Protein and Lipid Digestion, Glycolysis, and Physiology Practice Flashcards

Comprehensive vocabulary flashcards covering basic thermodynamics, metabolism (glycolysis, Krebs, ETC), and human respiratory and cardiovascular physiology.

First Law of Thermodynamics

Energy cannot be created or destroyed, only change forms, such as chemical energy in food converting to $ATP$.

Second Law of Thermodynamics (Entropy)

The principle that systems naturally move toward greater disorder (entropy) unless energy is added to maintain organization.

OIL RIG

A mnemonic for Redox reactions: Oxidation Is Loss (of electrons/hydrogens), Reduction Is Gain (of electrons/hydrogens).

ATP (Adenosine Triphosphate)

The main cellular energy currency; it stores energy in negative phosphate groups that repel each other.

$$\Delta G \approx -32\,kJ/mol$$

The approximate amount of energy released when a phosphate bond is broken in the reaction $ATP \rightarrow ADP + Pi$.

NAD+

The oxidized form of an electron carrier that accepts electrons to become $NADH$.

FADH2

The reduced form of the electron carrier $FAD$ used to transport high-energy electrons to the electron transport chain.

Proteases

Enzymes that digest proteins into amino acids, including pepsin, trypsin, and chymotrypsin.

Pepsin

An enzyme located in the stomach that works best at an acidic $pH$ of approximately $2$.

Deamination

The process of removing the amino group ($NH_2$) from amino acids, resulting in toxic ammonia ($NH_3$) and a carbon skeleton.

Negative Feedback

A regulatory mechanism where the product of a pathway inhibits the pathway to maintain homeostasis, such as high $ATP$ levels decreasing deamination.

Beta Oxidation

A process where fatty acids are broken into $2$-carbon acetyl-CoA units, generating $NADH$ and $FADH_2$.

Glycolysis

An anaerobic process in the cytoplasm that breaks glucose into two pyruvates, yielding a net of $2\,ATP$ and $2\,NADH$.

Phosphofructokinase (PFK)

The rate-limiting, "pace-setting" enzyme of glycolysis that is inhibited by $ATP$ and activated by $ADP/AMP$.

Fermentation

An anaerobic pathway whose primary purpose is to regenerate $NAD+$ from $NADH$ to allow glycolysis to continue.

Pyruvate Oxidation

The conversion of pyruvate into acetyl-CoA in the mitochondria, releasing $CO_2$ and producing $NADH$.

Krebs Cycle (Citric Acid Cycle)

A circular pathway in the mitochondrial matrix that oxidizes acetyl-CoA into $CO_2$, producing $3\,NADH$, $1\,FADH_2$, and $1\,ATP/GTP$ per turn.

Chemiosmosis

The flow of $H^+$ ions back through $ATP$ synthase to generate $ATP$, powered by the proton gradient created by the Electron Transport Chain.

Oxygen (in Cellular Respiration)

The final electron acceptor in the electron transport chain; without it, $NADH$ accumulates and $ATP$ production collapses.

Alveoli

Lung structures with a huge surface area and thin gas exchange barriers ($0.2-0.3\,\mu m$) that facilitate rapid diffusion.

Ventilation Equation

$V = V_T \times f$, where $V_T$ is tidal volume and $f$ is breathing frequency.

Chemoreceptors

Sensors in the medulla and pons that detect low $O_2$, high $CO_2$, and high $H^+$ to regulate breathing.

$$CO_2$$

The main driver and strongest stimulus for breathing because it strongly affects blood $pH$.

Arteries

Blood vessels that carry blood away from the heart; though they often carry oxygenated blood, the pulmonary arteries carry deoxygenated blood.

Cardiac Output Equation

$CO = HR \times SV$, where $HR$ is heart rate and $SV$ is stroke volume.

Baroreceptors

Sensors in the carotid sinus and aortic arch that detect blood pressure and trigger negative feedback to return it to normal.

Cooperativity

A property of hemoglobin where the binding of one $O_2$ increases the affinity for additional $O_2$ molecules, producing a sigmoidal curve.

Bohr Effect

The phenomenon where high $CO_2$ and low $pH$ (acidic conditions) cause hemoglobin to release oxygen more easily.