Lymph capillaries or lymphatic capillaries are tiny, thin-walled microvessels located in the spaces between cells which serve to drain and process extracellular fluid. Upon entering the lumen of a lymphatic capillary, the collected fluid and associated cells is known as lymph; each lymphatic capillary carries lymph into a lymphatic vessel, which in turn connects to a lymph node. Lymph is returned to the venous circulation. Lymphatic capillaries are larger in diameter than blood capillaries, have closed ends, their unique structure permits interstitial fluid to flow into them but not out. The ends of the endothelial cells that make up the wall of a lymphatic capillary overlap; when pressure is greater in the interstitial fluid than in lymph, the cells separate like the opening of a one-way swinging door, interstitial fluid enters the lymphatic capillary. When pressure is greater inside the lymphatic capillary, the cells adhere more and lymph cannot escape back into interstitial fluid. Attached to the lymphatic capillaries are anchoring filaments, which contain elastic fibers.
They extend out from the lymphatic capillary, attaching lymphatic endothelial cells to surrounding tissues. When excess interstitial fluid accumulates and causes tissue swelling, the anchoring filaments are pulled, making the openings between cells larger so that more fluid can flow into the lymphatic capillary. Lymph capillaries have a greater internal oncotic pressure than blood capillaries, due to the greater concentration of plasma proteins in the lymph
Chylomicrons are lipoprotein particles that consist of triglycerides, phospholipids and proteins. They transport dietary lipids from the intestines to other locations in the body. Chylomicrons are one of the five major groups of lipoproteins: chylomicrons low-density lipoprotein, intermediate-density lipoprotein, low-density lipoprotein, high-density lipoprotein, that enable fats and cholesterol to move within the water-based solution of the bloodstream. Chylomicrons transport lipids absorbed from the intestine to adipose and skeletal muscle tissue, where their triglyceride components are hydrolyzed by the activity of the lipoprotein lipase, allowing the released free fatty acids to be absorbed by the tissues; when a large portion of the triacylglycerol core have been hydrolyzed, chylomicron remnants are formed and are taken up by the liver, thereby transferring dietary fat to the liver. Chylomicrons are formed in the endoplasmic reticulum in the absorptive cells of the small intestine; the villi, lined with the microvilli of the brush border, provide a lot of surface area for absorption.
Newly formed chylomicrons are secreted through the basolateral membrane into the lacteals, where they join lymph to become chyle. The lymphatic vessels carry the chyle to the venous return of the systemic circulation. From there the chylomicrons supply the tissue with fat absorbed from the diet. Thus, unlike the saccharides and amino acids that digestion liberates from the carbohydrates and proteins of the diet, the lipids from the diet bypass the hepatic portal system, meaning the liver does not get "first crack" at them. There are three stages in the chylomicron's "lifecycle": Nascent chylomicron Mature chylomicron Chylomicron remnant Triglycerides are emulsified by bile and hydrolyzed by the enzyme lipase, resulting in a mixture of fatty acids and monoglycerides; these pass from the intestinal lumen into the enterocyte, where they are re-esterified to form triglycerides. The triglycerides are combined with phospholipids, cholesteryl esters, apolipoprotein B-48 to form a nascent chylomicron.
These are released by exocytosis from the enterocytes into the lacteals, lymphatic vessels originating in the villi of the small intestine, are secreted into the bloodstream at the thoracic duct's connection with the left subclavian vein. Nascent chylomicrons are composed of triglycerides and contain some cholesterol and cholesteryl esters; the main apolipoprotein component is apolipoprotein B-48. While circulating in blood, chylomicrons exchange components with high-density lipoproteins; the HDL donates apolipoprotein C-II and apolipoprotein E to the nascent chylomicron and, converts it to a mature chylomicron. APOC2 is the coenzyme for lipoprotein lipase activity. Once triglyceride stores are distributed, the chylomicron returns APOC2 to the HDL, thus, becomes a chylomicron remnant, now only 30–50 nm. APOB48 and APOE are important to identify the chylomicron remnant in the liver for endocytosis and breakdown
Diffusion is the net movement of molecules or atoms from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in chemical potential of the diffusing species. A gradient is the change in the value of a quantity e.g. concentration, pressure, or temperature with the change in another variable distance. A change in concentration over a distance is called a concentration gradient, a change in pressure over a distance is called a pressure gradient, a change in temperature over a distance is called a temperature gradient; the word diffusion derives from the Latin word, which means "to spread way out.” A distinguishing feature of diffusion is that it depends on particle random walk, results in mixing or mass transport without requiring directed bulk motion. Bulk motion, or bulk flow, is the characteristic of advection; the term convection is used to describe the combination of both transport phenomena. An example of a situation in which bulk motion and diffusion can be differentiated is the mechanism by which oxygen enters the body during external respiration known as breathing.
