Physiology of Cardiovascular System
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Questions and Answers

What percentage of the body weight is made up of blood in humans?

  • 11-12%
  • 7-8% (correct)
  • 9-10%
  • 5-6%

    • What is the main function of deposited blood?

  • To increase the mass of circulating blood in response to hypoxia or physical strain (correct)
  • To decrease the heart rate
  • To increase oxygen consumption
  • To decrease blood pressure

    • What percentage of blood is stored in the liver as a blood depot organ?

  • 10-15%
  • 25-30%
  • 20-25%
  • 15-20% (correct)

    • What is the primary function of albumins in blood plasma?

    <p>To create colloid osmotic pressure</p> Signup and view all the answers

    What is the term for the pressure exerted by proteins in blood plasma?

    <p>Oncotic pressure</p> Signup and view all the answers

    What is the primary function of globulins in blood plasma?

    <p>To fight infections and illness</p> Signup and view all the answers

    Where are globulins primarily produced?

    <p>Bone marrow, spleen, and lymph nodes</p> Signup and view all the answers

    What is the term for the ability of proteins to draw water into capillaries?

    <p>Oncotic pressure</p> Signup and view all the answers

    What is the approximate percentage of blood plasma in the bloodstream?

    <p>50-60%</p> Signup and view all the answers

    Which of the following is NOT a function of the blood system?

    <p>Digestion of nutrients</p> Signup and view all the answers

    What is the role of fibrinogen in blood plasma?

    <p>Participation in blood clotting</p> Signup and view all the answers

    What is the main function of plasma proteins in the body?

    <p>Supply of nutrients for the body's plastic and energetic processes</p> Signup and view all the answers

    What is the role of oncotic pressure in the capillaries?

    <p>Filtration and reabsorption</p> Signup and view all the answers

    What percentage of osmotic pressure is contributed by proteins in the blood plasma?

    <p>0.5%</p> Signup and view all the answers

    What is the main component of inorganic substances in the blood plasma?

    <p>NaCl</p> Signup and view all the answers

    What is the purpose of supplementing cattle diets with urea?

    <p>To aid in the production of protein by rumen microbes</p> Signup and view all the answers

    What is the term used to refer to the large molecular weight particles present in a solution?

    <p>Colloids</p> Signup and view all the answers

    What is the main factor that determines the blood plasma osmotic pressure?

    <p>Concentration of salts and ions</p> Signup and view all the answers

    What is the condition that occurs when excessive quantities of water are ingested?

    <p>Water intoxication</p> Signup and view all the answers

    Why does the camel not show signs of water intoxication after drinking a large amount of water?

    <p>The camel's body is able to regulate the balance of electrolytes</p> Signup and view all the answers

    What is the main function of white blood cells?

    <p>Defense function</p> Signup and view all the answers

    What is the term for the process of transporting heat throughout the body to equalize temperature?

    <p>Thermoregulation</p> Signup and view all the answers

    Which type of connective tissue is characterized by a high degree of flexibility and is found in the ears and nose?

    <p>Cartilage</p> Signup and view all the answers

    What is the primary function of platelets in the blood?

    <p>Blood clotting</p> Signup and view all the answers

    What is the term for the process of supplying nutrients and removing waste products from cells?

    <p>Transport function</p> Signup and view all the answers

    What is the term for the regulation of bodily functions through chemical signals?

    <p>Humoral regulation</p> Signup and view all the answers

    What is the term for the fluid that circulates in the body and makes up a part of the internal environment?

    <p>Blood</p> Signup and view all the answers

    What is the term for the process of maintaining a relatively constant concentration of solutes, temperature, and pH in the body?

    <p>Homeostasis</p> Signup and view all the answers

    Which type of connective tissue is characterized by a high degree of flexibility and is found in adipose tissue?

    <p>Loose connective tissue</p> Signup and view all the answers

    What is the term for the process of exchanging oxygen and carbon dioxide between the lungs and the body?

    <p>Respiratory function</p> Signup and view all the answers

    What is the significance of the oval shape of RBCs in camels?

    <p>It enables the RBCs to expand to 240% of their original volume</p> Signup and view all the answers

    What is the pH range of animal blood?

    <p>pH 7.35-7.45</p> Signup and view all the answers

    What is the primary function of the carbonate system in maintaining blood pH?

    <p>It ensures a normal pH very quickly through CO2 exhalation</p> Signup and view all the answers

    What is the response of the respiratory system to high CO2 levels in the arterial blood?

    <p>It increases the rate and depth of breathing</p> Signup and view all the answers

    What is the function of the renal system in maintaining blood pH?

    <p>It excretes various phosphates with urine as needed</p> Signup and view all the answers

    What happens to the blood pH during intense muscle work?

    <p>It becomes more acidic</p> Signup and view all the answers

    What is the effect of intensified breathing on blood pH?

    <p>It shifts the blood pH to the alkaline side</p> Signup and view all the answers

    What is the response of the renal system to acidosis?

    <p>It increases the reabsorption of bicarbonate</p> Signup and view all the answers

    What is the effect of unventilated rooms with high CO2 concentrations on blood pH?

    <p>It shifts the blood pH to the acidic side</p> Signup and view all the answers

    What is the third line of defense in maintaining blood pH?

    <p>The excretory organs</p> Signup and view all the answers

    What is the primary function of red blood cells?

    <p>To maintain pH levels and perform gas exchange</p> Signup and view all the answers

    What is the term for the formation of red blood cells?

    <p>Erythropoiesis</p> Signup and view all the answers

    What stimulates erythropoiesis?

    <p>Decreased oxygen levels in the blood</p> Signup and view all the answers

    What is the term for the condition in which tissues do not have enough oxygen due to a lack of oxygen in the blood?

    <p>Hypoxic hypoxia</p> Signup and view all the answers

    How many days does it take to produce new erythrocytes?

    <p>7 days</p> Signup and view all the answers

    Where are erythrocytes continuously produced?

    <p>In the red bone marrow of large bones</p> Signup and view all the answers

    What is the role of hemoglobin in red blood cells?

    <p>To give RBCs their red color and bind oxygen</p> Signup and view all the answers

    How many RBCs are found per mm3 in goats' blood?

    <p>14 million</p> Signup and view all the answers

    What is the main function of haptoglobin in the body?

    <p>To clear free hemoglobin</p> Signup and view all the answers

    What is the main function of neutrophils in the body?

    <p>To form pus in response to a foreign substance</p> Signup and view all the answers

    What is the function of sympathetic nerves in terms of erythropoiesis?

    <p>Activate EPO production</p> Signup and view all the answers

    Where does leukopoiesis occur?

