Structure Of Heart

The cardiac cycle refers to the repeating sequence of events that occur with each heartbeat, from the beginning of one heartbeat to the beginning of the next. The cardiac cycle involves both atrial and ventricular contraction (systole) followed by relaxation (diastole). There are three main stages: 1) atrial systole, where the atria contract; 2) ventricular systole, where the ventricles contract; and 3) complete cardiac diastole, where both the atria and ventricles relax. The cycle allows for blood to flow through the heart and into the arteries with each heartbeat.

The sinoatrial node, located in the wall of the right atrium, is the heart's natural pacemaker. It generates electrical impulses that pass through the heart and cause it to contract. The sinoatrial node initiates action potentials that travel through the conduction system to the atrioventricular node and then to the ventricles. As the primary pacemaker, the sinoatrial node controls the heart rate by regulating the firing of action potentials. Dysfunction or ischemia of the sinoatrial node can lead to irregular heart rhythms.

The cardiac cycle describes the sequence of events that occur with each heartbeat. It consists of systole, when the heart contracts and pumps blood, and diastole, when the heart relaxes and fills with blood. The cardiac cycle includes atrial and ventricular events. Atrial systole forces a small amount of blood into the ventricles, while atrial diastole allows the atria to fill with blood. Ventricular events include isovolumetric contraction, ejection of blood, isovolumetric relaxation, and rapid and slow filling as the ventricles refill with blood. The pressures and volumes in the heart chambers change throughout the cardiac cycle.

This document discusses cardiac output and its measurement. It defines cardiac output as the amount of blood ejected by each ventricle per minute, which is calculated as stroke volume multiplied by heart rate. It describes several methods to measure cardiac output, including the indicator dye dilution method, thermodilution, and measurement of inhaled inert gases. It discusses factors that can cause cardiac output to vary, such as age, sex, environmental temperature, exercise, and various pathological conditions.

HEART RATE REGULATION OF HEART RATE VASOMOTOR CENTER – CARDIAC CENTER MOTOR (EFFERENT) NERVE FIBERS TO HEART FACTORS AFFECTING VASOMOTOR CENTER for all medical & health care students

This document discusses the physiology of the heart. It begins by describing the different types of cardiac muscle and how cardiac muscle cells are interconnected. It then covers the cardiac cycle, including diastole and systole. Action potentials in cardiac muscle are longer than in skeletal muscle due to slow calcium channels. Contraction is triggered by calcium release from the sarcoplasmic reticulum and extracellular fluids. The heart pumps in two stages - the atria prime the ventricles, then the ventricles eject blood. Various waves in pressures, ECG, and sounds are related to the different cardiac cycle events.

DESCRIPTION ABOUT HEART ANATOMICAL STRUCTURES, FUNCTIONS OF HEART, PARTS OF HEART THEIR BASIC PATHWAYS FOR BLOOD CIRCULATIONS, TYPES OF PATHWAYS ALSO, ANATOMICAL PICTURE OF HEART.

The document provides an overview of cardiovascular physiology, including: - The cardiovascular system functions to circulate blood throughout the body, transporting oxygen, nutrients, hormones, and removing waste. - The heart is the central organ that pumps blood through two main circulations - pulmonary circulation to the lungs and systemic circulation to the rest of the body. - The functional anatomy of the heart includes four chambers, cardiac muscle tissue, valves that ensure one-way blood flow, and a conducting system that coordinates contractions.

Cardiac output refers to the volume of blood pumped by each ventricle per minute. It is determined by stroke volume, heart rate, preload, afterload, and peripheral resistance. Normal cardiac output is approximately 5 liters per minute. It can increase up to 600% in athletes due to enhanced cardiac reserve. Factors such as venous return, force of contraction, heart rate, and peripheral resistance maintain cardiac output within the body.