Podcast
Questions and Answers
What is the hematocrit in a person with a plasma volume of 3 L and total blood volume of 4.5 L?
What is the hematocrit in a person with a plasma volume of 3 L and total blood volume of 4.5 L?
Which component of the circulatory system is primarily responsible for the rapid flow of blood?
Which component of the circulatory system is primarily responsible for the rapid flow of blood?
Which layer forms between erythrocytes and plasma when blood is centrifuged?
Which layer forms between erythrocytes and plasma when blood is centrifuged?
What role do baroreceptors play in the cardiovascular system?
What role do baroreceptors play in the cardiovascular system?
Signup and view all the answers
What happens to erythrocytes during the process of measuring hematocrit?
What happens to erythrocytes during the process of measuring hematocrit?
Signup and view all the answers
Which of the following refers to the mechanical events during the cardiac cycle?
Which of the following refers to the mechanical events during the cardiac cycle?
Signup and view all the answers
What primarily determines the physical function of the circulatory system?
What primarily determines the physical function of the circulatory system?
Signup and view all the answers
Which of the following components is NOT part of the vascular system?
Which of the following components is NOT part of the vascular system?
Signup and view all the answers
What contributes to the automaticity of the SA node?
What contributes to the automaticity of the SA node?
Signup and view all the answers
What effect does a drug that reduces L-type Ca2+ current have on the ECG?
What effect does a drug that reduces L-type Ca2+ current have on the ECG?
Signup and view all the answers
Why is the ECG limited in diagnosing certain heart conditions?
Why is the ECG limited in diagnosing certain heart conditions?
Signup and view all the answers
How do the currents during the plateau of the action potential in cardiac cells compare?
How do the currents during the plateau of the action potential in cardiac cells compare?
Signup and view all the answers
What is one of the key differences between action potentials of cardiac muscle cells and nodal cells?
What is one of the key differences between action potentials of cardiac muscle cells and nodal cells?
Signup and view all the answers
What component of the ECG reflects the electrical activity of the heart?
What component of the ECG reflects the electrical activity of the heart?
Signup and view all the answers
Which ion channels contribute to the pacemaker potential of the SA node?
Which ion channels contribute to the pacemaker potential of the SA node?
Signup and view all the answers
What is primarily used to evaluate electrical events within the heart?
What is primarily used to evaluate electrical events within the heart?
Signup and view all the answers
What is the primary role of the conducting system of the heart?
What is the primary role of the conducting system of the heart?
Signup and view all the answers
Which of the following best describes the cardiac muscle cells?
Which of the following best describes the cardiac muscle cells?
Signup and view all the answers
What is the main blood supply to the myocardial cells?
What is the main blood supply to the myocardial cells?
Signup and view all the answers
What must happen to blood from the systemic veins before it is pumped back to peripheral organs and tissues?
What must happen to blood from the systemic veins before it is pumped back to peripheral organs and tissues?
Signup and view all the answers
What is the function of the coronary sinus in the heart?
What is the function of the coronary sinus in the heart?
Signup and view all the answers
How does the cardiomyocyte structure support its function?
How does the cardiomyocyte structure support its function?
Signup and view all the answers
What advantage does the parallel branching of systemic arteries provide?
What advantage does the parallel branching of systemic arteries provide?
Signup and view all the answers
What does hemodynamics refer to in the context of the circulatory system?
What does hemodynamics refer to in the context of the circulatory system?
Signup and view all the answers
Which nerves supply autonomic innervation to the heart?
Which nerves supply autonomic innervation to the heart?
Signup and view all the answers
In the cardiovascular system, what primarily causes blood flow from one region to another?
In the cardiovascular system, what primarily causes blood flow from one region to another?
Signup and view all the answers
What occurs during the contraction of the atria in the heart?
What occurs during the contraction of the atria in the heart?
Signup and view all the answers
What occurs after blood is pumped from the left ventricle to peripheral organs at rest?
What occurs after blood is pumped from the left ventricle to peripheral organs at rest?
Signup and view all the answers
Why is it significant that approximately 1% of cardiac cells do not contract?
Why is it significant that approximately 1% of cardiac cells do not contract?
Signup and view all the answers
Which statement about hydrostatic pressure is correct?
Which statement about hydrostatic pressure is correct?
Signup and view all the answers
What is typically observed in the distribution of blood pumped by the left ventricle in an adult at rest?
What is typically observed in the distribution of blood pumped by the left ventricle in an adult at rest?
Signup and view all the answers
What happens to blood flow to different areas after a person eats a large meal?
What happens to blood flow to different areas after a person eats a large meal?
Signup and view all the answers
What initiates the early diastole phase of the cardiac cycle?
What initiates the early diastole phase of the cardiac cycle?
Signup and view all the answers
What is the typical pulmonary arterial diastolic pressure?