    <p>In the red bone marrow</p> Signup and view all the answers

    What is the primary function of the spleen in physiological hemolysis?

    <p>To filter out damaged cells</p> Signup and view all the answers

    What is the role of platelets in the first stage of hemostasis?

    <p>To stick to the edges of the wound and form a platelet plug</p> Signup and view all the answers

    What is the primary function of macrophages?

    <p>To perform phagocytosis</p> Signup and view all the answers

    What is the fate of hemoglobin released during physiological hemolysis?

    <p>It is converted to bilirubin and excreted in the bile</p> Signup and view all the answers

    What is the term for the process of forming platelets?

    <p>Thrombopoiesis</p> Signup and view all the answers

    What is the role of macrophages in physiological hemolysis?

    <p>To recognize and phagocytize damaged RBCs</p> Signup and view all the answers

    What is the final stage of hemostasis?

    <p>Ingrowth of fibrous tissue into a blood clot</p> Signup and view all the answers

    What is the effect of increased hemolysis on the body?

    <p>It leads to anemia and reduced oxygen delivery to tissues</p> Signup and view all the answers

    What is the role of haptoglobin in the metabolism of hemoglobin?

    <p>It transports hemoglobin to the liver for metabolism</p> Signup and view all the answers

    What is the role of lymphocytes in the body?

    <p>To produce antibodies</p> Signup and view all the answers

    What is the fate of iron released during physiological hemolysis?

    <p>It is reused for hemoglobin synthesis</p> Signup and view all the answers

    What is the function of corticotropin in the regulation of erythropoiesis?

    <p>It stimulates the synthesis of corticosteroids</p> Signup and view all the answers

    What is the life span of a red blood cell?

    <p>120 days</p> Signup and view all the answers

    What is the role of the liver in the metabolism of bilirubin?

    <p>It excretes bilirubin into the bile</p> Signup and view all the answers

    What is the main reason why tissues are unable to use oxygen in histotoxic hypoxia?

    <p>The presence of carbon monoxide</p> Signup and view all the answers

    What is the primary function of erythropoietin (EPO) in the body?

    <p>To promote the production of red blood cells in the bone marrow</p> Signup and view all the answers

    Which of the following hormones inhibits the effect of erythropoietin (EPO) on hematopoietic cells?

    <p>Estrogenic hormones</p> Signup and view all the answers

    What is the term for the process of producing platelets in the bone marrow?

    <p>Thrombopoiesis</p> Signup and view all the answers

    What is the function of the glycoprotein hormone produced by the liver and kidney?

    <p>To regulate the production of platelets</p> Signup and view all the answers

    What is the term for the category of substances produced by neutrophils when they encounter a foreign antigen?

    <p>Leukopoietin</p> Signup and view all the answers

    What is the result of the absence of erythropoietin, leukopoietin, and thrombopoietin in the body?

    <p>Anemia, leukopenia, and thrombocytopenia</p> Signup and view all the answers

    What is the function of nitric oxide in the body?

    <p>To regulate vascular tone</p> Signup and view all the answers

    What is the term for the process of transporting oxygen from the lungs to the tissues?

    <p>Oxygenation</p> Signup and view all the answers

    What is the primary response of blood vessels to vascular damage?

    <p>Constriction of blood vessels</p> Signup and view all the answers

    What is the result of platelet activation and aggregation?

    <p>Formation of a primary platelet plug</p> Signup and view all the answers

    What is the role of thromboplastinogen in the formation of a definitive blood plug?

    <p>Release of thromboplastinogen, which turns into thromboplastin</p> Signup and view all the answers

    What is necessary for blood clotting to occur?

    <p>Both A and B</p> Signup and view all the answers

    Why does blood not clot in blood vessels under normal conditions?

    <p>Because of the anticoagulant system in the body</p> Signup and view all the answers

    What is the term for the multi-step process of forming a definitive blood plug?

    <p>Coagulation</p> Signup and view all the answers

    What is the final step in the formation of a definitive blood plug?

    <p>Ingrowth of fibrous tissue</p> Signup and view all the answers

    What is the purpose of the prothrombin activator complex?

    <p>To transform prothrombin into thrombin</p> Signup and view all the answers

    What is the role of serotonin in the formation of a primary platelet plug?

    <p>Activation of platelets</p> Signup and view all the answers

    What is the term for the entire process of stopping bleeding after vascular damage?

    <p>Hemostasis</p> Signup and view all the answers

    Which type of resistance in blood vessels is mainly caused by the elasticity of the aorta and large arteries?

    <p>Elastic resistance</p> Signup and view all the answers

    What is the effect of increasing the cross-sectional area of blood vessels on resistance?

    <p>It decreases the resistance</p> Signup and view all the answers

    What is the function of capillaries in the circulatory system?

    <p>To deliver blood close to tissues</p> Signup and view all the answers

    What is the effect of shortening a blood vessel on its resistance?

    <p>It decreases the resistance</p> Signup and view all the answers

    What is the role of the elasticity of the aortic wall in the bloodstream?

    <p>To maintain a continuous flow of blood in the vessels</p> Signup and view all the answers

    What is the main function of arteries in the circulatory system?

    <p>To act as resistance blood vessels</p> Signup and view all the answers

    What is the effect of increasing the diameter of small arteries and arterioles on blood flow?

    <p>It increases the blood flow</p> Signup and view all the answers

    What is the main function of veins in the circulatory system?

    <p>To act as capacitance or volume blood vessels</p> Signup and view all the answers

    What is the effect of aging on the elasticity of the aortic wall?

    <p>It decreases the elasticity</p> Signup and view all the answers

    What is the significance of the arrangement of organs in parallel in the circulatory system?

    <p>It ensures that all the blood pumped from the right ventricle enters the lungs</p> Signup and view all the answers

    What is the primary factor that determines the linear velocity of blood flow?

    <p>Total cross-sectional area of the blood vessels</p> Signup and view all the answers

    What is the effect of increased blood viscosity on blood flow?

    <p>It decreases blood flow</p> Signup and view all the answers

    What is the primary determinant of blood vessel diameter?

    <p>Vascular tone</p> Signup and view all the answers

    What is the relationship between blood vessel diameter and resistance?

    <p>Inversely proportional</p> Signup and view all the answers

    What is the term for the time in which one blood particle passes through both circuits?

    <p>Blood circulation time</p> Signup and view all the answers

    What is the primary factor that affects the blood flow in capillaries?

    <p>Time for exchange of gases and nutrients</p> Signup and view all the answers

    What is the effect of decreased liver function on blood viscosity?

    <p>It decreases blood viscosity</p> Signup and view all the answers

    What is the relationship between linear velocity of blood flow and total cross-sectional area of the blood vessels?

