By E. Kulak. Eastern Kentucky University. 2018.
The correct sequence for removal of material from the blood through the nephron is a cheap rizatriptan 10mg. Afferent arteriole → Glomerulus → Proximal convoluted tubule → Loop of Henle → Distal convoluted tubule → Collecting tubule b rizatriptan 10mg with mastercard. Afferent arteriole → Glomerulus → Distal convoluted tubule → Loop of Henle → Proximal convoluted tubule → Collecting tubule c order 10mg rizatriptan visa. Afferent arteriole → Collecting tubule → Glomerulus → Proximal convoluted tubule → Loop of Henle → Distal convoluted tubule d. Efferent arteriole → Proximal convoluted tubule → Glomerulus → Loop of Henle → Distal convoluted tubule → Collecting tubule 11. Distal convoluted tubules Chapter 12: Filtering Out the Junk: The Urinary System 199 Getting Rid of the Waste After your kidneys filter out the junk, it’s time to deliver it to the bladder. Surfing the ureters Ureters are narrow, muscular tubes through which the collected waste travels. About 10 inches long, each ureter descends from a kidney to the posterior lower third of the bladder. Like the kidneys themselves, the ureters are behind the peritoneum outside the abdominal cavity, so the term retroperitoneal applies to them, too. It also has a middle layer of smooth muscle tissue that propels the urine by peristalsis — the same process that moves food through the digestive system. So rather than trickling into the bladder, urine arrives in small spurts as the muscular contractions force it down. The tube is surrounded by an outer fibrous layer of connective tissue that supports it during peristalsis. Ballooning the bladder The urinary bladder is a large muscular bag that lies in the pelvis behind the pubis bones. There are three openings in the bladder: two on the back side where the ureters enter and one on the front for the urethra, the tube that carries urine outside the body. The neck of the bladder surrounds the urethral attachment, and the internal sphincter (smooth muscle that pro- vides involuntary control) encircles the junction between the urethra and the bladder. When full, the bladder’s lining is smooth and stretched; when empty, the lining lies in a series of folds called rugae (just as the stomach does). When the bladder fills, the increased pressure stimulates the organ’s stretch receptors, prompting the individual to urinate. The male and female urethras Both males and females have a urethra, the tube that carries urine from the bladder to a body opening, or orifice. Both males and females have an internal sphincter con- trolled by the autonomic nervous system and composed of smooth muscle to guard the exit from the bladder. Both males and females also have an external sphincter com- posed of circular striated muscle that’s under voluntary control. The female urethra is about one and a half inches long and lies close to the vagina’s anterior (front) wall. The external sphinc- ter for the female urethra lies just inside the urethra’s exit point. Several openings appear in this region of the urethra, including a small opening where sperm from the vas deferens and ejacu- latory duct enters, and prostatic ducts where fluid from the prostate enters. The membranous urethra is a small 1- or 2-centimeter portion that contains the external sphincter and penetrates the pelvic floor. The cavernous urethra, also known as the spongy urethra, runs the length of the penis on its ventral surface through the corpus spongiosum, ending at a vertical slit at the end of the penis. The and urinary systems is complete in male urethra runs through the the human same “plumbing” as the male reproductive system. The internal sphincter found at the junction of the bladder neck and the urethra is composed of a. Smooth muscle tissue Spelling Relief: Urination Urination, known by the medical term micturition, occurs when the bladder is emptied through the urethra. Although urine is created continuously, it’s stored in the bladder until the individual finds a convenient time to release it. Mucus produced in the blad- der’s lining protects its walls from any acidic or alkaline effects of the stored urine. When there is about 200 milliliters of urine distending the bladder walls, stretch recep- tors transmit impulses to warn that the bladder is filling. Afferent impulses are trans- mitted to the spinal cord, and efferent impulses return to the bladder, forming a reflex arc that causes the internal sphincter to relax and the muscular layer of the bladder to contract, forcing urine into the urethra. The afferent impulses continue up the spinal cord to the brain, creating the urge to urinate. Because the external sphincter is com- posed of skeletal muscle tissue, no urine usually is released until the individual volun- tarily opens the sphincter. Renal artery Chapter 12: Filtering Out the Junk: The Urinary System 203 Answers to Questions on the Urinary System The following are answers to the practice questions presented in this chapter. Irregular sac-like structures for collecting urine in the renal pelvis e Collecting tubule: d. The other answer option can’t be correct because carbon dioxide exits the body through the lungs.
