Biology Exercise

Exercise 1 (20 marks)
1. What happens to the blood pressure and heart rate when the arterial resistance is increased?

When arterial resistance is increased, the blood pressure increases and heart rate decreases. For instance, when arterial resistance increased to 150%, systolic blood pressure increases to 132.8mmHg, diastolic pressure increases to 82.1 mmHg, and heart rate decreased to 51.8/min.

2. What might give rise to condition with increased arterial resistance with a systolic blood pressure of more than 160 mmHg and or diastolic of 95 mmHg?

High blood pressure or hypertension is a common condition in which the force of the blood on the walls of the arteries is chronically elevated
Decreasing blood volume to 3 litres- blood loss due to accident

Exercise 4 (20 marks)
Compare and contrast the effect of blood loss between the two conditions tested (4000ml and 3500 ml) with a cardiac performance of 50%. How much more serious is severe blood loss in a person with only 50% cardiac performance?

When blood volume drops it is marked by low blood pressure, increased in heart rate and a decreased in cardiac output. For instance, a decreased in blood volume up to 4000ml leads to a decreased in blood pressure to 84.1/ 58.0 mmHg (normal blood pressure is 121/70 mmHg), an increased in heart rate to 114.5 bpm and decreased in cardiac output to 3.1l/min.
Blood loss at 3500ml results in further decreased in blood pressure at 53.8/37.2 mmHg, further increased in heart rate at 115.6 bpm and decreased in cardiac output at 2.0l/min.
When systolic blood pressure drops below 90mmHg the body is in acute circulatory crisis and critical stage because the brain and vital organs become starved with nutrients and oxygen due to inadequate peripheral blood flow and low blood pressure leading to decreased cardiac output. This stage needs immediate intervention to prevent further complication and to restore blood
What is happening in the case of severe haemorrhage?

In class I haemorrhage, the total blood loss volume could be up to 15% with a minimal physiological change. For instance, blood pressure was recorded at 102.1/68.9mmHg, cardiac output at 4.1 l/min, and heart rate at 104.7 bpm, after 3 minutes, there is no change in vital signs at this stage. Patient may experience mild anxiety but the body can recompense well for this degree of haemorrhage without any fluid resuscitation.

Class II haemorrhage is between 15-30% of blood loss. The patient’s blood pressure decreased to 85.5/59.8mmHg and heart rate increased from to 134.8bpm. Such blood loss caused a decrease in cardiac output to 3.3 l/min. Body attempts to compensate by mobilizing venous reserve through venoconstriction to improve cardiac output and restore normal arterial pressure (Martini and Bartholomew, 2010).

In class III haemorrhage blood volume decreases up to 30-40% and patients is often experiencing rapid heart beat between 129.9bpm to 111.7 bpm. Low blood pressure (52.1/36.3 mmHg) lead to decrease in cardiac output to 2.0 l/min and further declined after minute’s