Question

Hey! I'm having trouble answering this for my assignment. Thank you so much in advance.

1) Which type of vessels, arteries or veins, has more muscle fibers? What is the functional significance of this?

2a) In general, we have no conscious control over smooth muscle or cardiac muscle function, whereas we can consciously control to some extent all skeletal muscles. Can you consciously control your breathing? What does this tell you about the muscle type of the diaphragm?

2b) What is a portal system? What organs does the hepatic portal system connect in adults? What is the purpose of this system?

2c) Starting with the umbilical vein, list/chart the general flow of blood through the fetus. What special features of the lung make it a useful organ for gas exchange?

Answer 1

Ams 1 - The arteries have higher smooth muscle in tunica media as compared to vein, hence the arterial wall is more thicker than vein, this is because arteries have to carry blood away from the heart to all the organ and tissue. Main function of vascular smooth muscle tone is to maintain caliber of blood vessels

Ans 2a.

The diaphragm is a domed sheet of skeletal muscle It serves two main functions:

1. Separates the thoracic cavity from the abdominal cavity.
2. It  is the primary muscle of respiration.

During inspiration, it contracts and flattens, increasing the vertical diameter of the thoracic cavity. This produces lung expansion, and air is drawn in.

During expiration, the diaphragm passively relaxes and returns to its original dome shape. This reduces the volume of the thoracic cavity.

Ans 2b Portal System

Portal circulation are connecting veins, which are additional network of vessels between arterial and venous circulation.

Function of the hepatic portal circulation is to route the venous blood (in this respect, deoxygenated blood) from the Gastro-intestinal tract through the liver, before mixing it with venous blood from the rest of the body through the inferior vena cava, this permitsliver to detoxify and process the substances entering the body from GI tract.

The system involves venous drainage from lower portion of the esophagus to the upper part of the anal, spleen and pancreas.

Ans 2c.