Lab 11: The Circulatory System – Student Name

Lab 11 The Circulatory Systembio202lstudent Nameclick Here To Enter

Describe the pathway of blood traveling through the closed system of the circulatory system starting with the right atrium. What are the main resistance vessels of the circulatory system? How are they controlled?

Label each of the items in the following slide pictures based on your observations. What differences did you observe in the structure of an artery versus the structure of a vein? Explain the direction of blood flow and the type of blood (oxygenated or deoxygenated) found in each vessel in the pulmonary and systemic circuits. Which vessels allow diffusion of oxygen and nutrients across their cell layers? List the vessels in order of ascending pressure within the circulatory system.

Insert screenshot of the descending aorta:

Insert screenshot of the brachial veins:

Insert screenshot of the femoral artery:

In what body region does the aorta originate? What organ does the renal artery supply? What branch of the external carotid artery supplies the chin/jaw region with blood? Is the common iliac artery anterior or posterior to the common iliac vein? What is the name of the artery in the pelvic region that directly feeds into the femoral artery?

Blood Pressure Table 2: Blood Pressure and Pulse Readings Activity Blood Pressure (Systolic/Diastolic; mmHg) Pulse (beats/minute) Basal (Normal) Click here to enter text. Click here to enter text. Lying Down Click here to enter text. Click here to enter text. After Exercise Click here to enter text. Click here to enter text.

What is systolic pressure? What is diastolic pressure? Why is pressure a sensible reading to measure circulatory health? Explain the “lub-dub” sounds of the heartbeat. Why do blood pressure and heart rate change after exercise? How might the results in Table 2 change if someone else performed the activities? Why is it important for blood to flow in only one direction?

What is the process that is responsible for moving molecules from an area of high concentration to an area of low concentration? In what part of the circulatory system does this happen? What observations did you make about the fetal pig’s circulatory system? Insert photo of your pig’s exposed heart, aorta, and jugular vein with your name and access code handwritten clearly in the background: “

Paper For Above instruction

The circulatory system is a complex and vital network responsible for transporting blood, nutrients, gases, and waste products throughout the body. Understanding its pathways, structures, and functions is key to comprehending human physiology and addressing circulatory health issues. This essay explores the blood flow pathway through the heart, the nature of resistance vessels, structural differences between arteries and veins, blood flow direction and oxygenation, diffusion across vessel walls, and the pressure hierarchy within the system. Additionally, it discusses the preparation of virtual models and dissection observations to provide a comprehensive overview of the circulatory system's integral functions.

The Pathway of Blood Through the Circulatory System

Blood flow begins in the right atrium of the heart, which receives deoxygenated blood from the superior and inferior vena cavae. From the right atrium, blood moves through the tricuspid valve into the right ventricle. During ventricular contraction, blood is propelled through the pulmonary valve into the pulmonary arteries, leading to the lungs for oxygenation. Oxygenated blood then returns via the pulmonary veins to the left atrium, passes through the mitral valve into the left ventricle, and is finally pumped through the aortic valve into the ascending aorta. From here, blood is distributed to systemic arteries that deliver oxygen-rich blood to tissues throughout the body. After passing through capillaries, where exchange occurs, deoxygenated blood returns via veins to the right atrium, completing the cycle.

Resistance Vessels and Their Control

Main resistance vessels include arterioles and small arteries, which regulate blood flow and pressure. These vessels are controlled primarily by autonomic nervous system signals, which cause vasoconstriction or vasodilation. Local factors, such as oxygen levels, carbon dioxide, and metabolic waste, also influence vessel diameter. This regulation ensures tissues receive adequate blood supply based on metabolic demand and maintains systemic blood pressure within optimal ranges.

Structural Differences Between Arteries and Veins

Arteries possess a thicker tunica media with more elastic fibers compared to veins, enabling them to withstand higher pressures from the heart's contractions. Veins, conversely, have thinner walls and often contain valves to prevent backflow, accommodating lower pressure blood return to the heart. Microscopically, arteries exhibit a rounder lumen and more elastic tissue, whereas veins have a wider lumen and less elastic tissue.

Blood Flow and Oxygenation in Pulmonary and Systemic Circuits

Oxygen and nutrients diffuse across the thin walls of capillaries, which are specialized for exchange due to their minimal wall thickness and large surface area. These vessels are critical exchange sites where oxygen enters tissues and carbon dioxide and waste products are removed.

Order of Vessels Based on Pressure

1. Heartbeat generates the highest pressure in the aorta.
2. Large arteries maintain high pressure but less than the aorta.
3. Arterioles control intermediate pressure, being site-specific regulators.
4. Capillaries operate under lower pressure conducive to exchange.
5. Venules and veins carry blood under minimal pressure back to the heart.

Virtual Model and Anatomical Insights

The virtual models of the descending aorta, brachial veins, and femoral artery demonstrate the complexity and specialization of vessel structures in different regions. The aorta originates in the thoracic cavity, supplying the entire body. The renal artery, branching from the abdominal aorta, supplies the kidneys, vital for filtration. Branches of the external carotid artery, such as the facial artery, supply the chin and jaw region. The common iliac artery, located anterior to the iliac vein, supplies the pelvic and lower limb regions, with the femoral artery as a major downstream vessel in the thigh.

Blood Pressure and Heart Rate Dynamics

Systolic pressure refers to the peak pressure during ventricular contraction, while diastolic pressure is the minimum pressure during relaxation. These metrics provide essential insights into vascular health, with abnormal values indicating potential issues such as hypertension or hypotension. The characteristic “lub-dub” sounds are caused by the closing of heart valves—tricuspid and mitral (lub), and pulmonary and aortic (dub). Post-exercise increases in blood pressure and heart rate occur due to sympathetic nervous system activation to meet increased metabolic demands. Variations among individuals depend on fitness, age, and health status.

Circulatory Exchange and Fetal Pig Observations

The movement of molecules from areas of high to low concentration occurs primarily via diffusion, a passive process central to exchange at capillary beds and cellular membranes. Dissection of the fetal pig revealed the intricate pathway of blood, including the direct connections between the heart, major arteries, and veins. Observations included the structural features like the thin-walled chambers and large elastic arteries supporting efficient blood flow. The pig’s circulatory system offers valuable insights into comparative anatomy, illustrating both conserved and unique features of mammalian circulation.

Conclusion

The circulatory system's architecture ensures efficient delivery of oxygen and nutrients while removing waste. Its regulation and structural adaptations are vital for maintaining homeostasis. Understanding the pathways, vessel types, and their functions allows for better comprehension of cardiovascular health and disease states. From the microscopic structure of vessels to the systemic pressures, every component plays a crucial role in sustaining life.

References

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