NU 545 Unit 5 Study Guide (PDF) | (2026/2027) | Advanced Pathophysiology | University of South Alabama

NU 545
Unit 5 Study Guide
Advanced Pathophysiology
University of South Alabama.

This document provides a focused
study guide
It summarizes key concepts, lecture highlights, and
exam-relevant material to support efficient last-minute
review. The guide is structured to help students
reinforce understanding, identify weak areas, and prepare
confidently for the assessment.

, 1




UNIT 5: RESPIRATORY AND RENAL SYSTEMS




Physio-Pathological Basis of Advanced Nursing (NU 545)

Study Guide and Resources: Chapters 34 – 39




Edited by: Jessica L. Santos




1

, 2




SECTION 1: STUDY GUIDE

1. KNOW TYPE I AND TYPE II ALVEOLAR CELLS. (p. 1229; key search term: “lipoprotein
that coats”)
 Bronchioles subdivide to form tiny tubes called alveolar ducts that end in
clusters of alveoli called alveolar sacs.
 Alveoli are the primary gas-exchange units of the lung,
where O2 enters the blood and CO2 is removed.
 Tiny passages called pores of Kohn permit some air to pass through the
septa from alveolus to alveolus, promoting collateral ventilation and even
distribution of air among the alveoli.
 At birth, there are 50 million alveoli, by adulthood you have 480
million.
 The alveolar septa (what separates each alveoli sac) has 2
layers (there is NO muscle layer)
─ Epithelial layer
─ Thin elastic basement membrane
 Two major types of epithelial cells appear in the alveolus:
─ Type I alveolar cells: provide structure
─ Type II alveolar cells: (or “pneumonocytes”) secrete
surfactant (lipid protein that coats the inner surface of the
alveolus and facilitates its expansion during
inspiration, lowers alveolar surface
tension at end expiration, thus
preventing lung collapse)
 Alveoli contain cellular components of
inflammation and immunity, particularly the mononuclear phagocytes.
─ Called alveolar macrophages
─ Ingest foreign material that reaches the alveolus and prepares it for removal
through lymphatics.




2

, 3

2. ROLE OF SURFACTANT IN THE LUNGS (INFANTS AND ADULTS). (pp. 1229, 1235,
1256, and 1292; key search term: “lipoprotein that coats” and “ventilation or
distention”)
Surfactant (p. 1229)
 Secreted by Type II alveolar pneumonocyte cells.
 Is a lipid protein that coats the inner surface of the alveolus and facilitates its expansion
during inspiration, lowers alveolar surface tension at end expiration, preventing lung
collapse.
 Contributes to control of lung inflammation, and innate and adaptive immunity.
Surfactant (p. 1235)
 Allows alveolar ventilation/distention to be possible- it lowers the surface tension by
coating the air liquid interface in the alveoli.
 Surfactant is a lipoprotein (90% lipids, 10% protein)
 There are 2 groups of surfactant proteins:
─ Group (SP-B and SP-C)
 Consists of small hydrophobic molecules
 Detergent like affect that separates liquid molecules = ↓surface tension
─ Group (SP-A and SP-D)
 Consist of large hydrophobic molecules called collectins (pattern recognition
molecules)
 Capable of inhibiting foreign pathogens
 Surfactant lines the alveolar side of the alveolocapillary membrane and REVERSES
Laplace's law (where the pressure, P, required to inflate a sphere is = to 2x the surface
tension (ST) divided by the radius (R) of the sphere, or P= 2T/r)
 As the radius of a surfactant lined sphere grows smaller (alveolus), the surface tension
DECREASES, and as the radius grows larger, the surface tension INCREASES.
 This occurs because the surfactant
molecules have much weaker
intermolecular attraction compared
with the liquid molecules.
 The surfactant molecules occupy most
of the air fluid interface and disrupt the
intramolecular forces that tend to
collapse the alveoli.
 The alveoli are much easier to inflate at
low lung volumes (after expiration) than
at high volumes (after inspiration).
 The decreased surface tension = alveoli
free of fluid.
 Surfactant production disrupted or not
produced = ↑ surface tension =
alveolar collapse, ↓ lung expansion, ↑
work of breathing, and severe gas
exchange abnormalities.
 Absence of surfactant = surface tension
tends to attract fluid into the alveoli.
 Surfactant participates in host defense
against respiratory pathogens.
Surfactant Impairment (p. 1256)
 Surfactant impairment results from decreased production or inactivation of surfactant,
which is necessary to reduce surface tension in the alveoli and thus prevent lung collapse

3