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Med Physiology Certificate > Muscle and Cardiovascular System > Flashcards

Muscle and Cardiovascular System Flashcards

1
Q

What unit is made up of multiple myofibrils in muscle?

A

Muscle fiber

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2
Q

What is the smallest unit of the muscle (not including sarcomere)

A

Myofilament

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3
Q

What unit is made up of multiple muscle fibers?

A

Fascicle

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4
Q

What is the difference between the sarcolemma and the endomysium?

A

Sarcolemma: membrane surrounding muscle cell/fiber
Endomysium: CONNECTIVE tissue surrounding muscle cell/fiber

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5
Q

List the connective tissues that separate each unit of muscle from innermost to outermost

A

Endomysium surrounds muscle fiber/cell
Perimysium surrounds fascicle (muscle bundles)
Epimysium surrounds muscle

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6
Q

Where are the myonuclei and satellite cells found?

A

Sarcolemma, membrane surrounding muscle fibers

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7
Q

How do skeletal muscles contract or relax in uniform?

A

1.) Organization in series or parallel
2.) Connective tissue surrounding each component of a muscle come together to form the tendon that connects to bone
3.)

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8
Q

What is the main purpose of the sarcoplasmic reticulum in skeletal muscle?

A

Store protein and calcium

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9
Q

What area of the sarcomere marks the beginning and end of a unit

A

Z disk

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10
Q

What parts of the sarcomere make up the I band?

A

Thin filament, Titin, Z disk

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11
Q

What does the A band consist of

A

Think and thin filaments only (middle of the sarcomere)

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12
Q

What does the H zone consist of?

A

Where the Think filament has no barbs, spans between the M line of a sarcomere

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13
Q

What does the M line consist of?

A

Middle and thick filaments

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14
Q

What zone of the sarcomere “disappears” during contraction and why?

A

The H band disappears due to the thin and thick filaments moving towards the M line there is no place where the portion of the thick filament has barbless area exposed. Thin filaments cover the H zone

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15
Q

Describe the sarcoplasmic reticulum and where its located

A

Membranous, smooth ER
Surrounds each muscle fiber/cell

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16
Q

True/False: the sarcolemma and sarcoplasmic reticulum are synonomous

A

False, the sarcolemma surrounds each muscle fiber
The sarcoplasmic reticulum webs around each muscle sarcomeres and myofibrils

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17
Q

What does the triad consist of?

A

Consists of the sarcoplasmic reticulum and T tubules

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18
Q

What two types of receptors are found in the triad?

A

Dihydropyridine receptors
Ryanodine receptors

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19
Q

What do Dihydropyridine receptors do?

A

Voltage sensors

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20
Q

What do ryanodine receptors do?

A

Calcium release channel

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21
Q

What are the two components that make up a thick filament

A

Myosin and titin

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22
Q

List the 7 components of a thin filament

A

Actin
Troponin
Tropomyosin
Nebulin
Tropomodulin
α-Actinin
CapZ protein

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23
Q

What does Desmin do?

A

Attaches neighboring sarcomeres or sarcolemma

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24
Q

___________ __________ are the motor units responsible for movement across thin filaments

A

Myosin heads

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25
Q

What is the purpose of titin?

A

Tethers myosin filaments to the Z line

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26
Q

What does the Tropomyosin do?

A

Covers the active site of the troponin complex

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27
Q

What does Nebulin do in the thin filament?

A

Protein that sets the length filament at the Z line

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28
Q

What does CapZ do?

A

Helps anchor thin filament, actin, to the Z line

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29
Q

What does Tropomodulin do?

A

In thin filament, found towards center of the sarcomere on the end of the actin filament
Regulates length

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30
Q

Thin filament is composed of tropomyosin and troponin complexes. What are the supporting units?

A

Filamentous actin compose another portion of the thin filament. Filamentous actin is made up of Globular actin

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31
Q

CapZ is known to help anchor tin filaments to Z line. What other component assists in anchoring actin to Z line?

A

α-Actinin

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32
Q

What do desmin and Dystrophin do on a broad scale?

A

Anchor sarcomeres to sarcolemma

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33
Q

What does Desmin do?

A

Binds thin filament to Z disk
Interacts with α-Actinin and integrates to anchor Z disk to sarcolemma

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34
Q

What does Dystrophin do?

A

Large structural protein that connects sarcomeres to sarcolemma & is important for stabilization of sarcolemma to prevent damage during contraction a

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35
Q

In each thick filament, there are 2 heavy chains wrapped together in an α-helix. Describe what the essential light chain and regulatory light chain does.

A

Essential light chain: breaks ATP into ADP and Phosphate, ATP-ase activity
Regulatory Light chain: phosphorylated to promote interaction with thin filament

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36
Q

When myofibrils are arranged in Parallel (one one top of the other) what can this indicate about the function?

A

Movement of the muscle will be advantage in speed, high velocity and quick action

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37
Q

Why are myofibrils that are arranged in parallel “Faster”?

A

They have greater maximum unloaded displacement. While contraction time remains the same for series and parallel arrangement, if displacement is changed, D*T=Velocity

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38
Q

When myofibrils are arranged in series (right next to each other sequentially) what can this indicate about the function?

A

Movement of muscle will be advantaged in strength

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39
Q

Why are myofibrils arranged in series greater strength ability?

A

Because they have greater maximal tension

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40
Q

There are three potential actions during muscle contraction: 1.) Shortening
2.) Lengthening
3.) _______________

A

Isometric

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41
Q

What is and where is the sarcoplasmic reticulum

A

Surrounds the sarcomeres throughout the myofibril and stores Calcium

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42
Q

What do the T-tubules (Transverse tubule) do and where are they found?

A

Continuation of the sarcolemma into the sarcomeres to allow for communication of innermost muscle cell to outermost

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43
Q

When sarcomeres contract, what is happening?

A

The sarcomere is shortening, the thick filaments are pulling the thin filaments to overlap the thick filaments towards the M line. Z line moving towards each other

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44
Q

From where to T-tubules come from and how to they communicate?

A

T-tubules are an invagination of the sarcolemma surrounding the myofibrils that allows communication into the sarcomere

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45
Q

What does DHPR do and where is it found?

A

Senses when an action potential is moving along T tubule Found in the T tubule in the triad

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46
Q

Where is the RyR found and what does it do?

A

In the sarcoplasmic reticulum of the triad that is a calcium release channel

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47
Q

What are the 4 components of force modulation?

A

1.) Twitch to Tetanus
2.) Neural feed back
3.) Mechanical length
4.) Speed

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48
Q

When muscle fibers are aligned in same direction as origin and insertion in parallel:

A

All muscle fibers and sarcomeres are aligned in same direction as force production

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49
Q

What are pennate muscles?

A

When muscle fibers/cells are NOT arranged in same direction of force production, aligned at an angle of force production

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50
Q

Describe the arrangement of the unipennate muscle.

A

The muscle fibers are all aligned in same direction, BUT at an angle with respect to direction of force production

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51
Q

Describe the arrangement of the bipennate muscle

A

Muscle fiber/cell orientation exists with 2 different angles with respect to direction of force production

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52
Q

What is the purpose of having pennate muscle fiber arrangement?

A

Allows more myofibrils to be compacted into a muscles that amplifies muscle strength
Limits length of contraction

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53
Q

Pennation produces: 1.)
2.)
3.)

A

Working range
Optimal length
Maximal force

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54
Q

Muscles that are optimized for force production will have what type of pennation angles

A

Multiple different pennation angles

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55
Q

What is happening to the sarcomere during shortening muscle action?

A

Sarcomeres are shortening

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56
Q

What is happening in an isotonic muscle shortening?

A

Shortening against fixed load

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57
Q

What is happening during isometric muscle action?

A

Myosin heads are cycling, not length change rather force production
ie. pulling on rope tied to a tree, with more pull there is higher tension

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58
Q

What is happening during lengthening muscle action?

A

The myosin heads are trying to pull the thin filaments towards the center but opposing force is to great to overcome. Actin filaments of thin filaments are being pulled apart that can cause injury due to excess strain

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59
Q

Changing the stimulus rate in force modulation of muscles is AKA:
1.)
2.)

A

1.) Temporal coding/summation
2.) Twitch-tetanus switching

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60
Q

A stimulus frequency of muscle that allows for complete contraction and relaxation is known as:

A

Isometric contraction that creates tension
Twitch

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61
Q

When stimulus frequency is increased, what happens to muscle?
This is known as:
1.)

A

There is greater force production with each stimulus as the muscle is not able to completely relax before contracting again
Temporal summation

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62
Q

Past temporal summation (increased frequency generating doubled force), there is unfused tetanus. What is happening?

A

Rapid rise in force production & some slight recovery between contractions because some Ca+ requesting allowed with overall plateau

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63
Q

What is fused tetanus?

A

The fastest frequency stimulation with great force production that plateaus, constant contraction, does not allow any Ca+ resequestering, so tension is constant

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64
Q

Different isozymes in muscles can impact the phenotype of muscles. How does this relate to Fast-twitch and Slow twitch muscles and temporal summation?

A

Fast twitch muscles tetanize at lower stimulation frequency compared to fast twitch muscles that tetanize at higher frequency
This allows for longer duration of contraction of slow fibers compared to fast twitch muscles that generate greater forces and higher speed of contraction

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65
Q

What is the physiological difference between slow twitch and fast twitch muscles

A

Fast twitch have large diameter and have greater quantity of fiber motor units compared to slow twitch
Different isozymes of light and heavy chains, and SERCA

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66
Q

Where do neurons from the CNS attach to the muscle and tendon?

A

Muscle: muscle spindles/intrafusal fibers
Tendon: golgi tendon organs
Both providing communication to and from CNS

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67
Q

What do muscle spindles do?

A

Run parallel to muscle fibers and assess the degree of stretch and speed of contraction

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68
Q

What do golgi tendon organs do?

A

They detect the tension exerted by muscle

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69
Q

A single motor neuron innervates ___ sets of:

A

1 set of muscle fibers that respond based on activation history

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70
Q

Fast twitch muscles are going to contain large stores of phosphocreatine and glycogen. Why?

A

Because these can be used in anaerobic metabolism for APT synthesis during short and fast muscle activity

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71
Q

Why are there larger stores of glucose, fatty acid and amino acids in slow twitch muscles?

A

They can be used in aerobic metabolism for APT synthesis which is more sustainable energy source

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72
Q

What type of motor neuron recruitment threshold would be associated with fast twitch muscles?

A

High, when trying to gauge highest level of force production

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73
Q

What type of motor neuron recruitment threshold would be associated with slow twitch muscles

A

Low since they will be more chronically active

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74
Q

T/F: muscles either have oxidative or glycolytic metabolism.

A

False. some fast twitch muscles have capability for both
Type IIa for example has both

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75
Q

Slow twitch muscles are AKA

A

Type I

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76
Q

Fast twitch muscles are AKA

A

Type II a & Type II b

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77
Q

Type IIb muscles are white in appearance and have fewer mitochondria, why?

