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BIO172 Exam Latest Update Questions and Verified
Answers
Two major divisions of the cardiovascular system - ANSWER Pulmonary Circuit and Systemic Circuit Pulmonary Circuit - ANSWER Right side of the heart. Carries blood to lungs for gas exchange. Recieves blood that has circulated through body and pumps to pulmonary trunk, returns to heart via pulmonary veins. Systemic Circuit - ANSWER Left side of heart. Supplies oxygenated blood to all tissues of the body. Recieves blood from pulmonary veins and pumps to the aorta. Where is the heart located? - ANSWER Mediastinum T/F: Main functions of the cardiovascular system include the transport and exchange of respiratory gases, nutrients, and wastes throughout the body. - ANSWER True Pericardium - ANSWER Double-layered membrane surrounding the heart Pericardial Sac - ANSWER Outer wall of pericardium. Fibrous layer of dense irregular connective tissue and deep serous layer. Pericardial Cavity - ANSWER Between parietal and visceral layers, contains pericardial fluid that reduces friction between the two membranes. Three Layers of Heart Wall - ANSWER Epicardium, myocardium, and endocardium. Epicardium - ANSWER Serous membrane on heart surface. Largest branches of coronary blood vessels travel here.
Myocardium - ANSWER Thickest, middle layer of cardiac wall. Consisting mainly of cardiac muscle. Endocardium - ANSWER Simple squamous epithelium that lines the heart chamber, innermost layer. Covers valve surfaces and is continous with endothelium of blood vessels. Syncytium - ANSWER A mass of cells that function as a unit. Atrial and ventricular networks in the heart. Fibers within network are connected by intercalated discs. Cardiac Muscle Fiber vs. Skeletal Muscle Fiber - ANSWER - Shorter in length
- Larger in diamter
- Square shaped rather than circular
- Less sarcoplasmic reticulum
- Require Ca+2 from extracellular fluid for contraction
- Longer refractory period
- Contains more mitochondria
- Contractions last 10 to 15 times longer T/F: Cardiac muscle has more mitochondria and depends less on a continual supply of oxygen than does skeletal muscle. - ANSWER False When do cardiac muscle cells contract? - ANSWER Stimulated by their own autorhythmic fibers Fibrous Skeleton - ANSWER Framework of heart made up of collagenous and elastic fibers Functions of Fibrous Skeleton - ANSWER - Provides structural support
- Anchors cardiac muscle cells
- AV Valves contain chordae tendineae that connect valve cusps to conical papillary muscles on floor of ventricles. Prevent AV Valves from flipping inside out.
- Semilunar Valves regulate flow of blood from ventricles into the great arteries. T/F: As pressure in the aorta rises due to atherosclerosis, more ventricular pressure is required to open the aortic valve. - ANSWER True Pathway of Blood Through Heart - ANSWER 1. Blood enters right atrium from superior and inferior vena cava.
- Blood in right atrium flows through right AV valve into right ventricle.
- Contraction of right ventricle forces pulmonary valve open.
- Blood flows through pulmonary valve into pulmonary trunk.
- Blood distributed to lungs via right and left pulmonary arteries. Unloads CO2 and loads O2.
- Blood returns from lungs via pulmonary veins to left atrium.
- Blood in left atrium flows through left AV valve into left ventricle.
- Contraction of left ventricle forces aortic valve open.
- Blood flows through aortic valve into ascending aorta.
- Blood in aorta is distributed to organs in body. Unloads O2 and loads CO2.
- Blood returns to heart via vena cava. Coronary Circulation - ANSWER Delivers oxygenated blood and nutrients to myocardium, removes carbon dioxide and wastes. Left Coronary Artery - ANSWER Travels through coronary sulcus under left auricle and divides into two branches (Anterior Interventricular & Circumflex). Anterior Interventricular Branch (LAD) - ANSWER Also known as Left Anterior Descending Artery (LAD). Travels down anterior interventricular sulcus to apex and to posterior side of heart. Supplies both ventricles and anterior 2/3 of interventricular septum.
