Blood vessels and their system MCQ - Practice Questions with Answers

Blood vessels 

• The four chambers of the heart are directly connected with the following major blood vessels

1. Systemic aorta or systemic arch -  It originates from the left ventricle and distributes oxygenated blood to various body parts except lungs.
2. Pulmonary trunk or pulmonary arch - It originates from the right ventricle and gets divided into two pulmonary arteries that carry deoxygenated blood to lungs
3. Superior vena cava or precaval - It brings deoxygenated blood from head and upper parts of the body into the right atrium 
4. Inferior vena cava or postcaval - It brings deoxygenated blood from the lower parts of the body into the right atrium
5. Pulmonary vein - These are four in number ( i.e. two from each lung) and bring oxygenated blood from the lungs to the left atrium 
6. Coronary veins or coronary sinus - These return deoxygenated blood from heart wall into the right atrium
 

Blood vessels and their system

• The study of vessels is called angiology.
• The blood vessels of a closed circulatory system are of following three types

Arteries

• These are elastic vessels that transport blood away from the heart 
• The largest artery of the body is aorta
• Aorta originates from the heart and branches out into smaller arteries.
• The smallest branches are called arterioles, which further branch off into capillaries
• Arteries carry oxygenated blood except Pulmonary artery and Umbilical artery

Veins

• These are non-elastic blood vessels that transport blood to the heart.
• The smallest veins in the body are called venules.
• These receive blood from the arteries via the capillaries
• Veins carry deoxygenated blood except Pulmonary vein and Umbilical vein

Capillaries

• These are extremely small vessels that are located within the tissues of the body that transport blood from the arteries to the veins.
• Capillaries were discovered by Malpighi in 1661
• The walls of capillaries are thin and consists of only a single layer of endothelium
• The walls of capillaries help to exchange oxygen, carbon dioxide, nutrients and waste

Structure of wall of blood vessels

• The wall of arteries and veins consists of following three layers

1. Tunica interna- It is the innermost layer consisting of an inner endothelium of long, thin cells of squamous epithelium resting on a basement membrane along with an outer elastic membrane of yellow elastic tissue 
2. Tunica media - It is the middle layer which mainly consists of smooth muscle fibres and elastic connective tissue. It is thicker in artery 
3. Tunica externa - It is the outermost layer which is formed of loose connective tissue with longitudinally arranged white and yellow fibres. It is also known as tunica adventitia

Differences between arteries and veins 

The differences between arteries and veins are as follows: