Answers to mcgraw hill connect anatomy

1. Use Figure 19.9 in the text to follow the flow of blood through the heart.

a. The heart consists of four chambers. The two chambers at the top are the Atria and the two chambers at the bottom are the Ventricles Blood returns to the heart from the rest of the body through two major veins ( _________________________________) and enters the __________________ of the heart. The blood then flows through the right AV valve to the right ventricle. (The purpose of this chamber is to pump blood through a second valve (Mitral valve) into the left ventricle . This large artery divides into the ____________________________________, which transports the blood to the ____________ for gas exchange.

b. Blood returns from the lungs via the ________________________ and enters the ___________ of the heart. The blood then passes through the ____________ to the____________________. (The purpose of this chamber is to pump blood through a fourth valve (___________ valve) to the largest artery called the ____________________________.) Blood flows from this artery to the every organ in the body where _____ is unloaded and _____ is picked up. The blood then returns to the _____________________ via the superior and inferior ___________________.

2. What is the coronary circulation?

3. What are the three main branches of the left coronary artery (LCA)? Where are they located on the heart surface (e.g. what part of the heart do they service)?

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4. What are the two main branches of the right coronary artery (RCA)? Where are they located on the heart surface?

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5. (a) What is a myocardial infarction? (b) What is its cause?

6. What is the medical significance of anastomoses in the coronary arterial system?

7. When do the coronary arteries obtain the greatest amount of blood to supply the heart: during heart contraction or heart relaxation? ___________________________________

8. (a) What are the three major coronary veins that empty into the coronary sinus? (b) Where does the coronary sinus empty the blood?

Section 19.3

9. Describe the structure of a cardiomyocyte. (A drawing might be helpful.)

10. The sarcoplasmic reticulum of cardiomyocytes are less developed than that of myofibers (skeletal muscle cells) and lacks terminal cisternae. Explain why. (Hint: what is the purpose of these structures? See section 11.2)

11. (a) What exactly is an intercalated disc? (b) What is the purpose of its electrical junctions?

12. Compare the size of the mitochondrion of a cardiomyocyte to that of skeletal muscle fibers. What does this difference signify?

13. Cardiac muscle rarely uses anaerobic fermentation to generate ATP. Why is this good a thing?

14. At rest, the heart gets 65% of its energy from _________________, 35% from ______________, and 5% from other fuels such as ketones, lactate, and amino acids.

15. (a) Where is the pacemaker of the heart located? (b) Describe the path of electrical conduction in the cardiac conduction system. (Hint: also see figure 19.12)

16. The heart can beat on its own. However, it also is innervated by both the parasympathetic and sympathetic system. Briefly explain the main way each of these regulate the heart.

Section 19.4

17. Define systole and diastole.

18. What is sinus rhythm, and what is the typical heat beat? How often does the SA node fire?

19. What is an ectopic focus? Give an example. Why is this of importance?

20. The SA node fires spontaneously at regular intervals because of the pacemaker potential. How does this potential differ from the resting membrane potential of a neuron or skeletal muscle?

21. Why is it important that the AV node slow down signal conduction to the ventricles?

22. Summarize the steps of an action potential of a ventricular cardiomyocyte. A drawing might be helpful (see figure 19.14).

23. (a) The resting membrane potential of a typical cardiomyocyte is __________.

(b) Which ions participate in the action potential of these cells? ____________________________

39. What produces the plateau in the action potentials of cardiomyocytes? Why is this important to the pumping ability of the heart?

24. Draw a normal electrocardiogram from just before P to just after T wave (see figure 19.15). Label the waves and intervals. Identify the portion of the ECG that coincides with each of the following events: atrial depolarization, ventricular depolarization, ventricular systole, ventricular repolarization, ventricular diastole.

Section 19.5

25. Differ between pressure and resistance.

26. What tool measures blood pressure? What are the units of measurement?

27. When ventricles are relaxed, what is the relative state of its pressure? What effect will it have on the AV valves and what will happen to blood flow?

28. When ventricles are contracted, how is its pressure affected? What effect will it have on the AV valves? What effect will it have on the semilunar valves? What will happen to blood flow?

29. What factors are thought to cause the first and second heart sounds? When do these sounds occur?

30. Phases of the cardiac cycle

a. Ventricular filling occurs during ________________ when the pressure of the _____________ is lower than the pressure of the ______________. The ventricles fill rapidly during the 1st third of this phase and slows down during the 2nd third. At the end of this point atrial contraction (_____________) occurs, which completes the filling of the ventricles. There is ____ mL of blood in each ventricle at the end of ventricular filling. This volume of blood is called the ______________________________________

b. During isovolumetric contraction, the _____________ repolarize, which results in its relaxation (_________________). The ventricles ____________________ and begins to contract. Pressure in the ventricles rises sharply causing the ________________ to close. However, the ________________________________ valves remain closed because the pressure in the pulmonary trunk and aorta exceeds that of the ventricles.

c. Ventricular ejection then follows when the rising pressure of the ______________ exceeds the ___________________ pressure of the pulmonary trunk and aorta. This lasts for roughly ____ to _____ ms. Note that all the blood is not expelled. Only _____ mL is expelled into the arteries; this is called the ______________ volume. This leaves _____ mL in each ventricle, which is called the _______________________________.

d. The last phase, isovolumetric relaxation, occurs during ventricular ______________. At the beginning of the period blood from the pulmonary trunk and aorta flows backward causing the _______________________ to close. The _______________ are also still closed during this period. Once the _______________ opens, step 1 (ventricular filling) begins again.

31. What is the overall function of leukocytes?

32. Fill in the following chart about volume changes:

Begins with……………

End-systolic volume (ESV)…..

_________

Atrial diastole (1st 1/3)...

Passive addition………………

_________

Atrial systole (last 1/3)...

Active addition……………….

_________

Total…………………...

End-diastolic volume…………

_________

Ventricular systole…….

Stroke volume………………..

_________

Left with……………….

End-systolic volume………….

_________

Sections 19.6

33. Define cardiac output in words and with a simple mathematical formula.

34. (a) Describe the cardiac center and the two main types of neurons. (b) What are the contributions of the sympathetic and parasympathetic divisions?

35. How do preload, contractility, and afterload influence stroke volume and cardiac output?

36. Where are cardiac baroreceptors located? What is the function of these receptors?

37. Where are cardiac chemoreceptors located? What is the function of these receptors?

38. What does the Frank-Starling law of the heart states? Why is this of importance?

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