The cardiovascular system continually adjusts where blood flows so active tissues receive oxygen and nutrients while waste products are carried away. This lesson introduces blood-flow allocation and the neural mechanisms that help regulate heart activity, vessel diameter, and blood pressure.
Blood flow is limited, so the body cannot supply every tissue with maximal flow at the same time. Instead, it redistributes blood according to current needs. During exercise, more blood is directed to skeletal muscles, the heart, and the skin; after a meal, more is directed to the gastrointestinal system. Blood flow to the brain remains relatively constant across rest and activity.
All flashcards
What is blood-flow allocation?
It is the continual redistribution of limited blood flow among tissues according to their current activity and metabolic needs.
What are the three functional components of the cardiovascular centers?
The cardioaccelerator centers increase cardiac activity, the cardioinhibitor centers decrease it, and the vasomotor centers regulate blood-vessel tone.
How do baroreceptors detect changes in blood pressure?
They sense stretch in vessel or heart walls. Greater stretch increases their firing rate; reduced stretch lowers their firing rate.
What is the atrial reflex?
It is a response to changes in venous return detected by receptors in the venae cavae and right atrium. Increased return can stimulate sympathetic activity and raise cardiac output.
What blood variables do chemoreceptors monitor?
They monitor oxygen, carbon dioxide, and hydrogen ion concentrations, thereby detecting changes related to blood pH and metabolic demand.
Quiz questions
In the local myogenic response, what happens when increased flow excessively stretches an arteriole?Answer: Its smooth muscle contracts, narrowing the vessel and limiting downstream flow.
What is one cardiovascular effect of atrial natriuretic hormone released when atrial walls are stretched?Answer: It promotes renal sodium and water loss while suppressing fluid-retaining signals.
During exercise, how can increased venous return raise stroke volume through the Frank-Starling principle?Answer: Greater preload stretches cardiac muscle, producing a stronger contraction.
Which condition characterizes cardiogenic shock?Answer: The heart cannot maintain adequate cardiac output to perfuse tissues.
How can regular aerobic training affect the resting heart rate needed to maintain a given cardiac output?Answer: A greater stroke volume can support that output with fewer beats.
Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.