What are the steps of hemostasis?
1. vascular spasm, blood vessel vasoconstricts
2. platelet plug formation, collagen fibers exposed, platelets aggregate
3. coagulation, reinforces platelet plug with fibrin threads
What are the phases of coagulation?
1. prothrombin activator
3. fibrin threads
What is ADP? (related to platelet plug formation)
a potent aggregating agent that causes more platelets to stick together, so more chemicals are released, aggregating more platelets (positive feedback)
What is thromboxane?
messenger that enhances vascular spasm and platelet aggregation
Name a few anticoagulants.
Plavix, Aspirin, Coumadin, Heparin, Lovenox
What is hemorrhagic anemia?
anemia related to severe blood loss
What is hemolytic anemia?
RBC's are destroyed and removed from the blood stream before their normal life cycle (120 days) ends
What is aplastic anemia?
the body's bone marrow doesn't produce enough new blood cells, bone marrow failure
What is hemoglobin?
protein in RBC's that carries O2
What is pernicious anemia?
the inability to process iron, lack of B12 or another intrinsic factor
What are intercalated discs?
interlocking plasma membranes in cardiac cells
What ion is used to depolarize and initiate contraction?
What ion is used to repolarize?
What ion is used in the initial threshold depolarization?
Why is cardiac muscle contract slower than skeletal muscle?
to prevent tetanic contractions
What do cardiac muscles resist?
fatigue due to the high concentration of mitochondria
What is ischemia?
What causes angina?
decreased blood flow, ST depression
Where does atherosclerosis occur?
What are autorhythmic cells?
pace the heart, pacemaker potentials, depolarize spontaneously, only carry electrical signals, do not contract
What % of cardiac cells are autorhythmic?
Describe the heart's electrical conduction.
SA node to AV node to bundle of his (AV bundle) to bundle branches to Purkinje fibers
How long is the delay at the AV node and why?
0.1s to allow atria to contract completely and ventricles to fill
What is the threshold of pacemaker potentials?
Describe the action potential in pacemaker cells.
1. pacemaker potential, initiated by slow leaking Na+ channels, -40mV threshold is met
2. depolarization, Ca+ channels open, influx of Ca+ causes contraction via troponin
3. repolarization, K+ channels open, membrane potential decreases to below threshold
What ion causes the cross bridge cycle?
Is the Ca+ intercellular or extracellular?
both, mostly extracellular
What is depolarization?
cell becomes less negative
What is repolarization?
cell becomes less positive
What ion triggers contraction?
How do calcium channel blockers affect the heart?
blocks the reuptake of Ca+, prolongs the contraction, reduces the heart rate, increases contractility
What is an ECG?
measures all action potentials generated by nodal and contractile cells at any given time
What is the normal length of a contraction cycle?
What is the contraction cycle so long?
heart needs to gain momentum for circulation
What is the P wave?
depolarization from SA node to atria
What is the normal length of a P wave?
What is a QRS complex?
What is the normal length of a QRS complex?
What is a T wave?
What is the normal length of a T wave?
What is the PQ interval?
SA node fires to AV node to bundle of his to bundle branches
How long is the PQ interval?
What does a prolonged PQ indicate? A shortened PQ?
prolonged=heart block, shortened=WPW syndrome
What is the QT interval?
time of ventricular systole, depolarization/repolarization of ventricles, ALL VENTRICLE ACTIVITY
What long is the QT interval?
What does a prolonged QT increase your risk of? What are the symptoms?
v tach, v fib, decreased heart rate, poor circulation
What is the ST segment?
the ventricles are contracting, blood is being pumped out of the heart
What does ST elevation indicate? ST depression?
ST elevation=STEMI, ST depression=angina
What part of the heart stimulates ventricular depolarization?
What regulates the cardiac system?
