The end Flashcards Preview

B2 > The end > Flashcards

Flashcards in The end Deck (192)
Loading flashcards...

What is happening to the ventricles, atria, valves and on EKG strip during the first heart sound (S1)?

AV valves close because ventricular pressure exceeds atrial pressure.
Isovolumic contraction occurs due to rapid increase in ventricular pressure.
Occurs during QRS complex


What is happening to the ventricles, atria, valves and EKG strip during the second heart sound (S2)?

Ventricular depolarization (T wave), closing of semi-lunar valves [due to ventricular pressure falling below aortic], isovolumic relaxation, ventricular pressure declines until exceeded by atrial P


What happens during the ventricular filling phase to the atria, valves, and on EKG strip?

AV valves are open, aorta and pulmonic valves are closed, atrial contraction, P wave


What happens during the ventricular ejection phase to the atria, valves, and on EKG strip?

AV valves closed, aorta and pulmonary valves open, ventricular pressure rises suddenly and then declines once rate of evacuation of blood is greater than rate of ejection.
Towards end marks beginning of T wave.


What produces the S3 sound?

ventricular filling - seen in young and some pathologies


What produces the S4 sound?

atrial contraction get last bit of blood out


________ have ATPase activity and ______ are made up of monomer G-actin

thick filaments, thin filaments


Regulatory proteins are tightly bound to ______ on ____ filaments and are responsible for coupling of intracellular Ca++ transient to acto-myosin bridge cycling

actin, on thin filaments


Tropomyosin are two non-identical chains that lie in one of 2 groove formed by 2 actin polypeptide chains. What is their function?

allow or prevent interaction of actin and myosin


What three proteins make up the troponin complex and what is their function?

1) Troponin C = bind Ca++; contain 4 binding sites, I and II are specific for Ca++ and II and III bind both Ca++ and Mg++ and stablizing the troponin complex
2) Troponin I = inhibits interaction between actin and myosin [weaker than tropomyosin]
3) Troponin T = maintains the troponin complex by binding the other two


What enhances troponin I activity?

PKA phosphorylation --> inhibits cross-bridge cycling during diastole


PKA modulates EC coupling by phosphorylating 4 main target proteins? How?
How is PKA activated?

Ca++ channels, Ryr in SR, phospholamban (PLB), troponin

1) Ca++ channels = enhance open probability
2) Ryr in SR = stimulates Ca++ influx to increase Ryr channel activity which improves Ca++ release
3) Phospholamban(PLB) = normally represses activity of Ca++ ATPase pump and inhibits relaxation of Ca++ transient; once phosphorylated, repression removed.
4) Reduces affinity of troponin complex for Ca++ --> relaxation

PKA is activated by sympathetic stimulation by NE


The _____ of the sarcomere is the space where actin is absent

H zone


The sarcomere is the area between each ____ and poses a physical constraint on max myofibril shortening

Z line


The I band are thin, light areas that contain ______ and ______

Z lines, actin filaments


The ________ are opaque, dark areas consisting of ordered overlap between thick filaments, mainly ______

A bands, myosin

[also contain actin]


Describe what happens during sarcomere contraction

During contraction, actin and myosin filaments interact and actins are pulled toward center of each myosin myofilament.. The H zones disappear and the I band becomes very narrow.


Describe parasympathetic effect on heart rate and conduction velocity

Ach binds muscarinic receptors on the SA node, atria and AV node -->
- decrease heart rate (via dec in rate of phase 4 depol via dec If)
- decreased conduction velocity through AV node --> inc PR interval (dec inward ca++ current)


Describe sympathetic effect on heart rate and conduction velocity

- Norepinephrine acts on beta receptors.
- Increased HR by inc rate of phase 4 depol (inc If)
- Inc conduction velocity through AV node, dec PR interval (inc inward Ca++ current)


True/False: In an EKG, the signal travels from positive to negative leads

FALSE - negative to positive


Describe the arrangement of bipolar lead I

Left arm + and right arm negative [0]


Describe the arrangement of bipolar lead II

left foot + and right arm - [60]


Describe the arrangement of bipolar lead III

left foot + left arm - [120]


Describe the arrangement of avF

left foot positive, right and left arms have indiff electrode [90]


Describe the arrangement of avL

left arm +, indiff electrode by right arm and left foot [330]


Describe the arrangement of avR

right arm +, indiff electrodes on left foot and eft arm [210]


Describe the location and attachments to fibrous skeleton of the heart

- in the coronary sulcus
- all muscles and ventricles sweep up in a circular or oblique fashion and attach to the fibrous skeleton
- All valves of the heart are embedded in the same plane of fibrous skeleton
- The fibrous skeleton provides for attachment of the cardiac muscle fibers of atria and ventricles and acts as an insulator
- penetrated by AV bundle that is the only connecting link between atrial and ventricular muscle


Pain sensations from the heart are carried on _______ fibers whose cell bodies are found in the ______

sympathetic, dorsal root ganglia


The inferior vena cava is derived from the ______

right vitelline vein


The superior vena cava is derived from the _______

right anterior cardinal vein