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Physiology > Unit 8 > Flashcards

Unit 8 Flashcards

1
Q

Four Main Functions of the Heart

A
  • temperature and ph regulation
  • transporting oxygen and nutrients to all the cells in the body
  • transporting carbon dioxide and waste products out of the cell
  • transports and distributes hormones and other substances w/in the body
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2
Q

Anatomy: Two Side by Side Pumps

A
  • right atrium + ventricle: pumps blood to the lungs
  • left atrium + ventricle: pumps blood to the body
    • wall of the left ventricle is much thicker than the wall of the right ventricle.
    • why?
      • it pumps blood to the rest of the body and must contract more forcefully than the right ventricle which pumps blood to the ner by lungsts
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3
Q

What is the function of the valves in the heart?

A
  • valves in the heart ensure the one-way flow of blood through the heart.
  • Right atrioventricular valve (tricuspid)
  • Left atrioventricular valve (bicuspid or mitral valve)
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4
Q

Superior Vena Cava

A

delivers blood from the head + upper limbs to the heart

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5
Q

Pulmonary Artery

A

Blood leaving the right ventricle travels to the pulmonary artery

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6
Q

Aorta

A
  • Blood leaving the left ventricle travels through the aorta + is distributed through the entire body
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7
Q

Atria

A
  • Right atrium receives blood from the entire body
    • blood is low in oxygen + high in carbon dioxide.
    • the right atrium pumps blood into the right ventricle through the right atrioventricular valve (tricuspid)
  • Left Atrium
    • receives blood the has come from the lungs
    • blood is rich in oxygen and low in co2
    • the left atrium will pump blood into the left ventricle through the bicuspid valve.
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8
Q

Ventricles

A
  • Right Ventricle
    • receives blood from the atrium and pumps it into the pulmonary artery
    • pulmonary artery then delivers this blood to the lungs for gas exchange
  • Left Ventricle
    • receives blood from left atrium and pumps it into the aorta
    • aorta delivers the blood to the rest of the body.
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9
Q

Right AV valve (tricuspid)

A
  • ensures that the blood travels only in one direction, from the right atrium to the right ventricle
  • prevents blood from backing up into the atrium when the ventricles contract.
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10
Q

Left AV valve (bicuspid/mitral)

A
  • ensures blood travels only in one direction from the left atrium to the left ventricle
  • prevents blood from backing up into the atrium when the ventricles contract.
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11
Q

Pulmonary Semilunar Valve

A
  • Ensures that blood travels only in one direction
  • from the right ventricle to the pulmonary artery + prevents the blood from backing up into the ventricle when it relaxes
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12
Q

Aortic Semilunar Valve

A

Ensures blood travels only in one direction from left ventricle to the aorta and prevents the blood from backing up into the left ventricle when it relaxes.

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13
Q

Chordae tendineae

A
  • cords of collagen that attach to the valve at one end and to papillary muscles at the other
  • structures prevent the AV valve from being pushed into the atria when the pressure in the ventricle is high
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14
Q

Papillary Muscle

A
  • extension of the ventricular muscle attached to the chordae tendinaea.
  • when ventricles contract so do the papillary muscle the AV valves are held in place + don’t fold back into the atria
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15
Q

After flowing through the body blood enters the heart through the?

A

Right Atrium

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16
Q

From the _____ _____ blood is pumped through _____ _____ to the _____ _____.

A

Right Atria
tricuspid valve
Right ventricle.

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17
Q

Right Ventricle Contracts and Ejects Blood out of the heart through the _____ _____ and into the ______ ______

A

Pulmonary Valve

Pulmonary Artery

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18
Q

What happens to the blood in the lungs

A

CO2 is removed and oxygen is picked up by the blood

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19
Q

Blood returns through the _______ ______ to the ______ ______

A

Pulmonary Vein

left atrium

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20
Q

Blood flows from the _____ ____ through the _____ _____ to the ____ ____

A

left atrium
biscupid valve
left ventricle.

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21
Q

When the _____ _____ contracts blood is ejected from there to the _____ _____ and then the ______ out to the body

A

left ventricle
aortic valve
aorta

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22
Q

Two Types of Heart cells

A

Contractile cells

Nodal/Conducting Cells

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23
Q

Contractile Cells

A

Real muscle cells of the heart.

form most of the walls of the ventricles and atria

contain myofibrils made up of myosin and actin (tropomyosin;troponin), surrounded by SR.

contain 1 nucleus.

