Exam 3 - Circulatory System Flashcards
The formed elements of blood.
Erythrocytes/RBCs, leukocytes/WBCs, and plateletes/thrombocytes.
Liquid formed elements of blood are suspended in.
Plasma
The percentage of blood volume that is RBCs.
Hematocrit
Normal blood volume of an adult.
5 Liters
Average hematocrit of an adult.
39-43%
Motion of blood through the vessels.
Bulk flow
Branches of arteries.
Arterioles
Branches of veins
Venules
Structure that allows substances to enter and leave blood by crossing its walls.
Capillaries
Structures that form capillaries.
Smallest arterioles
Pulmonary circulation of blood.
Right ventricle => Pulmonary trunk (i.e. divides into r/l pulmonary arteries => pulmonary capilaries => pulmonary veins (4) => left atrium
Systemic ciculation of blood.
Left ventricle => Aorta => Systemic capillaries => Superior and inferior venae cavae => Right atrium
Circuit that allows blood to go from the systemic veins to the systemic arteries.
Pulmonary circuit
Does more blood pass through the systemic than the pulmonary circuit in a given volume of time?
No
Sac that surrounds the heart
Pericardium
Extra outer layer around the heart.
Fibrous pericardium
Cardiac muscle tissue forming the bulk of the heart walls.
Myocardium
Divides the heart longitudinally into two functionally halves (i.e. each half contains an upper atrium and lower ventricle)
Interventricular septum
True/False: Blood normally flows between two atria or two ventricles.
False
Recieves blood pumped via the right heart.
Lungs
Recieves blood pumped via the left heart.
Other organs than the lungs (i.e. the systemic circuit)
A weak primer pump for each ventricle.
Atrium
Structures that allow blood to flow from atrium to ventricle but not vice versa.
Atrioventricular valves
Valve between the right atrium and right ventricle.
Tricuspid valve
Valve between the left atrium and left ventricle.
Bicuspid valve
True/False: Opening and closing of a valve (i.e. AV or semilunar) is an active process caused by the pressure differences across the valve.
False: It is a passive process
Structures that allow blood to flow from ventricle to outflow tube (i.e. pulmonary trunk or aorta) but not vice versa.
Semilunar valves
Valve between the right ventricle and pulmonary trunk.
Pulmonary (semilunar) valve
Valve between the left ventricle and the aorta.
Aortic (semilunar) valve
Inappropriate pushing of an AV valve into an atrium.
Prolapse
Fibrous cords that prevent prolapse.
Chordae tendineae
Muscles of the heart that limit the movement of the AV valves (i.e. do not open/close valves).
Papillary muscles
True/False: Chordae tendinae are not attached to semilunar valves.
True
Arterial branches coming off of the aorta that are the heart muscle’s blood supply.
Coronary arteries
Electrical event that causes contraction in the heart (i.e. a mechanical event).
Depolarization
Electrical event that causes relaxation in the heart (i.e. mechanical event).
Repolarization
Fill in: All the cardiac muscle fibers of a given chamber must contract almost ___ to produce a single, coordinated squeezing action therefore they must ___ almost simultaneously.
Simultaneously; depolarize
Specialized communicating junctions (i.e. formed from protein channels/tubes) between adjacent cardiac muscle cells that permits rapid spread of an action potential from cell to cell (i.e. does not require the release of transmitter)
Gap junctions
Formed by the cells of both ventricles (i.e. and separately all fibers of both atria). Allows the excitation of one cell to result in the action potential to spread to all cells of the fiber.
Syncytium
A unique network of non-contracting/weakly contracting cells which are electrically connected with other “ordinary” cardiac muscle cells, that facilitates the rapid and coordinated spread of excitation.
Conducting system
True/False: Some cardiac muscles cells are capable of rhthymic self-excitation
True
Fill in: A cardiac muscle cell capable of rhythmic self-excitation undergoes gradual depolarization, until it reaches threshold, at which point an ___ ___ occurs.
Action potential
Gradual depolarization of the heart’s membrane potential due to leakiness to sodium and other ions.
Pacemaker potential
Fastest autorhythmic cells massed in the wall of the right atrium, connected to “ordinary” atrial muscle cells by gap junctions
Sinoatrial node/SA node/Sinus node
Most conducting system cells are driven by the action potentials of this structure due to it having the fastest autorhythmic rate.
SA node
A pacemaker not located in the SA node.
Ectopic pacemaker
General flow of electrical excitation throughout the conduction system of the heart.
Sinoatrial node => Atrioventricular node => Atrioventricular bundle => R/L Bundle branches => Purkinje fibers
ECG result from depolarzation of fibers of both atria.
P wave
ECG results from depolarization of fibers of both ventricles.
QRS complex of waves.
ECG results from repolatization of fibers of both ventricles.
T wave
Why is atrial repolarization not seen on ECG?
Occurs at the same time as QRS complex
True/False: ECG recordings are intracellular.
False, extracellular
Interval that approximates the time which the atria contract and thus generate force/tension.
PR interval
Interval that approximates the time during which the ventricles are contracting and thus generating force/tension.
QT interval
Placement of reference and recording electrodes of lead I
Right and left arms
Placement of reference and recording electrodes of lead II.
Right arm and left leg
Placement of reference and recording electrodes of lead III.
Left arm and left left
Placement of ground electrode.
Right leg
How does the action potential in ventricular muscle cells differ than neuron/skeletal muscle action potentials?
Has a long conintues depolarization (i.e. plateau)
What causes the initial rising phase of the action potential in cardiac muscle cells?
Increase in permeability to sodium ions (i.e. same as neuron or skeletal muscle cell)
Structures that contains slow voltage-gated calcium ion channels that open during initial depolarization in cardiac muscle cells (i.e. responsible for plateau).
