The Heart Flashcards
what is the sequence in the pulmonary circuit?
heart-> pulmonary arteries -> pulmonary capillaries -> pulmonary veins -> heart
What is special about the pulmonary arteries?
Arteries usually consist of oxygenated blood, however these arteries consists of deoxygenated blood
What is the sequence in the systemic circuit?
heart -> systemic arteries -> systemic capillaries -> systemic veins -> heart
Where is the apex in terms of the 4 chambers?
The apex is located in the let ventricle
What are the 2 parts of the pericardium and their relative location?
the fibrous pericardium and is superficial to the serous pericardium which is deep
What is the function of the fibrous pericardium?
protection, anchoring the heart to surrounding structures and prevents overfilling with blood
What is the fibrous skeleton of the heart?
dense connective tissue network that anchors cardiac muscle fibers, supports vessels and valves, and limits spread of action potentials
What separates the 2 atria?
interatrial septum
What separates the 2 ventricles?
interventricular septum
Which surface marker separates the atria from the ventricles both anteriorly and posteriorly?
coronary sulcus
Which 2 surface markings divide the 2 ventricles?
the anterior and posterior interventricular sulcus
What is the purpose of the atria?
they are the receiving chambers
How much activity do the atria contribute the pumping blood?
little
How many auricles are there and their purpose?
2: right and left
The purpose of the auricles are to aid the atria by slightly increasing the volume
What muscles are located in the wall of the right atrium and auricles?
pectinate muscles
Which marking is present in the fetus, but once born becomes a bone marking?
fossa ovalis
What is the function of the fossa ovalis n a fetus?
to pump blood between the right and left atria
What pumps blood into the right atrium? From where?
Superior vena cava: from above diaphragm
Inferior vena cava: from below diaphragm
Coronary sinus: from myocardium
Is blood in the right atrium deoxygenated or oxygenated?
deoxygenated
What pumps blood into the left atrium? From where?
the pulmonary veins, from the lungs
Is the blood in the left atrium deoxygenated or oxygenated?
oxygenated
What are the ventricles referred to as?
the discharging chambers
What connects the papillary muscles to valve cusps?
chordae tendiane
What is the function of the pulmonary trunk?
carry deoxygenated blood to the lungs
What is the function of the aorta?
carry oxygenated blood to the body
Which side is the pulmonary circuit pump?
right side
Which side is the systemic circuit pump?
left side
What causes the valves to open and close?
response to changes n pressure
What prevents backflow into the atria when the ventricles contract?
Atrioventricular (AV) valves
What are the 2 types of AV valves and their location?
tricupsid valve- right
bicuspid (mitral) valve- left
Which internal feature tightens, preventing valve flaps from everting into atria?
chordae tendinae
Which 2 valves prevent backflow into ventricles when ventricles relax?
Aortic and pulmonary semilunar valves
What supplies the arteries with blood?
right and left coronary arteries
What collects venous blood?
cardiac veins
How are adjacent cells joined in the cardiac muscle cell?
via intercalated discs
What are the 3 components that comprise the intercalated disc?
desmosomes and gap junctions
Of the 2 components of the intercalated disc which prevent cells from separting?
desmosomes
Of the 2 components which allow ions to pass from cell to cell?
gap junctions
True or False. Some cardiac muscles are not excitable.
False. Some are self excitable
True or False. Some cardiac muscle cells contract as a unit or not at all.
True
These have the ability to depolarize spontaneously and pace heart.
cardiac pacemaker cells
These are responsible for heart’s pumping activity.
contractile muscle fibers
What are the 3 stages in AP of contractile cardiac cells? Include what occurs at each stage.
- Depolarization. Na+ enters the cell
- Plateau phase- Ca2+ enters the cell
- Repolarization. K+ leaves the cell
What is angina pectoris?
severe chest pain due to ischemia. O2- deprives cells shift to anaerobic glycolysis causing lactic acid stimulates pain receptors
What occurs during myocardial infarction?
sudden death of myocardial cells resulting from prolonged coronary blockage
What initiates AP in the heart?
Pacemaker potentials
What are the 3 parts of the AP of pacemaker cells?
- Pacemaker potential
- Depolarization
- Repolarization
What occurs during pacemaker potential?
spontaneous depolarization that trigger AP once threshold is reached
What occurs during AP of Pacemaker cells?
Depolarization- Ca2+ channels open entering the cell
Repolarization: K+ leaves cell
What is the sequence of excitation of pacemaker cells?