1/3 of volume consists of mitochrondria.

efficient in extracting oxygen (80% of O2 passing from the blood)

Shorter branched cells joined by intercalated discs.

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24
Q

Intercalated Discs

A
  • contain tight junctions that bind the cells together
  • gap junctions
    • allow for the movement of ions + ion currents between the myocardial cells
  • because of the gap junctions, the myocardial cells of the heart can conduct APs from cell to cell without the need for nerves.
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25
Q

Nodal/conducting cells

A
  • Similar to nerve cells
  • contract very weakly
    • contain very few myofibrils
  • cells can spontaneously generate action potentials without the help of nervous input like regular neurons (self-excitability)
  • they can also rapidly conduct action potentials to atrial and ventricular muscle
    • specialized cells provide a self-excitable system for the heart to generate impulses + a transmission system for rapid conduction of impulses throughout the heart.
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26
Q

Can all the cells in the heart generate action potentials?

A

Yes.

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27
Q

What is the site of origin of action potentials in the heart?

A
  • the SA node

- first area of the heart to spontaneously depolarize producing an AP.

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28
Q

Where is the SA node located?

A

In the upper posterior wall of the right atrium

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29
Q

The AP travels from the SA node to the ______ muscle causing it to contract

A

Atrial

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30
Q

The AP travels through the ____ to the ______-______ Node

A
  • Atria

- Atrio-ventricular node

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31
Q

The AP travels from the ____ node the _____ of ___ down the ____ of the heart

A
  • AV node
  • Bundle of His
  • Apex
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32
Q

From the ____ of ___ up to the _____ ____ which rapidly distribute the action potential to the ______ muscles which contracts the heart

A
  • Bundle of His
  • Purkinje Fibers
  • Ventrical
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33
Q

Is the speed of conduction of the action potential constant throughout the heart?

A
  • No!
  • SA node has the slowest conduction speed
  • AP speeds up in the atrial muscle to ensure that the muscles contract simultaneously
  • AP and consequently the whole muscle contraction travel from top to bottom
    • this ensures blood is forced down into the ventricles.
  • AV node slows down the conduction speed to ensure the atria have fully contracted before the. ventricles contract.
  • AP is conducted through the bundle of His at a very fast rate
    • it is important for the AP to reach the apex of the heart to contract first so that the blood can be forced up and out of through the valves at the top of the ventricle
  • purkinje fibers then spread the action potential throughout the ventricular muscles so it contracts from the apex upwards
    • fastest rate of conduction
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34
Q

Characteristics responsible for Nodal cell self excitability

A
  • slightly higher Na+ permeability than other cells
    • this makes the inside of the cell more positive over time (depolarized)
  • Ca++ is also trying to move into the cell.
  • Their movement causes the depolarization of the cell.
  • The movement of K+ is the main cause of the spontaneous action potential.
    • K+ wants to leave the cell (causing a hyperpolarization) but the permeability to K+ decreases over time causing less K+ to leak out.
  • The Na+/K+ pump is pumping K+ increasing the number of positive charges in the cell.
  • These factors will cause the depolarization of the cell.
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35
Q

Depolarization of the Nodal cell.

A
  • Membrane potential depolarizes to threshold (-40 mV)
    • special Ca++ gated channels will open
    • Ca++ floods into the cell producing a depolarization
    • Ca++ channels close and K+ channels will open releasing K+ ions out of the cell.
    • The movement of K+ ions out of the cell will repolarize the membrane to -60 mV
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36
Q

Pacemaker potential

A
  • Slow depolarization is completely spontaneous

- responsible for setting the pace of the heartbeat.

37
Q

Na+ and Ca++ are flowing in + K+ building up in the cell

A
  • membrane potential of the SA nodal cells depolarize from -60mV to -40 mV (threshold potential)
  • no stable resting membrane potential in SA nodal cells like neuron or muscle cells.
38
Q

Cardiac cycle (ECG)

A
  • P-Wave
    • depolarization of the atrial muscle leading to their contraction
    • no repolarizing wave (overshadowed by QRS complex)
    • QRS Complex
      • depolarization of the ventricular muscle just prior to its contraction
    • T-wave
      • repolarization of the ventricular muscle as it relaxes
39
Q

cardiac cycle consists of all the ______ + ______ ventricular events taking place in the heart during a single contraction

