Lab Final Flashcards
How many populations of cardiac myocytes does the heart have?
two
What are the populations of cardiac myocytes and what are they known as (include the percentages)
-the majority of the cell (~99%) are known as non pacemaker cells, which are regular contractile myocytes
-the remaining 1% are specialized cells known as pacemaker cells
What is the unique property of pace maker cells and what does the property do?
-they can spontaneously depolarizing and generating action potentials
-the action potentials they initiate trigger action potentials of the nonpacemaker cells
what is the stimulus for the non pacemaker cells to contract?
the action potentials that are triggered
What makes up the cardiac conduction system?
-the clusters of pace maker cells that are located in specific areas of the heart
Describe the SA node
-the SA node is located in the upper right atrium, where it acts as the main pacemaker of the heart
-it depolarizes spontaneously around 100 times per minute (BPM)
What do you have to remember about resting heart rate?
-the resting heart rate is generally lower than 100 beats per minute (BPM) due to the influence of the autonomic nervous
system
Describe the Atrioventricular Node
-located in the lower right atrium just medial to the tricuspid valve
-acts as a backup pace maker and is capable of pacing the heart at about 40 beats per minute
-conduction through the Av node is slow, producing what is known as the AV node delay
-this delay allows the atria to depolarize and contract before the ventricles which allows the ventricles to fill with blood
Describe the Purkinje system
-the impulse are transmitted from the Av node to the ventricles by the group of pacemaker cells collectively called the Purkinje system
-the myocytes of the Purkinje system pace the heart slowly but conduct impulses more rapidly than any part of the conduction system
-the Purkinje system has 3 components
What are the 3 components of the Purkinje system and describe them
-the atrioventricular (AV) bundle: a small group of fibers in the lower interatrial septum and upper interventricular septum that transmits impulses from the AV node to the ventricles
-Right and left bundle branches: impulses are transmitted from the AV bundle down either side of interventricular septum by the right and left bundle branches
Purkinje fibers: at the end of the interventricular septum, the right and left bundle branches fan out through the myocardium as the Purkinje fibers. these fibers extend about one third of the way into the heart muscle, after which they bend with regular nonpacemaker cardiac myocytes
Describe the general pathway of impulse condition through the heart
-starts with the cells in the SA node that generate an action potential
-this pacemaker action potential spreads to the non pacemaker cells of the atria and triggers them to have action potentials and contract
-the impulses are carried through the atria until they hit the AV node, where they encounter a delay
-once the Av nodal cells are depolarized this spreads to the Purkinje system and finally to the non pacemaker cardiac myocytes of the ventricles
-these cells are then trigged to depolarize and contract
-as the ventricles are repolarizing the cells of the SA node are slowly depolarizing, which begins the cycle again
-it is this process that allows for blood to be pumped throughout the heart and the body
What is important to note about ventricular depolarization and atrial repolarization
-while the ventricles are depolarizing the atria are repolarizing
Describe Electrocardiography
-known as ECG or EKG
-this is the recording of the electrical potential changes produced by depolarization and repolarization of cardiac muscle cells during the cardiac cycle
What is important when interpeting ECG
-conducting a systematic assessment
-what is the rate
-is this sinus rhythm? If not what is going on?
-are the P- waves normal?
-are the QRS complex’s normal?
-Are the ST segments normal, depressed or elevated? Quantify abnormalities
-Are the T-waves normal?
What are the ECG paper standards
-travels at 25 mm/ sec
1mm (small box)=0.04 sec
5mm (large box)=0.02 sec
What is the first way that you can determine Heart Rate
15mm/ beat * 0.4 sec/mm= 0.6 sec/ beat–> 60 sec/min/ 0.6 sec/ beat= 100 beats/min (BPM)
-in this case the 15mm comes from counting the R-R
What is the second way that you can determine Heart Rate
-the rule of 300
(300/ # of large boxes R-R)
-#of large boxes= 1, 2, 3, 4, 5, 6,
HR :300, 150, 100, 75, 60, 50
what does R-R mean
-this value is the peak (R) to the other peak (R)
what makes up one complete cycle in the ECG
1 cycle is all of the waves
-P wave, QRS complex and the T waves
what does circulatiing blood provide
-a transportation and communication system between the body’s cells and serves to maintin a relatively stable internal enviornment for optimum cellular activity
why does blood circulate( hint closed circuit)
because the heart pumps it through closed circuit of blood vessels
how does blood flow through the heart (include the direction)
-blood flow through the heart and the blood vessels is unidirectional
-flows from the heart from the pulmonary and systemic veins and out of the heart into pulmonary and systemic arteries
why is blood flow throughout the heart unidirectional
-blood flows through the chambers of the heart unidirectionally because of the action of four valves inside the heart that normally prevent retrograde or backward flow during the cardiac cycle
what are the primary pumping chambers
-the left and right ventricles
what happens to the AV and semilunar valves during ventricular diastole (relaxation) (what happens to the ventricles)
-AV valves open and semilunar valves close
-the ventricles fill with blood
what happens to the valves during ventricular systole (contraction)
-the AV valves close and the Semilunar valves open
this allows the ventricles to eject the blood into the arteries
Describe the pressure of the arteries during the cardiac cycle
-it varies
the ventricles will contract to push blood into the arterial system and then relax to fill with blood before pumping once more
-the intermittent ejection of blood into the arteries is balanced by a constant loss of blood from the arterial system through the capillaries
-when the heart pushes blood into the arteries there is a sudden increases in pressure, which slowly declines until the heart contracts again
when is BP at it’s highest
-immediatly after the ventricles contracts (systolic pressure)
when is the BP at it’s lowest
-immediately prior to the pumping of blood into the arteries (diastolic pressure)
