Portal Systems in Humans

I was reading about nephrons in my physiology book when i came across this-

The efferent arterioles and peritubular capillaries technically constitute a portal system

But according to Wikipedia, renal portal system is absent in mammals. Can someone please explain this contradiction?

Edit 1: Could it be that humans are an exception to the case and do contain a renal portal system?

Edit 2: When we were discussing this in class, the my lecturer did say, "They are like portal sytems."

Why is human renal portal system not considered a portal system? Although, it connects two capillary beds (efferent arterioles and peritubular capillaries)

Edit 3- Some sites do say that the capillary beds that connect generally belong to different organs. Could this be responsible for exclusion of human renal portal sytem?

Complex systems biology

Complex systems theory is concerned with identifying and characterizing common design elements that are observed across diverse natural, technological and social complex systems. Systems biology, a more holistic approach to study molecules and cells in biology, has advanced rapidly in the past two decades. However, not much appreciation has been granted to the realization that the human cell is an exemplary complex system. Here, I outline general design principles identified in many complex systems, and then describe the human cell as a prototypical complex system. Considering concepts of complex systems theory in systems biology can illuminate our overall understanding of normal cell physiology and the alterations that lead to human disease.

Keywords: agents complexity evolution.

Conflict of interest statement

I declare I have no competing interests.


Examples of complex environments: flock…

Examples of complex environments: flock of birds, beehive, social networks, cities and states.…

Portal system

2. an organized set of principles or ideas. adj., adj systemat´ic, system´ic.

The parts of a system can be referred to as its elements or components the environment of the system is defined as all of the factors that affect the system and are affected by it. A living system is capable of taking in matter, energy, and information from its environment (input), processing them in some way, and returning matter, energy, and information to its environment as output.

An open system is one in which there is an exchange of matter, energy, and information with the environment in a closed system there is no such exchange. A living system cannot survive without this exchange, but in order to survive it must maintain pattern and organization in the midst of constant change. Control of self-regulation of an open system is achieved by dynamic interactions among its elements or components. The result of self-regulation is referred to as the steady state that is, a state of equilibrium. homeostasis is an assemblage of organic regulations that act to maintain steady states of a living organism.

A system can be divided hierarchically into subsystems, which can be further subdivided into sub-subsystems and components. A system and its environment could be considered as a unified whole for purposes of study, or a subsystem could be studied as a system. For example, the collection of glands in the endocrine system can be thought of as a system, each endocrine gland could be viewed as a system, or even specific cells of a single gland could be studied as a system. It is also possible to think of the human body as a living system and the endocrine system as a subsystem. The division of a system into a subsystem and its environment is dependent on the perspective chosen by the person studying a particular phenomenon.

Organ systems of human body and their functions – 11

The human body consists of different complex organs which are also subdivided into smaller units and into specific body parts. No matter how small or large each part may be, they work together as one and enable a human to live in full potential.

Circulatory System

The circulatory system works as a transporter of nutrients and gasses all over the body and into each tissue fiber, down to each cell. The distribution of nutrients gasses are made possible by blood which circulates in every part of the body.


  • Cardiovascular system: made up of heart, blood and blood vessels. The main worker of this subdivision is the heart. The heart enables blood to be circulated thru blood vessels throughout the whole body.
  • Lymphatic system: made up of lymph vessels, lymph nodes, tonsils, spleen and thymus. The main work of this subdivision is to produce and disseminate lymphocytes, which are immune cells through connection of arteries and veins.

Digestive System

The digestive system primarily consists of mouth, stomach, the small and large intestines and rectum. On the other hand, accessory organs such as teeth, tongue, liver and pancreas assist the primary organs to make the breakdown of food easy and manageable.

This digestive system makes the food we eat to be substances which nourish and activate our body in the form of energy. Enzymes and digestive juices play the vital role of converting fats, proteins and carbohydrates into energy that our body uses every day.

Endocrine System

The endocrine system plays the big role in physical growth, homeostasis, metabolism and sexual development of the human anatomy. The system exudes and handles hormones and hormonal function. The main parts include: pituitary gland, pineal gland, thyroid gland, thymus, ovaries (women) and testes (men).

Integumentary System

The integumentary system which involves the skin, nails, hair and sweat glands, secure internal organs from harm or injury. Furthermore, it averts dehydration, stores fat and makes vitamins for the body.

Muscular System

The muscular system is all about muscle tissues and helps the whole body to be flexible in movements.

Nervous System

The nervous system serves as the nexus of control for the whole human anatomy. It does the coordination and monitoring of internal organs to suit the external surroundings. The system is made up of the brain, spinal cord and the nerves.

Reproductive System

The reproductive system allows humans to produce their offspring through sexual intercourse, and ensures sex cell production until the development of progeny.