A
  • Mechanical

- Electrical

40
Q

Two primary phase

A
  • systole + diastole

- divided into smaller phases

41
Q

Pay attention to _ _ _ P_____ G_____, V_____ in the V_____ and A_____ of V_____

A
  • ECG
  • Pressure Gradient
    • blood flows from high pressure to low pressure
  • Volume in the ventricle
  • the activity of the valve
42
Q

Five Steps of the Cardial Cycle

A

Atrial Systole

Isovolumetric ventricular contraction (early ventricular systole)

Ventricular Systole (ejection period)

Early Ventricular Diastole

Late Ventricular Diastole

43
Q

Atrial Systole

A
  • the first phase begins with the depolarization of the atria (P-wave in ECG)
  • Atria contracts
  • atrial pressure is greater than ventricular pressure
  • The AV/mitral valve opens and blood flows from the atria to the ventricle
  • ventricle volume increases slightly (end diastolic volume)
    • volume before the ventricle contracts.
44
Q

Isovolumetric ventricular contraction (early ventricular systole)

A
  • ventricles depolarize (QRS complex)
  • ventricular pressure increases rapidly (above atrial but below aortic)
  • the mitral valve closes
  • no change in ventricular volume
45
Q

Ventricular Systole (ejection period)

A
  • ventricles are still contracting but new ventricular pressure is above aortic.
  • aortic valve opens
  • blood flows into the aorta, ventricular volume decreases
46
Q

Early Ventricular Diastole

A
  • ventricular pressure falls below aortic pressure
  • aortic valve closes
  • some blood remains in the ventricle (end-systolic volume)
  • ventricular pressure continues to fall
  • no change in ventricular volume
47
Q

Late Ventricular Diastole

A
  • ventricular pressure drops below atrial pressure
  • mitral valve opens
  • ventricular volume increases
  • p-wave begins, the cycle repeats
  • 80% of blood volume from the atria flows to the ventricles
48
Q

Which phase gives the greatest contribution of blood to ventricular filling _____ _____ ______?

A
  • most of the blood enters the ventricles when they relax (during late ventricular diastole)
    • blood flows passively into the ventricles when the pressure in the atria exceeds the pressure in the ventricles
  • atrial contraction during atria systole only contributes 20-30% of ventricular filling.
  • this pressure gradient begins during the late ventricular diastole when the ventricles are relaxing and continue until the atria have finished contracting
49
Q

in order for blood to be ejected from the heart, the ______ in the _______ must be _______ than the ______ in the _____.

A
  • pressure
  • ventricles
  • greater
  • pressure
  • aorta
50
Q

when the pressure in the left ventricle rises to _____ mmHg (which is the pressure in the aorta) the _____ ______ opens

A
  • 80
  • aortic valve
    blood pours out of the ventricles while the pressure continues to increase to 120 mmHg
51
Q

Ejection period

A

ventricles empty blood into the aorta

52
Q

Heart Sounds

A

when they close, the vanes of the valve and the surrounding fluid vibrate under the influence of sudden pressure differences, producing sounds that travel in all directions

53
Q

First Heart Sound (LUB)

A
  • produced indirectly by the closure of AV valves
    • low pitched
    • relatively long duration
54
Q

Second Heart Sound (DUB)

A
  • produced by the closing of the aortic/pulmonary valves
  • high pitch
  • shorter duration
55
Q

What are aspects of the mechanical performance of the heart?

A
  • How much blood it can pump at rest or during exercise
  • how to calculate how much it pumps
  • mechanisms that contol its pumping capacity
56
Q

Cardiac ouput is the _______ ___ _____ each ______ can pump in _____ minute

A
  • Amount of blood
  • ventricle
  • one
57
Q

At Rest Cardiac output is?

A

Five liters of blood per minute

58
Q

Vigorous exercise

A
  • 20L/min (normal person)
  • 35-40L/min (trained athlete)
  • During exercise the CO increases dramatically in order to supply the working muscles with more oxygen + nutrients
59
Q

Equation for CO

A

CO = Heart Rate (bpm)xStroke Volume (L)

60
Q

Heart Rate

A

the number of times the heart beats in 1 minute

61
Q

Stroke Volume

A
  • amount of blood pumped by one ventricle during one contraction (heartbeat)
62
Q

_ _ _ controls heart rate + force of contraction. The heart is innervated by both the _ _ _ _ and the _ _ _

A
  • ANS (Autonomic nervous system)
  • PYNS (parasympathetic nervous system)
  • SYN (Symapthetic nervous system)
63
Q

_ _ _ _ nerves are distributed mainly to the _ _ and _ _ nodes and to a lesser extent ______ and _____ muscles.

