Heart and Blood Vessels

1. Complete the following scheme of blood circulation in human heart.                                         

Right atrium through the tricuspid valve to the right ventricle through the Pulmonary valve to the pulmonary trunk, to the semi lunar for oxygenation, to the pulmonary veins back into the left atrium of the heart, through  the  mitral valve into the left ventricle, through the left semi lunar valve into the arteries, that supplies systemic blood to the body and then deoxygenated blood goes back into the right atria via tricuspid valve, superior vena cava and inferior vena cava pulmonary artery.

2. The beating of human heart (cardiac cycle) directly reflects the electrical conduction system within the heart (ECG). Describe what happens in the cardiac cycle in the following situations:                                    

a. Immediately before P wave: Senatorial node fires causing the contraction of atria. Before this heart’s resting period no electrical activity is performed and muscles relax to fill the atria with blood.

b. During P wave: At the sinoatrial node the contraction of heart muscle starts. It last for 0.08 seconds. P wave slows down the process of depolarization at the end.

c. Immediately after P wave: The P-R segment occurs immediately the P wave occurs. This P-R segment is time travel to reach the ventricles from SA. After this the QR complex occurs.

d. During QRS wave: the depolarization wave movements is depicted through the QRS complex. It makes large upward spikes. The QRS complex shows the conduction depolarization waves synchronously.

e. During the T wave: It is the last readable wave in a cycle on ECG. Heart’s re-polarization is represented here. It means that ventricles have sent the blood to the body and heart goes to reset itself for the next cycle (Elaine 696).

3. Suppose a person has a heart rate of 70bpm and has a stroke volume (SV) of 70ml. A negative inotropic agent (any substance that reduces contractility of heart) reduces the SV to 50 ml. What would the new heart rate have to be to maintain the same cardiac output?

Heart rate: 70bpm

Stroke Volume SV: 70 ml

Cardiac output = HR x SV

                        = 70x70 =4900 ml/min

SV after reduction = 50 ml

Cardiac Output: heart rate x Stroke Volume

                        = 70 x 50, 3500 ml/min or 3.5 L/min

New Heart rate = Cardiac output/ Stroke Volume

                = 4900/50 = 98bpm                                                                                                         

4. A 55-year-old male was admitted to the hospital with heart failure.  He complains of increasing shortness of breath on exertion and needing to sleep on three pillows at night.  On physical assessment, the nurse determines that his ankles and feet are very swollen.  Which of these symptoms reflect left-sided heart failure and which reflect right-sided heart failure?                                                                                                   

Answer: The left sided heart failure occurs due to reduction in cardiac output of arterial blood. Other symptoms of left ventricular failure include as the hypoxia, crackles, cyanosis, fatigue, dyspnea, paroxysmal nocturnal, elevated pulmonary and capillary wedge pressure. Right side heart failure occurs due to weight gain. Dependent pitting edema is also observed in patient’s feet and ankles. This edema is disappeared overnight but spreads in other tissues. Other symptoms of right side heart failure include the weakness, jugular vein distension, vomiting, and nausea, elevated and central venous pressure (Barbara and Nancy 426).

Use the following hint to solve the problem:

-Think about the normal flow of blood within the heart

- Now think, what will happen if the left side of the heart is not pumping properly. Where will the blood pool up. Now try to think about the symptoms the patients may experience due to pooled up blood.

-Repeat all these steps for the right side of heart as well.

