Organ Systems

digestive system

The Gastrointestinal Tract

1 Comment / Anatomy, Digestive System, health, Organ Systems, Science

The gastrointestinal tract, or digestive system is the organ system responsible for consuming and digesting food while absorbing the nutrients, then expelling waste. This consists of all organs between the mouth and anus. It is also essential for immune functioning, and homeostasis in the body.

The organs that comprise the tract are the following organs following the oral cavity, which secretes saliva from 3 distinct glands in the mouth, which consist of large amounts of smaller glands, leading down:

  • the esophogus – the foodpipe leading to the stomach, consisting of a fibromuscular tube aided by peristaltic contractions
  • stomach – a muscular and hollow dilated organ that secretes protein digesting enzymes and strong acids to breakdown food in digestion by contorting smoothly to send the partially digested chyme to the small intestine.
  • duodenum – the first section of the small intestine, where the majority of chemical digestion takes place. Specific glands called intestinesBrunner’s glands secrete a mucus rich alkaline containing bicarbonate to neutralize stomach acid, lubricate intestinal walls, and give the alkaline enzymes ability to absorb the acidic chyme. It breaks down food with leafy shaped villi and the malaria mucosae loaded with enzymes lining the intestinal walls. The duodenum regulates the stomach via hormonal pathways, when the stomach releases chyme (partially digested ball of food) through the pylorus (stomach opening) which is when Secretin and Cholecystokinin release causing the liver and gall bladder to release bile, and the pancreas to produce bicarbonate and other digestive enzymes: tripsin, amalase, and lipase, sucrase, maltase, and secretin
  • the jejunum – the second part of the small intestine that is exposed to food, and lined with nutrient absorbing mucosa called villi. The villi in the Jejunum are much longer than those in the Ileum and Duodenum. It is a site of active transport of amino acids, small peptides, vitamins and glucose and passive transport of the sugar fructose. The Jejenum is about 2/5th of the entire small intestine length (~7m in an adult male, highly variant).
  • the Ileum – the final section of the small intestine that is indistinguishable from the Jejenum in humans that is abousmall_intestinet 2-4 meters long and connects with the cecum, the first portion of the large intestine.  It absorbs mostly vitamin B12, bile salts, and other digestive products left by the jejunum. This tract has folds of villi and microvilli to allow for maximum surface area for absorption of enzymes and digestive products. The diffuse neuroendocrine cells secrete their various hormones and the final digestion of proteins and carbohydrates takes place before passing the remaining chyme to the colon(large intestine).
  • the cecum – a pouch at the beginning of the large intestine, that contain the appendix (a proposed vestigial structure remaining from herbivore ancestors by Darwin), which is mostly vestigial and a dead pouch at the beginning of the large intestine
  • the colon – categorized into ascending, transverse, descending, andcolon sigmoid the large intestine is responsible for water absorption and the last remains of food before it is emptied into the rectum. The ascending and transverse are responsible for water absorption and the descending parts of the colon prepare waste for removal, storing it until it is removed for a bowel movement. The sigmoid portion of the colon allows for storage and release of gas, without (hopefully!) releasing fecal matter.rectum
  • the rectum – The rectum is the final part of the small intestine, it acts as a temporary storage point for fecal matter and then releases through the anal canal, but acts as a flexible point of temporary storage.
  • the anal canal – the final passing point between the rectum and the environment, it is about 3-4 centimeters long and is classified into 3 parts. The lining becomes more skin like as it descends and it gets a significant amount of blood flow.

This system allows for the absorption of nutrients for the body to use in all of its processes, but breaking down the food requires energy and vigilance for dangerous bacteria and viruses that could be contained in the nutrients as they are assimilated into the body. The entire tract is about 30 feet long and has specialized sections devoted to various tasks and release of hormones and enzymes into the chyme as it moves down the tract and is finally expelled.

Food moves through the body after chewing and swallowing via peristalsis in the esophagus, which moves food into the stomach after about 8 or 9 seconds. Secondary waves can occur to move larger chunks of food down the throat in addition to the primary wave, and stretch and reflexes activate until it is moved into the stomach. Once processed by the stomach, chunky chyme is moved through the pyloric sphincter into the duodenum. Then slower waves occur that mix, rather than move, the chyme with the intestinal enzymes, hormones, and fluids for absorption. Once the chyme reaches the large intestine, it moves with periodic movements of mass which occur a few times per day to expel waste towards the rectum.

