Biology Questions

The mammalian heartis called myogenic (myo = muscle, genie = originating from). It means the heart beat or the activities of the heart are auto regulated which originates from a muscle called nodal tissue.In the human heart,heartbeat originates and contraction is initiated by a special modified heart muscle known as sinoatrial node. It is located in the right atrium; while the QRS waves are the depolarisation of the ventricles, which initiates the ventricular contraction.The T-wave represents the repolarisation,that is, the return of the ventricles from excited tonormal state.Hepatic portal system is the unique vascular connection that exists between the digestive tract and liver. This vein carries blood from intestine to the liver.

At first, the intensity of the pain stimuli is sent through the nerve fibres to the brain parts that are limked with the pain perception such as anterior cingulate cortex.

Steroid hormones exert their action by entering the nucleus of a cell and initiating or altering the expression of a gene.

The movement of blood in the body is called blood flow. The blood flows through the vessels, tissues and organs. Blood flow to a tissue will increase if the level of carbon dioxide at the tissue increases.