Think Essays

Health and Illness

There's this prevailing misconception if one asks people around.  When one says 'Mental illness', one will immediately imagine the straight jackets, the cushioned walls of a mental asylum and generally people throwing violent tantrums.  Any kind of mental illness, from the most common, normal and habitable, falls in this category.  The fault to blame is mass media and its portrayal of people under mental illness.  Stereotype, bias and prejudice arise as murderers and villains are associated with this disease.  The idea of mentally ill people as evil, malicious and extreme is easily formed out of this.  Immediately, the patients inspire repugnance and disgust that displaces and dehumanizes them.   

One may also point the blame to the institutionalizing of mentally ill patients.  Society was horrified when some mentally ill criminals emerged and commit the most heinous, disturbing and unspeakable crimes that it decided to contain them in a ward called the mental institution in order to prevent them from causing further violent acts.  Because of such shocking crimes reported in the media, the public was easily led to believe that the mentally ill patients are among the most violent people existent.  These crimes, while only occurring at a rare and small rate, was enlarged in gigantic epic proportions thanks to being published in Headlines and broadcasted in evening news all over.  It became the general belief that the violence will be lessened and removed if the mentally ill patients are all contained in one place so that the public may be protected. 

 

The lack of proper information and the dominance of misleading presentation of the mentally ill have provided a negative portrayal on the concept of mental illness.  People who are deemed mentally ill are taken into a collective of unjustified and rejected categorization.  This does not only lead to the maltreatment and misperception of these people, they are also subjected to acts that would deliberate isolate and single them out.  For instance, some mentally ill patients who have minor symptoms are immediately confined in mental hospitals as this is the general presumption of where mentally ill, indiscriminant of range of severity, should be placed.  Sadly, authorities themselves from the medical field to that of the government share the fear and distancing that they should be trying to correct.  In the part of the families of the mentally ill, there is an added pressure and doubts to what they can do.  With the dominating discrimination on the mentally ill, the patient and their families do not know where and who they can turn to.  The general reaction then, is to avoid and push them away (and allow them to worsen in their symptoms) rather reach out to them and help them be better.  

 

It will be difficult for the mentally ill patients to have the proper treatment if the people closest to them would refuse them.  Their family for instance plays a significant role in their condition.  If the mentally ill patient should be pressured by biases and fears brought by societal perceptions, there will only be suffering.  Caring for the mentally ill has brought about negative social interactions, distress and depression.  In contrast, the tolerant and accepting treatment and perception of these patients would ultimately lead to an environment welcoming of recovery.   

 

Needless to say, mental institutions, the product of the public's clamor for protection against the mentally ill as they are perceived to be violent, had become a failure in treating this illness.  The mainstreaming of the mentally ill as criminals did very little to contribute to this growing phenomenon.  It remains true that most of the mentally ill patients are not at all inclined to violence unless they are pressured and pushed to do so which institutions may just bring due to its inhumane treatment.  All that has been achieved in the past is that mentally ill patients are victims because they are perceived to be overly difficult, dangerous, fearsome, and incomprehensible.   In this time, it is proper to break away from such conventions and started considering what the mentally ill patients really think.  It is also time to prepare medical practitioners as to how to confront rather to avoid this increasing problem.  Society for this part needs to understand people as part of their own and not any different.  With support, there is a large chance for these mentally ill patients to rejoin society and function in this in a manner that will benefit it in the long run. 

 

I am one of the people who have believed fervently that mentally ill people are possibly the most violent and dangerous people around.  Informed by the movies, by television, by newspaper headlines and mass media as a whole, I have also spurn a fear and a rejection of mentally ill patients.  If I see them in the streets, I immediately go the other way.  My perception of them has always been evil heartless individuals who are driven completely and irreconcilably into madness.  I always wish that they are all confined forever in institutions.  Should a person near me become mentally ill, my prerogative is avoidance at all cost.