    <p>Inversely proportional</p> Signup and view all the answers

    What is the term for the resistance that must be overcome to push blood through the circulatory system?

    <p>Vascular resistance</p> Signup and view all the answers

    What is the effect of polycythemia on blood viscosity?

    <p>It increases blood viscosity</p> Signup and view all the answers

    What is the primary mechanism by which pain irritates the sympathetic nervous system, increasing the release of epinephrine and promoting blood clot formation?

    <p>Narrowing of blood vessels</p> Signup and view all the answers

    What is the role of thromboxane A2 in hemostasis?

    <p>Stimulating platelet aggregation</p> Signup and view all the answers

    What is the main difference between the pulmonary and systemic circuits?

    <p>Gas exchange</p> Signup and view all the answers

    What is the primary factor that determines cardiac output?

    <p>Stroke volume</p> Signup and view all the answers

    What is the role of CaCl2 in blood clot formation?

    <p>Enhancing coagulation</p> Signup and view all the answers

    What is the effect of sympathetic stimulation on stroke volume?

    <p>Increase</p> Signup and view all the answers

    What is the term for the amount of blood pumped out of each ventricle with each contraction?

    <p>Stroke volume</p> Signup and view all the answers

    What is the primary function of the pulmonary circuit?

    <p>Oxygenation of blood</p> Signup and view all the answers

    What is the term for the pressure exerted by blood on the blood vessel walls?

    <p>Blood pressure</p> Signup and view all the answers

    What is the role of serotonin in blood clot formation?

    <p>Promoting platelet aggregation</p> Signup and view all the answers

    What is the main advantage of the heart's parallel circulatory system?

    <p>Improved local regulation of blood flow</p> Signup and view all the answers

    What would be the consequence if the heart's circulatory system was in series?

    <p>Blood would lose pressure, oxygen, and nutrients</p> Signup and view all the answers

    What is the term for the relaxation of the heart muscle?

    <p>Diastole</p> Signup and view all the answers

    What are the two separate pumps that make up the heart?

    <p>Systemic and pulmonary pumps</p> Signup and view all the answers

    What is the term for the ability of muscle tissue to respond to stimuli?

    <p>Excitability</p> Signup and view all the answers

    What is the main function of the heart as a 'pressure pump'?

    <p>To eject blood during ventricular systole</p> Signup and view all the answers

    What is the term for the force of contraction of cardiac muscle?

    <p>Contractility</p> Signup and view all the answers

    What is the property of cardiac muscle that allows it to conduct excitation?

    <p>Conductivity</p> Signup and view all the answers

    What is the term for the heart's ability to suck blood from the veins?

    <p>Suction pump</p> Signup and view all the answers

    What are the two functional properties of the myocardium that enable the heart's pump function?

    <p>Structures and functional properties</p> Signup and view all the answers

    What is the term for the ability of the heart muscle to contract rhythmically without external stimulation?

    <p>Automaticity</p> Signup and view all the answers

    What is the location of the sinoatrial node in mammals?

    <p>Posterior wall of the right atrium</p> Signup and view all the answers

    What is the speed of conduction of excitation in the Bundle of His?

    <p>4 m/sec</p> Signup and view all the answers

    What is the duration of the total diastole or pause in the cardiac cycle in humans?

    <p>0.4 sec</p> Signup and view all the answers

    What percentage of ventricular filling occurs during the ventricular filling phase?

    <p>70-80%</p> Signup and view all the answers

    What is the term for the law that states that a cardiac muscle unit responds maximally to an adequate stimulus?

    <p>All-or-None Law</p> Signup and view all the answers

    What is the location of the atrioventricular node in the heart?

    <p>Interatrial septum</p> Signup and view all the answers

    What is the term for the slow conduction in the atrioventricular node?

    <p>AV delay</p> Signup and view all the answers

    What is the duration of the absolute refractory period in cardiac muscle compared to skeletal muscle?

    <p>0.27 seconds in cardiac muscle and 0.005 seconds in skeletal muscle</p> Signup and view all the answers

    What is the phase when the myocardium is unable to respond to stimuli during the cardiac cycle?

    <p>Absolute refractory period</p> Signup and view all the answers

    What is the duration of the cardiac cycle in horses?

    <p>1.4 sec</p> Signup and view all the answers

    What happens during the early repolarization phase of the cardiac cycle?

    <p>K+ channels open and K+ efflux returns TMP to 0 mV</p> Signup and view all the answers

    What is the term for the process of contraction and relaxation of individual parts of the heart?

    <p>Cardiac cycle</p> Signup and view all the answers

    What is the characteristic of cardiac muscle that prevents it from undergoing summation and tetanus?

    <p>Long absolute refractory period</p> Signup and view all the answers

    What is the phase where the excitability of the heart muscle is slightly increased?

    <p>Supernormal phase</p> Signup and view all the answers

    What is the term for the ability of the heart to contract outside of the normal heartbeat, resulting in an extra systole?

    <p>Extrasystole</p> Signup and view all the answers

    What is the phase where the muscle relaxes, and it can only respond to strong stimuli and cause an action potential?

    <p>Relative refractory period</p> Signup and view all the answers

    What is the term for the period when the myocardium is unable to respond to stimuli, including the absolute refractory period and a short segment of phase 3?

    <p>Effective refractory period</p> Signup and view all the answers

    What is the phase where the influx of Ca2+ is electrically balanced by K+ efflux?

    <p>Plateau phase</p> Signup and view all the answers

    What is the phase where K+ channels remain open and return TMP to -90mV?

    <p>Repolarization phase</p> Signup and view all the answers

    What is the percentage of ventricular filling at the start of atrial systole?

    <p>70-80%</p> Signup and view all the answers

    What happens to the pressure within the ventricles during isovolumetric contraction phase?

    <p>It increases</p> Signup and view all the answers

    During which phase of ventricular systole do the pulmonary and aortic semilunar valves open?

    <p>Ventricular ejection phase</p> Signup and view all the answers

    What happens to the atrioventricular valves during isovolumetric relaxation phase?

    <p>They are closed</p> Signup and view all the answers

    What is the result of the pressure drop in the ventricles during late diastole?

    <p>Blood flows from the atria into the ventricles</p> Signup and view all the answers

    What is the result of the ventricular muscle relaxing during early diastole?

    <p>Pressure on the remaining blood within the ventricle decreases</p> Signup and view all the answers

    During which phase of the cardiac cycle do the ventricles pump the same amount of blood?

    <p>Ventricular systole</p> Signup and view all the answers

    What is the result of the pressure rise in the ventricles during ventricular systole?

