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What is the function of the cardiovascular system?
Provides the transport system to continuously deliver nutrients and remove wastes from the tissues/cells.
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What are the three parts of the cardiovascular systems and what is the function of each?
- Heart - pump
- Blood vessels - delivery routes
- Blood - transport medium
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Two-thirds of the heart projects to the ______ of the midsternal line.
left
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What are the two layers of the serous pericardium and what is the function of each?
- Parietal - lines the internal surface of the fibrous pericardium
- Visceral - lines the external surface of the heart.
- Both secrete fluid to reduce friction.
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What are the three layers of the heart wall? Which is the thickest and serves as the functioning layer of the heart pump?
- Epicardium
- Myocardium - thickest
- Endocardium
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What chambers of the heart are the "receiving chambers" and which chambers serve as the actual "pumps" of the heart, propelling blood into circulation?
- Atria are receiving chambers
- Ventricles are the pumps
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Which chamber of the heart has, by far, the thickest wall and why?
The left ventricle - it pumps blood throughout the body.
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The heart is two side by side pumps each serving a different circuit. What are the two circuits and which side of the heart supplies blood to each?
- Pulmonary circuit - right side
- Systemic circuit - left side
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Which circuit contains a greater volume of blood?
Both circuits have an equal volume of blood.
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Which of the two ventricles has the greatest workload?
The left ventricle has a greater workload and is 3x as thick to manage it.
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What is the name of the arteries that supply oxygen and nutrients to the heart muscle (myocardium)? From where do these arteries arise?
Coronary arteries - arise from the base of aorta.
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What is angina pectoris? What causes it?
Thoracic pain caused by fleeting deficiency of oxygen in blood to coronary arteries.
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What is the technical term for "heart attack"? What is it caused by? What is the most common cause of death with a "heart attack"?
- Myocardium infarction
- Prolonged coronary blockage resulting in myocardial cell death in region of vascular deficiency.
- Arrhythmia
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What is the purpose of the heart valves?
Ensure unidirectional blood flow through heart.
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Which valves are the papillary muscles/chordae tendineae attached to? What is their function?
Atrioventricular valves - prevents prolapse of valves into atria.
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Both an incompetent (leaking/regurgitating) valve and a stenotic valve (valvular stenosis) cause the same problem for the heart. What is this problem and how does each of these two valvular abnormalities cause it?
- Heart's workload increases and may ultimately be markedly weakened.
- (Incompetent valve increases cardiac workload as it pumps the same blood over and over.)
- (Stenotic valve is stiffening that constricts the valve opening so the heart must contract more forcibly to overcome this narrowing.)
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Are cardiac muscles cells "striated"?
Yes.
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Do cardiac muscle cells contract via the sliding filament model?
Yes.
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Why does the cardiac muscle have so many more mitochondria than skeletal muscle?
For nearly exclusive aerobic respiration, constant supply of oxygen and ATP production.
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What is the adaptation, unique to cardiac muscle cells, that enables electrical coupling of all the cardiac muscle cells so that they can contract synchronously?
Gap junctions in the intercalated disc allow ions to pass from cell to cell so that adjacent cells are electrically coupled transmitting current across the entire heart.
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Why is it so important that cardiac muscle cells have such a long absolute refractory period?
To prevent tetanic contractions which would stop the heart's pumping action.
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What ion channel is unique to cardiac muscle cells that enables a long refractory period, as well as causing a much longer depolarization phase and contraction period of the muscle cell?
Slow calcium channel
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Will the heart continue to beat rhythmically if all of its nerve connections are severed?
Yes
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What system, unique to the heart, allows it to continue to beat rhythmically if all of its nerve connections are severed?
Intrinsic cardiac conduction system
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What ion channels create unstable resting potentials that enable autorhythmic cells to generate rhythmic impulses that pace the heart?
Slow sodium channels
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What serves at the heart's "pacemaker"? What is the "rhythm" it generates called? About how many "heart beats" per minute does it generate?
- Sinoatrial (SA) node
- Sinus rhythm
- Average 75 bpm
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If the heart's "pacemaker" is not functioning, the ____________ may take over as pacemaker (if ectopic focus does not), generating a heart rate of approximately ________.
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What are the last three components of the intrinsic cardiac conduction system? What is their depolarization rate? Is this enough to maintain adequate circulation in most people?
- -AV bundle (bundle of His)
- -Right and Left bundle branches
- -Purkinje fibers
- 30 bpm
- No
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The wringing motion of contraction of the heart's ventricles begins at _______ and moves toward the ________ ejecting blood into _______________.