T-tubules
What stimulates the release of a large amount of calcium stored inside cardiac muscles cells (i.e. stored in sarcoplasmic reticulum)?
Calcium entering from outside the cell during plateau
Generally describe the flow of excitation-contraction coupling.
Excitation (i.e. depolarization of plasma membrane) => slow calcium channels found in t-tubles opens => calcium flows into cytosol => cytosol stored in sarcoplasmic reticulum are released => calcium flows into cytosol => cytosolic calcium concentration increases => contraction occurs
Period after a muscle cell makes an action potential which it cannot be re-excited.
Refractory period
The refractory period of a cardiac muscles is [>, <, =] to skeletal muscle.
>
Addresses a stronger than normal contraction of the heart due to premature firing of a ventricle resulting in more blood flowing into the ventricle.
Frank-Starling law
Period of ventricular contraction (i.e. consists of a brief period of isovolumetric ventricular contraction and a large period of ventricular ejection)
Systole
Period of ventricular relaxation (i.e. consists of a brief period of isovolumetric ventricular relaxation and a large period of ventricular filling)
Diastole
Vibrations and turbulent blood flow doe to valves closing.
Heart sounds
Sound due to closure of AV valves
Sound 1/Lub
Sound due to closure of aortic and pulmonary semilunar valves.
Sound 2/Dub
Period of ventricular filling
Second stage of diastole
Amount of blood in the ventricle at the very end of diastole.
End-diastolic volume (EDV)
Amount of blood remaining in the ventricle after ventricular ejection.
End-systolic volume
When during the cardiac cycle is aortic (i.e. atrial presure) rising? Why?
The first half of the second stage of systole; Rate blood being added to aorta via ventricle > Rate blood leaving aortic branches into capillaries
When duirng the cardiac cycle is aortic (arterial) pressure falling? Why?
Mid-to-late-systole; Amount of blood leaving the aorta > amount of blood being added to it
When during the cardiac cycle is ventricular pressure rising? Why?
Isovolumetric ventricular contraction and first-half of ventricular contraction (i.e. systole); Mostly due to ventricular muscles contracting
When during the cardiac cycle is ventriclar pressure falling?
Mid-to-late systole and isovolumetric ventricular relaxation
When during the cardiac cycle is ventricular volume rising?
Most of diastole
When during the cardiac cycle is ventricular volume falling?
Most of systole
When during the cardiac cycle is ventricular volume constant?
Isovolumetric contraction or Isovolumetric relaxation
When during the cardiac cycle does the P wave occur? Why is this significant?
End of diastole; Depolarization of atrium continues to add blood to the ventricle
When during the cardiac cycle does the QRS complex occur? What is its significance?
Isovolumetric ventricular contraction (i.e. first stage of systole); Contracts ventricle pushing blood from ventricle to the aorta/arteries
When during the cardiac cycle does a T wave occur? What is its significance?
Mid-to-late systole; Relaxes the ventricle
When during the cardiac cycle does heart sound 1 occur?
End of diastole
When during the cardiac cycle does heart sound 2 occur?
End of systole
When during the cardiac cycle does the bicuspid valve open?
The end of isovolumetric relaxation
When during the cardiac cycle does the bicuspid valve close?
The end of diastole/beginning of isovolumetric contraction
When during the cardiac cycle does the semilunar valve open?
End of isovolumetric contraction
When during the cardiac cycle does the semilunar valve close?
End of systole/beginning of isovolumetric relaxation
Small, brief surge of aortic pressure due to the closure of the aortic semilunar valve.
Incisura
When during the cardiac cycle does incisura occur?
Isovolumetric relaxation
Volume of blood pumped by each ventricle per unit time.
Cardiac output
Equation for cardiac output
CO = HR X SV
Average cardiac output
5 L/min
Volume of blood ejected by each ventricle during each contraction.
Stroke volume (SV)
Equation for stroke volume.
SV = EDV - ESV
Stimulation of the SA node that increases HR via norepinephrine.
Sympathetic stimulation
Stimulation of SA node that decreases HR via acetylcholine.
Parasympathetic stimulation
Structure that releases norepinephrine that increases HR. Acts on the same receptors norepinephine from the sympathetic stimulation utilizes.
Adrenal medullae
General mechanism of HR control.
Substances change the permeability of SA node cells to various ions thus changing the slope of their gradual depolarization towards threshold
What controls stroke volume (SV)?
Strength of contraction
How would an increase in blood from the veins to the heart effect heart output?
Increase
Fluid accumulation in interstitial spaces of the lungs which could be due to ineffective pumping of the left ventricle.
Pulmonary edema
Where would congestion occur if the right ventricle failed to properly pump blood?
Veins and eventually extremities
The strength of contraction at any given end-diastolic volume.
Contractility
What increases contractility
Sympathetic input to the ventricles as well as plasma epinephrine
What results from an increase in contractility?
More complete ejection of EDV
Ratio of stroke volume to end-diastolic volume.
Ejection fraction
Average ejection fraction at rest.
50-75%
Structures that transport blood to tissues under high pressure.
Aorta and large arteries
Structure that serves as the main control site for blood flow (i.e. also major site of resistance to flow in circulation)
Arterioles
Structure that serves as the major site of water and solute exchange between blood and tissues.
Capillaries
Structure that returns blood to the heart under low pressure and serves as a reservior of blood.
Venules and veins
In what structures of the cardiovascular system is pressure pulsatile?
Arteries and arterioles
True/False: The high pressure in veins is dissipated as blood flows through while pressure in large arteries is only slightly greater than 0.
False