    <p>The semilunar valves open</p> Signup and view all the answers

    What happens to the atrial muscles at the start of atrial systole?

    <p>They contract</p> Signup and view all the answers

    What is the result of the atrial contraction during atrial systole?

    <p>Blood is pumped into the ventricles</p> Signup and view all the answers

    What is the primary reason the right ventricle has a lower maximum pressure than the left ventricle?

    <p>The pulmonary circuit is shorter than the systemic circuit.</p> Signup and view all the answers

    What is the function of the atrioventricular valves?

    <p>To ensure blood flow in the circulatory system in only one direction.</p> Signup and view all the answers

    During ventricular systole, what happens to the atrioventricular valves?

    <p>They close to prevent backflow into the atria.</p> Signup and view all the answers

    What is the function of the semilunar valves?

    <p>To prevent backflow into the heart.</p> Signup and view all the answers

    During atrial systole, what happens to the venae cavae and pulmonary veins?

    <p>They close to prevent backflow into the veins.</p> Signup and view all the answers

    What is the function of the myocardial conducting cells?

    <p>To initiate and propagate the action potential that triggers contractions.</p> Signup and view all the answers

    What is the function of the cardiac conduction system?

    <p>To produce sequential, rhythmic electrical activities in the myocardium.</p> Signup and view all the answers

    During ventricular diastole, what happens to the atrioventricular valves?

    <p>They open to allow blood to flow into the ventricles.</p> Signup and view all the answers

    What is the term for the lowest pressure reached in the right atrium during ventricular systole?

    <p>Diastolic pressure.</p> Signup and view all the answers

    What is the function of the atrial systole?

    <p>To increase the pressure inside the atria to open the atrioventricular valves.</p> Signup and view all the answers

    What is the volume of blood in the ventricle at the end of diastole?

    <p>120 mL</p> Signup and view all the answers

    What is the volume of blood ejected by each ventricle in one contraction?

    <p>70 mL</p> Signup and view all the answers

    What can remain constant despite changes in stroke volume during inspiration and expiration?

    <p>Cardiac output</p> Signup and view all the answers

    What is the pressure in the left ventricle and aorta during ventricular systole?

    <p>120 mm Hg</p> Signup and view all the answers

    Which of the following groups should not have a respiratory sinus arrhythmia?

    <p>Cats</p> Signup and view all the answers

    What can the ECG inform about in relation to the heart?

    <p>Origin of excitation</p> Signup and view all the answers

    What is the pressure in the ventricle at the beginning of total diastole?

    <p>10 mm Hg</p> Signup and view all the answers

    What can be judged about from the ECG?

    <p>Cardiac arrhythmias</p> Signup and view all the answers

    Why does the pressure remain high in the aorta during total diastole?

    <p>Due to the resistance of the aorta</p> Signup and view all the answers

    What is the normal rhythm of the heart called?

    <p>Sinus rhythm</p> Signup and view all the answers

    What is the volume of blood remaining in each ventricle after systole?

    <p>50 mL</p> Signup and view all the answers

    What can be inferred about the cardiac conduction system from the ECG?

    <p>All of the above</p> Signup and view all the answers

    What determines the stroke volume?

    <p>The stretching of the ventricle in diastole</p> Signup and view all the answers

    What can be diagnosed with the help of the ECG?

    <p>Heart attack</p> Signup and view all the answers

    What is the purpose of the ventricle's relaxation during total diastole?

    <p>To promote the flow of blood from the atrium</p> Signup and view all the answers

    What can affect the cardiac conduction system?

    <p>All of the above</p> Signup and view all the answers

    Why does the pressure in the ventricle drop sharply during total diastole?

    <p>Due to the relaxation of the ventricle</p> Signup and view all the answers

    What is the significance of the ECG in understanding the heart?

    <p>It provides information about the cardiac conduction system</p> Signup and view all the answers

    What is the result of the ventricle's relaxation during total diastole?

    <p>The ventricle is emptied and begins to take back its shape</p> Signup and view all the answers

    What is the relationship between the ECG and cardiac arrhythmias?

    <p>The ECG can diagnose cardiac arrhythmias</p> Signup and view all the answers

    Which part of the cardiac conduction system generates the most impulses per minute?

    <p>Sinoatrial node</p> Signup and view all the answers

    What is the purpose of the Stannius experiment?

    <p>To show the gradient of automaticity in the heart</p> Signup and view all the answers

    What is the significance of the P wave in an ECG?

    <p>It represents atrial depolarization</p> Signup and view all the answers

    What is the effect of the parasympathetic nervous system on the heart rate?

    <p>It decreases the heart rate</p> Signup and view all the answers

    What is the term for the ability of the heart muscle to depolarize spontaneously?

    <p>Automaticity</p> Signup and view all the answers

    What is the function of the bundle of His in the cardiac conduction system?

    <p>To transmit impulses from the atria to the ventricles</p> Signup and view all the answers

    What is the term for the record of the electrical activity of the heart?

    <p>Electrocardiogram</p> Signup and view all the answers

    What is the significance of the T wave in an ECG?

    <p>It represents the repolarization of the ventricles</p> Signup and view all the answers

    What is the effect of the sympathetic nervous system on the heart rate?

    <p>It increases the heart rate</p> Signup and view all the answers

    What is the term for the irregular sinus arrhythmia that occurs normally in the heart?

    <p>Respiratory sinus arrhythmia</p> Signup and view all the answers

    What determines the flow of blood in the blood vessels?

    <p>The difference in pressure between the beginning and end of the vessel and the total cross-sectional area of the vessel</p> Signup and view all the answers

    Which of the following is the most variable component of total resistance in the circulatory system?

    <p>Peripheral resistance</p> Signup and view all the answers

    What is the main function of the smooth myocytes in the tunica media of blood vessels?

    <p>To control blood flow by changing vessel diameter</p> Signup and view all the answers

    What is the direction of blood flow in a vessel?

    <p>From higher to lower pressure</p> Signup and view all the answers

    Which layer of blood vessels consists of endothelial cells, basal membrane, and connective tissue?

    <p>Tunica interna</p> Signup and view all the answers

    What type of fibers are found in the external layer of blood vessels?

    <p>Collagen fibers</p> Signup and view all the answers

    What is the formula that relates blood flow rate (Q) to pressure difference and resistance?

    <p>Q = (P1 – P2) / R</p> Signup and view all the answers

    What is the primary function of changes in blood vessel diameter?

    <p>To regulate blood supply to organs and tissues</p> Signup and view all the answers

    Which of the following factors affects total resistance in the circulatory system?

    <p>All of the above</p> Signup and view all the answers

    What is the name of the level of blood circulation that ensures blood circulation throughout the system?

