By O. Akascha. Westminster College, Fulton Missouri.
Their major function seems to be changer discount 20mg apcalis sx amex, and HCO3 is exchanged for luminal Cl via a modification of the electrolyte composition of the pancre- Cl /HCO3 exchanger discount 20mg apcalis sx free shipping. Because the processes involved in the secre- membrane is a protein called cystic fibrosis transmem- tion or uptake of ions are active, centroacinar cells have nu- brane conductance regulator (CFTR). Regulated by ATP, its major function is to which join to form intralobular and then interlobular ducts. The Na /K - major duct, the duct of Wirsung, and a minor duct, the duct ATPase removes cell Na that enters through the Na /H of Santorini. Sodium from the interstitial space follows se- more proximally than the duct of Wirsung, which enters creted HCO3 by diffusing through a paracellular path the duodenum usually together with the common bile duct. Movement of H2O into the duct lumen A ring of smooth muscle, the sphincter of Oddi, surrounds is passive, driven by the osmotic gradient. The sphincter pancreatic HCO3 secretion is the release of H into the of Oddi not only regulates the flow of bile and pancreatic plasma; thus, pancreatic secretion is associated with an acid juice into the duodenum but also prevents the reflux of in- tide in the plasma. Pancreatic Secretions Neutralize Luminal Pancreatic Secretions Are Rich in Acids and Digest Nutrients Bicarbonate Ions As mentioned, one of the primary functions of pancreatic The pancreas secretes about 1 L/day of HCO3 -rich fluid. The enzymes present in intestinal lumen work equal to that of plasma at all secretion rates. The Na and best at a pH close to neutral; therefore, it is crucial to in- K concentrations of pancreatic juice are the same as crease the pH of the chyme. As described above, pancreatic those in plasma, but unlike plasma, pancreatic juice is en- juice is highly basic because of its HCO3 content. Thus, riched with HCO3 and has a relatively low Cl concen- the acidic chyme presented to the duodenum is rapidly tration (Fig. However, because VIP is much weaker than secretin, it produces a weaker pancreatic response when given to- 7. Sim- ilarly, gastrin can stimulate pancreatic enzyme secretion because of its structural similarity to CCK, but unlike CCK, it is a weak agonist for pancreatic enzyme secretion. Seeing, 120 Cl smelling, tasting, chewing, swallowing, or thinking about food results in the secretion of a pancreatic juice rich in en- zymes. In this cephalic phase, stimulation of pancreatic se- 80 cretion is mainly mediated by direct efferent impulses sent by vagal centers in the brain to the pancreas and, to a mi- nor extent, by the indirect effect of parasympathetic stimu- 40 lation of gastrin release. The gastric phase is initiated when HCO Cl 3 food enters the stomach and distends it. Plasma electrolyte composition is provided for pH of the lumen in the duodenum decreases, the secretin comparison. The release of CCK by the I cells (a type The other major function of pancreatic secretion is the of endocrine cell) in the intestinal mucosa is stimulated by production of large amounts of pancreatic enzymes. Some are secreted as proenzymes, which are activated in the duodenal lumen to form the active enzymes. Stimulation of the vagus nerve results predominantly in an increase in en- HCO - HCO - CO2 CO2 + H2O H2CO3 3 3 Carbonic zyme secretion—fluid and HCO3 secretion are margin- anhydrase ally stimulated or unchanged. Sympathetic nerve fibers - - Cl Cl mainly innervate the blood vessels supplying the pancreas, Na+ causing vasoconstriction. Stimulation of the sympathetic nerves neither stimulates nor inhibits pancreatic secretion, probably because of the reduction in blood flow. K+ The secretion of electrolytes and enzymes by the pan- creas is greatly influenced by circulating GI hormones, par- H2O ticularly secretin and cholecystokinin (CCK). Both hor- mones are produced by the small