  • Male reproductive organs: testes, scrotum, penis and prostate
  • Female reproductive organs: vagina, ovary, uterus and mammary glands

Respiratory System

The respiratory system allows oxygen to enter the body. This is made possible through breathing or inhaling. The nose, larynx, trachea, diaphragm, bronchi, and lungs are the main organs that make up the respiratory system.

Urinary/ Excretory System

The urinary or excretory system filters and discharges excess fluid or other harmful substance streamed through the blood. The kidneys, urethra and bladders are the main organs within this system.

Skeletal System

The skeletal system is the framework of our body. Meaning it gives form and shape while letting body to move freely. It also protects our body, and mainly the internal organs from injuries. It helps the body to store minerals and produce blood cells. This system is made up of bones, cartilages and joints.


The splenic vein is responsible for blood flow from the spleen while the superior mesenteric vein is responsible for the blood flow coming from the small intestine and is remarkably high in nutrients. Three tributaries which meet with the splenic vein, the inferior mesenteric vein, the pancreatic vein, and the gastroepiploic vein, engorges the splenic vein to several times the original necessary size. The stomach drains into the left gastroepiploic vein.

The pancreas drains into the pancreatic vein. Finally, the inferior mesenteric vein is responsible for the blood flow out of the large intestine. The superior mesenteric vein receives the blood flow from the right gastroepiploic vein which is responsible for providing additional drainage to the stomach.

The hepatic vein receives three additional veins. Included would be the left and right gastric veins and the veins from the gallbladder. The gastric veins provide drainage for the lesser curvature of the stomach and the gallbladder is drained by the cystic vein.

Humans Vs. Rats

The overall digestive tract is very similar anatomically in rats and humans. The major difference is that rats lack a gall bladder. Instead, their bile, bodily fluid that breaks down lipids, flows directly from the liver to the small intestines. Rats also lack the ability to regurgitate due to the build of their esophagus and stomachs. The rat digestive tract is noticeably shorter than the human digestive tract. Rats do not have an appendix at the end of the caecum like humans do.

The general structure of the respiratory system in Homo sapiens and Rattus norvegicus is similar. The rat’s respiratory system is significantly smaller in size. Both humans and rats inhale oxygen and exhale carbon dioxide, like other animals. A two-part respiratory system, upper and lower, exists in both. However, in humans, the right lung has three lobes, and the left lung has two lobes. In rats, the left lung has two lobes, and the right lung has four lobes. Rats also able to take more breaths in a minute.

Both Homo sapiens and Rattus norvegicus circulate their blood through a closed circulatory system called the cardiovascular system. Both have a four-chambered heart, seeing as they are both mammals. Both use blood to transport nutrients, wastes, water, oxygen, and carbon dioxide throughout the body. The rat’s circulatory system is smaller in size. Rat has a caudal artery that brings blood to the tail. This is absent in humans.

The urinary system within humans and rats is very similar in structure and function. It is responsible for processing the waste products of metabolism. The major organs and parts that make up the urinary system in both humans and rats include the kidneys, ureter, urinary bladder, and urethra. Also, humans and rats are two examples of how waste removal is a crucial part in maintaining homeostasis. In humans and rats, the first thing that happens in the urinary system is blood enters the kidneys through the renal artery and exits through the renal vein. As the blood passes through the kidneys, millions of nephrons or excretory tubules within the kidneys filter out blood plasma, nitrogenous wastes, urea, salts, ions, glucose, and amino acids. Then the nephrons reabsorb the substances needed by the body from the filtrate and return them to the blood. Then the waste fluid, urine, leaves the kidneys through the ureter which drains into the urinary bladder where it is temporarily stored. From there, the urine passes through a tube called the urethra and exits the body during urination. The urinary system of a rat and a human is almost identical. The only major difference is the size of the organs between that of a human and that of a rat.

In female humans and rats, the main organs that compose their reproductive system consist of the ovaries, oviducts, uterus, and vagina. A difference between female rats and humans is that a rat’s vagina connects to the urogenital aperture and humans do not have a urogenital aperture. The vagina is a short, muscular canal located below the urethra. Also, the rat’s vagina is much shorter in length than the human vagina. In female rats, the ovaries which produce egg cells (ova) and female hormones (estrogen and progesterone), are small and located just below the kidneys inside the peritoneal membrane. Also, the shape of the uterus in rats is different than in humans. In rats it is Y-shaped and in humans it’s a pear shaped organ. Furthermore, rats do not undergo menstruation such as humans do. Instead, in rats, ovulation is provoked by mating.

In male humans and rats, the major organs that make up their reproductive system include the testes, scrotum, epididymis, prostate glands, seminiferous tubules, vas deferens, seminal vesicles, urethra, and the penis. In both humans and rats, the testes located in the scrotum, are the reproductive organs that produce sperm and male hormones (testosterone). The seminiferous tubules which are tightly packed coils located in the testes are the place in which sperm develop. In rats and humans, sperm are stored in the epididymis which is adjacent to the testes. Also, rats and humans both produce seminal fluid inside the prostate gland and seminal vesicles. A difference between rats and humans is that rats have a urogenital aperture and humans do not. Another major difference between rat and human male reproductive systems is that, during the non-breeding periods, rats possess the ability to retract the testes into the abdominal cavity. Humans cannot do this.

