BIOL 251 Unit Exam 2 Part 1 | Portage Learning A&P II | Blood Vessels & Immune System | 100% Correct Q&A | Updated 2026

Ace your second assessment with this verified BIOL 251 Unit Exam 2 solution guide, specifically tailored for Portage Learning’s Anatomy & Physiology II. This document contains 100% correct answers for 25+ high-yield questions covering Chapter 20 (Blood Vessels & Circulation) and Chapter 21 (The Lymphatic System & Immunity). The Blood Vessel section provides clear answers on the three tunics (Externa, Media, and Intima), the sequence of systemic circulation, and the mechanics of Cardiac Output (CO) and Pulse Pressure. It also details specific capillary structures, including fenestrated, continuous, and sinusoid capillaries, and the role of precapillary sphincters in controlling blood flow. The Immunity section is a "must-study" for nursing students, breaking down Humoral Immunity (B-cells) versus Cellular Immunity (T-cells). It includes critical data on antibody classes (specifically IgG crossing the placenta and IgD on B-cells) and the differences between Active/Passive Natural and Artificial Immunity.