Contemporary views on the future of physiology-a report from the 2019 P-MIG focus group.

Physiologists are seen as professionals with a unique understanding of life, health, and disease, essential to the progression of knowledge regarding human functions and health. Among these experts however, the thematic of the "Future of Physiology" has been regularly present in the agenda of physiology organizations around the world as various uncertainties about teaching and research in human physiology emerged. The Physiology Majors Interest Group (P-MIG) 2019 meeting provided the occasion for some strategic reasoning and planning, aiming to identify the trends that might drive future changes in human physiology. Twelve physiologists, all experts in different areas of Physiology research and teaching, nearly all based in North America, volunteered to participate in this focus group. The session was audio recorded. A verbatim transcript of the recording was then analyzed through thematic analysis, aiming to identify the most relevant themes for the future of Physiology and how these themes might unfold. The group concluded that a shared consciousness on general goals is present, meaning to preserve and develop the interdisciplinary/integrative nature, to promote more innovative teaching/learning practices, and to acknowledge technology as the main catalyst for research and teaching innovation and progress. This consciousness was present in all participants. The group also concluded that transformation will likely need to be more effective, and should involve the Physiological Societies and organizations around the world. Special emphasis was placed on the need to share common competences for curriculum definition, common guidance for teaching practice, and common assessment procedures, with particular attention recommended toward science communication.

Heartbeats entrain breathing via baroreceptor-mediated modulation of expiratory activity.

NEW FINDINGS: Cardio-ventilatory coupling refers to the onset of inspiration occurring at a preferential latency following the last heartbeat (HB) in expiration. According to the cardiac-trigger hypothesis, the pulse pressure initiates an inspiration via baroreceptor activation. However, the central neural substrate mediating this coupling remains undefined. Using a combination of animal data, human data and mathematical modelling, this study tests the hypothesis that the HB, by way of pulsatile baroreflex activation, controls the initiation of inspiration that occurs through a rapid neural activation loop from the carotid baroreceptors to Bötzinger complex expiratory neurons. ABSTRACT: Cardio-ventilatory coupling refers to a heartbeat (HB) occurring at a preferred latency prior to the next breath. We hypothesized that the pressure pulse generated by a HB activates baroreceptors that modulate brainstem expiratory neuronal activity and delay the initiation of inspiration. In supine male subjects, we recorded ventilation, electrocardiogram and blood pressure during 20-min epochs of baseline, slow-deep breathing and recovery. In in situ rodent preparations, we recorded brainstem activity in response to pulses of perfusion pressure. We applied a well-established respiratory network model to interpret these data. In humans, the latency between a HB and onset of inspiration was consistent across different breathing patterns. In in situ preparations, a transient pressure pulse during expiration activated a subpopulation of expiratory neurons normally active during post-inspiration, thus delaying the next inspiration. In the model, baroreceptor input to post-inspiratory neurons accounted for the effect. These studies are consistent with baroreflex activation modulating respiration through a pauci-synaptic circuit from baroreceptors to onset of inspiration.

Menstrual Cycle Phases Influence on Cardiorespiratory Response to Exercise in Endurance-Trained Females.

The aim of this study was to analyse the impact of sex hormone fluctuations throughout the menstrual cycle on cardiorespiratory response to high-intensity interval exercise in athletes. Twenty-one eumenorrheic endurance-trained females performed an interval running protocol in three menstrual cycle phases: early-follicular phase (EFP), late-follicular phase (LFP) and mid-luteal phase (MLP). It consisted of 8 × 3-min bouts at 85% of their maximal aerobic speed with 90-s recovery at 30% of their maximal aerobic speed. To verify menstrual cycle phase, we applied a three-step method: calendar-based counting, urinary luteinizing hormone measurement and serum hormone analysis. Mixed-linear model for repeated measures showed menstrual cycle impact on ventilatory (EFP: 78.61 ± 11.09; LFP: 76.45 ± 11.37; MLP: 78.59 ± 13.43) and heart rate (EFP: 167.29 ± 11.44; LFP: 169.89 ± 10.62; MLP: 169.89 ± 11.35) response to high-intensity interval exercise (F2.59 = 4.300; p = 0.018 and F2.61 = 4.648; p = 0.013, respectively). Oxygen consumption, carbon dioxide production, respiratory exchange ratio, breathing frequency, energy expenditure, relative perceived exertion and perceived readiness were unaltered by menstrual cycle phase. Most of the cardiorespiratory variables measured appear to be impassive by menstrual cycle phases throughout a high-intensity interval exercise in endurance-trained athletes. It seems that sex hormone fluctuations throughout the menstrual cycle are not high enough to disrupt tissues' adjustments caused by the high-intensity exercise. Nevertheless, HR based training programs should consider menstrual cycle phase.

