Term
| Resistance to fluid flow in a vessel is directly and inversely related to what? |
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Definition
| The length of the vessel and the viscosity, and inversely to the 4th power of radius |
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Term
| What type of control unit can cut off blood flow to a capillary bed to modify blood flow? |
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Definition
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Term
| True or False: In a very metabolically active cell, like heart or lung, the capillary is a large distance away from the cells in order to create a large pool of nutrients. |
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Definition
| False, they often abut directly on cell with essentially no diffusion distance. |
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Term
| The constriction of arteries has little effect of flow, but constriction at ________ has a large effect on vacular resistance. |
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Definition
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Term
| Why does the left ventricle create a much higher level of pressure than the right ventricle? |
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Definition
| Since resistance is proportional to the length of the vessel the left ventricle must overcome the resistance of the entire arterial system versus the simple pulmonary system. |
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Term
| How do humans pump venous blood and lymphatic fluids? |
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Definition
| Through muscle contraction and one-way valves. |
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Term
| What is the difference in contraction of the right and left ventricles? |
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Definition
| The RV free wall contracts against the intraventricular septum, the LV twists the heart and shortens the ventricle. |
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Term
| Filling of the left ventricle is contributed by both _________ and _________? |
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Definition
| Elongation of the heart and untwisting of the ventricle |
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Term
| List these in order of most to least blood content: capillaries, arteries, veins. |
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Definition
| Veins, arteries, capillaries |
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Term
| Which node functions as a gating system to delay contractions in case of signal irregularities, the SA or AV node? |
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Definition
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Term
| What is the function of the left and right appendages of the heart? |
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Definition
| They have no active function except as an extra place to distend and collect blood for the atria. |
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Term
| What equation can you use to measure blood pressure? |
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Definition
BP=Cardiac Output * Resistance (BP = MAP-CVP) |
|
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Term
|
Definition
| The electrical signal of the SA node firing on the atria. |
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Term
| What segment of the EKG illustrates the brief delay in the electrical impulse passing to the ventricles? |
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Definition
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Term
| What is the QRS complex in the EKG? |
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Definition
| The electrical pulse contracting the ventricles. |
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Term
| What is the T wave in an EKG? |
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Definition
| The repolarization wave of epicardium to endocardium in the ventricles; whereas depolarization is from endo to epicardium |
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Term
| What segment of the EKG reveals the atrial repolarization? |
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Definition
| It is hidden from view because it occurs during the QRS ventricle depolarization |
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Term
| True or False: There is an occasional mechanical delay between excitation and contraction. |
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Definition
| False, there is always a delay |
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Term
| Describe what is heard during the two heart sounds S1 and S2. |
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Definition
| S1- AV valves closing, S2- aortic/pulmonic valves closing |
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Term
| What is the ejection fraction (percent of blood) of the RV and LV when they contract? |
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Definition
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|
Term
| What is the difference between the way the RV fills versus the LV? |
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Definition
| RV- passive flow from RA, LV- active aspiration from LA when mitral valve opens. |
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Term
| What is it called when a valve doesn’t close properly causing turbulence? |
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Definition
| Valvular insufficiency/incompetence with regurgitation of flow |