A

Because they rely purely on oxidative metabolism which does not require mitochondria and are white due to low myoglobin

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78
Q

What is the difference between spatial summation and temporal summation for muscles?

A

Spatial summation: gradual recruitment of more and more motor units
Temporal summation: twitch vs. tetanus based on increased frequency

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79
Q

At low intensity, ________ twitch fibers are recruited. As intensity increases, _____________ fibers then _______ fibers are recruited. This is known as:

A

Slow twitch
Type II A units
Type II B units
Henneman size principle

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80
Q

Describe the difference between temporal summation and spatial summation in terms

A

Spatial summation: starting with the smallest motor units, progressively larger units are recruited with increasing strength of muscle contraction allow smooth increase in muscle strength with Type IIb units active at relatively high force output
Temporal summation: rate of stimulation is modified to increase force production, moving from twitch to tetanus

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81
Q

When measuring tension at a given muscle length, the contraction is considered:

A

Isometric

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82
Q

What is L₀?

A

The length where optimal overlap of thin and thick filament occurs and sarcomere is generating optimal force

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83
Q

What are the passive components of tension force? What do they do?

A

Part of the sarcomere that is not engaging in active cross bridge cycling
These passive components generate exponential force as muscle is stretched important counterbalance to active components of force

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84
Q

In an isometric contraction, the __________ forces are generated where there is no change in length. Explain what is happening on the sarcomere

A

Highest
Here the myosin heads are generating force by attaching and reattaching on similar areas, since there is no change in length the force generated is tension

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85
Q

The highest rate of muscle shortening occurs when?
Explain what is happening on the sarcomere

A

There there is no opposing load/force so velocity is greatest
Here since the length is changing, the myosin heads are allowed to slide and change with no resisting forces and fast

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86
Q

What is special about the myosin heavy chain isoforms on fast twitch muscles?

A

They are much faster in shortening via cross bridge cycling the sarcomere, thus contract faster

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87
Q

Where does maximal power occur on muscles generally speaking?
When considering a mix of slow and fast twitch fibers, where does maximal power occur?

A

When there is intermediate load,
When velocity is half maximal

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88
Q

High power fiber outputs are done by:

A

Fast twitch fibers because they have greatest velocity but use a lot of ATP

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89
Q

Low power fiber outputs are done by:

A

Slow twitch fibers that have optimal power at lower velocity but are sustainable

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90
Q

If there is no “load” on a muscle, what does that mean?

A

There is no opposing force that prevents the myosin heavy chain from pulling thin filament towards M line

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91
Q
A
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92
Q

Power= ____/_____ OR ___f x ____

A

Work/time or Force x velocity

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93
Q

Eccentric contractions are:

A

Lengthening

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94
Q

What are the two most basic type of skeletal muscle fibers?

A

Fast and slow twitch

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95
Q

What is a major component of cardiac myofibers that differs from skeletal myofilament

A

Intercalated disks separates fibers, butmyofibers at in SYNCITIUM

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96
Q

What physically connects cardiac myofibers to one another?

A

Desmosome

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97
Q

What electrically connects each cardiac myofiber to one another?

A

Gap junctions aka Connexons

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98
Q

T/F: Since sarcomeres are the same in cardiac and skeletal muscle, then both have the same composition of T-tubule and sarcoplasmic reticulum

A

False, the cardiac muscle T tubules and sarcoplasmic reticulum aren’t as developed compared to skeletal muscle
Cardiac muscle T-tubule forms Dyad instead of triad

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99
Q

T/F: Skeletal and cardiac muscle have the same quantity of mitochondria due to the high energy requirement

A

False, cardiac requires more and has more mitochondria and uses more ATP since they are constantly working

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100
Q

Cardiomyocytes rely heavily on the oxidation of _______ for functioning

A

Fats

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101
Q

What component of cardiac muscle that allows for coordinated myofiber movmement?

A

Gap junctions

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102
Q

Describe the depolarization and refractory period of Guinea pig atrium

A

1.) There is fast depolarization to activate cell
2.) The absolute refractory period is long which disallows repeated simulation of the heart

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103
Q

What does phospholambin do?

A

Inhibits CERCA to disallow pulling Ca+ back into the cell for contraction

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104
Q

What is the difference between cardiac muscle & skeletal muscle in terms of Ca+ stores and why is it important

A

Cardiac muscle not only relys on internal Ca+ supply but also extracellular calcium via DHPR channel and Na/Ca+2 pump. This gives cardiac muscle extra reserves to elicit maximal contraction

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105
Q

What is the difference between skeletal muscle and cardiac muscle in terms of the DHPR and RyR channel?

A

Skeletal: DHPR and RyR channel are directly connected
Cardiac muscle: DHPR and RyR channel not directly connected

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106
Q

Explain how the action potential reaching the DHPR effects skeletal muscle.

A

Electromechanical coupling: DHPR changes conformation when AP stimulates which results in mechanical change/opening of ryanodine release channel inside muscle to allow release of Ca+ from the sarcoplasmic reticulum

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107
Q

Explain the Electrochemical coupling of Ryr and DHPR channels in cardiac muscle:

A

Electrochemical coupling: DHPR is activated after action potential, the permeability to Ca+2 is increased and extracellular calcium flows in through the DHPR pore and diffuses to the RyR channel
The extracellular Ca+2 signals the RyR to release Ca+2 from sarcoplasmic reticulum

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108
Q

RyR and DHPR action:
Cardiac muscle: ____________ coupling
Skeletal muscle: _______________ coupling

A

Electrochemical coupling
Electromechanical coupling & directly connected

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109
Q

Name an L-type calcium channel

A

DHPR

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110
Q

The electrochemical coupling of cardiac muscle in terms of DHPR and RyR is also known as:

A

Calcium-induced calcium release due to the extracellular calcium inducing release of calcium stores into cell

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111
Q

T/F: Skeletal muscle requires extracellular Ca+2

A

False, cardiac muscle requires external calcium

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112
Q

What happens if you place skeletal muscle in Ringers solution (solution heavy in Ca+2)? What about cardiac muslce?

A

In skeletal muscle, nothing since it does not rely on external calcium
In cardiac muscle, it can induce contraction since the external Ca+2 induces release of Ca+2 from RyR

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113
Q

Isometric force is AKA

A

Tension, since there is no change in length but the myosin heads are still contracting

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114
Q

What is active force?

A

The force generated by cross bridge cycling where there is maximum active tension

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115
Q

Compare passive force vs active force in cardiac muscle

A

Passive force: high and exponential
Active force: narrow where peak force is not symmetric, once beyond a certain sarcomere length there is a sharp drop in active force production

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116
Q

What happens to force type in skeletal muscle when stretch sarcomere length past approx 2.7 mm?

A

The passive force increases exponentially due to muscle starting to pull back and counter act the force pulling sarcomere apart

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117
Q

In terms of length, what is a major difference between skeletal and cardiac muscle active force?

A

The skeletal muscle has a much wider length at which there is active force (1.4-2.8 um) compared to cardiac where active force is greatest about 2.4 mm on a scale of 1.9-2.6 um

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118
Q

What type of force is being produced in cardiac muscle during diastole?

A

Passive force as heart is passively filling with blood while the filling is spacing out the sarcomeres creating tension for muscle to oppose

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119
Q

What type of force is being produced in cardiac muscle during systole?

A

Active force as heart is shortening and contracting sarcomere length and getting shorter

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120
Q

Preload is AKA

A

End Diastolic Volume

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121
Q

What is End Diastolic Volume?

A

Heart is filled with blood and waiting to contract

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122
Q

What is the isometric phase in cardiac cycle?

A

Preload, the force that must be overcome before ejecting blood from the ventricle during systole

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123
Q

What is the isotonic phase of cardiac cycle?

A

Afterload, the force required to expel the blood opposes the preload

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124
Q

At a given preload, the velocity of shortening for cardiac muscle becomes ____________ with lower ________ _______( __________ __________)

A

Greater
After load (opposing force)

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125
Q

At a given after load: the velocity of shortening cardiac muscle becomes _____________ with a greater _____________

A

greater
preload

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126
Q

Where does actin linked regulation occur?

A

Cardiac muscle

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127
Q

Why does cardiac muscle use actin-linked regulation?

A

Because a single action potential does not result in maximal force due to cardiac myocytes not having large stores of Ca internally
But can reserve Ca is external is given to increase force production

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128
Q

Define contractility:

A

Change in force at a given sarcomere length

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129
Q

What do ionotropic agents do?

A

Affect contractility of cardiac muscle

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130
Q

What do positive ionotropic agents do?

A

Increase Ca in cardiac muscle, inc Contractility
1.) opening Ca channels
2.) inhibiting Na/Ca exchange
3.) Changing Ca stores
4.) Inhibiting Ca pump

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131
Q

What do negative ionotropic agents do?

A

Decrease Ca in Cardiac muscle, decrease contractility
1.) Ca channel blowers
2.) lowered Ca
3.) Higher extracellular Na

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132
Q

During preload: Increasing contractility will, increase __________ force and:

A

Active force
total force

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133
Q

During afterload: increasing contractility will _____________ velocity

A

Increase

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134
Q

What is the basic mechanism of terminating muscle contraction

A

Re-Sequestering Ca by SERCA into the sarcoplasmic reticulum

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135
Q

In cardiac muscle, terminating contraction, what role does phospholamban play?

A

Inhibits calcium pump

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136
Q

Which valve connects the Right atrium and Right ventricle

A

Tricuspid

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137
Q

The left heart supplies what?

A

The systemic circuit

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138
Q

The right heart supplies what?

A

The pulmonary circulation

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139
Q

What connects the L atrium and L ventricle?

A

Mitral valve (bicuspid)

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140
Q

Where is the pulmonic valve found?

A

Between the Right ventricle and pulmonary artery

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141
Q

Where is the aortic valve found?

A

Between the Left ventricle and aorta

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142
Q

List the 5 requirements of effective heart operation

A

1.) Contraction at regular intervals and synchronous (no arrythmia)
2.) Valves must fully open (not stenotic)
3.) Valves may not leave ( no regurgitation)
4.) Contractions must be forceful
5.) Ventricles adequately fill during diastole

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143
Q

When discussing diastole and systole, what part of the heart is being referred to?

A

Ventricles

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144
Q

Why is the heart considered a dual pump?

A

2 sided, one supplying systemic circulation, the other supplying pulmonary circulation

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145
Q

The systemic circulation is linked in __________ with the left heart pump

A

Series

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146
Q

The pulmonary circulation is link in ____________ with the right heart pump

A

Series

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147
Q

The systemic circulation can change the amount of blood flowing to a body system based on its need. I.e. during exercise, skeletal muscle will receive more blood than GI system. This is all due to:

A

The systemic circulation disseminates blood via parallel arrangement

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148
Q

Resistance in series is:

A

Summative
Rtotal= R1 + R2 + R3 + etc.

