CV Phy And Path 1 Flashcards
What is the effect of giant cell arteritis?
Inflammed vessel
Size of lumen is reduced
Can cause bitemporal vision loss
Describe the contents and purpose of plasma.
55% of blood fluid in humans
92% water
8% glucose, hormone, proteins, mineral salts, fats, vitamins
Describe RBC (erythrocytes). How does the shape aid in function?
Transport oxygen to and from lungs
Hemoglobin binds to oxygen
Shape increases surface area and allows them to fold to squeeze through small spaces
Describe WBC (leukocytes)
Vital defenses against disease and infection
What is the total volume of the blood?
4-5L
Describe platelets.
Interact with clotting proteins to prevent or stop bleeding
Describe the 3 methods by which CO2 is transported in the blood through capillaries.
CO2 carried in RBC
HCO3- (CO2 and H2O) dissolved in plasma as carbonic acid CO2 from tissues dissolved in plasma
Describe the function of the lymphatic system in the cardiovascular system.
Lymphatic system collects excess fluid that drains from cells and tissue throughout the body and returns it to the bloodstream
Recirculated though the body
Describe the overall arrangement of the cardiovascular system.
Heart is 2 pumps for 2 systems arranged in series
Systemic circulation and pulmonary circulation are arranged in series
Flow in all portions ranged in series must be the same
Subdivisions in each system arranged in parallel
Flow of portion in parallel must sum to equal flow in the system
What must be true regarding the flow in portions that are parallel in the cardiovascular system?
Incoming must equal outgoing (equal flow)
Define pressure.
Generated from myocardial contractions and stenosis of ventricles
Contract increases pressure
What is vascular resistance determined by?
Vessel diameter
Blood viscosity (high cholesterol, polycythemia increased RBC, anemia)
What effect does high cholesterol have on resistance? Polycythemia? Anemia?
Increases resistance , Decreases blood flow (clotting)
Increase resistance
Decrease resistance, decrease viscosity, decrease blood flow
What is the equation for determining blood flow rate? What are the determinants for blood flow?
P1-P2 (pressure gradient)/ Resistance
Pressure and resistance
Are pressure gradients necessary?
Yes needed for blood to flow
What are the layers of lumen in the heart?
Innermost- tunica intima
Tunic media (muscular)
Outermost- tunica adventitia
Describe the layers of histology in the heart. What are the coronary arteries?
Endocardium
Homologous with tunica intima
Dense fibroelastic CT, Continuous with valves
Myocardium
Homologous with tunica media
Epicardium
Homologous with adventitia
Pericardium
Coronary arteries
Homologous with vasa vasorum
(a network of small blood vessels that supply the walls of large blood vessels)
What are pace maker cells?
Non-contractile cardiac muscle
Rhythmic electric signals create action potential so heart can function on its own
Describe a cardiac myocyte.
Composed of bundles of myofibrils that contain myofilaments
Myofibrils have repeating microanatomical units
Mono or bi nucleated, frequent cell bifurcations
Describe sacromeres.
Basic contractile units of myocyte
Composed of thick and thin filaments, myosin and actin
Describe the cell junctions that exist between cardiac myocyte cells.
Intercalated discs: cell junctions
Mechanical coupling- desmosomes
Electrical coupling- gap junctions
Frequent cell bifurcations
These connections allow for the rapid travel of signals within the heart
What are transverse tubules (T-tubule) in the cardiac myocyte?
Invaginations of the cell membrane
Permit rapid transmission of the action potential into the cell
Regulate cellular calcium concentration
Describe the function of the sarcoplasmic reticulum (SR) and the SR Dyads.
SR: Stores calcium
SR dyads: functional junction formed by t-tubules and SR, within each dyad calcium entry through T-tubules elicits calcium release from SR
What organelles play an important role in the cardiac muscle?
Mitochondria
What is the basic sequence of the cardiac cycle? What does it result in?
Atrial systole and diastole
Ventricular systole and diastole
Results in pulsation blood flow in the arteries
What is a sphygmomanometry?
Measures arterial pressure changes (bp pump, gage, cuff)
measure bp
Systolic pressure/diastolic pressure
What is pulse pressure equal to for a Sphygmomanometry? Is it a reliable measurement?
Pulse pressure= systolic pressure - diastolic pressure
Not reliable, someone in hyp crisis could have the same different as someone with normal BP
How is mean arterial pressure calculated for Sphygmomanometry? Is it reliable?
