Cardiovascular Normal Function Part 1 Flashcards by Felita Salim

Flow of Blood

Deoxygenated blood enters ____ side of heart through systemic ____
Enters pulmonary circulation through pulmonary ____/_____ and becomes ______
Blood leaves through pulmonary ____ to the ____ side of the heart
Pumped into ______ circulation through systemic arteris that brings _____ blood to our organs at our systemic _____

Systemic Capillaries =

right, veins
arteries/capillaries, oxygenated
veins, left
systemic, oxygenated, capillaries

only sites of exchange between blood and tissue

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Flow of Blood through the Heart

Inferior and Superior Vena Cava -> RA -> Right AV valve (tricuspid) -> RV ->

Pulmonary artery -> Pulmonary capillaries to become oxygenated -> Pulmonary vein ->

LA -> Left AV valve (mitral) -> LV -> Aortic valve -> Aorta/Aortic Arch

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The Atrioventricular Valves

Right AV Valve =

Left AV Valve =

Valves exist between atrium and ventricles, ventricles and arteries but NOT between ____ and ____
Prevention of collapse (2)

Tricuspid Valve (3 leaflets)

Bicuspid “Mitral” Valve (2 leaflets)

Veins and atria
Strong rings of cartilage, Leaflets that fold inwards towards ventricles

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Ventricle Anatomy

Tendon cords that atach leaflets to the ventricle papillary muscle =
Valves are critical in order to maximize ____- to use in contraction of muscle to push blood into artery
Backflow represents =

Chordae tendinae
energy
wasted energy

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Aortic or Pulmonary valve “Semilunar Valves”

Difference from AV valves = these leaflets are true ____, forms little ____ -> so when valve is shut, blood fills these cups and participates in _____ off this valve

cusps, cups, sealing

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Pericardial Sac

2 sets of serous _____ that act as ______ sheets of _______ tissue that surround the heart

Epicardium =
Pericardium =
Pericardial Cavity =
Pericardial Fluid =

Function of the pericardial sac =

membranes, protective, connective

membrane that touches the heart
outside membrane that touches the tissue
space between the membranes
fluid inside the cavity

reduces frictional forces the heart has against other structures in the thoracic cavity

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Cardiac Muscle

Defining Features

(3)

Striated - linear lines made up of intracellular patterns that organize into striated lines (skeletal and muscle cells)

Branch Pattern of Cells - intercalated discs separate the diff cells creates branch pattern (only in cardiac muscle)

Intercalated Discs - gray lines that attach one cardiac muscle to the next - critically imp in function of the heart

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2 Key Structures of Intercalated Discs

Protein anchors that physically attach one cardiac muscle to the next Physically coupled

Electrical synapses between cardiac muscle cells where action potentials diffuse into the next Electrically coupled

Purpose of intercalated discs = _____ + _______ -> allows neighboring muscle cells to contract how?

Desmosomes

Gap Junctions

Physical Anchors + Electrically Coupled -> rapidly and all at once to act as a single unit

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Electrical Activity of the Heart

Two types of Specialized Cardiac Cells

__________ 99%
__________ 1%

Difference between the two?

Contractile Muscle Cells
Authorhythmic Cells

Pacemaker cells that are able to SPONTANEOUSLY generate action potentials at a particular frequency without external stimulation

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Cardiac Action Potential

Which Phase does this describe?

Rapid Depolarization: Opening of “fast” Na+ chanels
The “Plateau” phase; sustained by balance of Ca++ in and K out
Resting Membrane Potential
Closure of “fast” Na+ channels
Repolarization: Ca++ channels begin to close, K+ continues to flow out

Phase 0
Phase 2
Phase 4
Phase 1
Phase 3

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Cardiac Action Potential Notes

Does it spontaneously fire?

What is a defining feature?

Requires stimulation (does not spontaneously fire)

has a WIDER action potential (plateau phase) which allows neighboring cells enough time for action potential to spread so all can contract at the same time

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Autorhythmic Cells and the Pacemaker Potential

Membrane potential is never?
Lowest value is ___ for a brief time
Slow depolarization before threshold - caused by?
Within a few millivolts to threshold potential, what happens?
Once threshold hits, what causes the rising phase?
Rapid depolarization from?

No consistent (stable) membrane potential (is ever changing)
-60
greater amount of Leaking Sodium Channels
T-Type Ca Channel opens (transient that flickers open and close) trickles just enough Ca to get cell to threshold -40
L-Type Ca Channel (long type) stays open for longer
K out

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3 Locations of Autorhythmic Cells

Each has a different ____* of autorhythmic activity

SA node

AV node

R and L Bundle of His (Purkinje Fibers) located in the Intraventricular Septum

Rate*

SA node also has fibers that extend into LA

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Autorhythmic Cells

SA Node = __-__ action potentials/min

AV node = __-__ action potentials/min

Bundle of His and Purkinje Fibers = __-__ action potentials/min

70-80

40-60

20-40

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Autorhythmic Cells Notes

Different Natural firing rates are due to differing what?

