Structure of mammalian heart, cardiac cycle, ECG, blood pressure and its regulation?

The structure of the mammalian heart consists of four chambers: two atria and two ventricles. The atria are the upper chambers that receive blood from the body and lungs, while the ventricles are the lower chambers responsible for pumping blood out of the heart.

The cardiac cycle refers to the sequence of events that occur during one complete heartbeat. It consists of two phases: diastole and systole. During diastole, the heart is relaxed, and blood fills the atria and ventricles. During systole, the heart contracts, and blood is pumped out of the ventricles.

The electrical activity of the heart is measured using an electrocardiogram (ECG). An ECG records the electrical signals generated by the heart as it contracts and relaxes. It consists of several waves, including the P wave (atrial depolarization), QRS complex (ventricular depolarization), and T wave (ventricular repolarization).

Blood pressure is the force exerted by the blood against the walls of the blood vessels. It is measured using two values: systolic pressure (the pressure when the heart contracts) and diastolic pressure (the pressure when the heart is at rest). Blood pressure is regulated by various mechanisms, including the autonomic nervous system, hormones (such as adrenaline and aldosterone), and the renin-angiotensin-aldosterone system. These mechanisms help maintain blood pressure within a normal range to ensure adequate blood flow to the body's tissues.