Terminology
Questions Received:
Responses:
What are morbidity, pathogenesis, and aetiology?
20th March 1999
Morbidity - this is a medical term derived from the Latin word morbidus, which means diseased. So morbidity is the state of being diseased, or being ill. The same word can be applied to the occurrence of illness in a community or population. In everyday English, the word morbid is applied to people who are pre-occupied with rather gloomy or unhealthy thoughts. morbidity - this is a medical term derived from the Latin word morbidus, which means diseased. So morbidity is the state of being diseased, or being ill. The same word can be applied to the occurrence of illness in a community or population. In everyday English, the word morbid is applied to people who are pre-occupied with rather gloomy or unhealthy thoughts. morbidity - this is a medical term derived from the Latin word morbidus, which means diseased. So morbidity is the state of being diseased, or being ill. The same word can be applied to the occurrence of illness in a community or population. In everyday English, the word morbid is applied to people who are pre-occupied with rather gloomy or unhealthy thoughts.
Pathogenesis - from the Greek pathos, which means suffering, and genesis, to be born or to originate. It is used in relation to the origin and progression of a disease. So, for example, the pathogenesis of an infectious disease includes the causative organism such as a bacterium or virus and the course of the fever and immune response that follows. pathogenesis - from the Greek pathos, which means suffering, and genesis, to be born or to originate. It is used in relation to the origin and progression of a disease. So, for example, the pathogenesis of an infectious disease includes the causative organism such as a bacterium or virus and the course of the fever and immune response that follows. pathogenesis - from the Greek pathos, which means suffering, and genesis, to be born or to originate. It is used in relation to the origin and progression of a disease. So, for example, the pathogenesis of an infectious disease includes the causative organism such as a bacterium or virus and the course of the fever and immune response that follows.
Aetiology - from the Greek aitia, cause, and logos, discourse. Aetiology is the study of the causes of disease. (In American textbooks this is spelt etiology.) aetiology - from the Greek aitia, cause, and logos, discourse. Aetiology is the study of the causes of disease. (In American textbooks this is spelt etiology.) aetiology - from the Greek aitia, cause, and logos, discourse. Aetiology is the study of the causes of disease. (In American textbooks this is spelt etiology.)
If you are studying a health care subject or biology for the first time, it will be valuable to have a suitable medical, nursing, or science dictionary close to hand so that you can look up new words as you encounter them.
What are osmosis and filtration?
7th April 1999
Osmosis
Osmosis is the passage of solvent molecules - in biological systems this usually means water - from a weak (dilute) solution to a stronger (more concentrated) solution through a semipermeable membrane. Semipermeable means that the membrane is selective - it only allows molecules below a certain size to pass through. So it allows the water molecules to pass through, but not larger solute molecules such as proteins. The presence of greater numbers of solute molecules on the more concentrated side of the membrane seems to 'attract' the water molecules to them from the other side of the membrane. So the energy driving this form of movement is provided by the differences in concentration across the membrane. Body cells are surrounded by just such a selectively permeable membrane: the plasma membrane allows water molecules to pass through from the side with the more dilute solution to the side where the solution is more concentrated, but restricts and controls the movement of larger molecules.
Filtration
Generally this means the separation of substances from a liquid mixture, using a porous material which traps the larger substances on one side whilst allowing the remainder to pass through. So for example you can filter muddy water by passing it through a filter paper - the mud particles are trapped on the surface of the paper and the water passes through. The term is also applied to other situations, such as the filtering of light and other forms of radiation into different wavelengths. In biological systems, filtration usually involves the separation of different molecules in fluids. Thus, the nephrons of the kidney filter the blood, allowing certain molecules to pass through into the tubule of the nephron, whilst preventing the passage of blood cells and plasma proteins. For filtration to work, there has to be some motivating force at work, and in the case of the kidneys it is the pressure of the blood in the vessels that facilitates filtration. This filtration pressure has to overcome any osmotic differences that may exist between the blood in the vessels and the more dilute filtrate in the tubules.
How can one define what fluid aspiration is?
9th May 1999
Fluid aspiration usually means the withdrawal of fluid from a body cavity by suction. The word aspiration comes from the Latin aspirare, to breathe upon. So for example, if too much fluid has accumulated in the pleural cavity around the lung, the excess is removed by aspiration. A sample of the aspirate may be sent for cytological studies to enable a diagnosis to be made.