The participants were then followed up after one year and the occurrence of a pain episode and their physical functioning was assessed generic rizatriptan 10 mg with mastercard. The results showed that 19 per cent of the sample reported an episode of back pain at follow-up and that those with higher baseline scores of fear avoidance were twice as likely to report back pain and had a 1 purchase rizatriptan 10mg without prescription. Some research also suggests that fear may also be involved in exacerbating existing pain and turning acute pain into chronic pain purchase rizatriptan 10mg with visa. They argued that pain functions by demanding attention which results in a lowered ability to focus on other activities. Their results indicated that pain related fear increased this attentional interference suggesting that fear about pain increased the amount of attention demanded by the pain. They con- cluded that pain related fear can create a hyper-vigilance towards pain which could contribute to the progression from acute to chronic pain. These conclusions were further supported by a comprehensive review of the recent research. This indicates that treat- ment which exposes patients to the very situations that they are afraid of, such as going out and being in crowds, can reduce fear avoidance beliefs and modify their pain experience (Vlaeyen and Linton 2000). The role of cognition Catastrophizing Patients with pain, particularly chronic pain, in line with many other patients often show catastrophizing. Catastrophizing has been linked to both the onset of pain and the development of longer-term pain problems (Sullivan et al. The results showed some small associ- ations between this and the onset of back pain by follow-up. Their new measure consisted of three subscales reﬂecting the dimensions of catastro- phizing, namely rumination, magniﬁcation and helplessness. They then used this meas- ure to explore the relationship between catastrophizing and pain intensity in a clinical sample of 43 boys and girls aged between 8 and 16. The results indicated that catastro- phizing independently predicted both pain intensity and disability regardless of age and gender. The authors argued that catastrophizing functions by facilitating the escape from pain and by communicating distress to others. Meaning Although at ﬁrst glance any pain would seem to be only negative in its meaning, research indicates that pain can have a range of meanings to diﬀerent people. For example, the pain experienced during childbirth although painful, has a very clear cause and consequence. If the same kind of pain were to happen outside of childbirth then it would have a totally diﬀerent meaning and would probably be experienced in a very diﬀerent way. Beecher (1956), in his study of soldiers’ and civilians’ requests for medication, was one of the ﬁrst people to examine this and asked the question: ‘What does pain mean to the individual? This has also been described in terms of secondary gains whereby the pain may have a positive reward for the individual. Self-efﬁcacy Some research has emphasized the role of self-eﬃcacy in pain perception and reduction. In addition, the concept of pain locus of control has been developed to emphasize the role of individual cognitions in pain perception (Manning and Wright 1983; Dolce 1987; Litt 1988). For example, in the experimental study described above, James and Hardardottir (2002) illustrated this association using the cold pressor task. Eccleston and Crombez have carried out much work in this area which they review in 1999. They illustrate that patients who attend to their pain experience more pain than those who are distracted. This association explains why patients suﬀering from back pain who take to their beds and therefore focus on their pain take longer to recover than those who carry on working and engaging with their lives. This association is also reﬂected in relatively recent changes in the general management approach to back pain problems – bedrest is no longer the main treatment option. In addition, Eccleston and Crombez provide a model of how pain and attention are related (Eccleston 1994; Eccleston and Crombez 1999). They argue that pain interrupts and demands attention and that this interrup- tion depends upon pain-related characteristics such as the threat value of the pain and environmental demands such as emotional arousal. They argue that pain causes a shift in attention towards the pain as a way to encourage escape and action. The result of this shift in attention towards the pain is a reduced ability to focus on other tasks resulting in attentional interference and disruption. This disruption has been shown in a series of experimental studies indicating that patients with high pain perform less well on diﬃcult tasks which involve the greatest demand of their limited resources (e. Behavioural processes Pain behaviour and secondary gains The way in which an individual responds to the pain can itself increase or decrease the pain perception. In particular, research has looked at pain behaviours which have been deﬁned by Turk et al. It has been suggested that pain behaviours are reinforced through attention, the acknowledgment they receive and through secondary gains, such as not having to go to work.