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149
Q

Resistance in parallel is:

A

Inverse of total resistance
1/R total = 1/R1 + 1/R2 + 1/R3

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150
Q

How does the systemic circulation arrangement allow for independent relation of blood flow to each organ?

A

Parallel arrangement
Total peripheral resistance does not change when organ systems increase/decrease blood flow to an individual portion

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151
Q

List 7 parameters affecting hemodynamics

A

1.) Individual blood vessel diameter
2.) Mean blood flow velocity
3.) Total cross sectional area
4.) Blood volume distribution
5.) Total peripheral resistance
6.) Mean blood pressure

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152
Q
A
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153
Q

Where is the largest total cross sectional area found?

A

Capillary

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154
Q

Where is blood flow velocity greatest?

A

Aorta

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155
Q

Why is velocity slow at the capillary?

A

Slowed down for exchange of nutrients, waste and gases

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156
Q

Where is mean blood pressure highest?

A

Aorta

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157
Q

In circulatory system, as the total cross sectional area gets larger, the velocity:

A

Gets Smaller/slower

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158
Q

What physical changes can be made to reduce resistance in vessels

A

Increase vessel diameter, and vice versa

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159
Q

Where is the lowest resistance in circulatory system?

A

In capillary

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160
Q

Where is the greatest residual resistance found?
What is happening?

A

Arterioles
As blood exits the arterioles, the expansive network of parallel capillaries allows drop in resistance

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161
Q

At rest, low pressure __________ contain the majority of the systemic blood volume and called the ______________vessels

A

Vessels
Capacitance vessels

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162
Q

What is transmural pressure?

A

The pressure difference across a blood vessel wall. The blood exerting pressure from the lumen (internal pressure, Pi) and pressure being exerted from outside the vesssel (Po)

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163
Q

How is Transmural pressure calculated?

A

Transmural pressure= Pi-Po
Inside pressure of vessel - pressure being exerted on pressure

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164
Q

Why is transmural pressure important?

A

Influences vessel diameter
The pressure that is being measured by a cuff

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165
Q

What is the driving pressure?

A

The pressure driving blood flow from HIGH to LOW pressure

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166
Q

What must occur for driving pressure to occur?

A

P2 must be lower than P1 to allow flow from high pressure to low pressure

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167
Q

Ow do you calculate Driving Pressure?

A

Delta P = P1-P2

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168
Q

If calculating Delta P (__________ __________), what would be P1? P2?

A

Driving pressure
P1: Aorta
P2: Right Atrium, ~2 mmHg

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169
Q

If calculating Delta P in pulmonary system ( ________ ____________) what would be P1? P2?

A

Driving pressure
P1: R ventricle
P2: Left atrial pressure ~ 7 mmHg

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170
Q

What is the mean pressure of the arteries in systemic circulation?

A

100 mmHg

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171
Q

What is the mean arterial pressure of Arteries in pulmonary circuit?

A

15 mmHg

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172
Q

To calculate driving pressure of systemic circuit and pulmonary circuit, what 2 numbers are needed respectively?

A

Need Mean arterial pressure for systemic and pulmonary circuit, P1

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173
Q

What does the term phasic blood pressure mean in the aorta?

A

The change of pressure during systole versus diastole

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174
Q

What are the 2 ways to calculate mean arterial pressure?

A

MAP=1/3 systolic P + 2/3 diastolic pressure
MAP= Diastolic pressure + 1/3 Pulse pressure

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175
Q

How is Pulse pressure calculated?

A

Systolic pressure-diastolic pressure

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176
Q

How do you calculate systemic driving pressure?

A

Delta Psystemic = P1 - P2, aortic presssure (mean arterial pressure) - Right atrial pressure

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177
Q

How do you calculate Pulmonary driving pressure?

A

Delta Ppulmonary= P1- P2, Mean pulmonary artery pressure - L atrial pressure

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178
Q

Why is systemic driving pressure so much higher than pulmonary driving pressure?

A

Because Systemic circulation is arranged in parallel resistance

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179
Q

What is P1 of the systemic circulation? What is the pressure?

A

P1 is the beginning of the aorta. Pressure is 120/80

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180
Q

What is P2 of the pulmonary circuit driving pressure? What is the numeric pressure

A

Left atrium
5 mmHg

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181
Q

What is P1 of the driving pressure in pulmonary circuit? What is the pressure?

A

Right ventricle
25/8 mmHg

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182
Q

What is the P2 of driving pressure in pulmonary circulation? What is the pressure?

A

P2 is R atrium
5 mmHg

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183
Q

What is the P2 of driving pressure of the systemic circulation? What is the pressure?

A

R atrium
2 mmHg

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184
Q

What is calculated using the Nernst Equation

A

The point where the diffusional gradient exactly balances the electrical gradient

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185
Q

Define Equilibrium Potential for a given ion

A

The membrane electrical potential at which inward flow of that ion is equal to its outward flow

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186
Q

Equlibrium potential (Eeq) =

A

ion concentration inside/ion concentration outside

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187
Q

Describe the electrochemical basis of membrane potentials

A

Ions flow down their concentration gradient but their electrical potential often directionally opposite

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188
Q

Describe the ionic gradient for Na+ in cardiac cells. Describe the movement of Sodium based on ionic gradient

A

Extracellular Na: 150 mM
Intracellular Na: 15 mM
Outside to In

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189
Q

Describe the ionic gradient for potassium in cardiac cells
And what direction does the gradient move based on ionic gradient

A

Extracellular K: 5 mM
Intracellular K: 10 mM
Potassium In to Out

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190
Q

Describe ionic gradients for Calcium in cardiac cells. Describe the direction of calcium movement based on ionic gradient

A

Extracellular Ca: 2 mM
Intracellular Ca: 0.0001 mM
Outside to In

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191
Q

What type of channels allow more than one type of ion through?

A

Mixed conductance channels

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192
Q

What happens in cardiac ion channels a negative voltages (>70 mV)?

A

M gates open

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193
Q

In cardiac cells, Na+ enters a cell down its concentration gradient-this generates an inward membrane current. What does this cause?

A

Depolarization

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194
Q

What direction to K+ currents move in cardiac cells? What does this do?

A

Outward movement to make the cell more negative inside
(Repolarization)

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195
Q

List the 4 different K+ cannel types in cardiac muscle which allow K+ current to flow at vairious times

A

1.) Inward rectifier
2.) Transient outward K+ current (Ito)
3.) Delayed rectifier K+ currents IKr
4.) Delayed rectifier K+ currents and Iks

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196
Q

Describe what a inward rectifier potassium cardiac channel (Kir) does

A

▪️ Acts as background potassium channel
▪️ Opens at negative voltage and sets the stable negative resting membrane potential that is esp. seen in atrial and ventricular muscle
▪️ -90 mV
▪️ When membrane potential becomes more positive these channels close

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197
Q

Describe what transient outward K+ channels (Ito) do

A

Opens rapidly on depolarization and closes equally rapidly generating transient repolarizing force in ventricals and atrial muscle

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198
Q

Describe what the two types of delayed rectifier channels do?
Irk and Iks

A

Closed at negative voltages
Open when membrane potential becomes more positive, effectively repolarizing cells
Note IKr has a faster activation rate compared to Iks

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199
Q

Cardiac potassium channels in the heart all generally move K+ _________________ the cell. Why are there separate types of channels?

A

All move K++ outside of the cell
Have different parameters for opening and closing, work at different times to move potassium

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200
Q

What type of channel are predominant in cardiac tissue?

A

L type Ca+ channel

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201
Q

What are the two types of cardiac Calcium channels?

A

L type and T type

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202
Q

Where are T type calcium channels found?

A

Atrial and pacemaker cells

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203
Q

What is another name for T type calcium channels

A

Tiny conductance & Transient openings

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204
Q

Describe T type calcium channels

A

Open at -55 mV and close fairly rapidly which is why they are called transient

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205
Q

T/F: T type calcium channels are found in Atria and pacemaker cells and L type calcium channels are found in ventricles and SA node

A

False, L type calcium channels are found thoroughout the heart

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206
Q

What is another name for L type calcium channels

A

Large conductance and Long lasting opening channels

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207
Q

Describe L type calcium channels

A

Open at -40 mV and inactivate more slowly compared to T type and depolarizes the membrane becuase of the inward movement of + charge

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208
Q

Describe Mixed conductance channels in cardiac tissue

A

Permeable to Na+ and K+
Activated slowly by Hyperpolarization at -60 mV
Driving force for Na influx > K efflux
Net inward Na+ movement

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209
Q

Where are funny current mixed conductance channels found?

A

On nodal and purkinje cells

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210
Q

What is the importance behind delayed conduction of the atrial excitation and ventricular by AV node

A

Allows atria to contract before ventricles are excited so atria can fully fill with blood

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211
Q

List the intrinsic pacemaker firing rates in order from slowest to fastest in heart

A

Purkinje system: 20-40 bpm
AV node: 40-60 bpm
SA node: 60-100 bpm

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212
Q

Where does the fastest rate of depolarization occur in cardiac musle?

A

In the SA node

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213
Q

What type of channels are found in Purkinje fibers that allows for slower depolarization?

A

Funny current channels (mixed conductance channels)

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214
Q

If the SA node fails, the AV node can still depolarize, and if both fail the Purkinje system can still function. What property allows firing of action potentials for SA node, AV node and Purkinje system?

A

Intrinsic function

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215
Q

There exists large ______________ directed electro-chemical gradient for Na ions and so when channels open:

A

Inward
brings positive charge into the cell to make less negative

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216
Q

What purpose do Potassium channels serve in cardiac cells?

A

Repolarization, to make inside of cell more negative since potassium is leaving

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217
Q

When the SA node is initiating the action potential, what happens to other tissue? What is this termed?

A

All other tissue activity is suppressed by the SA nodal pacing
Termed: overdrive supression

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218
Q

What are the two types of action potentials found in the heart?

A

Fast and slow response

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219
Q

The SA and AV node produce ____________ response action potential

A

slow

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220
Q

The cardiac atrial and ventricle myocytes produce the ________________ response action potential

A

Fast

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221
Q

What is happening in phase 0 of fast response action potiental

A

Depolarization
-90 mV towards 0 mV
Opening voltage dependent fast Na+ channels
End of this phase marked by drop peak of depolarization and followed by quick slight drop in mV

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222
Q

What is happening in phase 1 of action potential in fast response

A

Early repolarization
Opening of voltage dependent K+ channels, Na+ channels inactivate
Starting to become more negative

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223
Q

What is happening in phase 2 of fast response action potential

A

Plateau phase
- Opening of voltage dependent slow L-type Ca channels to balance with slow delayed rectifier K+ cells
- influx of Ca+, efflux of K+

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224
Q

What is happening in phase 3 of fast response action potential

A

Rapid repolarization
- Closure of L type Ca channels (slow)
- K+ channels open open

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225
Q

What is happening in phase 4 of fast response action potential

A

Resting membrane potential
Inward rectifier K+ channels open (efflux) to maintain resting membrane potential

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226
Q

What two ion channels depolarize cardiac cells?