    <p>Systemic hemodynamics</p> Signup and view all the answers

    What is the effect of increasing the total cross-sectional area of a vessel on blood flow?

    <p>It increases blood flow</p> Signup and view all the answers

    What is the term for the closed circuit formed by the heart and blood vessels?

    <p>Closed circulatory system</p> Signup and view all the answers

    Which of the following is an example of a physiological change in peripheral resistance?

    <p>All of the above</p> Signup and view all the answers

    What is the effect of decreasing the resistance (R) in the formula Q = (P1 – P2) / R?

    <p>It increases blood flow</p> Signup and view all the answers

    What is the primary function of Level 2 blood circulation?

    <p>To provide blood supply to organs and tissues</p> Signup and view all the answers

    What is the name of the level of blood circulation that occurs through small blood vessels - capillaries?

    <p>Microcirculation</p> Signup and view all the answers

    What is the primary function of smooth myocytes in large veins?

    <p>To change blood vessel diameter</p> Signup and view all the answers

    What is the term for the ability of organs to self-regulate their blood flow?

    <p>Local regulation</p> Signup and view all the answers

    What is the primary function of the right and left heart pumps?

    <p>To maintain circulation in the pulmonary and systemic circuits</p> Signup and view all the answers

    What is the term for the process of blood circulation in the cardiovascular system?

    <p>Hemodynamics</p> Signup and view all the answers

    What is the term used to describe the regulation of cardiac function that relates the force of contraction to the degree of stretch of cardiac muscle fibers?

    <p>Heterometric regulation</p> Signup and view all the answers

    Which of the following parameters is NOT adjusted by intrinsic and extrinsic factors to regulate cardiac output?

    <p>Blood pressure</p> Signup and view all the answers

    What is the term used to describe the amount of blood that returns to the heart?

    <p>Venous return</p> Signup and view all the answers

    Which of the following is an example of extrinsic regulation of the heart?

    <p>Neural regulation</p> Signup and view all the answers

    What is the term used to describe the degree to which the ventricular walls are stretched at the end of diastole?

    <p>Preload</p> Signup and view all the answers

    Which of the following is a mechanism of intrinsic regulation of the heart?

    <p>Homeometric regulation</p> Signup and view all the answers

    What is the effect of a reduced afterload on the heart's workload?

    <p>Decreases the workload</p> Signup and view all the answers

    What is the effect of an increase in myocardial stretch on the force of heart contraction?

    <p>Increases the force of contraction</p> Signup and view all the answers

    What is the effect of epinephrine on the heart rate and contractile force?

    <p>Increases heart rate and contractile force</p> Signup and view all the answers

    What is the effect of acetylcholine on the heart rate and contractile force?

    <p>Decreases heart rate and contractile force</p> Signup and view all the answers

    What is the effect of an increase in body temperature on heart rate?

    <p>Increases heart rate</p> Signup and view all the answers

    What is the effect of a high level of potassium ions in the blood plasma on heart rate?

    <p>Decreases heart rate</p> Signup and view all the answers

    What is the primary function of the cardioaccelerator centers in the brain?

    <p>To stimulate cardiac function by regulating heart rate and stroke volume</p> Signup and view all the answers

    What is the effect of sympathetic nervous system activation on the heart?

    <p>Increased heart rate and force of contraction</p> Signup and view all the answers

    Which type of adrenergic receptors predominate in cardiac tissue?

    <p>Beta (β) receptors</p> Signup and view all the answers

    What is the effect of stimulating β2-adrenoceptors in the bronchioles?

    <p>Expansion of bronchioles</p> Signup and view all the answers

    What is the role of α1-adrenoceptors in smooth muscle?

    <p>Contraction of smooth muscle</p> Signup and view all the answers

    What is the effect of stimulating β3-adrenoceptors in adipose tissue?

    <p>Increased lipolysis</p> Signup and view all the answers

    Which of the following is responsible for releasing acetylcholine from postganglionic vagal efferent nerve terminals at the level of the heart SA and AV nodes?

    <p>Postganglionic neurons</p> Signup and view all the answers

    What is the effect of stimulation of the right vagus on the firing rate of the SA node?

    <p>It decreases the firing rate of the SA node</p> Signup and view all the answers

    Which of the following receptors is found in cardiomyocytes and can bind to both acetylcholine and muscarine?

    <p>Muscarinic acetylcholine receptors</p> Signup and view all the answers

    What is the effect of blocking parasympathetic muscarinic acetylcholine receptors on heart rate?

    <p>It increases heart rate</p> Signup and view all the answers

    Which of the following neurotransmitters is released from sympathetic postganglionic nerve terminals and binds to adrenoceptors?

    <p>Norepinephrine</p> Signup and view all the answers

    What is the primary function of the autonomic nervous system in the regulation of cardiac functions?

    <p>To regulate heart rate, contraction force, and velocity</p> Signup and view all the answers

    What is the primary pathway involved in the Goltz reflex that reduces heart rate?

    <p>Receptors in organs → afferent impulse splanchnic nerves → spinal cord → through the medulla oblongata to the nervus vagus → heart</p> Signup and view all the answers

    What is the primary function of the vasomotor center?

    <p>Regulation of vascular tone</p> Signup and view all the answers

    What type of receptors detect changes in blood gases, especially CO2 and H+ ions?

    <p>Chemical receptors</p> Signup and view all the answers

    What is the primary location of the 'pressor area' in the brain?

    <p>Rostral ventrolateral medulla (RVLM)</p> Signup and view all the answers

    What is the effect of anxiety-inducing situations on the circulatory system?

    <p>Increased heart rate</p> Signup and view all the answers

    What is the primary function of the afferent way in the regulation of blood vessels?

    <p>Transmission of signals from blood vessels to the CNS</p> Signup and view all the answers

    What is the effect of an increase in vasomotor tone on blood vessels?

    <p>Constriction and increase in blood pressure</p> Signup and view all the answers

    Which of the following substances is a vasoconstrictor?

    <p>Epinephrine</p> Signup and view all the answers

    What is the primary way that blood pressure is regulated?

    <p>Nervous control of blood vessel diameter</p> Signup and view all the answers

    What is the effect of carbon dioxide on blood vessels?

    <p>It can cause either vasodilation or vasoconstriction</p> Signup and view all the answers

    Which of the following substances is not a vasodilator?

    <p>Norepinephrine</p> Signup and view all the answers

    What is the effect of a decrease in vasomotor tone on blood vessels?

    <p>Dilation and decrease in blood pressure</p> Signup and view all the answers

    What is the role of endothelin in blood vessels?