Peristalsis continues into the small intestine 10 mg rizatriptan for sale, shortening and lengthening the villi to mix intestinal juices with food and increase absorption 10mg rizatriptan mastercard. Intestinal glands lie in the depressions between villi discount rizatriptan 10mg overnight delivery, and packed inside these glands are antimicrobial Paneth cells within glands called the crypts of Lieberkühn, which secrete enzymes that assist pancreatic enzymes. Intestinal juices contain three types of enzymes: Enterokinase has no enzyme action by itself, but when added to pancreatic juices, it combines with trypsinogen to form trypsin, which can break down proteins. Erepsins, or proteolytic enzymes, don’t directly digest proteins but instead complete protein digestion started elsewhere. Inverting enzymes split disaccharides into monosaccharides as follows: Enzyme Disaccharide Monosaccharides Maltase Maltose Glucose + Glucose Lactase Lactose Glucose + Galactose Sucrase Sucrose Glucose + Fructose Liver The largest gland in the body, the liver is divided into a large right lobe and a small left lobe by the falciform ligament, another peritoneal fold. Two smaller lobes — the quadrate and caudate lobes — are found on the lower (inferior) and back (posterior) sides of the right lobe. The quadrate lobe surrounds and cushions the gallbladder, a pear-shaped structure that stores and concentrates bile, which it empties periodically through the cystic duct to the common bile duct and on into the duodenum during digestion. Bile aids in the digestion and absorption of fats; it consists of bile pigments, bile salts, and cholesterol. The liver secretes diluted bile through the hepatic ducts into the cystic duct and on into the gallbladder. Blood from the interlobular veins and arter- ies circulates through the sinusoids with food and oxygen for the liver cells, picking up materials along the way. The blood then enters the intralobular veins, which carry it to the sublobular veins, which empty into the hepatic vein, which leads to the inferior vena cava. Bile secreted from the liver cells is carried by biliary canaliculi (bile capil- laries) to the bile ducts and then to the hepatic ducts. Considering the number of vital roles the liver plays, the complexity of that process isn’t too surprising. Among the liver’s various functions are Production of blood plasma proteins including albumin, antibodies to fend off disease, a blood anticoagulant called heparin that prevents clotting, and bile pig- ments from red blood cells, the yellow pigment bilirubin, and the green bile pig- ment biliverdin Storage of vitamins and minerals as well as glucose in the form of glycogen Conversion and utilization through enzyme activity of fats, carbohydrates, and proteins Filtering and removal of nonfunctioning red blood cells, toxins (isolated by Kupffer cells in the liver) and waste products from amino acid breakdown, such as urea and ammonia Unfortunately, a number of serious diseases can damage the liver. The hepatitis virus inflames the gland, and cirrhosis caused by repeated toxic injury (often through alco- hol or other substance abuse) destroys Kupffer cells and replaces them with scar tissue. Also, painful gallstones can develop when cholesterol clumps together to form a center around which the gallstone can form. The head is attached to the body of the gland by a slight constriction called the neck, and the opposite end gradually tapers to form a tail. The pancreatic duct extends from the head to the tail, receiving the ducts of various lobules that make up the gland. It generally joins the common bile duct, but some 40 percent of humans have a pancreatic duct and a common bile duct that open separately into the duodenum. Uniquely, the pancreas is both an exocrine gland, meaning that it releases its secretion externally either directly or through a duct, and an endocrine gland, meaning that it produces hormonal secretions that pass directly into the bloodstream without using a duct. However, most of the pancreas is devoted to being an exocrine gland secreting pancreatic juices into the duodenum. The endocrine portion of the gland secretes insulin vital to the control of sugar metabolism in the body through small, scattered clumps of cells known as islets of Langerhans. Because it contains sodium bicarbonate, pancreatic juice is alkaline, or base, with a pH of 8. Enzymes released by the pancreas act upon all types of foods, making its secretions the most important to digestion. Its enzymes include pancreatic amylase, or carbohydrate enzymes; pancreatic lipase, or fat enzymes; trypsin, or protein enzymes; and nuclease, or nucleic acid enzymes. The most commonly known pancreatic disease is called diabetes mellitus, or sugar diabetes, which occurs when the islets of Langerhans cease producing insulin. Without insulin, the body can’t use sugar, which builds up in the blood and is excreted by the kidneys. Chapter 9: Fueling the Functions: The Digestive System 157 Large intestine After chyme works its way through the small intestine, it then must move through 5 feet or so of large intestine. The byproduct of the small intestine’s work enters at the ileocaecal valve and then moves through the following regions of the large intestine: Cecum → Vermiform appendix → Ascending colon→ Transverse colon → Descending colon → Sigmoid colon → Rectum → Anus The large intestine is about 3 inches wide at the start and decreases in width all the way to the anus. As the unabsorbed material moves through the large intestine, excess water is reabsorbed, drying out the material. In fact, most of the body’s water absorp- tion takes place in the large intestine. Peristaltic movement continues, albeit rather feebly, in the cecum and ascending colon. The large intestine has a longitudinal muscle layer in the form of three bands running from the cecum to the rectum called the taenia coli.
