The basic structural unit in a compact bone is known as the osteon (or Haversian system). The position of lacune differs in each type of bone. The dense bones that can withstand high compressional forces are known as the compact bone whereas the bones with a highly porous structure that supports weight during the weight shift are known as the spongy or cancellous bone. The bones are of two types: compact bones and spongy bones. Figure 4: Osteocytes in the lacuna and lacuna-canalicular network. Also, the lacuna-canalicular system enables the transfer of biochemical signals between the osteocytes, thus, forming a functional network. This fluid passes through the lacuna-canalicular space and immerses the osteocyte, supplying nutrients and oxygen required to maintain the osteocyte’s cell viability in a calcified environment. The canaliculi are filled with fluid known as canalicular fluid (or bone fluid). ![]() This lacuna-canalicular network connects cells on the bone surface with the vasculature. Collectively, the osteocyte lacunae and canaliculi form the lacuna-canalicular system. The cell body of each osteocyte is enclosed in a lacuna having a diameter of 15–20 μm in diameter, while the dendritic projections of the osteocyte pass canaliculi (250–300 nm in diameter). These canaliculi serve the function of transportation of nutrients and waste and communicating with other osteocytes.Įach lacuna contains one osteocyte cell. ![]() The dendritic projections of the osteocyte cells pass through tiny channels called canaliculi (or small canals). Credit: (Paxton et al., 2021).īone cells that become surrounded by the bone matrix and are located in cavities called lacunae are the osteocytes, which are stellate-shaped due to the several dendritic projections. Figure 3: Osteocyte in lacuna with canaliculi. Thus, the lacunae of the osseous tissue contain osteocytes that prevent them from calcification. Within the calcified matrix, the space occupied by the osteocytes is called lacuna. Osteocytes form almost 95% of the bone tissue. Osteocytes are the stellate-shaped bone cells that maintain bone tissue. Osteoblasts in the organic matrix transform into osteocytes. The osteoid is eventually calcified or undergoes ossification. They are the cells that line the bone surface and are responsible for collagen and organic matrix (i.e., osteoid) of the bone secretion. Osteoblasts originate from osteoprogenitor cells. Osteoclasts are the bone cells that break down the bone tissues and function to repair and remodel the bone tissue. If a lacuna pertains to a gap, what can we find in a lacuna, particularly in bones and in cartilages? Lacuna in bones Use of drug to avoid or alleviate withdrawal symptoms.Now that we know the definition of lacuna, let’s find out about the structures present in a lacuna. Continued use of drug despite knowledge of its harm.ĩ. Sacrifice of other activities or things for the drug.Ħ. Intoxication or withdrawal symptoms at inappropriate times.ĥ. Excessive time spent in procuring drug.Ĥ. ![]() Unsuccessful attempts to quit, persistent desire to use the agent, craving for drug.ģ. Taking the drug more often or in larger amounts than intended.Ģ. (3) A neurobehavioural syndrome with genetic and environmental influences that results in psychological dependence on the use of substances for their psychic effects addiction is characterised by compulsive use despite harm.ġ. (2) A disorder involving use of opioids wherein there is a loss of control, compulsive use, and continued use despite adverse social, physical, psychological, occupational, or economic consequences. Risk of addiction Cocaine, amphetamines > opiates & nicotine > alcohol, benzodiazepine, barbiturates > cannabis, hallucinogens, caffeine. Substance abuse (1) A physiologic, physical, or psychological state of dependency on a substance-or pattern of compulsive use-which is characterised by tolerance, craving, and a withdrawal syndrome when intake of the substance is reduced or stopped the most common addictions are to alcohol, caffeine, cocaine, heroin, marijuana, nicotine, amphetamines. In sexual addiction, it is not the activity that is addicting, but rather the object toward which the activity is directed. Sexology A state characterised by habitually and compulsively engaging in stereotyped activity regardless of potentially negative consequences. Addiction Psychiatry A preoccupation with and compulsive use of a substance despite recurrent adverse consequences addiction often involves a loss of control and increased tolerance, and may be associated with a biological predisposition. The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company.
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