intestine, and the pan- A model for electrolyte secretion by pan- creas has receptors for them. The luminal membrane Structurally similar hormones have effects similar to Cl channel is CFTR (cystic fibrosis transmembrane conduc- those of secretin and CCK. GRP lysine Chymotrypsin(ogen) Cleaves peptides at the carboxyl end of Enzymes hydrophobic amino acids, e. ACh (Pro)elastase Cleaves peptide bonds at the carboxyl 2 Ca terminal of aliphatic amino acids Exopeptidase Ca2 (Pro)carboxypeptidase Cleaves amino acids from the carboxyl CCK stores end of the peptide Amylolytic Ca2 -Amylase Cleaves -1,4-glycosidic linkages of glucose polymers Substance Lipases P Lipase Cleaves the ester bond at the 1 and 3 The stimulation of pancreatic secretion by FIGURE 27. The increase in intracellular Ca re- Carboxylester hydrolase Cleaves cholesteryl ester to free lease and cAMP formation results in an increase in pancre- cholesterol (cholesterol esterase) atic enzyme secretion. The mechanism by which this takes Nucleolytic place is not well understood. Ribonuclease Cleaves ribonucleic acids into mononucleotides Deoxyribonuclease Cleaves deoxyribonucleic acids into mononucleotides BILIARY SECRETION The suffix -ogen or prefix pro- indicates the enzyme is secreted in an in- The human liver secretes 600 to 1,200 mL/day of bile into active form. For example, bile Potentiation, as previously described for gastric secre- salts play an important role in the intestinal absorption of tion, also exists in the pancreas.
If a pregnant woman uses certain teratogenic drugs or is exposed to certain diseases (Rubella virus effective 20 mg apcalis sx, for example) during Diseases of the Abdomen development of the embryo purchase 20 mg apcalis sx overnight delivery, there is a strong likelihood that Any of the abdominal organs may be afflicted by an array of dis- the appendage will be incompletely developed. It is beyond the scope of this text to cover all of these dis- ber of limb deformities occurred between 1957 and 1962 as a eases; instead, an overview of some general conditions will be result of women ingesting the sedative thalidomide during presented. It is estimated Knowledge of the clinical regions of the abdomen (see that 7,000 infants were malformed by this drug. Also important are the locations of the linea Although genetic deformities of the shoulder and upper ex- alba, extending from the xiphoid process to the symphysis pubis, tremity are numerous, only a few are relatively common. Spren- the umbilicus, the inguinal ligament, the bones and processes gel’s deformity affects the development of one or both scapulae. In this condition, the scapula is smaller than normal and is posi- Peritonitis is of major clinical concern. As a result, abduction of the arm is the serous membrane of the abdominal cavity. It lines the abdom- not possible beyond a right angle to the plane of the body. Peritonitis results from any type of contamination of extra digit is incompletely formed and nonfunctional. Syn- the peritoneal cavity,such as from a puncture wound,blood- dactyly, or webbed digits, is likewise a relatively common limb borne diseases,or a ruptured visceral organ. Polydactyly is inherited as a dominant trait, is frequently a complication of infections of the reproductive tract whereas syndactyly is a recessive trait. Peptic ulcers— erosions of the mucous membranes of the stomach or duodenum— are produced by the action of hydrochloric acid (HCl) contained Sprengel’s deformity: from Otto G. Surface and Regional © The McGraw−Hill Anatomy, Sixth Edition Anatomy Companies, 2001 338 Unit 4 Support and Movement Trauma to the Shoulder and Upper Extremity langes. Splinting the finger for a period of time may be curative; however, surgery may be required to avoid a permanent crook in The wide variety of injuries to the shoulder and upper extremity the finger. Diseases of the Shoulder and Upper Extremity It is not uncommon to traumatize the shoulder and upper Inflammations