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PHTH 536 > Cardiovascular Anatomy and Physiology > Flashcards

Cardiovascular Anatomy and Physiology Flashcards

1
Q

Which arteries supply blood to the heart? What specific area?

A

1) right coronary artery
- right atrium and most of right ventricle, inferior wall of left ventricle
2) left coronary artery
- left anterior descending –> left ventricle, septum, inferior apex
- lateral circumflex –> lateral and inferior walls of left ventricle

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2
Q

What is the major vein that is part of the coronary circulation?

A

coronary sinus
- gets venous blood from the heart to atrium

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3
Q

Name the tissue layers of the heart (innermost to outermost)

A

1) endocardium
2) myocardium
3) pericardium
a) visceral - coronary vessels run through here
b) parietal
c) fibrous

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4
Q

List the 6 characteristics of myocardial structure

A

1) automatic, not voluntary due to pacemaker cells
2) influenced by the autonomic nervous system
3) external factors play a role (stress, exercise, caffeine, drugs)
4) contractile and conductive element of the heart
5) middle layer of heart wall
6) heavy oxygen demand through coronary arteries

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5
Q

Which nerve bundle that innervates the heart largely influences its parasympathetic activity?

A

vagus nerve bundle

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6
Q

What can cause vasovagal syncope (aka neurocardiogenic syncope)?

A

sight of blood, extreme emotions, overheating, noxious stimulus
- all can result in a decrease in heart rate and blood pressure which can cause fainting

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7
Q

List the 5 characteristics of the endocardium layer

A

1) thin, smooth layer of cells that lines the inside of the myocardium, atria, and valves
2) has some connective tissue, some elastic fibers and muscle fibers
3) provides a smooth surface to allow blood and platelets to flow freely and not adhere to walls
4) strengthens the valves and supports other heart tissue
5) supports the subendocardial layer which houses the Purkinje fibers

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8
Q

Name the two atrioventricular valves

A

1) tricuspid valve
- between right atrium and right ventricle
2) mitral valve
- between left atrium and left ventricle

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9
Q

Name the two semilunar valves

A

1) pulmonary valve
- right ventricle and pulmonary artery (bringing deoxygenated blood to lungs)
2) aortic valve
- left ventricle and aorta

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10
Q

List the order of blood flow through the cardiopulmonary system

A

deoxygenated blood flows through vena cava –> right atrium –> through tricuspic valve –> right ventricle –> through pulmonary valve –> pulmonary arteries –> lungs –> oxygenated blood flows through pulmonary veins –> left atrium –> through mitral valve –> left ventricle –> through aortic valve –> aorta –> body

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11
Q

What two components influence cardiac output?

A
  • heart rate and stroke volume
  • all 3 components can influence each other
  • when any of the 3 are altered, the other two compensate directly or need outside intervention to compensate
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12
Q

Define cardiac output

A
  • amount of blood ejected out of the left ventricle into the systemic vasculature per minute
  • at rest, takes about 4-5 minutes
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13
Q

Define stroke volume

A
  • amount of blood ejected by the left ventricle/beat
  • 55-100/beat
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14
Q

What 4 things affects stroke volume?

A

1) Left ventricular end diastolic volume (LVEDV) and end systolic volume (ESV)
2) Preload
3) Afterload
4) Contractility

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15
Q

Left ventricular end diastolic volume (LVEDV) and end systolic volume

A
  • the amount of blood left in the ventricle after diastole
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16
Q

Preload

A
  • the amount of stretch experienced by the sarcomeres pre-contraction
  • the greater the LVEDV the greater the stretch and volume pumped
  • directly proportional to stroke volume
  • affected by venous return and volume of returning blood
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17
Q

Afterload

A
  • force the left ventricle must generate to overcome aortic pressure to open aortic valve
  • inversely related to SV
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18
Q

contractility

A

the squeezing pressure of the left ventricle

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19
Q

Define ejection fraction (EF)

A
  • Percentage of blood emptied from the ventricle during systole
  • Useful way to understand left ventricular function
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20
Q

Ejection fraction equation

A

SV / LVEDV

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21
Q

What is considered a normal EF percentage?

A

<55%
- lower percentage means left ventricles are more damaged
- ex: for every 100 mL of blood poured into ventricles, 55 mL of blood is ejected

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22
Q

What does a low EF indicate?