Circumflex Branch - ANSWER Continues around left side of heart into coronary sulcus, gives off left marginal branch. Furnishes blood to left ventricle. Ends on posterior side of heart, supplies blood to left atrium and posterior wall of left ventricle. Right Coronary Artery - ANSWER Supplies right atrium and sinoatrial node. Travels through coronary sulcus under right auricle and gives off two branches (Right Marginal & Posterior Interventricular). Right Marginal Branch - ANSWER Runs towards apex of heart, supplies lateral aspect of right atrium and ventricle. Posterior Interventricular Branch - ANSWER In 4/5 of the population, supplies walls of both ventricles. What does the posterior interventricular artery branch off of in 80% of the population? - ANSWER Right coronary artery T/F: RCA ends by joining Anterior Interventricular Branch of LCA. - ANSWER True Coronary Sinus - ANSWER Transverse vein in coronary sulcus on posterior side of heart. Collects blood from all other coronary vein sources, empties into right atrium. T/F: In most organs blood flow peaks when ventricles contract and eject blood into arteries, diminishing when ventricles relax. - ANSWER True What happens during ventricular contraction? - ANSWER The semilunar valves open and the AV valves close. T/F: Blood flow descreases in coronary arteries during ventricular relaxation. - ANSWER False
Bypass Surgery - ANSWER Section of leg vein is removed, one end of the vein being attached to the aorta and the other to a coronary artery. Obstructed region is bypassed, the grafted vein providing a pathway through which blood can flow. Heartbeat - ANSWER Coordinated by cardiac conduction system. Conduction fibers initiate and distribute impulses throughout myocardium. Sinoatrial (SA) Node - ANSWER - Modified cardiac cells in the right atrium, initiate each heartbeat and determines heart rate.
- Referred to as the primary pacemaker.
- Fires 90-100 x/min T/F: Sinus rhythm, triggered by SA node, is a cycle of 70-80 bpm in adults. - ANSWER True Although rates of 60-100 bpm are not unusual Sinus Node Arrhythmias - ANSWER Bradycardia, Tachycardia, and Sinus Arrest. Bradycardia - ANSWER Slow heart rate (<60 bpm) Tachycardia - ANSWER Fast heart rate (>100 bpm) Sinus Arrest - ANSWER SA node doesn't fire and other pacemaker (AV node) is forced to take over. Atrioventricular (AV) Node - ANSWER - Located near right AV valve at lower end of interatrial septum.
- Acts as an electrical gateway to ventricles.
- Activated by AP's from SA node.
- Fires 40-60 x/min Bundle of His - ANSWER Atrioventricular bundle, pathway by which signals leave the AV node. Fires 30-40 x/min. Purkinje Fibers - ANSWER Nervelike processes spread throughout ventricular myocardium that distribute electrical excitation to cardiocytes. Fires 30-40 x/min. Sympathetic Stimulation - ANSWER Increases heart rate and contraction strength, dilates coronary arteries. Can raise HR as high as 230 bpm. Parasympathetic Stimulation - ANSWER Reduces heart rate, can slow HR to as slow as 20 bmp or even stop it for a few seconds. What stimuli can cause other parts of the conduction system to fire before SA node does? - ANSWER Hypoxia, electrolyte imbalances, caffeine, nicotine, other drugs, etc. Electrocardiogram (ECG) - ANSWER Recording of the electrical changes that occur in the myocardium during a cardiac cycle What does ECG help to determine? - ANSWER If conduction pathway is abnormal, if the heart is enlarged, and if certain regions are damaged. Deflection/Waves of ECG - ANSWER P wave, QRS wave, and T wave. P Wave - ANSWER Atrial depolarization QRS Complex (3 Waves) - ANSWER Ventricular depolarization produced when signal from AV node spreads through ventricular myocardium. Complex consists of a small downward deflection (Q), a tall sharp peak (R), and a final downwards deflection (S).
S2 - ANSWER Softer and sharper, described as dubb. Occurs during ventricular diastole when pulmonary and aortic semilunar valves are closing. Murmur - ANSWER Abnormal heart sound caused by cusps not completely closing Cardiac Output - ANSWER Volume of blood ejected by each ventricle each minute. Equals the SV multiplied by the HR. Stroke Volume (SV) - ANSWER Volume of blood ejected by the ventricle with each contraction Heart Rate (HR) - ANSWER Number of beats per minute What does slower heart rate mean in terms of cardiac output? - ANSWER Slower heart rate increases end diastolic volume, stroke volume, and force of contraction. Regulation of Stroke Volume - ANSWER 1. Preload
- Contractility
- Afterload Preload - ANSWER Effect of stretching, amount of tension in the ventricular myocardium immediately before it begins to contract. Myocardial Contractility - ANSWER The ability of the heart muscle to contract at any given period. Afterload - ANSWER The pressure that must be overcome before a semilunar valve can open. Opposes the opening of valves and therefore limits stroke volume.
