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Hepatic portal system

The liver is a complex biochemical processing plant. It packages nutrients absorbed by the digestive system; produces plasma proteins, clotting factors, and bile; and disposes of worn-out cell components and waste products. Instead of entering the circulation directly, absorbed nutrients and certain wastes (for example, materials produced by the spleen) travel to the liver for processing. They do so via the hepatic portal system    ( [link] ). Portal systems begin and end in capillaries. In this case, the initial capillaries from the stomach, small intestine, large intestine, and spleen lead to the hepatic portal vein and end in specialized capillaries within the liver, the hepatic sinusoids. You saw the only other portal system with the hypothalamic-hypophyseal portal vessel in the endocrine chapter.

The hepatic portal system consists of the hepatic portal vein and the veins that drain into it. The hepatic portal vein itself is relatively short, beginning at the level of L2 with the confluence of the superior mesenteric and splenic veins. It also receives branches from the inferior mesenteric vein, plus the splenic veins and all their tributaries. The superior mesenteric vein receives blood from the small intestine, two-thirds of the large intestine, and the stomach. The inferior mesenteric vein drains the distal third of the large intestine, including the descending colon, the sigmoid colon, and the rectum. The splenic vein is formed from branches from the spleen, pancreas, and portions of the stomach, and the inferior mesenteric vein. After its formation, the hepatic portal vein also receives branches from the gastric veins of the stomach and cystic veins from the gall bladder. The hepatic portal vein delivers materials from these digestive and circulatory organs directly to the liver for processing.

Because of the hepatic portal system, the liver receives its blood supply from two different sources: from normal systemic circulation via the hepatic artery and from the hepatic portal vein. The liver processes the blood from the portal system to remove certain wastes and excess nutrients, which are stored for later use. This processed blood, as well as the systemic blood that came from the hepatic artery, exits the liver via the right, left, and middle hepatic veins, and flows into the inferior vena cava. Overall systemic blood composition remains relatively stable, since the liver is able to metabolize the absorbed digestive components.

Hepatic portal system

This diagram shows the veins in the digestive system.
The liver receives blood from the normal systemic circulation via the hepatic artery. It also receives and processes blood from other organs, delivered via the veins of the hepatic portal system. All blood exits the liver via the hepatic vein, which delivers the blood to the inferior vena cava. (Different colors are used to help distinguish among the different vessels in the system.)

Chapter review

The right ventricle pumps oxygen-depleted blood into the pulmonary trunk and right and left pulmonary arteries, which carry it to the right and left lungs for gas exchange. Oxygen-rich blood is transported by pulmonary veins to the left atrium. The left ventricle pumps this blood into the aorta. The main regions of the aorta are the ascending aorta, aortic arch, and descending aorta, which is further divided into the thoracic and abdominal aorta. The coronary arteries branch from the ascending aorta. After oxygenating tissues in the capillaries, systemic blood is returned to the right atrium from the venous system via the superior vena cava, which drains most of the veins superior to the diaphragm, the inferior vena cava, which drains most of the veins inferior to the diaphragm, and the coronary veins via the coronary sinus. The hepatic portal system carries blood to the liver for processing before it enters circulation. Review the figures provided in this section for circulation of blood through the blood vessels.