 

However I had soon realized that anyone can actually be inflicted with a mental disease.  Friends that I know have been consulting psychiatrists and have been diagnosed as having mental illness despite the fact that I do see them as having normal behavior.  Similarly, the media had began to explore the lives and the circumstances of people who are schizophrenic and autistic among others in many manners that shown them to be acceptable and actually sympathetic people.  Recently, my cousin had given birth to an autistic child and I realize how very much prevalent mental illness can be.  I began to understand what causes these mental illnesses and how natural they are, after all.  I began to see mentally ill patients as people like the rest of us.  There is always a reason why they are that way and they should not be blamed of their circumstances at all.  In fact I have learned that I should understand and reach out to them because they are real good people, ordinary as I am and they need help.  By helping them, they can perform regular daily lives and ultimately attain happiness as every human being deserves to have. 

 

Organizational Success

            This paper will try to discuss and present evidences that support the idea that the transformation of the human resources into a valuable asset is a one of the key issue of strategic management in the service sector. It will also try to highlight and evaluate the significance of the term strategic human resources management.

            One evidence that points out to the transformation of the human resources as one of the key issues of strategic management is due to certain challenges that is currently facing human resources. Since organizations and business companies need able and effective pool of employees, human resources must be well suited and must conform to the structure of the organization. Human resources as pointed out by Lawler is must be developed in such a way that would enhance the performance, training, career and selection of old and new employees of a company in order to step up its advantages. He further stated that there are five specific aspects that challenge human resources development.

            One challenge is in organizing and achieving high performance. Mohrman believed that in creating small, flexible, cross functional units and aligning people around value-added task rather than overhead task, outsourcing and partnering will be successful if there is a high level of motivation that is present in the workforce. Concerns regarding the condition of the workforce remaining after downsizing, reengineering, and cutbacks must also be addressed. Above average performance is only possible when an organizational form is developed that is designed to incorporate the nature of the task assigned to the employees an the qualifications and characteristics of the employee themselves. In this approach, human resources development personnel must develop a comprehensive understanding with regards to strategy, goals, and motivations of employees that would provide the extra boost in the output of the company.

            There must also be proper and strategic deployment of employees because workers tend to move in a series of projects rather that in organized and prearranged order of jobs and process. The manager must possess an understanding with regards to the weaknesses and strong points acquired by an employee and how the company can maximize these talents and traits. It is therefore possible to use new compensation and rewards system to attract, develop, motivate and retain the workforce. A proper management of organizational competencies and capabilities must also be accessed. Lake pointed out that management of human resources competencies and organizational capabilities are task that are significant in the survival of the company. Organizations are required to constantly update and enhance their knowledge base in order to attain a competitive edge in relation to other competitors.

            Organizations nowadays must have skills in group processes and organizational understanding although there is still an emphasis on leaning intervention and other approaches to development. Aside from these, organizational knowledge and learning is also vital. In traditional companies and business organizations, knowledge and learning is shared by the employees through informal networks and person to person interaction but this practice will no longer be viable in today’s world. Companies and business organization must fashion a structural and highly efficient transfer and development of knowledge and learning. Knowledge must be dispersed cross functionally and must be exploited across geographical boundaries. Knowledge sharing and development, distribution of documents and readily available forms, data and statistics are the primary factors that contribute to the success of a business venture.

            There must also be a psychological employment contract that reflects the beliefs and term of an employee concerning organizational member’s responsibilities and expectations from the company. Contract must also cater to different group of people and must address the need of each group. New norms, rules and regulations must be implemented while new ways of contracting for work must be devised.

            Other writers and researchers meanwhile underlined different evidences that points to the transformation of human resources. These are: building and operating an effective customer-responsive organization, gearing up in becoming an effective global competitor, competing profitably with lost cost production, transitioning from a profit-through-cost-cutting environment to a revenue-growth environment, effectively taking advantage of new and efficient means of technology, attracting, developing and retaining of new and top level talents and operating internationally without a competitive, pro business industrial policy matching those of foreign competitors.