Noninvasive approaches The value of invasive haemodynamic monitoring (especially pulmonary artery catheters) remains controversial discount rizatriptan 10 mg amex, but noninvasive alternatives for measuring cardiac output are increasingly reliable cheap 10mg rizatriptan fast delivery, often providing real-time information (enabling earlier intervention) (Asensio et al generic rizatriptan 10mg online. Correlation with thermodilution measurements and clinical reliability are debated: Haller et al. Readings can be unreliable with: ■ dysrhythmias (especially bundle branch blocks and tachycardias above 150) ■ myocardial infarction ■ metal (e. Single measurements can take half an hour, and are affected by: ■ anaemia ■ breast tissue ■ emphysema Ideally all measurements should be performed by a single experienced operator, but this is often impractical. Problems include ■ discomfort (thus only suitable for sedated and ventilated patients (Hinds & Watson 1996)); ■ potential oesophageal trauma (Valtier et al. Transtracheal probes at the distal end of endotracheal tubes can provide similar measurements with easier access, although preliminary reports often (40 per cent) show poor quality signals (Tibby et al. Implications for practice ■ haemodynamic monitoring can provide useful diagnostic information, but is not inherently therapeutic; decisions to use equipment should evaluate benefits against risks ■ information may enhance patient care, but nursing should focus on the person rather than the machine ■ needs to prioritise time may preclude taking observations in favour of more urgent tasks ■ any equipment may introduce infection; more invasive equipment increases infection risk, so use should be aseptic ■ noninvasive modes are preferable if they are available and reliable ■ trends are more significant than absolute figures Intensive care nursing 190 ■ nurses should minimise discomfort from equipment wherever possible, providing prescribed analgesia and sedation where necessary and explaining equipment and procedures to allay anxiety ■ no observation should be ‘routine’; nurses should only perform observations if information may be used, and should consider carefully before delegating tasks to anyone unable to interpret information Summary Heamodynamic monitoring necessarily forms a major aspect of intensive care nursing; this chapter has described most methods currently used, with main complications. All modes, especially invasive ones, have complications and so should only be used as long as benefits outweigh problems. Nurses should actively assess and, where possible, initiate appropriate monitoring, and remember their individual accountability when using equipment (e. Information gained should be actively used for patient treatment, and so where necessary should be reported and recorded. Further reading Most textbooks include an overview of haemodynamic monitoring; Coombs’s (1993) article offers useful nursing perspectives. Draper (1987) provides a thorough review of arterial cuff pressure measurement, while Campbell (1997) gives useful descriptions of arterial pressure waveform monitoring. Shoemaker’s interest in invasive cardiac monitoring has been increasingly replaced by noninvasive modes (see Shoemaker et al. From these numerical values, what results would you expect for Mrs Goodwin’s peripheral perfusion and respiratory status (e. Formulate a care plan which includes rationale for choice of prescribed drug therapies aimed at reducing afterload, preload and myocardial oxygen consumption, increasing cardiac output and peripheral perfusion, whilst preventing further ischaemia. Frequently encountered dysrhythmias are also described following the normal conduction pathway. The etymologically more accurate term ‘dysrhythmia’ is used rather than the common term ‘arrhythmia’, since, except for asystole, rhythms are problematic rather than absent. Cardiac rhythm affects blood pressure: blood pressure=heart rate×stroke volume×systemic vascular resistance Atrioventricular dyssychrony (almost all dysrhythmias) causes loss of ‘atrial kick’, reducing stroke volume by one-fifth (Cohn & Gilroy-Doohan 1996). Some specific drugs and treatments are identified with each dysrhythmia discussed; other drugs may be seen in practice, and users should consult data sheets or pharmacopaedias for detailed information on drugs. Common problems and approaches include: conduction: ■ bradycardic dysrhythmias may need chronotropes (e. Ventricular conduction may be blocked with: • β-blockers (esmolol, sotalol, propanolol), which inhibit beta receptors (see Chapter 34) • calcium antagonists (amiodarone, verapamil) which increase refractory periods of action potentials may be used to slow ventricular conduction. Monitors are neither an end in themselves, nor a substitute for observing patients, but rather a means to providing information which should be evaluated in context of the whole person. Action potential Ion exchange between intracellular and extracellular fluid creates transmembrane imbalances, enabling muscular (electrical) activity, hence action potential (Figure 21. When electrical activity is absent, resting sinoatrial potential is about −90 millivolts (mv). The three main ions involved with action potential are ■ sodium ■ potassium ■ calcium Extracellular concentrations of about 140 mmol/litre of sodium and 4. Action potential changes along conduction pathways to ‘overpacing’ lower pacemakers. This lasts only milliseconds before resting charge of −90 mv (repolarisation) is restored. Action potential of pacemaker cells (sinoatrial node, atrioventricular node and conducting fibres) differs from other myocytes, reflecting the automaticity of pacemaker cells. This prevents cardiac muscle responding to further stimulus, thus ensuring coordinated contraction. Plateau time influences contractile strength of muscle fibres (which determines stroke volume). Hypercalcaemia increases contractility; calcium antagonists can reduce excitability. Catecholamines increase depolarisation (increase duration of phase 4) in pacemaker cells, hence causing tachycardia. Vagal stimulation (mediated through acetylcholine) slows depolarisation (decreases slope in phase 4) of pacemaker cells, causing bradycardia.