Hydrozoa is a class of animals of the sub-kingdom Coelenterata, in which the walls of the body inclose a simple undivided cavity which acts both as a body cavity and a digestive cavity. The body is essentially composed of two layers, an outer layer or ectoderm and an inner or entoderm. Reproductive organs are developed as external processes of the body-wall, but reproduction also takes place by fission.
The Hydrozoa are all aquatic and almost all marine. The fresh-water hydra is a very good type of the class. The body is quite soft, and when fully contracted appears like a particle of matter resting on the surface of a plant or stone; but when expanded it shows a long slender body of a bright green or light-brown colour. One end of the body develops into a number of long slender tentacles, within which, near their bases, the mouth of the animal is found. This is the distal or free-growing end.
The other and more slowly growing end is known as the proximal, and ends in a kind of disc or foot by which the hydra attaches itself to objects. The body is hollow from one end to the other. It is mainly found in semi-stagnant waters, where, hanging from its foot-disc, with its long tentacles expanded, it seizes on the small crustaceans or other suitable prey which comes in contact with it. Its tentacles have a stinging power which soon paralyses its prey. Under favourable conditions one or more hydras are usually found attached to the parent form. Such are produced by a process of budding from the parent. Each of these ultimately separates from the parent stem and becomes an independent hydra.
The Hydrozoa were divided by Professor Nicholson into six sub-classes: the Hydroida, the Siphonophora, the Lucernarida, the Graptolitoidea, the Hydrocorallinse, and the Stromatoporoidea. Research Hydrozoa
Scarabaeidae is the chafers and dung beetles family of insects of the order Coleoptera. The members have the three distal segments of the antennae widened on one side to form a characteristic lamellate club. The larvae - known as grubs - develop in soil where they live on roots or are found in dung and other decaying organic matter. Research Scarabaeidae
The autonomic nervous system is responsible for the self-controlling aspects of the body's nervous network, and is under the control of the cerebral cortex, the hypothalmus, and the medulla oblongata. Working in tandem with the central nervous system, the autonomic nervous system features two subsystems which regulate body functions such as involuntary smooth muscle movement and heart rate. These two subsystems are called the sympathetic and parasympathetic nervous system, and their functions operate in opposition to one another, delicately balancing the bodily functions which they control. The sympathetic nervous causes fight or flight responses in moments of stress or stimulus, such as increased heart rate, saliva flow, and perspiration. The parasympathetic system counterbalances these effects by slowing the heart rate, dilating blood vessels, and relaxing involuntary smooth muscle fibres. Viewed individually, the sympathetic nervous system, also referred to as the thoracolumbar system, features a series of nerves which branch out of the spinal cord between the first thoracic vertebra and the second lumbar vertebra. These nerve fibres join into a long trunk of fibres, called the sympathetic trunk, on each side of the spinal cord. Along the sympathetic trunk are enlarged clusters of nerve fibres, called ganglia.
From these ganglia, a number of nerve fibres extend throughout the body's tissues. Many of these nerves create additional ganglia, such as the celiac ganglia and the mesenteric ganglia. The sympathetic nerves are responsible for contracting involuntary smooth muscle fibres, viscera, and blood vessels, speeding up the heart rate, and dilating the bronchial tubes in moments of stress. The parasympathetic nervous system, also referred to as the craniosacral system, features ganglia in the midbrain, in the medulla oblongata, and in the sacral region. The first two, the cranial ganglia of the parasympathetic system, give pass impulses to the facial, oculomotor, glossopharyngeal, and vagus nerves. The sacral group of parasympathetic nerves originate at the second, third, and fourth vertebrae and extend nerves to the bladder, the distalcolon, the rectum, and the genitals. The nerves of the parasympathetic nervous system are responsible for conserving and restoring energy in the body following a sympathetic response to stress. Research Autonomic Nervous System
Each foot is made up of twenty-six bones which form the ankle, top and bottom of the foot, and toes. These bones are articularly specialized, allowing a wide range of flexibility, while being able to withstand the incredible amounts of stress placed upon them. It is estimated that each stride of an adult places 900 pounds per square inch on the bottom of the foot. Seven of these bones form the compact arrangement of the ankle, or tarsus, and the heel. These tarsal bones include the navicular, the three cuneiform, the cuboid, the talus, and the calcaneus bones.
