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Circulatory Guide ?s

Cardio/Pulmonary Circulation System Guide Questions

Distinguish between the pulmonary and systemic circulatory system in terms of purpose, ventricles, arteries leaving these ventricles and whether or not these vessels are carrying oxygenated or deoxygenated blood. Pulmonary: Purpose: send deoxygenating blood to lungs or oxygenation; Ventricle: Right; Artery: Pulmonary—carrying deoxygenated blood. Systemic: Purpose: pump oxygenated blood to all of the body; Ventricle: left; Artery: Aorta—carrying oxygenated b
What is the importance in realizing that the two circulatory systems are serially connected in terms of cardiac output? CO of R vent (pulm circ) becomes input to the L vent. CO of the L ventricle inputs to R vent. If vents don't pump same amt of blood/minute blood backs up behind inefficient vent causing pulm edema (inefficient L vent) or syst edema (inefficient R vent)
What are the two functions of the pericardium? 1. Prevent displacement of the heart during gravitational acceleration and deceleration; 2. Act as a physical barrier that protects the heart against infection and inflammation from the surrounding organs and tissues within the chest cavity.
The two layers/membranes of the pericardium? Parietal & Visceral
What is the relationship between the pericardial cavity and the serous membranes of the visceral and parietal pericardium? What is the function of the pericardial cavity? Both the visceral and parietal serous membranes secrete a serous fluid that collects in the pericardial cavity. The serous fluid acts as a lubricant, allowing the visceral and parietal pericardium to freely side over one another with each heartbeat.
The thickness of the myocardium of the four chambers of the heart is dependent on what? Thickness of the myocardium in each of the chambers (R & L atrium, R & L ventricle) is dependent on the blood pressure that the chamber is pumping against, with the thickest walls being in the chambers that pump blood against the highest pressure.
Why, then, is the left ventricle thicker than the right? The wall of the left ventricle is the thickest of all the chambers because it pushes blood into the aorta against a mean aortic blood pressure of 60-120 mm Hg.
What is the composition of the endocardium? What important structures of the heart are formed by the endocardium? The endocardium is composed of connective tissue over which lies a thin layer of cells called the endothelium, composed of endothelial cell; The atrioventricular valves, pulmonic valves, and the aortic valves.
What is the main component of the fibrocollagenous skeleton of the heart? What is the function of this component? Central fibrous body; Central fibrous body (1)forms valve rings which support the base of the A/V, pulmonic, and aortic valves; and (2) provide a “skeleton” (a fibrocollagenous skeleton) to which the muscles of the heart “originate” and “insert”.
The downward extension of the fibrocollagenous tissue forms what? Is this a minor or major component of the interventricular septum? What is the other component? Membranous interventricular septum; Minor; Muscular interventricular septum.
What is the importance in the fact that the fibrocollagenous skeleton of the heart separates the atrial syncytium from the ventricular syncytium in relationship to electrical impulses? Fibrocollagenous skel of heart separates atrial (network of cardiac mm connected by intercalated discs) & ventricular syncytium; elec impulse from former must pass through special tissue called AV node before triggering latter. SA node controls HR/rhythm.
What are the the atrioventricular valves? Semilunar valves? The atrioventricular (AV) valves consist of the tricuspid (right) valves and bicuspid or mitral (left) valves; The semilunar valves consist of the pulmonic valves and the aortic valves
Which are open and which are closed during the ventricular diastole? Isovolumic contraction? During ventricular diastole (relaxation) the AV valves are open and the semilunar valves are closed; During isovolumic contraction both the AV valves and the semilunar valves are closed
Ventricular Systole? Isovolumic relaxation? During ventricular systole, the AV valves are closed and the semilunar valves are open; During isovolumic relaxation, the AV valves and the semilunar valves are closed.
During systole, are the chordae tendineae of the atrioventricular valves slack or taut? During systole, because the atrioventricular valves are closed, the chordae tendineae is taut.
During diastole, are the papillary muscles relaxed or contracted? During diastole, the papillary muscles of the atrioventricular valves are slack because the valves are open.
