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Cardiac Cycle (Part 4 of 4)

By: Administrator, Views: 10871

Diastole and systole are two phases of the cardiac cycle. They occur as the heart beats, pumping blood through a system of blood vessels that carry blood to every part of the body. Systole occurs when the heart contracts to pump blood out, and diastole occurs when the heart relaxes after contract...

Coaductile pathway, Timing of contraction signal & Conduction system and ECG

By: HWC, Views: 7926

• When the system is healthy, the signal to contract the entire conduction system originates in the SA node - known as the heart's pacemaker. • The SA node triggers contraction because it depolarizes at a faster rate than other parts of the conduction system. • The wave of excitation fr...

The primary factors that affect circulation - MABP, CO and SVR

By: HWC, Views: 8047

Introduction Blood flow is determined by the relative intensities of factors that drive and resist moving blood. • Cardiac output (CO) equals the mean arterial blood pressure (MABP, a driving force) divided by systemic vascular resistance (SVR, a resisting force). • Hormones and the cen...

Causes of Angina

By: Administrator, Views: 11138

Angina is a type of chest pain caused by reduced blood flow to the heart. Angina (an-JIE-nuh or AN-juh-nuh) is a symptom of coronary artery disease. Angina, which may also be called angina pectoris, is often described as squeezing, pressure, heaviness, tightness or pain in your chest.

Electrical changes in the heart

By: HWC, Views: 7564

• ECG: Graph of the voltage changes that occur during the cardiac cycle. • Readings are taken by electrodes placed on the surface of the body. • Electrodes detect voltage changes caused by the electrical activity of the heart. • P wave = atrial excitation (atrial depolarization). ...

Automated external defibrillator (AED)

By: Administrator, Views: 10785

An automated external defibrillator (AED) is a portable electronic device that automatically diagnoses the life-threatening cardiac arrhythmias of ventricular fibrillation and pulseless ventricular tachycardia, and is able to treat them through defibrillation, the application of electricity which...

Blood Pressure Measurement

By: Administrator, Views: 10650

How nurses check a patient's blood pressure. Blood Pressure The pressure exerted by the blood on the walls of the arteries. Higher (systolic) number: the pressure while the heart contracts. Lower (diastolic) number: the pressure when the heart relaxes between beats. Measured by a sphygmoma...

The Hypothalamus: The Body's Thermostat (Human Thermostat)

By: HWC, Views: 6957

Normal body function requires a relatively constant body temperature, which is regulated by the body's thermostat, a region of the brain called the hypothalamus. The hypothalamus generates a temperature set point for the body and appears to be the major site for the integration of temperature inf...

Anatomy and Chemical Makeup of a Single Hair (Animation)

By: HWC, Views: 5923

The hair's outer cuticle surrounds hair cells filled with tough keratin macrofibrils. Each macrofibril consists of smaller microfibrils. A microfibril is made up of three keratin polypeptide chains. The chains are linked together by disulfide bonds. A hair consists of keratin chains held...