By E. Pyran. California State University, Los Angeles.
Sensory Organs © The McGraw−Hill Anatomy buy 180 mg allegra mastercard, Sixth Edition Coordination Companies buy 180 mg allegra amex, 2001 Chapter 15 Sensory Organs 507 Ciliary muscle fibers relaxed Suspensory ligament taut Lens thin and focused for distant vision (a) Ciliary muscle fibers contracted Suspensory ligament relaxed Lens thick and focused for close vision (b) FIGURE 15 generic 180 mg allegra visa. There are no The central artery (central retinal artery) branches from photoreceptors in the area where the optic nerve is attached to the ophthalmic artery and enters the eyeball in contact with the the eyeball. A person is normally unaware of the divides into superior and inferior branches, each of which then blind spot because (1) the eyes continually move about, (2) an divides into temporal and nasal branches to serve the inner lay- object is viewed from a different angle with each eye, and (3) the ers of the retina (see fig. The central vein drains blood image of an object that falls on the blind spot of one retina will from the eyeball through the optic disc. The blind spot can easily be tral artery can be observed within the eyeball through an oph- demonstrated as described in figure 15. An examination of the internal eyeball with an ophthalmoscope Blood Supply to the Eyeball is frequently part of a routine physical examination. If they appear abnormal (for example, Both the choroid and the retina are richly supplied with blood. Diseases such as arterioscle- eyeball and traverse the choroid to the ciliary body and base of the rosis, diabetes, cataracts, or glaucoma can be detected by examin- iris. Although the ciliary arteries enter the eyeball independently, ing the internal eyeball. Sensory Organs © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 508 Unit 5 Integration and Coordination TABLE 15. The scleral venous sinus is located at the junction of the cornea and iris. The interior of the eyeball is separated by the lens and its associ- The large posterior cavity is filled with a transparent jelly- ated lens capsule into an anterior cavity and a posterior cavity like vitreous humor. The anterior cavity is subdivided by the iris into ular pressure that maintains the shape of the eyeball and holds an anterior chamber and a posterior chamber (see fig. Unlike aqueous humor, vitreous The anterior chamber is located between the cornea and the iris. Additional vitreous humor forms as a person’s eyes become pensory ligament and lens. Aqueous humor also Puncture wounds to the eyeball are especially dangerous and provides nutrients and oxygen to the avascular lens and cornea. Protective equipment such as goggles, shields, and shatterproof lenses should be used in haz- An estimated 5. If the eye is punctured, the the vascular epithelium of the ciliary body (fig. From its main thing to remember is to leave the object in place if it is still im- site of secretion within the posterior chamber, the aqueous paling the eyeball. Removal may allow the fluids to drain from the humor passes through the pupil into the anterior chamber. From eyeball, causing loss of intraocular pressure, a detached retina, and possibly blindness.
Oral contraceptives are breath sounds in both lung fields allegra 120mg with amex, with expiratory wheez- her only medication buy allegra 180 mg low cost. A pulse intravenous drugs and has no other risk factors for HIV oximetry reading reveals his blood hemoglobin oxygen disease cheap 180 mg allegra overnight delivery. Her family history is negative for asthma and saturation is 91% when breathing room air. Pulmonary function tests reveal severe limitation of Physical examination reveals a mildly obese woman airflow rates, particularly expiratory airflow. Her blood Questions pressure is 140/80 mm Hg, and no jugular vein disten- 1. What are the common spirometry findings associated with sion is observed. What are the mechanisms of airflow limitation in emphy- and her temperature is 38 C. What is the most commonly held theory explaining the de- gases, obtained while she was breathing room air, reveal velopment of emphysema? Her alveolar-arterial (A-a)O2 gradient is Answers to Case Study Questions for Chapter 19 40 mm Hg. The hallmark of emphysema is the limitation of airflow out normal flora. In emphysema, expiratory flow rates (FVC, shadow and clear lung fields, except for a small periph- FEV1, and FEV1/FVC ratio) are significantly decreased. A lung scan reveals ever, some lung volumes (TLC, FRC, and RV) are increased, an embolus in the left lower lobe. What is the cause of a widened alveolar-arterial gradient in include hypersensitivity of airway smooth muscle, mucus patients with pulmonary embolism? What causes the decreased arterial PCO2 and elevated arte- creased dynamic airway compression as a result of in- rial pH? Many of the pathophysiological changes in emphysema are Answers to Case Study Questions for Chapter 20 a result of the loss of lung elastic recoil and destruction of 1. This is thought to be a re- embolus will cause blood flow to be shunted to another re- sult of an imbalance between the proteases and antipro- gion of the lung. Because cardiac output is unchanged, the teases ( 1-antitrypsin) in the lower respiratory tree. Nor- shunting of blood causes overperfusion, which causes an mally, proteolytic enzyme activity is inactivated by abnormally low A/ ratio in another region of the lungs. DLCO decreases with anemia because there is less hemoglo- poxemia (a low arterial PO2).
