Dive Synthesis

This lab investigated how differing conditions in water would affect the reflex known as the dive reflex, which was evaluated by measuring heart rate and amplitude of blood flow. The dive reflex is explained as a drop in heart rate and blood flow while the subject is submerged underwater. Bradycardia is the term used to describe the decreased heart rate (HR), and it is advantageous to mammals. Bradycardia helps retain as much oxygen as possible during the submersion in order for muscles to work more effectively. A normal heart rate is 60-100 beats per minute (BPM). Decreased blood flow (BF) is due to vasoconstriction (constriction of vessels) and this benefits mammals by regulating body temperature while underwater (thermoregulation). Thermoregulation

Furthermore, HR remained the same as the resting HR when the subject was submerged his face in warm water. BF increased (in amplitude) in the first two tests (BFbefore= 61mV, BFduring= 112mV; BFbefore=82mV, BFduring(cold)=93). When the subject submerged his arm under water, HR decreased and BF increased (BPMbefore= 66, BPMduring = 64; BFbefore = 145mV, BFduring= 200mV). These results show the dive reflex put into action. There are three requirements that need to be fulfilled in order for the dive reflex to occur: the water must be cold, the organism needs to be fully submerged (in this case, the face needs to be fully submerged), and the organism must be holding their breath. These were all verified in this experiment and thus the reflex occurred. This reflex is important in tetrapods, especially marine mammals, so that oxygen can be used in the muscles for longer periods of time as the organism is underwater. If oxygen is kept in the muscle tissue, the organism can cope with vasoconstriction as the dive reflex occurs. As stated above, this reflex occurs when two autonomic reflex pathways are