__: node tends to depolarize from -60 up to threshold more quickly -> more action potentials per minute vs. bundles of His take longer to go up from -60 to threshold

Pacemaker of the heart? Why?

Duration of slow depolarization phase

SA node

SA node bc it sets the HR of the entire heart bc fastest firing frequency (fires before other group of cells gets a chance to , and when it does it quickly spread to rest of system)

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Spread of Cardiac Excitation

SA node -> (2) via (2) pathways simultaneously

AV nodal delay:

Purpose of the AV nodal delay?

SA node -> LA node via intra-atrial pathway and AV node via intranodal pathway

AV node fires action potential about 100msec

Allows for contraction of both atria at the same time to allow for Maximal ventricular filling

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Systole vs. Diastole

Systole =

Diastole =

Active contraction of the heart (both atria at once then both ventricles at once)

Period of rest between heartbeats

Electrocardiogram (ECG or EKG)

How many leads? Placed where?
Looks at the _______ electrical activity of the ____ heart

12 leads placed on surface of skin on chest and extremities
Composite, whole heart

PQRST Wave

P wave:
PR interval:
QRS complex:
ST interval:
T wave:
TP interval:

Depolarization of both Atria, generated by firing of the SA node
AV nodal delay
Depolarization of both Ventricles
Ejection of blood from ventricles/brief period of no activity
Repolarization of both Ventricles
Diastolic time between each heartbeat

Heart Changes associated with EKG

This pic of the cardiac cycle is showing the left side of the heart, everything thats happening here is also happening on the right side but what’s the difference?

Pressures are just smaller (0-20 instead of 0-120mmHg)

Steps of Heart Activity

(4)

Passive filling during ventricular and atrial diastole then Atrial Contraction

Isovolumetric Ventricular Contraction

Ventricular Ejection

Isovolumetric Ventricular Relaxation

Step 1

Firing of SA node -> depolarization of ______

Before the P wave in the EKG, what is happening?

Aortic Pressure =
LAP =
LVP =
LVV =

P wave: atrial contracts and pushes more blood into ventricles -> LAP, LVP, LVV all _____

PR interval =

Atria

Passive filling

80mmHG
Sits higher than LVP (green line)
Sits lower than LAP (red line)
Increasing as the ventricles are filling (valves are open) during asystole

Rise

AV nodal delay

Step 2

QRS complex =

LVP =
Heart Sounds =
LVV =

Depolarization of ventricles -> Contraction of Ventricles

increases drastically and is greater than LAP and eventually exceeds resting Aortic pressure so it can open valve and push blood into systemic circulation (has to get to above at least 80)
Closure of AV valves creates 1st heart sound when ventricles contract
Suddenly flatlines bc no more movement of blood into ventricles

Step 2 Notes

End Diastolic Volume
- ”___ phase of ventricles” Volume that is in the _____ at the end of _____, beginning of ventricular _____ -> represents extent of ventricular _____
Isovolumetric Ventricular Contraction
- ”contraction against a _____- volume” brief period of time it takes the ventricles to build up that ____ that exceeds ____ pressure to opent up aortic valve and all the valves are ____ at this time (steep red line)
T wave
- Apex of the heart is starting to ______,
- What happens to the valves when LVP goes back down below 80?

End Diastolic Volume
- Full phase, ventricles, diastole, contraction -> filling
Isovolumetric Ventricular Contraction
- Constant, pressure, aortic, OPEN
T wave
- relax
- CLOSURE of aortic and pulmonic when LVP gets below 80

Step 3 ## Footnote \_\_\_\_\_ Valve Opens -\> Ventricular Ejection * **LVV:** * **Aortic Pressure:** * **LVP:** * ****Where our BP reading comes from * 80mmHg = * 120mmHg =

Aortic * falls rapidly * rises bc it is getting this bolus of blood that expands the aortic wall (peaks at 120mmHg) * Higher than aortic pressure (red line) * Diastolic Aortic Pressure * Peak Systolic Pressure

Step 3 Notes ## Footnote * **End Systolic Volume** * **"\_\_\_\_\_ phase of ventricles"** volume at the end of systole (ventricular contraction) * **Stroke Volume** * ****volume of blood ejected by each _____ during a cardiac \_\_\_\_\_ * V important bc it represents volume of blood given to all _____ circulation to? * **SV = ____ - \_\_\_\_**

* **ESV** * **Empty phase** * **SV** * ****ventricle, cycle * systemic -\> perfuse organs * **EDV - ESV**

Step 4 ## Footnote **Period of time where LVP is below Aortic pressure but still above LAP, valves are all closed again "\_\_\_\_\_\_" - when ventricular pressur is falling against a constant pressure?** * T wave = Ventricles starting to \_\_\_\_\_ * T phase actually begins ____ ventricular contraction ends -\> portions of ventricles start to repolarize _____ (bottom of heart) and spreads upward toward _____ of heart * **LVP:** * **Heart Sounds:**

**Isovolumetric Ventricular Relaxation** * repolarize * before, apex -\> base * red line starts to fall below aortic pressure as ventricles start to relax during repolarization * 2nd heart sound due to closure of aortic and pulmonary valves