A

Na and Ca

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227
Q

Why do Na channels act first in an action potential of fast response cardiac cells?

A

Because they open rapidly compared to L type calcium channels which are more slow to open

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228
Q

At the start of phase 4 of fast response action potential in ventricle and atrial mucle, the mV is ~-60 and will continue to drop during this phase. What type of channel opens at -60 mV to ensure continued depolarization?

A

Delayed rectifier K+ currents and IKr and IKs

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229
Q

How many phases are there in fast action potential of ventricle and atrial tissue?
How many phases are there in slow response action potential of pacemaker cells?

A

Fast action potential: 5 phases
Slow action potential: 3 phases

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230
Q

What is happening during phase 0 of slow response pacemaker action potential?

A

Depolarization
Opening of slow L type Ca channels & thus influx Ca

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231
Q

What is happening in phase 3 of slow response pacemaker action potential

A

Repolarization
Opening of delayed rectifier K+ channels, efflux of K
Closure of Ca+ channels

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232
Q

What is happening in phase 4 of slow response pacemaker action potential

A

Pacemaker potential (slow depolarization potential)
- closure K+ channels
- opening funny channels (influx depolarizing charges and net influx Na)
- Opening of two Ca channels, transient and L

233
Q

Compare the difference in Na action in fast and slow response action potential of cardiac cells

A

In fast response, Na plays a large role in quick depolarization
In slow response, the mixed conductance channels allow some

234
Q

Compare the starting voltage of slow response action potential compared to fast response action potential

A

Fast response starts much more negative, -90
Slow response starts about -60

235
Q

In slow response action potential, during slow depolarization, what ion responsible for this? What channels are involved?

A

Calcium is depolarizing the cell first
The T type channels act first to raise calcium levels but L type calcium channels increase Ca levels to a greater extent and push the depolarization past 0 mV

236
Q

The membrane potential in ___________ __________ cells is never stable but changes continuously. Phase 4 depolarizing pacemaker potential enabling ___________ ______ to produce:

A

SA node
SA node
produces the rhythmic action potential without any neurological stimulus

237
Q

When the cardiac cells are at REST: how would you describe the charges on surface and internal of each cell

A

Surface of cells is +
Interior of membrane is negative

238
Q

As an action potential passes each cardiac cell, describe what happens to the charge on the surface of the cell

A

Surface of cell changes from negative to positive

239
Q

The ECG:

A

Reflects changes in the charge on the surface of the heart

240
Q

How is the ECG able to detect changes in surface of cardiac cells?

A

The body fluids conduct the charge to the surface of the skin

241
Q

Where does the first change from + to - on cardiac cell surface occur? Why?

A

On the SA node because it is the first to depolarize

242
Q

T/F: When the SA node is depolarized and cell surface becomes negative, other cardiac cells are following suit at the same time

A

False, the rest of the cardiac cells are still at rest with - cell interior and + cell surface

243
Q

What is created when the SA node depolarizes and the cell surface becomes negative while the remaining cardiac cells are still at rest and + cell surface

A

A dipole is created

244
Q

What creates the upward deflection on ECG?

A

A wave of depolarization moving towards a positive electrode

245
Q

What produces a downward deflection on ECG?

A

A wave of depolarization moving away from positive electrode

246
Q

How many standard limb leads are there?

A

3

247
Q

What do the standard limb leads measure?

A

Lead connects 2 poles, so they measure the electrical activity between the 2 connected poles on the frontal plane

248
Q

Standard limb lead I has a + electrode on:
and - electrode on:

A

L arm +

249
Q

Standard limb lead II has a + electrode on the
and - electrode on:

A

L foot +
R arm -

250
Q

Standard limb lead III has a + electrode on:
- electrode on:

A

Left foot +
Left arm -

251
Q

What do augmented limb leads record? What makes them different?

A

Electrical activity on frontal plane through the heart
These leads create smaller waveforms that the machine must augment and make larger

252
Q

What is different about the augmented limb leads compared to standard limb leads?

A

Augmented (aVR, aVL, aVF) only require unipolar and thus only require 1 electrode to make he lead

253
Q

Where is aVF lead?

A

Left foot

254
Q

Where is aVL lead?

A

L arm

255
Q

Where is aVR lead located?

A

R arm

256
Q

T/F: All precordial leads are positive and bipolar and measure on the frontal plane

A

False, they are all positive but they are unipolar and measure on a transverse plane

257
Q

What is the rhythm strip on an ECG? What is the purpose

A

An expansion of V1, V5, V6 to
Purpose to help identify infrequent abnormalities

258
Q

What is a segment on the ECG

A

A segment of isoelectric neutrality, flat, no electrical activity

259
Q

Where are intervals on an ECG?

A

Areas where at least 1 wave of activity is present

260
Q

What is happening during the P wave

A

Depolarization through the atria
The first + upward deflection on EKG
Initiates contraction of atria

261
Q

The period of electrical neutrality after P wave is called:
What is happening here

A

PR segment
Time required for conduction of action potential though the AV node, Bundle of His and purkinje system to ventricular muscle
Depolarization is occurring

262
Q

What is the PR interval? What does it consist of?

A

Time required for wave of depolarization to move from SA node, AV node, bundle of His and purkinje system
Called atrioventricular conduction time
Consists of P wave an PR segment
0.12-0.2 seconds

263
Q

What interval on EKG might change during increased heart rate? Or lengthens when heart rate decreases?

A

PR interval

264
Q

What might be occurring when the PR interval is >0.2 seconds?

A

Conduction block in AV node

265
Q

What is the QRS interval?

A

Reflects the time of depolarization through the ventricular cardiomyocytes
Time for ventricular contraction
Duration <0.1 seconds

266
Q

During the QRS interval, the ventricles and what else are depolarizing? Why is the focus still on ventricular contraction?

A

Atria repolarizing but electrical conducting is smaller

267
Q

What is happening during the ST segment?

A

Ventricles completely depolarized
Electric neutrality

268
Q

What can it mean when ventricles are elevated or depressed?

A

ischemic event in the ventricles

269
Q

What is occuring during the T wave?

A

Represents Ventricular REpolarization

270
Q

Why does the T wave show up as a positive inflection even though this is repolarization?

A

1.) Repolarization occurs in opposite direction of depolarization in epicardial surface
2.) The direction of ion movement is opposite of depolarization and surface charge of the cells is going from Neg to Pos to produce a positive inflection

271
Q

What is the QT interval? What does this interval envompass?

A

QRS complex, ST segment, T wave
Time required for entire ventricle to undergo one cycle of depolarization and repolarization
An entire ventricular systole (contraction)

272
Q

What interval is corresponding to the heart rate?

A

QT interval

273
Q

What is the normal ratio of QT interval compared to R-R interval?

A

QT interval is normally less than half the R-R interval

274
Q

What does the TP segment represent?

A

Electrical neutrality, atrial and ventricular diastole, filling with blood

275
Q

What does the R-R interval represent?

A

Duration of one complete cardiac cycle/heart beat

276
Q

What does the vertical axis represent on ECG tracing paper?

A

Voltage

277
Q

What do the smallest boxes on the vertical axis of an ECG trace represent? What about the larger boxes of 5 x 5 grid?

A

0.1 mV
0.5 mV

278
Q

What does the horizontal axis on ECG tracing paper represent? What time interval are the SMALLEST boxes? What about the 5 x 5 grid boxes?

A

Time
Smallest: 0.04 sec
5 x 5: 0.2 seconds

279
Q

What is the most common way to calculate heart rate on ECG?

A

Count small boxes between R -R waves

280
Q

How can you calculate an estimate of heart rate from ECG?

A

Using large 5 x 5 boxes, measuring how many large boxes between R wave peaks
Or smallest squares are 60 bpm

281
Q

What is the estimated BPM on EGC if 1 large square between 2 R wave peaks?

A

300 bpm

282
Q

What is the estimated BPM on EGC if 2 large square between 2 R wave peaks?

A

150 bpm

283
Q

What is the estimated BPM on EGC if 3 large square between 2 R wave peaks?

A

100

284
Q

What is the estimated BPM on EGC if 4 large square between 2 R wave peaks?

A

75 bpm

285
Q

What is the estimated BPM on EGC if 5 large square between 2 R wave peaks?

A

60 bpm

286
Q

What is the estimated BPM on EGC if 6 large square between 2 R wave peaks?

A

50 bpm

287
Q

What is the estimated BPM on EGC if 7 large square between 2 R wave peaks?

A

43

288
Q

What is the normal PR interval?

A

0.12-0.2 sec

289
Q

What is the normal QRS complex interval?

A

Less than 0.1 second

290
Q

What is the normal QT interval?

A

Less than half the R-R interval

291
Q

How are the EKG and cardiac cycle related?

A

ECG shows electrical events of the heart
Cardiac cycle shows mechanical events of the heart
Electrical events always precede mechanical events of the heart

292
Q

The P-wave occurs just before:

A

Atrial contraction b/c electrical activity PRECEEDS mechanical activity

293
Q

The __________ ______________________ begins just prior to ventricular contraction/systole because electrical activity PRECEEDS mechanical activity

A

QRS Complex

294
Q

The T wave (ventricular repolarization) occurs just before:

A

Ventricular relaxation/diastole

295
Q
A
296
Q

What are the 2 requirements of a normal ECG?

A

1.) Each P wave followed by QRS complex
2.) HR 60-100 BPM

297
Q

What are the 3 types of AV block?

A

1.) First degree heart block
2.) Second degree heart block
3.) Third degree heart block

298
Q

What is the basis of AV block?

A

Preventing or delay impulse at SA Node from entering ventricles

299
Q

Which type of AV heart block has 2 subtypes?

A

Second degree AV block

300
Q

Where can an AV block occur??

A

AV node, bundle of His, bundle branches or Purkinje system

301
Q

What is occurring in first degree heart block?

A

Partial degree block of AV node and conduction to ventricles is partially blocked
- slow conduction through AV node down to bundle of his and ventricles

302
Q

What is happening in Mobitz Type I block? What degree of AV block is it?

A
  • Partial heart block of AV node also called Wenchebach block
  • The impulse is not transmitted through the AV node
  • Second degree heart block
303
Q

What is happening in Mobitz Type II block? What degree of AV block is it?

A
  • Partial block of the Bundle of His
  • Second degree heart block
304
Q

What are the 2 criteria for determining first degree incomplete heart block?

A

1.) PR interval should be more than 0.2 seconds
2.) Sinus rhythm exists (P-QRS-T for every beat)

305
Q

Why is third degree heart block sometimes called complete heart block?

A

The impulse from SA node or Bundle of His is completely blocked.
Impulse does not reach bundle branches or any lowered down

306
Q

If the only abnormality shown on ECG is a prolonged PR interval, what condition is indicated?