- heart apex
- atria
- the large arteries leaving the ventricles
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What is arrhythmia? What is the arrhythmia that can cause sudden death?
- Irregular heart rhythm
- Ventricular fibrillation
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A(n) ____________ is a composite of all the action potentials being generated by nodal and contractile cells of the heart at a given time.
Electrocardiogram
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The P wave is indicative of depolarization of _________ the QRS complex shows ____________ and the T wave ____________.
- atria
- ventricular depolarization
- ventricular repolarization
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Elevated or depressed S-T segment on an EKG can be indicative of ________.
cardiac ischemia
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What are you hearing when you listen to the "heart sounds" with a stethoscope? What are abnormal heart sounds called? What are they usually indicative of?
- Closing of the heart valves
- Heart murmurs
- Valve problems
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What is the "cardiac cycle"?
All events associated with blood flow through the heart during one complete heart beat.
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What is systole?
Contraction
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What is diastole?
Relaxation
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During what part of the cardiac cycle does ventricular filling take place?
Mid to late ventricular diastole
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Does atrial contraction account for most of the filling?
No, 80% of blood passively flows into ventricles.
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What is end diastolic volume (EDV)?
Volume of blood in each ventricle at the end of ventricular diastole.
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What are the two phases of ventricular systole? Which valves are open and closed in each phase?
- Isovolumetric contraction phase - all valves closed
- Ejection phase - Semilunar (SL) valves open
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What is end systolic volume (ESV)?
Volume of blood remaining in each ventricle after contraction.
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What controls blood flow through the heart?
Pressure changes with flow down a pressure gradient through any available opening.
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What is cardiac output (CO)?
Volume of blood pumped by each ventricle in one minute.
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What are the two components of cardiac output (CO)? (Equation)
- CO = HR x SV
- Cardiac Output = heart rate x stroke volume
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How can we increase our cardiac output (CO) in response to demand?
Increase heart rate and/or stroke volume.
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What is the difference between resting and maximal cardiac output (CO) called?
Cardiac Reserve
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What is the "equation" for determining stroke volume (SV)?
SV = EDV - ESV
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What are the three main factors which affect stroke volume (SV)?
- Preload
- Contractility
- Afterload
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How does preload increase during exercise?
Increase venous return during exercise increases EDV and decreases ESV which increases SV.
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What is the definition of contractility?
Contractile strength at a given muscle length independent of muscle stretch and EDV.
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Why does increasing contractility result in an increase in stroke volume (SV)?
Decreases ESV
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What are two ways we can increase our heart's contractility?
- -Increased Ca2+ influx due to sympathetic stimulation
- -Hormones (thyroxine, glucagon, epinephrine)
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What is afterload?
Pressure that must be overcome for ventricles to eject blood.
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What is the main cause of increased afterload?
Hypertension
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Does hypertension increase or decrease stroke volume (SV)?
Decreases stroke volume, increases ESV
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What part of the nervous system exerts the most control over heart rate (HR)?
Autonomic nervous system
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Which part of the ANS increases HR and which part decreases HR?
- Sympathetic increases HR
- Parasympathetic decreases HR
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How is a trained athlete able to maintain normal circulation with a resting heart rate of 40 bpm?
Heart muscle strengthens which increases SV so they can maintain same resting CO with lower HR.
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What is tachycardia, bradycardia?
- Tachycardia is a fast heart rate (>100bpm)
- Bradycardia is a slow heart rate (<60 bpm)
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How can excessive degrees of tachycardia/bradycardia results in insufficient cardiac output (CO) to maintain adequate circulation to the tissues?
- Tachycardia - if persistent may lead to fibrillation
- Bradycardia - may result in grossly inadequate blood circulation
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How can hyperkalemia lead to cardiac arrest?
Lowers the resting potential
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What is congestive heart failure (CHF)?
Weakening of the myocardium by damage from various conditions can result in a chronic decrease output from the heart.
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Failure of which ventricle results in "excess fluid in lungs" (pulmonary edema)?
Left ventricle
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What are the two main causes of CHF?
- Coronary atherosclerosis
- Persistent high blood pressure
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What two types of congenital heart defects results in mixing of systemic and pulmonary blood? Why is this a problem?
- -Atrial and ventricular septal defects
- -Patent ductus arteriosus
- Inadequately oxygenated blood reaches body tissues.
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What is an artery? a vein?
- Arteries carry blood away from the heart.
- Veins carry blood to the heart.
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Do the pulmonary arteries carry oxygenated or deoxygenated blood?
Deoxygenated
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Which types of blood vessels are in contact with tissue cells and directly serve cellular needs?
Capillaries
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What are the three layers of the walls of the arteries and veins? What is each layer composed of and what is its primary function?
