Module 1 Lesson 1 Flashcards
Who discovered the importance of calcium in heart function in 1883?
Sidney Ringer
What is the formula for calculating cardiac output (CO)?
CO = Heart Rate (HR) × Stroke Volume (SV)
What is the typical resting cardiac output?
~5L/min
Name two types of calcium channels found in the heart.
L-type and T-type Ca²⁺ channels
What ion concentrations are present in one liter of lactated Ringer’s solution?
Na⁺ 130 mmol/L, Cl⁻ 109 mmol/L, Lactate 28 mmol/L, K⁺ 4 mmol/L, Ca²⁺ 1.5 mmol/L
What are the three functional states of voltage-activated ion channels?
Reprimed, Activated, Inactivated
What type of membrane proteins require ATP to move ions against a gradient?
Pumps, e.g., Na⁺-K⁺ pump, Ca²⁺ pump
Why is cardiac output the same for both the left and right ventricles?
Because blood must be evenly distributed through systemic and pulmonary circulation to maintain balance in oxygenation and perfusion.
How do ion channels differ from pumps and exchangers in their function?
Ion channels allow passive ion flow based on gradients
pumps use ATP to move ions against gradients
exchangers use one ion’s gradient to move another ion in exchange with no direct ATP
Why do skeletal muscles experience fatigue?
Fatigue can result from ion imbalance, ATP depletion, and metabolic byproducts affecting contraction efficiency.
What role does calcium play in excitation-contraction coupling in muscle cells?
Calcium binds to regulatory proteins, triggering actin-myosin interactions that produce contraction.
How does a voltage change lead to ion channel opening?
Voltage change moves charged residues in the channel (S4 region), leading to conformational change and channel opening.
Why does the Na⁺-Ca²⁺ exchanger not require ATP?
It uses the Na⁺ gradient to move Ca²⁺, relying on passive ion movement rather than energy-consuming transport.
A patient is experiencing hypertension. How would a calcium channel blocker like verapamil help?
Verapamil inhibits Ca²⁺ influx in heart and blood vessel cells, reducing contraction force and lowering blood pressure.
How would you determine if a sodium channel mutation affects cardiac excitability?
Measure gating current, voltage dependence, and ion conductance changes in mutated channels.
If a person has low calcium levels, what physiological effects might you expect in their muscle function?
Weak muscle contractions due to impaired excitation-contraction coupling.
If cardiac output increases to 30L/min during exercise, how would stroke volume and heart rate likely change?
Both stroke volume and heart rate would increase to achieve higher CO.
How would a defect in Na⁺-K⁺ pump function affect cardiac cells?
It would disrupt ion gradients, leading to abnormal excitability and contraction issues.