in specific locations of the shoulder or upper ex- extremity of a newborn during a difficult delivery. Upper arm tremity are the only common clinical conditions endemic to birth palsy (Erb–Duchenne palsy) is the most common type of these regions. Bursitis, for example, may specifically afflict any birthing injury, caused by a forcible widening of the angle be- of the numerous bursae of the shoulder, elbow, or wrist joints. Using forceps to rotate the fetus in There are several types of arthritis, but generally they involve utero, or pulling on the head during delivery, may cause this in- synovial joints throughout the body rather than just those in the jury. The site of injury is at the junction of vertebrae C5 and C6 hands and fingers. Carpal tunnel syndrome is caused by compression of the The expression of the injury is paralysis of the abductors and lat- median nerve by the carpal flexor retinaculum that forms the eral rotators of the shoulder and the flexors of the elbow. The nerve compression re- arm will permanently hang at the side in medial rotation. The compression is due to an support of the clavicle and acromion of the scapula superiorly inflammation of the transverse carpal ligament, which may be and the tendons forming the rotator cuff anteriorly. Injuries of this sort are the synovial tendon sheath in the wrist or hand. Sudden jerks of infections are quite common following a puncture wound in the arm are also likely to dislocate the shoulder, especially in which pathogens enter the closed synovial sheath. Many fractures result from extending the arm to of hand function can be prevented by draining the synovial break a fall. The clavicle is the most frequently broken bone in sheath and providing antibiotic treatment. Also common are fractures of the humerus, which are often serious because of injury to the nerves and vessels that par- allel the bone. The surgical neck of the humerus is a common Hip and Lower Extremity fracture site. At this point, the axillary nerve is often damaged, thus limiting abduction of the arm. A fracture in the middle Developmental Conditions third of the humerus may damage the radial nerve, causing paral- The embryonic development of the hip and lower extremity fol- ysis of the extensor muscles of the hand (wristdrop).
The other cord levels listed may have small spinal medullary arteries but not the large diameter 14 apcalis sx 20 mg on-line. Answer E: A pineal tumor impinging on the superior colliculus vessel characteristic of Adamkiewicz apcalis sx 20mg discount. The inferior colliculus is related to the auditory system, trochlear ﬁbers 8. Answer E: The thalamoperforating arteries serve the more ros- innervate the ipsilateral superior oblique muscle, and the posterior tral portions of the dorsal thalamus. These vessels may originate as commissure contains ﬁbers related to the pupillary light pathway. The anterior choroidal artery serves the op- deﬁcits but not speciﬁcally a paralysis of upward gaze. Answer B: Alternating sensory losses accompanied by a motor temporal lobe. The thalamogeniculate artery supplies blood to the deﬁcit on the same side as the loss of vibratory sensation are char- caudal thalamus, the medial striate arteries to the head of the cau- acteristics of the Brown-Séquard syndrome (also commonly called date nucleus, and the lateral striate arteries to much of the lentic- a spinal cord hemisection). Answer A: The claustrum is the thin layer of grey matter that is dromes there are usually characteristic cranial nerve and long tract located between the extreme and external capsules. The external medullary lamina is found at the interface of the lateral 16. Answer E: The rubrospinal tract lies immediately anterior portions of the thalamus with the internal capsule and the lamina (ventral) to, and partially overlaps with, the lateral corticospinal terminalis is the thin structure forming the rostral wall of the third tract. The putamen is located medial to the