Questions & Answers

what are silhouettes
Magret Reply
is dis Medical term?
Preity
yes
Magret
but I don't know what it means
Magret
silhouette outline of a figure. The sharpness of the silhouette is a function of the shape, size and density of the object. This is most marked in radiography. basketball-shaped silhouette the enlarged cardiac outline seen in the dorsal-ventral view of the thorax in a dog with chronic pericardial
Callisto
why are postsynaptic ganglionic neurons unmyelinated
Callie Reply
Postganglionic motor neurons are unmyelinated because the lack myelin sheath. The myelin sheath on the peripheral nervous system is composed of Schwann cells wrapped around the axon inside the endoneurium.
Carmelo
they lack*
Carmelo
Postganglionic (and preganglionic) motor neurons belong to the division of the autonomic nervous system. In contrast, the somatic nervous system contains only one long thick myelinated somatic presynaptic motor neuron.
Carmelo
anatomy defination in urdu
Atif Reply
human body largest organ.....
jasveer Reply
liver
JOY
liver
Lem
Skin
amen
lungs
Zamiir
liver and skin
Marina
skin
brian
by mass is liver but externally is de skin
Kumsah
all answers Are correct
brian
no
Rehman
liver is the largest gland of the body but skin is the largest organ of the body
Rehman
so please what is the answer now
Marina
afcous skin.because difference between Gland and organ
Safiya
Only the skin
Williams
The largest organ is the skin and the liver is a gland
Williams
skin is the largest organ of the body
Denis
liver
julie
it's the skin
trinna
skin 100%
Mallikharjun
largest organ- liver largest system- Skin
Shahriar
largest organ is skin because it covers the rest of the organs
Syed
liver right answers
nisha
liver
Justine
skin
Areej
liver is largest gland
Areej
skin is largest organ liver is largest gland femur is largest bone thyroid gland is largest endocrine gland seratus muscle is largest muscle
Tanveer
sciatic nerve is largest nerve
Tanveer
portal vein is largest vein
Tanveer
GIT is largest tube in body
Tanveer
explain about cerebrum cereblum and pons medulla
Tanveer
Nervous system anotomy and physiology
Tanveer
skin is the human body's largest organ
Kimbley
@Tanveer, the cerebrum consists of the cerebral cortex, corpus callosum, hippocampus, and basal ganglia. The cerebellum is located inferior to the occipital lobe. The pons and medulla are part of the lower brainstem.
Carmelo
The cerebral cortex are divided into 4 lobes and control functions such as: thinking, learning, speech, sensory perception, motor functions, hearing and vision, etc. The cerebral cortex is mainly present only in mammals due to evolution. The hippocampus plays a main role in memory formation.
Carmelo
The cerebellum works together with the motor cortex and other parts of the brain to coordinate and fine tune muscular activity. The pons and medulla control autonomic functions such as: sleep, respiration, swallowing, vomiting, heart rate, vasomotor control and more other things.
Carmelo
skin hai friend
Tilak
what is the biliary tract
famuyiwa
The biliary tract involves the liver, gallbladder, and bile duct. Certain liver cells (hepatocytes) synthesize bile salts derived from cholesterol in response to Secretin hormone. The gallbladder stores the bile. Gallbladder releases bile to the bile duct in response to Cholecystokinin hormone.
Carmelo
The role of bile is to emulsify fats so that they can be easily broken down and absorbed by the enterocytes into the lacteal vessels.
Carmelo
what is the difference between negative feedback loop and positive feedback loop
famuyiwa
what is cholesterol
Kay
unsaturated fats
famuyiwa
so what is the main purpose of anomaly
Kay
Cholesterol is a waxy substance your body uses to protect nerves, make cell tissues, and produce certain hormones.
Favour
Cholesterol is a type of lipid and it is a nonpolar molecule. The molecule is mainly composed of hydrocarbon chains. Cholesterol is synthesized in the smooth endoplasmic reticulum in eukaryotic cells, and is the main building block material for steroids, Vit D, and bile salts.
Carmelo
Negative feedback loop reverses any change back to its set point. For ex, when your internal body temperature rises above 98.6 F, your hypothalamus triggers your dermal blood vessels to dilate and activate sweat glands through sympathetic motor nerves so you can sweat and cool off back to 98.6 F.
Carmelo
