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Candidate Name Candidate Number

IB Biology Lab Cover Sheet

Title: Heart Rate Design Lab

Check Required Criteria for Lab

D_____DCP ______ CE_______

DESIGN

ASPECT 1: DEFINING THE PROBLEM AND SELECTING VARIABLES
Background Information: The heart is a vital organ made of cardiac muscle that pumps blood throughout the body. Heart rate is associated with the contraction of the different chambers of the heart, and is considered myogenic. As a result, the heart beat is controlled independently of the central nervous system and is instead controlled by the pacemaker, also known as the Sino arterial node. The node sends signals through nerves in the heart to other nodes such as the AV or atrio-ventricular node and these result in the contraction of the chambers (Copeland, 1991). Heart rate is the number of heart beats per unit of time, typically expressed in beats per minute or bpm. The average heart rate at rest under normal conditions of adolescents and adults is 63.3 bpm ± 13.1 bpm, with variability of 3.2 bpm ± 2.1 (Leschka, 2006). Other factors also have an influence on the heart beat and heart rate such as the medulla of the brain of the hormone adrenaline.
External stimuli or external factors also result in alterations of the heart rate. These include physical and emotional factors. One type of external stimuli that is shown to have effects on the heart rate is sound, specifically music. Music is currently being considered to be used as therapy for coronary conditions as well as on anxiety (Smolen et al, 2002). In addition, music is widely prevalent in the lives of adolescents. Teenagers in this day are age are exposed to music on a regular basis and a majority of adolescents living in the United States own mp3 or I-Pods (Epperson, 2011).
Sound has been shown to have effects on the heart rate. The