A

First degree AV heart block

307
Q

In second degree heart block:

A

Not all atrial impulses are transmitted through the AV node

308
Q

In second degree heart block Mobitz Type I , the ____ wave is not followed by __________ complex because:

A
  • As PR interval progressively increases, the conduction through the AV node may fail resulting in a lost QRS complex after P wave
  • Intermittent conduction failure and loss of ventricular contraction
  • After the dropped QRS complex, the next impulse is P wave followed by QRS complex
309
Q

Where is the failure of conduction in Mobitz Type I heart block? Where is the failure of conduction in Mobitz Type II heart block?

A

Mobitz I: AV node
Mobitz II: Bundle of His

310
Q

Both first degree AV block and second degree Mobitz Type I (Wenkebach) block involve the AV node, what delineates each other?

A

In First degree, there is still conduction of ventricles, just delayed at the AV node
In Mobitz Type I, the impulse does not reach the ventricles

311
Q

In second degree heart block, Mobitz Type II there is:
Mobitz Type II block can lead to:

A

Sudden unexpected loss of AV conduction and loss of ventricular activation that occurred beyond the AV node
Cardiac arrest and/or insertion of pacemaker

312
Q

What is the difference in tracing between Second Degree heart block Mobitz Type I & II?

A

In type I there is progressive lengthening between P wave and QRS
In type 2 there is no wave lengthening on ECG tracing, sudden and not predicable except for ratio between conducted beat and blocked beat

313
Q

T/F: In third degree heart block, there are no impulses transmitted through SA node

A

False, there are no impulses transmitted through or beyond the AV node so only the atria contract
The ventricles contract separately and lower via intrinsic impulse

314
Q

Describe ECG tracing of Third degree heart block

A

1.) Regular interval, small P waves, 100 bpm
2.) Separately, longer interval QRS complexes, ~ 35 bpm
3.) For every QRS complex generated by ventricle, there are 4 P waves

315
Q

Where in the heart conduction system do sinus bradycardia and tachycardia arise?

A

In the SA node

316
Q

The ST and TP segments are on the “isoelectric line” in a healthy heart because:

A

The whole ventricular surface is the same charge

317
Q

ST segment shift (elevation or depression) most often indicates:

A

a myocardial ischemia or infarction

318
Q

What is the requirement for regular heart rhythm

A

R to R intervals are the same for each heart beat and the rhythm is maintained

319
Q

A regularly irregular heart rhythm represents a pattern of beats that repeats. Give an example of a regularly irregular rhythm

A

Second degree Mobitz Type II block since there is a predicable lost QRS complex

320
Q

In an irregularly irregular heart rhythm:

A

There is no underlying regularity, the R to R interval is completely irregularly

321
Q

During _____________________ the depolarization down the atria or ventricle is so slow that by the time the action potential exits the tissue:

A

fibrillation
a new action potential is already exciting the tissue again.

322
Q

The absence of P waves and irregular R to R intervals with presence of QRS complex on ECG tracing, this indicates

A

A fib

323
Q

Described as an “undulating baseline,” there are no QRS complexes or P waves, and total absence of any pattern on ECG tracing indicates:

A

V fib

324
Q

In an irregularly irregular heart rhythm:

A

There is no underlying regularity, the R to R interval is completely irregularly

325
Q

What is the mean electrical axis of the heart?

A

Tells us direction of electrical condition during during VENTRICULAR depolarization
- usually away from R towards Left

326
Q

What are 3 discernable indications made from the mean electrical axis?

A
  • Orientation of heart
  • Size of ventricular chambers
  • Conduction block
327
Q

____________________ _____________________ is an equilateral triangle around the heart formed by the three standard limb leads. F

A

Einthoven’s triangle

328
Q

What is the largest interval found on ECG? What does it comprise?

A

QT Interval
Includes: QRS complex, ST segment, T wave

329
Q

What is a normal MEA? What is the exception to this?

A

Between 0° and +90°
Some cardiologists extend to -30°

330
Q

Between what leads is a normal MEA (mean electrical axis)

A

Between 0 Standard Limb lead I and + pole augmented lead aVF

331
Q

Where is R axis deviation found on MEA?
Between what leads?

A

Between +90° and +150°
- pole standard limb lead 1 and + pole augmented limb lead aVL

332
Q

What is indicated if MEA is on R axis deviation?

A

Normal finding in children, tall thin adults, some athletes
R ventricular hypertrophy

333
Q

Where is Left axis deviation found on MEA? Between what leads?

A

Between 0° and -90°
0 pole standard limb lead I and - pole augmented lead aVF

334
Q

What might be indicated by Left axis deviation on MEA?

A

Commonly seen in conditions causing Left ventricular hypertrophy
Inferior MI
R branch bundle block

335
Q

List the 3 ways to calculate MEA
What are they focusing on?

A

Semi Quantitative method
Net zero load method
Quick Approximation
Focus on net direction of aVF and limb lead I

336
Q

How does Semi Quantitative Method determine MEA?

A

Uses net direction of QRS complexes of the six limb leads (use radial axes)

337
Q

How does Net Zero load method work?

A

From the net direction of QRS complex of the six limb leads (uses radial axes)
Location where Q wave and S cancel each other out
Use the lead that forms a right angle with the lead that contains the net zero QRS

338
Q

The “Quick and Dirty” method of MEA determination uses which two leads?

A

Lead I and aVF (L foot)

339
Q

What determines normal MEA if using the Quick & Dirty method?

A

Lead I: + Deflection, go to Positive pole
aVF: + Deflection, go to + Pole

340
Q

What determines R axis deviation of MEA if using Quick and Dirty method?

A

Lead I: - deflection, so go to Negative pole
aVF lead: + deflection, go to + pole

341
Q

T/F: Each axis for determining the Mean Electrical Axis has a negative and positive pole

A

True

341
Q

What determines Left axis deviation of MEA if using Quick and Dirty method

A

Lead I: + deflection, go to + quadrant
aVF lead: - Deflection, go to - quadrant

342
Q

What phases of the cardiac cycle comprise diastole?

A

Phase 1-3

343
Q

When using Wiggers diagram, which part of the heart is being represented?

A

L side of heart

344
Q

What is the scale of aortic blood flow in the aorta?

A

0-5 L/min

345
Q

List phases 1-3 during diastole

A

1.) Rapid ventricular filing
2.) Reduced ventricular filling
3,) Atrial systole

346
Q

What is occurring during diastole

A

Heart is relaxed, filling with blood

347
Q

What is the longest phase during diastole?

A

Phase 2, reduced ventricular filling

348
Q

What starts phase I of diastole?

A

When L atrial pressure becomes greater than L ventricular pressure, this forces the mitral valve to open and allow blood flow into L Ventricle

349
Q

Why do both L ventricle and atrial pressure gradually fall during phase 1?

A

In atria: blood is leaving, so pressure down
In ventricle: when blood is entering ventricle the relaxed state of ventricle to stretch offsets the raised pressure of blood intake

350
Q

T/F: The pressure of the aorta during phase I of diastole is higher than L ventricle pressure which keeps the aortic valve closed

A

True

351
Q

What is the volume at start and end of phase 1, rapid ventricular filling, of ventricle?

A

Ventricle start at 50-60 mL and passively fills to ~110 mL

352
Q

Why is rapid ventricular filling in diastole considered PASSIVE filling?

A

Because the atria is not contracting to expel blood, the pressure gradient is allow blood to flow from High to Low pressure w/o energy input

353
Q

Why does pressure drop in aorta during phase I of diastole?

A

Because there is no blood flowing into aorta and aorta is emptying while blood flows to peripheral arteries

354
Q

What does the ECG tracing look like during phase I of diastole?

A

Isoelectric because the heart is relaxed, Between end of T wave and start of P wave

355
Q

Why is ~20 mL of blood flowing from L atria to L ventricle during phase 2 of diastole (reduced ventricular filling)B

A

Ventricle is reaching its max capacity

356
Q

During phase II of diastole, the L ventricular pressure creeps up as max volume capacity is reach. Why does L atrial pressure slightly increase?

A

Blood is starting to refill with blood

357
Q

What is happening to the aortic pressure and volume during phase II of diastole?

A

Pressure continues to drop b/c blood still flowing through peripheral arteries
Volume cont. 0

358
Q

What heart sounds may be heard during Phase 2 of diastole?

A

None

359
Q

What marks the end of phase 2, start of phase 3 of diastole in cardiac cycle

A

Beginning of P wave to signal atrial depolarization

360
Q

What is the name of phase I of diastole?

A

Rapid ventricular filling

361
Q

What is the name of phase II of diastole?

A

Reduced ventricular filling

362
Q

What is the name of Phase III of diastole?

A

Atrial systole

363
Q

Why do BOTH atrial and ventricular pressure increase during phase 3 of diastole?

A

Because the atria are contracting, they expel more blood in to ventricle increasing vol and pressure of already filled ventricle

364
Q

Turbulence (sound 4) is created during atrial systole (phase 3 of diastole). Why?
Is it normal

A

Created by blood pushing against ventricle
Not often heard

365
Q

T/F: There is blood flow from the L ventricle to aorta during phase 3 of diastole

A

False

366
Q

What creates the slight increase in venous pressure during phase 3, atrial systole during diastole?

A

There is light backflow of blood from atria back in to veins

367
Q

T/F: The mitral valve closes after phase 2 of diastole when atria begin to contract

A

FALSE, the mitral valve closes only AFTER phase 3

368
Q

Aortic pressure steadily _____________________ during diastole. BUT overall, the total pressure is ___________________ than pressure in both atria and ventricle

A

Decreases
greater

369
Q
A
370
Q

List the 4 phases of systole

A

4.) Isovolumic contraction
5.) Rapid Ejection
6.) Reduced ejection
7.) Isovolumic relaxation

371
Q

What is the name of phase 4 of systole

A

Isovolumic contraction

372
Q

What occurs right before phase 4 of systole?

A

QRS complex to allow for ventricular depolarization

373
Q

What is the first step of phase 4 of systole?

A

Ventricles starting to contract which increases pressure such that it is greater than atrial pressure and forces mitral valves closed

374
Q

What sound is heard during phase 4 of systole?

A

Lub sound created by turbulence of mitral valve closing
Sound 1 heard in healthy adults

375
Q

T/F: During isovolumic contraction during systole, the ventricular pressure is so high the aortic valve is forced open

A

False, the aortic valve is still closed

376
Q

Why is phase 4 termed isovolumic contraction?

A

The ventricles are closed chambers, both mitral valve and aortic valve are closed while the ventricle is contracting.
So pressure is increases but volume has no where to escape to

377
Q

Why does venous pressure increasing during phase 4 of systole?

A

Because atrial are continuing to receive blood and pressure is transmitted to veins with some backflow

378
Q

What marks the start of phase 5: rapid ejection phase in systole

A

Aortic valve opens when the ventricular pressure exceeds aorta pressure

379
Q

T/F: only closure of valves produces sounds in normal healthy adults

A

True

380
Q

T/F: Because the aorta is such a large vessel, the opening of it during rapid ejection phase creates the “dub” sound in heart

A

False, only the closing of valves produces sounds in healthy heart

381
Q

Why do BOTH ventricular pressure and aortic pressure increase during rapid ejection (phase 5) of systole?