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Term
| What are the 3 phenomena that cause a murmur to occur? |
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Definition
| Stenosis/narrowing of valves causes turbulence; too much flow past a normal valve, like pregnancy or exercise; flow across a normal valve into a dilated artery. |
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Term
| How do you get calcium quickly to the myofilaments in the center of a cell? |
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Definition
| Through calcium channels (L-type) on the surface of the membrane and specifically in T-tubules that are present at every sarcomere in working ventricular myocytes |
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Term
| How do you get enough calcium into the cytoplasm with limited extracellular Ca in T-tubule space? |
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Definition
| Use a small amount of Ca going through L-type Ca channels (10-30%) to trigger large amounts of Ca release in the SR (70-90%). |
|
|
Term
| Where are L-type channels located versus RyR channels? |
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Definition
| L-type are in the myocyte membrane and T-tubule and the RyR are in the SR |
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|
Term
| How does the SR take up Ca to store it? |
|
Definition
| Through a ATP dependent Ca Pump. |
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Term
| Since the SR only takes up 2-4% of myocyte cell volume how does it hold all the calcium it needs? |
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Definition
| Through a molecule called Calsequesterin which bind 47 Ca ions per molecule. |
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Term
| What it Calsequesterin’s role as a calcium channel inhibitor? |
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Definition
| When Calsequesterin is not bound to calcium it binds to RyR/triadin/junction complex inhibiting Ca release; when it is calcium bound it diassociates from the complex |
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|
Term
| How is graded Ca release accomplished so as to match contractility requirements? |
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Definition
| L-type Ca channels in the T-tubule release Ca to adjacent SR RyR channels in a local fashion to form discrete plaque-like structures called Ca microdomains. |
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|
Term
| What is the term to describe the random opening of calcium channels in Ca microdomains that is visualized with confocal microscopy? |
|
Definition
|
|
Term
| Once released to activate contraction, how is Ca removed to facilitate relaxation in the cell membrane and SR? |
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Definition
| Through a surface membrane Na-Ca antiport exchanger and a ATP dependent Ca pump; the SR uses a SR Ca pump regulated by phospholamban. |
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Term
| True or False: the state of SR filling of Ca is determined by the competition between the SR Ca pump and the Na/Ca exchanger. |
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Definition
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|
Term
| When does the Na/Ca exchanger in the myocyte membrane remove Calcium the best? |
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Definition
| When the membrane potential is more negative or when cytoplasmic Na is lower. |
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Term
| What is the role of digitalis in depressing Na/Ca exchange thereby increasing contractility? |
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Definition
| It blocks the Na/K pump, increasing cytoplasmic Na, which slows Na/Ca exchanger, which allows SR Ca pump to take in more Ca, which allows the release of more Ca to contractile units. |
|
|
Term
| How are contractile force and relaxation rate interrelated? |
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Definition
| Through the SR Ca pump since 70-90% of Ca released is pumped back into the SR; increasing SR Ca pump rates enhances relaxation and stores more Ca to release for greater contractility. |
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Term
| Since sympathetic stimulation of the heart releases B-agonists which activate a PKA that phosphorylates targets in the cell, what 3 targets does it have that regulate contraction? |
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Definition
| Ca channels which increase their open probability, Phopholamban which removes its inhibitory effect on SR Ca ATPase, Troponin I which reduces Ca sensitivity of myofilaments to enhance relaxation. |
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|
Term
| What does parasympathetic activity do due regulate contraction? |
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Definition
| It releases Ach which activates inhibitory G-proteins, reducing cAMP, which limits PKA activity, which induces relaxation. |
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Term
| What goes wrong in heart failure due to chronic B-stimulation? |
|
Definition
| Hyperphosphorylation of RyR complexes, causing diassociation of accessory proteins, which increases the Ca sensitivity of RyR; this causes SR Ca leakiness in diastole (arrythmias) and depleting available calcium stores (depressing contractility. |
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|
Term
| How are B-blockers effective in heart failure? |
|
Definition
| They interrupt maladaptive remodeling including downregulation of SR Ca pump and upregulation of Na/Ca exchange which decreases contractility. |