            Changes and the transformation of human resources is equally affected by the changing business context, a small alteration in the business context can have a reciprocating effect on the state of human resources and its development. Companies are being challenged in to adapt and to modify their human resources in order to be highly competitive against its competitors. Examples of these changing business context are the accelerated pace of business change , reduced cycle time, shifting services while providing total customer solution and total customer retention and satisfaction. Changing business context can also mean operating as a flexible, global and virtual organization relying on partnership, joint ventures and alliances and addressing the needs of service professional and workers while providing the value that they need.

Human resource function has evolved over the decades since it first emerged in the 1920’s. Today, the primary focus of human resources is the development of organizational capabilities required to carry out business strategies. Leaders must grasp that the correlation of strategy, work design, recruiting and staffing can be vital factors that will ensure the success of the company.

Because of this, human resource leaders on each management team play a lead role in achieving this strategic alignment addressing problems or and seizing opportunities that will impact business performance. Leaders serve as guide in the assessment of people-related issues and shaping of people-related strategies to meet business requirements. They directly influence business thinking and action, with the aim of building talent, processes and systems that may give the organization a competitive advantage.

Human resource leaders are expected to lead quantum business change effectively. They help define the business case for change, communicate a vision of the desired future state, shape a sound implementation plan and follow through to achieve sustained results. More than in any past era, HR leaders are expected to be effective change leaders, working in the center of each business, not at the edge of the action. This means they need the business knowledge and acumen, relevant human resource expertise and skills in furthering the change process.

Because HR leaders work as part of a management team, they share accountability for achieving targeted business objectives, including people-related objectives. Peter Drucker once called for the "end of the personnel department," anticipating that "staff will become line by assuming responsibility for business results."

Specialized HR Expertise

The human resource function is also valued as the primary source of knowledge and skill in the people-related areas of strategy implementation - organization and work design, strategic staffing, learning and development, performance management and rewards, employee relations and change management itself. It is no longer sufficient for human resource generalists to counsel and assist managers on a wide range of human resource topics; rather, in-depth, specialized capabilities must be available when and where they are needed.

To address critical issues effectively, managers need creative, effective solutions that tap both external and internal best practices. More important, when HR specialists can develop innovative practices, there is the potential to achieve a competitive advantage - differentiating the company from others through certain extraordinary human resource practices that give the company an edge in business performance.

Human resource specialists may reside anywhere in a company. They may be aligned with business units as part of a team (within HR or not). Sales or technical training or specialized recruiting are often aligned with businesses. They may be shared as consultants working with business units on projects when their expertise is required. They may also be based in other company areas, such as legal affairs or a quality function. They may be external to the company, through specialized consulting and service firms available on call as part of a resource network.

Organizational units or locations typically can no longer cost-justify their own cadre of human resource specialists. The alternative is sharing. Reliance on specialists as needed requires careful definition of the tasks and matching skills to them. It also requires a high degree of trust, collaboration and knowledge sharing. This is particularly challenging as companies share expertise on a wider geographic, even global, basis.

Transparent HR Services and Support

The human resource function provides the systems and services infrastructure necessary to enable the effective management of people across the company on a direct-access, cost-effective basis. Companies trade off the customization of policies and practices that do not build competitive advantage within different business situations in favor of a lower overall cost and improved efficiency and service quality.

Services are becoming transparent to the users. Instead of requiring direct personal interaction, they are provided in new ways, such as through around-the-clock telephone or intranet/Internet access. As a result, they are often more timely, more reliable, more accurate and more responsive to needs.

Instead of being the primary work HR performs, support and services activities (e.g., administration, payroll, benefits, compensation, relocations, policy interpretation, records, legal compliance and reporting and routine transactions) are becoming a smaller part of the work performed in terms of time and resources applied. Many companies report reducing costs of providing services by 40% or more through this change.

The key is leveraging technology to provide services at lower cost, more consistently, with an appropriate standard of quality and with greater speed and efficiency. Typically achieved by leveraging technology, companies have continuously improved their productivity and service quality. Whether the services are provided internally or outsourced is merely a choice. Effective management of operations is the key.

