Cardiovascular System
What is the isoelectric line?
"0" on the ECG reading
What is ectopic foci?
"Competing pacemakers"; an area of the heart that is trying to set the pace that isn't the pacemaker (can be from too much caffeine or nicotine)
What are signs of CHF?
-Vein distention in neck -Fluid-filled lungs -Increased venous pressure
What influences EDV?
-length of vent filling time -effective filling pressure (r/t venous return to the heart)
What influences ESV?
-pressure in the outflow vessel (if resistance is increased, emptying of the heart decreases=ESV larger; like a milkshake, more ice cream stays in the glass) -strength of muscle contraction (drugs, sympathetics, stretch of muscle fibers)
How long does the AV node delay the electrical impulse?
0.1 second
How long is the PR interval and when is it?
0.16 seconds Beginning of P and end of isoelectric before QRS
How long is the QT interval and when is it?
0.36 seconds Beginning of QRS to end of T wave
How many seconds does each square on the ECG paper represent?
0.4 seconds
What is tachycardia?
100-180 bpm
What happens to angiotensin I after it goes to the lung?
2 aa are removed and it becomes angiotenin II
How long does it take for the angiotensinogen process to activate?
20 minutes
What is the normal heart rate?
60-100 bpm
What is the avg. pump rate of the heart?
60-70 bpm
What % of blood is in the veins?
65-75%
How much of an increase in HR occurs with each increasing degree in temp?
7-10 bpm
What volume does the heart pump?
70 ml/beat (=5L/minute)
What is the cardiac cycle?
A complete cycles of contraction and relaxation of the heart (LUB-DUB= one cycle)
Release of ANH causes what?
A lower systolic BP for 34-40 minutes
What is a functional murmur?
A murmur heard in normal individuals bc of the rapid ejection of blood into the aorta and pulmonary artery during exercise
What is a premature atrial contraction?
A slight dip right before the QRS
What causes the kidney to retain more water?
ADH
What is considered a second degree block?
AKA Wenkeback or Mobitz; when there is progressive lengthening of the PR interval (so 1:1=1 P for every QRS, 2:1= 2 P for every QRS) Considered Mobitz 1 (1:1 and 2:1) or Mobitz 2 (3:1, 4:1, etc)
Where is the only place where electrical activity crosses from atria to ventricles?
AV (Atrioventricular) Node
What all happens during LUB (S1)?
AV valve shuts Vent contracts Blood is going out of the aorta Systole (pumping)
So, when ventricles are contracted, what happens to the valves?
AV valves close SL valves open
So, when ventricles are relaxed, what happens to the valves?
AV valves open SL valves close
Where are the coronary arteries located?
Above the SL in the aorta
What do the atria do?
Act as a storage chamber/reserve for the blood waiting to go into the ventricles and is important for contraction at rapid rates
What releases aldosterone?
Adrenal Cortex
When do calcium pores open in the cells and what does this cause?
After Na has entered the cell; making plateau event for depolarization
What do calcium channel blockers do?
Allow calcium difference to build up and have stronger contractions (The channels become blocked, so the calcium is able to build up...which causes the stronger cx)
What are the SL valves and what do they do?
Aortic (between the AV valves; sep. LV from aorta) Pulmonic (furthest from the AV valves; sep. RV from pulmonary artery) One-way valves that separate the vents from arteries; When vent pressure is higher than arterial pressure (when vents contract), SLvalves open and pump blood into arteries; when vent pressure is lower than arterial pressure (when vents relax), SL valves shut
Where are the referred sounds located for the 4 valves?
Aortic: R of sternum in 2nd intercostal space Pulmonic: L of sternum in 2nd intercostal space (The aortic and pulmonic reffered sounds are heard opposite of where they are located) Tricuspid: Right of xiphoid Bicuspid/Mitral: 5th and 6th intercostal space in mid-clivicular line (left of the sternum)
When are the walls of the ventricles the same thickness?
At birth-the RV does more work in the fetus, but the LV does more work afterwards
How many chambers are in the heart, what are they, and where are they located?
At the base Right Atrium & Left Atrium At the apex Right ventricle & Left Ventricle
What are the two main categories of valves and what does one set have that the others don't?
Atrioventricular Valves (AV)- have chordae tendineae Semilunar Valves (SL)- no chordae tendineae
What competes with Ach to increase heart rate?
Atropine
Which way are arteries carrying blood?
Away from the heart (red) (arteries-away)
What is a murmur?
Backflow or turbulent blood flow heard from leaky/incompetent valves
What is bradycardia?
Below 60 bpm (Athletes may be as low as 40)
How is cardiac output changed?
By changing either the HR or the SV
How does the heart act as syncytium?
By interculated discs; all of the cells are connected electrically with the next so there is no oozing
What is systole?