The lungs are located in the thoracic cavity, which expands as the first step in external respiration. This expansion leads to an increase in volume of the alveoli in the lungs, which causes a decrease in pressure in the alveoli; this creates a pressure gradient between the air outside the body at high pressure and the alveoli at low pressure. The air moves down the pressure gradient through the airways of the lungs and into the alveoli until the pressure of the air and that in the alveoli are equal i.e. the movement of air by bulk flow stops once there is no longer a pressure gradient. The air arriving in the alveoli has a higher concentration of oxygen than the “stale” air in the alveoli; the increase in oxygen concentration creates a concentration gradient for oxygen between the air in the alveoli and the blood in the capillaries that surround the alveoli. Oxygen moves by diffusion, down the concentration gradient, into the blood; the other consequence of the air arriving in alveoli is that the concentration of carbon dioxide in the alveoli decreases.
This creates a concentration gradient for carbon dioxide to diffuse from the blood into the alveoli, as fresh air has a low concentration of carbon dioxide compared to the blood in the body. The pumping action of the heart transports the blood around the body; as the left ventricle of the heart contracts, the volume decreases, which increases the pressure in the ventricle. This creates a pressure gradient between the heart and the capillaries, blood moves through blood vessels by bulk flow down the pressure gradient; as the thoracic cavity contracts during expiration, the volume of the alveoli decreases and creates a pressure gradient between the alveoli and the air outside the body, air moves by bulk flow down the pressure gradient. The concept of diffusion is used in: physics, biology, sociology and finance. However, in each case, the object, undergoing diffusion is “spreading out” from a point or location at which there is a higher concentration of that object. There are two ways to introduce the notion of diffusion: either a phenomenological approach starting with Fick's laws of diffusion and their mathematical consequences, or a physical and atomistic one, by considering the random walk of the diffusing particles.
In the phenomenological approach, diffusion is the movement of a substance from a region of high concentration to a region of low concentration without bulk motion. According to Fick's laws, the diffusion flux is proportional to the negative gradient of concentrations, it goes from regions of higher concentration to regions of lower concentration. Sometime various generalizations of Fick's laws were developed in the frame of thermodynamics and non-equilibrium thermodynamics. From the atomistic point of view, diffusion is considered as a result of the random walk of the diffusing particles. In molecular diffusion, the moving molecules are self-propelled by thermal energy. Random walk of small particles in suspension in a fluid was discovered in 1827 by Robert Brown; the theory of the Brownian motion and the atomistic backgrounds of diffusion were developed by Albert Einstein. The concept of diffusion is applied to any subject matter involving random walks in ensembles of individuals. Biologists use the terms "net movement" or "net diffusion" to describe the movement of ions or molecules by diffusion.
For example, oxygen can diffuse through cell membranes so long as there is a higher concentration of oxygen outside the cell. However, because the movement of molecules is random oxygen molecules move out of the cell; because there are more oxygen molecules outside the cell, the probability that oxygen molecules will enter the cell is higher than the probability that oxygen molecules will leave the cell. Therefore, the "net" movement of oxygen molecules is into the cell. In other words, there is a net movement of oxygen molecules down the concentration gradient. In the scope of time, diffusion in solids was used. For example, Pliny the Elder had described the cementation process, which produces steel from the element iron through carbon diffusion. Another example is well known for many centuries, the diffusion of colors of stained glass or earthenware and Chinese ceramics. In modern science, the first systematic experimental study of di
Anatomical terminology is a form of scientific terminology used by anatomists and health professionals such as doctors. Anatomical terminology uses many unique terms and prefixes deriving from Ancient Greek and Latin; these terms can be confusing to those unfamiliar with them, but can be more precise, reducing ambiguity and errors. Since these anatomical terms are not used in everyday conversation, their meanings are less to change, less to be misinterpreted. To illustrate how inexact day-to-day language can be: a scar "above the wrist" could be located on the forearm two or three inches away from the hand or at the base of the hand. By using precise anatomical terminology such ambiguity is eliminated. An international standard for anatomical terminology, Terminologia Anatomica has been created. Anatomical terminology has quite regular morphology, the same prefixes and suffixes are used to add meanings to different roots; the root of a term refers to an organ or tissue. For example, the Latin names of structures such as musculus biceps brachii can be split up and refer to, musculus for muscle, biceps for "two-headed", brachii as in the brachial region of the arm.