What is the typical pulmonary arterial diastolic pressure?
Signup and view all the answers
Which factor directly affects the calculation of cardiac output?
Which factor directly affects the calculation of cardiac output?
Signup and view all the answers
How does stroke volume typically change after significant blood loss?
How does stroke volume typically change after significant blood loss?
Signup and view all the answers
Which of the following heart sounds is not typically associated with normal cardiac contraction?
Which of the following heart sounds is not typically associated with normal cardiac contraction?
Signup and view all the answers
What primarily influences the timing and location of a heart murmur?
What primarily influences the timing and location of a heart murmur?
Signup and view all the answers
What is defined as the volume of blood each ventricle pumps per minute?
What is defined as the volume of blood each ventricle pumps per minute?
Signup and view all the answers
Which statement about pulmonary and systemic circulation pressures is accurate?
Which statement about pulmonary and systemic circulation pressures is accurate?
Signup and view all the answers
What vessel type is primarily responsible for offering significant resistance to blood flow?
What vessel type is primarily responsible for offering significant resistance to blood flow?
Signup and view all the answers
Which condition describes the phenomenon where blood flow increases due to heightened metabolic activity in tissues?
Which condition describes the phenomenon where blood flow increases due to heightened metabolic activity in tissues?
Signup and view all the answers
What is the approximate mean pressure in the blood as it flows through the arterioles?
What is the approximate mean pressure in the blood as it flows through the arterioles?
Signup and view all the answers
In the given equation, what is the simplified form for blood flow through an organ if venous pressure is close to zero?
In the given equation, what is the simplified form for blood flow through an organ if venous pressure is close to zero?
Signup and view all the answers
Which of the following factors is NOT mentioned as increasing with elevated metabolic activity?
Which of the following factors is NOT mentioned as increasing with elevated metabolic activity?
Signup and view all the answers
Which substance is generated locally and promotes vasodilation in response to metabolic activity?
Which substance is generated locally and promotes vasodilation in response to metabolic activity?
Signup and view all the answers
Which is an example of local control that allows organs and tissues to self-regulate their arteriolar resistance?
Which is an example of local control that allows organs and tissues to self-regulate their arteriolar resistance?
Signup and view all the answers
Which of the following is NOT a breakdown product of metabolism mentioned in the content?
Which of the following is NOT a breakdown product of metabolism mentioned in the content?
Signup and view all the answers
Study Notes
Systems Physiology
- This is a course on systems physiology
- The course outline includes:
- Cardiovascular physiology
- Respiratory physiology
- Kidney function and water/inorganic regulation
- Digestion and absorption of food
- Regulation of organic metabolism and energy balance
- Endocrine system
- Reproduction
- Medical physiology: Integration
Cardiovascular System Overview
- The circulatory system is a closed loop
- Blood is composed of formed elements (cells and cell fragments) suspended in plasma
- Hematocrit is the percentage of blood volume that is erythrocytes
- It's measured by centrifuging a blood sample
- The plasma remains on top and the leukocytes and platelets form a thin layer called the buffy coat
- Blood flow throughout the body is generated by the pumping action of the heart
- Most cells are within a few cell diameters of a capillary
- Nutrients and waste products move between capillary blood and the interstitial fluid via diffusion
- Only about 5% of the total circulating blood is in the capillaries at any given moment
- Capillaries are responsible for supplying nutrients and removing waste products
- The circulatory system is composed of two circuits: pulmonary and systemic
- The heart is divided into two halves (right and left) with two chambers each (atrium and ventricle)
- There is usually no direct blood flow between the atria or the ventricles
- The heart receives blood via the vena cava and pumps it through the aorta
Heart Anatomy
- The heart is a muscular organ enclosed in a pericardium
- The myocardium is primarily composed of cardiac muscle cells
- Endothelial cells line the inner chambers and blood vessels
- The heart is divided into right and left halves
- Each half consists of an atrium and a ventricle
- Atrioventricular (AV) valves allow blood to flow from atrium to ventricle (and not backward)
- The right AV valve is the tricuspid valve
- The left AV valve is the bicuspid (or mitral) valve
- The openings of each ventricle into the pulmonary trunk and aorta contain valves (pulmonary and aortic valves)
- There are no valves at the entrances of the superior and inferior venae cavae into the right atrium, and at the entrances of the pulmonary veins into the left atrium
- The heart receives autonomic innervation (sympathetic and parasympathetic)
- The heart has a rich blood supply via coronary arteries
Cardiac Muscle
- Cardiac muscle is electrically excitable and similar to smooth and skeletal muscles
- Action potentials propagate along cell membranes, Ca2+ enters the cytosol, and force-generating cross-bridges are activated
