critical thinking questions cardiovascular system

Critical Thinking Questions

• A closed circulatory system is a system in which the blood mixes with the interstitial fluid. Fish have a two-chambered heart. Amphibians and reptiles have a three-chambered heart. Mammals and birds have a four-chambered heart and double circulation.
• A closed circulatory system is a system in which blood is separate from the interstitial fluid. Fish have a two-chambered heart. Amphibians and reptiles have a three-chambered heart. Mammals and birds have a four-chambered heart and double circulation.
• A closed circulatory system is a system in which blood is separate from the interstitial fluid. Amphibians have a two-chambered heart. Fishes and reptiles have a three-chambered heart. Mammals and birds have a four-chambered heart and double circulation.
• A closed circulatory system is a system in which blood mixes with the interstitial fluid. Amphibians have a two-chambered heart. Fishes and reptiles have a three-chambered heart. Mammals and birds have a four-chambered heart and double circulation.
• Blood in a closed circulatory system is present inside blood vessels; it follows a unidirectional path from the heart and around the systemic circulatory route, and then returns to the heart. It is less controlled and structured than an open circulatory system, but it transfers nutrients and waste products more efficiently.
• Blood in a closed circulatory system is not enclosed in blood vessels; it is pumped into a hemocoel, which circulates around the organs, and then reenters the heart through ostia. It is more structured and controlled than an open circulatory system, and it transports nutrients and waste products more efficiently.
• Blood in a closed circulatory system is not enclosed in blood vessels; it is pumped into a hemocoel, which circulates around the organs, and then reenters the heart through ostia. It is less controlled and structured than an open circulatory system, but it transports nutrients and waste products more efficiently.
• Blood in a closed circulatory system is present inside blood vessels; it follows a unidirectional path from the heart around the systemic circulatory route, and then returns to the heart. It is more structured and controlled, and transports nutrients and waste products more efficiently than an open circulatory system.
• In a four-chambered heart, oxygenated blood carried by the left side of the heart is more effectively separated from deoxygenated blood carried by the right side, which assists in more efficient movement of oxygen around the body.
• In a four-chambered heart, oxygenated blood carried by the right side of the heart is more effectively separated from deoxygenated blood carried by the left side, which assists in more efficient movement of oxygen around the body.
• In a four-chambered heart, oxygenated blood carried by the left side of the heart is less effectively separated from deoxygenated blood carried by the right side, which assists in more efficient movement of oxygen around the body.
• In a four-chambered heart, oxygenated blood carried by the right side of the heart is less effectively separated from deoxygenated blood carried by the left side, which assists in more efficient movement of oxygen around the body.
• lymphocytes
• erythrocytes
• Their size and shape allow them to carry and transfer oxygen.
• Their disc shape contains many small vesicles that allow them to carry and transfer oxygen.
• They have nuclei and do not contain hemoglobin.
• They contain coagulation factors and antibodies.
• It is a protein synthesized in the liver.
• It is a liquid that contains only lipids and antibodies.
• It is a blood component that is separated by spinning blood.
• It is an antibody produced in the mucosal lining.
• It is an internal implant that sends an electrical impulse through the heart.
• It is the part of the heart that initiates an electrical impulse, called the sinoatrial node.
• It is the excitation of cardiac muscle cells at the atrioventricular and sinoatrial nodes.
• It is the contracting of muscles that starts in the aorta.
• they beat involuntarily
• they are attached to bones
• they pulse rhythmically
• they are striated

This diagram shows the internal anatomy of the heart.

How would blood circulation beyond the heart be most directly affected if the pulmonary valve could not open?

• Blood could not reach the rest of the body.
• Blood could not reach the lungs.
• Blood could not return from the lungs.
• Blood could not return from the rest of the body.

The diagram shows the internal anatomy of the heart.

How would blood circulation beyond the heart be affected if the tricuspid valve could not open?