external capsule spinal cord and is spatially separated from the lateral corticospinal and lateral to the globus pallidus and the stria terminalis is a ﬁber tract. The gracile fasciculus is in the posterior columns, the me- bundle in the groove between the body of the caudate nucleus and dial longitudinal fasciculus is in the ventral funiculus, and the an- the dorsal thalamus. Answer B: Penetrating branches of the posterior spinal artery receives the pathways (medial lemniscus and anterolateral system) serve the posterior columns (gracile and cuneate fasciculi) of the that relay the information lost as a result of the lesion in this spinal cord at all levels. The ventral posteromedial nucleus relays comparable in- serve the gracile nucleus, but this structure is in the medulla, not formation from the face and the medial geniculate nucleus is re- in the spinal cord. The lateral corticospinal tract and the antero- lated to the auditory system. Lesions in the subthalamic nucleus lateral system are served by the arterial vasocorona on the surface result in hemiballismus. The anterolateral system relays pain and of the cord and the internal branches of the anterior spinal artery. Answer D: The putamen and the caudate nucleus originate from position of the anterior spinocerebellar tract; damage to this area the same group of developing neurons, are collectively referred to of the spinal cord would most likely result in a loss of pain and as the neostriatum, and appear in the same shade of grey in a T1- thermal sensations on the contralateral side of the body below the weighted MRI. The lateral corticospinal tract is located internal to the pos- tinctly lighter than the putamen and the dorsomedial nucleus fre- terior spinocerebellar tract, the anterior white commissure and quently appears dark in a shade of grey distinctly different from the anterior corticospinal tract are located in the anterior funicu- that of the globus pallidus. Answer C: The pars caudalis portion of the spinal trigeminal nu- levels. Answer A: Reticulospinal ﬁbers (medial and lateral) and lateral level of the spinal cord. This portion of the spinal trigeminal nu- vestibulospinal ﬁbers are found predominately in the anterolateral cleus is responsible for relaying pain and thermal information orig- area of the spinal cord; medial vestibulospinal ﬁbers are located in inating from the face and oral cavity on one side to the ventral pos- the medial longitudinal fasciculus. In the decerebrate patient, the teromedial nucleus on the contralateral side. The pars interpolaris descending inﬂuence of rubrospinal ﬁbers on spinal ﬂexor motor is found at levels between the obex and the rostral end of the hy- neurons is removed, and descending inﬂuence on extensor motor poglossal nucleus and the pars oralis between the interpolaris and neurons is predominant. The principal sensory nucleus is in area of the cord, and the posterolateral tract do not contain the pons and the mesencephalic nucleus is in the midbrain. The intermediate zone, a 98–106, 120, 130) part of the spinal cord grey matter, contains some of the terminals of these ﬁbers but not the descending tracts in toto. Answer E: The solitary nucleus receives general visceral affer- 95) ent (GVA) and special visceral afferent information (SVA, this in- put is taste) and is located in the region of the medulla served by 20.
Ann Intern Med 120:856-871 Malkasian D 20mg apcalis sx otc, Ross JS (1994) Magnetic resonance imaging of 2 buy apcalis sx 20mg otc. Modic MT, Masaryk TJ, Ross JS, Carter JR (1988) Imaging of the lumbar spine in people without back pain. Boos N, Rieder R, Schade V, Spratt KF, Semmer N, Aebi M (1988) Progressive and regressive changes in the nucleus pul- (1995) Volvo Award in clinical sciences. Radiology 169(1):93-97 racy of magnetic resonance imaging, work perception, and 4. Pearce RH, Thompson JP, Bebault GM, Flak B (1991) psychosocial factors in identifying symptomatic disc hernia- Magnetic resonance imaging