Anatomy & Physiology Flashcards

The primary buffer system in human blood is:

Answer: Bicarbonate-carbonic acid buffer system

The bicarbonate-carbonic acid system is the most important extracellular buffer in blood, maintaining pH between 7.35–7.45 through the equilibrium between CO2, H2CO3, and HCO3-.

Normal blood pH is maintained between:

Answer: 7.35–7.45

The narrow normal arterial blood pH range of 7.35–7.45 is tightly regulated by respiratory and renal mechanisms; values outside this range indicate acidosis or alkalosis.

Which immunoglobulin class provides the first-line defense in mucosal immunity?

Answer: IgA

Secretory IgA is the predominant immunoglobulin in mucosal secretions (saliva, tears, breast milk, GI secretions), providing the first defense against pathogens at mucosal surfaces.

The hormone responsible for stimulating ovulation is:

Answer: LH (luteinizing hormone)

The LH surge triggers ovulation by causing the dominant follicle to rupture and release the mature oocyte, typically around day 14 of a 28-day cycle.

Troponin I is elevated in serum as a marker of:

Answer: Myocardial cell injury

Cardiac troponin I (cTnI) is released specifically from damaged myocardial cells and is the most sensitive and specific biomarker for acute myocardial infarction.

The Frank-Starling law of the heart states that:

Answer: Stroke volume increases with increased ventricular end-diastolic volume

The Frank-Starling law states that stroke volume increases as ventricular end-diastolic volume (preload) increases, because greater myocardial stretch leads to more forceful contraction.