A Community, Not a Department

The traditional human resource function was aligned with a hierarchical business organization, with clear differentiation of staff and line functions. Human resource staff were expected to be responsive and supportive, but line managers were responsible for decisions and outcomes. Strategies and innovations were typically developed centrally and then "rolled out" to company business units and levels. Local human resource staff were commonly generalists charged with implementation and were regarded for their excellence in providing needed human resource services in a quality, responsive manner.

The new human resource function is a virtual organization. Today, and into the 21 st century, human resource functions concentrate resources and activities where they will have the desired business impact. Centralization and decentralization are no longer relevant concepts. Strategies and innovations are increasingly developed within the various business units, within the business context; central services focus on providing operational services and support. The function, as a community, embraces all resources providing people-related services, whether within the human resource organization, within other units (e.g., sales training, legal counsel, or payroll) or provided by external partners or vendors.

The function relies more on networking, temporary project teams spanning functions and business units and external resources. In several large companies, the corporate HR VP has virtually no dedicated resources or budget; resources are embedded in business units, and shared services are funded through business unit allocations and charge-backs. As a result, the operating plan and budget of the human resource "department" are less relevant, as are ratios of HR head count to employees and the like. Instead, the total picture is drawn to address people-related needs across the business.

The biggest challenge facing human resource staff is getting accustomed to working as a virtual community. Human resource professionals have been reluctant to rely on vendors or shared services. Once comfortable with resources and controls at hand, they find it difficult to rely instead on influence, collaboration, trust and shared responsibility. The more rapid pace, increased ambiguity and complexity inherent in working in this new environment is difficult to embrace. Many will not make the transition.

Implementation

The 21 st century business context requires HR to become more virtual, more nimble, more efficient in providing operational services and more effective in building organizational capabilities necessary to gain and sustain competitive advantage. What has been your experience? What are your views?

 

Angiography

            This paper discusses about the differences between Computed Tomography Angiography and Conventional Angiography in terms of quality and reliability.  The two are compared and contrasted based on their characteristics.

           

Diseases in blood vessels including those of the brain and the heart can be diagnosed through angiography. Angiography is used to diagnose pathology of blood vessels such as blockage caused by plaque build up. Traditionally, X-ray or the conventional angiography was used but due to the development of technology, Magnetic Resonance, ultrasound, and Computed Tomography slowly replaced x-ray angiography.

            Basically, angiography is a radiographic technique where a radio-opaque contrast material is injected into a blood vessel for the purpose of identifying anatomy on x-ray. This technique is used to image arteries in the brain, heart, kidneys, gastrointestinal tract, aorta, neck or carotids, chest, limbs and pulmonary circuits. This technique is carried out in a laboratory by a trained cardiologist or radiologist and technicians. The doctor will first need to insert an intravenous, IV, line into one of the blood vessels of the patient’s arm, chest, neck or groin. Then, a catheter is inserted through the IV and into the patient’s blood vessels using x-ray machine that produces real-time pictures. When the catheter is already placed into the blood vessel of interest, contrasts material is injected and pictures are taken. It usually takes time for the doctors to get the catheter into the right spot. There are different types of angiography depending on the type of test such as cerebral angiography for the head, extremity angiography for arm or leg, renal angiography for the kidneys and pulmonary angiography for the lungs.

            Conventional angiography or cardiac catheterization is the diagnostic of standard for determining the presence, location, and severity of coronary artery disease. Conventional angiography has long been used in the medical field for its high effectiveness. However, this technique is invasive, labor intensive due to its procedure, costly and has a significant risk of complications. This technique involves passing a catheter onto the right or left side of the heart. It is also used to determine pressure and blood flow in the heart’s chambers, collect blood samples from the heart and examine the arteries of the heart with an x-ray technique called fluoroscopy. Fluoroscopy provides real-time visualization of the x-ray images on a screen and provides a permanent record of the procedure.

            Conventional angiography carries risks depending on organ undergoing a test. These risks may include bleeding and pain at IV site; a risk that the soft plastic catheters could damage the blood vessels; the risks the blood clot could form on the catheters and later block blood vessels in the body; and the risks that the contrast material could damage the kidneys especially in diabetes patients, aside from some discomfort and it mandates routine follow-up care.