These tarsal bones are arranged generally in two rows, the proximal and distal. The distal tarsals articulate with the five metatarsals. The long metatarsals form the broad, long structure of the foot, as seen in the superior view. These, in turn, articulate with the proximal phalanges. The proximal phalanges join with the middle phalanges, which articulate with the end sections of the toes, called distalphalanges. The large toe is the exception, as it lacks a middle phalanx. Ligaments connect the bones of the foot together and allow the muscles of the calf to remotely influence these bones. Research Bones of the Foot
The brachioradialis (supinator longus) originates two-thirds of the way down the humerus between the triceps and the brachialis. The muscle begins wide and flat and twists toward the front of the arm as it descends. It then widens and flattens again before ending in a flat tendon, which inserts on the thumb side of the radius. It is innervated by branches of the radial nerve and supplied by radial recurrent artery. Unlike most of the long tendons of the forearm, the tendon does not cross the wrist joint, but rather ends at the distal end of the radius. This muscle bends the forearm at the elbow. It does not assist in turning the forearm. Research Brachioradialis
The collecting tubules of the kidney are responsible for collecting the urine from the distal convoluted tubule of the nephron and passing it to the calyces, and from there into the renal pelvis reservoir. The collecting tubules are relatively straight, distinguishing them from the proximal and distal convoluted tubules. Research Collecting Tubule
Colostomy is the operation of opening into the colon, or lower portion of the intestine. This procedure is one of the most important in abdominal surgery. It is sometimes necessary as a life- saving measure. It may be temporary or permanent as an artificial anus in the radical treatment of rectal cancer. Because of its appearance, its inconvenience and the very thought of an artificial opening in the abdominal wall a great deal of care is necessary to allay the anxieties of patients and their relatives when colostomy is necessary.
In some cases of acute intestinal obstruction the surgeon explores the abdomen and finds perhaps a large mass in the region of the pelvic colon or rectum that cannot be removed. An emergency colostomy is then performed in the transverse colon with the immediate purpose of saving life and with the further objective of providing temporary drainage should the growth be removable at a later date. In some such cases, when at first sight the primary cause of the obstruction seems beyond any possibility of surgical removal, after several weeks of colostomy drainage the infection subsides and the affected portion of bowel may then be removed. Colostomy may be necessary as a preliminary to other operations involving removal of the large bowel. Such an occasion arises if diverticulitis has produced vesico-colic fistula (between the colon and bladder). In some cases of severe incontinence due to abnormality or injury to the anus, a left iliac colostomy enables the patient to be free of the terrible inconvenience of perpetual soiling in the perineum. Injuries or abnormalities of the spinal cord produce paralysis of the anal sphincter mechanism and sometimes colostomy is essential. Congenital absence of the rectum or anus requires an emergency colostomy within a day or so of birth.
There are two main forms of colostomy. First is the loop colostomy which has two limbs. The opening is at the apex of the loop and the bowel has not been divided completely across. A variation of the loop colostomy is the double- barrel form in which the two limbs of the loop are separated by a piece of skinrafter complete division. This is also described as a defunctioning colostomy as it prevents the spill of faeces from the proximal to the distalloop. A second variety is the spur colostomy where a spur is formed by suturing the two ends together for several centimeters inside the abdomen. This is of particular value if the colostomy is temporary as the spur can be destroyed by a crushing clamp without risk of peritonitis or perforation since the limbs have become sealed together. When the spur breaks down, the artificial opening on the surface shrinks and sinks back below the skin level. The aim is that this should close spontaneously without further operation. The third type is the terminal colostomy in which the distal portion of bowel is removed completely or in the case of excision of rectum the lower end is closed to form a blind end. In grave emergencies the simplest form of colostomy is performed in which a loop of colon is brought out through the abdominal wall, where it is held by the insertion of a glassrod passed through a small hole in the mesentery. The ends of the glassrod are connected by a loop of rubber tubing which forms a 'bucket handle' . The abdominal wall is closed around the protrusion of the colostomy. Exteriorisation is another way of performing a colostomy. If a growth is present in a part of the bowel which can be brought readily through the abdominal wall (e.g. transverse or pelvic colon) the affected loop containing the growth is left outside and the peritoneum, muscles and skin are closed around the base of the loop where the two limbs converge. The loop of colon containing the growth is then removed, leaving two open ends of el which can later be joined by crushing the spur between them. This operation avoids the handling of growth or unprepared bowel while the peritoneal cavity is open and so diminishes the risk of peritonitis. A formal operation for closure is required if a spur has not been made.
At the end of the operation a small incision is usually made in the apex of the loop to allow the immediate discharge of gas and faecal material which is collected as cleanly as possible before the patient leaves the theatre. A dressing of petroleum jelly gauze or tullegras is applied on the exposed bowel. The skin incision may be sealed with Whitehead's varnish and a pad of cellulosetissue and wool is bandaged lightly over the opening. For fear of contaminating the abdominal wound before the peritoneal cavity has become sealed, the former practice was to leave the colostomy unopened for 48 hours. The initial opening may be enlarged by the surgeon two or three days after the colostomy has been raised. The bowel is usually divided (without anaesthetic) by an electric cautery which seals the blood vessels and prevents bleeding from the very vascular mucousmembrane and muscle wall of the bowel. A method of draining the colostomy is by the use of Paul's tube. This is an angled wide glass tube which is inserted through a hole in the colostomy loop. It is tied in position in the same way as the caecostomy catheter and connected to a bedside jar with wide, thin, latex tubing. Research Colostomy
The convoluted tubules of the kidney are responsible for collecting waste liquid after it passes through the opening in the Bowman's capsule, and passing it through the loop of Heinle and into the distal convoluted tubule. Research Convoluted Tubule
Abbreviations
Research Hydrozoa
