokines from activated helper T cells
    • Attaching to infected cell antigens presented on the surface via Class I MHC proteins

    Vaccines

    • Vaccines provide a safe way to induce a primary immune response
    • mRNA vaccines trigger the production of specific antigens that elicit an immune response which results in immunological memory.

    Immunization Programs

    • Immunization programs have dramatically reduced the incidence of many diseases.

    COVID-19 Vaccines

    • Vaccine trials demonstrated high efficacy and few adverse effects.

    Lyme Disease Vaccine

    • No widely available Lyme disease vaccine currently.

    Cellular Respiration (Summary - updated)

    • Glycolysis: Glucose (6C) → 2 Pyruvate (3C) + 2 ATP + 2 NADH (cytoplasm).
    • Pyruvate Oxidation: 2 Pyruvate (3C) → 2 Acetyl CoA (2C) + 2 CO₂ + 2 NADH (mitochondrial matrix).
    • Citric Acid Cycle: 2 Acetyl CoA (2C) → 4 CO₂ + 6 NADH + 2 FADH₂ + 2 ATP (mitochondrial matrix).
    • Oxidative Phosphorylation: Electron carriers (NADH and FADH₂) release electrons to the electron transport chain creating a proton gradient to drive ATP synthesis in chemiosmosis (inner mitochondrial membrane).

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