Cardiopulmonary Anatomy and Physiology Flashcards
What does the Right Coronary Artery supply
- Right Atrium
- Right Ventricle
- Inferior wall of the Left Ventricle
- AV node, SA node in (60% of people), and bundle of his
What does the Left Coronary Artery branch into
- The Left Anterior Descending
- The Left Circumflex
What does the Left Anterior Descending supply
- left ventricle
- intraventricular septum
- Right ventricle
- inferior apex
- Inferior angles of both ventricles
What does the left Circumflex supply
-lateral and inferior walls of the left ventricle
- SA node in 40% of the population
- left atrium
what are the tissue layers of the heart from innermost to outermost?
- Endocardium
- Myocardium
- Visceral Pericardium
- Parietal pericardium
- Fibrous Pericardium
what layers of the pericardium is the pericardial fluid found between
in the pericardial cavity between the visceral and parietal layers
What is the myocardium
Layer of heart muscle tissue that is striated and is able to contract without conscious voluntary control
What is the Myocardium influenced by?
- Both the sympathetic and parasympathetic (vagus) pathways of the autonomic nervous system
- Some voluntary control over the heart rate through breathing techniques
- Vasovagal Scope
- External factors such as stress
- Contractile elements of the heart
- Conductive elements of the heart
- Middle layer of heart (pericardium, myocardium, endocardium)
- Heavily O2 demanding through the coronary arteries
What is the structure of the endocardium
- Thin, smooth layer of cells lining the inside of the myocardium, values, and atria
- Has some connective tissue, some elastic fiber and muscle fibers
What is the function of the endocardium
- Provides a smooth surface to allow blood and platelets to flow freely and not adhere to heart wall
- Strengthens the valves and supports other heart tissues
- Supports the subendocardial layer which houses the purkinje fibers
what are the 2 types of heart valves
1) Atrioventricular (AV) valve
2) Semilunar valve
what are the two AV valves?
1) tricuspid (right atrium and right ventricle)
2) mitral (left atrium and left ventricle)
Pathway of the blood of deoxygenated blood
Deoxygenated blood through vena cavea - right atrium - tricuspid valve - right ventricle - pulmonary valve - pulmonary artery - lunges
Pathway of the blood in the oxygenated blood
Oxygenated blood through the pulmonary veins - left atrium - mitral valve - left ventricle - aortic valve - aorta - body
what valves are open in diastole
tricuspid valve and mitral valve
what valves are open in systole
pulmonary valve and aortic valve
what is the equation for Cardiac Output
CO=HR x SV
what is Cardiac Output?
The amount of blood that is ejected out of the left ventricle into the systemic vasculature/ minute
what is the normal cardiac output at rest
4-5 L/minute
normally takes a volume of blood about 1 minute to travel through the pulmonary and systemic circuits
what is stroke volume?
the amount of blood that is ejected of the left ventricle/ beat
what is the normal stroke volume values?
55-100 ml/beat
what is stroke volume affected by
1) preload
2) afterload
3) contractility
Preload
- the amount of stretch experienced by the cardiac sarcomeres pre-contraction
- the greater the LVEDV the greater the stretch and volume pumped (starling’s law) and the greater the preload
- affected by venous return and volume of returning blood
Afterload
- Force left ventricle must generate to overcome aortic pressure to open the aortic valve
- the resistance on the ventricle
- inversely related to SV
Contractility
the squeezing pressure of the left ventricle
what else is the stroke volume affected by
The left ventricular end diastolic volume (LVEDV) and end systolic volume (ESV)
what is the ejection fraction
- percentage of blood empties from the ventricle during systole
- useful in knowing left ventricular function
- volume of blood ejected (SV) relative to the volume of blood received before contraction (LVEDV)
what is the equation of the ejection fraction (EF)
EF=SV/LVEDV
what is the average percentage of ejection fraction
greater then 55% (60-70%)
what is a low EF an indicator of
Cardiomyopathy or heart failure; impairment of the left ventricle
what is the myocardial O2 demand
- HRxSBP produces rate pressure product
- Increases with activity and HR and/or BP
what is preload impacted by
- end-systolic volume
- venous return
what impacts afterload
- aortic pressure
- aortic valvular function
what impacts contractility
- end diastolic volume
- sympathetic stimulation
- myocardial O2 supply
what impacts heart rate
- CNS
- Autonomic nervous system
- Neural reflexed
- Atrial receptors
- Hormones
what are the neurohumeral influences on sympathetic stimulation (adrenergic)
- control of the medulla via T1-T4
- SA node, AV, conduction pathways, impacted by adrenergic system
- increases HR and force of myocardial contraction = increase in myocardial oxygen demand
- coronary artery vasodilation
- sympathomimetics; antihypertensives and sympathetic blockers
what are the neurohumeral parasympathetic stimulation (cholinergic)
- control in the medulla via the vagus nerve, cardiac plexus
- innervates the SA and AV nodes
- slows rate and force of myocardial contraction = decrease in myocardial contraction
- coronary artery vasoconstriction
baroreceptors
pressure receptors that are found in the walls of aortic arch and carotid sinus
what is the circulatory reflex
respond to blood pressure changes
increased BP - parasympathetic stimulation: decrease HR, force of contraction, and peripheral resistance
decreased BP - sympathetic stimulation, increased HR and BP, vasoconstriction
Chemoreceptiors
- located in the carotid body
- sensitive to changes in O2, CO2 and lactic acid pH and will affect HR and RR
what does an increase in CO2 or decrease in O2 or pH lead to
increased HR and RR
what does an increase in O2 lead to
decreased HR
Hyperkalemia
increased concentration of K+ ions leads to a decrease in HR, decrease in contractile forces, arrhythmias, and EKG changes
what would you see on an EKG of a pt with hyperkalemia
widened PR interval and QRS, tall T waves
Hypokalemia
decreased concentration of K+ ions, EKG changes
what would you see in an EKG of a pt with hyperkalemia?