The gastrointestinal tract is largely responsible for homeostasis in the body; there are massive amounts of hormones secreted by the organs to break down and assimilate nutrients alongside enzymes. The gut is largely responsible for endocrine and lymphatic efficiencies because the gastrointestinal tract is a source for the nutrients of both systems. These two factors work together with bile from the liver and gallbladder to break down and assimilate the desired nutrient bodies. In the intestines, all forces of the body work together to move food through the system and assimilate it without contracting pathogens.

The gastrointestinal system has enormous effect on the rest of the body, because it is where nutrients are restored to all systems for continued growth, including the nervous system, muscular-skeletal systems, endocrine system, lymph system, and circulatory system. Diet is one of the most important contributors to the body’s overall homeostasis, which can include mental health. Studies are finding more links and correlations between diet and mental health. Many studies have found links between depression and nutrition, including mood correlations. There is more and more research linking happiness to diet; seratonin, the supposed happiness neurohormone is 90% in the gut. Whole, unprocessed foods with dense nutrients and variety coinciding with seasonal availability tends to be optimal for the system.

  1. What diets have you found to be useful?
  2. What foods have and haven’t worked?
  3. What types of organic processes are you interested in learning more about?

 

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Endocrine System – The Body’s Way of Talking

1 Comment / Anatomy, endocrine system, health, Neuroscience, Organ Systems, Science, yoga, yoga benefits

Endocrine System: Chemical Communication

The endocrine system refers to a collection of glands that secrete hormones into the circulatory system to target a distant organ with chemical messages. These tend to be slower processes, such as growth, menstrual cycles, or circadian rhythms, but also refer to procedures for dealing with stress and the environment. The notable endocrine glands are:

  • the pituitary gland – about the size of a pea, this gland protrudes atpituitary gland - the Endocrine System the base of the hypothalamus, there are two lobes in humans that regulate growth, blood pressure, pregnancy and childbirth, breast milk production, sex organ functioning, thyroid gland function, metabolism, osmolarity and water balance, temperature regulation, pain relief and sleeping patterns (but this is mostly the responsibility of the pineal gland. This is the seat of control of the mind over the entire body, hormonally speaking.
  • the pineal gland – The gland produces melatonin to regulate sleep cycles and circadian rhythm and the hormone is very sensitive to light. Descartes viewed the gland as the gateway between the body, mind, and soul and considered it to be the third eye. When children become teenagers, production becomes delayed leading to later sleeping and waking times.
  • the pancreas – largely regulates the digestive and lymphatic pancreas - the Endocrine Systemsystems, secreting insulin, glucagon, somatostatin, pancreatic peptide, and assists in digestion by secreting pancreatic which is a blend of digestive enzymes
  • ovaries, testes – ovaries release: estrogen, testosterone, progesterone, and unfertilized eggs; testicles release sperm and androgen (steroid hormones, primarily testosterone)
  • thyroid gland – one of the largest endocrine glands with two lobes around the trachea, below the thyroid cartilage also known as the Adam’s apple. It controls how quickly the body uses energy, makes proteins, and uses other hormones. It does this by producing hormones that regulate growth and rate of function of othethyroid gland - the Endocrine Systemr systems. Hormonal output of the thyroid gland is controlled by thyroid stimulating hormone produced by the anterior pituitary lobe, which itself is regulated by thyrotropin-releasing hormone produced by the hypothalamus
  • parathyroid gland – Humans usually have four, located on the back of the thyroid gland that produce parathyroid hormone and calcitonin. Together, these hormones regulate bone physiology including calcium levels and phosphate levels and reabsorption levels via the kidneys, so that the levels of these chemicals are optimal for the nervous and muscular systems to function
  • hypothalamus – a small portion of the brain located just above the brain stem with specialized cells to link the nervous system to the endocrine system via the pituitary gland. All vertebrate brains have a hypothalamus, which produce neurohormones that stimulate the secretion of pituitary hormones, controlling body temperature, hunger, thirst, and fatigue, different processes of the autonomic nervous system.
  • gastrointestinal tract – releases hormones to help regulate the digestive process, including gastrin, secretin, cholecystokinin, and ghrelin
  • adrenal glands – endocrine glands that sit atop the kidneys, responsible for stress hormones cortisol and corticosteroids, and also catacholamines, like adrenaline and noradrenaline. These cells also produce androgens to assist the body in dealing with stress, and the glands activate both the nervous and endocrine systems to work react to stress.