What does the SNS do?
cardioacceletory, increases heart rate/BP by norepinephrine/epinephrine via beta 1 receptors
What does the PSNS do?
cardioinhibitory, slows heart rate/lowers BP, innervated by the vagus nerve by ACh
What is a heart block?
disruption of the conduction between atria and ventricles, abnormal delay in PQ interval, indicates damage to the AV node
What is an ectopic focus?
area in the heart that initiates abnormal beats
What is a first degree block? Second degree block? Total heart block?
first degree-AV nodal disease, PR prolonged by .20s, second degree-1 or more but not all impulses fail, total heart block-no impulse at all
Describe an entire cardiac cycle on an ECG.
1. atrial depolarization, initiated by SA node
2. impulse delayed .1s at AV node
3. ventricular depolarization begins, causes QRS complex, atrial repolarization
4. ventricular depolarization is complete
5. ventricular repolarization occurs, causes T wave
6. ventricular repolarization is complete
What is a junctional rhythm?
non-functional SA node, AV node paces heart at 40-60bpm, no P waves
What is systole?
contractions of the ventricles, causes QRS complex, forces blood out of the heart into aorta, systolic pressure needs to exceed diastolic pressure before the blood will flow, lub sound
What is diastole?
relaxation of the ventricles
What is late diastole?
the SA node fires, the atria contracts forcing the last 20-30% of blood through the AV valves into the ventricles
What is early diastole?
SL valves shut, ventricles relax, causes T wave, blood from the aorta and pulmonary trunk flows towards the heart, dub sound
What is cardiac output? What is the average CO?
amount of blood pumped through the heart in 1 minute, 5.25L
What is the formula for CO?
CO=HR x SV
What is the constant/variables?
constant (resting) CO=output needed to maintain perfusion, variables=HR/SV
What is stroke volume? What is the average SV?
volume of blood pumped out by 1 ventricle with each beat, 70ml
What is cardiac reserve?
fluctuations in CO to meet increased demands, difference between resting and max CO, average 4-5 times resting CO, up to 7 times resting CO
How do you determine SV?
What is EDV (preload)?
end diastolic volume, amount of blood in the ventricles before contraction, degree of stretch in cardiac muscle, average EDV=120ml
What is venous return?
amount of blood returning to the heart
How do you increase venous return?
muscle contraction, deep breathing, venous valves, slow heart rate, exercise-squeezes skeletal muscle, compresses veins, decreases blood volume, returns more blood to the heart
How does an increased EDV effect the heart?
increased EDV increased how hard the heart has to contract to pump blood out
What is ESV (afterload)?
end systolic volume, volume of blood in ventricle after contraction, determined by arterial pressure and contractility, pressure the ventricles must overcome to eject blood, average ESV=50ml
What is Starlings Law?
by stretching the myocardium from the inside out, the force of contraction will be greater
How does an increased ESV effect the heart?
increases stress on the heart, heart can wear out
How can you increase/decrease contractility?
increase-aerobic exercise, digitalis, epinephrine, calcium channel blocker, decrease-MI, acidosis, potassium
What regulates the heart rate?
cardiac center of the brain, medulla oblongata
What autonomic regulation is dominant?
What are baroreceptors?
monitors pressure changes in the vessels to regulate heart rate, found in the atrial/carotid reflex
What are chemoreceptors?
monitors pH, CO2, and O2
What chemical from the thyroid weakens the heart?
thyroxine, causes a sustained increased heart rate
How do beta blockers work?
blocks beta 1 receptors
How does age affect the heart?
causes sclerosis of the valves, decline in cardiac reserve, fibrosis of the heart, atherosclerosis
What is the difference between right and left sided heart failure?
right sided is systemic, left sided is pulmonary
How does a sustained increase in DBP affect the heart?
makes is harder for blood to leave the heart, myocardium must exert more force to open AV valves
When does the fetal heart develop? When does it start beating? What is the average fetal heart rate?
during the first 3 weeks, 21 days, 140-160bpm
What are the four chambers of a fetal heart?
sinus venosus, atrium, ventricle, bulbus cordis
What are the differences in a developed fetal heart vs. adult heart?
foramen ovale becomes the fossa ovalis, ductus arteriosus becomes the ligamentum arteriosum
What do the foramen ovale and the ductus arteriosus do?
connect the 2 atria so the blood from the right side of the heart can bypass the pulmonary circuit
What are the 3 types of blood vessels?
arteries, capillaries, veins
What does the vascular system do?
exchanges gases and nutrients, removes waste
What is an artery? What is a vein?
artery-efferent, carries O2 rich blood away from the heart, vein-afferent, carries O2 poor blood towards to heart
What % of blood in the body do veins hold?