CONTRACTION of the chamber
What causes the plateau for depolarization?
Calcium going into the cell
What is the functional unit of the cardiovascular system?
Capillary
What does angiotensin II do?
Causes vasoconstriction, Increases BP Increases venous return Stimulates thirst centers Causes release of aldosterone
What does Renin do?
Cleaves the angiotensin I
What are they symptoms of the initial stage of shock?
Coldy, clammy skin rapid, thready pulse dilated pupils
What is a heart block?
Damage to the AV node that results in the atria and vents beating at their own pace i.e. the atria may be 70, vents 30
What does the vagus nerve do in relation to the heart?
Decrease the HR
What happens during the preogressive stage of shock?
Decreased blood volume causeing decreased glomerular filtration rate in kidneys, loss of enzyme action in liver, general decrease in oxygen, increase in carbon dioxide and lactic acid
What is the function of the cardiovascular system?
Deliver oxygen Deliver nutrients Remove wastes Deliver hormones Contains immune cells to fight off infection
What do osmoreceptors do?
Detect increase in osmotic pressure of blood when dehydrated or low salt intake
What is the second Korotkoff sound heard when measuring blood pressure?
Diastolic BP
What is the minimum aortic pressure called and what happens?
Diastolic pressure; the SL valve is closed and the blood is still moving into the aorta away from the heart
What is used to treat myocardial vigor?
Digitalis
What decreases conduction to the AV node?
Digitalis (Dijoxin)
What placement should be avoided to hear heart sounds?
Directly over the valves bc referred sounds can be heard
What happens during S3/period of rapid filling?
Due to expansion of vents, a lower pressure is produced and blood is sucked in from the atria
When is the only time the heart has to "rest"?
During contraction
When is the period of rapid filling?
During early ventricular diastole (considered S3)
When does ventricular filling occur?
During late vent diastole when the atria contract 2/3 is from ventricles sucking 1/3 is from atrial systole
When does the contraction of the heart occur (in reference to electrical activity)?
During the plateau for depolariztion
When does most of the blood flow in the coronary arteries?
During ventricular diastole (70%; when the vents are relaxed and the SL valves are shut)
Which has a higher volume, EDV or ESV?
EDV
Does EDV or ESV vary more?
ESV
What is EDV?
End diastolic volume; The amount of blood in the heart after the vent relaxes
What is ESV?
End systolic volume; The amount of blood in the heart after the vent contracts
How do the ventricles contract?
From apex to base in a wringing motion to the right (so from top to bottom, L to R)
Where is renin released?
From the kidney (actually, the juxtaglomerular cells of the juxtamedullary apparatus)
What is the normal splitting of S2 (LUB-DUB-DUB)?
Heard on inspiraton, the ASL valve shuts before the PSL due to decreased pressure when breathing in (Heard when the aortic shuts 1st on inhalation)
What is a myocardial infarction?
Heart attack; DEATH of heart cells from no oxygen
What influences the vasomotor centers?
High centers (emotions, etc) Baroreceptors (aka mechanoreceptors, aka pressoreceptors) in aortic arch and carotid sinuses
What happens during the initial stage?
Hyposensitive; sudden BP drop, baroreceptors stimulated by decreased BP to increase SANS (HR, SV, and vasoconstriction)
Where are the osmoreceptors located?
Hypothalamus
Where are the thirst centers?
Hypothalamus
What happens during the final stage of shock?
IV fluids may restore BP before this state *If prolonged, emtabolic acidosis may occur and needs to be fixed
How do stretch receptors work if BP is increased?
If you INCREASE the BP the STRETCH RECEPTOR will send an impulse that is carried by AFFERENT signals in the VAGUS nerve to the VASOMOTOR CENTER in the brain stem that INHIBITS SANS IMPULSES. The VASOMOTOR tone is REDUCED the HR is SLOWED and there is VASODILATION (which causes you to pass out) So, increased BP ends in Vasodilation
What is resistance?
Impedance to flow caused by friction between vessel and blood
Where are baroreceptros located?
In teh aortic arch and carotid sinuses
Where is the vasomotor center located?
In the brain stem (pons and medulla)
What must happen with increased work of the heart?
Increase blood flow (increased oxygen to the heart)
What causes the heart to work harder to eject blood volume?
Increase in arterial pressure
What is pulmonary hypertension?
Increased pulmonary artery pressure and decrease in second heart sound So, the pulmonary valve shuts first during inhalation causing a reverse splitting
If CO and/or resistance is increased, what happens to BP?
Increases
If SV is increased, what happens to PP?
Increases (more filling time)
Where is the AV Node?
Inferior portion of the RA (posterior wall of the atria below the SA Node)
What does ANH do?