- Approximately 1% of cardiac cells do not contract (conducting system)
- The conducting system is composed of specialized cells that initiate and spread action potentials
Heart Beat Coordination
- The sinoatrial (SA) node is the normal pacemaker of the heart
- Electrical excitation of the heart is coupled with contraction
- The SA node's discharge rate determines the heart rate
- Depolarization through gap junctions spreads through the atria, and then the ventricles via the conducting system
- The conducting system (modified cardiac cells) conducts action potentials with a low resistance
The Electrocardiogram (ECG)
- Records the electrical activity of the heart
- Action potentials in many myocardial cells simultaneously generate currents detectable at the surface of the skin
- An idealized normal ECG is represented by waves on a graph
- Abnormal heart functions alter the shapes and timing of the waves
Excitation-Contraction Coupling
- Cardiac muscle action potentials to contraction are detailed in muscle physiology
- A single action potential releases sufficient Ca²⁺ to saturate the troponin sites, activating contraction
- The main mechanism for preventing summation is inactivation of Na⁺ channels
Mechanical Events of Cardiac Cycle
- Atrial and ventricular contractions and relaxations occur in a recurring cardiac cycle
- There is a period with all valves closed during isovolumetric ventricular contraction and relaxation
- The AV valves open during ventricular filling as blood flows into the ventricles
- Atrial contraction occurs near the end of diastole, filling ventricles
- Ventricular ejection empties most of the ventricles before contraction
- The pressure changes in the heart and the related movements are shown in graph form
Pulmonary Circulation
- The pressure changes in the right ventricle and pulmonary arteries are similar to those in the left ventricle and aorta
- The pressures are lower in the pulmonary circuit
- The pressures (pulmonary and systemic) are very different in magnitude
Heart Sounds
- Two heart sounds result from cardiac contraction
- Murmurs are caused by turbulent blood flow
The Cardiac Output
- Cardiac output (CO) is the volume of blood each ventricle pumps per minute
- It is calculated as heart rate (HR) x stroke volume (SV)
- Factors that influence heart rate and stroke volume are included
Control of Stroke Volume
- The strength of ventricular contraction influence stroke volume
- Stroke volume increases with end-diastolic volume ("Frank-Starling" mechanism)
- Factors that alter stroke volume (end-diastolic volume, sympathetic nervous system input, and afterload) are identified
Control of Heart Rate
- The heart's inherent autonomous discharge rate is approximately 100 beats per minute (controlled by the SA node)
- Sympathetic and parasympathetic activity to the SA node influence beating rate
- When sympathetic activity dominates, the heart rate increases; Conversely, parasympathetic activity decreases heart rate
Measurement of Cardiac Function
- Human cardiac output and function are measured by various techniques, including echocardiography and cardiac angiography
The Vascular System: Arteries
- Arteries are the vessels that carry blood away from the heart
- Arterial blood pressure has a specific pattern
- Factors affecting pulse pressure (stroke volume, ejection speed, artery compliance) are enumerated
The Vascular System: Arterioles
- Arterioles are the major factor affecting mean arterial pressure, and they control the distribution of blood within organs.
- Several autoregulating mechanisms for local control of arteriole resistance are considered: Active hyperemia, flow autoregulation, and reactive hyperemia
- Extrinsic controls (sympathetic neurons) on arteriolar smooth muscles and hormones (epinephrine, angiotensin II) are elaborated
- This is a mechanism used in specific organs, such as the heart, skeletal muscle, lungs, and in the splanchnic organs
The Vascular System: Capillaries
- Capillaries are critical in tissue function for substance exchange
- The structure of capillaries enable rapid exchange across capillary walls: diffusion, vesicle transport, bulk flow, and mediated transport
- Blood flow characteristics of capillaries are given and compared to other blood vessels
The Vascular System: Veins
- Blood is returned to the heart through veins
- Venous pressure and venous return to the heart are determined by factors such as the activity of sympathetic nerves to veins, blood volume, and the skeletal muscle pump
- The venous pressure mechanism is explained via a diagram
The Vascular System: Lymphatic System
- The lymphatic system is a network of lymph nodes and lymphatic vessels that remove interstitial fluid and carry immune cells
- Lymph flow is propelled/regulated by lymphatic vessel smooth muscle contractions and sympathetic neuron innervation
Integration of Cardiovascular Function
- Mean systemic arterial pressure is determined by the product of cardiac output and total peripheral resistance
- Short-term mechanisms (reflexes) and long-term mechanisms (affecting blood volume) for regulating arterial pressure are discussed
- Also, other reflexes and responses involved in regulation of blood pressure are analyzed
- The medullary cardiovascular center in the medulla oblongata is the primary integration center
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on the cardiovascular system with this comprehensive quiz. Explore topics such as hematocrit, blood flow, and the cardiac cycle. Answer questions about the role of baroreceptors and cardiac action potentials to deepen your understanding of how the circulatory system operates.
