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Anatomy and physiology
Published in Suzanne Everett, Handbook of Contraception and Sexual Health, 2020
When a woman is sexually excited the clitoris and the labia minora will become erect, the breasts will enlarge and the nipples erect. The vagina will become lubricated, and this will aid vaginal penetration by the penis. Women achieve orgasm through the stimulation of the clitoris and the cervix; they are able to achieve several orgasms within a short period of time. Orgasm causes the cervix and uterus to contract rhythmically, aiding the aspiration of sperm into the uterus. Orgasm is not necessary for fertilisation. Women do not experience a refractory period, so they may be able to experience repeated orgasms before experiencing resolution.
The Nervous System and Its Disorders
Published in Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss, Understanding Medical Terms, 2020
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss
After a section of nerve has "fired" or become depolarized, it must reestablish its membrane potential or repolarize before another impulse can be transmitted, so it is refractory to further stimulation. During this refractory period, potassium flows outward through the membrane pores to reestablish the potential quickly, and the active transport of sodium continues more slowly to maintain the potential after multiple firings. The refractory period is extremely short, varying in the normal individual from about 1/2500 of a second to 1/250 of a second. The "strength" of a nerve impulse is the combination of the number of firings a second within each nerve cell and the number of nerve cells in a nerve trunk (group of nerve cells packed together in a bundle) that are firing.
Physical Aspects of the Sex Response
Published in Philipa A Brough, Margaret Denman, Introduction to Psychosexual Medicine, 2019
Detumescence is followed by a refractory period, during which the penis remains poorly or totally unresponsive to erectogenic stimuli. This period can last from as short as a few minutes in younger males to as long as days for older males, with the average refractory period being 30 minutes. The refractory period is often accompanied by a reduction or absence of sexual desire and can also be accompanied by penile hypersensitivity, whereby further sexual stimulation may be painful (32).
Flecainide toxicity late after liver transplantation
Published in Baylor University Medical Center Proceedings, 2021
Ossama Elsaid, Kristen M. Tecson, Hafiza Khan, Manish D. Assar
Flecainide is a Vaughn-Williams class IC antiarrhythmic agent indicated for patients with supraventricular arrhythmias without ischemic or structural heart disease. It exerts its action through blocking open-state sodium channels and delaying phase 0 depolarization, slowing conduction in the atrium, His-Purkinje system, and ventricles. This can result in suppressing sinoatrial node automaticity and slowing the conduction. It can increase the refractory period in ventricular tissue.1 Flecainide is primarily metabolized by the hepatic cytochrome P450 CYP2D6 system; 30% is excreted in urine unchanged. The elimination half-life ranges from 7 to 23 hours, but may take 58 hours, with a 40% drop in total clearance of the drug in renally impaired patients.2,3 Flecainide toxicity is rare and carries a mortality rate of 10%. It can be precipitated by renal and liver failure; hyponatremia may contribute to cardiac toxicity by increasing the competitive inhibition of flecainide on sodium channels.4,5
Challenging the Standard Model of Sexual Response: Evidence of a Variable Male Sexual Response Cycle
Published in The Journal of Sex Research, 2020
Dean M. Busby, Nathan D. Leonhardt, Chelom E. Leavitt, Veronica Hanna-Walker
Even though the lack of a distinction between the arousal and desire constructs for men was consistent with the findings from previous studies on women and their sexual response cycles (Basson, 2008; Leavitt, Leonhardt, et al., 2019), the findings from the current study are distinct. The most important distinction between the two genders is that in this study the lowest arousal group was still in a medium range, whereas in Leavitt, Leonhardt, et al.’s 2019’s study (2019) 8% of the sample of women were in a very low arousal group that had substantially lower scores on all outcome measures. The other difference noted in the patterns of arousal between men in this study and women in Leavitt, Leonhardt, et al.’s study (2019) is that men in general had a more substantial drop in arousal at the end of their experience than women, verifying the reality of a refractory period for them (Seizert, 2018).
Changes in nerve excitability indices in hereditary transthyretin amyloidosis
Published in Amyloid, 2019
Taro Yamashita, Mitsuharu Ueda, Sonoko Misawa, Yasuteru Inoue, Teruaki Masuda, Yohei Misumi, Kotaro Takamatsu, Konen Obayashi, Satoshi Kuwabara, Yukio Ando
The strength duration time constants (SDTCs) in patients with ATTRm amyloidosis (mean 0.43 ± 0.10, median 0.41, range 0.18–0.51) tended to be shorter than those in control subjects (mean 0.48 ± 0.07, median 0.48, range 0.41–0.57) (reduced excitability, decreased persistent sodium current) (Figure 1(A,C,D)). The slope of the curve for threshold change versus stimulus width (rheobase) in the patients tended to be higher than that in control subjects (reduced excitability) (Figure 1(A)). The threshold reduction in hyperpolarizing threshold electrotonus (TE) in the patients tended to be larger than that in control subjects (fanning out, increased threshold, hyperpolarization; S2 phase: abnormal slow potassium channel, hyperactivity of the sodium–potassium pump) (Figure 1(B)). The SDTCs in patients with ATTRm amyloidosis were weakly and inversely correlated with the duration of disease (Figure 1(C)). The hyperpolarizing current–threshold (I/V) slope in motor axons in the patients tended to be higher than that in control subjects (Figure 1(E)). The relative refractory period of the patients was prolonged compared with that of controls (Figure 1(F)).