    <p>Vasoconstriction</p> Signup and view all the answers

    What is the effect of serotonin on blood vessels?

    <p>Vasoconstriction of small blood vessels</p> Signup and view all the answers

    What is the role of Angiotensin in blood vessels?

    <p>Vasoconstriction</p> Signup and view all the answers

    What is the effect of vasopressin on blood vessels?

    <p>Vasoconstriction</p> Signup and view all the answers

    Study Notes

    Classification of Connective Tissue

    • Fluid connective tissue:
      • Blood
      • Lymph
    • Loose connective tissue:
      • Reticular tissue
      • Adipose tissue
      • Pigment tissue
    • Dense connective tissue:
      • Cartilage
      • Bone
      • Skin formations

    Fluid Connective Tissue: Blood

    • Composed of:
      • Blood plasma (liquid part)
      • Blood cells (red blood cells, white blood cells, platelets)
    • Blood functions:
      • WBC - defense function
      • RBC - gas exchange, pH maintenance
      • Platelets - blood clotting (defense function)
      • Plasma - nutrient supply, regulation, transport, etc.

    Blood Functions

    • Transport function:
      • Respiratory gases (O2 and CO2) - respiratory function
      • Biologically active compounds (BAC) - humoral regulation
      • Ensuring metabolism - supply what is needed and take away the end products of metabolism
    • Thermoregulatory function - blood transfers heat, equalizes the temperature between different organs
    • Maintaining homeostasis of the internal environment:
      • Relatively constant concentration of solutes
      • Temperature
      • pH
    • Protective function:
      • Blood contains antibodies, antitoxins, and other substances
      • Immune cells and phagocytes provide humoral and cellular immunity
      • Blood's ability to clot reduces the chance of bleeding

    Blood Volume

    • In animals, blood makes up 8-9% of the body weight
    • Exact blood volume in ml/kg body weight varies

    Blood Depot Organs

    • Liver - up to 20%
    • Spleen - 10-16%
    • Skin (capillaries, veins) - about 10%
    • Veins of pulmonary circulation

    Blood Components and Formation

    • Formed in the central hematopoietic organs:
      • Red bone marrow
      • Thymus
      • Peripheral organs: lymph nodes, intestinal lymphoid follicles
    • Broken down in the spleen and liver
    • Blood consists of:
      • Blood plasma (~60%)
      • Formed elements (blood cells)

    Blood Plasma

    • Straw-colored liquid consisting of organic and inorganic substances
    • Functions:
      • Colloid osmotic (oncotic) pressure
      • pH level maintenance
      • Transport of substances
      • Regulating water exchange

    Blood Plasma Proteins

    • Functions:
      • Protein reserve
      • Supply of nutrients for the body's plastic and energetic processes
      • Colloid osmotic (oncotic) pressure
      • Protective role
      • Help maintain relatively constant blood pH

    Red Blood Cells (RBCs)

    • RBCs are disc-shaped cells with a flatter, concave center, and no nuclei (except in birds).
    • They contain hemoglobin, which consists of Fe and heme, giving RBCs their red color and binding oxygen.
    • RBCs perform a gas exchange function and help maintain pH levels.
    • RBC count per 1 mm3:
      • Horses: 8 million
      • Cows: 6 million
      • Goats: 14 million
      • Pigs: 6-8 million
      • Dogs, cats: 6-7 million
      • Humans (females): 3-4 million, (males): 4.5 million

    Erythropoiesis

    • Erythropoiesis is the process of producing new erythrocytes, taking about 7 days.
    • Erythrocytes are continuously produced in the red bone marrow of large bones.
    • RBCs differentiate from erythrotropietic bone marrow cells, a type of hemopoietic stem cell found in bone marrow.
    • Erythropoiesis is stimulated by:
      • Decreased partial pressure of oxygen (pO2) in blood plasma
      • Erythropoietin (EPO) production in the kidneys
      • Androgens (male gonads, male sex hormones), thyroxine (thyroid gland, T4)
      • Somatotropic hormone (adenohypophysis, growth hormone, STH)

    Regulation of Erythropoiesis

    • Humoral regulation: promoted by thyroxine, corticotropin, glucocorticoids, and androgenic hormones; inhibited by estrogenic hormones
    • Neural regulation: sympathetic nerves stimulate EPO production, parasympathetic nerves stimulate anti-erythropoietin production

    Physiological Hemolysis

    • Mainly occurs in the spleen, but also in the liver and red bone marrow
    • Damaged RBCs are recognized by macrophages and phagocytized in the spleen
    • Hemoglobin is released as a result of physiological hemolysis
    • Macrophages break down hemoglobin into:
      • Globin (heme protein)
      • Heme (pigment part), converted to biliverdin and then bilirubin

    Leukocytes (WBCs)

    • Leukocytes are round cells of various sizes with nuclei
    • Perform protective functions in the body:
      • Phagocytosis (enclose and destroy foreign substances)
      • Forming inflammation against foreign substances
      • Producing specific and non-specific antibodies
      • Degrading, neutralizing, and eliminating toxins of protein origin

    Leukopoiesis

    • Leukopoiesis is a form of hematopoiesis that forms white blood cells (WBC, or leukocytes)
    • Occurs in bone marrow located in bones in adults and hematopoietic organs in the fetus
    • White blood cells are formed from the differentiation of hematopoietic stem cells

    Platelets (Thrombocytes)

    • Platelets are formed in the red bone marrow
    • When coming into contact with an uneven surface, platelets break down and release biologically active substances
    • Platelets form a white thrombus that is unstable and does not adhere well to the edges of the wound

    Thrombopoiesis

    • Thrombopoiesis is the process of platelet formation and growth
    • Occurs in the red bone marrow
    • Platelet reserves reside in the spleen and can enter the bloodstream when needed

    Hemostasis and Blood Clotting

    • Hemostasis is a physiological process that stops bleeding at the site of injury
    • The 4 stages of hemostasis are:
      1. Narrowing (vasoconstriction) of blood vessels
      2. Formation of primary platelet plug (hemostatic plug)
      3. Formation of definitive blood plug
      4. Ingrowth of fibrous tissue into a blood clot

    Hemostasis

    • Hemostasis is a process that prevents blood loss from damaged blood vessels
    • It involves three stages:
      • Vascular spasm: narrowing of blood vessels due to damage, causing smooth muscle in the vessel walls to contract and reduce blood flow
      • Formation of primary platelet plug: platelets stick to the edge of the wound and aggregate to form a non-permanent plug
      • Formation of definitive blood plug: fibrin filaments are formed, and blood cells adhere to them, resulting in a stable blood clot