A

Because the ventricle is continuing to contract so pressure remains high
Aorta now filling with blood

382
Q

The peak pressure measured at phase 5 of systole is termed

A

Systolic pressure

383
Q

In what phase do we see stroke volume? What is stroke volume?

A

Stroke volume is the amount of blood expelled by L ventricle into aorta
- Seen in phase 5

384
Q

Why does venous pressure drop during rapid ejection phase of systole?

A

The sudden increase in aorta volume and flow of blood out of ventricle pulls the mitral valve into the ventricle which increases the space in mitral valve which decreases pressure in atria and subsequently the veins

385
Q

What does the ECG tracing show during phase 5 of systole?

A

Shows ST segment, electrically neutral due to ventricles being completely depolarized

386
Q

What is the name of phase 5 of systole?

A

Rapid ejection phase

387
Q

What is the name of phase 6 of systole?

A

Reduced ejection phase

388
Q

In phase 6 of systole:
___________ volume still decreases but at a slower rate
________________ blood flow decreases
______________ and ____________________ pressure begins to decline as less volume is ejected

A

Ventricular
Aortic
Aortic & ventricular

389
Q

Why does ventricular pressure begin to drop in phase 6 of systole?
Why does aortic pressure begin to drop in phase 6 of systole?

A

The ventricle contraction begins to taper off so pressure drops
The blood in the aorta begins to move out to periphery

390
Q

What is happening to atrial pressure during reduced ejection phase of systole?

A

The atria is still closed to ventricle and continuing to fill with blood so the pressure rises and thus venous pressure is also rising

391
Q

What tracing is seen on ECG during phase 5 of systole?

A

The T wave as the ventricles begin to repolarize

392
Q

What marks the end of phase 6, beginning of phase 7 of systole?

A

Closure of the aorta

393
Q

Why does the aortic valve close?

A

As the ventricle stops contracting, the pressure begins to drop enough where the aortic pressure is greater than ventricular pressure forcing the aortic valve closed

394
Q

In phase 7 of systole, the drop in pressure of the ventricle and subsequent closure of the aortic valve does what?

A

The pressure decrease makes the blood want to flow back into the ventricle, but the aortic valve is closed which creates the “Dub” sound, sound 2

395
Q

What does the ECG tracing look like during phase 7, isovolumic relaxation of systole

A

Isoelectric because all of the cells have repolarized

396
Q

The pressure decrease makes the blood want to flow back into the ventricle, but the aortic valve is closed which creates the “Dub” sound, sound 2. This can also be seen in the pressure of the aorta known as:

A

Dicrotic notch

397
Q

In phase 7 of systole, both the aortic valve and mitral valve are closed so no volume change in ventricle. But the ventricle never expels all blood volume, the remaining volume is termed:

A

End systolic volume

398
Q

End Diastolic volume represents the amount of blood in the ventricle when:
End Systolic volume represents the amount of blood in the ventricle when:
Stoke volume is:

A

Full
After emptying but some blood still remains
Difference between these two, about 70 mL as it is the amount of blood pumped out of ventricle

399
Q

Why does atrial pressure rise during phase 7 of systole? Why does venous pressure rise during phase 7 of systole?

A

The mitral valve is still closed and blood still being received so both venous and atrial pressure up

400
Q

What is cardiac output?

A

Heart rate * Stroke volume
Amount of blood pumped per minute

401
Q

What is normal cardiac output at rest?

A

5 L/min

402
Q

What is normal stroke volume

A

70 mL

403
Q

The main neurotransmitter in sympathetic division is:

A

Norepinephrine which can allow for secretion of epinephrine from the adrenal medulla

404
Q

The sympathetic nervous system is initiated when there is increase in:
Works where in the heart:
Increases: ________________ and ________________ via action of:

A

Activity
Atria and ventricles
Heart rate and contractility
Catecholamines

405
Q

What are catecholamines?
Give 3 examples

A

Monoamines that act as hormones and or neurotransmitters
1.) Epinephrine
2.) Norepinephrine
3.) Dopamine

406
Q

The main neurotransmitter in parasympathetic system is:
This controls:
Works where in the heart:
Decreases: ___________ & _______________

A

Acetylcholine
Controls resting heart rate
Works mostly Atria via SA & AV node
Heart rate and contractility

407
Q

What adrenergic receptors work with norepinephrine?

A

β adrenergic receptors

408
Q

To increase heart rate via ANS activity:
1.) SNS secretes norepinephrine which acts on β adrenergic receptors
2.) Na+:
3.) Ca+:
4.)

A

2.) Increase Na+ permeability by accelerating activation of funny current channels in slow type channels (SA/AV node) which increases rate of depolarization
3.) Increased Ca+ permeability
4.) Increases rate and conduction velocity to allow action potential to excite next cells, reactivates faster

409
Q

To control heart rate via PNS:
1.) PNS secretes acetylcholine to Muscarinic receptors
2.) K+:
3.) Na+:
4.) Ca+:

A

2.) Increase permeability of K+ which increases hyperpolarization to make depolarization harder
3.) Decrease permeability of Na+ to reduce rate of polarization
4.) Decrease Ca+ permeability which delays time it take to reach mV 0 where an action potential could take place

410
Q

Heart rate is majorly controlled by:

A

SA node and AV node transduction

411
Q

What are the 2 main pathways to control cardiac output?

A

Intrinsic and extrinsic control

412
Q

What 3 things control stroke volume (vol of blood expelled from ventricle to aorta) ?

A

Afterload
Preload
Contractility

413
Q

In Intrinsic control, what increases stroke volume?

A

Increasing end diastolic volume

414
Q

In intrinsic control, what decreases stroke volume?

A

Afterload

415
Q

What is preload?

A

Degree of myocardium stretch before contraction
AKA end diastolic volume

416
Q

What is afterload?

A

Resistance against systolic contraction
The pressure generated during ventricle contraction prior to opening aortic valve
The pressure that must be overcome to open the aortic valve

417
Q

List 3 other terms for afterload:

A

1.) Aortic pressure
2.) Arterial pressure
3.) Total peripheral resistance

418
Q

Define contractility

A

Strength of contraction at any given End diastolic volume

419
Q

What does increasing preload do?

A

Increases stroke volume buy increasing the volume of blood in the L ventricle

420
Q

What does increasing afterload mean?

A

Decreases stroke volume: Increasing pressure pushing down on ventricle so the time required for ventricle pressure to supersede aortic pressure to force aortic valve open and expel blood. This means there is less time for the actual contraction and expelling blood because using more time to build up pressure to open aorta

421
Q

Increasing ___________ _____________&raquo_space; increases preload&raquo_space; increases ___________ ________________&raquo_space; increases ______________ _______________

A

Venous return
stroke volume
cardiac output

422
Q

As venous pressure rises, cardiac output drops, why?

A

Because there is more pressure that venous return must push against the the volume returning to heart is less which reduces amount of blood that can be returned to heart and subsequently expelled

423
Q

Define: Frank-starling law

A

Energy of contraction is proportional to the initial length of the cardiac muscle fiber

424
Q

Since cardiac myofibers cannot recruit more cells to increase tension, what law and concept is used to increase contraction

A

By increasing filling of heart, the stretch and tension of myofilaments is increased to reach optimal sarcomere overlap which allows for stronger recoil

425
Q

What mechanism works in exerting extrinsic control on stroke volume

A

Sympathetic nervous activity

426
Q

Increasing _____________________ via activation of sympathetic nervous system will increase ______________________ via extrinsic control to overall, increase ________________ ________________

A

contractility
stroke volume
cardiac output

427
Q

Define: contractility

A

Strength of contraction at any given end diastolic volume

428
Q

Positive ionotropic effect is equivalent to:
It is enabled by catecholamines or digoxin

A

increasing contractility and thus inc. stroke vol, subsequently inc. cardiac output

429
Q

Negative ionotropic effect is equivalent to:
It is enabled by β blockers or heart failure

A

Decreasing contractility, thus decreasing stroke volume and subsequently decreasing cardiac output

430
Q

β blockers will decrease ionotropic and chronotropic activity of heart, meaning:

A

Decreased contractility
Decreased HR
Decreased Cardiac output overall

431
Q

How does the sympathetic nervous system increase contractility of the heart?

A

SNS secretes norepinephrine which acts on β₁ receptors which
1.) increases permeability of Ca+, easier to activate L type channels
2.) increases quantity of L type calcium channels in ventricle tissue
3.) Increase Phospholamban activity to increase Ca+ sequestering to increase EDV
Allows for more forceful contraction

432
Q

List the 3 physiologic areas of importance in fetal circulation

A

Ductus arteriosus, foramen ovale, ductus venosus

433
Q

In fetal circulation the L and R heart pump:
Why is this?

A

In Parallel
Because only some blood goes into pulmonary artery unlike in adults

434
Q

In fetus, where is the ductus arteriosus located?

A

Between the pulmonary artery and shunts blood straight to the aorta to systemic circulation

435
Q

In fetus, where does O² come from?

A

Comes from the placenta, the O² diffuses across the placenta and is delivered via the ductus venosus

436
Q

In utero, oxygenated blood comes up through the inferior vena cava via:

A

Ductus venosus that connects to the placenta

437
Q

In fetus, blood from the R atrium shunts directly to the L atrium via:

A

Foramen ovale

438
Q

In fetus, though both sides pump in parallel, which side of the heart pumps more volume? Why is this so?

A

R heart heart
Since not much blood is being pumped into the pulmonary artery, not much vol blood being returned to L side of heart

439
Q

T/F: In fetus, cardiac output is irrelevant and more focus on combined ventricular output due to the L side of heart pumping more volume than the R

A

False, R side pumps more volume than L

440
Q

About how much fetal blood passes through the ductus arteriosus? Where is the ductus arteriosis?

A

~60% of blood volume
Shunts blood coming from R ventricle to pulmonary artery straight to aorta

441
Q

Why is the volume of blood in fetus large?

A

Because the O² concentration in fetal blood is low, so need more volume to have enough O²

442
Q

What is the [ O² ] in aorta of fetus?

A

65%

443
Q

What is the [ O² ] in RV and LV of fetus?

A

RV: 55%
LV: 65%

444
Q

Where does Oxygenated blood come from when considering blood going to brain and coronary circulation in fetal circulation? Why?

A

From the aorta since it has the highest O2 saturation

445
Q

During late stages of gestation, the lungs and gut receive larger % combined ventricular output to engage maturity for birth. Compare or contrast this to fetal regional blood flow of brain, lungs, kidney, gut.

A

While the lung and gut start to get a larger percentage of ventricular output, the kidney remains with the highest regional blood flow. The brain and lungs also have greater absolute flow compared to the gut further in gestation.