reflects the chemical changes of tions. Burns JW, Loecker TH, Fischer JR Jr, Bauer DH (1996) Rheumatol Suppl 27:42-43 Prevalence and significance of spinal disc abnormalities in an 5. Pfirrmann CW, Metzdorf A, Zanetti M, Hodler J, Boos N asymptomatic acceleration subject panel. Aviat Space Environ (2001) Magnetic resonance classification of lumbar interver- Med 67(9):849-853 tebral disc degeneration. Fardon DF, Milette PC (2001) Nomenclature and classification (1990) Abnormal magnetic-resonance scans of the lumbar of lumbar disc pathology. J task Forces of the North American Spine Society, American Bone Joint Surg Am 72(3):403-408 Society of Spine Radiology, and American Society of 22. Savage RA, Whitehouse GH, Roberts N (1997) The relation- Neuroradiology. Spine 26(5):E93-E113 ship between the magnetic resonance imaging appearance of 7. Hauger O, Cotten A, Chateil JF, Borg O, Moinard M, Diard F the lumbar spine and low back pain, age and occupation in (2001) Giant cystic Schmorl’s nodes: imaging findings in six males. Resnick D, Niwayama G (1995) Degenerative disease of the cleus pulposus induces neurophysiologic and histologic spine. In: Resnick D (ed) Diagnosis of bone and joint disor- changes in porcine cauda equina nerve roots. Weishaupt D, Zanetti M, Hodler J, Min K, Fuchs B, Pfirrmann Relationship of Schmorl’s nodes to vertebral body endplate CW, et al (2001) Painful lumbar disk derangement: relevance fractures and acute endplate disk extrusions. Mitra D, Cassar-Pullicino VN, McCall IW (2004) Longitudinal Boos N (2004) MR image-based grading of lumbar nerve root study of vertebral type-1 end-plate changes on MR of the lum- compromise due to disk herniation: reliability study with sur- bar spine. Aprill C, Bogduk N (1992) High-intensity zone: a diagnostic Lumbar disc high-intensity zone. Correlation of magnetic res- sign of painful lumbar disc on magnetic resonance imaging. Modic MT, Steinberg PM, Ross JS, Masaryk TJ, Carter JR study of high intensity zones on MR of lumbar intervertebral (1988) Degenerative disk disease: assessment of changes in discs. Nowicki BH, Yu S, Reinartz J, Pintar F, Yoganandan N, 1):193-199 Haughton VM (1990) Effect of axial loading on neural foram- 13. Weishaupt D, Zanetti M, Boos N, Hodler J (1999) MR imag- ina and nerve roots in the lumbar spine. Radiology 176:433- ing and CT in osteoarthritis of the lumbar facet joints. Pavlov H, Torg JS, Robie B, Jahre C (1987)Cervical spinal Hansson T (1997) Dynamic effects on the lumbar spinal canal: stenosis: determination with vertebral body ratio method. Weishaupt D, Schmid MR, Zanetti M, Boos N, Romanowski KR (1989) Prevalence of lumbosacral intervertebral disk ab- B, Kissling RO et al (2000) Positional MR imaging of the normalities on MR images in pregnant and asymptomatic non- lumbar spine: does it demonstrate nerve root compromise not pregnant women. Kilcoyne2 1 University of Southern California Keck School of Medicine, Los Angeles, CA, USA 2 Department of Radiology, A-030, University of Colorado Health Sciences Center, CO, USA Introduction Infections in bones and joints are usually considered from the point of view of the timing of their presentation – acute, subacute or chronic. Most of the classic terms applied to osteomyelitis refer to chronic osteomyelitis, but the ability to make the diagnosis clinically at an ear- lier stage of disease is important. As we will see, the tibia of a child shows a dis- advanced imaging techniques play a role in early diag- crete radiolucent area in the nosis. Extending su- periorly is a linear lucent tract that has not yet reached the cor- Features of Osteomyelitis tex. This linear tract is typical of Brodie’s abscess Acute Osteomyelitis The initial clinical presentation of acute osteomyelitis latent form of subacute or chronic infection is sclerosing will depend on the history and physical findings. The radiographic signs are usual- Radiography is often negative in the early stages of in- ly nonspecific.