• Blood could not enter the pulmonary veins; therefore, it could not reach the lungs.
• Blood could not enter the pulmonary artery; therefore, it could not reach the heart.
• Blood could not enter the pulmonary artery; therefore, it could not reach the lungs.
• Blood could not enter the pulmonary veins; therefore, it could not reach the heart.
• To allow antibodies to enter infected cells and to promote the diffusion of fluid into the interstitial space.
• To assist with gas and nutrient exchange and to prevent the diffusion of fluid into the interstitial space.
• To assist with gas and nutrient exchange and to promote the diffusion of fluid into the interstitial space.
• To allow antibodies to enter infected cells and to prevent the diffusion of fluid into the interstitial space.

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Critical thinking and diagnostic reasoning of the heart and cardiovascular system

Affiliation.

• 1 Advanced Clinical Practitioner-Emergency department, Belfast Health and Social Care Trust.
• PMID: 34761982
• DOI: 10.12968/bjon.2021.30.20.1172

This is the second of two articles exploring assessment and clinical reasoning of conditions relating to the heart and cardiovascular system in the context of emergency care. In the last article, the structure and function of the heart was reviewed, and reference made to many of the conditions that may affect the heart. In addition, the common presenting complaints of cardiac conditions were highlighted, together with important aspects of the history for each symptom. The full cardiac examination was outlined. In this article, some of the common cardiac conditions will be discussed. These will be linked to common findings in the history, examination, and investigations.

Keywords: Acute coronary syndromes; Arrhythmias; Clinical examination; Syncope.

• Cardiovascular System*
• Emergency Medical Services*
• Heart Diseases* / diagnosis

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7.7.10: Critical Thinking Questions

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Describe the function of these terms and describe where they are located: main bronchus, trachea, alveoli, and acinus.

How does the structure of alveoli maximize gas exchange?

What does FEV1/FVC measure? What factors may affect FEV1/FVC?

What is the reason for having residual volume in the lung?

How can a decrease in the percent of oxygen in the air affect the movement of oxygen in the body?

If a patient has increased resistance in their lungs, how can this be detected by a doctor? What does this mean?

How would increased airway resistance affect intrapleural pressure during inhalation?

Explain how a puncture to the thoracic cavity (from a knife wound, for instance) could alter the ability to inhale.

When someone is standing, gravity stretches the bottom of the lung down toward the floor to a greater extent than the top of the lung. What implication could this have on the flow of air in the lungs? Where does gas exchange occur in the lungs?

What would happen if no carbonic anhydrase were present in red blood cells?

How does the administration of 100 percent oxygen save a patient from carbon monoxide poisoning? Why wouldn’t giving carbon dioxide work?

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19.10: Review Questions

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Which of the following is not important in preventing backflow of blood?

• chordae tendineae
• papillary muscles
• endocardium

Which valve separates the left atrium from the left ventricle?

Which of the following lists the valves in the order through which the blood flows from the vena cava through the heart?

• tricuspid, pulmonary semilunar, bicuspid, aortic semilunar
• mitral, pulmonary semilunar, bicuspid, aortic semilunar
• aortic semilunar, pulmonary semilunar, tricuspid, bicuspid
• bicuspid, aortic semilunar, tricuspid, pulmonary semilunar

Which chamber initially receives blood from the systemic circuit?

• left atrium
• left ventricle
• right atrium
• right ventricle

The ________ layer secretes chemicals that help to regulate ionic environments and strength of contraction and serve as powerful vasoconstrictors.

• pericardial sac

The myocardium would be the thickest in the ________.

In which septum is it normal to find openings in the adult?

• interatrial septum
• interventricular septum
• atrioventricular septum
• all of the above

Which of the following is unique to cardiac muscle cells?

• Only cardiac muscle contains a sarcoplasmic reticulum.
• Only cardiac muscle has gap junctions.
• Only cardiac muscle is capable of autorhythmicity
• Only cardiac muscle has a high concentration of mitochondria.

The influx of which ion accounts for the plateau phase?

Which portion of the ECG corresponds to repolarization of the atria?

