BIOS 255 Week 2 Cardiovascular System: Heart
Student Name
Chamberlain University
BIOS-255: Anatomy & Physiology III with Lab
Prof. Name
Date
BIOS 255 Week 2 Cardiovascular System: Heart
Learning Outcomes
- Identify the chambers of the heart.
- Identify the location and function of the heart valves.
- Describe the pathway of blood flow through the heart.
- Define stroke volume and cardiac output.
- Explain how the cardiovascular system adapts to physical activity.
- Describe how cardiac output and blood pressure are measured.
Introduction
The heart is a powerful muscular organ responsible for pumping blood throughout the body via two primary circuits: the pulmonary and systemic circulations. It ensures that oxygen-poor blood is transported to the lungs for gas exchange and that oxygen-rich blood is distributed to meet the body’s metabolic needs. Made of specialized cardiac muscle tissue, the heart functions independently with its intrinsic rhythm, allowing it to continuously contract and pump blood.
Cardiovascular function must adjust to varying levels of activity. For instance, during physical exertion or cellular repair, tissues require increased oxygen and nutrients, which elevates the workload on the heart. Conversely, at rest, the heart functions at a reduced capacity. Cardiac output, defined as the volume of blood the heart pumps per minute, becomes a vital parameter to evaluate. This lab aims to understand how cardiac output, heart rate, and stroke volume respond to exercise and how these parameters can be measured accurately.
Part 1: Anatomy.TV Activities
To prepare for the virtual cardiovascular function lab, students must access and complete the Anatomy.TV modules on the cardiovascular system.
Navigation Path:
Resources tab → Library → Library Resources (Database A-Z) → Anatomy.TV → Titles (default tab) → Select Cardiovascular System → Choose Heart and Cardiac Output Sections
Once selected, scroll down the right side of the platform to view and complete all learning activities associated with the designated sections.
Part 2: Heart Lab Report
Purpose
The primary aim of this lab was to explore how the cardiovascular and respiratory systems adapt during exercise. It also focused on how to measure cardiac output (CO) and blood pressure (BP), and how heart rate (HR), stroke volume (SV), and total peripheral resistance change with activity.
Procedure
During the lab, we assessed cardiovascular responses to exercise using a Doppler ultrasound and a sphygmomanometer. Test subjects performed physical activity on a stationary cycle ergometer while we recorded measurements at rest and during incremental workload levels. Blood pressure (systolic/diastolic), heart rate, stroke volume, and cardiac output were obtained to evaluate cardiovascular function and potential abnormalities.
Data and Observations
| Parameter | HR at Rest | HR Max (Exercise) | SV at Rest | SV Max (Exercise) | CO at Rest | CO Max (Exercise) |
|---|---|---|---|---|---|---|
| Subject A | 60 bpm | 150 bpm @ 125 W | 70 ml/beat | 120 ml/beat | 4.2 L/min | 18.0 L/min |
| Subject E | 80 bpm | 200 bpm @ 75 W | 40 ml/beat | 35 ml/beat | 3.2 L/min | 7.0 L/min |
Questions
a. Describe the flow of blood, in order, starting at the superior vena cava, through the heart, to the lungs. Continue with the flow of blood from the lungs to and through the heart to the aorta. Include the 4 chambers of the heart, the 4 valves, and the major blood vessels entering or leaving the heart.
Blood enters the heart through the superior and inferior vena cava, flowing into the right atrium. It then passes through the tricuspid valve into the right ventricle. From there, it is pushed through the pulmonary valve into the pulmonary arteries, which carry it to the lungs for oxygenation. The oxygen-rich blood returns via the pulmonary veins into the left atrium, moves through the mitral (bicuspid) valve into the left ventricle, and finally exits through the aortic valve into the aorta, supplying the rest of the body.
b. Define stroke volume in words.
Stroke volume is the quantity of blood pumped out of a ventricle with each heartbeat.
c. Define cardiac output in words and with the equation.
Cardiac output refers to the total volume of blood the heart ejects per minute. It is calculated using the formula:
Cardiac Output (CO) = Stroke Volume (SV) × Heart Rate (HR)
d. How does an increase in heart rate affect cardiac output (assuming no change in stroke volume)?
If stroke volume remains unchanged, an increase in heart rate will proportionally increase cardiac output.
Discussion
a. Compare the change in heart rate, stroke volume, and cardiac output with exercise between Subject A and Subject E. What does this suggest regarding the health of the heart of Subject E?
Subject A showed significant increases in stroke volume and cardiac output with exercise, suggesting a healthy and efficient cardiovascular system. Subject E, however, experienced a decrease in stroke volume during exercise despite an elevated heart rate. This may suggest underlying cardiac dysfunction, possibly related to aortic valve regurgitation. The heart of Subject E is likely compensating for reduced output by increasing heart rate, which may also contribute to elevated systolic pressure and decreased diastolic pressure—an indicator of compromised cardiac efficiency.
b. Briefly mention any difficulties with the lab and/or information you wish was present in the lab.
The lab was conducted smoothly without any technical or procedural difficulties. However, it would be helpful to include comparative data from healthy and clinical populations for deeper analysis.
Reflection
1. Understanding Normal Cardiac Values
This lab enhanced my understanding of normal cardiovascular measurements. For example, a healthy heart rate (HR) typically ranges between 60–70 beats per minute, stroke volume (SV) is around 70 ml/beat, and cardiac output (CO) is approximately 5 liters per minute at rest.
2. Application of the Doppler Effect in Cardiology
I learned how Doppler ultrasound measures changes in frequency to assess blood flow and cardiac function. This principle is similar to how the pitch of a siren changes as an ambulance approaches and then moves away.
Grading Rubric for Lab Report Activity
| Activity | Points |
|---|---|
| Part 1: Complete Lab Activities/Simulation | 10 |
| Part 2: Complete Lab Report and Questions | |
| – Purpose | 2 |
| – Procedure | 2 |
| – Data and Details | 5 |
| – Questions | 4 |
| – Discussion | 2 |
| – Reflection | 5 |
| Total | 30 |
Abbreviations:
HR = Heart Rate
SV = Stroke Volume
CO = Cardiac Output
References
Hall, J. E., & Guyton, A. C. (2020). Guyton and Hall Textbook of Medical Physiology (14th ed.). Elsevier.
Marieb, E. N., & Hoehn, K. (2022). Human Anatomy & Physiology (12th ed.). Pearson.
BIOS 255 Week 2 Cardiovascular System: Heart
Widmaier, E. P., Raff, H., & Strang, K. T. (2019). Vander’s Human Physiology: The Mechanisms of Body Function (15th ed.). McGraw-Hill Education.