Lecture 1: Introduction Flashcards

1
Q

what is contained in the thoracic cavity

A

ribs
sternum
T/S vertebrae
Heart
lungs
upper abdominal organs

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2
Q

what is contained in the mediastinum

A

all thoracic viscera except lungs

heart
cardiac vasculature
esophagus
trachea
thymus
thoracic duct/lymph structures
phrenic nerve
cardiac neural structures

contents can shift around

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3
Q

location of mediastinum

A

between lung pleurae

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4
Q

basic anatomy/location of heart

A

size of closed fist

apex at 5th intercostal space of midclavicular line

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5
Q

3 tissue layers of heart

A

pericardium = outer layer/ “sac”
myocardium = muscular layer
endocardium = inner layer “lining”

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6
Q

describe the pericardium

A

triple walled sac that contains heart

layers:
- fibrous pericardium = outermost; anchored to diaphragm
- parietal layer = provides lubrication
- visceral layer (epicardium) = contains coronary vessels on heart surface

pericardium has 10-20mL pericardial fluid within pericardial cavity that decreases friction throughout cardiac cycle

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7
Q

describe the myocardium

A

heart muscle

various thickness in different chambers

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8
Q

describe the endocardium

A

inner lining of heart

simple squamous endothelium

valves and chordae tendinae

contains electrical components

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9
Q

function of right atria

A

receives deoxygenated blood from venae cave

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10
Q

function of left atria

A

receives oxygenated blood from pulmonary veins

thicker walls to accommodate for higher pressure of blood coming from pulmonary circulation

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11
Q

describe atria in general

A

separated by interatrial septum

contain auricles to increase available capacity as needed

pectinate muscles contribute to strength of atrial contractions

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12
Q

right ventricle function

A

receives deoxygenated blood from R atria via tricuspid valve

sends blood to lungs via pulmonary valve and arteries

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13
Q

left ventricle function

A

receives oxygenated blood from L atrium via mitral valve

sends blood to body via aortic valve and aorta

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14
Q

general structure of heart valves

A

unidirectional flow

leaflets attached to papillary muscles via chordae tendinae

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15
Q

function of atrioventricular valves

A

prevents back flow during ventricular contraction

AV valves = tricuspid and mitral (bicuspid)

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16
Q

function of semilunar valves

A

prevent back flow during ventricular relaxation

SL valves = pulmonary and aortic

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17
Q

when do coronary arteries receive blood

A

during ventricular relaxation while aortic valve is closed

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18
Q

branches of L coronary artery and where those branches supply blood to

A

L anterior descending = anterior L ventricle, anterior 2/3 IV septum, and small part of R ventricle

Circumflex = L atrium, posterolateral L ventricle, SA node (40%), and Bundle of His

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19
Q

branches of L anterior descending artery (widow maker)

A

diagonal
septal branches
endocardial

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20
Q

branches of cirfumflex artery

A

posterior L ventricular

L obtuse marginal

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21
Q

branches of R coronary artery

A

R marginal artery

R posterior descending

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22
Q

where does R coronary artery supply

A

R atrium
SA node (60%)
AV node

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23
Q

where does the R marginal artery supply blood

A

Lateral R ventricle

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24
Q

where does the R posterior descending artery supply blood

A

inferior L ventricle

posterior 1/3 IV septum

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25
Q

what is coronary dominance

A

designates the coronary artery system that is responsible for majority of the posterior L ventricular circulation

R dominant (most common) = R coronary aa gives off posterior descending aa

L dominant = circumflex gives off posterior descending aa

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26
Q

superior vs inferior vena cava collect venous blood from

A

superior = upper body and head

inferior = lower body and trunk

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27
Q

where do coronary arteries arise from

A

off aortic sinus of Valsalva

28
Q

aortic arch gives off what

A

3 arteries that supply BUE and head

29
Q

descending aorta bifurcates into

A

B iliac arteries

descending aorta = highest BP in body

30
Q

list the path of blood flow starting with the venae cavae

A

venae cava
R atrium
tricuspid valve
R ventricle
Pulmonary valve
pulmonary artery
lungs
pulmonary veins
L atrium
mitral valve
L ventricle
Aortic valve
aorta
systemic circulation

31
Q

compare/contrast arteries vs veins

A

arteries
- oxygenated blood away from heart
- thicker walls

veins
- deoxygenated blood to heart
- thinner walls
- large diameter
- valves prevent back flow

capillaries = O2/CO2/nutrient exchange

32
Q

describe the layers of blood vessels

A

tunica intima = inner layer; epithelial cells

tunica media = smooth mm

tunica adventitia/externa = outer layer; collagen and elastin

33
Q

describe the cell makeup of the myocardium

A

cardiac myocytes = connected mechanically and electrically

sarcomeres have actin and myosin filaments for contractility (force of contraction correlated with Ca++ available for binding)

very high # mitochondria (50% myocardial mass); high ATP production

34
Q

describe the physiology behind contractions in the heart

A

Na-K pump maintains AP and keeps more Na outside cell and more K inside

Ca binds to myocardial filaments to induce contraction

sarcoplasmic reticulum absorbs Ca and causes relaxation

increase in Ca = increase contractility = higher HR

myoglobin stores O2 during diastole and releases O2 during systole

35
Q

characteristics of myocardium

A

automaticity = pacemaker abiltiity

conductivity = conducts impulses to one another

contractility = shorter or longer

irritability = contract on their own and/or send impulses without first being stimulated from another source

