QP Exam 3
describe the factors that influence MAP and flow
- Cardiac output: The amount of blood that is pumped by the heart each minute can affect MAP and flow. If the cardiac output is high, there will be more blood flowing through the arteries, which can increase MAP and flow. - Blood volume: The volume of blood in the circulatory system can also influence MAP and flow. An increase in blood volume can increase MAP and flow, while a decrease in blood volume can decrease MAP and flow. - Blood pressure: The pressure of the blood in the arteries can also affect MAP and flow. If the blood pressure is high, it can help push the blood through the arteries, increasing MAP and flow. - Arterial tone: The tone of the arteries, which is determined by the contraction of the smooth muscle in the walls of the arteries, can also affect MAP and flow. If the arteries are more relaxed, MAP and flow may be lower, while if the arteries are more contracted, MAP and flow may be higher. - Vasodilation and vasoconstriction: The widening or narrowing of the arteries, known as vasodilation and vasoconstriction, respectively, can also affect MAP and flow. Vasodilation, which is the widening of the arteries, can increase MAP and flow, while vasoconstriction, which is the narrowing of the arteries, can decrease MAP and flow.
. What are the factors that influence venous return?
-Blood volume: An increase in blood volume can increase venous return, while a decrease in blood volume can decrease venous return. -Cardiac output: The amount of blood that is pumped by the heart each minute can affect venous return. If the cardiac output is high, there will be more blood being pumped through the veins, which can increase venous return. -Blood pressure: The pressure of the blood in the veins can influence venous return. If the blood pressure is high, it can help push the blood back towards the heart, increasing venous return. -Venous tone: The tone of the veins, which is determined by the contraction of the smooth muscle in the walls of the veins, can also affect venous return. If the veins are more relaxed, venous return may be lower, while if the veins are more contracted, venous return may be higher. -Gravity: The position of the body can also affect venous return. For example, if a person is standing up, gravity can help pull the blood down towards the feet, increasing venous return. -Respiratory movements: The contraction and relaxation of the respiratory muscles during breathing can also affect venous return. During inspiration, the muscles contract and the chest expands, which can help increase venous return. -Physical activity: Engaging in physical activity can increase the flow of blood through the veins, which can increase venous return.
Five phases of the cardiac cycle
1. Atrial Systole: atrial contraction and ventricular filling; pressure is greater in the atrial and arterial trunk; AV valve opens, semilunar valves closed 2. Early Ventricular Systole: isovolumetric contraction; Atria relaxes, ventricles contract; pressure is greater in the atrial trunk than atria; both AV and semilunar valves are closed 3. Late Ventricular Systole: ventricular ejection;Atria relaxes, ventricles contract; both atrial and arterial trunk have low pressure; AV valve closed and semilunar valves open 4. Early Ventricular Diastole: isovolumetric relaxation; Atria and ventricles relax; pressure is greater in the arterial trunk tan atrial; Both AV valve and Semilunar valves are closed 5. Late Ventricular Diastole: atrial relaxation and ventricular filling; Atria and ventricles relaxes; atrial and arterial trunk both have high pressures; AV valve open, Semilunar valves closed
How does the AP relate to mechanical events occurring in the heart?
1. Reaching threshold: Na+ flows into the nodal cells, changing RMP from -60 mV to the threshold value of -40 mV *no outside stimulation required (see #3 below) 2. Depolarization: upon reaching threshold, Ca2+ flows into cell giving it a near positive RMP (0 mV) 3. Repolarization: Ca2+ channels close, K+ channels open allowing K+ out of cell è returns cell to RMP of -60 mV *this triggers the reopening of Na+ channels and process begins again (no outside activation needed)
Components of Conduction System
1.) Sinoatrial (SA) node: This small group of cells is located in the right atrium (one of the two upper chambers of the heart). The SA node is known as the "natural pacemaker" of the heart, as it generates spontaneous electrical impulses that initiate each heartbeat. 2.) Internodal pathway connects SA node to the AV node 2.) Atrioventricular (AV) node: This group of cells is located between the atria and the ventricles (the two lower chambers of the heart). The AV node receives the electrical impulse from the SA node and conducts it to the ventricles. 3.) Atrioventricular bundle (AV bundle): Also known as the Bundle of His, this group of fibers connects the AV node to the ventricles and conducts the electrical impulse from the AV node to the ventricles. 4.) Purkinje fibers: These are a network of specialized cardiac muscle cells that extend throughout the ventricles and coordinate the contraction of the ventricular muscle.
pressure volume diagram
A-B: ejection of the blood into aorta B-C: Isovolumic contraction C-D: Isovolumic relaxation D-A: Passive filling and atrial contraction a.) aortic valve opens b.) mitral valve opens c.) aortic valve closes d.) mitral valve closes
What are the structural differences between arteries and veins?