flattened t waves, prolonged PR intervals
Hypercalcemia
increased calcium concentration leading to an increase in HR and + inotrophic effect (contractibility). Often kidneys affected, confusion, and coma
Hypocalcemia
a decrease in calcium concentration that may lead to arrhythmias
Hypermagnesmia
increased magnesium concentration it is a calcium blockers that can lead to arrhythmias, cardiac arrest, hypotension, confusion and lethargy
Hypomagnesmia
decreased magnesium concentration leading to ventricular arrythmias and coronary artery vasospasm
what is the cardiac cycle
- the period from one heartbeat to the beginning of the next heartbeat
- Action potential starts at the SA node, depolarized the atria, spreads to the AV node
Systole
the period of contraction that the heart undergoes while it pumps blood into circulation
Diastole
the period of relaxation that occurs as the chambers fill with blood
Cardiac Cycle Phase I - the filling period
- blood flows into the left and right atrium with both tricuspid and mitral valves open allowing blood to flow into the ventricles
- SA node depolarizes allowing for a atrial contraction for ventricular filling
- AV node depolarizes and sends signals to the bundle of his
- pressure of the ventricles starts to rise causing the closing of the tricuspid and mitral valves
Cardiac Cycle Phase 2- Isovolumic contraction
- continued polorization of the bundle branches and perkinjie fibers create a stronger ventricular contraction
Cardiac Cycle phase 3 - Ejaction
- Pressure in ventricle > then pressure in pulmonary trunk and aorta pushing the semilunar valves open
- ventricular relaxation or diastole follows repolarization of the ventricles
Cardiac Cycle phase 4 - Isovolumentric ventricular relaxation phase
- ventricles continue to relax and pressure of in the ventricles drops
- tricuspid and mitral valves begin to reopen
what are the 2 pleurae of the lung
- the visceral innermost layer
- parietal outermost layer
what is the space between the visceral and the parietal pleura called
the pleural cavity/pericardial cavity
what is the purpose of the pleural fluid
- creates surface tension to keep the lungs in the thorax
- allows the lungs to expand when the thorax expands
- cushions and lubricates the lung during expansion and retraction
what is the parietal pleura of the lungs innervated by
the phrenic and intercostal nerves (can sense pain, temperature and touch)
Accessory muscles of inspiration
- SCM
- Scalene
Principal muscles of inspiration
- External intercostals
- Diaphragm
Muscles of experation
- Internal intercostals
- External obliques
- Rectus Abdominis
- Transversus Abdominis
- Internal obliques
what are the 3 different types of pressure that contribute to breathing
1) atmospheric
2) intra-alveolar
3) intrapleural
what are the competing forces of pressure that keep the lungs inflated
1) inward pull: elasticity of the lungs and the surface tension of the alveoli
2) outward pull: surface tension within the pleural cavity
what pull is slightly higher to keep the lungs inflated
the outward pull from the pleural cavity
What happens to size of the thorax during inspiration
- diaphragm contracts expanding the thorax inferiorly
- External intercostals pull the ribs up and out expanding the thorax anteriorly
what happens to the size of the thorax during expiration
- diaphragm and external intercostals relax causing the volume of the thorax to decrease expelling air out.
what are the physical properties of the lungs that facilitate breathing
1) lung compliance (distensibility of tissue)
2) Tendency of the lungs to recoil
3) elastic recoil or elasticity
4) surface tension at the air-liquid interface on the alveolar surface
5) Resistance to airflow at the level of the airways
what part of the brain controlled breathing?
medulla and the pons
what drives the RR in the medulla and pons
changes in CO2 and pH levels in the blood
what happens as CO2 concentration increases in the blood
pH decreases in blood, stimulates respiratory centers in medulla to contract diaphragm and external intercostals, increases rate and depth of respiration
what happens as CO2 concentration decreases in the blood
pH increases, causes respiratory centers to lower the rate and depth of respiration
what is hypercapnia
increasing ventilation in response to increasing levels of CO2 in blood
what is hypoxia
increasing ventilation in response to decreasing levels of O2 in the blood
where does gas exchange occur
in the respiratory zone toward the bottom of the lungs where there are more abundant alveoli
what is the V/Q match
when ventilation (V) is the same as perfusion (Q)
what do areas of the lungs with greater perfusion act as
shunts
what do areas of the lungs with greater ventilation act as
dead spaces
what makes up hemoglobin
4 iron molecules and 4 protein molecules
what is oxyhemoglobin
Hgb carrying O2
what is deoxyhemoglobin
Hgb that has released O2 to the peripheral tissues
Carbicyhemoglobin
Hgb bound to CO instead of CO2
what is the normal O2 carrying capacity in men and women?
13-16 in men
12-16 in women
what is the oxyhemoglobin dissociation curve
describes the relationship between SaO2 and the partial pressure of arterial O2
what are implications of a left shifted oxyhemoglobin curve
- increased O2 affinity
- reduced O2 delivery to tissues
what is a left shifted oxyhemoglobin curve caused by
- high pH (alkalosis)
- low temperature
- high O2 affinity
what are the implications of a right shifted oxyhemoglobin curve
- reduced O2 affinity
- increased O2 delivery to the tissues
what can a right shifted oxyhemoglobin curve be caused by
- low pH (acidic)
- increased O2
- High temperature
Areas of the Lungs: R. Anterior
1,3,4,5,8
areas of the lungs: L anterior
1,3,4,5,8
areas of the lungs: L posterior
1,2,6,9,10
areas of the lungs R posterior
1,2,6,8,9,10
