Dead Space: From 1 Different Sources
Gas exchange only occurs in the terminal parts of the pulmonary airways (see LUNGS). That portion of each breath that is taken into the lungs but does not take part in gas exchange is known as dead space. Anatomical dead space describes air in the airways up to the terminal BRONCHIOLES. Physiological dead space also includes gas in alveoli (air sacs) which are unable to take part in gas exchange because of structural abnormalities or disease.
A medical specialty dealing with the physiological, PSYCHOLOGICAL and pathological consequences of space ?ight in which the body has to cope with unusual variations in gravitational forces, including weightlessness, a constricted environment, prolonged close contact with work colleagues in very demanding technical circumstances, and sustained periods of emotional pressure including fear. Enormous progress has been made in providing astronauts with as normal an environment as possible, and they have to undergo prolonged physical and mental training before embarking on space travel.... space medicine
The space between the arachnoid and the pia mater – two of the membranes covering the BRAIN. (See also MENINGES.)... subarachnoid space
See RAYNAUD’S DISEASE.... dead fingers
Practically, only three methods have been used from the earliest times: burial, embalming and cremation. Burial is perhaps the earliest and most primitive method. It was customary to bury the bodies of the dead in consecrated ground around churches up until the earlier half of the 19th century, when the utterly insanitary state of churchyards led to legislation for their better control. Burials in Britain take place usually upon production of a certi?cate from a registrar of deaths, to whom notice of the death, accompanied by a medical certi?cate, must be given without delay by the nearest relatives.
When a death occurs at sea, the captain of the ship has authority to permit burial at sea. If, however, there are any doubts about cause of death, the captain may decide to preserve the body and refer the case to the relevant authorities at the next port of call.
Embalming is still used occasionally. The process consists in removing the internal organs through small openings, and ?lling the body cavities with various aromatics of antiseptic power – the skin being swathed in bandages or otherwise protected from the action of the air. Bodies are also preserved by injecting the blood vessels with strong antiseptics such as perchloride of mercury.
Cremation or incineration of the body is now the commonest method of disposal of the dead in the UK, where land for burials is increasingly scarce; today it accounts for around 75 per cent of disposals. The process of incineration takes 1–2 hours. Something in the range of 2·3 to 3·2 kg (5–7 lbs) of ash result from the combustion of the body, and there is no admixture with that from the fuel.
Cremation of a body means that it is almost impossible to conduct any meaningful forensic tests should any subsequent doubts be raised about the cause of death. So, before cremation can take place, two doctors have to sign the cremation forms. The ?rst is usually the doctor who was caring for the patient at the time of death – an important exception being cases of sudden death, when the coroner holds an inquest into the cause and authorises the necessary approval for cremation. In 1999, fewer than 3,500 deaths were certi?ed following a post-mortem, out of a total number of deaths in England and Wales of more than 556,000. When the coroner is not involved, the second doctor must have been quali?ed for ?ve years; he or she must be unconnected with the patient’s care and not linked professionally with the ?rst doctor. (For example, if the ?rst doctor is a general practitioner – as in the majority of cases they are – the second doctor should be from another practice.) Before signing the cremation certi?cate the second doctor must conduct an external examination of the dead person and discuss the circumstances of death with the ?rst doctor.
The two cremation forms are then inspected by crematorium medical referees who must be satis?ed that the cause of death has de?nitely been ascertained. The present death and cremation certi?cation system has been in place in the UK for many years – the legislative framework for cremation was set up in 1902 – and death certi?cation procedures were last reviewed by the government-appointed Brodrick committee in 1971, with no fundamental changes proposed. The case of Harold Shipman, a general practitioner convicted of murdering more than 15 patients, and suspected of murdering many more, has revealed serious weaknesses in the certi?cation system. A comprehensive review of the present procedures was in place at the time of writing (2004).... dead, disposal of the
The name given to the region behind the knee. The muscles attached to the bones immediately above and below the knee bound a diamond-shaped space through which pass the main artery and vein of the limb (known in this part of their course as the popliteal artery and vein); the tibial and common peroneal nerves (which continue the sciatic nerve from the thigh down to the leg); the external saphenous vein; and several small nerves and lymphatic vessels. The muscles – which bound the upper angle of the space and which are attached to the leg bones by strong prominent tendons – are known as the hamstrings. The lower angle of the space lies between the two heads of the gastrocnemius muscle, which makes up the main bulk of the calf of the leg.... popliteal space
see parapharyngeal space.... lateral parapharyngeal space
(lateral parapharyngeal space) the region at the side of the *pharynx. Infection in this space can result in a parapharyngeal abscess. It is also a site where tumours can develop.... parapharyngeal space
see Virchow–Robin spaces.... perivascular spaces
see nasopharynx.... postnasal space
the region between the posterior parietal *peritoneum and the front of the *lumbar vertebrae. It contains important structures, including the kidneys, adrenal glands, pancreas, lumbar spinal nerve roots, sympathetic ganglia and nerves, and the abdominal *aorta and its major branches.... retroperitoneal space
the region behind the *pharynx and in front of the bones of the neck. Infection in this space can result in a retropharyngeal abscess.... retropharyngeal space
a custom-made orthodontic appliance that maintains an existing space in the dentition to allow a permanent tooth to erupt into the space. It may be removable or cemented into place.... space maintainer
n. a plastic container with a mouthpiece at one end and a hole for an aerosol inhaler at the other. The dose from the inhaler is sprayed into the spacer, from which it can be inhaled without needing to coordinate breathing. It is particularly useful for babies and small children who do not have this coordination. Paediatric spacers also have a small mask that fits onto the mouthpiece of the spacer and is placed over the child’s nose and mouth. Spacers help to deliver a greater proportion of the dose to the airways while reducing the proportion absorbed into the body (which is the usual cause of unwanted side-effects)... spacer
(perivascular spaces) fluid-filled spaces that form around blood vessels in the *pia mater as they penetrate deeper brain tissue. They may dilate, resulting in raised intracranial pressure. [R. Virchow (1821–1902), German pathologist]... virchow–robin spaces
the soft tissue between the bases of the fingers and toes.... web space
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