- Tunica intima - simple squamous epithelium - lines lumen of all vessels.
- Tunica media - smooth muscle and elastin - sympathetic vasomotor nerve fibers control vasoconstriction and vasodilation of vessels for control of blood flow and blood pressure.
- Tunica externa - collagen fibers - protect and reinforce.
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The aorta and its major branches are the ____________ arteries. What are two aspects of these vessels' structure that are critical to their function?
- elastic (conducting)
- -elastin in all 3 tunics
- -large lumen
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What type of arteries control flow into the capillary beds via vasodilation and vasoconstriction?
Arterioles
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How many cells thick is the wall of a capillary?
One
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How does the thickness of a capillary wall relate to its function?
By being one cell thick it allows the exchange of materials (gases, nutrients, wastes, hormones) between the blood and the interstitial fluid.
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The most common type of capillary are continuous capillaries. If they are "continuous" how do fluids pass from the blood to the interstitial spaces?
Tight junctions connect endothelial cells, they are incomplete and intercellular clefts allow the passage of fluids and small solutes.
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What type of capillaries are found in the kidneys?
Fenestrated capillaries
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How is the structure of fenestrated capillaries in the kidneys adapted to the function of this organ?
The kidneys function as filters so fenestrated capillaries contain pores and are much more permeable to fluids and solutes than continuous capillaries.
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What are the two types of vessels in capillary beds?
- Vascular shunt
- True capillaries
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How is blood flow through the capillary beds controlled?
Cuff of smooth muscle fibers called precapillary sphincters surrounds the root of each true capillary at the metarteriole and acts as a valve to regulate blood flow into the capillaries.
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Veins have _____ walls and _____ lumens than arteries.
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Why are veins called capacitance vessels or blood reservoirs?
Veins can contain up to 65% of the blood supply.
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What structural adaptation of veins, particularly in the limbs, help maintain the flow of blood back toward the heart?
Large diameter lumens offer little resistance and valves formed from folds in the tunica intima prevent backflow of blood.
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What homeostatic imbalance results if the valves in veins become incompetent? Where is this abnormality most common? What are two risk factors for this condition?
- Varicose veins - tortuous, dilated veins due to incompetent valves.
- Most common in superficial veins of legs.
- -Heredity
- -Conditions that hinder venous return (prolonged standing, obesity, pregnancy)
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What is the purpose of arterial anastomoses at the base of the brain (circle of Willis)?
Provide alternate pathways (collateral channels) to a given body region.
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The homeostatic imbalance of arteries responsible for 50% of US deaths is ________. Death from this abnormality is most likely when it occurs in the _____ and _____ arteries where it can cause ______ and _______.
- atherosclerosis
- coronary
- carotid
- myocardium infarction
- stroke
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What is thought to be the first step in the formation of atherosclerotic plaques?
damage to the tunica intima
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Which type of cholesterol containing lipoprotein is responsible for the accumulation of fats in atherosclerotic plaques and which is protective against this accumulation?
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What happens to atherosclerotic plaques that usually results in death (sometimes sudden) due to MI or stroke?
Plaque becomes unstable: can ulcerate and rupture, causing platelet adhesion and thrombus formation.
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Which four risk factors for atherosclerosis are theoretically under our control?
Smoking, obesity, diet, exercise
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What are two types of medications that can help reduce risk of atherosclerosis if lifestyle changes are not successful?
- Anti-hypertensive medications
- Cholesterol lowering drugs (statins)
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What is the point of taking one baby aspirin a day?
Reduces platelet aggregation.
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What is the definition of blood pressure?
Force per unit area exerted on the wall of a blood vessel by the blood (mmHg)
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What is the driving force that keeps blood moving from the heart toward the tissues?
Pressure gradient
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What is "resistance"?
Opposition to flow
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Where in the vascular system is the most resistance encountered?
Periphery of systemic circulation
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Variation of what vascular parameter is utilized by the body to alter peripheral resistance? What type of vessel is most important in this process?
- Changes in blood vessel diameter
- Small diameter arterioles
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What is the formula that expresses the relationship between blood flow, blood pressure and resistance?
- F = deltaP/ PR
- Blood Flow = Blood Pressure Gradient / Peripheral Resistance
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What is "normal" blood pressure?
110 to 140 over 70 to 80
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What is pulse pressure?
Difference between systolic and diastolic pressure
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What is mean arterial pressure (MAP)?
Pressure that propels the blood to the tissues
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Why do pulse pressure and mean arterial pressure (MAP) both decrease as one moves further away from the heart?