5. Becky, age 2, was born with a hole in her interventricular septum (ventricular septal defect or VSD). Considering that the blood pressure in the left ventricle is significantly higher than the blood pressure in the right ventricle, predict the effect of VSD on Becky’s                                                               10 points

a. pulmonary BP: The VSD creates the greater pressure on two ventricles, it is higher in left ventricles than right ventricles. The VSD allows the oxygenated blood to flow from the left ventricle to right ventricle. In right ventricle the pressure is low and mixed blood the flows to circulate into lungs. It is not apparent in infant at the time of birth because left ventricular and right ventricular pressures are equal. As the child grows the right ventricular pressure decreases and blood shunts from left ventricular to right ventricular. Becky will suffer from the occurrence of cyanosis and biventricular heart failure. Chest wall will become prominent and resulting into increased risk of pneumonia for Becky.

b. systemic blood pressure. Systemic blood pressure is disturbed due to effects of VSD in an infant like Becky. VSD is not closed in Becky so blood flows under higher pressure into arteries and arteries become thicker. Right ventricular works extra to control the high blood volume and lungs receive the extra blood pressure. Lungs are permanently damaged due to this blood pressure.

Explain why?

     6. Based upon the topic of blood pressure and the factors controlling blood pressure, for each of the given situations, describe the anticipated effect on blood pressure and the physiological basis (reasoning) of your response                                                                                                                                         

a. A high salt diet: kidneys are the organs to control the level of salts in our body. When intake level of salt is high then kidneys cannot control the level of salt and it ends up into blood stream. Salt requires more water into blood which results into increase volume of water. This increases the volume of blood and blood pressure is also raised. It is also noted that hypertrophy is linked with excessive amount of NaCl.

                  b. A blow on head that damages (disables) the vasomotor center: The process of vasoconstriction is controlled by the vasomotor center in brain. This process of vasoconstriction regulates the blood pressure. When this vasomotor centre is disabled them improper vasoconstriction may cause the increase in blood pressure and hypertension.

      c. Hypothalamic tumor resulting in excess ADH production: There are two causes behind it. Firstly, it makes the kidneys to retain more volume of water which increases the blood pressure. Secondly, it causes the blood vessels to squeeze down and causing the blood pressure to go up. Due to elevation of ADH, kidneys start to retain excessive volume of water resulting into expansion of plasma volume. This expansion in plasma volume causes the blood pressure to increase

    7. Edema (swelling due to increase in interstitial fluid) is a common clinical problem. On one of your first days of introductory clinical experience, you encounter three patients who all have severe edema for different reasons.  Your challenge is to explain the cause of edema. Note: In each case, try to explain the edema in terms of either an increase or decrease in one of the four pressures that cause bulk flow at capillaries (refer to slide # 76-80 of ppts.)

                  a. First, you encounter Mrs. Taylor in medical ward awaiting a liver transplant. What is the connection between liver failure and her edema? HINT: think about role of liver in producing plasma proteins.

Osmotic positional of plasma drops resulting into drop of plasma protein concentration. Capillaries absorb less fluid of interstitial. This condition of plasma protein reduction becomes the cause of edema. Liver failure also causes the decreased synthesis of plasma protein. The persons with liver failure have the impaired synthesis of albumin which causes decrease in colloidal osmotic pressure. Edema is also developed due to lack of amino acids required for the synthesis of plasma proteins (Carol 165).

      b. Next, you follow a resident to obstetric ward, where Mrs. So is experiencing premature labor. Which of the pressures that drive bulk flow might be altered here? HINT: What affect the expanding uterus might be having

A pregnant woman may feel the labor pains prematurely before 37 week of pregnancy because cervix opens before the time due to uterine contraction. Baby born may face the health problems, but medicine, new technology and research the baby becomes healthy. These women have the cervical abnormalities. There are other factors which cause the alteration in blood volume in pregnancy. Cardiac output also affects the normal delivery.

      c. Finally, you are called to emergency, where Mr. Herera is in anaphylactic shock. Which of the pressures that drive bulk flow might be altered here? HINT: In anaphylactic shock, the capillaries become highly leaky.

In anaphylactic shock the fluid buildup in the body tissues which results into an edema. This occurs due to high osmotic pressure in capillaries and low osmotic pressure in tissues. Blood has to reach the tissues but it diffuses back into capillaries. In anaphylactic shock blood from sides is prevented to enter the capillaries, tissues are swallowed and patient expires.

            The blood circulatory system has been discussed in this paper. A related numerical is also part of this paper.