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Physiology > REVIEW > Flashcards

REVIEW Flashcards

1
Q

Syncitium

A

All of the muscle fibers contract as one (do not act individually)

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2
Q

Fibrous insulator

A

Surrounds AV valve openings between the atria and ventricles

- helps separate contractions, so atria goes before ventricles

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3
Q

How does blood come back through the venous system?

A

Enters thru superior/inferior vena cava (carries oxygen poor blood from the body —> right atrium –> tricuspid valve (AV valve) –> right ventricle–> pulmonary valve –> pulmonary artery (off to the lungs) –> pulmonary vein (empties oxygen rich blood) –> left atrium –> mitral valve (bicuspid, left AV) –> left ventricle –> aortic valve –> aorta –> body

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4
Q

Pulmonary artery

A

Only place where deoxygenated blood is

- also occurs in the placenta for a short period of time

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5
Q

Pulmonary vein

A

Carries oxygenated blood

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6
Q

What are the semilunar valves?

A

Aortic (left) and pulmonary (right) valves

- 3 cusps (resembles Mercedes logo)

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7
Q

What are the bicuspid valves?

A

Just the mitral valve!

- has 2 triangular flaps

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8
Q

What are the tricuspid valves?

A

Right AV valve

- 3 irregular flaps

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9
Q

Where is contraction actually happening during the action potential curve?

A

The peak/plateau

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10
Q

Ventricular muscle AP

A
  • phase 0: fast Na channels open, then slow Ca channels
  • phase 1: K channels open (tip of peak)
  • phase 2: Ca channels open more (plateau)
  • phase 3: K channels open more (end of peak)
  • phase 4: resting membrane potential
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11
Q

What is the difference between conduction system and cardiomyocytes?

A

Conduction system has slow, leaky Ca channels that are not found in cardiac myocytes (just fast Na channels)

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12
Q

Systole

A

Muscle stimulated by action potential and contracting

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13
Q

Diastole

A

Muscle reestablishing Na/K/Ca gradient and is relaxing

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14
Q

EKG

A

P: atrial wave
QRS: ventricular complex
T: ventricular repolarization

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15
Q

Right atrial pressure

A

Is generally low! (located on the low pressure side)

  • diastole: blood comes in from great veins, passes thru ventricles
  • contraction does not change pressure much
  • when valves bulge back during peak of compression is the area of highest pressure
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16
Q

Ventricular pressure

A
  • diastole: raises pressure slightly

- systole: isovolumic metric pressure (volume is not changing, just pressure)

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17
Q

Ventricular pressure needs to be higher than ______ in order to eject blood into the aorta

A

Aortic pressure

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18
Q

Aortic pressure

A

Peaks with ejection peak

  • systole: aorta stretches to accomodate increase in volume
  • elastic muscle maintains pressure, does not go back to 0 until you reach diastole
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19
Q

Incisura

A

At the start of relaxation, aortic valve closes and blood runs backward in the aorta

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20
Q

Sounds of the heart

A
  • S1: AV valves close (start of systole)
  • S2: aortic/pulmonic valves close
  • S3: hear if you have watery blood splashing
  • S4: end of diastole when atria contract (not heard unless you have hypertension)
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21
Q

Ejection fraction

A

Amount of blood that comes out

  • should be around 60%
  • used to calculate cardiac output
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22
Q

Cardiac output

A

Stroke volume x heart rate

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23
Q

Frank-Starling mechanism

A

Within physiological limits, the heart pumps all the blood that comes to it without excessive damming in the veins
- extra stretch on cardiac myocytes makes actin and myosin filaments interdigitate to a more optimal degree for force generation

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24
Q

Does the Frank-Starling mechanism have a limit?

A

Yes!

- if you bring back more blood than max cardiac output, you get backflow of blood

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25
Q

If you _____ cardiac muscle, then it performs more efficiently and you have stronger contractions

A

Stretch

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26
Q

Pathway of heartbeat

A

Begins in SA node –> internodal pathway to AV node –> impulse delayed in AV node (allows atria to contract 1st) –> AV bundle takes impulse into ventricles –> left and right bundles of Purkinje fibers take impulses to all parts of ventricles

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27
Q

What is the slowest place in the conduction pathway?