What are the three veins entering the right atrium? The superior vena cava, the inferior vena cava, and the coronary sinus
Using the answers to question 13 (Superior & Inferior VC, Coronary Sinus), at rest, which one of those veins would be carrying the least amount of oxygen (i.e., more oxygen has been extracted)? At rest, all body tissues except cardiac mm extracts ~25% of O2 supplied by arteries. Blood entering the right atria from the superior/inferior VC, is still carrying about 75% saturated with O2. At rest myocardium extracts about 90% of O2 supplied it.
Above Answer Continued... Blood to R atria from coronary sinus is ~10% saturated with O2. When heart increases O2 demand (its rate & strength at which it contracts) the major way it can meet this O2 demand is to increase coronary blood flow. Deleterious effect of atherosclerosis.
The second sound of the heart is heard at the beginning of this phase Isovolumic Ventricular Relaxation
This is the midportion of diastole prior to atrial systole when both the atrial & ventricular chambers are relaxed Diastasis
When pressure in the ventricles falls below that of the atria, the AV valves open & ventricular filling begins Rapid Ventricular Filling
A/V valves are open & semilunar valves are closed while the pressure in the atria is rising Atrial Contraction
A/V valves & semilunar valves are closed & the pressure in the ventricles is rising Isovolumic Ventricular Contraction
Stroke volume is pushed into the aorta Ventricular Ejection
At the beginning of this phase, the fist sound of the heart (S1) is heart Isovolumic Ventricular Contraction
A/V valves & semilunar valves are closed & the pressure in the ventricles are falling Isovolumic Ventricular Relaxation
The first sound of the heart is caused by what? The second sound? First sound of the heart mostly caused by the closing of AV valves; The second sound of the heart is the combination of the closure sounds of aortic and pulmonic valves.
Why is the internodal pathway richly innervated by the autonomic NS? Parasympathetic (Vagal) and sympathetic fibers are able to control the heart rate and the speed at which the action potential travels through the intermodal pathway.
Why is the impulse delayed for 0.1 seconds at the AV node? This allows the left and right atria to complete atrial systole, pushing most of the it’s blood into the ventricles.
What areas of the ventricles do the 3 bundle branches innervate? RBB innervates walls of the R ventricle; the left posterior fascicle innervates the posterior wall of the left ventricle; and the left anterior fascicle innervates the anterior wall of the left ventricle as well as the muscular interventricular septum.
What is the function of the Purkinje fibers, where are they located, and what is the importance of that arrangement when considering the direction that the ventricles contract Fxn of Purkinje fibers: stimulate groups of myocardial cells so electrical activity spread thru vents; Purkinje fibers located at end of bundle branches; Anatomical arrangement: depol of ventricles begin at bottom, contract up & out pulmonary artery/aor
When considering the electrocardiogram (ECG), what does the following represent: P wave, QRS complex, and T wave? What would abnormal ST segments suggest? P wave: atrial depol; QRS complex: ventricular depol; T wave: ECG representation of ventricular repol; ST segment: elevated or depressed if heart lacks O2.
To which areas of the heart does the right coronary artery distribute blood? The right coronary artery is distributed to the right atrium, right ventricle, and variable portions of the inter-ventricular septum and left ventricle.
What are the major branches of the left coronary artery? To which areas of the heart does the anterior coronary artery distribute blood? The circumflex artery? Left ant descending a. and circumflex a.; Left ant descending a. supplies blood to the anterior wall of the left ventricle and variable portions of the inter-ventricular septum; Circumflex a. supplies blood to the lateral & posterior wall of the left ve
What is the importance of coronary collateral circulation? Coronary collaterals vessels can be thought of as the heart's 'back-up system' as they are essentially invisible until activated, when they can enlarge their diameters in order to carry significant blood flow and bypass blockages
What determines whether the left or right coronary artery is the dominant artery? Artery supplying PDA determines dominance. If PDA supplied by R coronary a: coronary circ is “R-dominant”. PDA supplied by circumflex a: coronary circ is “L-dominant”. If PDA supplied by right coronary a and circumflex a: coronary circ is “co-dominant”
Which is the neurotransmitter released by pre-ganglionic parasympathetic nerves? Sympathetic nerves? ACh & ACh
Which is the receptor on the postganglionic nerve of the parasympathetic NS? Sympathetic NS? Nicotinic & Nicotinic
Which is the neurotransmitter of the postganglionic parasympathetic NS? Sympathetic NS. ACh & Norepi
Which is the receptor on the heart that is stimulated by the vagal nerve? Sympatheitc nerve? Muscarinic & Beta-1
Increase or decrease in innervation/stimulation of the heart by the sympathetic NS has what affect on the heart in terms of heart rate and contractility? By the vagal nerve? Increase in symp stim of heart: increased HR & contractility. Decrease in symp stim: opposite. Increase in vagal tone: same as increase in parasymp innervations/stim of heart & only affects HR (no effect on contractility); oppo effect on HR as symp stim
Above answer continued... An increase in parasympathetic innervations/stimulation of the heart will cause a decrease in heart rate whereas a decrease in parasympathetic innervations causes an increase in heart rate
What is preload? Preload is the volume of blood (in milliliters) that fills the ventricles during diastole;
What is afterload? Afterload as the resistance to ejection of blood during systole. The main resistance to ejection is either pulmonary arterial (for right ventricle) or aortic (for left ventricle) blood pressure;
What is cardiac output? Cardiac output (Q) is the product of HR and SV (Q = HR x SV).