how can systolic and diastolic pressures be measured ( this is the old mway)
-can be measured by inserting a small catheter into an artery and attaching the catheter to a pressure gauge
-this measurement is very accurate but it is invasive and often inconvenit and impractical
How is BP traditionally estimated
-you use a stethoscope and a blood pressure cuff that is connected to a mercury sphygmomanometer
-the cuff is placed on the upper arm and inflated to stop the arterial blood flow to the arm from the brachial artery
-the high pressure in the cuff collapses the artery
-the pressure in then released slowly
-when the cuff pressure begins to fall below the systolic pressure in the artery
-blood begins to flow to the arm through the partially collapsed artery
what are the Korotkoff sounds created by
-the turbulent flow of the blood because at this point the blood flow is not streamlined
when can systolic pressure be heard
-when the blood flow is first heard
when can you hear dystolic pressure
-as the cuff pressure continues to decrease and the artery regains it’s normal diamter, flow becomes streamlined and the sounds become muffled and then disappear
How do you assess blood pressure
-clean the ear pieces and the part that comes in contact with the skin
-let the subject sit for at least 5 minutes with the elbow slightly flexed
-wrap the cuff around the upper arm and support the arm at the level of the heart; align the cuff with the brachial artery
-palpate the brachial artery and place the stethoscope bell below the antecubital space over the brachial artery. place the stethoscope firmly in ears with earpieces facing toward nose
-quickly inflate the cuff pressure to 160 mm Hg or 20 mm Hg above the estimated systolic BP
-slowly release the pressure at a rate equal to 2-3 mm Hg/sec. Note the first Korotkoff sound
-continue releasing the pressure nothing when the sound becomes muffled (4th phase of diastolic BP) and when the sound disappears (5th phase diastolic BP). the 5th Korotkoff sound is the measurement used for diastolic score
-the bp is generally written 120/80 mm Hg, with the systolic score written first. occasionally, the 5th Korotkoff sound never disappears completely or it may finally diminish at a very low pressure. an accepted way to record the BP when the pressure between Korotkoff 4 and 5 is greater than 10 mm Hg is to mark it as SBP/IV-V for example 120/76-20 mm Hg
How do you know when you get the diastolic score
the needle ticks and you dont here anything anymore
Describe the blood pressure phases and Korotkoff sounds
Phase 1: first appearance of clear tapping sound; marks the SBP
Phase 2: Murmuring or swishing sounds
Phase 3: Crisper sounds increasing in intensity
Phase 4: sounds suddenly become muffled
Phase 5: sounds disappear; marks DBP
what is normal bp for adults
120/80 mm Hg
what is elevated Bp
120-129 systolic Bp
<80 diastolic
what is the stage 1 hypertension bp
130-139 systolic BP
80-89 diastolic BP
what is the stage 2 hypertension BP
> or equal to 140 systolic BP
or equal to 90 diastolic BP
Describe the hypertensive crisis BP
> 180 systolic BP
120 diastolic BP
what is needed to takes resting BP
a sphygmomanometer and a stethoscope
what does a sphygmomanometer consists of
-consists of an inflatable compression bag enclosed in an unyielding covering called the cuff, plus an inflating but, a manometer from which the pressure is read and a controlled exhaust valve to deflate the system
what is the stethoscope made of
-rubber tubing attached to a device that amplifies the sounds of blood passing through the blood vessels
what happens when the sphygmomanometer is placed around the upper arm of the patient and is inflated to a pressure above the patients systolic blood pressure and why does this happen
-there will be no sound audible
-this happens because the pressure in the cuff is high enough such that it completely occluded the blood flow
what happens if the pressure is dropped to a level equal to that of the patients systolic blood pressure
-the first Korotkoff sound will be heard
why is some blood still able to pass through the upper arm when the pressure in the artery rises during systole
-as the pressure in the cuff is the same as the pressure produced by the heart
what is turbulence the result of
the blood that is still able to pass through the upper arm flows in spurts as the pressure in the artery rises above the pressure in the cuff and then drops back down, resulting in turbulence
does turbulence have a sound
yes
what happens to the thumping sounds as the pressure of the cuff falls further
they can still be heard as long as the pressure in the cuff is between the systolic and diastolic pressures, as the arterial pressure keeps on rising above and dropping back below the pressure in the cuff
what happens to the sound as the pressure of the cuff drops all the way down
-the sounds change in quality then become muted and then disappear altogether
what happens when the pressure in the cuff drops below the diastolic blood pressure
-the cuff no longer provides any restriction to blood flow allowing the blood flow turbulence smooth again with no turbulence and thus produce no further audible sound
when would you take the BP of a patient
at different points in time and or under different circumstances (at rest vs. after exercise, etc) to see how to bloods pressure changes
what is the equation of mean arterial BP
MAP= (systolic)+ 2(diastolic)/ 3
equation for pulse pressure
pp= systolic pressure- diastolic pressure
what do endocrine glands do
they secret hormones directly into the blood
what is the purpose of secreted hormones
- to evoke a specific responses in cells/ tissues/ organs
describe negative feedback in the endocrine system and what does this achieve
-activity of the target organ acts back upon the gland and stimulates it
-this maintains homeostasis
describe the pituitary gland
-sits at the base of the skull and is often referred to as the master gland because of it’s control of the endocrine system
describe the hypothalamus
-an area of the brain immediately above the pituitary gland, controls the pituitary gland by secreting releasing hormones for each of the target organs governed by the pituitary gland
how do endocrine system diseases and disorders occur
-when one or more of the endocrine glands become dysregulated
descriube neoplasms
-these are masses
-these are the most common disease of pituitary and may cause the pituitary gland to be overactive and underactive
what can overactivity attributed to
-attributable to the functional adenoma (benign hormone secreting tumor) formed from one of the cell types of which the anterior pituitary is composed