Arteries: -Arteries are thicker and more muscular than veins, which helps them withstand the pressure of the blood being pumped through them by the heart. -The walls of arteries are also more elastic, which allows them to expand and contract as the blood is pumped through them. -The walls of arteries also contain smooth muscle tissue, which helps regulate blood flow by contracting and relaxing as needed. -Arteries carry oxygenated blood away from the heart to the body's tissues, with the exception of the pulmonary artery, which carries oxygen-depleted blood from the heart to the lungs for oxygenation. Veins: -Veins are thinner and less muscular than arteries, and have weaker walls that are less elastic. -The walls of veins contain less smooth muscle tissue than arteries, so they are not as effective at regulating blood flow. -Veins carry deoxygenated blood back to the heart, with the exception of the pulmonary vein, which carries oxygenated blood from the lungs to the heart. -Veins also have valves, which help prevent the backflow of blood as it is pumped back to the heart.
Describe the roles of each type of vessel
Arteries: Arteries are blood vessels that carry oxygenated blood away from the heart to the body's tissues and are known as pressure reservoirs. They release pressure though elastic recoil. The walls of arteries are thick and elastic, and they contain smooth muscle tissue that helps regulate blood flow by contracting and relaxing as needed. Arteries branch off into smaller arteries, called arterioles which provide varable resistance, which then branch off into even smaller blood vessels called capillaries. Veins: Veins are blood vessels that carry deoxygenated blood back to the heart. The walls of veins are thinner and less elastic than those of arteries, and they contain valves to help prevent the backflow of blood. Veins also branch off into smaller veins, called venules, which then connect to capillaries. Capillaries: Capillaries are the smallest and most numerous blood vessels in the body. The leaky epithelium is only one cell thick, and they are responsible for exchanging nutrients, oxygen, and waste products between the blood and the body's tissues. The roles of the different types of blood vessels are closely interconnected and are essential for maintaining the proper functioning of the circulatory system. Arteries carry oxygenated blood away from the heart to the body's tissues, veins carry deoxygenated blood back to the heart, and capillaries facilitate the exchange of nutrients, oxygen, and waste products between the blood and the body's tissues.
How a clinician measures BP and what it means, including ranges that suggest a healthy CV system or a disease/pathophysiological process
Blood pressure (BP) is typically measured using a device called a sphygmomanometer, which consists of an inflatable cuff, a pressure gauge, and a stethoscope. To measure BP, the clinician will place the cuff around the upper arm and inflate it to a level above the expected systolic blood pressure. The clinician will then slowly release the pressure in the cuff while listening through the stethoscope for the sound of blood flow in the arteries. The point at which the sound of blood flow is first heard is the systolic blood pressure, and the point at which the sound disappears is the diastolic blood pressure. Normal blood pressure is generally considered to be a reading of less than 120/80 mmHg. However, blood pressure can vary depending on a person's age, sex, and other factors, and it is important to work with a healthcare provider to determine what is considered normal for an individual. Higher-than-normal blood pressure (also known as hypertension) can be a sign of a problem with the cardiovascular (CV) system, and it is a major risk factor for heart disease and stroke. On the other hand, lower-than-normal blood pressure (also known as hypotension) can also be a sign of a problem with the CV system, and it can lead to symptoms such as dizziness, lightheadedness, and fainting
Difference between systolic BP and diastolic BP
Blood pressure is highest in the arteries and decreases continuously as blood flows through the circulatory system. Blood pressure is the measure of the force of blood flow against the walls of the arteries. Systolic blood pressure: The systolic blood pressure is the highest blood pressure reading, and it reflects the pressure in the arteries when the heart is contracting (also known as systole). This is the first number in a blood pressure reading (e.g., 120 mmHg in a reading of 120/80 mmHg). Diastolic blood pressure: The diastolic blood pressure is the lowest blood pressure reading, and it reflects the pressure in the arteries when the heart is relaxing (also known as diastole). This is the second number in a blood pressure reading (e.g., 80 mmHg in a reading of 120/80 mmHg). Normal blood pressure is generally considered to be a reading of less than 120/80 mmHg.