Given a HR of 110 beats per minute (bpm) and a SV of 95 ml, what is the cardiac output? 110 x 95 = 10,450 ml/min or 10.45 liters/min.
What is the relationship between pre-load and the Frank-Starling law of the heart? Frank-Starling law of the heart states that the more the ventricle is filled with blood during diastole or preload the greater the volume of ejected blood will be during the resulting systolic contraction (stroke volume)
Length of cardiac muscle sarcomeres & relationship to preload force generated by a single muscle fiber is proportional to the sarcomere length. As preload increase, the sarcomere length increases,and the force produced by each cardiac muscle increases.
Where is the tunica intima located and what is it composed of? Tunica media? The tunica intima, which is the inner layer of a blood vessel, is composed of the endothelium and associated connective tissue of the basal lamina; Tunica media formed by a layer of circumferential smooth muscle and variable amounts of connective tissue;
Tunica adventitia? Where are the elastic lamina located? The tunica adventitia, which consists mainly of connective tissue fibers. Most muscular aa have 2 elastic lamina—internal and external. Internal is b/t tunica intima & tunica media. External is located b/t tunica media & tunica adventitia.
Give examples of elastic arteries? What is the predominant anatomical characteristic of elastic arteries? Examples: aorta, innominate, iliac, subclavian aa; Elastic arteries: thick, highly developed media of which elastic fibers are the main component. These are gathered together in sheets arranged in concentric layers throughout the thickness of the media
Explain how this characteristic is necessary for these vessels to carry out their functional role (include in this answer an explanation of their functional role). At end of L vent contraction elastic fibers in aorta return to “unstretched” state during diastole, maintains diastolic pressure in aorta/large aa of ~60-80. This smooths the expulsion of blood from Left vent into steady flow thru arterial system.
What is the vasa vasorum, where is it found, and what is its function? vasa vasorum (Latin, "the vessels of the vessels") is a network of small blood vessels found in the tunica adventitia and function to supply nutrients to the cells in the lamina of large blood vessels.
Anatomically, what is the main difference between elastic and muscular arteries? Muscular arteries have a tunica media composed almost entirely of smooth muscle leaving two layers of elastic lamina, the internal and external elastic lamina.
Explain the relationship between postganglionic sympathetic nerves, norepinephrine, alpha-1 and alpha-2 receptors, and the diameter of muscular arteries. Postganglionic sympathetic nerves, which run along the length of muscular arteries, release norepinephrine which stimulate the α1-adrenoceptors and α2-adrenoceptors on the smooth muscle cells making up the tunica media, causing vasoconstriction.
Describe the components of the wall of a medium size artery and what happens to those components as the arterioles get smaller and become a small arteriole. Medium size artery has well defined tunica int, med, and adv, & distinct int/ext elastic lamina. As aa get smaller following occurs: Elastic lamina lost; Smooth mm in tunica media become discontinuous; Adventitia of arterioles is insignificant
Where are pre capillary sphincters located, what are they composed of, and what are their function? Pre capillary sphincters are specialized regions near the junction between the terminal (smallest) arterioles and the capillaries; consist of a few smooth muscle cells arranged circularly
What happens to the speed of the flow of blood through the circulatory system as it goes from aorta to capillaries? Why? As blood goes from capillaries to the vena cava? Why? Blood velocity decreases from aorta to capillaries; Total cross sectional area increases from aorta to capillary. Same amount of blood must pass through larger area, speed of flow slower; Velocity increases from capillary to VC bc of same principle.