446
Q

T/F: Since the L and R heart pump in parallel in fetal circulation, the oxygen circulating in fetal circulatory is even

A

False, the most oxygenated blood is biased towards the brain and coronary circulation

447
Q

Describe the first breath after birth

A

Difficult because the lungs are stiff
Need a very large negative pressure to forcefully expand lungs
▪️ - pressure as low as 60 mmHg and + pressure as high as 40 mmHg to expand the lungs

448
Q

What mechanism aids in second breath after birth to make breather easier?

A

Production of pulmonary surfactant to decrease surface tension in alveoli
Fluid in lungs is reabsorbed so the inflation of lungs is easier

449
Q

About how long after birth is pressure volume loop comparable to adults?

A

~ 40 min, effective change in volume with small changes in +/- pressure

450
Q

During gestation, pulmonary vascular resistance is high so blood flow is low, does this change after birth?

A

Yes, because the ductus arteriosus closes and no longer straight shunt from R ventricle to pulmonary artery to aorta
So the blood may go through low resistance pulmonary circulation and arterial pressure drops while blood flow increases

451
Q

What may happen in the pulmonary vascular resistance does not decrease after birth?

A

Persistent pulmonary hypertension of newborn

452
Q

Approximately where is fetal blood pressure maintained?

A

40-50 mmHg

453
Q

T/F: Since O2 and CO2 diffuse between air in lungs and pulmonary circulation they freely travel through systemic ciruclation

A

False, O2 and CO2 are not very soluble in the blood and must use other transport mechanisms

454
Q

When breathing in, the ____________________ expands and the ___________________ lowers to pull lungs toward pleural space and expand. This makes the pressure in the pleural space more ____________________ which causes lungs to expand.

A

Chest wall
diaphragm
negative

455
Q

What condition of the pleural space helps hold lungs open?

A

The slightly negative pressure in pleural space

456
Q

Each alveolus is surrounded by:

A

Pulmonary capillaries

457
Q

T/F: In addition to pulmonary circulation, the lungs also have bronchial circulation

A

True

458
Q

What is the purpose of the bronchial circulation?

A

To supply blood to areas of lung that do not undergo gas exchange

459
Q

The blood coming from the pulmonary vein is not 100% O2 saturated, why?

A

Because of the bronchial circulation. This circulation system supplies oxygen to the lungs that do not undergo gas exchange so when this blood leaves the lungs it is not fully oxygenated and is returned to pulmonary venous which lowers the O2 saturation
AKA right to left shunt

460
Q

What does high compliance mean?

A

Can have large change in volume for low change in pressure

461
Q

T/F: Since pulmonary arteries and branches are under involuntary control, they are surrounded by smooth muscle

A

False

462
Q

Why is it so important for pulmonary circulation to exhibit high compliance?

A

1.) When cardiac output increases, the volume can greatly increase and low pressure must be maintained during this increase

463
Q

T/F: The diameter and length of pulmonary vessels can be changed easily by mechanical forces like in the rest of the body

A

False, only applicable to pulmonary circulation

464
Q

ΔPressure = ______________________ X _______________________

A

ΔPressure = Flow X resistance

465
Q

Cardiac output must be <,>, = in systemic and pulmonary circulation

A

Must be equal since they are in series with each other

466
Q

______________ and _______________ factors can change pulmonary resistance

A

Passive and active

467
Q

List 3

A
468
Q

What is transmural pressure?

A

Pressure gradient across the wall of a vessel, trachea ‘
P in- P out

469
Q

Where are extra alveolar vessels located?

A

In the pleural space and not surrounded by alveoli
NOT part of bronchial circulation

470
Q

Pulmonary circulation is a _____________ pressure, _________ resistance, and ___________ compliance circulation.

A

low
low
high

471
Q

At large lung volumes (inspiration), the resistance in extra-alveolar is ___________ while the alveolar vessel ___________________. Why?

A

decreases
increases
Since the chest wall is expanding, the pleural space becomes more negative which allows more room for extra alveolar vessel
The alveoli are expanding which lengthens and squishes the alveolar vessels

472
Q

At what point is lowest total resistance in the lungs?
At what point is there highest total resistance in the lungs?

A

Functional residual capacity
Residual volume (where the minimum amount of air is present and the rest is forcefully expelled)

473
Q

During expiration, resistance increases:
resistance decreases:
Why

A

Resistance increases in extra alveolar space b/c the intrapleural pressure is increasing
Resistance decreases in alveolar space b/c pressure decreasing and vessels are shortening

474
Q

How do you calculate total vascular resistance of the lung:

A

Add alveolar and extra alveolar resistance
since they are in series the resistance is additive

475
Q

List the 3 components of passive control of pulmonary vascular resistance

A

1.) Lung volume and the transmural pressure gradient across the vessels
2.) Pulmonary blood flow & blood pressure
3.) Gravity

476
Q

In lungs, as pulmonary arterial pressure increases, resistance ____________________. Why?

A

Decreases
due to high compliance of pulmonary

477
Q

Describe recruitment in terms of passive control of pulmonary vascular resistance

A

In the lungs, all vessels are open but not all have flowing blood because pressure is not high enough to force blood through them
As pressure rises, these vessels begin to fill with blood
Happens in the apex of the lung

478
Q

Following recruitment of vessels in the lung ,there is distention for passive pulmonary resistance control. What is the distension?

A

After the capillaries are all recruited, these vessels can easily stretch to increase amount of blood flowing through them

479
Q

Where in the lung is there the greatest blood flow? Why is it not uniform?

A

In the base
Due to gravity. Since the pulmonary artery is below the apex of the lung, most of blood flows toward the base

480
Q

Where is vascular pressure highest in the lung?

A

At the base again because blood flow is the greatest here

481
Q

When is alveolar pressure = to atm?

A

Between breaths when the trachea is open

482
Q

Explain the pressure difference between arterial pressure, alveolar pressure and venous pressure in Zone 1 (Apex) of the lung. How does this affect pulmonary vessels

A

Alveolar pressure is greatest
Arterial pressure is greater than venous pressure
Pulmonary vessels are squished with no blood flow

483
Q

Explain the pressure difference between arterial pressure, alveolar pressure and venous pressure in Zone 2 of the lung. How does this affect pulmonary vessels

A

Arterial pressure is largest
Alveolar pressure is larger than venous pressure
Some blood flow through vessels but limited due to alveolar pressure being higher than venous pressure, so resistance is high enough to reduce blood flow

484
Q

Explain the pressure difference between arterial pressure, alveolar pressure and venous pressure in Zone 3 (base) of the lung. How does this affect pulmonary vessels

A

Arterial pressure greatest
Alveolar pressure larger than venous pressure
Arterial pressure high enough to push blood flow entirely through the vessel

485
Q

What are 2 conditions where in Zone 1 would exist in the lung. FYI zone 1 does not normally exist under normal circumstances

A

1.) Positive pressure ventilation
2.) During hemorrhage

486
Q

What is the most important factor mediating active control of pulmonary circulation is:

A

Oxygen

487
Q

_____ Partial pressure of oxygen in the alveolar air causes:
This is termed hypoxic pulmonary vasoconstriction

A

Low
vasoconstriction of small pulmonary arteries

488
Q

When would hypoxic pulmonary vasoconstriction exhibit preserving effects?

A

I.e. if something is obstructing part of the lung, the blood flow will be directed AWAY from that area since it cannot participate in gas exchange

489
Q

At high altitude what happens to partial pressure of oxygen? How does this affect physiology?

A

The partial pressure of oxygen is lowered so vasoconstriction occur which increases pulmonary arterial pressure

490
Q

High partial pressure of ______ and low pH in the alveolus can promote vasoconstriction

A

CO2
Importantly, this acts on SMALL level compared to active control based in O2 partial pressure

491
Q

Describe normal pulmonary capillary fluid balance.

A

Since the overall arterial pressure is low, the hydrostatic pressure is low and little fluid is exchanged in pulmonary capillaries. What little amount is pushed out is removed via lymphatic system

492
Q

How might heightened arterial pressure effect pulmonary capillary fluid balance?

A

If the arterial pressure increases the hydrostatic pressure in capillaries then too much fluid may be pushed into interstitial space that the lymphatic system is not able to remove
Pulmonary edema

493
Q

Describe the early stage (interstitial edema)

A

fluid between capillary and alveolus
increases diffusion distance between oxygen and carbon dioxide between alveoli and plasma reducing gas exchange in the lung

494
Q

What is happening in late stage edema?

A

The alveoli are filled with fluid so gas exchange cannot take place

495
Q

The _____________ contributes a large amount of Angiotensin I conversion. Why?

A

Angiotensin I converted to Angiotensin II via ACE
Because the lung receives such a high volume of blood, the entire circulation

496
Q

Hemodynamics: Pressure difference drives _________________. Amount of flow is determine by:

A

Flow
ΔP and resistance

497
Q

What is the equation to calculate Ohm’s law

A

ΔP = Flow * resistance
Flow may also be represented as Q or Q.

498
Q

Hemodynamics: Resistance = k/ radius ^ _____

A

power of four
So if P same, as radius INCREASES, resistance decreases
As radius DECREASES, resistance INCREASES

499
Q

Hemodynamics: How do resistance and length relate to each other.

A

They are proportional where, Resistance = k * Length
If Length increases so does resistance

500
Q

Why is it important for terminal arterioles to be the primary resistance vessels of the body?

A

Because by increasing the resistance at terminal arterioles, and decreasing radius, the flow slows down to allow time for gas and nutrient exchange at the capillary beds

501
Q

What is the equation representing the la of LaPlace?

A

Wall tension (T) = P (hydrostatic pressure) * R (radius)
Wall tension=force pulling vessel apart

502
Q

In the law of LaPlace, the increase in radius increase wall tension, why is this?

A

B/c if the radius is bigger, there is more surface area for the hydrostatic pressure to interact with thus increasing the wall tension

503
Q

If terminal arteriole resistance is high, why is total peripheral resistance not correspondingly high?

A

Because the parallel arrangement of the vasculature reduces the overall resistance

504
Q

The mean arterial pressure is:

A

Average pressure OVER TIME (between systolic and diastolic)

505
Q

How to calculate Mean Arterial pressure:

A

MAP = 1/3 (systolic pressure) + 2/3 (diastolic pressure)

506
Q

T/F: Velocity is the same as blood flow

A

False, flow is a component comprising velocity

507
Q

If wanting to relate flow and velocity of blood, what must be accounted for? How are all 3 components related?

A

Velocity = Flow/total area (cross sectional area)

508
Q

Where does Ca+ bind in skeletal muscle during excitation contraction?

A

Binds to troponin C

509
Q

What happens after Ca+ binds to troponin C?

A

The troponin moves the associated tropomyosin towards the cleft which allows exposure of the myosin binding site of the actin filament

510
Q

In the resting state, what is connected to the myosin heads?

A

ADP and Phosphate

511
Q

When Pi is released from myosin, what happens?

A

The power stroke, the myosin heads rotate down which moves the actin filament on top of itself
After ADP is released

512
Q

What is attached to myosin and thin filament during rigor state?