36
Q

describe the function of the sympathetic portion of the cardiac plexus

A

increase HR

increase contractility

coronary aa vasodilation

37
Q

describe the function of the parasympathetic portion of the cardiac plexus

A

decrease HR

decrease contractility

SA node controlled by R vagus

AV node controlled by L vagus

38
Q

describe the 3 sympathetic cardiac receptors

A

Adrenergic (alpha 1) = causes peripheral vasoconstriction (increase SVR); epi and norepi

beta 1 = cause increased HR and SV

beta 2 = cause pulmonary and peripheral vasodilation (decrease SVR)

39
Q

describe the parasympathetic cardiac receptor

A

muscarinic = decrease HR

acetylcholine

40
Q

purpose/conduction of the SA node

A

“pacemaker”

60-100 bpm pace

in R atrium near superior vena cava

41
Q

action of cardiac receptors

A

a1 = vasoconstriction = increased systemic vascular resistance

b1 = increase HR and SV = increase CO

b2 = vasodilation = decreased SVR

42
Q

purpose of AV node

A

“gate keeper”

40-60 bpm internal pace

between intertribal and intraventricular septum

43
Q

describe the path of electrical conduction of the heart

A

SA node generates AP

impulse to R and L atrium and mm contracts

impulse to AV node; slows due to Ca++; ventricles fill

impulse to Bundle of His in intraventricular septum

impulse to R and L bundle branches; depolarizes ventricles and causes ventricular contraction

to Purkinje fibers where electrical activity spreads from endocardium to epicardium

44
Q

what is a cardiac cycle

A

one cycle of atrial and ventricular contraction

systole = contract

diastole = relax

45
Q

list the phases of systole/diastole and what is happening with each

A

atrial systole = blood ejected to ventricles

atrial diastole = atra relaxed; prepare for next fill cycle

early ventricular systole = AV valves close, but not enough pressure to open SL valves

late ventricular systole = SL valves open and blood is ejected

early ventricular diastole = drop in pressure closes SL valves

late ventricular diastole = all chambers closed; passive ventricular filling

46
Q

normal sounds of heart

A

S1 “lub” = closure of AV valve in early ventricular systole; peak of R wave

S2 “dub” = closure of SL valves; termination of ventricular systole and start of ventricular diastole; end of T wave

47
Q

P wave indicates what

A

atrial contraction

48
Q

PR segment indicates

A

ventricular filling

49
Q

QRS complex indicates

A

ventricular contraction

50
Q

ST segment indicates

A

plateau phase of ventricular relaxation

51
Q

T wave indicates

A

ventricular relaxation

52
Q

what is stroke volume

A

volume of blood ejected per contraction

53
Q

what is cardiac output

A

volume of blood ejected from L ventricle per minute

4-6 L/min

54
Q

equation for cardiac output

A

CO = HR x SV

55
Q

factors that affect cardiac output

A

preload = how full is the tank

contractility = how good is the squeeze

afterload = how loose is the vasculature

56
Q

preload

A

degree to which heart mm can stretch before contraction

correlated to end diastolic volume (EDV) - max amount of blood returning to heart

directly proportional to stroke volume; more blood that returns to the heart the greater volume that can leave

57
Q

what is frank starling law

A

states that greater volume of blood is ejected when a greater volume returns

if myocardial fibers are too stretched or shortened, contraction strength is decreased

58
Q

contractility

A

ability of ventricles to contract to send blood to lungs and periphery

increase in HR = increase contractility

in HR > 120 there is an increase in Ca++ resulting in stronger contraction

reflected by ejection fraction

59
Q

what is ejection fraction

A

best indicator for cardiac function

ratio of volume of blood ejected vs volume received prior to contraction

some blood must remain in ventricles to maintain certain degree of stretch

60
Q

what is after load

A

force that resists contraction

pressure within the arterial system during systole

expressed as systemic vascular resistance (SVR) or total peripheral resistance (TPR)

increase in after load = decrease in stroke volume and decrease in cardiac output

61
Q

what is cardiac index

A

measure of how well heart is functioning

more individualized than cardiac output or ejection fraction

correlates blood volume pumped by heart to body surface area

normal is 2.5-4.0 L/min/m^2

if CI falls below 2.2 pt is likely in cardiogenic shock

62
Q

describe how venous return works

A

venous pressure <arterial pressure

distal venous pressure > proximal

these things allow for gradient of blood flow back to heart

during inhalation, increased abdominal pressure creates vacuum in thoracic cavity pulling blood back to heart

63
Q

what does the oxyhemoglobin dissociation curve show

A

relationship between amount of O2 bound to Hgb

ability of RBCs to release O2 to tissues that need it most

64
Q

what is relevant about SpO2 of 90%

A

90% = PaO2 of 60mmHg

this is the minimum O2 concentration needed to prevent ischemia in tissue

65
Q

what does a L shift on the oxyhemoglobin dissociation curve indicate

A

Hgb holds onto O2 since tissues don’t need it

more O2 bound to Hgb

lower partial pressure O2

lower temp and mm work

higher blood pH (less acidic)

66
Q

what does a R shift on the oxyhemoglobin dissociation curve indicate

A

releases O2 to tissues that need it more

less O2 bound to Hgb

naturally happens during exercise

higher temp and mm work

lower blood pH (more acidic)

67
Q
A