Peripheral Resistance - ANSWER Hypertension which increases afterload and opposes ventricular ejection. What is the body's principal mechanism of short term control over cardiac output and blood pressure? - ANSWER Changing heart rate Autonomic Regulation of Heart - ANSWER a. Nervous control of the cardiovascular system stems from cardiovascular center in medulla oblongata. b. Sympathetic impulses increase heart rate and force of contraction. c. Parasympathetic vagus nerves have cholinergic, inhibitory effects on SA and AV nodes. Decrease heart rate. d. With intact innervation, resting heart rate is held down to about 70-80 bpm by vagal tone. Vagal Tone - ANSWER Background firing rate of vagus nerves Vagal tone refers to what? - ANSWER Decreasing of the heart rate below its inherent rhythm by parasympathetic stimulation Chemical Regulation of Heart - ANSWER a. Heart rate increased by epinephrine and norepinephrine. b. Nicotine accelerates the heart by stimulating catecholamine secretion. c. Caffeine and related stimulants in tea and chocolate inhibit cAMP breakdown, prolonging adrenergic effects. d. Ions also affect heart rate. The electrolyte with the greatest effect on the heart is potassium. e. Other factors such as age, gender, physical fitness, and temperature affect heart rate. T/F: Sustained exercise decreases oxygen demand in muscles. - ANSWER True T/F: Exercise makes the heart work harder, and this decreases cardiac output. - ANSWER False
Capillaries branch to form what? - ANSWER An exstensive capillary network throughout the tissue. This increases the surface area and allows for rapid exchange of large quantities of materials. T/F: A vasodilator causes a decrease in local blood flow at a capillary bed. - ANSWER False Types of Capillaries - ANSWER Continuous, Fenestrated, and Sinusoids. Continuous Capillaries - ANSWER - Occur in most tissues
- Cells seperated by intercellular clefts through which small solutes can pass.
- Lack intercellular clefts in the brain and instead form the blood brain barrier. Fenestrated Capillaries - ANSWER - Have endothelial cells riddled with patches of filtration pores
- Allow for rapid passage of small molecules
- Retain most proteins and larger particles
- Important in organs that engage in rapid absorption or filtration. Includes kidneys, endocrine glands, small intestine, etc. Sinusoids (Discontinuous Capillaries) - ANSWER Irregular blood filled spaces in the liver, bone marrow, and spleen. Cells are seperated by wide gaps with no basal lamina and large fenestrations, meaning even proteins and blood cells can pass through. This is how proteins synthesized by the liver enter the blood. What is the most common type of blood capillary? - ANSWER Continuous capillary T/F: When the precapillary sphincters are open, the capillaries are well perfused with blood. When they're closed, blood bypasses capillaries and flows through the thoroughfare channel. - ANSWER True
How much of the body's capillaries are shut down at any given time? - ANSWER About three quarters. Due to there not being enough blood to fill the entire vascular system at once. How much of the blood is in the capillaries at any given time? - ANSWER 250-300 mL (5%) Capillary Exchange - ANSWER Two way movement of fluid across capillary walls. At arterial end, blood pressure forces fluid out of the capillary to fill surrounding tissue cells. At venous end, fluid is drawn back into capillary by osmotic pressure. T/F: Blood flow is slow in capillaries. - ANSWER True 3 Routes That Chemicals Pass Through Capillary Walls - ANSWER 1. Transcytosis through the endothelial cell cytoplasm.
- Diffusion and reabsorption through intercellular clefts between endothelial cells.
- Filtration pores in fenestrated capillaries. What is the most important method of capillary exchange? - ANSWER Simple diffusion Simple diffusion - ANSWER - Substances like O2, CO2, glucose, amino acids, antibodies, lipids, hormones, and metabolic wastes diffuse down concentration gradients.
- Lipid soluble substances such as steroid hormones and O2 diffuse through plasma membranes. Insoluble lipids like glucose and electrolytes must pass through channels, filtration pores, or intercellular clefts.
- All plasma solutes pass freely across most capillary walls. Prime exception of water soluble materials across capillaries is the blood brain barrier. Transcytosis - ANSWER Process in which endothelial cells pick up material on one side of the plasma membrane by pinocytosis or receptor-mediated endocytosis, transport the vesicles across the cell, and discharge the material on the other side by exocytosis.
