CV, Immunology, Respiratory, & Gastrointestinal - Questions

Cardiovascular

Questions 

1. List the chambers and valves of the heart that blood must pass through when traveling from the superior/inferior vena cava to the aorta. Which valves are fitted with cordae tendineae and why? What effect would damage to the papillary muscle in the left ventricle have on blood flow through the left side of the heart?

2. A baby at 10 days of age presents with tachypnea. A chest X-ray reveals wet lungs with increased pulmonary vascular flow. In addition, a physician notes that the baby’s legs seem cool to the touch and have a “mottled” appearance. List the bypasses/shunts that normally close at birth and describe their function in the fetal circulation. Which of these is likely responsible for the baby’s difficulties at 10 days of age and why? Please be sure to describe how the presence of the shunt/bypass after birth would contribute to each of the signs indicated above.

3. During development, the heart transitions from a tubular structure to that of a four chambered pump. One of the tubular structures known as the truncus arteriosus will eventually give rise to the two great vessels of the heart (and their associated valves). Describe how division of the truncus arteriosus occurs. Which structures are formed by division of the truncus arteriosus? Describe two congenital heart defects that may arise when the truncus arteriosus does not develop properly. What are the consequences to blood flow and the well-being of the neonate if these defects are present at birth?

4. In a heart attack, cardiac tissue often dies, and the electrical conduction system within the heart is interrupted. Describe the components of the cardiac conduction system and explain how this system accomplishes its task of coordinating atrial and ventricular contractions to ensure that the heart pumps blood in an efficient manner. In doing so, please describe the importance of the various phases of the electrocardiogram 
(ECG/EKG).

5. Stroke volume is influenced by three main factors – one factor is preload. What is preload and how does it influence stroke volume? What is the Frank-Starling Law of the heart and how does it relate to preload? What factors affect preload? (provide examples of factors that both increase and decrease preload)

6. You have managed to sleep through your alarm clock again. Unfortunately, today is no ordinary day… you have an exam to write in less than 20-minutes! As the gravity of the situation registers with your waking cortex you suddenly leap out of bed! As you stand there frantically planning your next move, you realize that your heart is racing. Describe the cardiovascular reflex that is responsible for ensuring that adequate blood flow (pressure) reaches your brain as you make the change from a supine to a standing position. In doing so, indicate which structures serve as detector (sensor), control center, and effector in this feedback loop. Which cardiovascular parameters are altered by this feedback loop (and in what direction [increase / decrease]) to help ensure that BP - and hence blood flow to the brain – is maintained?

7. With age, atherosclerotic plaques can build up within the walls of major arteries. This may occasionally lead to stenosis (narrowing) of the renal arteries, reducing blood flow to the kidneys. How would stenosis of the renal arteries effect blood pressure in the rest of the body and why? Discuss the homeostatic mechanism involved, indicating where feedback occurs (hint: focus on the BP-regulation pathway(s) initiated by the kidneys). 

8. Mrs. Luckless is bleeding profusely following a car accident and is transported to the ER. She has a rapid pulse and despite the blood loss, her BP is somewhat normal. Describe the compensatory mechanisms (short-term & long-term) that are employed by the body to help maintain blood pressure despite the blood loss. 

9. Dr. Apgar, a university professor from Hamilton, is in the Swiss Alps studying astronomy during a sabbatical leave. He has been there for two days and plans to stay the entire year. During his first few days, Dr. Apgar notices that he quickly becomes breathless when walking up stairs and tires easily with any physical activity. His symptoms gradually disappear, and after two months he feels fine. Upon returning to Canada, Dr. 
Apgar has a complete physical exam and is told that his erythrocyte count (hematocrit) is higher than normal. Explain these findings. Will his RBC levels eventually return to normal? Why or why not?

10. Hemostasis is a quick and localized sequence (cascade) of events that helps to prevent a hemorrhage from occurring when a blood vessel is damaged. Hemostasis involves amongst other things – the formation of a platelet plug. Describe the three steps involved in the formation of a platelet plug. What complication may arise if a platelet plug (thrombus) were to detach and travel through the circulatory system? How does 
Aspirin help prevent a thrombus from occurring?

11. As a prophylactic measure, all health care workers at the McMaster Health Sciences Centre are routinely given an annual flu shot. Explain how the influenza vaccine prevents severe illness from the flu. Discuss in terms of primary and secondary humoral immune responses. Explain at least three ways in which antibodies help protect us from pathogens.

12. Briar Rose pricks her finger on a nasty - and rather dirty looking - wooden spindle, receiving a painful splinter. She decides to ignore the splinter and wraps a bandage around her finger. The next day, Briar Rose had red streaks running up her right arm and they feel warm to the touch. A few days later she notices tender swollen bumps in her right armpit. What happened to her arm and armpit? Describe in terms of innate and adaptive immune mechanisms. Note: this is not the first time she has pricked her finger!

13. During a fantastic sword fight, Inigo Montolia stabs Count Rugen in the ribs with such a vengeance that Count Rugen suffers a pneumothorax. What is a pneumothorax? What forces are responsible for creating the negative intrapleural pressure that normally prevents the lungs from collapsing? Describe how these forces change throughout a normal quiet breathing cycle. How does intrapleural pressure change throughout the breathing cycle and how does this relate to intrapulmonary pressure? (Draw a graph to illustrate this)

14. COPD is an example of a disease where ventilation-perfusion mismatch occurs. What is ventilation-perfusion matching? How do the lungs attempt to maintain a proper ventilation-to-perfusion ratio? (describe the mechanism) In COPD, very few airways are well ventilated. Describe what effects this might have on total pulmonary vascular resistance, right ventricular pressures, and systemic vascular return. What will likely 
happen to PaCO2 levels over time and why?

15. During a severe bout of pneumonia, Eduardo had difficulties breathing. His PaCO2 was elevated and he became acidotic. Describe how CO2 travels from the tissues to the lungs to be expelled from the body. In doing so, describe the various forms that CO2 takes along the way. Finally, describe how CO2 levels affect blood pH.

16. What effect does hyperventilation have on blood pH and why? What simple measure can be used to correct this pH imbalance and how does it work? What effect would this pH imbalance have on the hemoglobin O2 saturation curve? What are some signs and symptoms caused by hyperventilation?

17. Mastication (chewing) is a concerted effort between the teeth, cheeks and tongue. Describe the structure and function of the intrinsic and extrinsic muscles of the tongue. What is their innervation? Which muscle allows you to stick out your tongue? Describe the tongue’s role in early deglutition.

18. The parietal cells of the stomach are responsible for producing hydrochloric acid which amongst other things helps to denature and breakdown ingested proteins. Describe how this acid is formed (i.e. what are the sources of H+ and Cl-?) How is the stomach protected from its own acidic contents? What effect might chronic vomiting have on blood pH and why? Finally, describe the function of the other major cell types found within the gastric pits. 

19. Describe the three phases of digestion. Please be sure to describe the hormonal and neural inputs that regulate gastric activity during each phase. How does the composition of chyme entering the duodenum control the rate of gastric emptying? Why does eating a meal rich in fats make you feel full (satiated) very quickly?