These glandular organs together make up the endocrine system, which sends chemical messages throughout the body, similar to the nervous system, however, the effects and mechanisms of the system are very different in their processes.

Glands? What are those?

The word gland is used for any organ that is used to excrete hormones for release into the bloodstream or into cavities inside of the body or to its outer surface. There are also two types of glands to be aware of: endocrine and exocrine; the latter uses ducts and bodily cavities for transport while the former uses the circulatory system for transport.

The exocrine system is a collection of glands that operates differently than the endocrine system, but is extremely useful to the body. The exocrine system uses three different methods of excretion:

  1. Merocrine glands – cells excrete their substances by exocytosis (cellular waste removal by containing the waste,then releasing it
a mammary gland
a mammary gland – the Endocrine System

outside of the cell): i.e. pancreatic acinar cells

  • Apocrine glands – cells that excrete by concentrating their waste, then cutting of a bud of the cell with the waste
  • Holocrine glands – The entire cell disintegrates to release its substance

    • It is easiest to understand the exocrine system by how it functions: it comprises sweat glands, salivary glands, mammary glands, and the liver. Together, the exocrine and endocrine systems work all of the glands of the body to remove waste.

    Endocrine System Bodily Operations

    The endocrine system operates differently from the exocrine system, in that it works via the circulatory system. Many organs have secondary endocrine functions in addition to their primary roles in the body. Endocrine organs usually signal themselves in groups and in certain orders, referred to as an axis. The Greek words ἐνδο- endo-, inside or interior and κρίνειν krinein, to separate or distinguish are  useful for understanding what the endocrine system does. It is essentially specializing specific organs to work in unison for specific bodily functions, including growing, sleeping, and the most basic of physiological needs, such as hunger and urination. In unison with the nervous system, this is how the body communicates internally.

    I will go into more detail in later articles about the particular neuroreceptors and hormones that the body uses for specific functions. Keep in mind that many are still unclassified and have properties that have not yet been observed and measured. The science of endocrinology and neurology have vast horizons to cover before we truly understand how these systems interrelate and function to produce conscious thought. But here are some great graphics of the known hormones and their organs of origin, thanks wikipedia!

    Endocrine_central_nervous


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    The Lymphatic System

    1 Comment / Anatomy, health, Lymph system, Organ Systems, Science

    The Lymphatic system works in conjunction with the circulatory system to reroute 3 liters of the ~20 processed each day by the body to replace plasma in the blood. Lympha is the Latin word for ‘water’ and refers to the clear liquid that provides autoimmune defense and assists with digestion. The Lymphatic system works alongside the circulatory system to remove waste, toxin, and provide defense for the body from pathogens, infection, and disease.

    In order to continue, we have to examine a few of the different fluids in the body:

    • Blood Plasma – the pale yellow liquid in blood, makes up 55% of the bodies total blood, is made up of 95% water, and contains Cellular_Fluid_Contentdissolved proteins, glucose, coagulation factors, electrolytes, hormones, and carbon dioxide
    • Intracellular Fluid –  Cytosol, or intracellular fluid, is the liquid found inside of cells separated into compartmental membranes
    • Extracellular Fluid – fluid outside of cells, mainly blood plasma and interstitial fluid that, in conjunction with intracellular fluid, helps to control movement of electrolytes and water in the body
    • Interstitial Fluid – surrounds the cells of multicellular animals, and is found between the tissue spaces, is very similar to plasma, and pushes water out of capillaries to dispose of waste and continuously reinvigorate the blood stream with water using osmosis and hydrostatic pressure.
    • Transcellular Fluid – the total body water contained within epithelial lined spaces (gastrointestinal, cerebrospinal, peritoneal, and ocular fluids)