A

AV node! It pierces fibrous insulator to get signal into ventricles

  • AV bundle is second slowest
  • Purkinje fibers are the fastest (have to go the farthest in the shortest amount of time)
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28
Q

Conduction system

A

Regular, spontaneous action potentials (depolarization)

  • SA node is the fastest (leakiest) to fire
  • AV node next fastest to fire
  • Purkinje fibers third fastest to fire
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29
Q

Conductance

A

Speed at which action potential is passed to the next cell

  • Purkinje fiber is the fastest
  • SA node/internodal pathways: medium speed
  • AV bundles: medium slow
  • AV node: slowest
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30
Q

Rhythmical discharge of sinus nodal fiber

A

Na leak causes resting potential to slowly increase to -40 (threshold) –> slow Ca channels open –> K channels open more –> after peak, it hits the sinus nodal fiber –> goes back to -50

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31
Q

SA node never goes as low as ______

A

Ventricular muscle fiber (will be at -80 due to specialized cells)

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32
Q

PR interval

A

Atrial depolarization

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33
Q

QT interval

A

Ventricular depolarization

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34
Q

Ventricular repolarization does not occur until ___

A

End of T wave

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35
Q

Lead 1

A

(-) right arm, (+) left arm

- looking at heart form the top down (0.5 mV)

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36
Q

Lead 2

A

(-) right arm, (+) left leg

- looking at heart from right side (1.2 mV)

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37
Q

Lead 3

A

(-) left arm, (+) left leg

- looking at heart from left side (0.7 mV)

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38
Q

First degree heart block

A

Incomplete block, AV node is slow to respond

Seen as a long space betwen P wave and QRS complex (prolonged PR interval)

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39
Q

PR interval cannot be longer than?

A

The RR input (the space between 2 heart beats)

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40
Q

Second degree heart block

A
  • PR interval increases

- atria beat faster than ventricles (dissociated)

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41
Q

Mobitz type 1 and 2

A

Associated with incomplete second degree block

  • type 1: PR gets longer with each beat until a beat is dropped
  • type 2: some impulses pass thru the AV node and some do not = dropped beats
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42
Q

Horses have a mild _______ at rest

A

Second degree block

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43
Q

Third degree complete block

A

Total block thru the AV node or AV bundle

  • P waves are completely dissociated from QRST complexes (AV dissociation)
  • ventricles escape and AV nodal rhythm ensues
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44
Q

Normal rates of discharge

A
  • sinus node: 70-80/min
  • AV node: 40-60/min
  • Purkinje: 15-40/min
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45
Q

Premature atrial contractions

A

PR interval is shortened if ectopic foci originating the beat are near the AV node –> impulse travels thru the AV node and back toward the sinus node = discharge of sinus node
- early contraction does not allow heart to fill with blood = low stroke volume and a weak radial pulse

46
Q

Premature ventricular contractions

A

QRS is prolonged because impulse is conducted thru muscle, which has slow conduction

  • QRS voltage is high because one side deoplarizes ahead of the other
  • T wave is inverted due to slow conduction = area to first depolarize is also first to repolarize (opposite of normal)
47
Q

Paroxysmal

A

Series of rapid heart beats that suddenly start and stop

  • P wave is inverted if origin is near AV node
  • occurs by re-entrant pathways
48
Q

Atrial flutter

A

Single large impulse wave travels around atria in one direction

  • atria contracts at 200-350/min
  • AV node will not pass signal until 0.35 sec elapses after the previous signal
  • atria may beat 2 or 3 times as rapidly as the ventricle
49
Q

Atrial fibrillation

A

Mostly occurs without ventricular fibrillation

  • causes by atrial enlargement due to AV valve dysfunction, results in long pathway of conduction which is favorable for circus movements
  • decreased ventricular pumping
  • irregular, fast HR due to irregular arrival of cardiac impulse at the AV node
50
Q

Ventricular fibrillation

A

Circus movements occur when pathway is too long (dilated heart), if conduction velocity is decreased, if refractory period is shortened
- some parts of ventricles contract, others relax and little blood flows out of the heart (caused by electrical shock or cardiac ischemia)

51
Q

Components of the circulation

A
  • Venous side: 60%
  • Arterial side: 20%
  • Pulmonary: 10%
52
Q

Arterioles

A

Control site for blood flow

- major resistance site of the circulation

53
Q

The _____ have the largest total cross-sectional area of the circulation

A

Capillaries!!