What are the 3 layers of a vessel?
tunica externa, made up of collagen, anchors vessel, tunica media, made up of smooth muscle and elastic fibers, controls blood flow in arteries, tunica intima, made up of endothelium, contains a layer of elastic lamina
What are the 4 types of arteries?
elastic, muscular, arterioles, capillaries
What are elastic arteries?
closest to the heart, able to expand and contract to keep blood moving forward
What are muscular arteries?
help to distribute and redirect the blood, branch of the elastic arteries, contain a large tunica media
What are arterioles?
mainly only tunica media and intima, leads to capillary beds
What are capillaries?
the smallest artery, only 1 tunic thick, tunica intima, forms beds where exchanges takes place
What are the 3 types of capillaries?
continuous-most common in skin and muscle, least permeable, form blood brain barrier, fenestrated-allows rapid filtration or absorption to take place, very porous, found in endocrine glands, small intestine, kidneys, sinusoidal-extremely porous, found in special organs liver, bone marrow, spleen, lymph
How are nutrients and gases exchanged?
based on concentration gradients, simple diffusion, moves from a higher pressure/concentration to a lower pressure/concentration
What is colloid osmotic pressure?
moves from lower concentration to higher concentration, pulls into the vessel, generated by concentrations of albumin and sodium
What is capillary hydrostatic pressure?
moves from higher concentration to lower concentration, "push", related to BP, increase in BP=increase in hydrostatic pressure
What is albumin?
produced by the liver, #1 plasma protein, maintains fluid balance, low albumin=edema
How do you calculate the net filtration pressure?
NFP=net hydrostatic pressure - net osmotic pressure
What are venuoles?
attach to capillaries and carry blood to the heart, very porous, allows fluid and WBC's to move in and out
What purpose do the one-way valves serve in veins?
promotes venous return to the heart, failed valves=varicose veins
What causes blood to flow? What influences it?
blood pressure, blood volume, resistance, cardiac output
What is peripheral resistance?
the back pressure the heart has to overcome to maintain blood flow, affected by viscosity, vessel length, vessel diameter
How does an increase in diameter affect peripheral resistance?
decreases peripheral resistance
What is systolic pressure? Diastolic pressure?
systolic-pressure peak from ventricular contraction (120mmHg), diastolic-lowest aortic pressure (70-80mmHg)
How do you calculate pulse pressure?
pulse pressure=systolic - diastolic
What is a mean arterial pressure? How do you calculate it?
force moving blood forward in the arteries, MAP=DBP + pulse pressure/3, need to maintain MAP at 60
What is hyperemia?
increased blood flow in a local area
What does epinephrine do?
increase heart rate, increase BP, increase contractility, vasoconstriction, blocked by beta blockers
What does atrial natriuretic peptide do?
diuretic released by heart, decreases BP, vasodilation
What does ADH do?
vasoconstriction, increase BP, increase blood volume
What are 2 short term localized chemicals?
histamine and nitric oxide
What is circulatory shock? What are the types?
widespread vasoconstriction to prevent drop in BP in vital organs, hypovolemic, cardiogenic, vascular
What side of the heart pumps blood through the pulmonary circuit?
What side of the heart pumps blood through the systemic circuit?
Describe the blood flow through the heart.
SVC/IVC to right atrium through the tricuspid valve to right ventricle through the pulmonary SL valve to the pulmonary trunk to the lungs through the pulmonary capillaries to the heart via the pulmonary veins to left atrium through the mitral valve to the left ventricle through the aortic SL valve to the aorta through the body back to the heart