    We also have to examine the two different parts of the immune system:

    1. the innate immune system – provides immediate defense against infection, found in all plant and animal life. Evolutionarily, this is a much older defense system and is dominant in plants, fungi, insects, and very primitive multicellular organisms. This system activates the adaptive immune system in multicellular organisms
    2. the adaptive immune system –  also known as acquired immunity, this is a subsystem composed of highly specialized, systemic cells and processes that eliminate and/or prevent pathogen growth. This creates immunological memory in response to specific pathogens leading to enhanced responses with subsequent encounters. This is the entire basis of vaccination. Pathogen specific receptors are acquired during the lifetime of the organism. This can be helpful in cases where the body adapts positively, or this can be harmful when autoimmune diseases are acquired. This system is highly adaptable because of somatic hypermutation and somatic recombination (V(D)J recovery) allows for agile re-creation of anti-body cells to fight new pathogens. The antigen receptors are then uniquely expresses on each lymphocyte. This brings us back to where we started….

    The Lymph system is therefore extremely involved in the body’s response to pathogens, viruses, and bacteria. Both the innate and adaptive immune systems have humoral and cell mediated immunities (humoral refers to lymph fluid). Remember the two systems, and how blood is contained in a closed system, and lymph is more open. This is a major part of what takes waste out of the bloodstream, and more specifically, how the body fights off infection and eliminates harmful micro-organisms.

    So all together, your body is consistently reproducing certain cells to fight off bad guys. and it uses this liquid transport system, which is open around the blood vessels, to do it. This is the final piece of the puzzle, the different types of adaptive immune cells called lymphocytes:

    • Killer T cells – a subgroup of T cells that kills cells infected with a virus or that are damaged or dysfunctional
    • Helper T cells – regulate both innate and adaptive immune responses to help determine the body’s response
    • Gamma Delta T cells – these cells are hard to classify and skirt the border between innate and adaptive cells.
    • B lymphocytes and antibodies – identifies pathogens then (this is where the magic happens, this is from Wikipedia) this antigen/antibody complex is taken up by the B cell and processed by proteolysis into peptides. The B cell then displays these antigenic peptides on its surface MHC class II molecules. This combination of MHC and antigen attracts a matching helper T cell, which releases lymphokines and activates the B cell.[61] As the activated B cell then begins to divide, its offspring (plasma cells) secrete millions of copies of the antibody that recognizes this antigen. These antibodies circulate in blood plasma and lymph, bind to pathogens expressing the antigen and mark them for destruction by complement activation or for uptake and destruction by phagocytes. Antibodies can also neutralize challenges directly, by binding to bacterial toxins or by interfering with the receptors that viruses and bacteria use to infect cells.[62]

    So essentially, these specialized cells identity, swarm, and kill pathogens, using the lymph system for circulation and of powerful anti-pathogen cells. This is why the body’s fluid content is so important; it allows the body to regulate and defend itself.

    Now let’s talk a bit about the specific organs of the lymphatic system:

    • Lymph vessels – these conduct lymph between the different parts of the body. The lymph vessels transport lymph back to the blood stream replacing the volume lost from the blood during the formation of the interstitial fluid
    • Thymus – The Thymus is extremely important for the immune system, it is where T cells mature, in front of the heart and behind the sternum. It has two lobes that surround the trachea
    • Spleen – an organ found in all vertebrates, this is similar to a very large lymph node to act primarily as a blood filter. It is possible to remove the spleen and maintain life. It recycles iron and stores blood; it also synthesizes antibodies. Its absence will cause predisposition to certain infections. lymph_node_structure
    • lymph nodes – an organized collection of lymph tissue that lymph fluid passes through on its way back to the blood stream.
    • lymph follicle – A lymph follicle is a dense collection of lymphocytes, the number, size and configuration of which change in accordance with the functional state of the lymph node

    So you can see that the system works very much in unison with the other bodily systems, mainly the circulatory and gastrointestinal systems to remove wasteful byproducts and toxins involved in consuming food orally. You can feel the concentrations of lymph nodes on the sides of your neck, at the top of the rib cage, and on the soft portion of the elbows and knees.

