By D. Umul. Appalachian State University.
The structures of the male reproductive system can be catego- Objective 3 Distinguish between primary and secondary rized on a functional basis as follows: sex organs purchase actonel 35 mg online. The primary sex organs are called go- nads; specifically, the testes in the male. Gonads produce Unlike other body systems, the reproductive system is not essen- the gametes, or spermatozoa, and produce and secrete sex tial for the survival of the individual; it is, however, required for hormones. The secretion of male sex hormones, called an- the survival of the species. It is through reproduction that addi- drogens, at the appropriate times and in sufficient quanti- tional individuals of a species population are produced and the ties causes the development of secondary sex organs and genetic code passed from one generation to the next. Secondary sex organs are those ual reproduction, in which genes from two individuals are com- structures that are essential in caring for and transporting bined in random ways with each new generation, offers the spermatozoa. The three categories of secondary sex organs overwhelming advantage of introducing great variability into a are the sperm-transporting ducts, the accessory glands, and population. This variability of genetic constitution helps ensure the copulatory organ. The ducts that transport sperm in- that some members of a population will survive changes in the clude the epididymides, ductus deferentia, ejaculatory ducts, environment over evolutionary time. The male accessory reproductive glands are The reproductive system is unique in two other respects. The penis, which contains erectile tissue, is the cop- “turned on” at puberty by the actions of sex hormones sets the re- ulatory organ. Secondary sex characteris- other organ systems of the body exhibit slight sexual differences, tics are features that are not essential for the reproductive no other system approaches the level of dissimilarity of the repro- process but are generally considered sexual attractants.
The enzyme responsible for this metabolic product purchase 35mg actonel free shipping, CYP2D6, shows genetic polymorphism and so it is possible that the accumulation of mCPP is more problematic in some individuals than others. Ultimately, agonist drugs that directly activate monoamine receptors would appear to be a logical development in this field. Unfortunately, the peripheral side-effects of such compounds could well limit their acceptability even if we were to discover what subset of receptors to target. NEUROBIOLOGICAL CHANGES INDUCED BY CHRONIC ADMINISTRATION OF ANTIDEPRESSANTS The actions of all the compounds described so far seem to underpin the monoamine hypothesis. Yet an outstanding problem in treating depression is that the therapeutic response is both slow and progressive: a significant improvement usually takes at least 2±3 weeks and sometimes much longer. Obviously, if we are to explain the therapeutic effects of antidepressants, we must search for long-term neurochemical changes that occur after their prolonged administration. NORADRENERGIC TARGETS The first indication that some neurochemical changes developed only after prolonged treatment with antidepressants came from landmarkexperiments carried out by Vetulani 444 NEUROTRANSMITTERS, DRUGS AND BRAIN FUNCTION and Sulser in the mid-1970s (Vetulani et al. They found that repeated, but not a single, administration to rats of any of the antidepressants which were available at that time (i. MAOIs, TCAs, iprindole and even simulated electroconvulsive therapy) attenuated the increase in cAMP in the cerebral cortex induced by b-adrenoceptor agonists. They suggested that antidepressants desensitised b-adrenoceptors by uncoupling the receptor from what is now recognised as the Gs-protein so that it can no longer synthesise the b-adrenoceptor second messenger, cAMP. Shortly afterwards, it was found that this desensitisation was usually paralleled by downregulation of b1-(butnotb2-) adrenoceptors. This action is even shared by repeated electroconvulsive shock(Stanford and Nutt 1982) but not by drugs that are ineffective in relieving depression (e. A logical conclusion from this workwas that depression is caused by hyperresponsive b-adrenoceptors.
In some instances actonel 35 mg low price, verbal brain brought on by certain conditions, communication is severely impaired, and even though there are no permanent in other cases it may be totally unaffect- changes in brain function. Some individuals may have limited tions such as meningitis (infection of the mobility or ambulation problems; others covering of the central nervous system), may have signiﬁcant difﬁculty with mobil- diabetic coma, hypoxia (too little oxygen ity or ambulation. Whereas some individ- to the brain), and drug intoxication or uals will be ambulatory, others may withdrawal can all cause temporary dis- require a wheelchair. In some instances turbed brain function resulting in a individuals may have difﬁculty concen- seizure. If the underlying cause of brain trating or remembering, and in other dysfunction is reversible so that no perma- instances individuals’ cognitive abilities nent alteration of brain function exists are unaffected. The term social skill, when individuals have difﬁcul- epilepsy is reserved for individuals with ty in this area, social skills training may recurring seizures and with a chronic be beneﬁcial (Salkever, 2000). Matching abnormality of the brain that results in the work setting to the individual’s specif- seizures. Conditions Affecting the Brain 61 Classiﬁcation of Seizures dergoes rapid, jerky movements. The teeth are clenched tightly together and Individuals with epilepsy can exhibit a control of the bladder or the bowel may be variety of seizures with varying symptoms, lost. The seizure generally lasts less than ranging from muscle spasms or confusion a few minutes. Seizures can sciousness is gradually regained, but indi- be mild or severe, can occur frequently or viduals may experience confusion, rarely, and can change their pattern of difﬁculty in speaking, and headache. Depending on the though postseizure symptoms usually dis- type, seizures usually last only seconds to appear within several hours, the fatigue minutes. Between seizures most individ- experienced may be overwhelming, often uals are able to function normally. Classiﬁcation of seiz- Table 2–5 Common Types of Seizures ures is important so that appropriate man- Associated with Epilepsy agement and treatment can be determined.