I was once testifying in a fatal house fire case and pointed out the hot “zigger wire” spring scars in a projected photograph of the patient’s thigh buy discount allegra 180 mg on line, a pattern pro- viding proof that the patient had been burned in that same chair from which he was removed cheap allegra 120mg otc. The plaintiff’s attorney showed his irritation and replied order 180mg allegra mastercard, “I suppose that you are going to tell me that you are an expert on furniture, as well. Without my having returned an angry comment to his opener, he dropped that line of questioning with a look of disgust (duly noted by the jury and even the judge). This was the same trial about which the plaintiff’s attorney had called me 1 hour before I was due to appear in court, telling me that I was excused and did not have to appear. I assured him that I did not trust this information and would be there, despite his advice. The first person I encountered on entering the courthouse was the trial judge, who knew nothing about my being excused. This was plainly Chapter 4 / Physician As a Witness 45 a clever trap, and it would likely have gotten me a citation for con- tempt of court. I can recall once having set off a barrage of hostility from the questioning attorney and, wanting to make everyone posi- tively aware of this, I apologized that I had embarrassed him uninten- tionally and publicly on his own ground and in front of his client, his colleagues, and even the judge. It is difficult to cite or recommend a role model for the expert on the witness stand. I like to think that Andy Griffith, in his classic motion picture No Time for Sergeants, is very nearly the ideal, if not over- done. He made every effort to be cooperative, and his pleasant and good-natured spirit always came through, never failing to irritate those who were trying to take advantage of him. One must be careful not to appear either wise or a smart aleck on the stand. This will irritate everyone and will cave in on whomever attempts to use it. Any temporary victories by an expert witness will be short-lived under the withering stare of an experienced judge. Also remember that the attorney who engaged your services is in charge of working out the strategy for the case presentation. The cleverest and best plan is of little use if it is brought up at the wrong time or out of sequence or if it is at cross-purposes with the strategy of the experienced attorney. You should discuss your ideas and sug- gestions with him or her and follow instructions.
One is that the underlying coding is correct but it is the noradrenergic response evoked by the stimulus that is inappropriate purchase 180mg allegra otc. A second is that the amplitude of the noradrenergic response to arousing stimuli is normal but the underlying coding is not effective allegra 120mg. For instance generic allegra 180mg visa, an early report suggested that there is a positive correlation between the density of (postsynaptic) b-adrenoceptors in rat cortex and behavioural resistance to a mild environmental stress (novelty and frustration) but a negative correlation between these parameters when the stress is intensified (Stanford and Salmon 1992). Evidence suggests that the relationship between these two parameters is described by a bell-shaped curve and so an optimal phasic response is manifest only at intermediate levels of tonic activity (Rajkowski et al. Obviously, it is extremely unlikely that noradrenergic transmission is the sole factor to determine the behavioural response to even simple environmental stimuli. Indeed, a bell-shaped dose±response curve immediately suggests the intervention of one or more additional factors (neurotransmitters? Such interactions with other neurotransmitters could well define the relationship between noradrenergic transmission and the coding of the coping response. Either a reduction or an increase in noradrenergic transmission produces a functional mismatch and diminishes coping. In these normal subjects, optimal coping is attained when the noradrenergic response to a specific stimulus corresponds to that marked (^). If there is a leftward shift of the curve that describes the neurochemical coding of coping, then the (predetermined) noradrenergic response that would be optimal in normal individuals now produces suboptimal coping (*). One remedy for such a dysfunction is to reduce noradrenergic transmission so as to restore optimal coping. Similarly, in the case of a rightward shift of the coping curve (c), a predetermined noradrenergic response to a specific stimulus, that would be optimal in normal individuals, will again produce suboptimal coping (*). In both (b) and (c) an alternative way to restore optimal coping would be to reverse the shift in the noradrenergic transmission/coping curve. This could explain the changes in mood that occur after chronic administration of drugs that cause long- latency changes in neurochemical factors that influence noradrenergic transmission (see Chapters 19 and 20) SUMMARY Much remains to be learned about the neurochemical regulation of noradrenergic transmission and even more research is required before we can define the role(s) of this neurotransmitter in the brain. Nevertheless, it is evident that these neurons are a crucial component of the network of monoamine influences on the limbic system and that they 184 NEUROTRANSMITTERS, DRUGS AND BRAIN FUNCTION are capable of both short- and long-term adaptive changes that will influence emotion, motivation, cognition and many other aspects of behaviour. Aston-Jones, G, Rajkowski, J, Kubiak, P and Alexinsky, T (1994) Locus coeruleus neurons in monkey are selectively activated by attended cues in a vigilance task. Bonisch, H, Hammermann, R and Bruss, M (1998) Role of protein kinase C and second messengers in regulation of the norepinephrine transporter. Cederbaum, JM and Aghajanian, GK (1976) Noradrenergic neurons of the locus coeruleus: inhibition by epinephrine and activation by the alpha-antagonist piperoxane. Fassio, A, Bonanno, G, Fontana, G, Usai, C, Marchi, M and Raiteri, M (1996) Role of external and internal calcium on heterocarrier-mediated transmitter release. Fillenz, M (1993) Short-term control of transmitter synthesis in central catecholaminergic neurones. Harley, CW (1987) A role for norepinephrine in arousal, emotion and learning: limbic modulation by norepinephrine and the Kety hypothesis.