Step 5 ## Footnote * **LVP:** still falling and eventually falls below _____ pressure (green line) * Only when LVP falls below LAP will what happen? * **Dicrotic notch:**

* atrial * AV valves open up again -\> passive rush of blood into ventricles again * Reverberation of pressure as Aortic valve closes and blood bumps against walls of aorta

Step 6 ## Footnote "\_\_\_\_\_\_ phase" * Filling of the heart is mostly done as **\_\_\_\_\_\_\_ Filling** * **Atrial Kick:** * So why is most of the filling done passively? * During _______ _contraction,_ atria are still filling and the force of the contraction creates an expansion in volume of the atrea to create a _____ _like effect_ that draws in more blood (green line during peak of ejection phase)

"resting" * **Passive** * last little kick of blood that atrial contraction contributes to last bit of filling ~20% * _Ventricular, Suction_

Cardiac Performance and Control ## Footnote **Cardiac Output:** **CO = ____ x \_\_\_\_\_** = 70bts/min x 70ml/beat = about ___ Liters/min **Cardiac Reserve = ___ CO - ____ CO**

Volume of blood ejected from each ventricle per minute **HR x SV** 5L/min **Max CO - Resting CO**

Cardiac Performance and Control Notes ## Footnote Resting CO = Max CO = Max __ x Max \_\_ Max CO is a very individual # and primarily effected by? Max SV is a very VERY individual number effected by? Cardiac Reserve: In HF, cardiac reserve _____ -\> activity \_\_\_\_\_\_\_

5L/min HR x SV age exercise ie) athletes who are born with larger hearts narrows -\>intolerance

Control of Heart Rate ## Footnote HR is set by the? PNS -\> ______ HR SNS -\> ______ HR

**SA nodes** autorhythmic cells who are spontaneously active Decreases Increases

Parasympathetic Pathway ## Footnote PNS innervates the heart through the? * ____ vagus nerve innervates SA node more * ____ vagus nerve innervates AV node more **Vagal stimulation** of the heart does 2 things to **Decrease HR** 1. SA node firing slows down from release of \_\_\_\_ 2. AV nodal ____ is _____ (more time to fill ventricles with blood)

**Vagus Nerve** * Right -\> SA * Left -\> LA 1. Ach 2. AV nodal delay lengthens

Sympathetic Pathway ## Footnote **Sympathetic stimulation** for heart is through what? and also targets __ and __ node to _____ HR * Effects are the opposite 1. _____ SA node ____ rate 2. _____ AV nodal delay

**sympathetic postganglionic nerves** SA and AV node to **increase HR** 1. Increases SA firing 2. Decreases AV nodal delay

Control of Stroke Volume ## Footnote There are two mechanisms involved in altering SV 1. _____ control = 2. _____ control =

**Intrinsic Control** = increased filling **Extrinsic Control =** effects sympathetic stimulation to the heart (ionotropic)

Control of Stroke Volume Notes ## Footnote * **SV:** ______ of blood _____ with every heartbeat * Heart does not completely empty therefore we term the volumes **(2)** * **Ejection Fraction:** * SV is determined by **\_\_\_\_\_\_** of the heart 1. **Extrinsic control:** ____ stimulation increases contractility 2. **Intrinsic control:**"Frank Starling Relationship" aka Length Tension Relationship - the more you ____ the heart, the heart _____ more -\> can generate greater _____ of contraction

# * volume, ejected * **End systolic volume, End diastolic volume** * normal fraction of blood volume that is ejected with heartbeat is 55% * **Contractility** 1. ****SNS 2. fill -\> stretches -\> force Optimal length for generation of force in the heart is LONGER than the resting length of the heart - However if you go beyond optimal length (fills too much) force decreases bc its beyond optimal

Intrinsic Control ## Footnote Stroke Volume varies with End _____ Volume L\_\_\_\_- T\_\_\_\_\_ relationship Cardiac muscle length ___ than optimal at \_\_\_\_

Diastolic Length-Tension less than optimal at rest

Frank-Starling Law of the Heart ## Footnote (1) Increases -\> (1) Increases -\> (1) Increases

End Diastolic Volume -\> Force of Contraction -\> SV

Extrinsic Control of SV ## Footnote * Extrinsic Control by SNS nerves * In addition to direct innervation to SA and AV node -\> they also **directly innervate the ventricular \_\_\_\_\_** * **Enhanced SNS stimulation ventricular muscle = direct increase in ______ and generation of ____ -\> greater SV**

* **muscle** * **contractility, force**

Sympathetic Activity and Frank Starling ## Footnote * Intrinsic Control by changes in ______ filling * ______ changes of body can enhance venous return to heart -\> increase SV * Elevating \_\_\_ * Ex\_\_\_\_\_ * Usually Intrinsic Frank Starling relationship and Extrinsic are seen together * Purple line =

* venous * Positional * Legs * Exercise * Frank Starling (intrinsic) + SNS stimulation (extrensic) even bigger SV curve

CO Chart