- MAP decreases due to friction
- Pulse pressure decreases as arteries become more muscular (less elastic)
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Why is low capillary blood pressure desirable?
High BP would rupture fragile, thin-walled capillaries. Most are very permeable, so even low pressure forces solute containing fluid out of blood stream and into interstitial spaces.
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What are three functional adaptations utilized to help return blood to the heart from the low pressure venous system?
- Respiratory pump
- Muscular pump (most important)
- Sympathetic control
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How does exercise increase the efficiency of the mechanisms to return blood to the heart? Why is this increased efficiency important?
- Increases CO via increased venous return (increased EDV)
- Because muscles need lots of blood for exercise.
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Why is maintaining adequate blood pressure crucial for body homeostasis?
To maintain a steady flow of blood from the heart to the periphery is vital for organ function.
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What are the three factors which can be varied to influence systemic blood pressure? Which of these factors is utilized for short-term control of blood pressure? Which for long-term?
- CO = deltaP / PR
- Cardiac Output - short-term
- Peripheral Resistance (PR) - short-term
- Blood Volume - long-term
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In a low blood volume/low blood pressure situation how can neural controls maintain blood flow to vital organs (brain, heart, kidneys)?
Constrict all blood vessels except those supplying heart and brain so blood perfuses those vital organs.
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The cardiovascular center in the medulla is composed of _______ center which maintains short-term blood pressure control by altering _______ and the __________ center which controls blood pressure by altering ________________. The ________ branch of the _________ nervous system mediates these changes.
- cardiac
- cardiac output
- vasomotor
- peripheral resistance
- sympathetic
- autonomic
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How does the vasomotor center monitor blood pressure (what two types of receptors does it receive input from)? What variables does each type of receptor monitor?
- Baroreceptors - pressure sensitive
- Chemoreceptors - changes in blood levels of carbon dioxide, oxygen, hydrogen ions.
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Where are the baroreceptors located that help protect the blood supply of the brain?
Carotid sinus reflex
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What changes in the blood would chemoreceptors detect that would signal the cardiovascular center that an increase in blood pressure was called for? Why?
- Increase in carbon dioxide and decrease in pH or oxygen
- Because you need more oxygen/nutrients where metabolic processes are occuring.
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What organ is predominately involved in long-term regulation of blood pressure? What variable does it utilize to control BP?
-
In regard to long-term regulation of blood pressure, how does the direct mechanism work?
Alters blood volume independently of hormones.
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What hormone is utilized for indirect mechanism (for long-term regulation of blood pressure)?
Angiotensin II
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How does angiotensin II increase blood pressure?
It's a potent vasoconstrictor, stimulates aldosterone secretion, stimulates ADH release which increases blood volume.
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What is orthostatic hypotension? In what age group is it most common?
- Temporary low BP and dizziness when suddenly rising from a sitting or reclining position.
- Elderly.
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Why is chronic hypertension so dangerous (what does it damage and what diseases does this lead to)?
- It damages blood vessels and strains the heart.
- Leads to CHF.
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Which is more common, primary hypertension or secondary hypertension?
Primary hypertension (90% of cases)
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What causes primary hypertension?
Complicated interplay of several risk factors: heredity, diet, obesity, age, stress, diabetes mellitus, smoking, and nicotine
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What are the four critical processes which occur with tissue perfusion?
- Delivery of oxygen/nutrients to, and removal of wastes from, tissue cells.
- Gas exchange
- Absorption of nutrients
- Urine formation
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Why is the velocity of blood flow the slowest in the capillaries of any other blood vessels?
Allows adequate time for exchange between blood and tissues.
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What is autoregulation of blood flow?
Automatic adjustment of blood flow to each tissue in proportion to its requirements at any given point in time.
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What are the two types of controls involved in autoregulation of blood flow?
-
Accumulation of what metabolic substances results in vasodilation in any given organ or tissue? Why is this vasodilation beneficial to homeostasis?
- H+, K+, adenosine and prostaglandins and inflammatory chemicals.
- Because you need more oxygen/nutrients where metabolic processes are occuring.
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What do vascular endothelial cells release to cause vasodilation as a result of accumulation of metabolic substances?
Nitrous oxide (NO)
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What are two ways that blood flow to skeletal muscle increases during exercise.
- Blood flow increases in direct proportion to the metabolic activity.
- Sympathetic nervous system constricts arterioles of digestive viscera and skin to divert it to muscles.
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What are the two functions of the cutaneous (skin) circulation that are extremely important to overall homeostasis and are relatively unique to this circulation?
- Maintains body temperature.
- Provides blood reservoir.
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What is typical blood pressure in the pulmonary arteries? How does this compare to the systemic circulation?