Positive feedback loop amplifies a change. For ex, during labor, oxytocin is released continuously in a positive feedback loop from the posterior pituitary gland to stimulate contraction of the myometrium so the baby can come out.
Carmelo
define homeostasis and explain it's importants
Adusei Reply
define the important life processes of humans
Adusei
how the bone marrow transplantation is done?
Tanveer
what is homeostasis
julie Reply
internal temperature of body
Sanket
Homeostasis is the internal constancy in which your body tries to maintain for optimal cellular functioning. For example, your body tries to maintain an internal body temperature of about 98.6F for optimal functioning of your body.
Carmelo
If a prolonged lost of homeostasis occurs, death of the organism will be the outcome.
Carmelo
Another example of homeostasis is that your body tries to maintain a specific blood sugar level, so that your cells can undergo constant cellular respiration and keep you alive.
Carmelo
homeostasis is the fairly constant internal changes of an environment (your internal environment).The temperature of a body must be kept between the range of 37.5°c
raphael
which tissue is more sensitive
Rit Reply
to what?
Lari
myasthenia gravis?
Selva
Myasthenia gravis is an autoimmune disease in which your own antibodies (produced by plasma cells) attack and inhibit nicotinic receptors at the neuromuscular junction.
Carmelo
As a result, acetylcholine will not bind to nicotinic receptors and now action potential is produced on the sarcolema. If no AP is produce, then there is no contraction of the muscle. For a long period of time, this will result in atrophy and muscle weakness.
Carmelo
and no action potential*
Carmelo
explain types of hypertension
Juli Reply
What is bulbar paralysis?
Roshni Reply
how can make penis larger
Marwat Reply
what is the stimuli initiates the control of erythropoiesis?
Ok Reply
oxygen
Liyungu
Erythropoietin, a hormone synthesized and released by the kidneys stimulate erythropoiesis in red bone marrow. When an Individual loses blood (hemorrhage) and the concentration of RBCs or oxygen decreases, erythropoitein will be released.
Carmelo
how lymph is from
Hafsa Reply
Lymph is essentially interstitial fluid that ends up in the lymphatic vessels that didn't go back into the venules. Lymph is composed of the same components as your blood plasma which contains water, solutes, oxygen, CO2, foreign particles such as toxins, bacteria and viruses.
Carmelo
what is the cause of twins
Clarus
The cause of identical twins is when a single fertilized egg undergo mitosis (splits in two) . As a result, both eggs now have the same genetic information, therefore producing two identical twins.
Carmelo
Different twins (fraternal) occurs when two different eggs are ovulated and two different sperm fertilize each egg. As a result, fraternal twins are not genetically identical and can even be opposite sex.
Carmelo
Fraternal twins occurs when two different eggs are ovulated and two different sperm fertilize each egg. As a result, fraternal twins are not genetically identical and can even be opposite sex.
Carmelo
If two eggs are ovulated during ovulation, and two different sperms fertilize each egg then fraternal twins will occur. Fraternal twins are not generically identical and can even be opposite sex.
Carmelo
Fraternal twins occurs when two different eggs are ovulated and two different sperm fertilize each egg. As a result, fraternal twins are not genetically identical and can even be opposite sex.
Carmelo
how structure and function relate to each other?
Garmai
This is a very important rule in Anatomy and Physiology. The structure of a cell, tissue, or organ will tell you a lot about it's function.
Carmelo
For example, simple columnar cells (enterocytes) in the villus present in the duodenum of the small intestine contain microvilli. Microvilli are finger like projections of the cell membrane (produce by the cytoskeleton)that increase the surface area for absorption of nutrients into the enterocytes.
Carmelo
The main role of these enterocytes is to absorb. Therefore, having Microvilli as a structure relates to its function.
Carmelo
@ Carmelo thanks for the answer.
Garmai
welcome
Carmelo
what is the difference between negative feedback loop and positive feedback loop
famuyiwa
what is anatomy
Kamran Reply
is simply defined as the stody of internal and external structure of human body and the relationships between the body part.
