06: The Circulatory System : Icse-x-biology

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#1-a
Endothelium
Ans : Endothelium- It is the innermost layer of the muscular wall of an artery or a vein which faces the lumen.

#1-b
Lymph nodes
Ans : Lymph nodes- The structures from which fresh lymph channels arise which pour the lymph into major anterior veins.

#1-c
Venule
Ans : Venule- The smallest common blood vessel formed by the union of capillaries.

Describe the structural differences between an artery and a vein

Ans :

Artery	Vein
An artery is a vessel which carries blood away from the heart towards any organ.	A vein is a vessel which conveys the blood away from an organ towards the heart.
Artery has thick muscular walls.	Vein has thin muscular walls.
It has narrow lumen.	It has a broad lumen.
There are no valves.	Thin pocket-shaped valves are present in the veins.
Arteries progressively decrease in size and branch to form arterioles. Arterioles further breaks up to form capillaries.	Capillaries unite to form branches called Venules. Venules further unite to form veins.

Qstn #3
What are the functions of tonsils and spleen?
Ans : Tonsils: Tonsils are lymph glands located on the sides of the neck. They tend to localize the infection and prevent it from spreading it in the body as a whole.
Spleen: The spleen is a large lymphatic organ. The spleen acts as a blood reservoir in case of emergency such as haemorrhage, stress or poisoning. It produces lymphocytes and destroys worn out RBCs.

#4-a
The left ventricle has thicker walls than the right ventricle.
Ans : The left ventricle pumps blood to the farthest points in the body such as the feet, the toes and the brain against the gravity while the right ventricle pumps the blood only up to the lungs. Therefore, the left ventricle has thicker walls than the right ventricle.

#4-b
The walls of the right ventricle are thicker than those of the right auricle.
Ans : The right ventricle pumps blood to the lungs for oxygenation whereas the right auricle receives the blood from vena cavae and passes it to the right ventricle. Therefore, walls of the right ventricle are thicker than those of the right auricle.

#5-a
The walls of the left ventricle are thicker than the walls of all other chambers.
Ans : The left ventricle pumps blood to the farthest points in the body such as the feet, the toes and the brain against the gravity. Thus, it requires greater force to push the blood. In order to with stand with the force applied the walls of the left ventricle are thicker than the walls of all the chambers.

#5-b
Blood flowing away from the stomach and intestines is put into circulation via the liver and not directly
Ans : The blood from stomach and intestines enters the liver via hepatic portal vein because the liver monitors all the substances that have to be circulated in body. The excess nutrients such as glucose, fats are stores in the liver. Excess amino acids are broken down by the process deamination. Toxic substances are detoxified.