Sensory Organs © The McGraw−Hill Anatomy purchase 20 mg apcalis sx with mastercard, Sixth Edition Coordination Companies buy apcalis sx 20 mg mastercard, 2001 524 Unit 5 Integration and Coordination proprioceptors of tendons, muscles, and joints also provide sen- Eyes Joint, tendon, sory input that is needed to maintain equilibrium (fig. Vestibular apparatus muscle, and The vestibular organs provide the CNS with two kinds of cutaneous receptors receptor information. One kind is provided by receptors within the saccule and utricle, which are sensitive to gravity and to lin- ear acceleration and deceleration of the head, as occur when rid- Cerebellum Vestibular nuclei (brain stem) ing in a car. The other is provided by receptors within the semicircular ducts, which are sensitive to rotational movements, as occur when turning the head, spinning, or tumbling. When the hair cells are displaced in the direc- (control of eye movements) movements) tion of the kinocilium, the cell membrane is depressed and becomes depolarized. When the hair cells are displaced in the opposite direction, the membrane becomes hyperpolarized. Kinocilium Stereocilia Cell membrane (b) At rest (a) (c) Stimulated (d) Inhibited FIGURE 15. Sensory Organs © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 Chapter 15 Sensory Organs 525 Vestibular nerve Macula of the utricle Cochlea (a) Macula Macula of Gelatinous the saccula material Statoconia Stereocilia Gelatinous material Hair cells Hairs of hair cells bend Gravitational force Sensory Supporting nerve fibers cells Creek (b) (c) FIGURE 15. Saccule and Utricle (otolithic) membrane, that supports microscopic crystals of cal- cium carbonate called statoconia (otoliths). The statoconia in- Receptor hair cells of the saccule and utricle are located in a crease the weight of the statoconial membrane, which results in small, thickened area of the walls of these organs called the mac- a higher inertia (resistance to change in movement). Cytoplasmic extensions of the hair When a person is upright,the hairs of the utricle project cells project into a gelatinous mass, called the statoconial vertically into the statoconial membrane,whereas those of the saccule project horizontally. During forward acceleration,the sta- toconial membrane lags behind the hair cells,so the hair cells of macula: L. Sensory Organs © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 526 Unit 5 Integration and Coordination Vestibular nerve Ampullae Cochlea (a) Cupula Hair bundle Crista ampullaris Hair cells Supporting cells Sensory nerve fibers Creek (b) (c) FIGURE 15. Like the sac- ertia of the statoconial membrane similarly causes the hair cells cule and utricle, the hair cells have cytoplasmic extensions that of the saccule to be pushed upward when a person jumps from a project into a dome-shaped gelatinous mass called the cupula (ky- raised platform. When the hair cells within the cupula are bent by processes,the utricle is more sensitive to horizontal acceleration, rapid displacement of the fluid within the semicircular ducts, as in and the saccule is more sensitive to vertical acceleration. The spinning around, sensory impulses travel to the brain by way of changed pattern of action potentials in sensory nerve fibers that the vestibular nerve. Neural Pathways Sensory impulses from the vestibular organs are conveyed Stimulation of the hair cells in the vestibular apparatus activates to the brain by way of the vestibular nerve, a component of the the sensory neurons of the vestibular nerve. The Semicircular Canals vestibular nuclei, in turn, send fibers to the oculomotor center of Receptors of the semicircular canals are contained within the am- pulla at the base of each semicircular duct. Sensory Organs © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 Chapter 15 Sensory Organs 527 the brain stem and to the spinal cord. Neurons in the oculomo- on the diagnosis of sensory disorders and on developmental prob- tor center control eye movements, and neurons in the spinal lems that can affect the eyes and ears. In addition, the more cord stimulate movements of the head, neck, and limbs. Diagnosis of Eye and Ear Disorders The dizziness and nausea that some people experience when they spin rapidly is explained by the activity occurring within the vestibular organs. When a person first begins to spin, the Eye inertia of the endolymph within the semicircular ducts causes the cupula to bend in the opposite direction. As the spin continues, There are two distinct professional specialties concerned with however, the endolymph and the cupula will eventually be moving the structure and function of the eye. If movement is sud- ical profession concerned with assessing vision and treating vi- denly stopped, the greater inertia of the endolymph causes it to continue moving in the direction of spin and to bend the cupula in sual problems. The eyes slowly drift in the cine concerned with diagnosing and treating eye diseases. The following devices are fre- ing this effect may feel that they are spinning, or that the room is. If the vertigo is the eyes to dilate the pupils and temporarily inactivate the ciliary sufficiently severe, or if the person is particularly susceptible, the autonomic nervous system may become involved. This can pro- muscles; (2) a Snellen’s chart, which is used to determine the vi- duce dizziness, pallor, sweating, and nausea. List the structures of the outer ear, middle ear, and measure ocular tension, important in detecting glaucoma. Explain how movements of the basilar membrane can code conditions of the ear, nose, and throat.