A
  • PYSN
  • SA
  • AV
  • Ventricular
  • Atrial
64
Q

_ _ _ nerves are distributed to the same areas but with a stronger innervation in the _____ muscle

A
  • SYN

- Ventricular

65
Q

PYSN decreases _____ ______ through the SA and AV nodes and to a lesser extent the _____ ___ ______

A
  • Heart Rate

- force of contraction

66
Q

Natural heart rate (no influence of ANS)

A

100 bpm

67
Q

Resting Heart Rate, why is it different from the natural heart rate?

A
  • 70 bpm

- activity of the PYSN is always on keeping the heart rate slowed.

68
Q

When PSYN neurons to the heart are activated they release ________ onto the SA and AV node

A

Acetylcholine

69
Q

___ causes _ channels to open letting more _ out of the cell resulting in __________ and the slope of the pacemaker potential _______

A
  • Ach
  • K+
  • hyperpolarization
  • decreases
70
Q

Membrane potential will take _____ to reach threshold and heart rate will? (PSYN)

A
  • longer
  • slow down
  • SA node potential will last longer
  • slows down the heart rate
71
Q

PSYN affects the AV node _____ by releasing acetylcholine

A
  • similarly
  • the AV node must decrease as well
    • to ensure the atria have finished contracting before ventricles contract.
72
Q

___________ is realeased by nerves of the SYN onto the SA node causing the opening of _ _ and _ _ channels allowing more of these ions to enter SA nodal cells resulting in a more rapid ________

A
  • Norepinenephrine (adrenaline)
  • Ca++
  • Na+
  • depolarization
73
Q

Stroke Volume EQUATION

A

SV = EDV - ESV

Any change in EDV or ESV will alter the SV and thus the CO.

74
Q

EDV

A
  • End Diastolic Volume

- amount of blood in the ventricle at the end of diastole just before it contracts

75
Q

ESV

A
  • End Systolic Volume

- Amount of blood in the ventricle just after it contracts

76
Q

_______ ___ ______ of the heart determines stroke volume

A
  • Force of Contraction

- whatever changes force of contraction will change stroke volume.

77
Q

three things can alter stroke volume

A
  1. Input from the ANS (PYSN or SYN)
  2. EDV + Preload
  3. ESV
78
Q

Control of stroke volume by PSYN: _______ the force of contraction of the heart by releasing acetylcholine onto the ______ ______

A
  • decreases
  • cardiac muscle

Decreases the amount of calcium entering into the muscle cell.

  • This decreases the force of contraction
    • decreasing SV and CO
79
Q

Control of stroke volume by SYN: Releases ___________ onto the _____ ____, leading to a more forceful contraction + increasing stroke volume

A

norepinephrine

cardiac muscle

80
Q

Preload

A
  • load on the heart just before it contracts
  • related to the EDV
  • Comes from the blood in the ventricle that stretches the muscle of the heart
  • the more blood in the ventricle the higher the load + EDV
81
Q

Charging EDV and Preload: stretching causes special _ _ channels in the cardiac muscle cells to open allowing _ _ into the cell.

A

Ca++

82
Q

The higher the _ _ content in the cell the more forceful the contraction, the more blood ejected during systole.

A
  • Ca++

- the more blood ejected the lower the ESV.

83
Q

Frank-Starling Law of the heart

A

Increases in EDV result in an increase in stroke volume

84
Q

Changing the EDV

A

Increasing the EDV means filling the heart with more blood before it contracts

85
Q

Increase the EDV by ________ the ____. Why?

A
  • squeezing
  • veins
  • Veins contain 70% of the total blood volume of the body
  • veins have valves ensuring one-way blood flwo
    • squeezing the veins will increase the veinous return of blood to the heart increasing EDV.
86
Q

_ _ _ innervates smooth muscle located in the walls of ______

A
  • Veins
    • SYN
  • muscle forms a ring around the inside of the vessel wall, when it contracts it causes the veins to constrict and w/ the help of valves squeezes blood bac to the heart
  • increases venous return, increases EDV
    • Increasing the SV + CO
87
Q

Changing EDV by Exercise: Repeated contraction + relaxation of _______ _______ squeezes veins

A

skeletal muscle

88
Q

Veins between large groups of muscle

A

dynamic forms of exercise can repeatedly squeeze veins pumping blood back to the heart.

Physiology (12 decks)

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