    Blood Circulation

    • Blood circulation is a continuous process that involves the heart and blood vessels
    • There are two circuits: pulmonary and systemic
    • Pulmonary circuit:
      • Low-pressure circuit
      • Gas exchange takes place in the capillaries of the lungs
      • In contact with the external environment
      • Transports blood to and from the lungs
    • Systemic circuit:
      • High-pressure circuit
      • Capillaries exchange nutrients and gases with body cells
      • In contact with the internal environment
      • Transports oxygenated blood to the body and returns deoxygenated blood to the heart

    Blood Flow

    • Blood flow rate: the volume of blood flowing through a blood vessel in a given period of time
    • Linear velocity of blood flow: the distance traveled by one blood particle in one unit of time
    • Factors affecting blood flow:
      • Vascular resistance: determined by blood viscosity, vessel diameter, vessel length, and characteristics of the vascular wall
      • Blood viscosity: affected by formed elements and plasma proteins
      • Vessel diameter: changes in response to neural and chemical signals
      • Vessel length: longer vessels have greater resistance

    Blood Vessels

    • Arteries:
      • Resistance blood vessels
      • Have elastic layers with muscles that change the diameter of the vessel
      • By function, they are resistance blood vessels
    • Capillaries:
      • Metabolic blood vessels
      • Have the thinnest wall, largest total cross-sectional area, and smallest linear velocity
      • Only place where substances are exchanged between blood and intercellular fluid
    • Veins:
      • Capacitance or volume blood vessels
      • Walls are thinner than arteries, containing smooth muscle
      • Regulate blood flow to the heart

    Heart and Circulation

    • The heart performs the function of a pump
    • Right and left ventricles are in series with each other, separated by the pulmonary and systemic circulation
    • Organs are arranged in parallel rather than in series, which means that the blood flow to each organ is independent of the others

    Cardiac Circulation and Heart Function

    • In parallel circulation, the ventricle is divided among the various organs, and a given volume of blood passes through only one organ before entering the venous outflow of the organ.
    • The advantages of parallel circulation include:
      • Maintaining constant blood pressure at the entrance to each organ
      • Enabling independent control of blood flow to each organ
      • Preventing damage to one organ from affecting the entire circulation

    Heartbeat and Pump Function

    • The heartbeat is a result of successive contraction and relaxation of individual parts of the heart:
      • Atrial systole
      • Ventricular systole
      • Total diastole
    • The heart functions as a pressure pump, ejecting blood during ventricular systole, and a suction pump, sucking blood from the veins into the heart after atrial systole.
    • The pump function is provided by:
      • Structures: heart valves and capacity of heart parts
      • Functional properties: of the myocardium (cardiac muscle)

    Cardiac Muscle Properties

    • The myocardium is able to:
      • Conduct excitation (conductivity)
      • Contract (contractility)
      • Respond to stimuli (excitability)
    • The force of contraction depends on the blood supply to the heart and the grade of its distension.
    • The excitability of the heart muscle changes with the phases of the cardiac cycle.

    Phases of the Cardiac Cycle

    • The cardiac cycle consists of:
      • Atrial systole (approx. 0.1 sec)
      • Ventricular systole (approx. 0.3 sec)
      • Total diastole or pause (0.4 sec)
    • During the cardiac cycle, the heart muscle goes through phases of:
      • Absolute refractory period (ARP)
      • Effective refractory period (ERP)
      • Relative refractory period (RRP)
      • Supernormal (supranormal) phase (SNP)
      • Phase 4: Resting phase

    Physiological Properties of the Heart Muscle

    • The heart muscle has:
      • A long absolute refractory period (0.27 seconds)
      • Follows the "all or none" law
      • Automaticity, the ability to contract rhythmically without external stimulation
    • The cardiac conduction system is responsible for the automaticity of the heart muscle.

    Cardiac Conduction System

    • The cardiac conduction system consists of:
      • Sinoatrial (SA) node: generates the action potential (cardiac pacemaker cells)
      • Atrioventricular (AV) node: located in the interatrial septum
      • Bundle of His
      • Left and right bundle branches
      • Purkinje fibers
    • The speed of conduction of excitation in the heart varies in different parts of the heart.

    Cardiac Cycle Phases

    • The cardiac cycle consists of:
      • Ventricular filling (mid-to-late diastole)
      • Atrial contraction
      • Ventricular systole
      • Isovolumetric contraction
      • Ventricular ejection phase
      • Early diastole (isovolumetric relaxation)
      • Late diastole

    Ventricular Volume Indicators

    • Maximum ventricular filling occurs at the end of atrial contraction, known as end diastolic volume (approximately 120 mL in humans).
    • Minimum filling occurs at the end of ventricular systole, known as stroke volume (approximately 70 mL in humans).
    • End systolic volume is the volume of blood in the ventricle at the end of systole (approximately 50 mL).

    Pressure Changes in the Heart Chambers

    • The highest pressure in the human heart is achieved in the left ventricle and aorta during ventricular systole (up to 120 mm Hg).
    • Pressure drops significantly at the beginning of total diastole, falling to 10 mm Hg in the ventricle and 80 mm Hg in the aorta.
    • The aorta maintains a pressure of 80 mm Hg due to its elastic layer with muscles, which contracts and relaxes to change the diameter of the vessel and resist blood flow.

    Valve Functions

    • Ensure blood flow in the circulatory system in only one direction.
    • Contribute to the filling and emptying of the heart cavities, thus maintaining the normal action of the pump.
    • Valves open or close depending on the pressure difference on both sides.

    Electrical Activity in the Heart

    • Atrial systole:
    • Venae cavea and pulmonary veins are closed.
    • Blood from atria cannot get back into veins.
    • Both atria contract together, increasing pressure inside atria, which opens atrioventricular valves.
    • Ventricular systole:
    • Isovolumetric contraction phase:
      • Atrioventricular valves close, and semilunar valves are closed.
      • Ventricles are a closed space full of blood.
    • Blood ejection phase:
      • Semilunar valves open, and blood is ejected into aorta and pulmonary arteries.
      • Blood is sucked into the heart through veins.
    • Total diastole:
    • Atrioventricular valves, venae cavea, and pulmonary veins are open.
    • The heart fills with blood, and all valves close to prevent backflow.

    Cardiac Muscle Cells

    • There are two major types of cardiac muscle cells:
    • Myocardial contractile cells (99%): responsible for contractions that pump blood through the body.
    • Myocardial conducting cells (1%): form the conduction system, initiating and propagating the action potential that triggers contractions.

    Cardiac Conduction System

    • The conduction system is where excitation occurs in the heart and spreads, producing sequential, rhythmic electrical activities in the myocardium, followed by a response – systole.
    • The bundle of His is the only place where the impulse can go from the atria to the ventricles.
    • There is a gradient of automaticity, with different parts of the conduction system having different self-excitation abilities.