A

heart failure or cardiomyopathy

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23
Q

Define myocardial oxygen demand

A

energy cost to myocardium

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24
Q

Sympathetic neurohumoral stimulation on heart

A
  • adrenergic (epinephrine/adrenaline and norepinephrine)
  • controlled in the medulla T1-T4
    SA node, AV, and conduction pathways
  • increases HR and force of myocardial contraction
  • coronary artery vasodilation
25
Q

Parasympathetic neurohumoral stimulation on heart

A
  • cholinergic
  • control in medulla through vagus nerve (CNX)
  • innervates SA and AV nodes
  • slows rate and force of myocardial contraction = decrease in myocardial contraction
  • coronary artery vasoconstriction
26
Q

Baroreceptors

A
  • pressoreceptors
  • in the walls of the aortic arch and carotid sinus
  • circulatory reflex: responds to blood pressure changes
    • increased BP –> parasympathetic stimulation, decrease rate and force of contraction, decrease work of heart
    • decreased BP –> sympathetic stimulation, increased HR and BP, vasoconstriction
27
Q

Chemoreceptors

A
  • located in the carotid body
  • sensitive to changes in O2, CO2, and pH which influences HR and RR
  • increased CO2 or decreased O2/pH –> increased HR and RR
  • increased O2 –> decreased HR
28
Q

hyperkalemia

A
  • increased concentration of potassium ions –> decreased HR, decreased contractile force, arrhythmias
  • EKG changes:
    • wider PR interval and QRS
    • tall T wave
29
Q

hypokalemia

A
  • decreased concentration of potassium ions
  • EKG changes
    • flattened T wave
    • prolonged PR intervals
30
Q

hypercalcemia

A
  • increased calcium concentration
  • increased HR and iontrophic effect (increased contractility)
  • also affected are kidneys, confusion, and coma
31
Q

hypocalcemia

A
  • decreased calcium concentration
  • may cause some arrhythmias
32
Q

hypermagnesmia

A
  • increased magnesium concentration
  • calcium blocker; arrhythmias or cardiac arrest; hypotension, confusion and lethargy
33
Q

hypomagnesia

A
  • decreased magnesium concentration
  • ventricular arrhythmias
  • coronary artery vasospasms
34
Q

Cardiac Cycle definition

A

the period from one heartbeat to the beginning of the next heartbeat

35
Q

action potential of heart beat

A
  • action potential starts at SA node and travels to the atria which spreads to the AV node
  • delay of about 0.1 second allows the atria to contract and ventricles to fill
36
Q

systole definition

A

period of contraction that the heart undergoes while it pumps blood into circulation

37
Q

diastole definition

A
  • period fo relaxation that occurs as the chambers fill with blood
  • coronary arteries perfuse the myocardium during diastole through capillaries
  • when the aortic valves closes shut, leftover blood is shunted to the coronary arteries
38
Q

What happens during Phase 1 of the cardiac cycle?

A
  • filling period
  • both atria and ventricles are relaxed
    (diastole)
  • blood is flowing into the right atrium from the vena cava and coronary sinus
  • blood flows into the left atrium from the pulmonary veins
  • both atrioventricular valves are open –> continuous blood flow from atria to ventricles
  • 70-80% of ventricular filling occurs by this method
  • both semilunar valves are closed - prevents backflow of the blood into the right and left ventricles from the pulmonary trunk on the right and the aorta on the left
  • SA node depolarizes –> atrial contraction
    • atrial systole
    • “atrial kick” remaining 2030% of ventricular filling
    • ventricular diastole
  • AV node depolarizes after 0.1 seconds delay and spread through the bundle of His
39
Q

Define end diastolic volume (EDV) or preload. How much preload is there at the end of atrila systole?

A

130 mL

40
Q

Phase II of Cardiac Cycle (isovolumetric contraction)

A
  • continued depolarization through the bundle branches and purkinje fibers creates a stronger ventricular contraction
41
Q

Phase III of Cardiac Cycle - Ejection

A

-pressure within the ventricles rise until greater than the pressure in the pulmonary trunk and the aorta, pushing open the pulmonary and aortic semilunar valves
- stroke volume
- still 50-60 mL of blood remaining in the ventricle following contraction (end systolic volume)

42
Q

What are the pleura of the lungs? What are the components?

A
  • two layered membrane that folds back on itself
  • cushions and lubricates the lungs during expansion and retraction
  • two types:
    • visceral (innermost)
    • parietal (outermost)
  • pleural cavity (analagous to the pericardial cavity)
    • pleural fluid: creates surface tension to keep the lungs in place in the thorax and allows the lungs to expand when the thorax expands; lungs collapse when this tension is lost
43
Q

What innervates the parietal pleura? And what does it sense?

A
  • phrenic and intercostal nerves
  • senses pain, temperature, and touch
44
Q

What is the mediastinum?

A
  • middle section of the thoracic cavity, between the left and right pleura
45
Q
A
46
Q

What are the three different types of pressures involved with breathing?