    I think I will post another article on the adaptive immune system, there is just so much here. This should be pretty comprehensive on the lymph system as a whole, but ask any questions and I’ll try to figure it out!

     

     

     

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    organ systems

    Organs Systems of the Human Body

    1 Comment / Anatomy, health, Organ Systems, Science

    An organ is a collection of tissues joined structurally that have a common function. Functionally related organs cooperate together to form organ systems. Essentially organs work together to serve functions for the overall well-being and recycling of the body’s energy.

    The functions of organs and organ systems tend to overlap; in these cases, it is particularly useful to discuss the connection and shared functionality between the organs that overlap. The human body has 11 distinct organ systems that work in unison to keep the body functioning optimally:

    1. Cardiovascular
    2. Digestive
    3. Respiratory
    4. Nervous
    5. Muscular
    6. Skeletal
    7. Urinary
    8. Reproductive
    9. Lymphatic
    10. Endocrine
    11. Integumentary

    The Cardiovascular System

    Major Organs: Heart, Blood vessels (arteries, veins, and capillaries)

    The cardiovascular system, combined with the respiratory system form the basis for the circulatory system in the human body, supplying tissues with nutrients and oxygen, while allowing waste and carbon dioxide to be excreted from the tissue. Capillaries are the single celled veins that form the wall between tissue and arteries and tissue and veins.

    Artery walls are thick and are pressured to pump blood from the heart to the organs. The aorta, pulmonary artery, femoral arteries, the carotid arteries, and the coronary arteries. Oxygen rich blood flows through the arteries from the heart to the various organic tissue within the body.

    Veins carry oxygen depleted and carbon dioxide back to the heart from the bodies various tissues. Veins are much thinner than arteries, but have valves to help keep the blood flowing in one direction. The superior vena cava, the inferior vena cava, the pulmonary vein, the jugular veins and the great saphenous veins are all major veins in the body that can be considered the most prominent.

    The Digestive System

    Major Organs: Mouth, Teeth, Salivary Glands, Tongue, Pharynx, Esophagus, Liver, Gallbladder, Stomach, Small Intestine, Large Intestine, Pancreas, Appendix, Colon, Rectum, Anal Canal

    The digestive system is a group of organs working together to convert food sources into energy for the body to assimilate, then use. This is the primary mover of the bodies energy; it allows for processing and absorption of the environment. From the time food enters through the mouth, it is being digested by enzymes in mucus. Remember to chew your food well, the more broken down the food is, the easier it is to digest.

    The Respiratory System

    Major Organs: trachea, bronchi, bronchioles, lungs, and diaphragm

    The respiratory system is a series of organs responsible for intaking oxygen from the atmosphere and expelling carbon dioxide back into the air. This basic gas exchange between the body and the atmosphere is completely dependent upon the respiratory system. This exchange affects every other system, as they oxygenation of blood is necessary in every organ. The nervous system also seems to draw energy from the respiratory system, and the cardiovascular system takes cues to determine how much blood it should be pumping based on breath rate.

    Yoga focuses primarily on the respiratory system’s functioning to move the muscular-skeletal system. The respiratory system is vital to the functioning of every mammal on the planet.

    The Nervous System

    Major Organs: Brain, Spinal Cord

    The nervous system is the body’s communication network. It begins in the brain and runs through the brainstem down the spinal cord and into the extremities. Sensations are felt at the fingers via pressure receptors, then are sent through the body’s nerves to the spinal cord, then up into the brain. The nervous system consists of nerves, which are specialized cells used to transmit and receive information.

    Nervous tissue first arose with worms over 500 million years ago. The simplest worms have a few hundred nerve cells, while humans have over 100 billion nerve cells. Neuroscience is the field that studies the nervous system in detail.

    The brain is the control center of the body. It is where all information stems and must eventually return to be processed.