factors that influence vasculature radius
Blood pressure: The pressure of the blood in the arteries can influence the radius of the blood vessels. If the blood pressure is high, it can cause the blood vessels to constrict, decreasing their radius. If the blood pressure is low, it can cause the blood vessels to dilate, increasing their radius. Arterial tone: The tone of the arteries, which is determined by the contraction of the smooth muscle in the walls of the arteries, can also affect the radius of the blood vessels. If the arteries are more relaxed, the radius may be larger, while if the arteries are more contracted, the radius may be smaller. Vasodilation and vasoconstriction: The widening or narrowing of the arteries, known as vasodilation and vasoconstriction, respectively, can also influence the radius of the blood vessels. Vasodilation, which is the widening of the arteries, can increase the radius, while vasoconstriction, which is the narrowing of the arteries, can decrease the radius. Hormonal influences: Hormones such as adrenaline and noradrenaline can also influence the radius of the blood vessels. These hormones can cause the arteries to constrict, decreasing the radius, or to dilate, increasing the radius. Temperature: The temperature of the body can also affect the radius of the blood vessels. In general, as the body's temperature increases, the radius of the blood vessels increases, and as the body's temperature decreases, the radius of the blood vessels decreases.
How is this AP different from other APs you've learned about this semester?
Cardiac Muscle: The refectory period last almost as long as the entire muscle twitch. The long refractory period is a cardiac muscle that prevents tetanus Skeletal Muscle: The refractory period is very short compared with the amount of time required for the development of tension. Muscles are stimulated repeatedly will exhibit summation and tetanus
What is cardiac output and how do you calculate it?
Cardiac output is a measure of the amount of blood pumped by the heart in a given time period. It is usually expressed in liters per minute (L/min). Cardiac output is an important measure of the heart's function and can be used to diagnose and monitor various heart conditions. Cardiac output = Stroke volume x Heart rate Stroke volume is the amount of blood pumped by the heart with each contraction. It is usually measured in milliliters (mL). Heart rate is the number of heartbeats per minute.
How does the cell remain in a depolarized state (plateau) and why?
During the plateau phase of the cardiac action potential, the cell remains in a partially depolarized state. This occurs because the cell's ion channels are in a balance between opening and closing, allowing both positive and negative ions to flow into and out of the cell. The cell remails in depolarizing state by the cross bridging cycling: (1) As Ca2+ enters the sarcoplasm, it binds to troponin which begins the crossbridge cycling within the sarcomere (similar to what happens in skeletal muscle) (2) Tropomyosin is pulled off the myosin binding sites (3) myosin and actin bind togetherè slide past one another, shortening the sarcomere
blood flow through the cardiovascular system
From the right atrium, blood flows into the right ventricle of the heart. From there it is pumped through the pulmonary arteries to the lungs, where it is oxygenated. From the lungs, blood travels to the left side of the heart through the pulmonary veins. The blood vessels that go from the right ventricle to the lungs and back to the left atrium are known collectively as the pulmonary circulation. Blood from the lungs enters the heart at the left atrium and passes into the left ventricle. Blood pumped out of the left ventricle enters the large artery known as the aorta. The aorta branches into a series of smaller and smaller arteries that finally lead into networks of capillaries. The first branch represents the coronary arteries, which nourish the heart muscle itself. Blood from these arteries flows into capillaries, then into the coronary veins, which empty directly into the right atrium at the coronary sinus. Ascending branches of the aorta go to the arms, head, and brain. The abdominal aorta supplies blood to the trunk, the legs, and the internal organs such as liver (hepatic artery), digestive tract, and the kidneys (renal arteries). After leaving the capillaries, blood flows into the venous side of the circulation, moving from small veins into larger and larger veins. The veins from the upper part of the body join to form the superior vena cava. Those from the lower part of the body form the inferior vena cava. The two venae cavae empty into the right atrium. The blood vessels that carry blood from the left side of the heart to the tissues and back to the right side of the heart are collectively known as the systemic circulation.
describe homeostatic control of MAP and the baroreceptor reflex.