A

1) atmospheric: pressure exerted on the lungs by the outside atmosphere
2) intra-alveolar: the pressure exerted within the alveoli
3) intrapleural: the pressure within the two layers of the pleurae

47
Q

How do the lungs remain inflated?

A
  • elasticity of the lungs and surface tension of the alveoli create and inward pull
  • surface tension within the pleural cavity creates and outward pull (parietal pleura attached to the thoracic wall)
  • the outward pull is just slightly higher than the inward pull so the lungs stay inflated
48
Q

what is pulmonary ventilation?

A
  • air moving in and out of the lungs
  • inspiration and expiration –> one pulmonary cycle
49
Q

What happens during inspiration?

A
  • diaphragm contracts –> thorax expands inferiorly
  • external intercostals contract –> pulls ribs up and out –> expands thorax anteriorly
  • creates a pressure gradient and drives air into the lungs
50
Q

what happens during expiration?

A
  • largely passive
  • diaphragm and external intercostals relax and the elastic recoil of the lungs –> returns thorax to resting position –> reduces volume of thorax
  • creates a pressure gradient and drives air out of the lungs
51
Q

clinical application of mechanics of breathing

A

1) scoliosis: impairs the ability to the ribcage to expand which impairs the ability of the lungs to expand
2) pulmonary fibrosis: impairs compliance of lungs
3) COPD: overinflates lungs through air trapping (lungs can’t expel all the air that was inhaled) which impairs elasticity of lungs
4) asthma: increases resistance to airflow due to bronchoconstriction
5) premature babies (<7 months): reduced surfactant causes alveolar collapse
6) TBI: neural control of breathing

51
Q

What are the physical properties of the lungs that facilitate breathing?

A

1) lung compliance: distensibility of lung tissue (balloon)
2) tendency of lungs to recoil (collapse)
3) elastic recoil or elasticity: tendency of lungs to return to its original size after being distended
4) surface tension at air-liquid interface on the alveolar surface acts to collapse the alveoli; surfactant counters that
5) resistance to airflow at the level of the airways

52
Q

What areas of the brainstem control breathing?

A
  • medulla and pons
    • requires repetitive stimulation from the brain and nerve stimulation to muscles
53
Q

What drives respiration?

A

1) CO2 and pH levels in the blood; these stimulate central chemoreceptors in the medulla
- increase in CO2, pH decreases –> stimulates respiratory centers in medulla to contract the diaphragm and external intercostals –> increases rate and depth of respiration
- decrease in CO2 –> increase in pH –> respiratory centers to lower rate and depth of respiration
2) peripheral chemoreceptors in the carotid artery and aortic arch
- breathing is driven primarily by peripheral chemoreceptors for CO2 and O2
- increase ventilation in response to increasing level of CO2 in the blood
3) hypothalamus and limbic system

54
Q

What is Gas Exchange (Respiration)?

A
  • primary role of pulmonary system - get O2 in and CO2 out
  • occurs in the respiratory zone of the lungs toward the bottom of the lungs due to smaller but more abundant alveoli at the base
    • gas diffuses across membranes down a concentration gradient; driven by concentration of various gases in the air we breathe and blood pH
  • for effective gas exchange to occur alveoli must be both ventilated (air flowing in and out) and perfused (blood flowing into alveoli capillaries)
55
Q

What is the goal of gas exchange?

A
  • ventilation is matched to perfusion (V/Q match)
  • V/Q mismatch - pathological state
  • positioning can impact both ventilation and perfusion
  • not uniform: areas of the lungs with greater perfusion act as shunts and areas with greater ventilation are considered dead space
56
Q

transport of O2 and CO2

A
  • veins carry CO2 to lungs to expelled
  • arteries carry O2 from lungs to peripheral tissues
  • hemoglobin Hab (4 iron molecules - hemes and 4 protein molecules - globins)
    • exists in blood in various forms
      • oxyhemoglobin:nHab carrying O2
      • doxyhemoglobin: Hab that has released O2 to peripheral tissues
      • carbonxyhemoglobin: Hab bound to CO instead of O2
  • transports 98% of the O2 delivered to the periphery (2% plasma)
  • SaO2 - oxyhemoglobin/total hemoglobin (blood gas analysis)
  • O2 carrying capacity of body is determined by concentration of Hab
    • 12-16 g/dL women and 13-16 g/dl men
    • lower than normal concentration impairs body’s ability to circulate O2
57
Q

oxyhemoglobin dissociation curve

A
  • describes the relationship between SaO2 and the partial pressure of arterial O2 (PaO2)
  • not static

PHTH 536 (4 decks)

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