           

On the other hand, there are other angiography techniques that are more advantageous than the conventional type. One of these is the Computed Tomography Angiography, CTA. CTA is replacing conventional angiography because this test is less invasive and easier to perform than conventional angiography while obtaining results just as accurate as the results obtained from conventional angiography. CTA is a three-dimensional technique that provides information about the imaged vessels and adjacent structures. It enables the display of vascular structures aided by injections of contrast medium. The multislice scanner enables the system to display the entire vascular system including small vascular exits, branches, embolisms or dissection membranes. This is one of the advantages of CTA, with this type of imaging the physician can easily conduct and decide for surgical planning using the image produce through a CTA.

CTA requires only venous vascular access and is an outpatient examination with lesser risks than conventional angiography. At minimum, CTA requires a thin section helical CT acquisition coupled with a power injection of intravenous iodinated contrast medium. A multidetector-row CT or MDCT, that is capable of detecting and reliably diagnosing pathology in the adjacent structures and end organs of the vessel is commonly used and preferred for CTA. For cardiac and some aortic CTA, an electrocardiograph-gated acquisition should be performed that allows retrospective reconstruction of the scan volume at multiple phases through the cardiac cycle. The advantages of Computed Tomography angiography over conventional angiography were studied by the American Heart Association, and found out that the advantages and use of CTA varies depending on the type of disease being evaluated. For occlusive disease of the extracranial carotid arteries, CTA has higher degree of accuracy compared with conventional angiography. For thoracic aorta, one major advantage of CTA is the ability to accurately evaluate the surrounding structures within the thorax for pathology that may provide alternative explanations for the patient’s symptoms necessary for the treatment. For abdominal aorta diseases, CTA has high accuracy in measuring vessel lengths, diameters and angles. With peripheral arterial disease, CTA can produce image not visualized by conventional angiography aside from the greater longitudinal coverage of multidetector-row CT .

Generally, CTA has many advantages over the conventional angiography. These advantages include visualization of the anatomy from multiple angles and in multiple planes; improved visualization of soft tissues and other adjacent anatomic structures; less invasiveness and fewer complications. However, it is still a standard for coronary artery diseases to use the conventional angiography or the Cardiac Catheterization because there is still no sufficient evidence to support the use of CTA with suspected coronary artery disease. CTA also involves radiation exposure and the potential for ionated contrast related reaction  as well as temporal and spatial resolution

 

Human Respiratory

INTRODUCTION

Imagine people around you not breathing, for sure the world will not be normal so, the human respiratory system plays a crucial role to the survival of human life in the society where communication takes place. Human respiratory involves various mechanism along with the circulatory system to deliver oxygen from the lungs to the cells and remove carbon dioxide and return it to the lungs to be exhaled. The exchange of oxygen and carbon dioxide between the air, blood and body tissues is known as respiration. It is said that vigorous lungs takes about 1 pint of air about 12-15 times each minute as the blood in the body passed through the lungs every minute.

 

MAIN BODY

Breathing

Thus, breathing process consists of two phases: the inspiration phase that allows air to flow into the lungs and the expiration phase that amicably involves gases leaving the lungs. In the inspiration stage, the diaphragm and intercostal muscles contract allowing air to enter the lungs as in expiration, the inspiration muscles relax forcing gases to flow out of the lungs. Thus, breathing is an automatic process controlled by the respiratory center in the brain. Intercostal muscles around the chest cavity are stimulated by the medulla, causing them to contract and relax. The intercostal muscles increase thoracic volume by raising the top border of the thorax, while the diaphragm increases it by lowering the bottom border of the thorax as it contracts and relaxes that will draw air into and forces air out of the lungs as the flow of air occurs only when there is a difference in pressure. Air naturally flows from a region of high pressure to one of low pressure, and the bigger the difference in pressure, the faster the flow.