Followed by venules, small veins, etc

54
Q

Characteristics of blood flow

A

Usually flows in streamlines with each layer of blood remaining the same distance from the wall = laminar flow
- results in higher velocity in the center of the vessel, creating a parabolic profile

55
Q

Volume-pressure relationships in circulation

A

Any given change in volume within the arterial tree results in larger increases in blood pressure than in veins
- when veins are constricted, large quantities of blood are transferred to the heart = increased cardiac output

56
Q

Stroke volume

A

Increases in stroke volume increase pulse pressure, conversely decreases in stroke volume decrease pulse pressure

57
Q

Arterial compliance

A

Decreases in compliance increases pulse pressure, and increases in compliance decrease pulse pressure

58
Q

Capillary hydrostatic pressure

A

Force fluid outward thru the capillary membrane

59
Q

Interstitial fluid pressure

A

Opposes filtration when valve is positive

60
Q

Plasma colloid osmotic pressure

A

Opposes filtration causing osmosis of water inward thru the membrane

61
Q

Interstitial fluid colloid pressure

A

Promotes filtration by causing osmosis of fluid outward thru the membrane

62
Q

MIcrocirculation

A

Important in transport of nutrients to tissues

  • site of waste product removal
  • over 10 billion capillaries with surface area of 500-700 square meters perform function of solute and fluid exchange
  • large sphincters over metarterioles to squeeze blood down
63
Q

Net starling forces in capillaries

A

Net filtration pressure of 0.3 mmHg, which causes a net filtration rate of 2 ml/min for the entire body
- more fluid tends to leave capillaries into tissues than is returned

64
Q

Acute control of local blood flow

A

Increases in tissue metabolism lead to increases in blood flow

Decreases in oxygen availability to tissues increases tissue blood flow

2 theories: vasodialtor and oxygen lack (demand)

65
Q

Vasodilator theory

A

Increase tissue metabolism –> increase release of vasodilators –> decrease arteriole resistance –> increase blood flow

66
Q

Vasodilators

A

CO2, lactic acid, adenosine, ADP compounds, histamine, K ions, H ions
- compounds diffuse to where sphincters are located causing them to relax and increase blood flow

67
Q

Oxygen lack (demand) theory

A

Increased tissue metabolism or decreased oxygen delivery to tissues –> decreased tissue oxygen concentration –> decreased arteriole resistance –> increased blood flow

68
Q

Sympathetic innervation of blood vessels

A

Innervate all vessels except capillaries, precapillary sphincters, and some metarterioles
- innervation of small arteries/arterioles allow sympathetic nerves to increase vascular resistance

69
Q

Parasympathetic nervous system

A

Important in control of heart rate via vagus nerve

70
Q

There is more sympathetic innervation on the _____

A

Venous side

- important because this is where most residual volume is located to increase cardiac output

71
Q

Vasomotor center

A

VMC transmits impulses downward thru the cord to almost all blood vessels

  • located bilaterally in the reticular substance of the medulla and the lower third of the pons
  • composed of the vasoconstrictor area, vasodilator area, and sensory area
72
Q

Anatomy of baroreceptors

A

Spray type nerve endings located in the walls of the carotid bifurcation called the carotid sinus and in the walls of the aortic arch

73
Q

Signals from carotid sinus

A

Transmitted by Hering’s nerve to the glossopharyngeal nerves and then to the nucleus tractus solitarius of the medulla

74
Q

Signals from the arch of the aorta

A

Transmitted thru the vagus into the NTS

75
Q

Chemoreceptors

A

Chemosensitive cells sensitive to oxygen lack, CO2 excess, or H ion excess

  • located in carotid bodies near the carotid bifurcation and on the arch of the aorta
  • activation = excitation of the VMC
  • not stimulated until pressure falls below 80 mmHg
76
Q

Chemoreceptor activation

A

Decreased O2, increased CO2, or decreased pH –> chemoreceptors –> VMC –> increase sympathetic activity –> increase blood pressure

77
Q

Effect of ECFV on arterial pressure

A

Increased ECFV –> increased blood volume –> increased mean circulatory filling pressure –> increased venous return of blood to the heart –> increased CO –> could stimulate increased arterial pressure directly, OR –> autoregulation –> increased total peripheral resistance

78
Q

Where is renin made?

A

Renin is synthesized and stored in modified smooth muscle cells (juxtaglomerular cells) in afferent arterioles of the kidney

79
Q

Renin is released in response to _____

A

Fall in arterial pressure

- acts on a plasma globulin called angiotensinogen to form angiotensin 1

80
Q

A1

A

Converted to A2 by a converting enzyme (ACE) located in endothelial cells in the pulmonary circulation

81
Q

Renin-Angiotensin System

A

Decreased arterial pressure –> renin –> renin substrate (angiotensinogen) –> angiotensin 1 –> converting enzyme (lung) –> angiotensin 2 –> renal retention of Na and H2O, vasoconstriction = increased arterial pressure, OR A2 is inactivated by agniotensinase

82
Q

Sympathetic regulation of the circulation (exercise)

A 
Brain and coronary has little effect
- skin is dialated by temp
- constriction of splanchnic and renal
- non exercised muscle is constricted
= increased leg flow during exercise
*vasodilation overcomes sympathetic*
83
Q

Coronary flow

A

225 ml/min

  • epicardial vessels: can see on the outside of the heart
  • subendocardial vessles: located on endocardial surface, interdigitae, is under the most pressure
84
Q

Right and left coronary arteries

A

Come off the base of the aorta

- epicardial vessels wrap around the heart to supply the muscle

85
Q

Changes in subendocardial coronary flow during the cardiac cycle

A

Subendocardial decreases drastically during systole, followed by rapid increase and hyperincrease at the start of diastole that evens out back to normal
- area under the most pressure!

