Identify the structures that direct circulation through the heart. Which structures have the thinnest walls? Why? - Answer The structures that direct circulation through the heart include the heart chambers (atria and ventricles) and the heart valves (tricuspid, bicuspid/mitral, pulmonary, and a...
NURS 2270 Midterm Exam 3 Questions
All Correct Answers Guaranteed Pass.
Identify the structures that direct circulation through the heart. Which structures have the thinnest
walls? Why? - Answer The structures that direct circulation through the heart include the heart
chambers (atria and ventricles) and the heart valves (tricuspid, bicuspid/mitral, pulmonary, and aortic
valves). The thinnest walls are found in the atria.
The atria have thinner walls compared to the ventricles because they primarily function to receive blood
from the veins (right atrium receives deoxygenated blood from the body, while left atrium receives
oxygenated blood from the lungs) and then pump it into the ventricles
Review and discuss blood flow during the cardiac cycle - Answer 1. Diastole: During diastole, the heart
is relaxed. The atria and ventricles are both in diastole, and blood flows passively from the veins into the
atria. As the atria fill with blood, they contract (atrial systole), further filling the ventricles. The AV valves
(tricuspid and mitral valves) are open during diastole, allowing blood to flow from the atria into the
ventricles. This phase accounts for about two-thirds of the cardiac cycle.
2. Systole: Systole is the contraction phase of the cardiac cycle. It is divided into two phases: atrial systole
and ventricular systole.
Atrial Systole: Atrial systole occurs as the atria contract, forcing any remaining blood into the ventricles.
This phase is relatively brief and completes the filling of the ventricles.
Ventricular Systole: Ventricular systole begins with the contraction of the ventricles. As the ventricles
contract, the pressure within them increases, closing the AV valves to prevent backflow of blood into the
atria. This phase is divided into isovolumetric contraction (initial phase when all valves are closed) and
ejection (blood is pumped out of the ventricles into the pulmonary artery and aorta). The semilunar
valves (pulmonary and aortic valves) open during ejection to allow blood to be ejected from the heart.
Describe how heart action (cardiac conduction) is stimulated and controlled. - Answer Heart action, or
cardiac conduction, is stimulated and controlled by a specialized electrical conduction system within the
heart. This system ensures that the heart chambers contract in a coordinated manner to pump blood
efficiently. The key components of the cardiac conduction system include:
1. Sinoatrial (SA) Node: Located in the right atrium, the SA node is known as the heart's natural
pacemaker. It generates electrical impulses spontaneously, causing the atria to contract. The electrical
impulse then travels through specialized pathways in the atria, leading to atrial contraction.
, 2. Atrioventricular (AV) Node: The AV node is located at the junction between the atria and ventricles. It
receives the electrical impulse from the SA node and delays its transmission slightly to allow the atria to
contract fully before the ventricles are stimulated.
3. Bundle of His: After passing through the AV node, the electrical impulse travels down the Bundle of
His, which is a bundle of specialized fibers that conducts the impulse from the atria to the ventricles.
4. Right and Left Bundle Branches: The Bundle of His divides into the right and left bundle branches,
which carry the electrical impulse to the respective right and left ventricles.
5. Purkinje Fibers:
Discuss the systemic circulation, including the structure of blood vessels, factors affecting blood flow, and
blood pressure regulation. - Answer Systemic circulation is the part of the cardiovascular system that
carries oxygenated blood from the heart to the body's tissues and returns deoxygenated blood back to
the heart. It includes a network of blood vessels that transport blood throughout the body.
-Arteries, Veins, and Capillaries
Relate the Frank-Starling law of the heart to the concept of preload. - Answer The Frank-Starling law of
the heart describes the relationship between the preload (the initial stretching of the heart muscle cells
before contraction) and the force of contraction of the heart. It states that the force of contraction of the
heart is directly proportional to the initial length of the muscle fibers, or in other words, the amount of
stretch experienced by the muscle fibers before contraction.
Describe the functions of baroreceptors and chemoreceptors. - Answer Baroreceptors detect changes
in blood pressure. When blood pressure increases, the walls of the blood vessels stretch, stimulating the
baroreceptors
Chemoreceptors detect changes in the levels of certain chemicals, such as oxygen, carbon dioxide, and
pH, in the blood and cerebrospinal fluid.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller COCOSOLUTIONS. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $9.99. You're not tied to anything after your purchase.