Surajo
Anatomy Is The Study Of The Structure Of The Human body
Dennis
anatomy is the science that deals with the study of the body structure
Vida
what is stress hyperglycaemia and Pathophysiology
amani
Hyperglycemia is the term used when somebody is in a state of high blood sugar levels. For example, after you eat a meal with carbohydrates in it, (post-absorbptive state) your blood is hyperglycemic.
Carmelo
Pathophysiology is the study of how diseases function and cause abnormal functioning in the body. Usually pathophysiology is studied at a molecular/cellular level.
Carmelo
I meant to say absorbptive* state on explanation of hyperglycemia. Usually during post-absorbptive state your blood has low blood sugar levels.
Carmelo
Explain two best methods of avoiding pregnancies as adolescents
Bright
what is sex?
Soumyakanta Reply
Your biological sex is determined by your sex chromosome which is pair number 23. if you have a XX pair then you are a female. if you have XY pair then you are a male.
Carmelo
the sex chromosomes are called as allosome
Tanveer
True, the other 22 pairs are called autosomes :)
Carmelo
why the left hemisphere controls the right side body parts and right hemisphere controls the left side body parts?
Tanveer
because it is like that
Sherin
It has to do with how the neuronal pathway are intertwined to opposites sides of the body I think. A motor output from the left cerebral hemisphere (motor cortex) will end up stimulating your right side of the body.
Carmelo
brother Carmelo don't miander, sex ,it just the state of being a male or female
Liyungu
Your biological sex is tied to your DNA (genetic information). A male have testes and female have ovaries which are reproductive organs is tied to your genetic information (sex chromosome). If an individual feels like it is either a male or female is called gender identity.
Carmelo
thanks our beloved brother Carmelo
Liyungu
that's great learning something everyday
Tasheria
what is anatomy
Rohino
most blood enters the ventricle during what phase?
Tina Reply
rapid ejection
Tanveer
Most of the blood in the heart enters the ventricles during the diastolic phase.
Carmelo
ok
ren
which of the following is the types of personal protective equipment protects mucous membranes?
Garmai
Most (not all) mucous membranes secrete mucus because they contain goblet cells in between the epithelial tissue. Mucus coats the layers of epithelium and traps particles. The epithelial type is either stratified squamous, simple columnar, or pseudostratified columnar in mucous membranes.
Carmelo
Are you a professor Carmelo?
Sherin
No sir, I'm a nursing and biology student as well in university.
Carmelo
smart!
Sherin
thanks!
Carmelo
why the fever occurs if any injury or pain occurs
Tanveer
fever is de best indication to show there is an infection
Kumsah
what is the actual mechanism of fever
Tanveer
correct Tanveer, the normal internal body temperature is 98.6 Fareinheit. When the temperature rises above 100 fareinheit, it is usually an indication of infection.
Carmelo
White blood cells which protect you against foreign antigens become active and release cytokines (pyrogens) during infection which causes the hypothalamus to raise your internal body temperature.
Carmelo
thank you so much.really you are very intelligent.
Tanveer
thank you. you are very intelligent
Tanveer
the mechanism of fever appears to be a defensive reaction by the body against infectious disease. when bacteria or viruses invade the body and cause tissue injury one of de body immune system's responses is to produce pyrogen
Kumsah
Yes, the hypothalamus responds to pyrogens by raising your body temperature. The reason your hypothalamus does this is to stunt the growth and metabolism of whatever is causing the infection (bacteria, virus, fungi protozoa, etc.)
Carmelo
how the kidney transplantation is done
Tanveer
Which university are you studying?
Sherin
karnataka
Tanveer
and all of you ,university
Tanveer
Really so talented
Savita
I was asking Carmelo?
Sherin
Georgia State University.
Carmelo
oh nice! I'm in University of Texas
Sherin
nice!!!
Carmelo
vicious this is chaptare I reading 5day after
Taufik
pleas sir can u teach me
Taufik
not sure, can u help me?
Nichole
I'm in University of Technology, Jamaica
Nichole
why do you not helf me
Taufik

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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