Body Fluids and Circulation Test - 26

Generally, the capillaries join together to form a vein. The hepatic portal vein carries blood from the spleen and intestines into the liver. The veins from the spleen and intestines break into capillaries before entering the liver as the hepatic portal vein.

• Humans have double circulation. The blood pumped by the right ventricle enters the pulmonary artery, whereas the left ventricle pumps blood into the aorta.
• The deoxygenated blood pumped into the pulmonary artery is passed onto the lungs from where the oxygenated blood is carried by the pulmonary veins into the left atrium.
• This pathway constitutes the pulmonary circulation.
• The oxygenated blood entering the aorta is carried by a network of arteries, arterioles, and capillaries to the tissues from where the deoxygenated blood is collected by a system of venules, veins, and vena cava and emptied into the right atrium. This is the systemic circulation. 
  Hence, the correct option is C.

The fetal circulation works differently from that of an adult, mainly because the lungs are not in use in fetal circulation. Lungs are bypassed in fetal circulation. A hole in the septum called the foramen ovale, allows blood from the right atrium to enter the left atrium during fetal development. This opening allows blood to bypass the nonfunctional fetal lungs while the fetus obtains its oxygen and nutrients from the mother through the placenta and the umbilical cord. A layer of tissue called the septum primum acts as a valve over the foramen ovale during fetal development. After birth, the pressure in the right side of the heart drops as the lungs open and begin working, causing the foramen ovale to close entirely.

During the cardiac cycle in humans, the blood pumped by the right ventricle enters the pulmonary artery, whereas the left ventricle pumps blood into the aorta. The deoxygenated blood pumped into the pulmonary artery is passed onto the lungs from where the oxygenated blood is carried by the pulmonary veins into the left atrium. This pathway constitutes the pulmonary circulation. The pulmonary vein carries most oxygenated blood in the body. 

Electro-cardiograph is a machine used to obtain an electrocardiogram (ECG). ECG is a graphical representation of the electrical activity (difference in electric potential) of the heart during a cardiac cycle. To obtain a standard ECG, a patient is connected to the machine with three electrical leads (one to each wrist and to the left ankle) that continuously monitor the heart activity. For a detailed evaluation of the hearts function, multiple leads are attached to the chest region.

Atrial diastole is characterized by the relaxation of the atrial muscles. During this stage, the blood enters into the atria, as the volume of the blood in the atria increases the pressure within it decreases.

The hepatic portal system includes the veins that drain blood from capillaries in the spleen, stomach, pancreas, and intestine. Instead of emptying their blood directly into the inferior vena cava, they deliver it by way of the hepatic portal vein to the liver. Upon entering the liver, the portal vein divides and sub-divides into ever smaller branches. Eventually, the portal blood flows into a vast network of sinus like vessels called sinusoids. These are enlarged capillaries that serve as blood channels within the tissues of the liver, spleen, thyroid gland, and other structures. After leaving the sinusoids, blood is finally collected by the hepatic veins, which empty into the inferior vena cava. 

In all the parts of the circulation, venous blood passes from the tissues to the heart by the most direct route through only one capillary bed. In the (hepatic) portal circulation of man, venous blood passes from the capillary beds of the abdominal part of the digestive system, the spleen, and pancreas to the liver. It passes through a second capillary bed, the hepatic sinusoids, in the liver before entering the general circulation via the inferior vena cava (IVC). In this way, blood with a high concentration of nutrients, absorbed from the stomach and intestines, goes to the liver first. In the liver, certain modifications take place, including the regulation of nutrient supply to other parts of the body.

William Harvey was an English physician. He was the first known to describe completely and in detail the systemic circulation and properties of blood being pumped to the brain and body by the heart. 

A.Correct option - A
B.Explanation for correct option -A

• Platelets are tiny cell fragments that are found within our blood.
• The primary responsibility of the platelets is to stop the bleeding when there is an injury to the body.
• A barrier called a blood clot must be formed to seal the wound.
• Just like a leaking pipe must be plugged, a damaged blood vessel must be blocked so that there is no excessive blood loss.