• QRS complex
• none of the above: atrial repolarization is masked by ventricular depolarization

Which component of the heart conduction system would have the slowest rate of firing?

• atrioventricular node
• atrioventricular bundle
• bundle branches
• Purkinje fibers

The cardiac cycle consists of a distinct relaxation and contraction phase. Which term is typically used to refer ventricular contraction while no blood is being ejected?

• isovolumic contraction

Most blood enters the ventricle during ________.

• atrial systole
• atrial diastole
• ventricular systole

The first heart sound represents which portion of the cardiac cycle?

• closing of the atrioventricular valves
• closing of the semilunar valves

Ventricular relaxation immediately follows ________.

• atrial depolarization
• ventricular repolarization
• ventricular depolarization
• atrial repolarization

The force the heart must overcome to pump blood is known as ________.

• cardiac output
• stroke volume

The cardiovascular centers are located in which area of the brain?

• medulla oblongata
• mesencephalon (midbrain)

In a healthy young adult, what happens to cardiac output when heart rate increases above 160 bpm?

• It increases.
• It decreases.
• It remains constant.
• There is no way to predict.

What happens to preload when there is venous constriction in the veins?

Which of the following is a positive inotrope?

• both Na + and K +

The earliest organ to form and begin function within the developing human is the ________.

Of the three germ layers that give rise to all adult tissues and organs, which gives rise to the heart?

The two tubes that eventually fuse to form the heart are referred to as the ________.

• primitive heart tubes
• endocardial tubes
• cardiogenic region
• cardiogenic tubes

Which primitive area of the heart will give rise to the right ventricle?

• bulbus cordis
• primitive ventricle
• sinus venosus
• truncus arteriosus

The pulmonary trunk and aorta are derived from which primitive heart structure?

1.5 Homeostasis

Learning objectives.

By the end of this section, you will be able to:

• Discuss the role of homeostasis in healthy functioning
• Contrast negative and positive feedback, giving one physiologic example of each mechanism

Maintaining homeostasis requires that the body continuously monitor its internal conditions. From body temperature to blood pressure to levels of certain nutrients, each physiological condition has a particular set point. A set point is the physiological value around which the normal range fluctuates. A normal range is the restricted set of values that is optimally healthful and stable. For example, the set point for normal human body temperature is approximately 37°C (98.6°F) Physiological parameters, such as body temperature and blood pressure, tend to fluctuate within a normal range a few degrees above and below that point. Control centers in the brain and other parts of the body monitor and react to deviations from homeostasis using negative feedback. Negative feedback is a mechanism that reverses a deviation from the set point. Therefore, negative feedback maintains body parameters within their normal range. The maintenance of homeostasis by negative feedback goes on throughout the body at all times, and an understanding of negative feedback is thus fundamental to an understanding of human physiology.

Negative Feedback

A negative feedback system has three basic components ( Figure 1.10 a ). A sensor , also referred to a receptor, is a component of a feedback system that monitors a physiological value. This value is reported to the control center. The control center is the component in a feedback system that compares the value to the normal range. If the value deviates too much from the set point, then the control center activates an effector. An effector is the component in a feedback system that causes a change to reverse the situation and return the value to the normal range.

In order to set the system in motion, a stimulus must drive a physiological parameter beyond its normal range (that is, beyond homeostasis). This stimulus is “heard” by a specific sensor. For example, in the control of blood glucose, specific endocrine cells in the pancreas detect excess glucose (the stimulus) in the bloodstream. These pancreatic beta cells respond to the increased level of blood glucose by releasing the hormone insulin into the bloodstream. The insulin signals skeletal muscle fibers, fat cells (adipocytes), and liver cells to take up the excess glucose, removing it from the bloodstream. As glucose concentration in the bloodstream drops, the decrease in concentration—the actual negative feedback—is detected by pancreatic alpha cells, and insulin release stops. This prevents blood sugar levels from continuing to drop below the normal range.

