Question

Which among the following is not found in mammals?
A) Hepatic portal system
B) Hypophyseal portal system
C) Renal portal system
D) Hepatic and hypophyseal portal system

Answer 1

Hint: Mammals are a higher class of organisms so they require different sets of mechanisms and arrangements for their circulatory system.
As we know that blood flows in a certain pattern and in veins or capillaries so, an arrangement in which blood is collected from one set of capillaries by a vessel to another set of capillaries is known as portal system.
There are three types of portal systems – hepatic portal system, hypophyseal portal system, renal portal system.

Complete answer:
Option A) Hepatic portal system- hepatic portal system is found in all vertebrates.
It is a system which comprises veins and a set of tributaries.
It basically carries deoxygenated blood to the liver which can be detoxified before returning to the heart.
It mainly targets organs or carry blood from the capillaries of organs like stomach, intestine, pancreas to liver capillaries.
Its main function is to direct blood from regions of the gastrointestinal tract between the esophagus and rectum. It collects venous blood from the lower esophagus, parts of the stomach like duodenum, jejunum, Ileum, colon, spleen.
So, option A is not correct.
Option B) Hypophyseal portal system- As we can know that hypophyseal portal system targets the hypothalamus gland.
Hypophyseal system is a system of blood vessels which connects the hypothalamus and the anterior region of the pituitary gland.
It is the microcirculation of blood vessels at the base of the brain.
Function of the system to exchange and transport the hormones between the hypothalamus and anterior pituitary gland. It allows communication between the two organs by means of hormonal signaling.
As we have discussed it is present in the brain of human beings so it's present in all mammals too.
So option B is not correct.
Option C) Renal portal system- renal portal system is a venous portal system which is present in all living vertebrates except mammals, hagfish and lampreys. Renal portal system consists of renal portal vein and capillary network.
The renal portal vein is developed from the posterior cardinal vein.
It brings out the venous blood from the kidney where it passes through a shunted capillary network and convoluted tubules. then the blood enters the posterior cardinal vein or posterior vena cava.
Renal system carries blood from kidney to heart in lower invertebrates. They perform a systemic circulation which helps in proper blood flow in the body.
So, option C is correct.
Option D) Hepatic and hypophyseal portal system- This option is inappropriate as both systems are different sets of systems.
Hepatic refers to liver that means blood which is transported to liver and gets detoxified and returned back to heart.
Hypophyseal as we know is a part of the endocrine gland hypothalamus carrying hormones to another gland through hormonal signaling.
The hypothalamus and pituitary gland connect and coordinate the messages of the endocrine and nervous system.
So, option D is not correct.

So option C) is the correct answer.

Note:
Portal system is an arrangement of system which helps in blood purification, hormones signaling, transportation of messages from different organs into the heart and parts of the brain. It regulates the mechanism of the body well. As we know, it carries venous blood to be filtered out in the kidney before moving back to the heart ; it also has sets of tributaries capillaries to distinguish the oxygenated and deoxygenated blood.