What is blood colloid osmotic pressure largely due to? - ANSWER The proteins in the blood, and it promotes reabsorption. Venules - ANSWER Receive blood from capillaries Veins - ANSWER Carry blood toward the atria of heart What is considered the capacitance vessels of the cardiovascular system? - ANSWER Veins At rest, how much of the blood is found in systemic veins? Systemic Arteries? - ANSWER 64% in veins and 13% in arteries T/F: Veins are subjected to relatively high blood pressure due to distance from ventricles. - ANSWER False Veins are subjected to relatively LOW blood pressure. T/F: Veins collapse when empty and maintaine flattened, irregular shapes in tissue sections. - ANSWER True Valves in veins cause what? - ANSWER Venous blood flow to go in only one direction Venous Valves - ANSWER Keep blood moving upward toward heart rather than dropping down again when muscles relax. Most abundant veins in limbs. Skeletal Muscle Pump - ANSWER Contraction of muscles surrounding vein forces blood through the valves and back toward heart Weak venous valves can lead to what? - ANSWER Varicose veins
Vascular (Venous) Sinuses - ANSWER Veins with very think walls with no smooth muscle to alter diameters. Example is coronary sinus of heart. Most Common Circulatory Route of Blood Flow - ANSWER Heart → Arteries → Capillaries → Veins → Heart Exceptions are portal systems and anastomoses. Portal System - ANSWER Blood flows through two consecutive capillary networks before returning to the heart Anastomoses - ANSWER Point where two blood vessels merge Arterial Anastomoses - ANSWER Point where two arteries merge Layers of Blood Vessels - ANSWER Tunica Interna, Tunica Media, and Tunica Externa. Tunica Interna - ANSWER - Lines the inside of the vessel
- Direct contact with blood
- Continous with endocardium
- Consists of simple squamous endothelium
- Secretes chemicals that stimulate vessel dilation
- Repels blood cells and platelets Tunica Media - ANSWER Consists of smooth muscle and elastic fibers that provide for changes in lumen diameter
Vasodilation - ANSWER Widening of blood vessels. Occurs as result of relaxation of smooth muscle in tunica media. What is blood viscosity determined by? - ANSWER RBC count and albumin concentration T/F: The farther blood travels through a vessel, the more cumulative friction it encounters, so pressure and flow decline with distance. - ANSWER True Systemic Vascular Resistance - ANSWER Refers to all vascular resistances offered by systemic blood vessels. Most resistance in arterioles, capillaries, and venules due to small diameters. Syncope - ANSWER Sudden and typically temporary loss of consciousness followed by spontaneous recovery What 3 mechanisms can control blood pressure and flow? - ANSWER Local, Neural, and Hormonal Neural Regulation of BP - ANSWER One of two things occurs:
- Baroreceptors stretch and send message to medulla which slows HR and dilates arteries.
- Baroreceptor inactivity sends message to medulla which speeds HR and constricts arteries. Cardiac Sinus Reflex - ANSWER Concerned with maintaining normal blood pressure in brain. Initiated by baroreceptors in the wall of the carotid sinus. Aortic Reflex - ANSWER Concerned with general systemic blood pressure. Initiated by baroreceptors in the wall of the arch of the aorta or attached to the arch. Cardiovascular Center (CV) - ANSWER Group of neurons in the medulla that regulate HR, contractility, and blood vessel diameter.
Where does the cardiovascular center receive input from? - ANSWER Higher brain regions and sensory receptors Output from CV flows along what? - ANSWER Sympathetic and parasympathetic fibers Hormonal Regulation of BP - ANSWER - Angiotensin raises BP.
- Aldosterone promotes Na+ retention by kidneys. This retention promotes higher BV and BP.
- Antidiuretic hormone promotes water retention, which raises BP.
- Epinephrine and norepinephrine bind to adrenergic receptors, stimulating vasoconstriction. Local Autoregulation of BP - ANSWER Refers to the ability of tissue to automatically adjust its own blood flow to match metabolic demand for O2 supply and nutrients, as well as removal of wastes. Oxygen is the principal stimulus. What do platelets, basophils, and endothelial cells secrete that stimulate vasodilation? - ANSWER Histamine, bradykinin, nitric oxide, and prostaglandins. Other chemicals like serotonin cause vasoconstriction. Angiogenesis - ANSWER Formation of new blood vessels Pulse - ANSWER Pressure wave of blood with each beat of left ventricle What artery is most commonly used to feel pulse? - ANSWER Radial Pressure Points - ANSWER Sites where pressure is applied to stop bloow flow with hemorrhage What is used to measure BP? - ANSWER Sphygmomanometer Systolic Pressure (SBP) - ANSWER Peak arterial BP attained during ventricular contraction
