Neural, Muscular, Bioenergetics, and Cardiovascular Key Concepts

What is the resting membrane potential (RMP)?

-70 mV

What membrane potential is typically required to reach threshold?

Approximately -55 mV

Which ion is found in higher concentration inside a resting neuron?

Potassium (K⁺)

Which ion is found in higher concentration outside a resting neuron?

Sodium (Na⁺)

What pump maintains the resting membrane potential?

Sodium-potassium pump

What is depolarization?

The inside of the cell becomes less negative

What is hyperpolarization?

The inside of the cell becomes more negative

What is the all-or-none principle?

Once threshold is reached, a full action potential occurs

What is saltatory conduction?

Action potentials jump from node to node

What is the primary neurotransmitter at the neuromuscular junction?

Acetylcholine

What neurotransmitter is released by most sympathetic neurons?

Norepinephrine

What receptor detects muscle stretch?

Muscle spindle

What receptor detects muscle tension?

Golgi tendon organ

What surrounds an entire muscle?

Epimysium

What surrounds a fascicle?

Perimysium

What surrounds a muscle fiber?

Endomysium

What stores calcium in muscle fibers?

Sarcoplasmic reticulum

What carries action potentials deep into the muscle fiber?

T-tubules

What protein forms the thin filament?

Actin

What protein forms the thick filament?

Myosin

What protein covers the myosin-binding sites at rest?

Tropomyosin

What protein binds calcium?

Troponin

What protein acts like a spring within the sarcomere?

Titin

What is a motor unit?

One alpha motor neuron and all muscle fibers it innervates

What are the three energy systems?

ATP-PCr, Glycolytic, Oxidative

What is the fastest energy system?

ATP-PCr

How long does ATP-PCr predominate?

Approximately 3-15 seconds

How much ATP is produced from one phosphocreatine molecule?

1 ATP

What is the rate-limiting enzyme of ATP-PCr metabolism?

Creatine kinase

What is the rate-limiting enzyme of glycolysis?

Phosphofructokinase (PFK)

What is the rate-limiting enzyme of the Krebs cycle?

Isocitrate dehydrogenase

How much ATP does glycolysis produce from one glucose?

2 ATP

How much ATP does one glucose yield overall?

32 ATP

How many ATP come from NADH during glucose oxidation?

25 ATP

How many ATP come from FADH₂ during glucose oxidation?

3 ATP

Under what conditions is pyruvate converted to lactate?

Low oxygen availability

What is beta oxidation?

Conversion of free fatty acids into acetyl-CoA

What is the major fuel source for the brain?

Glucose

What energy source is used to resynthesize ATP immediately?

Phosphocreatine

What does direct calorimetry measure?

Heat production

What does indirect calorimetry measure?

Oxygen consumption and carbon dioxide production

What does VO₂ represent?

Volume of oxygen consumed per minute

What does VCO₂ represent?

Volume of carbon dioxide produced per minute

What does RER stand for?

Respiratory Exchange Ratio

What is the formula for RER?

VCO₂ ÷ VO₂

What RER indicates pure carbohydrate utilization?

1.0

What RER indicates pure fat utilization?

0.70

What does VO₂max represent?

Maximum oxygen uptake

What is EPOC?

Excess Postexercise Oxygen Consumption

Why does EPOC occur?

To restore ATP, PCr, oxygen stores, and convert lactate back to glycogen

What is lactate threshold?

The point where lactate production exceeds lactate clearance

What does SA node stand for?

Sinoatrial node

What is the pacemaker of the heart?

SA node

Why does the AV node delay conduction?

Allows the atria to contract before the ventricles

What neurotransmitter decreases heart rate?

Acetylcholine

What neurotransmitter increases heart rate?

Norepinephrine

What is stroke volume?

The volume of blood pumped per heartbeat

What is the formula for stroke volume?

EDV − ESV

What is cardiac output?

The volume of blood pumped per minute

What is the formula for cardiac output?

HR × SV

What is ejection fraction?

SV ÷ EDV

What does systolic blood pressure represent?

Pressure during ventricular contraction

What does diastolic blood pressure represent?

Pressure during ventricular relaxation

What does MAP stand for?

Mean Arterial Pressure

What is the primary site of resistance in the vasculature?

Arterioles

What does vasodilation do?

Increases blood flow

What does vasoconstriction do?

Decreases blood flow