BSCS Biology: A Molecular Approach. Columbus, OH: Glencoe/McGraw-Hill Publishing Company, 2006. Print.

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Kimball, John. Kimball’s Biology Pages. 2010. Web. 2 June 2010.

National Kidney and Urological Diseases Information Clearinghouse. n.d. Web. 2 June 2010.

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Damon, Alan. Biology: Higher Level (plus Standard Level Options) : Developed Specifically for the Ib Diploma . Harlow: Heinemann, 2008. Print.

Neural Control of the Anterior Lobe of the Pituitary Gland (Pars Distalis)

The Hypophysial Portal Vessels

The hypophysial portal vessels ( Fig. 5.9 ) are so called because they transport chemical messengers from one capillary bed (primary capillaries) to a second capillary bed before entering the general circulation. In principle this is identical to the hepatic portal system , which transports substances from the primary bed of capillaries in the intestine and its appendages (e.g., pancreas) to a second bed of capillaries or sinusoids in the liver. Both the primary and the secondary (sinusoids) plexus of capillaries are fenestrated ( Fig. 5.7 ), which facilitates the transport of substances across the capillary wall. Hormones released from anterior pituitary cells are transported by pituitary veins into the systemic circulation, by which they are transported to their major target organs, the gonads and the adrenal and thyroid glands.

FIGURE 5.9 . High-power view through a dissecting microscope of the hypophysial portal vessels on the anterior surface of the pituitary stalk (left) of an anesthetized rat. Note how the portal vessels arise from the primary capillary bed on the median eminence (pink area to the left) and fan out over the anterior pituitary gland at the pituitary stalk junction to the right. The tubero-infundibular artery, a branch of the superior hypophysial artery, can be seen arching across the top of the stalk–pituitary junction where it enters the anterior pituitary gland. This artery passes through the anterior pituitary gland to supply arterial blood to the neurohypophysis.

Dissection to teach human body systems

Few experiences in the life sciences compare to dissection. Students thoroughly enjoy the opportunity to suit up and participate in this memorable, engaging, and interactive experience. Dissection supplies such as dissecting trays, dissecting scissors, and scalpels give learners the chance to feel they’re in an authentic laboratory or medical setting while enhancing their understanding of body systems.

Based on the body system being studied, students can dissect a preserved mammalian organ, such as a brain, kidney, heart, or eye. During thorough examinations of individual organs, students can easily relate structure to function.

Carolina offers a wide array of whole specimens for dissection, from simple invertebrates to complex mammals. If you’re teaching a class that emphasizes comparative anatomy, start with dissections of invertebrates, such as earthworms or grasshoppers, to get students interested and to introduce dissection techniques. Follow with dissections of higher vertebrates like frogs to give students the opportunity to compare body systems and structure and function between different classes of organisms. Preserved pigs offer a fantastic glimpse into the mammalian body and can give your class a first-hand look at body systems that are much like their own.

Choose Carolina’s Perfect Solution® specimens, our formaldehyde-alternative, for your dissection experience. This tissue fixative produces safe, non-toxic specimens that have lifelike tissue texture and color.

For new teachers or for teachers who are new to dissection, we offer inexpensive and reusable dissection mats and flip charts that walk students through a complete dissection—with concise, step-by-step directions and full color graphics. Do you need to refresh your skills? Carolina provides complete teacher’s manuals with all dissection kits. Plus, you can access free content concerning dissection safety and other relevant information about preserved specimens (such as storage and disposal).

15.10 Large Intestine

(named because its diameter is greater than the small intestine)

1. Cecum – beginning of the large intestine, pouchlike, closed end called the appendix (ileocecal valve)
2. Colon – ascending / transverse / descending / sigmoid
3. Rectum – stores waste before it is expelled from the body
4. Anus -muscular sphincter which controls the exit of waste

Functions –re-absorbs water and passes along material that was not digested contains intestinal flora (bacteria to break down cellulose, also produce intestinal gas)

Mass movements – large portions of the colon contract to move material through it, usually after eating (defecation)

Circulatory System Video Introduction

For our middle grades series with Pearson publishing we created a video for every topic in human biology. Pearson was kind enough to let us release a few, just so that you can get a taste for what we’ve been up to. In this video, we start off by using the road analogy to talk about the circulatory system. Jonas and Haley then take us all on an amazing journey through some of the most interesting facts about this human biology topic. We hope you enjoy it, we had fun making it!

Watch the video: Σημάδια Του Οργανισμού Ότι Καταναλώνετε Πολλή Ζάχαρη! (January 2022).