Physiology Midterm Review

Question 1

EDV

Answer 1

End Diastolic Volume 110-120ml
Amount ventricle holds prior to contraction
Can be increased to 150-180ml

Question 2

SV

Answer 2

Stroke volume 70ml

Question 3

ESV

Answer 3

End Systolic Volume 40-50ml

Amount left over after ventricle contraction, can be as little 10-20ml

Question 4

Ejection Fraction

Answer 4

SV/EDV ex. 70/110 = 64%

Question 5

Depolarization/Contraction

Answer 5

P and QRS wave

Question 6

Repolarization

Answer 6

T wave, atrial is hidden in QRS

Question 7

P-R Interval

Answer 7

Time between firing SA node and contraction of ventricle -0.16 seconds

Question 8

Q-T Interval

Answer 8

0.35s

Ventricle contraction/depolarization

Question 9

T wave

Answer 9

Appears at end of potential

Question 10

P Wave

Answer 10

Occurs at beginning of the contraction of the atria

Question 11

Mean axis of the heart

Answer 11

59 degrees

Question 12

Large QRS cause

Answer 12

Hypertrophy of ventricle

Question 13

Depolarization

Answer 13

P and QRS waves

Question 14

Repolarization

Answer 14

T wave, atrial hidden by QRS

Question 15

AV receives signal from SA node _____s after origin

Answer 15

.03s

Question 16

Signal is delayed in the AV node for

Answer 16

.09s

Question 17

A final delay of ____s occurs in the penetrating bundles

Answer 17

.04s

Question 18

Therefore, there is a ____s delay from the initial origin of signal

Answer 18

.16s

Question 19

Sympathetic Innervation of the heart

Answer 19

Distributed to all parts of the heart, mainly the ventricle
Neurotransmitter = NE
Stimulates beta-1 adrenergic receptors
May increase permeability of fiber membranes to Sodium and Calcium

Question 20

Parasympathetic Innervation of the heart

Answer 20

Vagus mainly to the SA and AV nodes.
Decreases rate of rhythm of SA node
Increases permeability of fiber membranes to K+ ions. Hyperpolarization

Question 21

Hyperpolarization

Answer 21

-65 to -70 ml

vs -55 to -60

Question 22

Bradycardia

Answer 22

Slow rate, <60 beats/minute
Causes: Athletic heart
Vagal Stimulation
Resp rate of sinus arrhythmia - resp centers are close to cardiac centers and can spill over

Question 23

Tachycardia

Answer 23

Fast rate, >100 beats/minute
Causes: Increased body temp (increases cell activity)
Stimulation of heart by sympathetic nerves
Toxic conditions of heart ie. infection

Question 24

Dropped QRS

Answer 24

2nd degree Atrioventricular block

2:1 rhythm or variations

Question 25

Circus Movements

Answer 25

Ventricular Fibrillation - no work is done, blood sits in ventricle and heart quivers

Question 26

3 Conditions leading to Circus Movements

Answer 26

1. Pathway around circle is too long 2. Path is constant, but velocity of conduction slows down 3. The refractory period of the muscle might become greatly shortened. Can get another contraction when you shouldn't because in relative refractory, not absolute refractory

Question 27

Capacitance

Answer 27

AKA Compliance = distensibility x volume | Vascular distensibility

Question 28

Resistance

Answer 28

Impediment to blood flow in a vessel

Question 29

Resistance value if vessels strongly consticted

Answer 29

4 PRU

Question 30

PRU

Answer 30

Peripheral Resistance Unit

Question 31

Resistance value if vessels dialated

Answer 31

Falls to as little as 0.2 PRU

Question 32

Cardiac Output

Answer 32

Rate of blood flow through the entire circulatory system | 100 ml/sec

Question 33

Pressure difference from systemic arteries to systemic veins

Answer 33

100mmHg

Question 34

Resistance of entire systemic circulation =

Answer 34

100/100 or 1 PRU

Question 35

Flow

Answer 35

The greater the pressure difference, the higher the flow | The more the resistance, the slower the flow

Question 36

Blood volume

Answer 36

``` Systemic - 84% -veins 64% -arteries 13% -systemic arterioles and capillaries 7% Heart and Lungs - 16% ```

Question 37

Where is most of blood found?

Answer 37

Veins | 64%

Question 38

T Wave

Answer 38

greatest portion of ventricular mass to repolarize first is the entire outer surface of ventricles, esp near apex

Question 39

Normal T waves in 3 bipolar leads

Answer 39

Is positive, as is most of QRS

Question 40

P Wave

Answer 40

Atrial depolarization begins in sinus node | ECG normally positive in all 3 leads

Question 41

Atrial T wave

Answer 41

Slower than in ventricles Sinus node 1st part to become repolarized Almost always masked by QRS

Question 42

Mean electrical axis

Answer 42

Summation of all vectors Run neg to pos, inclined to L at 59 degrees, almost parallel to lead 2 Why lead 2 has highest peak

Question 43

Abnormal ventricular conditions that cause axis deviation

Answer 43

Change in position of heart Hypertrophy of ventricle Fluid in pericardium

Question 44

Increased Voltage

Answer 44

Sum of the voltages of all the QRS complexes of 3 leads is >4mV

Question 45

Decreased Voltage

Answer 45

Cardiac myopathies | Conditions surrounding ie. infection

Question 46

Currents of Injury

Answer 46

J point - reference point for analyzing current of injury | End of QRS

Question 47

Sinoatrial Block

Answer 47

Pacemaker not functioning/blocked Sudden cessation of P waves Resultant standstill of atria Ventricle pick up new rhythm, usually originating in AV node (slower) QRS is slowed, but not otherwise affected

Question 48

Atrioventricular Block

Answer 48

``` Conditions causing: Ischemia of AV node d/t coronary insufficiency Compression of AV bundle by scar tissue Inflammation of AV node or bundle Extreme stimulation of heart by vagus ```

Question 49

Incomplete Atrioventricular Block

Answer 49

1st degree - P-R interval > .20s 2nd degree - dropped QRS -P is present -dropped beats of ventricle 2:1 rhythm or variation

Question 50

Complete AV Block

Answer 50

No relation between rate of P waves and rate of QRS | -totally disconnected

Question 51

Paroxysmal Tachycardia

Answer 51

Heart becomes rapid in paroxysms - quick onset, rapid end | Pacemaker of heart suddenly shifts back to sinus node

Question 52

Defibrillator

Answer 52

Puts entire heart into state of absolute refractory and allows SA node to take over again and restart normal rhythm

Question 53

Laminar Flow

Answer 53

Blood flow has layers - flows at steady rate - flows in streamlines