Award Date

1-1-1993

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

Number of Pages

82

Abstract

Recurring, brief fluctuations in lung pressure, refered to as Lung Pressure Transiets (LPTs), lasting approximately 5-6 seconds and with an amplitude of +0.25-2.0 mmHg were measured in nearly 30% of all voluntary dives in the aquatic turtle, Trachemys scripta elegans. LPTs were studied to determine if they could enhance pulmonary gas exchange. Skeletal muscle is the primary mechanism responsible for creating these pressure fluctuations, based on their persistence following inactivation or smooth muscle by atropine, a muscarinic blocking agent. Gas distribution experiments using helium injected into the lungs indicated that pulmonary gas distribution within a single lung and between lungs occurs nearly twice as rapidly in dives in which LPTs occur as in dives lacking LPTs. Collectively, these data indicate that LPTs reflect actual contraction of the lung(s) that lead to volume changes. Pulmonary gas exchange during diving is enhanced by LPTs due to stirring of stagnant pockets of lung gas and by the disruption of boundary layers present adjacent to respiratory gas exchange surfaces.

Keywords

Diving; Elegans; Fluctuations; Function; Lungs; Mechanism; Occurring; Pressure; Pseudemys; Scripta; Trachemys; Transient; Turtle

Controlled Subject

Biology; Physiology

File Format

pdf

File Size

2580.48 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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