Physiology educators find community in the Physiology Majors Interest Group.

The Physiology Majors Interest Group (P-MIG) is a grass-roots consortium of physiology educators with the common interest of creating program-level guidelines for undergraduate physiology and related programs. A key component of the consortium's activities are the annual P-MIG conferences that have been held at different universities over the past 3 yr (Michigan State University, 2017; University of Arizona, 2018; and University of Minnesota, 2019). Postconference surveys indicate that the conferences are highly valued by the participants, as they have provided an opportunity to get to know others who are passionate about undergraduate education, to discuss best practices in program and course delivery, and to form working groups with the goal to develop national and international guidelines for physiology program delivery and assessment.

Evaluation of core concepts of physiology in undergraduate physiology curricula: results from faculty and student surveys.

Unlike other STEM (Science, Technology, Engineering, Mathematics) disciplines, program guidelines for undergraduate physiology degree programs have yet to be firmly established. The purpose of this study was to examine the use of physiology core concepts within undergraduate physiology curricula to discern whether a common subset could be broadly recommended for inclusion in programmatic guidelines. A curricular survey tool was developed to evaluate the depth to which each core concept was included in physiology curricula. Seven self-selected physiology programs assessed core concept inclusion across all courses within the major (0 = not covered, 1 = minimally covered, and 2 = covered to a great extent). The top core concepts ranked by each institution varied considerably, but all were robustly represented across programs. The top five combined rankings for all institutions were as follows: 1) interdependence (1.47 ± 0.63); 2) structure/function (1.46 ± 0.72); 3) homeostasis (1.45 ± 0.71); 4) scientific reasoning (1.44 ± 0.70); and 5) cell-cell communication (1.38 ± 0.75). No common subset of specific core concepts was evident among the seven participating institutions. Next, results were compared with recent Physiology Majors Interest Group (P-MIG) faculty and student surveys that ascertained perceptions of the top five most important core concepts. Three core concepts (homeostasis, structure/function, cell-cell communication) appeared in the top five in more than one-half of survey questions included. We recommend that future programmatic guidelines focus on inclusion of the core concepts of physiology as general models to scaffold learning in physiology curricula, but the programmatic guidelines should allow flexibility in the core concepts emphasized based on program objectives.

Degree requirements of physiology undergraduate programs in the Physiology Majors Interest Group.

Physiology undergraduate degree programs operate in isolation relative to other biological science programs, with little to no understanding of how other institutions structure their course requirements and other degree requirements. The purpose of this report is to preliminarily describe the collective curriculum of physiology programs represented at the Physiology Majors Interest Group (P-MIG) annual meetings from 2018 to 2019. A short preconference survey was sent to attendees that inquired about degree requirements of their respective physiology programs. The requirement for Physiology I (69.2%) with laboratory (66.7%) and Anatomy I (57.1%) with laboratory (42.9%), or combined Anatomy and Physiology I (16.7%) and laboratory (18.2%), were common requirements, but many programs did not require Physiology II (27.3%) or Anatomy II (11.1%). There was nearly consensus on required prerequisites such as Biology (2 semesters with laboratories, 85.7%), Chemistry (2 semesters with laboratory, 88.9%), Physics (2 semesters with laboratory, 75%), Calculus I (61.1%), and Statistics (Biostatistics 42.9%; General Statistics 13.3%). There was less agreement among programs in regards to Calculus II (20.0%), Organic Chemistry (2 semesters, 55.6%), and Biochemistry I (47%), which may be reflective of individual department focus. There was considerable heterogeneity among physiology program course requirements for disciplinary core courses and upper division electives. This report is meant to generate discussion on physiology program curricula in efforts to improve physiology education for majors and assist P-MIG in determining minimal points of consensus as they write the first set of national curricular guidelines for degree programs.

Traube-Hering waves are formed by interaction of respiratory sinus arrhythmia and pulse pressure modulation in healthy men.

