Exporting Function

The Common Vein copyright 2007


The exporting function of a biological unit is the function that enables the unit to bring to bear the fruits of its labor to the larger biological unit.  A farmer who has a large fruit and vegetable farm is not valuable to the society if he has no mechanism of delivering his product to the market.  He does not serve himself, his family nor community if the product is not deliverable.  Such is the case with each biological unit – thay each have to have a mechanism to deliver their products.   We will briefly introduce the exporting function of the systems in the body.

Nervous System

Among the many afferent functions of the brain and spinal cord we have chosen an image to represent the nerve supply of the heart.  The efferent system delivers a stimulus from the sympathetic and parasympathetic systems to the sinoatrial node which subsequently progressively exports the afferent signals to the atrioventricular node and then to each of the ventricles.

Efferent Nerves in Yellow for Cardiac Muscle Contraction –

This post mortem angiogram in the LAO projection shows normal right (RCA) and left (LCA) coronary arteries. The LCA is overlaid in bright red, and the RCA in maroon. The S-A node (yellow) is seen in the superior aspect of the RA. The bundle of His extends along the right A-V groove toward the crux of the heart. Tyhe right bundle branch courses along the right side of the septum and then courses along the free wall and turns up to the RVOT. The left bundle courses along the left side of the septum and divides into an anterior and posterior branch.33805SAAV04 Courtesy Ashley Davidoff MD. CVS heart artery coronary LCA RCA normal anatomy LAD circumflex PDA posterior LV SA node A-V node bundle of His right bundle branch left anterior branch posterior nerve supply cardiac coronary artery imaging postmortem angiography

Sodium Potassium Pump Mechanism in the Transmission of a Nerve Impulse 

Simeltaneous Importing and Exporting of Sodium and Potassium via an Active Pump and Passive Diffusion

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Synaptic Cleft Requiring Chemical Transmitters eg Acetylcholine to Transmit Impulse Across Nerve Junctions

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 Cardiovascular System

The cardiovascular system is a both receiver and exporter in its role as a major transport system in the body.  Among the multitude of transport functions, it can be simply viewed as having an arterial system that takes blood away from the heart and toward the organs and a venous system that takes blood away from the organs ands tissues and toward the heart.  It took our civilization many years to understand that the cardiovascular system was a circulation, reportedly discovered by William Harvey in the first half of the 17th century who noted that the exporting function and importing function were within and part of the same system.


Cardiac Ejection Arterial Blood Exported via the Aorta to All the Organs

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Cardiac Syncitium – Facilitating Efficient Receiving and Transmitting of Impulses
A drawing of the histology of the myofibrils of the heart showing how they ae connected and related as a continuum enabling a coordinated contraction pattern. Courtesy Ashley Davidoff MD. 32907 code cardiac heart muscle syncitium histology Davidoff art

Respiratory System

The respiratory system is a both receiver and exporter in its role as a major transport system in the body.  Among the multitude of transport functions it removes carbon dioxide from the lungs and transports it to the outside environment.  It thus also has a dual role as an exporter and importer. 


This diagram outlines the residual volume between the red lines, representing the air that is left in the airways and the alveoli after a full expiration. The air you may see on expiration CXR is the residual volume and as you can see it is about 1.8 liters in this patient. Courtesy Ashley Davidoff MD. 42529b06aa03

Gastrointestinal System

The gastrointestinal system is also a major transport system and each structure along its tract both receives and exports nutritional products and waste products.  The glands of digestion including the salivary glands, liver, via the biliary system, and the pancreas, all have ductal systems that enable their products to be exported to the sites of action. 

Exporting Products of the Liver and Pancreas via the Ampulla to the Duodenum

39962b03 Courtesy Ashley Davidoff MD code pancreas 39k pancreatic duct normal ampulla imaging radiology ERCP distal CBD

Intestinal Epithelial Cell – Import Export Function

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The urinary system is a both receiver and exporter in its role as a major transport system of water and electrolytes as well as nitrogenous waste in the body.  Among the multitude of transport functions it removes urea from the body and transports it to the outside environment.  It also has role of importing recycling and excreting water and electrolytes from the body.

Receiving and Exporting at Multiple Levels

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Urinal in Bruges, Belgium

82001p.800 interesting accessory urine urinary system genitourinary tract urine out put Courtesy of Ashley Davidoff MD Davidoff photo Bruges Belgium

The genital system transports its products via tubes as well.  The spermatazoa are exported from the testes via the vas deferens and are delivered via the urethra into the receiving vagina and cervix, while the ovum from the ovary is launched by the rupture of the follicle, and is exported to the endometrial cavity via the fallopian tubes.

Reticuloendothelial System

The reticuloendothelial system as a part of the defense system.  The lymphatics for example transport foreign material from the sites of origin to the lymph nodes where foreign sunstance is impounded.  A prime example is shown n the lymphatics of the lung below where inhaled anthracotic material is shown in the lymphatics of the lung on its way to the lymph nodes.  In the second image foreign material in the form of inhaled carbon and metastattic cancer have both been impounded by lymph nodes in the lung, having got there either via the lymphatics or via circulating macrophages which dumped the intruders in the lymph nodes.

Extraction of Inhaled Anthracite – Exporting to the Lymph Nodes

Anthracosis – Note the accumulation of carbon particles within the lymphatics along the interlobular septa, outlining the secondary lobules. The carbon particles are inhaled from an anthracotic urban environment. Courtesy Ashley Davidoff MD. 32291 code lung interlobular septum septa secondary lobule pulmonary lobule intertstitium interstitial grosspathology carbon

Carbon and Metastatic Disease in Regional Lymph Nodes

This is a post mortem specimen of a lung in a patient who had primary lung carcinoma with metastatic liver disease, portal vein thrombosis, and a pulmonary infarct in the LUL. Note the white metastatic nodules in the hilar lymph nodes, which are carbon filled. Courtesy Ashley Davidoff MD. a87-462 32192 code lungs pulmonary hilum lymph nodes nodule metastasis metastases primary lung grosspathology

Musculoskeletal System

The musculoskeletal system is mostly part of the transport system. It is hard to conceive the export function of the muscles for example until one thinks of muscle as an organ that contracts and relaxes.  The delivery of its action is caused by the contraction since without this part of the motion the function cannot be delivered.  The muscle is part of a mechanism that converts chemical energy to mechanical energy and it is the processing of the chemical energy and its setting up of the contractile elements that are part of its processing action while the contraction and subsequent relaxation is part of its delivery of services.  

The following tragic case of a bullet wound to the spinal cord resulting in quadraplegia.  The consedemonstrates the effect on the body including the muscular and skeletal system when they cannot function because of a control system that is non functioning.  The inabilty of the muscles to be able to relax, results in flexion contractues, and total inability to use the hands arms and legs.  This injury therefore results in the inability of the patient to stand, move or support the body, and the patient is ommitted to bed or wheel chair resulting in bed sores and consequently bone infection if obssessive skin care is not administered. The  inability to evacuate or void result in constant constipation and the need for a suprapubic catheter to empty the bladder.

A Single Disastrous Event – The Bullet can be Seen in the Spine next to the Last Rib
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