The first word describes what is being spoken about, the second describes it, the third points to location. When describing the position of anatomical structures, structures may be described according to the anatomical landmark they are near; these landmarks may include structures, such as the umbilicus or sternum, or anatomical lines, such as the midclavicular line from the centre of the clavicle. The cephalon or cephalic region refers to the head; this area is further differentiated into the cranium, frons, auris, nasus and mentum. The neck area is called cervical region. Examples of structures named according to this include the frontalis muscle, submental lymph nodes, buccal membrane and orbicularis oculi muscle. Sometimes, unique terminology is used to reduce confusion in different parts of the body. For example, different terms are used when it comes to the skull in compliance with its embryonic origin and its tilted position compared to in other animals. Here, Rostral refers to proximity to the front of the nose, is used when describing the skull.
Different terminology is used in the arms, in part to reduce ambiguity as to what the "front", "back", "inner" and "outer" surfaces are. For this reason, the terms below are used: Radial referring to the radius bone, seen laterally in the standard anatomical position. Ulnar referring to the ulna bone, medially positioned when in the standard anatomical position. Other terms are used to describe the movement and actions of the hands and feet, other structures such as the eye. International morphological terminology is used by the colleges of medicine and dentistry and other areas of the health sciences, it facilitates communication and exchanges between scientists from different countries of the world and it is used daily in the fields of research and medical care. The international morphological terminology refers to morphological sciences as a biological sciences' branch. In this field, the form and structure are examined as well as the changes or developments in the organism, it is functional.
It covers the gross anatomy and the microscopic of living beings. It involves the anatomy of the adult, it includes comparative anatomy between different species. The vocabulary is extensive and complex, requires a systematic presentation. Within the international field, a group of experts reviews and discusses the morphological terms of the structures of the human body, forming today's Terminology Committee from the International Federation of Associations of Anatomists, it deals with the anatomical and embryologic terminology. In the Latin American field, there are meetings called Iberian Latin American Symposium Terminology, where a group of experts of the Pan American Association of Anatomy that speak Spanish and Portuguese and studies the international morphological terminology; the current international standard for human anatomical terminology is based on the Terminologia Anatomica. It was developed by the Federative Committee on Anatomical Terminology and the International Federation of Associations of Anatomists and was released in 1998.
It supersedes Nomina Anatomica. Terminologia Anatomica contains terminology for about 7500 human gross anatomical structures. For microanatomy, known as histology, a similar standard exists in Terminologia Histologica, for embryology, the study of development, a standard exists in Terminologia Embryologica; these standards specify accepted names that can be used to refer to histological and embryological structures in journal articles and other areas. As of September 2016, two sections of the Terminologia Anatomica, including central nervous system and peripheral nervous system, were merged to form the Terminologia Neuroanatomica; the Terminologia Anatomica has been perceived with a considerable criticism regarding its content including coverage and spelling mistakes and errors. Anatomical terminology is chosen to highlight the relative location of body structures. For instance, an anatomist might describe one band of tissue as "inferior to" another or a physician might describe a tumor as "superficial to" a deeper body structure.
Anatomical terms used to describe location
A lacteal is a lymphatic capillary that absorbs dietary fats in the villi of the small intestine. Triglycerides are emulsified by bile and hydrolyzed by the enzyme lipase, resulting in a mixture of fatty acids, di- and monoglycerides; these pass from the intestinal lumen into the enterocyte, where they are re-esterified to form triglyceride. The triglyceride is combined with phospholipids, cholesterol ester, apolipoprotein B48 to form chylomicrons; these chylomicrons pass into the lacteals, forming a milky substance known as chyle. The lacteals merge to form larger lymphatic vessels that transport the chyle to the thoracic duct where it is emptied into the bloodstream at the subclavian vein. At this point, the fats are in the bloodstream in the form of chylomicrons. Once in the blood, chylomicrons are subject to delipidation by lipoprotein lipase. Enough lipid has been lost and additional apolipoproteins gained, that the resulting particle can be taken up by the liver. From the liver, the fat released from chylomicron remnants can be re-exported to the blood as the triglyceride component of low-density lipoproteins.