- SA node -> AV node -> AV bundles -> Right and left branches -> Purkinje fibers
SA node
Located in the wall of the right atrium, initiates each heartbeat and determines heart rate
AV node
Inferior interatrial septum. Allows atria to finish contracting before ventricles contract
AV bundle
Superior Interventriclar septum. only electrical connection between atria and ventricles
Right and left bundle branches
run along interventricular septum and toward heart apex
Purkinje fibers
interventcular septum -> heart apex -> ventricular walls
What is an ECG/EKG?
Electrocardiogram. composite reading of all APs generated by pacemaker and contractile cells at a given time
What occurs at P wave? QRS complex? T wave?
P wave: atrial depolarization
QRS complex: ventricular depolarization
T wave: ventricular repolarization
When does atrial repolarization occur?
during QRS complex, specifically R wave
What causes a P wave?
atrial depolarization, initiated by SA node
What occurs after atrial depolarization?
the impulse is delayed at the AV node
What causes QRS complex?
ventricular depolarization begins at apex, atrial repolarization occurs
What causes the T wave?
ventricular repolarization begins at apex
What type of rhythm occurs when SA node is nonfunctional so the AV node is at 40-60 beats/min?
Junctional rhythm
What is called when the pacemaker is abnormal?
ectopic focus
What is the impaired transmission of impulses through AV node?
Heart block
Define ventricular fibrillation.
rapid, irregular contractions; heart cannot pump blood
When is lub heard?
when AV closes
When is dub heard?
when SL valves closes
What is indicated when there is a valve problem?
abnormal heart sound, heart murmur
Define systole and diastole.
Systole: period of contraction
Diastole: period of relaxation
What are the phases of the cardiac cycle?
- Ventricular filling
- Ventricular systole
a. Isovolumetric Contraction
b. Ventricular Ejection - Isovolumetric Relaxation
What is occurring at the beginning and ending of ventricular?
Beginning: AV open, SL valves close, blood flows passively into ventricles, ventricular pressure is low
Ending: Atria contract, ventricles have max amount of blood they will contain
What is occurring in Isovolumetric Contraction phase?
AV valves close, SL valves close, ventricles contract
What is occurring in Ventricular ejection?
AV valves are close, SL Valves open, ventricular pressure has increased,, blood expelled from heart
What is occurring in Isovolumetric Relaxation
Ventricles relax, SL vales close when pressure in ventricles are less than pressure in aorta and pulmonary trunk
How do you calculate cardiac cycle length?
60 sec/# beats
What is Cardiac output?
amount of blood pumped out by each ventricle in 1 minute HRxSV
What is SV?
volume of blood pumped out by a ventricle with each beat
What is the normal CO?
5.25L/min
Difference between maximum and resting CO
Cardia reserve
What is the typical for nonathletic and world-class athletes?
Non: 4-5 times
Athletes: 7x
EDV
End diastolic volume. Volume of blood in each ventricle at the end of ventricular diastole
ESV
End Systolic Volume. Volume of blood remaining in each ventricle after it has contracted
What is the equation for SV?
EDV-ESV
What are three main factors that affect SV?
Preload, Contractility, and afterload
Preload
degree to which cardiac muscle cells are stretched before they contract; increase EDV
Frank-Sterling law of heart
SV increases in response to an increase in EDV
Contractility
contractile strength achieved at a given preload, increase ESV
Afterload
pressure in aorta and pulmonary trunk, decrease in ESV
What factors influence HR?
ANS, chemicals, age, gender, and exercise
What type of innervation speeds up depolarization of SA node and release NE?
Sympathetic innervation
What type innervation hyperpolarizes SA node and causes the vagus to release ACh?
Parasympathetic innervation
Tachycardia
100 beats/min rapid heart beat
Bradycardia
60 beats/min slow heart beat
What causes congestive heart failure?
Failure of either ventricle to eject blood effectively
If the left side causes congestive heart failure, what are the results?
Left side does not adequately eject returning blood, causing pulmonary edema
If the right side causes congestive heart failure, what are the results?
blood backs up into the vena cava and fluid leaks into issue spaces causing peripheral edema
In a fetus, why is little blood send through pulmonary circuit?
lungs are not yet functional
What are 2 structures in a fetus that allow blood to bypass pulmonary circuit?
foramen ovale( left and right atria) and ductus arteriosus (pulomnary trunk to aorta)
When baby takes first breath what happens to the ductus arteriosus?
it constricts and forms the ligamentum arteriosum