The intercostal muscles are located between the ribs. There are two kinds of intercotal muscles: internal and external. The intercostal muscles are controlled by the medulla.  The internal intercostal muscles are located on the inside of the ribs and extend from the front of the ribs, around back and past the bend in the ribs. The external intercostal muscles are located on the outside of the ribs, and wraparound the back of the ribs. The diaphragm is the muscular partition located between the chest cavity and the abdominal cavity. It plays a major role in respiration. During inspiration, the diaphragm descends, the inspiratory muscles contract, and the rib cage rises. During expiration, the diaphragm rises, the inspiratory muscles relax, and the rib cage descends.

 

Available at:

The average pair of human lungs can hold about five litres of air, but only a small amount is used during normal breathing. Different lung volumes and capacities measure various features about the lungs. These volumes vary with the age and height of the person. The values here are for a 70 kg, average-sized adult male:

 

Total lung capacity (TLC) whivh is about five litres all the air the lungs can hold.

Vital capacity (VC) The maximum volume of air that can be expelled at the normal rate of exhalation after a maximum inspiration

Tidal volume (TV) is the amount of air breathed in or out during normal respiration. It

Residual volume (RV) is the amount of air left in the lungs after a maximal exhalation.

Expiratory reserve volume (ERV) is the amount of additional air that can be breathed out after normal expiration.

Inspiratory reserve volume is the additional air that can be inhaled after a normal tidal breath in.

Functional residual capacity (ERV + RV) is the amount of air left in the lungs after a tidal breath out.

Inspiratory capacity (IC) is the volume that can be inhaled after a tidal breath out.

Anatomical dead space is the volume of the airways.

Factors affecting lung volume

The breathing mechanisms in mammals is called Tidal Breathing. Tidal breathing means that air goes into the lungs the same way that it comes out. The total lung capacity depends on the person's age, weight, sex and the degree of physical activity. For example, females tend to have a 20–25% lower capacity than males. Tall people tend to have a larger total lung capacity than shorter people. Heavy smokers have a drastically lower capacity than nonsmokers. Lung capacity is also affected by altitude. A person who is born and lives at sea level will have a smaller lung capacity than a person who spends their life at a high altitude. This is because there is less oxygen in the air at altitude, so the lungs gradually expand to process more air.

 

Gas Exchange within the Lungs - Bronchi, Bronchioles and Alveoli

Bronchi and Bronchioles

The air from the bronchi passes into the smaller airways called the bronchioles, and then into the alveoli. The alveoli are tiny air sacs at the ends of the bronchioles. It is within the alveoli where the oxygen from the air enters the blood, and carbon dioxide from the blood enters the lungs.

Alveoli

The blood barrier between the alveolar space and the pulmonary capillaries is very thin to allow for rapid gas exchange. During inspiration, oxygen diffuses through the alveoli walls and the interstitial space, into the blood. Carbon dioxide diffuses in the opposite direction during exhalation. Alveoli are smaller than grains of salt, with approximately 300 million alveoli in each lung. Although alveoli are tiny structures, they have a very large surface area in total for performing efficient gas exchange.

People can say that pulmonary ventilation may arguably be the most important process of respiration, in that, its function is to continually renew the air content within the lungs. Without continual renewal of the air content in the lungs, the oxygen that is available for respiration and energy conversion would be depleted quickly. For our purposes, we will separate the anatomy of the lungs into two zones. The conducting zone is the portion of the lungs that aids in the movement of air in and out of the surrounding environment, and sets the initial availability of air to move into the respiratory zone. In the conducting zone, no gas exchange occurs.

The respiratory zone is the portion of the lungs that includes the alveoli and capillary plexus and is the site where initial gas exchange between the lungs and blood occurs. In this lesson we will learn how each of these zones are ventilated. To move air into the lungs, a negative pressure differential occurs when the diaphragm contracts downward, allowing the lungs to expand with air. This action is known as inspiration. The movement of air from the lungs to the ambient environment is accomplished when a positive pressure differential occurs, as the diaphragm relaxes, increasing the pressure in the lungs and forcing air out of the nose and mouth. This action is known as expiration. As ventilation occurs, ambient air is moved from the atmosphere into the lungs, and then from the lungs back into the ambient environment.