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|
Term
| What is the equation for cardiac output? |
|
Definition
|
|
Term
| What three factors determine the amount of blood ejected per beat, ie stroke volume? |
|
Definition
| Preload, afterload, and contractility. |
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Term
| Differentiate preload, afterload, and contractility in regards to stroke volume. |
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Definition
| Preload - the volume in the ventricle at the beginning of contraction which relates to the length of the fiber or radius of ventricle; afterload - the equivalence of force needed to eject blood; contractility - the force with which the ventricle contracts independent of the preload or afterload. |
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Term
| True or False: Since BP measures flow and resistance you can equate that with the stroke volume afterload. |
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Definition
| False, although the BP is a reflection of the afterload it is not the afterload. |
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|
Term
| What is the law of La Place? |
|
Definition
| T~P*r, where T is wall tension, P is pressure inside the chamber, r is the chamber radius |
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|
Term
| What does compliance refer to in regards to the ventricle? |
|
Definition
| The passive distensibility of the ventricle during diastole to stretch during filling, it becomes progressively harder. |
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|
Term
| What ensures that the voltage signal triggering contraction spreads rapidly from cell to cell? |
|
Definition
| Electrical coupling of cells with gap junctions made of connexons |
|
|
Term
| What are connexons made of? |
|
Definition
| 6 connexin proteins=hemichannel=connexon, 2 connexons=a gap junction channel |
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|
Term
| What is the main function of cardiac AP upstroke? |
|
Definition
| To regulate conduction velocity between cells |
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|
Term
| Why do purkinje cells lack T-tubules? |
|
Definition
| Because their purpose is signal conduction not contraction |
|
|
Term
| Why does the SA & AV node and atrial myocytes lack T-tubules? |
|
Definition
| Because ventricular filling depends on suction created by ventricular relaxation (2/3 of filling occurs during first 1/3 of diastole, so atrial kick is surplus) |
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|
Term
| How do you ensure the current in the AP upstroke is large so that conduction velocity is fast? |
|
Definition
| Voltage-dependent Na current. |
|
|
Term
| How would you design current conduction in cardiac cells for regions in which slow conduction is desired? |
|
Definition
| No fast Na current like in myocardium and His-Purkinje cells, rely on slow Ca current like in SA and AV nodes |
|
|
Term
| What is the main function of the AP plateau duration in phase 2? |
|
Definition
| To regulate contractile force |
|
|
Term
| How is the duration of the AP plateau in phase 2 regulated? |
|
Definition
| Slow inactivation of Ca current and activation of time-dependent K currents will modulate the plateau |
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|
Term
| In phase 2 AP, how do B-agonists prevent AP duration from increasing since they tend to increase Ca current which normally increases AP duration? |
|
Definition
| They increase two outward currents of K and Cl which counteract the Ca inward current |
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|
Term
| During phase 3 AP, how do inward rectifier K channels (which mediate repolarization) assure rapid synchronous repolarization from the plateau back to the resting potential? |
|
Definition
| Positive feedback, K current gets larger as membrane potential becomes more negative |
|
|
Term
| In AP phase 4, how do we make a pacemaker to drive the heart, via diastolic depolarization? |
|
Definition
| Generate a progressive net inward current during diastole, and by using a voltage clock and a Ca clock to regulate depolarization through multiple currents |
|
|
Term
| How is the heart rate regulated by autonomic tone in phase 4 AP? |
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Definition
| By modifying maximum diastolic potential, diastolic depolarization, and AP threshold. |
|
|
Term
| Where does phase 4 spontaneous diastolic depolarization occur? |
|
Definition
| SA nodal, AV nodal and His-Purkinje cells |
|
|
Term
| What percentage of myocyte cell volume does mitochondria occupy? |
|
Definition
|
|
Term
| What is the function of titin muscle sarcomeres? |
|
Definition
| Titin is a long elastic protein that binds the thick filaments to actin and the Z-disk, it is spring like, absorbs most of the diastolic stress/force and is responsible for sarcomere uniformity. |
|
|
Term
| What happens to actin filaments during sarcomere contraction? |
|
Definition
| Crossbridges pull actin closer to the myosin A band and the actin filaments slide over each other. |
|
|
Term
| What happens to the rate of myosin cross bridge attachment as the level of intracellular Ca concentration goes up? |
|
Definition
| Higher Ca, more cross bridges attach to actin |
|
|
Term
| What is the rate-limiting step in the sarcomere cross bridge cycle? |
|
Definition
| The slow release of inorganic phosphate from the myosin head-ADP-Pi complex which makes this complex the majority of the form that you find these components in the cycle |
|
|
Term