Inhibits Na reabsorption by kidneys, increases glomerular filtration rate of blood by kidneys by causing vasorelaxation of renal arteries, increases filtration of Na an dthus water from the blood, inhibits NE and angiotensin II effects
What are teh stages of shock?
Initial, progressive, and final
Which is longer, intervals or segments?
Intervals
How does the AV node act as a diode?
It delays the electrical impulse (for 0.1 second) to allow the atria to complete the contraction before the ventricles (acts like Christmas lights blinking)
When arteries constrict, what happens to the diastolic pressure? When they dilate what happens?
It goes up during contriction and down during dilitation
What happens during secondary shock?
It's hemorrhagic from blood/plasma loss, dehydration or edema occurs r/t lower blood volume, and the heart is inableto pump
What happens during primary shock?
It's neurogenic (syncope), sudden decrease in vasomotor tone, blood pooling It is transient and reclining helpsdecrease teh work of the heart
What happens during repolarization?
K leaves the cardiac cells to repolarize (Na and Ca is pumped out and K will get pumped back in)
What makes the lub-dub sounds?
LUB: CLOSING of AV valves DUB: CLOSING of SL valves
What is the thickest part of the heart?
LV-the wall is thicker, but the ventricle volumes are the same
Which coronary artery produces more blood flow?
Left (85%)
What is blood flow measured in?
Liters per minute
Where is angiotensinogen made?
Liver
If HR is increased, what happens to PP?
Lowers (decreased filling time)
If Resistance is increased, what happens to PP?
Lowers (not as much blood is going through)
What do the ventricles do?
Made up of spiral fibers that pump (rotate) the heart to the right
What does aldosterone do?
Make kidneys retain sodium
What is MVP?
Mitral Valve Prolapse; aka the Click murmur
Is the heart myogenic or neurogenic?
Myogenic; most areas are able to depolarize on their own
Is the cardiac output greater for the RV or the LV?
Neither, they are the same. The CO has to be equal on both sides, otherwise there is back flow causing heart failure
When is there no sympathetic tone?
Never; There is always some tone to keep vessels slightly contracted
Can the heart muscle tetanize? Why or why not?
No, bc of the long refractory period due to slow calcium channels
What is the normal sinus rhythm?
One P wave for every QRS; other than that, may be arrhythmia or irregular heart rhythm
In what ways does venous return "work"?
One-way valves, skeletal muscle pumps, abdominal-thoracic pump, cardiac suction, gravity and hydrostatic pressure
Where is ANH found?
Only in the RA
Atrial and ventricular diastole and systole work (at the same time or opposite)?
Opposite each other: So.... AV valves are opened during vent diastole AV valves are closed during vent systole
What is angina pectoris and how is it treated?
Pain in the heart r/t decreased oxygen; Is transient (reduced during rest) and treated with nitro and rest
What is the first part of the ventricles to contract?
Papillary muscles
What does the heart have that blood vessles don't?
Parasympathetics going to it
Increased temp increases what?
Plasma membrane permeability and diffusion of ions
What is a PVC?
Premature ventricular contraction; a random beat in the middle of a normal EKG
What is diastole?
Relaxation of the chamber
What does the sarcoplasmic reticulum do?
Release sequestered calcium for muscle contraction (strength depends on amt. of calcium released and it acts as all-or-none)
What is viscosity?
Resistance to flow
When does atrial contraction occur?
Right before vents contract Atria just squirts one little bit, so if the cardiac cycle is 0.8 seconds, 0.7s will be diastole (filling) and only 0.1s is systole (pumping)
Which side is systemic? Which side is pulmonic?
Right side is pulmonic-going to the lungs to become oxygenated Left side is systemic-coming from lungs and going to the other systems of the body
What is the pacemaker of the heart?
SA (sino atrial) Node in the RA near the opening of the SVC; the leakiest cells set the pace of the heart
What part of the heart depolarizes first?
SA Node (the pacemaker region)
Does teh PANS or SANS effect vessel diameter?
SANS; PANS does not go to the vessels
What all happens during DUB (S2)?
SL valve shuts Vent relaxes Pulling blood from the atrium Diastole (filling)
CO=
SVxHR
How do you control the arterial pressure long term?
Salt deprivation, Low blood volume, low oxygen, low BP
What speed does the blood flow in arterial pressure?
Slowly then increases after the blood leaves the capillaries
Where is the blood stored besides in the veins?
Spleen, liver, skin
What is the first Korotkoff sound heard when measuring blood pressure?
Systolic BP
What is the maximum aortic pressure called and what happens?
Systolic pressure; The ventricle contracts and the SL valve opens
How is pulse pressure (PP) determined?
Systolic-diastolic
What causes a systolic murmur? Diastolic? Which is more dangerous?
Systolic: insufficient AV valves Diastolic: insufficient SL valves Diastolic is more dangerous
What shows the atrial rate on an ECG?