The function of the respiratory zone of the lungs is to provide concurrent gas exchange of O₂ and CO₂ between the lungs and blood. The act of inspiration brings the necessary O₂ into the respiratory zone and the act of expiration removes the CO₂ from the respiratory zone. The respiratory zone consists of the alveoli and capillary plexus. Each alveolar sac in the lung has contact with the capillary plexus. It is at the junction of the alveoli and capillary plexus where O₂ is exchanged from the alveoli to the blood and CO₂ is exchanged from the blood to the alveoli. The process of gas exchange in this area as well as throughout the body is completed by simple diffusion. Ventilation also acts as the end process to remove carbon dioxide from the body and put it back into the atmosphere in expiration. It is safe to assume that for every liter of inspired ambient air, the O₂ content of that air will consist of 209.3 ml of O₂. People can assume that the greater volume of air that we inspire in a single breath will increase the availability of O₂ for respiration. 

Tidal Volume and Oxygen Capacity

The volume of air that an individual ventilates in one breath is known as the tidal volume (V_T), and maximum V_T is limited to an individual's lung volume. Normal total lung capacities/volumes for the average human are approximately 6 liters for males and 4 liters for females. The lungs however, retain a residual volume (RV) of air necessary to keep the lungs inflated and aid in oxygen transport during the time intervals between breaths. Approximately 20% of the total lung capacity (TLC) consist of the residual volume. This means that the maximal tidal volume (V_T) for a male with a 6 L TLC is 4.8 liters:  6 L * 0.8 = 4.8 L Conversely, the maximal tidal volume (V_T) for a female with a 4 liter TLC is 3.2 liters: 4 L * 0.8 = 3.2 L and that the greatest amount of O₂ available to a male during a single ventilatory cycle (breath) would be: 4.8 L * 0.2093 = 1.004 L O₂ The greatest amount of O₂ available to a female during a single breath would be: 3.2 L * .2093 = 696.7 ml. If oxygen is necessary for energy conversion in aerobic metabolism, then the same time element must be involved. Therefore, we must think in terms of liters/minute or ml/minute when discussing ventilation and respiration. You have learned, thus far, that the maximal V_T for a single ventilatory cycle is dependent on the TLC and the RV of the individual. To further understand the availability of O₂ for energy conversion, you must include the number of ventilatory cycles during a minute. Ventilatory frequency (f) is the term that describes the number of breaths taken in one minute. As frequency of breaths increase the rate of air movement in and out of the lungs increases. Ventilatory frequency for most healthy individuals is approximately 12 breaths per minute at rest and can range from 15 breaths per minute for light exercise, up to 60 breaths per minute during all out maximal effort. Minute ventilation for a healthy individual can range from approximately 6 L/min at rest to above 200 L/min during all out maximal effort depending on the lung volume, breathing patterns, and body size of the individual. At this time I should point out that this description of V_E is describing the ventilation of the lungs as a whole, meaning that V_E incorporates both the conducting zone and the respiratory zone. To determine how V_E is affected by breathing patterns.

Alveolar Ventilation and Residual Volume

The respiratory zone is where gas exchange occurs, so we need ventilation of the alveoli for gas exchange. Alveolar ventilation (V_dotA) is the movement of air in and out of the alveolar sacs. This does not mean that ALL of the air is expelled from the alveoli during expiration. Remember, we have a Residual Volume of air that keeps the lungs inflated and aids in gas exchange between breaths. A small portion of the RV remains in the alveoli at all times for the purpose of gas exchange between breaths, however, the greater portion of the RV is contained in the anatomical dead space (V_D) of the conducting zone. The air that remains in the V_D acts as a buffer by mixing with newly inspired air and protects the alveolar air from severe fluctuations in mixed gas concentrations during inspiration through protecting from severe fluctuations in air concentrations in the alveoli, the V_D allows for consistency of blood gas composition during minute ventilation.