86
Q

Changes in epicardial flow during the cardiac cycle

A

Slight decrease at the beginning of systole, but quickly recovers by diastole

87
Q

Immediate depressed pumping ability caused by acute moderate heart failure

A
  • reduced cardiac output
  • back up of venous return
  • activates reflexes baroreceptor + chemoreceptor
  • if severe: CNS ischemic response
88
Q

Immediate compensation caused by acute moderate heart failure

A
  • reflexes stimulate sympathetic response
  • remaining normal cardiac muscle pumps harder
  • maximum by 30 sec post- insult
89
Q

Chronic responses to cardiac failure

A
  • renal Na and H2O retention
  • cardiac recovery (repair of muscle)
  • ANP (atrial natriuretic peptide) = extra Na secreation
90
Q

ANP

A
  • normal C.O.
  • RAP (right atrial pressure increased)
  • resting HR increased
  • air hunger/exercise intolerance
  • weight gain from fluid retention
  • reduced cardiac reserve
91
Q

Progressive shock

A

Occurs 30 min after hemorrhage, will recover if given a transfusion around 60 min post-insult

92
Q

Irreversible shock

A

Occurs during progressive stage if transfusion is not given

- happens 60-90 min post-insult

93
Q

In fetal circulation ______ is higher than ______

A

Right atrial pressure; left atrial pressure

94
Q

Ductus arteriosus

A

Shunt from pulmonary artery to aorta; also right to left shunt

95
Q

Foramen ovale

A

Shunt from right to left atrium

  • oval hole in the septum
  • blood with highest O2 content to left ventricle to supply carotid and brain
  • flow across about 1/2 cardiac output (300 ml/min/kg)
96
Q

What are the 2 bypasses for the lungs in the fetal heart?

A

Foramen ovale and ductus arteriosus

97
Q

What is the 2nd place in the arterial system that carries unoxygenated blood?

A

Umbilical arteries

98
Q

1st heart sound (S1)

A

Lub

  • AV valves close (mitral and tricuspid)
  • lounder than S2
  • low pitch
99
Q

2nd heart sound

A

Dup

- aortic and pulmonary valves close

100
Q

3rd heart sound

A
  • low pitch

- caused by inrushing of blood into ventricles

101
Q

4th heart sound

A
  • atrial contraction late in diastole

- hard to hear with stethoscope, except in hypertensive patients with a thick left ventricle

102
Q

Heart sounds heard on the left side of the body

A

PAM

- pulmonary, aortic, mitral

103
Q

Heart sounds heard on the right side of the body

A

Tricuspid valve

104
Q

You want to listen for ____ and ____ when grading murmurs

A 
Timming
- systolic/pan or holo
- diastolic/ pan or holo
- continuous
- crescendo-decrescendo
Loudness
- grade 1-5 scale, or 1-6 scale
105
Q

Grading murmurs

A
  • point of maximal intensity (where the murmur is heard the loudest
  • cardiac thrill
  • low viscosity murmur due to anemia
  • acquired vs congenital
106
Q

Causes of murmurs

A
  • stenosis: narrowing

- insufficiency: not sealing, leaky (regurgitation)

107
Q

Congenital murmurs

A

Failure of heart formation during gestation

  • patent ductus arteriosus
  • interventricular septal defect
  • interatrial septal defect
  • tetralogy of fallot (have all 4)
108
Q

Blood tissue barriers

A

Depend on structure of endothelial wall

  • highly fenestrated: many compounds pass (liver)
  • specific filtration (kidney glomerulus)
  • very tight junctions: limited passage, only small molecules (brain)
109
Q

What molecules pass thru the BBB?

A
  • O2, CO2, Na, etc
  • NO: proteins, drugs
  • must pass thru pinocytotic vesicles
110
Q

Cerebrospinal fluid flow

A

Choroid plexus in lateral ventircles –> foramen of Monro to 3rd ventricle –> aqueduct of Sylvius –> 4th ventricle –> foraminal of Magendie and Luschka –> subarachnoid space over brain and spinal cord –> reabsorption into venous sinus blood via arachnoid villi

Physiology (33 decks)

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