    The Muscular and Skeletal Systems

    The muscular and skeletal systems, though distinctly different, belong together. Muscles move bones through space and bones support organs as they move through space. Together, muscles and bones create the support structure that is your body. Bones are organs, they grow as you do and fuse together as you mature. This system is intricately related to the nervous system, as the three work together to provide a functional feedback loop within the body so that as it moves, it can adjust to the environment.

    The muscular-skeletal system requires constant maintenance, as it would have been the primary means of survival in humanities beginnings. Many of the problems in the modern world result from not using this system properly, or often to ensure that it maintains itself in a healthy and optimal way.

    The Urinary System

    Major Organs: Kidneys, Ureter, Urinary Bladder, Urethra

    Humans produce on average 1-2 liters of urine per day, the urinary system is the removal of urea and uric acid. The kidney receives about 20% of the blood from the heart to break down into urine.

    The urinary system also assists in regulation of electrolytes, ph balance of the blood, and controlling blood volume and pressure. This is the bodies balancing system for the blood stream and is used in the wild extensively for communication between animals in similar areas. marking territory, or submissiveness uses the urinary system.

    The Reproductive System

    The reproductive system are sex organs. They allow for reproduction while insulating vital organs from infection and bacteria (ideally). This allows for the combination of genetic material of two individuals. Hormones affect the growth and maturation of sex organs and many other systems are involved in the creation of offspring, but the sex organs are the primary movers of the genetically encoded cells required for reproduction.

    The Lymphatic System

    The lymphatic system is a circulatory system that carries lymph, a clear liquid (from the word for “water” in Latin) towards the heart. This is an open system that allows for excess plasma in the blood stream to get re-introduced after storage. This is the primary function, along with functioning of the immune system.

    Lymph contains plasma, but also white blood cells, lymphocytes, waste, bacteria, and proteins. Lymphocytes, a type of white blood cell concentrated in the lymph nodes, is very present in the spleen, tonsils, thymus, bone marrow, and lymphatic digestive tissue.

    The lymph system does not have a primary mover, as the circulatory system has the heart, though some animals have lymph hearts. It is moved via the muscular-skeletal and digestive systems, but it remains an open system. Bone marrow is responsible for the creation of T cells, which then move to the thymus for maturation. Afterwards, they combine with B cells in search of pathogens, but 95% of the cells begin aptosis (preprogrammed cell death).

    The Endocrine System

    Major Organs: Pineal Gland, Pituitary Gland, pancreas, ovaries, testes, thyroid gland, parathyroid gland, hypothalamus, gastrointestinal tract, and adrenal glands

    The endocrine system is a collection of glands that secrete hormones into the circulatory system that are carried towards target organs. These are information signals similar to the nervous system, yet its effects and mechanisms are much different. These are slower, more gradual effects, take longer to process and effect the system and are slower to stop affecting the system as a whole. The hypothalamus is the seat of control of the endocrine system in all vertebrate mammals. Many other organs also have secondarily endocrine functions for the body.

    The endocrine system quickly becomes chemistry and cell biology, so we will revisit this in detail in a future article. But essentially, the endocrine system is responsible for changing the body slowly, such as in growth, maturation, disease, reproduction, puberty, menopause, and many other common events we see as humans age.

    The Integumentary System

    The integumentary system protects the body, including from loss of water or abrasion. It serves a variety of functions: waterproof, cushioning, and protecting deeper tissue, excreting wastes, regulating temperature, and is the attachment site for sensory receptors to detect pain, sensation, pressure, and temperature. The skin, nails, feathers, hair, scales, and hooves are all part of the integumentary system. It also allows for vitamin D synthesis in conjunction with the sun.

    The skin is the largest organ in the body and is integral to functioning, containing 12-15% of our body weight. There are three layers, the epidermis, the dermis, hypodermis. The epidermis is the outermost wall of skin. Keratin stiffens epidermal tissue to form fingernails. Keratin aids in protection. The system also protects against a variety of things: UV rays, body maintenance, protection from dehydration, excretion of waste through perspiration, protecting internal organs, and much more.

    The body is a complex playground of intermingling chemical and biological behaviors, many of which are listed here, most of which are not. I will continue to write articles about the most interesting aspects of these system, but let me know what else you want to know about!

    Please let me know if you have any questions about what’s here. Thanks for reading!

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