lab 5

what are the 5 vital signs?

• heart rate

• body temperature

• respiratory rate

• blood pressure

• oxygen saturation

what is the resting heart rate physically determined by?

a combination of the rate at which the SA node produces action potentials and the effects of innervation by the parasympathetic nervous system (rest and digest)

on average, how many action potentials does the SA node produce per minute?

100 APs per minute = 100 beats per minute

at rest, the parasympathetic neurons send a constant stream of signals to SA node that decrease AP rate to what?

an average of 75 APs per minute = 75 beats per minute

what is the average heart rate and the range?

average is 75bpm, range is 60-100bpm

what is bradycardia?

this is when the resting heart rate is lower than 60bpm

what is tachycardia?

this is when a resting heart rate is higher than 100bpm

how does heart rate increase from exercise? in terms of SNS and SA node

the SA node gets stimulated by SNS and the endocrine system as it releases epinephrine from adrenal glands. these both act on SA node to increase heart rate by increasing the amount of APs per minute.

how do we calculate the maximum heart rate HRmax of an individual?

we do HRmax = 220 - age

heart sounds relate to what?

1. the closure of atrioventricular valves as systole begins = LUB

2. the closure of the semilunar valves as ventricular diastole begins = DUB

listening to heart sounds can provide what information?

• information on the heart’s condition and function

• diagnose heart murmurs that are a result from malfunctioning valves, holes in interventricular or interatrial septa, or other cardiac abnormalities

when listening for heart sounds, where should you place the stethoscope to hear LUB/S1?

apex of the heart, left of sternum/under breast

• occurs from turbulent blood flow caused by closure of mitral and tricuspid valves

when listening for heart sounds, where should you place the stethoscope to hear DUB/S2?

2-3 cm underneath the clavicle, left of sternum

• occurs from turbulent blood flow caused by the closure of the pulmonary and aortic semilunar valves

the contraction of cardiac muscle is initiated by what?

the conduction system of the heart

what is the conduction system composed of?

non-contractile cardiac muscle cells that have been modified to generate and spread electrical impulses.

in which atrium or ventricle can we find the SA node in?

the right atrium

how do the impulses of the SA node spread throughout the heart?

see notes

what are the 3 distinguishable waves in an ECG?

• P wave

• QRS wave

• T wave

what does ECG mean?

electrocardiogram

what are the 4 segments/intervals of an ECG?

• P-Q interval

• S-T interval/segment

• T-P interval

• R-R interval

what is the P wave?

this is atrial depolarization. SA node fires and depolarization spreads from SA node to throughout atria

what is the QRS wave?

this is ventricular depolarization. the depolarization wave spreads from AV node to the rest of the conduction system and through the ventricles.w

what is the T wave?

ventricular repolarization

what is the P-Q interval?

the start of the P wave until the start of Q wave. this represents the atria contracting and the APs spreading through the AV node

what is the S-T interval?

the end of S wave to the start of T wave. the ventricles are depolarized and contracted. blood is ejected from the ventricles into the large arteries (stroke volume)

what is the T-P interval?

this is the period of time between cardiac cycles when heart is at rest. both atria and ventricles are at rest.

what is the R-R interval?

represents the time it takes for 1 full cardiac cycle since it’s in between two R waves

what is an ECG composed of?

all of the action potentials generated by nodal and contractile cells at a given time.

what is an ECG used to assess for?

to see if the heart’s rhythm and electrical conduction is normal for a person

what are arrhythmias?

these are irregular rhythms caused by abnormal impulse formation or conduction

what are conduction delays?

these are slower than normal electrical transmission through the heart’s conduction pathways.

what is heart block?

this is a conduction delay that produces “dropped” beats because some atrial impulses (the P waves) fail to conduct through the AV node/bundle branches/pukinje fibers. this results in P waves that don’t follow QRS complexes = atria contract more than ventricles = an extra P wave

what is fibrillation?

this is uncoordinated signalling and contraction either in the atria or the ventricles. basically, a bunch of rapid irregular waves where you can’t even identify any of the waves. this is fatal if left untreated since ventricles can no longer coordinate a proper pump for blood flow

is bradycardia unhealthy?

not necessarily! this can also be a sign of excellent cardiovascular fitness. high performance athletes tend to have resting heart rates below 60bpm!

what is this

bradycardia

what is this

tachycardia

what is this

heart block

what is this

atrial fibrillation

what is this

ventricular fibrillation

how do we calculate heart rate from an electrocardiogram?

1. take chart speed and divide it by the distance between two QRS waves

2. take that value and multiply by 60

3. final value units should be beats/min

what is blood pressure used to assess for?

cardiovascular health

why is it important to maintain blood pressure?

it’s important for the proper functioning of the heart and all of the organs it supplies blood to

what is perfusion?

blood flow removing wastes

what will happen if mean arterial pressure MAP is too low?

there won’t be enough perfusion which can damage our tissues

what does blood pressure represent physiologically?

the force that blood puts on the arterial walls during contraction—systole—and relaxation—diastole—of the ventricles

where is blood pressure generally measured?

in the arteries

TRUE OR FALSE: since the heart alternates in contracting and relaxing, the blood pressure rises and falls, which is why you must take two blood pressure readings

TRUE! these are systolic and diastolic pressure

what is systolic pressure?

the pressure in the large arteries of the heart at the peak of ventricular ejection

what is diastolic pressure?

this is the pressure of large arteries during ventricular relaxation

what is hypertension?

high blood pressure. typically a value of 140/90 or higher when measured manually and 135/85 for digital instruments

what instruments do we use to measure blood pressure?

a stethoscope and a sphygmomanometer

TRUE OR FALSE: some drugs like caffeine and nicotine can cause long-term increases to blood pressure.

FALSE! they cause temporary SHORT-term increases to blood pressure. this is called acute hypertension

what is chronic hypertension?

this is when high blood pressure lasts for much longer periods and is usually associated with aging → our arteries become less elastic as we age

can also be from…

• diet rich in fat or excess salt

• lack of exercise

• stress

• some drugs and alcohol intake

what is the auscultatory method?

listening to the sounds of the body by using a stethoscope

what is blood pressure measured using?

the brachial artery since this artery is similar height/position as the large arteries exiting heart

what are the sounds of korotkoff?

this is the resumption of blood flow into the brachial artery

when using the sphygmomanometer, we inflate the cuff until what

until 160mmHg

when using the sphygmomanometer, we keep the cuff inflated for no more than?

no more than 1 minute

how do we calculate pulse pressure?

pulse pressure = systolic pressure - diastolic pressure

how do we calculate for mean arterial pressure MAP?

MAP = (1/3)(pulse pressure) + diastolic pressure

what is MAP?

the pressure of blood being delivered to organs.

what happens if MAP is too low?

if this is too low, blood may not reach the organ or may pass to slowly to have proper exchange of oxygen and nutrients and removal of wastes

what if MAP is too high?

the blood may pass through the organ too quick, not exchanging properly. it can also cause damage to the vessels of the organ

what values should MAP be?

between 70mmHg and 110mmHg