Low-density lipoproteins are subject to delipidation by vascular lipoprotein lipase, deliver fats to tissues throughout the body. In particular, the released fatty acids can be stored in adipose cells as triglycerides; as triglycerides are lost from low-density lipoproteins, the lipoprotein particles become smaller and denser and become low-density lipoproteins. A great deal has been written about low-density lipoproteins because they are thought to be atherogenic. Note that in contrast to any other route of absorption from the small intestine, the lymphatic system avoids first pass metabolism. Histology image: 11705loa – Histology Learning System at Boston University - "117. Digestive System: Alimentary Canal jejunum, central lacteals "
In biology, tissue is a cellular organizational level between cells and a complete organ. A tissue is an ensemble of similar cells and their extracellular matrix from the same origin that together carry out a specific function. Organs are formed by the functional grouping together of multiple tissues; the English word "tissue" is derived from the French "tissu", meaning something, "woven", from the verb tisser, "to weave". The study of human and animal tissues is known as histology or, in connection with disease, histopathology. For plants, the discipline is called plant anatomy; the classical tools for studying tissues are the paraffin block in which tissue is embedded and sectioned, the histological stain, the optical microscope. In the last couple of decades, developments in electron microscopy, immunofluorescence, the use of frozen tissue sections have enhanced the detail that can be observed in tissues. With these tools, the classical appearances of tissues can be examined in health and disease, enabling considerable refinement of medical diagnosis and prognosis.
Animal tissues are grouped into four basic types: connective, muscle and epithelial. Collections of tissues joined in structural units to serve a common function compose organs. While all eumetazoan animals can be considered to contain the four tissue types, the manifestation of these tissues can differ depending on the type of organism. For example, the origin of the cells comprising a particular tissue type may differ developmentally for different classifications of animals; the epithelium in all birds and animals is derived from the ectoderm and endoderm, with a small contribution from the mesoderm, forming the endothelium, a specialized type of epithelium that composes the vasculature. By contrast, a true epithelial tissue is present only in a single layer of cells held together via occluding junctions called tight junctions, to create a selectively permeable barrier; this tissue covers all organismal surfaces that come in contact with the external environment such as the skin, the airways, the digestive tract.
It serves functions of protection and absorption, is separated from other tissues below by a basal lamina. Connective tissues are fibrous tissues, they are made up of cells separated by non-living material, called an extracellular matrix. This matrix can be rigid. For example, blood contains plasma as its matrix and bone's matrix is rigid. Connective tissue holds them in place. Blood, tendon, ligament and areolar tissues are examples of connective tissues. One method of classifying connective tissues is to divide them into three types: fibrous connective tissue, skeletal connective tissue, fluid connective tissue. Muscle cells form the active contractile tissue of the body known as muscle tissue or muscular tissue. Muscle tissue functions to produce force and cause motion, either locomotion or movement within internal organs. Muscle tissue is separated into three distinct categories: visceral or smooth muscle, found in the inner linings of organs. Cells comprising the central nervous system and peripheral nervous system are classified as nervous tissue.
In the central nervous system, neural tissues form spinal cord. In the peripheral nervous system, neural tissues form the cranial nerves and spinal nerves, inclusive of the motor neurons; the epithelial tissues are formed by cells that cover the organ surfaces, such as the surface of skin, the airways, the reproductive tract, the inner lining of the digestive tract. The cells comprising an epithelial layer are linked via tight junctions. In addition to this protective function, epithelial tissue may be specialized to function in secretion and absorption. Epithelial tissue helps to protect organs from microorganisms and fluid loss. Functions of epithelial tissue: The cells of the body's surface form the outer layer of skin. Inside the body, epithelial cells form the lining of the mouth and alimentary canal and protect these organs. Epithelial tissues help in absorption of water and nutrients. Epithelial tissues help in the elimination of waste. Epithelial tissues hormones in the form of glands; some epithelial tissue perform secretory functions.
They secrete a variety of substances such as sweat, enzymes, etc. There are many kinds of epithelium, nomenclature is somewhat variable. Most classification schemes combine a description of the cell-shape in the upper layer of the epithelium with a word denoting the number of layers: either simple or stratified. However, other cellular features, such as cilia may be described in the classification system; some common kinds of epithelium are listed below: Simple squamous epithelium Stratified squamous epithelium Simple cuboidal epithelium Transitional epithelium Pseudostratified columnar epithelium Columnar epithelium Glandular epithelium Ciliated columnar epithelium In plant anatomy, tissues are categorized broadly into three tissue systems: the epidermis, the ground tissue, the vascular tissue. Epidermis - Cells forming the outer surface of the leaves and of the young plant body. Vascular tissue - The primary components of vascular tissue are the xylem and phloem; these transport nutrients internally.