Other examples of aspiration:
Aspiration of bursal fluid from the knee joint if conservative measures to treat bursitis have been unsuccessful
Aspiration of a hydrocele (fluid accumulation in the scrotum), if conservative measures are inappropriate
Aspiration of gastric contents via a naso-gastric tube e.g. to treat postoperative paralytic ileus
(One of the main reasons for fasting before a general anaesthetic is to reduce the risk of stomach contents being regurgitated and inhaled - aspirated - before endotracheal intubation or a pharyngeal mask has been inserted to protect the person's airway. Someone with a hiatus hernia can be at increased risk of this particular problem occurring. Aspiration of acid stomach contents into the lungs will produce aspiration pneumonia and/or a pulmonary abcess. Stringent precautions are therefore taken during the pre-operative stages to lessen the risk of these occurring.)
What is derivation of Cadaver?
15th May 1999
Cadaver is derived from the Latin cadere, to fall. It is now used particularly in the context of human bodies used for dissection.
Could you please define polycythaemia in chronic obstructive pulmonary disease.
24th October 1999
The term polycythaemia is applied to an increase in the number of red blood cells in the circulating blood. Any chronic pulmonary disease which alters ventilation-perfusion relationships or seriously impairs gas diffusion may produce chronic hypoxia - insufficient oxygen being carried by the blood to the tissues. Homeostatic processes redress the balance by causing more red cells to be added to the circulation than are being removed through natural wastage, and in this way enable the blood to carry more oxygen. A similar response occurs if you move to a higher altitude and live there for a while.
What is Chronic Medullary Infarction?
22nd June 2000
The term ‘medulla’ is used in several contexts. It is used to refer to the marrow cavity within bones, and to the more central region within organs such as the kidneys, adrenal glands, and lymph nodes. It is also used in relation to the medulla oblongata, a part of the brainstem situated between the upper part of the spinal cord and the pons of the brain. Infarction means that a region of tissue within the body has died, often because it has been deprived of its blood supply. Chronic means long-lasting. So, putting it all together, ‘chronic medullary infarction’ would be used to describe cell death in the medullary region of a bone or organ, or perhaps in part of the brain, and which has been continuing for some time.
I am currently trying to write an essay on wound care and have searched everywhere for a reference on the definition of an ulcer, ie a wound lasting for more that six weeks, and cannot find one anywhere.
9th August 2000
The word ulcer goes back a long way, being derived originally from the Latin for wound and then reaching Middle English via Old French. It is always fascinating to look into the origin of medical and nursing terms - sometimes it feels akin to making an archeological dig! - but you may not be able to find an up-to-date discussion about the ‘meaning’ of ulcer to which you can make a reference. It is one of those words which has become deeply embedded in everyday language, and there already seems to be a general consensus about how it should be used. Most people are prepared to accept that an ulcer is a crater-like lesion of the skin or an internal mucous membrane that may be linked with a variety of physical, inflammatory, infectious, and malignant factors. There are of course many different named types of ulcer, ranging from external ulcers such as pressure sores and leg ulcers to internal ulcers such as mouth ulcers, gastric ulcers, peptic ulcers and so on. Therefore for your essay, it should be acceptable to quote one of the general dictionary definitions of ‘ulcer’ (giving the source) and take it from there, focusing on the particular types of ulcers that are of relevance to your main theme of wound care. I have looked at several dictionary definitions, but none of them mentions that a period of, for example, 6 weeks should elapse before the term ulcer is applied, even though the chronic nature of an ulcer is one of its main characteristics. It will be worthwhile for you to introduce that element yourself and explain your reasons for doing so.
What does an increased ESR mean?
12th July 2001
ESR stands for erythrocyte sedimentation rate. This is a test carried out on a blood sample in the laboratory - it is a measure of how quickly the red blood cells settle in a narrow column. After 1 hour, the length of the clear serum above the red cells is measured. If the red cells settle more quickly than usual, this is an indication that an inflammatory process is occurring somewhere in the body. (Inflammation is a response by living tissues to infection, injury, and irritation.) The ESR test does not by itself give a clear diagnosis of what may be wrong, but it does help in reaching a diagnosis by showing whether or not inflammation is present.