Question

1. Explain the full mechanism by which our heart pumps blood to the rest of the body including the specific role of phosphatidylinositol plays in calcium sequestration, starting from a signaling molecule. Keep in mind that the heart is a muscle which contracts and relaxes. (10-points)

Answer 1

MECHANISM BY WHICH HEART PUMPS BLOOD TO THE REST OF BODY.

The heart is at the center of circulatory system, which is a network of blood vessels that delivers blood to every part of your body. Blood carries oxygen and other important nutrients that all body organs need to stay healthy and to work properly.Your heart is a muscle, and its job is to pump blood throughout your circulatory system.

Your heart is divided into two separate pumping systems, the right side and the left side.

• The right side of your heart receives oxygen-poor blood from your veins and pumps it to your lungs, where it picks up oxygen and gets rid of carbon dioxide.
• The left side of your heart receives oxygen-rich blood from your lungs and pumps it through your arteries to the rest of your body.

Your heart has four separate chambers that pump blood, two on the right side and two on the left.

The heart has four chambers: two atria and two ventricles.

• The right atrium receives oxygen-poor blood from the body and pumps it to the right ventricle.
• The right ventricle pumps the oxygen-poor blood to the lungs.
• The left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle.
• The left ventricle pumps the oxygen-rich blood to the body

Blood flows through your heart and lungs in four steps:

1. The right atrium receives oxygen-poor blood from the body and pumps it to the right ventricle through the tricuspid valve.
2. The right ventricle pumps the oxygen-poor blood to the lungs through the pulmonary valve.
3. The left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle through the mitral valve.
4. The left ventricle pumps the oxygen-rich blood through the aortic valve out to the rest of the body.

The left and right atria are smaller chambers that pump blood into the ventricles. The left and right ventricles are stronger pumps. The left ventricle is the strongest because it has to pump blood out to the entire body. When your heart functions normally, all four chambers work together in a continuous and coordinated effort to keep oxygen-rich blood circulating throughout your body. Your heart has its own electrical system that coordinates the work of the heart chambers (heart rhythm) and also controls the frequency of beats (heart rate).

Role of phosphatidylinositol plays in calcium sequestration

The inositol phospholipids form the structural basis for a complex interplay of signalling responses initiated, most commonly, by receptor activation and resulting in changes in Ca2+, protein kinase cascades, and ion channel/exchanger activity. Phosphatidylinositol (PI) itself is a minor phospholipid constituent of all eukaryote plasma membranes. PI is unusual in that it is phosphorylated, most commonly first on the 4- and then on the 5-position to generate PI(4,5)bisphosphate (PIP2), the central player in inositide signalling3,4. Phosphoinositide-derived second messengers regulate responses ranging from immediate changes in vascular tone and hormone secretion to more prolonged responses such as cell growth and differentiation that require transcriptional changes. This wide range of downstream responses is made possible, in part, by the multiple signalling molecules generated from phosphoinositides.5–9