Homeostatic control of mean arterial pressure (MAP) refers to the body's ability to maintain a relatively stable level of MAP, despite changes in other physiological factors. The baroreceptor reflex is a key component of this homeostatic control system, and it helps to regulate MAP by detecting changes in blood pressure and adjusting the body's response accordingly. The baroreceptors are specialized nerve cells that are located in the walls of the arteries, particularly in the aorta and carotid arteries. They are sensitive to changes in blood pressure, and they send signals to the brain when blood pressure changes occur. When blood pressure increases, the baroreceptors send a signal to the brain, which activates the baroreceptor reflex. This reflex causes a number of physiological responses that help to decrease blood pressure, including: - Vasodilation: The widening of the blood vessels, which decreases resistance to blood flow and lowers blood pressure. - Decreased heart rate: The slowing of the heart rate, which decreases cardiac output and lowers blood pressure. - Decreased contractility: The reduction of the strength of the heart's contractions, which decreases cardiac output and lowers blood pressure. On the other hand, when blood pressure decreases, the baroreceptors send a signal to the brain, which activates the baroreceptor reflex in the opposite direction. This reflex causes a number of physiological responses that help to increase blood pressure, including: - Vasoconstriction: The narrowing of the blood vessels, which increases resistance to blood flow and raises blood pressure. - Increased heart rate: The acceleration of the heart rate, which increases cardiac output and raises blood pressure. - Increased contractility: The increase in the strength of the heart's contractions, which increases cardiac output and raises blood pressure.
how does pressure and velocity of flow changes for each type of vessel.
In general, the pressure and velocity of blood flow are highest in the arteries, which carry oxygenated blood away from the heart to the body's tissues. The walls of the arteries are thick and elastic, and they contain smooth muscle tissue that helps regulate blood flow by contracting and relaxing as needed. The high pressure and velocity of blood flow in the arteries are necessary to ensure that oxygen and nutrients are delivered effectively to the body's tissues. The pressure and velocity of blood flow are generally lower in the veins, which carry deoxygenated blood back to the heart. The walls of the veins are thinner and less elastic than those of the arteries, and they contain valves to help prevent the backflow of blood. The lower pressure and velocity of blood flow in the veins are necessary to allow for the exchange of oxygen and nutrients between the blood and the body's tissues. The pressure and velocity of blood flow are lowest in the capillaries, which are the smallest and most numerous blood vessels in the body. The capillaries are only one cell thick, and they are responsible for exchanging nutrients, oxygen, and waste products between the blood and the body's tissues. The low pressure and velocity of blood flow in the capillaries allow for the exchange of these substances to take place effectively.
what MAP is and be able to calculate
Mean arterial pressure (MAP) is a measure of the average blood pressure in the arteries. It is an important indicator of the perfusion (blood flow) of the body's tissues, and it is often used to assess the effectiveness of blood flow in the body. To calculate MAP, the following equation is used: MAP = [(2 x diastolic blood pressure) + systolic blood pressure] / 3. Normal MAP is generally considered to be between 70-100 mmHg.
diagram, identify and explain the components of an ECG
P waves: These represent the contraction of the atria (the two upper chambers of the heart). P waves are usually small and rounded. PR segment: conduction through AV node and AV bundle QRS complex: This represents the contraction of the ventricles (the two lower chambers of the heart). The QRS complex is usually the largest waveform on the ECG trace and is made up of three smaller waves: the Q wave, the R wave, and the S wave. T waves: These represent the relaxation of the ventricles after contraction. T waves are usually smaller than the QRS complex and have a more rounded shape. ST segment: This represents the period of time between the end of the QRS complex and the beginning of the T wave. The ST segment should be relatively flat, indicating that the ventricles are not contracting or relaxing. U waves: These may be present on some ECG traces and are thought to represent the recovery of the ventricles after contraction. U waves are usually small and rounded, and may follow the T wave.
the properties of cardiac myocardial cells (pacemaker and contractile)
Pacemaker cells: Pacemaker cells are specialized cardiac muscle cells that are responsible for generating electrical impulses that initiate each heartbeat. These cells have a high density of ion channels, which allows them to generate spontaneous electrical impulses. Pacemaker cells are found in specialized areas of the heart, such as the sinoatrial (SA) node and the atrioventricular (AV) node. Contractile cells: Contractile cells are the main cardiac muscle cells that are responsible for contracting and relaxing to pump blood. These cells have a high density of mitochondria, which allows them to generate the energy needed for contraction. Contractile cells are found throughout the heart and are responsible for the coordinated contraction of the heart muscle. Both pacemaker and contractile cells are important for the proper functioning of the heart. Pacemaker cells initiate the electrical signals that trigger contraction, while contractile cells generate the force needed to pump blood throughout the body.