Humans have a similar temperature regulation feedback system that works by promoting either heat loss or heat gain ( Figure 1.10 b ). When the brain’s temperature regulation center receives data from the sensors indicating that the body’s temperature exceeds its normal range, it stimulates a cluster of brain cells referred to as the “heat-loss center.” This stimulation has three major effects:

• Blood vessels in the skin begin to dilate allowing more blood from the body core to flow to the surface of the skin allowing the heat to radiate into the environment.
• As blood flow to the skin increases, sweat glands are activated to increase their output. As the sweat evaporates from the skin surface into the surrounding air, it takes heat with it.
• The depth of respiration increases, and a person may breathe through an open mouth instead of through the nasal passageways. This further increases heat loss from the lungs.

In contrast, activation of the brain’s heat-gain center by exposure to cold reduces blood flow to the skin, and blood returning from the limbs is diverted into a network of deep veins. This arrangement traps heat closer to the body core and restricts heat loss. If heat loss is severe, the brain triggers an increase in random signals to skeletal muscles, causing them to contract and producing shivering. The muscle contractions of shivering release heat while using up ATP. The brain triggers the thyroid gland in the endocrine system to release thyroid hormone, which increases metabolic activity and heat production in cells throughout the body. The brain also signals the adrenal glands to release epinephrine (adrenaline), a hormone that causes the breakdown of glycogen into glucose, which can be used as an energy source. The breakdown of glycogen into glucose also results in increased metabolism and heat production.

Interactive Link

Water concentration in the body is critical for proper functioning. A person’s body retains very tight control on water levels without conscious control by the person. Watch this video to learn more about water concentration in the body. Which organ has primary control over the amount of water in the body?

Positive Feedback

Positive feedback intensifies a change in the body’s physiological condition rather than reversing it. A deviation from the normal range results in more change, and the system moves farther away from the normal range. Positive feedback in the body is normal only when there is a definite end point. Childbirth and the body’s response to blood loss are two examples of positive feedback loops that are normal but are activated only when needed.

Childbirth at full term is an example of a situation in which the maintenance of the existing body state is not desired. Enormous changes in the mother’s body are required to expel the baby at the end of pregnancy. And the events of childbirth, once begun, must progress rapidly to a conclusion or the life of the mother and the baby are at risk. The extreme muscular work of labor and delivery are the result of a positive feedback system ( Figure 1.11 ).

The first contractions of labor (the stimulus) push the baby toward the cervix (the lowest part of the uterus). The cervix contains stretch-sensitive nerve cells that monitor the degree of stretching (the sensors). These nerve cells send messages to the brain, which in turn causes the pituitary gland at the base of the brain to release the hormone oxytocin into the bloodstream. Oxytocin causes stronger contractions of the smooth muscles in of the uterus (the effectors), pushing the baby further down the birth canal. This causes even greater stretching of the cervix. The cycle of stretching, oxytocin release, and increasingly more forceful contractions stops only when the baby is born. At this point, the stretching of the cervix halts, stopping the release of oxytocin.

A second example of positive feedback centers on reversing extreme damage to the body. Following a penetrating wound, the most immediate threat is excessive blood loss. Less blood circulating means reduced blood pressure and reduced perfusion (penetration of blood) to the brain and other vital organs. If perfusion is severely reduced, vital organs will shut down and the person will die. The body responds to this potential catastrophe by releasing substances in the injured blood vessel wall that begin the process of blood clotting. As each step of clotting occurs, it stimulates the release of more clotting substances. This accelerates the processes of clotting and sealing off the damaged area. Clotting is contained in a local area based on the tightly controlled availability of clotting proteins. This is an adaptive, life-saving cascade of events.

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Access for free at https://openstax.org/books/anatomy-and-physiology/pages/1-introduction

• Authors: J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix
• Publisher/website: OpenStax
• Book title: Anatomy and Physiology
• Publication date: Apr 25, 2013
• Location: Houston, Texas
• Book URL: https://openstax.org/books/anatomy-and-physiology/pages/1-introduction
• Section URL: https://openstax.org/books/anatomy-and-physiology/pages/1-5-homeostasis

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