    Electrical Activity of the Heart

    • The ECG records the electrical activity of the heart, measuring the potential difference between excited and non-excited areas.
    • A 12-lead ECG is commonly used, with standard leads marked with Roman numerals I, II, and III.
    • ECG waves:
    • P wave: represents atrial depolarization, resulting in atrial contraction.
    • Q, R, S complex: represents ventricular depolarization.
    • T wave: represents the repolarization of the ventricles.

    Respiratory Sinus Arrhythmia

    • Normally, a small, irregular sinus arrhythmia is observed, reflected in the variability of the R-R interval.
    • During expiration, R-R prolongs (parasympathetic nervous system), and heart rate slows down.
    • During inspiration, R-R shortens (sympathetic nervous system), and heart rate increases.

    ECG Information

    • The ECG provides information about the origin of the excitation in the heart (normal sinus rhythm).
    • It allows judgment about cardiac arrhythmias, transmission of excitation in the heart, and anatomical and physiological integrity of the cardiac conduction system.
    • The ECG also provides information about metabolic disorders in the myocardium, such as blood supply disorders (hypoxia, etc.).

    Blood Flow in Blood Vessels

    • Blood flow is determined by the pressure difference between the beginning and end of a vessel, and resistance (R)
    • The formula for blood flow is: Q = (P1 –P2) / R, where Q is the amount of fluid per unit of time, P1 is the pressure at the beginning of the vessel, P2 is the pressure at the end of the vessel, and R is the total resistance
    • The greater the pressure drop (P1-P2) and the lower the resistance, the higher the blood flow volume velocity

    Factors Affecting Resistance

    • Blood viscosity (usually constant, hematocrit dependent)
    • Length of blood vessels (fixed in adults)
    • Peripheral resistance (the most variable, changes physiologically due to changes in capillary diameter)
    • Elastic resistance (physiologically changes with increasing age)
    • Blood vessel diameter (lumen)

    Structure of Blood Vessels

    • Vessels vary in size and structure, mainly due to lumen diameter and wall layers
    • Inner layer (tunica interna) consists of endothelial cells, basal membrane, connective tissue, and internal elastic lamina
    • Middle layer (tunica media) consists of smooth myocytes, and external elastic membrane
    • External layer (tunica externa) consists of loose connective tissue, collagen fibers, fibroblasts, and smooth myocytes

    Changes in Blood Vessel Diameter

    • Passive changes occur due to blood pressure stretching the vessel wall
    • Active changes occur due to smooth myocyte activity
    • Changes in lumen size are used to regulate blood supply to organs and tissues

    Blood Circulation in Blood Vessels

    • The circulatory system provides blood circulation in a closed circuit, formed by the heart and blood vessels
    • The right and left heart pumps maintain circulation in the pulmonary and systemic circuits, respectively
    • The functional unity in the cardiovascular system forms three levels of blood circulation: systemic hemodynamics, blood circulation in organs, and microcirculation

    Systemic Hemodynamics

    • Ensures blood circulation throughout the system (both circuits)
    • Provides cooperation with pulmonary circulation, digestive system, urinary system, endocrine system, and more

    Blood Circulation in Organs

    • Provides blood supply to organs and tissues according to their functional characteristics
    • Cardiac output is distributed differently between organs and tissues
    • Organs have the ability to self-regulate their blood flow regardless of systemic blood pressure and body condition

    Microcirculation

    • Occurs through small blood vessels – capillaries with a diameter of 5-10 micrometers
    • Provides blood supply to tissues and organs at the cellular level

    Regulation of the Action of the Heart

    • Three homeostatic mechanisms ensure adequate blood flow, blood pressure, distribution, and perfusion:
      • Autoregulatory mechanism
      • Humoral mechanism
      • Neural mechanism

    Autoregulatory Mechanism of Regulation

    • Refers to mechanisms contained within the heart itself
    • Regulates heart muscle contraction and relaxation
    • Two types:
      • Frank-Starling mechanism (heterometric autoregulation)
      • Homeometric regulation

    Frank-Starling Mechanism

    • Force of contraction produced by cardiac muscle is related to the degree of stretch of cardiac muscle fibers
    • Venous return determines the degree of stretch
    • Relationship between preload and stroke volume is called Starling's law of the heart
    • Increased afterload increases the workload on the heart and can lead to heart failure

    Homeometric Regulation

    • Does not involve changes in cardiac fiber length
    • Uses intrinsic molecular mechanisms to modulate contractile strength
    • Rate and rhythm effects:
      • Increased heart rate increases peak tension and maximum shortening
      • Temperature affects heart rate (e.g., fever increases heart rate, hypothermia decreases heart rate)

    Humoral Mechanism of Regulation

    • Regulates heart rate and contractile force of the heart muscle
    • Factors that increase heart rate and contractile force:
      • Epinephrine
      • Thyroxin (T4) and triiodothyronine (T3)
      • Calcium ions (high level)
    • Factors that decrease heart rate and contractile force:
      • Acetylcholine
      • Potassium ions (high level)

    Neural Mechanism of Regulation

    • Refers to mechanisms external to the heart, such as neural regulation
    • Regulates heart muscles contraction, velocity, force, and excitability
    • Sympathetic nervous system:
      • Increases heart rate and contractile force
      • Stimulates the release of norepinephrine
    • Parasympathetic nervous system:
      • Decreases heart rate and contractile force
      • Stimulates the release of acetylcholine

    Cardiovascular Centers in the Brain

    • Located in the medulla oblongata
    • Regulate blood pressure and flow
    • Divided into:
      • Cardioaccelerator centers (stimulate cardiac function)
      • Cardioinhibitor centers (slow cardiac function)
      • Vasomotor centers (control vessel tone)

    Sympathetic Nervous System Control of the Heart

    • Sympathetic fibers arise from the thoracic spinal cord
    • Release norepinephrine, which binds to adrenergic receptors on the heart
    • Results in positive chronotropic, inotropic, bathmotropic, and dromotropic effects on the heart

    Parasympathetic Nervous System Control of the Heart

    • Parasympathetic preganglionic cell bodies originate in the brainstem
    • Release acetylcholine, which binds to muscarinic acetylcholine receptors on the heart
    • Results in negative chronotropic, inotropic, and dromotropic effects on the heart

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    Description

    This quiz covers the classification of connective tissue, including fluid, loose, and dense connective tissue, and their components, in the context of the cardiovascular system. Topics include blood, lymph, reticular tissue, adipose tissue, and more.

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