The # of P waves per minute
What shows the ventricular rate on an ECG?
The # of QRS waves per minute
What is the AV bundle?
The Bundle of His; Modified cardiac cells that send the wave of depolarization from the AV node down the interventricular septum and separate into R and L branches
What does the P wave represent?
The DEpolarization of the atria
What does the QRS wave represent?
The DEpolarization of ventricles; also, the REpolarization of the atria is hidden here
What is an EKG showing?
The ELECTRICAL ACTIVITY of the atria (NOT the contraction of the heart!)
What maintains the resting membrane potential?
The Na:K pump
What does the T wave represent?
The REpolarization of ventricles
What determines the flow?
The ability of the heart to pump
What determines how much blood the heart can pump?
The amount of blood in venous return
What is cardiac output?
The amt. of blood pumped per min.
When oxygen in the blood decreases.....
The blood vessels in the heart dilate to bring more blood to the area that needs more oxygen
What do the chordae tendineae and papillary muscles do?
The chordae tendeneae are attached to the papillary muscles; Keep the AV valves from everting (inside-out); they contract in sync with the vents, so there is always tension on the valves
What is S4?
The contraction of the atria (the last little squirt of blood)
What is defibrillation?
The electric shock that depolarizes the entire heart to try to "reset" the SA node
What is angiotensin II?
The final product of angiotensinogen that is a powerful vasoconstrictor
What is the Frank-Starling Law of the Heart?
The heart can adjust to changes in the amount of blood returned to it (load) *If the muscle is stretched, it causes the force of the contraction to increase
What is the dicrotic notch?
The measurment artifact that appears when pressure in the aorta increases when the aortic semilunar valve shuts
What is sinus rhythm?
The pace of the heart that is determined by the SA node
What is fibrillation?
The rapid, out of phase, irregular contraction of the heart from the heart not pumping and the cells not working together; resembles a bag of worms
Which atrium has a thinner wall and why?
The right bc it has less blood coming back to it
How are vessels dilated?
The signal is stopped to the SANS
What are Korotkoff sounds?
The sounds of blood spurting through the vessels heard while measuring a blood pressure
What causes CHF?
The ventricles not being able to pump blood causing a back flow into the veins; -inadequate return of blood, increased demands on the heart, or failure of the heart r/t coronary heart disease
What is considered a complete heart block?
Third degree; when the PR ratio is greater than 8:1 (means there is NO communication between the atria and vents)
What is the vasomotor's "job"?
To continuously send sympathetic impulses
Why do you have to have high enough BP?
To filter urine, otherwise you develop toxicity
Which way are the veins carrying blood?
To the heart (blue)
Where does angiotensin I go after being cleaved by renin?
To the lung
Where do the purkinje fibers go?
To the papillary muscles for ventricular contraction
What are the AV valves and what do they do?
Tricuspid (Right) *TRI-RIGHT Bicuspid aka Mitral (Left) Separate the atria from the ventricles and allow flow through (atria to vent) and prevent it from flowing the opposite direction; when atrial pressure is higher than ventricular pressure (when vents relax), AV valves are pushed open; when the atrial pressure is lower than ventricular pressure (when vents contract), the AV valves shut
What shape does the purkinje fiber system have?
Upside down weeping willow
How do stretch receptors work if BP in decreased?
VASOMOTOR center INCREASES SANS IMPULSES, which INCREASES VIGOR OF HEART, which INCREASES HR, and causes VASOCONSTRICTION So, BP decrease ends in Vasoconstriction
If not specified, diastole and systole is referring to which type?
Ventricular
What is atrial syncytium?
When the AP travels across syncytium followed by atrial contraction (So, all the cells of the atrium act/work/move like big cell)
What is considered a first degree block?
When the PR interval is greater than 0.21
When is ANH released?
When the RA is stretched with increased BP or increased IV saline
What is incisura?
When the aortic semilunar valve shuts
When do the cardiac muscle cells depolarize?
When the membrane becomes leaky to sodium ions (So, Na is going in and K is coming out)
What is the reduced ejection phase?
When the pressure is reduced in the vent and aortic valve and the isovolumetric relaxation period is just beginning The AV valves are ABOUT to open and the SL valves are ABOUT to shut
What is the rapid ejection phase of the cardiac cycle?
When there is a rapid flow of blood into the aorta (seen through aortic pressure and vent volume)
What produces the ADH?
hypothalamus
What is pressure measured in?
mm/Hg
What releases the ADH?
posterior pituitary
Do stretch receptors work long term or short term?
short term
How much does the cardiac output increase with increased HR?
up to 2.5x
How much does the cardiac output increase with increased SV?
up to 2x
Decreased oxygen causes what to the vessles?
vasodilation; along with lower pH
What size is the heart?
~the size of an adult fist (300 g)