Ground tissue - Ground tissue is less differentiated than other tissues. Ground tis
The Lympha is an ancient Roman deity of fresh water. She is one of twelve agricultural deities listed by Varro as "leaders" of Roman farmers, because "without water all agriculture is dry and poor." The Lymphae are connected to Fons, meaning "Source" or "Font," a god of fountains and wellheads. Lympha represents a "functional focus" of fresh water, according to Michael Lipka's conceptual approach to Roman deity, or more moisture. Vitruvius preserves some of her associations in the section of his work On Architecture in which he describes how the design of a temple building should reflect the nature of the deity to be housed therein: The character of the Corinthian order seems more appropriate to Venus, Flora and the Nymphs of the Fountains; the name Lympha is equivalent to, but not interchangeable with nympha, "nymph." One dedication for restoring the water supply was made nymphis lymphisque augustis, "for the nymphs and august lymphae," distinguishing the two as does a passage from Augustine of Hippo.
In poetic usage, lymphae as a common noun, plural or less singular, can mean a source of fresh water, or "water". When she appears in a list of proper names for deities, Lympha is seen as an object of religious reverence embodying the divine aspect of water. Like several other nature deities who appear in both the singular and the plural, she has both a unified and a multiple aspect, she was the appropriate deity to pray to for maintaining the water supply, in the way that Liber provided wine or Ceres bread. The origin of the word lympha is obscure, it may have been lumpa or limpa, related to the adjective limpidus meaning "clear, transparent" applied to liquids. An intermediate form lumpha is found; the spelling seems to have been influenced by the Greek word νύμφα nympha, as the upsilon and phi are transcribed into Latin as u or y and ph or f. That Lympha is an Italic concept is indicated by the Oscan cognate diumpā-, with a characteristic alternation of d for l; these goddesses appear on the Tabula Agnonensis as one of 17 Samnite deities, who include the equivalents of Flora and Venus, as well as several of the gods on Varro's list of the 12 agricultural deities.
On the Oscan tablet, they appear in a group of deities. In the Etruscan-based cosmological schema of Martianus Capella, the Lymphae are placed in the second of 16 celestial regions, with Jupiter, Mars, the Military Lar, Juno and the obscure Italo-Etruscan Novensiles. A 1st-century A. D. dedication was made to the Lymphae jointly with Diana. The Italic lymphae were connected with healing cults. Juturna, called a "nymph," is identified by Varro as Lympha: "Juturna is the Lympha who aids: therefore many ailing people on account of her name customarily seek out this water", with a play on the name Iu-turna and the verb iuvare, "to help, aid." Juturna's water shrine was a spring-fed lacus in the forum which attracted cure-seekers, Propertius connected its potency to Lake Albano and Lake Nemi, where the famous sanctuary of Diana Nemorensis was located. Juturna's cult, which Servius identifies as a fons, was maintained to ensure the water supply, she was the mother of the deity Fons. In Cisalpine Gaul, an inscription links the Lymphae to the Vires, " Powers, Vigor", personified as a set of masculine divinities, a connection that in his monumental work Zeus Arthur Bernard Cook located in the flowing or liquid aspect of the Lymphae as it relates to the production of seminal fluid.
As a complement to the Vires, the Lymphae and the nymphs with whom they became so identified embody the urge to procreate, thus these kinds of water deities are associated with marriage and childbirth. When Propertius alludes to the story of how Tiresias spied the virgin goddess Pallas Athena bathing, he plays on the sexual properties of lympha in advising against theophanies obtained against the will of the gods: "May the gods grant you other fountains: this liquid flows for girls only, this pathless trickle of a secret threshold."The Augustan poets play with the ambiguous dual meaning of lympha as both "water source" and "nymph". In the poetry of Horace, lymphae work and make noise; some textual editors have responded to this personification by emending manuscript readings of lymphae to nymphae. When the first letter of a form of -ympha is obliterated or indistinct in an inscription, the word is taken as nympha instead of the less common lympha. In the religions of ancient Greece and the Celtic territories, water goddesses are sources of inspiration or divine revelation, which may have the appearance of madness or frenzy.
In Greek, "nympholepsy" was "a heightening of awareness and elevated verbal skills" resulting from the influence of the nymphs on an individual. The term meant a physical snatching or abduction of a person by the nymphs, as in the myth of Hylas, by extension became a euphemism or metaphor for death, as evidenced by both Greek and Roman epitaphs. A person, a religious devotee of the nymphs might be called a "nympholept."The Latin verb lympho, lymphare meant "