Excessive blood pressure variation is linked to the development of hypertension and other diseases. This study assesses the relative role of respiratory sinus arrhythmia (RSA) and pulse pressure (PP) on the amplitude and timing of blood pressure variability with respiration [Traube-Hering (TH) waves]. We analyzed respiratory, electrocardiogram, and blood pressure traces from healthy, supine male subjects (n = 10, mean age = 26.7 ± 1.4) during 20-min epochs of resting, slow deep breathing (SDB), and recovery. Across all epochs, blood pressure and heart rate (HR) were modulated with respiration and the magnitude of RSA; TH waves increased during SDB. The data were deconstructed using a simple mathematical model of blood pressure to dissect the relative roles of RSA and PP on TH waves. We constructed the time series of the R-wave peaks and compared the recorded TH waves with that predicted by the model. Given that cardiac output is determined by both heart rate and stroke volume, it was surprising that the magnitude of the TH waves could be captured by only HR modulation. However, RSA alone did not accurately predict the timing of TH waves relative to the respiratory cycle. Adding respiratory modulation of PP to the model corrected the phase shift showing the expected pattern of BP rising during inspiration with the peak of the TH wave during early expiration. We conclude that short-term variability of blood pressure referred to as TH waves has at least two independent mechanisms whose interaction forms their pattern: RSA and respiratory-driven changes in PP.NEW & NOTEWORTHY Variability in blood pressure has become an important metric to consider as more is learned about the link between excessive blood pressure variability and adverse health outcomes. In this study using slow deep breathing in human subjects, we found that heart rate and pulse pressure variations have comparable effects on the amplitude of blood pressure waves, and it is the common action of the two that defines the phase relationship between respiration and blood pressure oscillations.

From proposal to poster: course-based undergraduate research experience in a physiology laboratory course.

The laboratory course is an excellent venue to apply content, practice inquiry, improve critical thinking, practice key clinical skills, and work with data. The use of inquiry-based course projects allows for students to propose open ended questions, form a hypothesis, design an experiment, collect data, analyze data, draw conclusion, and present their findings. This comprehensive experience is ideal for a capstone (senior level) laboratory course that is the culmination of 4 yr of study in the degree. At Michigan State University, the capstone laboratory has incorporated a formal course-based research experience in human physiology. The rationale and logistics for running such an experience are described in this paper.

Organizing a large-scale Physiology Understanding (PhUn) Week event at a science center.

For the past 6 yr, the Department of Physiology at Michigan State University (MSU) has partnered with Impression 5 Science Center in Lansing, MI. Together, we host a day-long community engagement event on a Saturday each year in early November coinciding with the American Physiological Society's Physiology Understanding Week. The purpose was to provide a fun and memorable hands-on experience for children and families. This paper describes the detailed planning and logistics. The event takes place in the main exhibit space at the science center, generally has 15-17 physiology activities stations set up as booths run by volunteers, and the event runs as an open-house format. Three to five trained volunteers were needed per station for the full day. Since this was primarily based on undergraduate student volunteer involvement (a population already limited for time), morning, afternoon, and/or full-day shifts were offered to accommodate a variety of schedules. Additional set-up, clean-up, and general help was also recruited. Overall, ~100-150 MSU students, faculty, and staff members served as volunteers, alongside Impression 5 staff. Hosting the event at the science center generated a larger audience, aided in advertisement, and allowed for access to a large facility capable of handling the 600-1,000 attendees. The partnership facilitated the sharing of equipment and supplies for physiology demonstrations, allowed for activities on site in the chemistry laboratory space, and facilitated the growth of new community partnerships with local schools and groups who attended the event.

Role of the carotid body chemoreceptors in glucose homeostasis and thermoregulation in humans.

The carotid bodies (CBs) are multi-modal sensory organs located bilaterally at the bifurcation of the carotid artery and innervated by the carotid sinus nerve (Hering's nerve), a branch of the IX cranial nerve. While the CBs (or embryologically analogous structures) are well known as the dominant oxygen-sensing organ in vertebrates, in mammals there is evidence that the CBs may also sense glucose and temperature, and respond to circulating hormones and other factors. Additionally, the CBs likely participate in regulating baseline levels of sympathetic tone. In this brief review, we focus on the evolution of our efforts to understand 'what else' beyond oxygen sensing the CBs do in humans.

Physiology undergraduate degree requirements in the U.S.

Course-level learning objectives and core concepts for undergraduate physiology teaching exist. The next step is to consider how these resources fit into generalizable program-level guidelines for Bachelor of Science (BS) degrees in Physiology. In the absence of program-level guidelines for Physiology degree programs, we compiled a selective internal report to review degree requirements from 18 peer BS programs entitled "Physiology" in the United States (U.S.). There was a range of zero to three required semesters of math, physics, physics laboratory, general biology, biology laboratory, general chemistry, chemistry laboratory, organic chemistry, organic chemistry laboratory, biochemistry, biochemistry laboratory, anatomy, anatomy laboratory, core systems physiology, and physiology laboratory. Required upper division credits ranged from 11 to 31 and included system-specific, exercise and environmental, clinically relevant, pathology/disease-related, and basic science options. We hope that this information will be useful for all programs that consider themselves to be physiology, regardless of name. Reports such as this can serve as a starting point for collaboration among BS programs to improve physiology undergraduate education and best serve our students.