Mean arterial pressure = 1/3(pulse pressure) + diastolic pressure
Reliable, shows average BP overtime
Where is pulsatile flow the greatest?
In the aorta
What occurs during systole?
Inflow is greater than outflow
Increase in arterial volume
Increase in arterial pressure
What occurs during diastole?
Outflow is greater than inflow
Arterial volume decreases
Arterial pressure decreases
Describe the autorhymicity of the heart?
Controlled by pace marker cells (under autonomic control)
Cardiac muscle acts as 2 separate single unit muscles: atrial and ventricular
Electrical and mechanical coupling in intercalated discs
What is the basal electrical rhythm (BER)?
Present in all cardiac muscle fibers
Cyclical BER activity of the pacemaker cells in SA node regulates rate of myocardial muscle contractions
Describe the order of the cardiac conduction system.
Sinoatrial node
Atrioventricular node
Atrioventricular bundle (Bundle of HIS)
Bundle branches
Purkinje fibers
What is the function of the internodal pathway?
Connects SA node to AV node
Signals between pacemaker cells
What is the function of bauchmann’s bundle?
Conducts impulses from R to L atrium
Simultaneous contraction
What is the function of the SA node? Where is it located?
Pacemaker (ANS can act on this)
Generate impulses
Border of superior VC and RA
What is the function of the AV node? Where is it located? Describe AV delay.
After SA node at the base of RA
Delays signals we don’t want A and V to contract at same time (A must contract first)
Also contains pacemaker cells
Describe the bundle of His.
Connects the atria to the ventricles
Describe the bundle branches.
Conduct the impulses through the interventricular septum
Describe the purkinje fibers.
Depolarize the contractile cells of both ventricles to cause ventricular contraction
What is the difference between effect of depolarization vs hyperpolarization?
Depolarize = contract
Hyperpolarize = relax
Describe the function of diastolic depolarization.
Occurs spontaneously
Slow influx of Na from leaky channels to return pacemaker cell to threshold
Determines heart rate
Deceive the order of pacemaker potentials.
Begins at -40mV (threshold)
Phase 4: slow influx of Na+ (prepotential) to reach threshold)
Phase 0: Rapid influx of Ca2+ (depolarization, cell becomes positive)
Phase 3: outflux of K+ (repolarization, cell becomes more negative/less positive)
Leaky channels allow for diastolic depolarization back to threshold
Which phase describes the change in depolarization that is associated with sympathetic and parasympathetic stimulation?
Phase 4
Describe the effects of sympathetic stimulation on the action potential of pacemaker cells.
Sympathetic stimulation and epinephrine depolarize the pacemaker cell and speed up the depolarization rate (spontaneous diastolic depolarization)
Increases heart rate
Describe the effects of parasympathetic stimulation on the action potential of pacemaker cells.
Parasympathetic stimulation hyperpolarize the pacemaker cell and slows depolarization
Decreases heart rate
Starts at a more negative membrane potential
What is the average BPM of the heart produced by BER?
100 Bpm
What controls firing of the SA?
ANS
What is the effects to heart rate with cardiac accelerator nerve (sympathetic) and vagus nerve (parasympathetic)?
Sym: tachycardia > 100BPM
Para: Bradycardia: <60BPM
What is the difference between stimuli for cardiac muscle vs pacemaker cells?
Muscles receive external stimuli while pacemakers receive internal signals
What is the order of phases for muscle cells vs pacemaker cells?
Muscle: 4, 0, 1, 2, 3, 4, repeat
Pacemakers: 4, 0, 3, 4 repeat
Describe the process of the ventricular cardiac muscle action potentials.
Phase 0 - fast depolarization (+)
Influx gNa+, outflux gK+
Phase 1 - slight repolarization
– decreased influx gNa+
Phase 2 - plateau
– Balanced increased influx gCa2+ (contraction) and increased outflux gK+
Phase 3 - repolarization
– decreased influx gCa2+ and increased outflux gK+
Phase 4 - Resting
– Approx. 300 mSec
Describe the refractory period of the muscle cell action potential.
Absolute: no summation of excitatory cell (myocyte will not contract)
Relative: supranormal excitability (premature ventricular contraction before it is totally filled)
What is the longest phase of muscle cell action potentials?
Phase 2