Describe the cardiac action potential
Phase 4: resting membrane potential. Myocardial contractile cells have a stable resting potential of about Phase 0: depolarization. When a wave of depolarization moves into a contractile cell through gap junctions, the membrane potential becomes more positive. Voltage-gated channels open, allowing to enter the cell and rapidly depolarize it. The membrane potential reaches about before the channels close. These are double-gated channels, similar to the voltage-gated channels of the axon. Phase 1: initial repolarization. When the channels close, the cell begins to repolarize as leaves through open channels. Phase 2: the plateau. The initial repolarization is very brief. The action potential then flattens into a plateau as the result of two events: a decrease in permeability and an increase in permeability. Voltage-gated channels activated by depolarization have been slowly opening during phases 0 and 1. When they finally open, enters the cell. At the same time, some "fast" channels close. The combination of influx and decreased efflux causes the action potential to flatten out into a plateau. Phase 3: rapid repolarization. The plateau ends when channels close and permeability increases once more. The "slow" channels responsible for this phase are similar to those in the neuron: They are activated by depolarization but are slow to open. When the slow channels open, exits rapidly, returning the cell to its resting potential (ph
describe the relationship between pressure, flow [rate] and resistance
Pressure: Pressure is the measure of the force of blood flow against the walls of the arteries. It is expressed in units of millimeters of mercury (mmHg). The higher the pressure, the greater the force of the blood flow. Flow rate: Flow rate is the measure of the volume of blood that is flowing through the arteries per unit of time. It is expressed in units of milliliters per minute (mL/min). The higher the flow rate, the more blood is being pumped through the arteries. Resistance: Resistance is the measure of the opposition to blood flow in the arteries. It is expressed in units of mmHg per mL/min. The higher the resistance, the harder it is for blood to flow through the arteries. The relationship between pressure, flow rate, and resistance can be described using the equation: Pressure = Flow rate x Resistance. This equation is known as Poiseuille's law, and it illustrates the relationship between these three factors in the circulatory system. R = (8*Length*viscosity)/(pi*radius^4)
What is the purpose of the coronary arteries? What are the branches of the right and left coronary arteries?
Purpose: Arteries that supply blood to the heart muscle The branches of the left and right coronary arteries are the circumflex branch of LCA, the Anterior interventricular branch of LCA, and the posterior interventricular branch of RCA.
the primary difference(s) between the right and left sides of the heart
Right Heart = receives blood from the tissues and sends it to the lungs for oxygenation Left Heart = receives newly oxygenated blood from the lungs and pumps it to tissues throughout the body
What variables affect heart rate and stroke volume (and therefore, cardiac output)?
Stroke Volume: a. Preload: venous return b. Contractility; force of heart contraction c. Afterload: systemic vascular resistance heart Rate: a. SNS (sympathetic nervous system) b. PNS (parasympathetic nervous system)
describe how the autonomic division modulates cardiovascular responses: heart rate, force and arteriole resistance.
The autonomic division of the nervous system is responsible for controlling the body's involuntary functions, including those of the cardiovascular system. The autonomic division consists of two branches: the sympathetic nervous system and the parasympathetic nervous system. The sympathetic nervous system is responsible for activating the body's "fight or flight" response, which is a response to perceived threats or stressors. When the sympathetic nervous system is activated, it causes a number of physiological responses that are designed to increase the body's ability to respond to the threat or stressor. These responses include: Increased heart rate: The sympathetic nervous system increases the heart rate, which increases cardiac output and blood pressure. Increased contractility: The sympathetic nervous system increases the strength of the heart's contractions, which also increases cardiac output and blood pressure. Vasoconstriction: The sympathetic nervous system causes the blood vessels to constrict, which increases resistance to blood flow and raises blood pressure. The parasympathetic nervous system, on the other hand, is responsible for activating the body's "rest and digest" response, which is a response to relaxation and rest. When the parasympathetic nervous system is activated, it causes a number of physiological responses that are designed to decrease the body's activity level and conserve energy. These responses include: Decreased heart rate: The parasympathetic nervous system decreases the heart rate, which decreases cardiac output and blood pressure. Decreased contractility: The parasympathetic nervous system decreases the strength of the heart's contractions, which also decreases cardiac output and blood pressure. Vasodilation: The parasympathetic nervous system causes the blood vessels to dilate, which decreases resistance to blood flow and lowers blood pressure.