| True or False: isometric contraction of myosin cross bridges shows that they exert a maximal force of 10 pN and it moves the unit 10 nm. |
|
Definition
| True, so this takes 20-30 cross bridge cycles during systole |
|
|
Term
| True or False: myosin cross bridge attachment to actin monomers creates a negative feedback loop that requires high amounts of calcium to expose more binding site. |
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Definition
| False, cross bridges work through cooperative activation by preventing tropomysoin from block activation sites, this allows other bridges to bind and creats a positive feedback loop. |
|
|
Term
| During resting conditions enough calcium is released during systole to produce _______ percent of maximal force that the heart is capable of. |
|
Definition
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|
Term
| What are the two major neurotransmitters, and what system do they work in, either para/sympathetic system? |
|
Definition
| Ach works in both, Norepinephrine works in sympathetics; side note - epi works in sympathetics as well |
|
|
Term
| True or False: Ach is the neurotransmitter of all preganglionic neurons and postganglionic parasympathetic neurons. |
|
Definition
| True, as well as postganglionic sympathetic nerves at sweat gland and adrenal medulla junctions. |
|
|
Term
| What are the two types of chonliergic receptors and where are they located? |
|
Definition
| Nicotinic - in all post-ganglionic cell bodies, cells of adrenal medulla, skeletal muscle cells; muscarinic - all structures innervated by PNS post-ganglionic nerves, sympathetic sweat glands |
|
|
Term
| What two molecules make up Ach and what are the two molecules the result in its breakdown? |
|
Definition
| AcetylCoA and Choline, then Choline and Acetate |
|
|
Term
| What are the four steps of Norepinephrine formulation? |
|
Definition
| Tyrosine->L-DOPA->Dopamine->Norepinephrine |
|
|
Term
| True or False: NE is the neurotransmitter for all post-ganglionic sympathetic neurons, except sweat glands |
|
Definition
|
|
Term
| True or False: Adrenergic stimulation leads to increased rate, contractility, and conduction velocity. |
|
Definition
|
|
Term
| True or False: the heart has an intrinsic rate of 50 bpm and is modulated by vagal tone to have a higher rate. |
|
Definition
| False, the rate is 100, but is modulated to keep it lower. |
|
|
Term
| What is the response of phase 4 spontaneous depolarization sinus rhythyms to PNS and SNS stimulation? |
|
Definition
| PNS reduces rate of depolarization and increases time to threshold, SNS does opposite |
|
|
Term
| Which, PNS or SNS, innervate the bronchial vasculature and the bronchial smooth muscle? |
|
Definition
| The SNS affects the vasculature, PNS innervates smooth muscle causing bronchoconstriction (but SNS releases EPI which causes bronchodilation) |
|
|
Term
| Of the two groups of leads on an ECG, which goes on the limbs and which goes on the chest - Columns I/II/III/aVR/aVL/aVF and Columns V1-6? |
|
Definition
| First groups on limbs, second of chest |
|
|
Term
| What happens during P wave, QRS wave, and T wave? |
|
Definition
| Atrial depolarization and contraction, ventricular contraction, ventricular repolarization |
|
|
Term
| How do you determine heart rate on an ECG? |
|
Definition
| Find a QRS complex that falls on a heavy line, start counting at the next heavy line like this 300, 150, 100, 75, 60, 50, 43 |
|
|
Term
| How do you determine heart rhythym of an ECG and what leads do you look at? |
|
Definition
| Look at lead II and V1, then identify P waves, QRS waves, and HR. |
|
|
Term
| How do you determine axis on an ECG? |
|
Definition
| Look at two leads, I and aVF, then since the heart is depolarized from the top to bottom and right to left this should lead to a positive deflection in both spots. |
|
|
Term
| In an ECG what are the 4 possible axis determinations in order of most to least common? |
|
Definition
| The first is normal with positive deflection in both lead I and AVF, the second is LAD with I being positive and AVF being negative, the third is RAD with I being negative and AVF positive, and the fourth is RAD extreme where both are positive. |
|
|
Term
| What is the PR interval in an ECG measure and what is normal? |
|
Definition
| The length of time for signal delay from SA node to AV node, normal being .12-.22 |
|
|
Term
| How do heart muscle cells increase force development without changing sarcomere length? |
|
Definition
| Sympathetic stimulation will phosphorylate L-type Ca channels, increasing their conductance, loading the SR with more Ca, and causing more Ca release. |
|
|
Term
| If blood pressure acutely rises by 40 mmHg, what would happen to left ventricular chamber size and what will happen to the wall stress as a consequence? |
|
Definition
| Size would increase, LV contractile stress would increase Increased afterload will decrease the stroke volume and thereby increase end systolic size. When the chamber refills for the next beat, its end diastolic volume will be greater than before, causing increased wall stress. |
|
|
Term
| Understand the following cross bridge cycle. |
|
Definition
|
|
Term
| Understand how the length of the sarcomere relates to the stress level in the following image. |
|
Definition
|
|
Term
| Understand the following which leads to use and what the deflections define as far as axis determination. |
|
Definition
|
|
Term
| The parasympathetic nervous system is also called the "cranialsacral outflow." Which cranial nerves give rise to parasympathetic, preganglionic neurons? |
|
Definition
CN III, VII, IX, X
(CN 3,7,9,10 for the Roman numeral-impaired)
Plus the sacrum |
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