BIOL 204 Week 5 Lab Electrocardiography Heart Sounds

BIOL 204 – Week 5 Lab Electrocardiography Heart Sounds Blood Pressure

Objective 1 ECG An electrocardiogram is a graphical recording of the hearts electrical changes during a cardiac cycle (heart beat) - Electrical changes initiated and propagated through the myocardium by specialized cells of the heart’s intrinsic conduction system Structures of the Intrinsic Conduction System Voltage changes seen

The voltage changes are recorded by leads which can be placed in different locations on the body We will use limb leads, placed on the appendages to record ECGs in this lab Lead 1: RA -, LA + most sensitive to electrical activity spreading horizontally across the heart Lead 2 RA -, LL + most sensitive to electrical activity spreading vertically (from the base to the apex) Lead 3 LA -. LL + also records electrical activity spreading from the base to the apex, but from a different orientation

When an ECG tracing is recorded using these lead combinations, a series of wave forms are generated which respond to the spread of electricity through the heart after it originates at the SA node

A typical ECG tracing

Y (vertical) axis measure voltage: - typically, 10 squares = 1 m. V X axis measures time: - At a chart speed of 25 mm/sec: each small block = 0. 04 sec and each large block (5 small blocks) = 5 X 0. 04 sec. = 0. 20 sec.

To determine the heart rate from an ECG tracing: Method #1: count the number of small squares from one R wave to the next R wave and divide that number into 1500 Method #2 Heart Rate (bpm) = 1500/#small squares locate an R wave on a bold line and identify the next R wave: HR = 72 bpm HR = 37 bpm

In this exercise you will evaluate a baseline ECG, and then identify and discuss changes in the ECG after a period of exercise and at rest

Objective 2 Heart Sounds In this lab activity you will record the ECG and heart sounds from a subject and, with the aid of an electronic stethoscope, hear those characteristic sounds of the heartbeat, typically described as a "lubdub. " Equipment Required PC Computer IWX/214 data acquisition unit USB cable IWX/214 power supply C-AAMI-504 ECG cable and electrode lead wires ES-100 electronic stethoscope Alcohol swabs; Disposable ECG electrodes

Heart Sounds Correlated with EKG

Objective 3 Arterial Blood Pressure http: //www. youtube. com/watch? v=UYc. Src. LVJHI

Here are the tools: A Stethoscope and a Sphygmomanometer.

Make sure you place the round end of the stethoscope 'under' the blood pressure cuff. You inflate the sphygmomanometer (blood pressure cuff) to a little above 180 mm Hg. This collapses the major arteries to the arm (that's why it is uncomfortable). Then you slowly release air by gently turning the air valve, and watch the pressure drop. When you first hear a sound, that will be the Systolic blood pressure. The sound you hear is the blood now flowing in the artery of the arm. This means that the systolic pressure is now greater than the pressure in the blood pressure cuff. As you continue to watch the pressure drop, when you no longer hear any sounds, that will be the Diastolic blood pressure.

Sounds of Korotkoff

Measuring Blood Pressure http: //www. youtube. com/watch? v=t. B 8 n. ISCEcs 8 – Tips http: //www. youtube. com/watch? v=8 e 6 qtn. Ha 8 ps – Inflating the blood pressure cuff http: //www. youtube. com/watch? v=Pr. RWk. Mo. FNRc&feature=Play. List&p=BAA 168 C 2 B 0 F 48 FED&index=0&playnext=1 –interpreting the values