PA-CAT flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Brachial plexus roots

The brachial plexus begins from ventral rami C5 through T1; these roots give rise to trunks, divisions, cords, and terminal nerves supplying the upper limb.

Femoral triangle contents

From lateral to medial, the femoral triangle contains the femoral nerve, artery, vein, and lymphatics (empty space), bounded by the inguinal ligament, sartorius, and adductor longus.

Rotator cuff muscles

The rotator cuff comprises supraspinatus, infraspinatus, teres minor, and subscapularis; these muscles stabilize the humeral head within the glenoid during shoulder movement.

Diaphragm apertures

The diaphragm has three major apertures: caval hiatus at T8, esophageal hiatus at T10, and aortic hiatus at T12, transmitting the inferior vena cava, esophagus, and aorta.

Cardiac output equation

Cardiac output equals heart rate multiplied by stroke volume; it is also calculated by the Fick principle as oxygen consumption divided by arteriovenous oxygen difference.

Aldosterone action

Aldosterone acts on principal cells of the collecting duct, increasing sodium reabsorption and potassium secretion; water follows sodium, expanding extracellular fluid volume and raising blood pressure.

Oxygen-hemoglobin right shift

Increased carbon dioxide, hydrogen ions, temperature, and 2,3-BPG shift the oxygen-hemoglobin dissociation curve right, reducing hemoglobin oxygen affinity and enhancing oxygen unloading at tissues.

Glomerular filtration rate

GFR equals the filtration coefficient times net filtration pressure, driven by glomerular capillary pressure minus plasma oncotic and Bowman's capsule hydrostatic pressures; normal GFR is about 125 mL/min.

Michaelis-Menten equation

The Michaelis-Menten equation is v = Vmax[S]/(Km + [S]); Km is the substrate concentration at half-maximal velocity and reflects enzyme-substrate affinity inversely.

Competitive inhibition kinetics

A competitive inhibitor binds the enzyme active site reversibly, increasing apparent Km while leaving Vmax unchanged because high substrate can outcompete the inhibitor.

Glycolysis net products

Glycolysis converts one glucose into two pyruvate molecules, producing a net gain of two ATP and two NADH; phosphofructokinase-1 catalyzes the rate-limiting step.

Urea cycle rate-limiting enzyme

Carbamoyl phosphate synthetase I catalyzes the rate-limiting step of the urea cycle in liver mitochondria and is allosterically activated by N-acetylglutamate.

Na/K ATPase stoichiometry

The sodium-potassium ATPase pumps three sodium ions out of the cell and two potassium ions in per ATP hydrolyzed, maintaining the resting membrane potential.

Apoptosis intrinsic pathway

Cellular stress triggers mitochondrial cytochrome c release, which forms the apoptosome with Apaf-1 and activates caspase-9, leading to caspase-3 activation and programmed cell death.

Logistic growth equation

Logistic population growth is described by dN/dt = rN(1 - N/K), where r is intrinsic growth rate and K is carrying capacity; growth slows as population approaches K.

Endosymbiotic theory evidence

Mitochondria and chloroplasts have their own circular DNA, 70S ribosomes, and double membranes, supporting the theory that they originated from engulfed bacteria.

Gram stain mechanism

Gram-positive bacteria retain crystal violet because their thick peptidoglycan layer traps the dye; gram-negative bacteria decolorize and counterstain pink due to thin peptidoglycan and outer membrane.

Exotoxin versus endotoxin

Exotoxins are heat-labile proteins secreted by living bacteria and can be converted to toxoids; endotoxin is heat-stable lipopolysaccharide from gram-negative outer membranes that triggers fever and shock.

Beta-lactam mechanism

Beta-lactam antibiotics inhibit bacterial transpeptidases, blocking peptidoglycan cross-linking and causing cell lysis, especially in actively dividing gram-positive organisms.

Viral replication steps

Viral replication proceeds through attachment, penetration, uncoating, nucleic acid and protein synthesis, assembly, and release; viruses require host ribosomes because they lack their own.

Hardy-Weinberg equations

Hardy-Weinberg equilibrium uses p + q = 1 for allele frequencies and p² + 2pq + q² = 1 for genotype frequencies, assuming random mating, no mutation, migration, selection, or drift.

X-linked recessive pattern

X-linked recessive traits affect males more often, transmit from carrier mothers to sons, and show no male-to-male transmission because fathers pass only a Y chromosome to sons.

Frameshift mutation effect

A frameshift mutation inserts or deletes nucleotides not in multiples of three, shifting the reading frame and usually producing a truncated, nonfunctional protein more severe than a missense mutation.

Ideal gas law

The ideal gas law is PV = nRT, relating pressure, volume, moles, and absolute temperature; at STP one mole of ideal gas occupies about 22.4 liters.

Gibbs free energy spontaneity

Gibbs free energy is ΔG = ΔH - TΔS; a negative ΔG indicates a spontaneous process at constant temperature and pressure, while positive ΔG indicates nonspontaneous.

First-order half-life

For a first-order reaction, half-life equals ln(2)/k, approximately 0.693/k, and is independent of the initial reactant concentration.

SN2 reaction stereochemistry

SN2 is a concerted bimolecular substitution with backside nucleophilic attack, producing inversion of configuration; it is favored by methyl or primary substrates and polar aprotic solvents.

Hückel aromaticity rule

A cyclic, planar, fully conjugated molecule is aromatic if it contains 4n + 2 pi electrons; 4n pi electrons in the same system indicate antiaromaticity.

Markovnikov addition rule

In hydrohalogenation of an alkene, Markovnikov's rule places the hydrogen on the carbon with more hydrogens, forming the more stable carbocation intermediate; peroxides reverse regiochemistry with HBr.

Classical conditioning components

Classical conditioning pairs a neutral conditioned stimulus with an unconditioned stimulus that elicits an unconditioned response; repeated pairing makes the conditioned stimulus alone produce a conditioned response.

Negative reinforcement definition

Negative reinforcement increases a behavior by removing an aversive stimulus after the response, distinguishing it from punishment, which decreases behavior by adding or removing consequences.

General adaptation syndrome

Selye's general adaptation syndrome describes three stages of stress response: alarm with sympathetic activation, resistance with sustained cortisol, and exhaustion when resources deplete.