What are the two mechanisms that control the radius of the arterioles and the pre capillary sphincters and, therefore, the amount of blood entering a capillary network. Neural vasoconstrictor activity (i.e., via postganglionic sympathetic nerves) and locally derived vasoactive substances.(i.e., metabolic vasodilation).
Where are pericytes located & what is their function? Pericytes: contractile cells embedded in the basement membrane, wrap around the endothelial cells of capillaries throughout the body. They play an important role in the blood-brain barrier and in the formation of new blood vessels (i.e. angiogenesis).
These are present in the liver and spleen where greater movement of cells and materials are necessary. Discontinuous
The endothelial cells are pierced by pores which extend through its full thickness and provide channels across the capillary wall. Fenestrated
The most common type of capillary found throughout the body Continuous
Plays a major role kidney filtration. Fenestrated
These capillaries are more irregularly shaped with wide gaps between the endothelial cells and there may be partial or complete absence of the basal lamina. Discontinuous
The endothelial cells form a continuous internal lining without any intercellular or intracytoplasmic defects. Continuous
Compare blood pressure in the veins to that in the arteries BP in venous circulation remains <25; BP on the arterial side remains >25. Pressure on arterial side is remains high enough to “push” blood to capillaries. Pressure on the venous side needs “help” to return the blood from the capillaries to the heart
How many layers make up the walls of veins? Which layer forms the valves? Veins have three layers: tunica intima, media, and adventitia. However, in the veins, these layers are much less developed; Valves: formed by internal folds of endothelial lining. Ensure venous blood flow goes 1 direction—towards the heart
Why are veins called "capacity vessels"? At rest, a major part of the blood volume, approximately 60%, is contained within the venous system. Therefore, as we become more active and need more blood, we “tap into” this “pool” of blood
What are three main processes that maintain venous return to the heart? Increase in venomotor tone; Skeletal muscle pump; Respiratory pump
What controls venomotor tone? How does venomotor tone differ from vasoconstriction on the arterial side? Sympathetic innervation; Due to thin tunica media, stimulation of alpha receptors on the smooth muscles in the walls of veins results in increase rigidity with some vasoconstriction.
What affect does bed rest have on venomotor tone and why is this of clinical importance? Long bed rest reduces venomotor tone & method of returning blood to heart is reduced. After bed rest (24-73 hrs), stand & walk unassisted: “ortho hypo”, light headedness & probability for debilitating falls. Tx: periodic assisted standing & slow walking
What characteristic of the veins of the lower legs and arms assists the skeletal muscle pump in returning blood toward the heart? One-way valves
When I was in the Army I spent many hours at parade rest. Why did I slowly rock back and forth on my feet and push up and down on my toes during these wonderful productive hours (HA)? I was activating skeletal mm pump so I didn’t get light headed & faint. Were usually in formation during these extended periods, fainting would have been very embarrassing for an officer and something my men and fellow officers would never let me forget.
What are the two ways that the respiratory pump returns blood to the heart? Inspiration: pressure lowers with the thorax & right atrium; increases pressure gradient & aids blood flow back to heart; Descent of diaphragm into abdomen raises intra-abd pressure & increases the pressure gradient to the thorax, favoring venous return
What are the components of control blood pressure? What component is controlled by the radius of blood vessels? Heart rate? Stroke volume? Blood Pressure = Cardiac Output x Total Peripheral Resistance; The radius of blood vessels is the main control of total peripheral resistance; Heart rate is a component of cardiac output; Stroke volume is a component of cardiac output.
Dr. P. has his blood pressure measured every Sunday and it usually is 125/75. What is my mean arterial pressure? Pulse pressure? 125 – 75 = 50/3 = 16.67 (17): 75 + 17 = 93 mm Hg:; 50 mm Hg
Where are the baroreceptors located? A drop in blood pressure has what reflexive affect on the cardiovascular center in the medulla? How does this increase blood pressure Carotid sinus & aortic arch; "CV center" in medulla: increase symp outflow & decrease parasymp (vagal); Increase symp innervation + decrease in vagal (parasymp) innervation= increase HR/contractility (CO) & increase vasoconstriction
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