describe the mechanisms of exchange in the capillaries.
The capillaries are the smallest and most numerous blood vessels in the body, and they play a crucial role in the exchange of nutrients, oxygen, and waste products between the blood and the body's tissues. The mechanisms of exchange in the capillaries involve diffusion, filtration, and reabsorption. Diffusion: Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration. In the capillaries, oxygen and nutrients in the blood diffuse into the surrounding tissue, while waste products in the tissue diffuse into the blood. Filtration: Filtration is the movement of fluids and dissolved substances through a membrane. In the capillaries, filtration occurs as blood passes through the walls of the capillaries and into the surrounding tissue. This filtration helps to remove waste products from the blood and maintain the balance of fluids in the body. Reabsorption: Reabsorption is the process by which substances are taken back up into the circulatory system from the surrounding tissue. In the capillaries, reabsorption occurs as the body takes up nutrients and other important substances from the tissue and returns them to the circulation.
how the signal travels through the conduction system?
The electrical signal is initiated by the SA node, which generates a spontaneous electrical impulse that travels through the atria, causing them to contract and pump blood into the ventricles. The impulse is then conducted to the AV node, where it is briefly delayed to allow the atria to fully contract. From the AV node, the impulse is conducted through the AV bundle and Purkinje fibers to the ventricles, causing them to contract and pump blood out of the heart.
explain the components of an electrocardiogram (ECG) assessment
The father of the modern ECG was a Dutch physiologist named Walter Einthoven. He named the parts of the ECG as we know them today and created "Einthoven's triangle," a hypothetical triangle created around the heart when electrodes are placed on both arms and the left leg. The sides of the triangle are numbered to correspond with the three leads ("leeds"), or pairs of electrodes, used for a recording.An ECG is recorded from one lead at a time. One electrode acts as the positive electrode of a lead, and a second electrode acts as the negative electrode of the lead. (The third electrode is inactive). For example, in lead I, the left arm electrode is designated as positive and the right arm electrode is designated as negative. When an electrical wave moving through the heart is directed toward the positive electrode, the ECG wave goes up from the baseline (Fig. 14.156d). If net charge movement through the heart is toward the negative electrode, the wave points downward.
How does the heart accommodate its own high energy demands?
The high energy demands of contracting constantly require a continuous supply of nutrients and oxygen to the heart muscle.
What are the general differences between the pulmonary and systemic vessels?
The pulmonary vessels are the blood vessels that carry blood between the heart and the lungs, while the systemic vessels are the blood vessels that carry blood to and from the rest of the body. There are several key differences between the pulmonary and systemic vessels: -Function: The primary function of the pulmonary vessels is to transport oxygen-depleted blood from the heart to the lungs, where it is oxygenated, and then carry oxygenated blood back to the heart. The systemic vessels, on the other hand, carry oxygenated blood from the heart to the body's tissues, and carry deoxygenated blood back to the heart. -Oxygen content: The blood in the pulmonary vessels is low in oxygen and high in carbon dioxide, while the blood in the systemic vessels is high in oxygen and low in carbon dioxide. -Blood pressure: The blood pressure in the pulmonary vessels is generally lower than in the systemic vessels, due to the lower resistance to blood flow in the lungs. -Wall thickness: The walls of the pulmonary vessels are generally thinner than those of the systemic vessels, due to the lower blood pressure and lower resistance to blood flow in the lungs. -Valve presence: The pulmonary veins, which carry oxygenated blood from the lungs to the heart, have valves to prevent backflow of blood. The pulmonary arteries, on the other hand, do not have valves. The systemic veins and arteries, on the other hand, have valves to prevent backflow of blood.