A

Nothing, the ADP and Pi have been released

513
Q

What is ATP role in cross-bridge cycling

A

ATP promotes the release of myosin heads from thin filaments but still bent
Myosin will convert the ATP to ADP and Pi to return to upright orientation
They hydrolysis of ATP to ADP and P on thick filament sets up for power stroke

514
Q

How is cross bridge cycling ceased?

A

Ca+ is “sequestered” aka pulling Ca back into the sarcolemma via SERCA

515
Q

What is SERCA?

A

Calcium ATPase that pulls Ca from the sarcomere back into the sarcolemma

516
Q

What is the most abundant protein in the sarcoplasmic reticulum of skeletal muscle?

A

SERCA

517
Q

SERA transports ____ molecules of Ca+ for each _______ hydrolyzed

A

2 molecules Ca+ re-sequestered for every ATP hydrolyzed

518
Q

Where is calcium stored in skeletal muscle?

A

Calsequestrin stores the calcium in SR so Ca is ready to flow through RyR

519
Q

How does arterial compliance impact circulation?

A

Arteries are relatively non-compliant.
There is some stretch, so during systole the small stretch build ability for elastic recoil that is engaged during diastole to further expel blood

520
Q

How does blood flowing through vessel walls seemingly decrease viscosity?

A

The RBC flowing through the vessel interact with the wall which optimizes flow

521
Q

What is “shear thinning” and how does it impact blood viscosity?

A

The tendency for erythrocytes to move to center of the tube where higher flow rate occurs
Higher velocity causes shear thinning
Aggregation decreases in this state and such blood viscosity decreased

522
Q

T/F: As vessel diameter decreases, viscosity decreases. If so, why?

A

T
As blood vessels become smaller with the same volume flowing through increases velocity

523
Q

List the 5 components that affect blood visocity

A

Hct
Plasma proteins
Shape of RBC
Velocity of flow
Vessel Diameter

524
Q

What is Renyolds number used for?

A

Used to predict if blood flow will be turbulent of laminar

525
Q

Which type of flow is preferred, turbulent or laminar? Why?

A

Laminar
Organization of flow is in parallel
Blood flow toward the center is fastest while the blood flow on the wall is slowest
Most efficient

526
Q

Why can turbulent flow be heard?

A

Because the turbulent flow is not energy efficient, and energy lost is converted to sound

527
Q

Central venous pressure is synonymous to:

A

Right atrial pressure

528
Q

When cardiac output is normal (5 L/min) the central venous pressure is low, why?

A

The cardiac output is pulling blood out of the veins, lower volume decreases pressure, which allows for more volume to enter the veins

529
Q

How does increasing volume increase central venous pressure and vice versa?

A

Increasing the overall volume increases Cardiac output, if overall cardiac output increases the central venous pressure increases OVERALL

530
Q

Why does vasodilation (decreased resistance) increase cardiac output when volume and central venous pressure are the same?

A

The resistance is lowered so the blood returns to heart faster. For each central venous pressure increases cardiac output due to increased flow back to heart

531
Q

Why does vasoconstriction (increase resistance) of central venous pressure decrease cardiac output

A

The resistance reduces blood flow back to the heart so for each venous pressure, the flow returning to heart is less and cardiac output is lowered

532
Q

How does gravity negatively affect cardiac output?

A

Gravity causes blood to pool in veins and venous pressure to increase in legs and ankles

533
Q

What are 4 components that drive venous return?

A

1.) Valves
2.) Skeletal muscle contraction
3.) Respiration
4.) Heart beat

534
Q

Describe the thoracic pump and how contributes to venous return

A

When inspiring, the pressure surrounding the lungs is decreased which pulls blood back toward the heart

535
Q

Describe how heart beats contribute to venous return

A

Each heartbeat pulls blood into the atria during systole due to high pressure in ventricles

536
Q

Maintenance of blood pressure at a minimum value is monitored:
Maintenance of blood pressure at a maximum value is monitored:

A

Moment to moment
Over time

537
Q

What is the most important neural reflex mechanism controlling blood pressure on a minute to minute basis?

A

Arterial baroreceptor reflex

538
Q

What do Atrial receptor reflexes do?

A

Considered low pressure receptors, sense volume
Regulate effective circulating blood volume and cardiac output
Indirect control
In place during dehydration and blood loss

539
Q

What are the 2 reflexes that maintain cerebral blood flow?

A

Cerebral ischemia reflex
Cushing reflex

540
Q

The arterial baroreceptor reflex provides ______________ feedback

A

Negative, so more stretching increases afferent activity to tell the brain decreases effector action

541
Q

Where are baroreceptors found?

A

Aortic arch and carotid sinus

542
Q

When arterial baroreflexes are stretch and afferent neurons are stimulated, when the response from brain goes to efferent neurons, the sympathetic and parasympathetic system are activated. Where is the Sympathetic system signaled? Where is the Parasympathetic system signaled?

A

From the nucleus of solitary tract:
Nucleus ambiguous corresponds to Parasympathetic
Caudal ventral lateral medulla to regulate sympathetic activity

543
Q

The carotid sinus and aortic arch have baroreceptors and chemoreceptors called:

A

Carotid bodies and aortic bodies

544
Q

Arterial chemoreceptors are activated by changes in:
1.) Decreased partial pressure ______
2.) Increased partial pressure ____
3.) _______ pH
Their stimulation causes an _______________ in blood pressure

A

O2
CO2
low
Increase

545
Q

Increasing the activity of the Nucleus ambiguous will increase _________________________. Which will:
1.)
2.)
3.)

A

Parasympathetic nervous system
1.) increase vessel diameter
2.) Decrease contractility
3.) Decrease HR

546
Q

Increase in BP:
1.)
2.) Increase afferent signaling to nucleus of the solitary tract
3.)
4.) Decrease rostral ventrolateral medulla
5.) Decrease sympathetic activity

A

1.) Stretches baroreceptors
2.)
3.) Increase activity to caudal ventral lateral medulla
4.)
5.)

547
Q

Why does chemoreceptor activation increase contractility, decrease vessel diameter with varied effects on heart rate?

A

Because activation of the chemoreceptors activates NTS which activates the Nucleus ambiguous so increase parasympathetic nervous system
AT THE SAME TIME
The RVLM is also increased directly so sympathetic activation is also increased

548
Q

The sympathetic nervous system innverates:
1.)
2.)
3.)
4.)
5)

A

Heart
Kidneys
vessels
adrenal medulla
arterioles

549
Q

T/F: The parasympathetic system innervates vessels to constrict vessel diameter

A

False
Parasympathetic does not innervate vessels

550
Q

Parasympathetic efferent neurons synapse:

A

Vagus nerve to induce heart changes

551
Q

Ach is release by POST ganglions of _________________________ to act on _______________________ receptors
Norepinephrine is released by POST ganglions of _____________________________________ in ___________________.

A

parasympathetic nervous system to act on muscarinic receptors
sympathetic nervous system to action on α & β adrenergic receptors

552
Q

Sympathetic preganglion that synapse in the adrenal medulla:

A

Induce release of norepinephrine and epinephrine to diffuse into blood stream for α & β adrenergic receptors

553
Q

Increased contractility:

A

Increases cardiac output

554
Q

The B 1 receptors increase:
1.)
2.)

A

Increase HR
Increase contractility (inc. cardiac output)

555
Q

T/F: The parasympathetic nervous system acts in exact opposite in reduce arterial pressure by reducing heart rate and contractility.

A

False, the parasympathetic NS only can decrease heart rate at the SA node

556
Q

In humans, the ___________________________ nervous system control of heart rate predominates at rest

A

Parasympathetic

557
Q

How does the sympathetic nervous system exert vascular effects?
How about parasympathetic effects on vasculature?

A

SNS: Alpha receptors are respondent to epinephrine and norepinephrine which to vasoconstrict with increases resistance
PSNS: None

558
Q

The Sympathetic nervous system innervates constriction to both arteries and veins. How does this raise BP?

A

Inc resistance of arteries, Inc Pressure
Increase venous tone, increases venous return to raise cardiac output

559
Q

When sympathetic NS releases norepinephrine to act on _______ receptors in the kidney, there is stimulation of ____________ secretion

A

β1 adrenergic receptors
Renin secretion

560
Q

What does renin do?

A

Inc. Angiotensin II

561
Q

Increased Angiotensin II:
1.)
2.)
3.)

A

1.) Inc plasma sodium which inc blood pressure
2.) Inc aldosterone, which inc. plasma sodium
3.) Vasoconstrictor to increase total peripheral resistance
4.) stimulate neurons that project into brain to increase SNS

562
Q

What does Aldosterone do?

A

Increases plasma sodium which can increase blood pressure

563
Q

T/F: Angiotensin II can act in the brain to increase Sympathetic nerve activity

A

Partly true, it cannot cross the blood brain barrier but Angiotensin II can be made in the brain to inc. SNS

564
Q

When arterial baroreflex sense drop in blood pressure, they can cause downstream effect of increase vasopressin. How does vasopressin increase blood pressure

A

1.) The vasopressin increases water reabsorption in the collecting duct
2.) Also acts as a vasoconstrictor

565
Q

Tonic _______ activity exerts tonic vasoconstrictor activity
The balance of tonic _______ and tonic ________ determines HR

A

SNS
PNS & SNS

566
Q

During total spinal anesthesia, the _______________ neurons action are removed which:

A

Efferent neurons
No tonic input and BP falls

567
Q

If PNS and SNS tonic activity is removed, can you increase arterial pressure?

A

Yes, by injecting norepinephrine to simulate Alpha and Beta adrenergic receptors

568
Q

How does hypertension occur if baroreceptors regulate blood pressure?

A

If there is prolonged arterial pressure increase, the baroreceptors will become tolerant to the high blood
BUT minute to minute regulation will still be in place

569
Q

In dogs, if baroreceptor responses are removed, what happens to pressure and mean arterial pressure?

A

The blood pressure has wide range but the mean arterial pressure stays the same due to CNS regulation

570
Q

Where are stretch receptors, AKA atrial receptors found?
What do they do?

A

Found in R atria, Type B firing
Detect Volume changes

571
Q

__________________ ________________ respond when end diastolic volume is too low or too high. They also fire when cellular ischemia is present. They exert effects via parasympathetic activity

A

Ventricular receptors

572
Q

What is the cushing response?

A

Increase SNS and endocrine response to increase blood pressure when there is elevated CSP pressure that has reduces blood flow by construction of blood vessels surrounding

573
Q

Why does heart rate decline with advanced age?

A

The β adrenergic mediation of increasing heart rate and signaling declines

574
Q

Describe how stroke volume is changed with advanced age

A

Preload is reduced: stiffening=reduced filling
Afterload is reduced: reduction of ejection fraction due to increased BP and widened pulse pressure

575
Q

What is ejection fraction?

A

Amount ejected from ventricle/mL contained in ventricle

576
Q

What contributes of afterload?

A
  • Vascular pressure (ventricular pressure must be higher than systemic to open aorta)
577
Q
A

Med Physiology Certificate (4 decks)

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