Flashcards in Heart Deck (51):
What is the purpose of the fibrous layer of the pericardium?
Prevents overstretching of the heart
What is the serous layer of the pericardium?
What does the endothelium do?
Covers the valves of the heart
The right atrium receives blood from which three major veins?
Inferior vena cava, superior vena cava, coronary sinus
Which valve does the right ventricle have?
Pulmonary semilunar valve
The left atrium receives blood from what?
Bicuspid valve is in which atrium?
Where are the aortic semi-lunar valves located?
Aortic semi-lunar valve
What happens to blood in the left ventricle?
Oxygenated blood is ejected into the system circulation
What happens when the atrioventricular valves open?
Blood moves into ventricles, papillary muscles are relaxed while chordae tendinae is slack
Left AV valve = ______________ valve. Right AV valve = ______________ valve.
Left AV is bicuspid, right AV is tricuspid
What happens when the ventricles contract?
Pressure drives the cusps upward, papillary muscles contract, chordae tendinae tightened and prevents the cusps from opening into the atrium.
What do the semi-lunar valves do?
Allow ejection of blood into vessels and prevent backflow into the ventricles.
When are the semilunar valves open?
When ventricular pressure exceeds arterial pressure.
The entire body receives blood from the systemic circulation except which organ? Why?
Lungs, because they are supplied by pulmonary circulation.
Where do the coronary arteries originate?
At the base of the ascending aorta
What does the left coronary artery supply?
Both ventricles and the left atrium
What does the right coronary artery supply?
Supplies both ventricles
Which veins enter the coronary sinus?
Great cardiac vein, middle cardiac vein, posterior vein of left ventricle, oblique vein of left atrium. AND SMALL MAY ENTER…..
What are the three phases of the cardiac cycle?
Relaxation, ventricular filling, ventricular systole.
Difference between systole and diastole?
Systole – phase of contraction, Diastole – phase of relaxation
Explain the relaxation period.
When ventricles relax, all 4 chambers are in diastole. Blood flows back to the ventricles closing the semilunar valves. Pressure falls in the ventricles and AV valves open to initiate ventricular filling.
During ventricular filling, AV valves are (open/closed), and semi-lunar are (open/closed).
AV valves are open, semilunar are closed
_____% of ventricular filling occurs without atrial systole. _____% occurs with contraction of the pectinate muscle.
Explain ventricular systole.
Ventricular contraction pushes blood up against AV valves (forcing them shut). Pressure inside ventricles rises. Semi lunar valves open, blood is ejected into the pulmonary and systemic circulation. Stops when ventricles relax and then cycle restarts.
When do the semi-lunar valves open?
When pressure of ventricles exceeds that in the arteries(??)
What is “lubb”?
Closing of AV valves, beginning of ventricular systole.
What is “dupp”?
Closing of semilunar valves, end of ventricular systole.
What is S1?
What is S3 and S4?
S3 – rapid ventricular filling, S4 – atrial systole.
Which 2 systems is the heart influenced by in its movement?
Vagus nerve and ANS AND specialized muscle tissue within the heart
What do the vagus nerve and ANS do?
Regulate the speed of the contraction (inhibit)
What does the specialized muscle tissue within the heart do?
Initiates contractions, aka cardiac cycle (SA Node)
Where is the SA node located?
Wall of the R. atrium
Explain the path of the conduction of the heart (steps).
SA Node > spread over both atria > delay (so that atria and ventricles don't contract at the same time) > impulse conducted through AV bundle > travel through interventricular septum > Apex > Purkinje fibers > contract ventricle
What is the AV node supplied by?
How do the lungs get blood?
Deoxygenated blood from the right ventricle goes to the air sacs within the lungs (alveoli), then CO2 passes into alveoli (exhaled), inhaled O2 from air into blood, pulmonary veins transport oxygenated blood to the left atrium and then ejected into systemic circulation via left ventricle.
What forms in infants related to their circulation?
Formation of septum primum and septum secundum.
What closes in infants related to their circulation?
Closure of the foramen ovale, because it becomes the fossa ovalis. Closure of the ductus venosus and ductus arteriosus.
When does the foramen ovale close?
Closure at birth or after several weeks (or not at all!)
When does the ductus venosus close?
After birth up until 2-3 months
What does the ductus venosus become?
When does the ductus arteriosus close?
At birth up until 3 months.
What does the ductus arteriosus become?
When do the umbilical arteries close?
Closes a few minutes after birth
What do the umbilical artieries become?
MEDIAL umbilical ligaments
What does the umbilical vein close?
A few minutes after birth.
What does the umbilical vein become?
What DOES NOT function until after birth?
Lungs, kidneys, GI
How does the fetus obtain O2 and nutrients?
From maternal blood