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How are metabolic autoregulatory controls of pulmonary blood flow different than all other tissues? Why are they different?
- They are opposite.
- Low oxygen levels cause vasoconstriction, high oxygen levels promote vasodilation.
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Why is increased blood flow in coronary arteries critical to meet the needs of a more vigorously working heart?
Increased blood flow is critical to meet increased demand as at rest cardiac cells use as much as 65% of the delivered oxygen so increasing blood flow is the only way to make sufficient oxygen available to a more vigorously working heart.
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By what mechanism do most respiratory gases and nutrients pass between blood and interstitial fluid? Why does this result in oxygen flowing out of the blood and into the tissues?
- Diffusion
- Concentration gradient
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_________ pressure and ________ pressure are the two types of pressure that determine the direction of the bulk fluid flows into and out of the capillaries. At the arterial end, _______ pressure dominates, forcing fluid __________ and at the venous end, _________ pressure dominates drawing fluid _________.
- Hydrostatic
- colloid osmotic
- hydrostatic
- out of blood
- osmotic
- back into blood
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What is circulatory shock?
Any condition in which blood vessels are inadequately filled and blood cannot circulate normally.
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What are the three types of circulatory shock? Which type is caused by extreme vasodilation?
- Hypovolemic shock
- Vascular shock - extreme vasodilation
- Cardiogenic shock
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What are two common examples of vascular shock and what causes vasodilation in each?
- Anaphylactic shock - systemic allergic reaction in which body wide vasodilation is triggered by massive histamine release.
- Septic shock - caused by septicemia in which bacterial toxins cause vasodilation.
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What are the four structures unique to the fetal circulation and why do they exist?
- Foramen ovale and ductus artenous - bypass nonfunctioning lungs
- Ductus venous - bypass liver
- Umbilical vein and arteries - circulate blood to/from the placenta where gas and nutrient exchange occurs with the mother's blood
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Why do premenopausal women have such low incidence of atherosclerosis? At what age do the risks of cardiovascular disease become equal in men and women?
- Protective effects of estrogen
- Age 65
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What are the three parts of the lymphatic system?
- Lymphatic vessels
- Lymph
- Lymph nodes
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What are the two critical functions of the lymphatic system?
- Control of blood volume
- Immune system
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How does the extreme permeability of lymph capillaries enhance the defense function of the lymphatic system?
Allows for uptake of large particles such as cell debris, pathogens and cancer cells.
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What are the two lymphatic ducts? Which one drains the majority of the body?
- Right lymphatic duct
- Thoracic duct - majority of body
-
What is the name of the sac anterior to the upper lumber spine where the thoracic duct originates?
Cisterna chyli
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Where do the lymphatic ducts empty their lymph?
Into venous circulation at the junction of the internal jugular and subclavian veins.
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What are the two types of lymphocytes? What important role does each play in the immune system?
- T-cells - manage the immune response, attack and destroy foreign cells
- B-cells - produce plasma cells which secrete antibodies (mark antigens for destruction by phagocytes)
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What role do macrophages play?
Phagocytize foreign substances and help activate T-cells.
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What type of tissue are lymphoid tissues/organs largely composed of?
Reticular connective tissue
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What two important functions to lymphoid tissues/organs perform as part of the immune system?
- Houses and provides a proliferation site for lymphocytes.
- Furnishes a surveillance vantage point for lymphocytes and macrophages.
-
What are the principal lymphoid organs or the body?
Lymph nodes
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In what tissue are lymph nodes located? Where are they near the body surface?
- Embedded in connective tissue in clusters along lymphatic vessels.
- Near body surface in inguinal, axillary, cervical regions.
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What are the two primary functions of lymph nodes?
- Filter lymph - macrophages destroy microorganisms and debris.
- Immune system - lymphocytes are activated and mount an attack against antigens.
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What is lymphadenopathy?
Swollen/enlarged lymph nodes.
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What are two types of causes of lymphadenopathy? How can the cause be hypothesized by physical examination of these lymph nodes?
- Infectious - tender
- Neoplastic (cancer) - hard and non-tender
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What is the largest lymphoid organ in the body? What are its two main functions?
- Spleen
- -Site of lymphatic proliferation and immune surveillance and response.
- -Cleanses the blood of aged and defective blood cells, platelets and debris.
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What is the function of the tonsils? How do they perform this function?
Crypts trap bacteria and particulate matter entering pharynx in food and inhaled air.
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What comprises the mucosa-associated lymphatic tissues (MALT) and what is their function?
- Peyer's patches, appendix, tonsils, lymphoid nodules in walls of bronchi.
- Protects passages open to exterior from foreign matter.
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