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25 Cards in this Set

  • Front
  • Back
Diff between pulmonary and system circuits.

What do vessels do? Describe 3 types
To and from lungs

to and from rest of body

Carry blood through circuits,
blood away from heart
to heart
permit exchange
Compare musculature between ventricles
Left has more and its walls are thicker
Which side of the heart is more muscular and why?
Left, pumps blood with greater pressure
Function of chordae tendineae?
Prevents backflow into left atrium
Blood coming from lungs goes through which valve first?
Semi-lunar (pulmonary and aortic) valves do what?
Prevent blood from flowing from aorta dn pulmonary artery back into atria
Role of connective tissues and fibrous skeleton in heart?
physical support, elasticity, distribute force of contraction, prevent overexpansion

Fibrous skel:
stabilizes valves, isolates atrial and ventricular cells
Role of intercalated discs, and gap junctions?
Where does calcium enter from?
Physcial coupling, electrical coupling

ECF and SR
What are the two classes of cardiac muscle cells? Give examples
Muscle cells of Conducting system (modified cardiac muscle cells): internodal PW cells, AV bundle, bundle branches, purkinje fibers

Contractile cells
Describe path of electrical signal in a heart beat

On an ECG, where is a good spot to look for where electrical signal originates?Where atria contracts? Ventricles contract?
SA Node-->internodal PWs (small delay)-->AV node-->AV bundle-->Bundle branches-->Purkinje fiber

Right before the hill starts going up

small round lump before spike
What is depolarization of the heart due to?
Slow influx of Na+ ions
Describe ionic paths in skeletal and cardiac APs? How do the two APs compare?
Rapid depol by entry of Na+ (Na+ ch. open)
Na+ ch close, Ca++ open

Ca++ enters
Ca++ closed, K+ open

K+ loss

Cardiac much loooonger action potential and contraction
What is cardiac output? How is it calculated?
Amoutn of blood pumped by each ventricle in one minute

HRate (beats/min) x Stroke volume (ml/beat)
Describe how stroke volume changes during different phases of contraction.
Medium-high at Ventricular diastole, highest at end-diastloic volume, lower at ventricular systole, lowest at end-systolic volume
Describe factors affecting heart rate
Autonomic innervation: cardiac reflexes, tone, SA node

Hormones, Epi, norepi, thyroid hormone

venous return
Heart rate describes what?
End-diastolic volume?
End-systolic volume?
Stroke voluime?
How fast
Fill volume
Empty volume
How much
What does the cardiac reflex detect?
blood pressure, dissolved gas concentrations
How does norepi increase heart rate?
increases rate of depol
What is the role of the SA node? How is it modified? Give examples.
Establish baseline

ANS: atrial reflex, stretch
Parasymp stimuln: hyperpolarizes so slower depolarization and lower heart rate

Symp stimuln: deduced repolarization, more rapid depol
What would stretching of the atria indicate? Hear response? How?
increased blood return to heart, beat faster, increased symp activity, increased depol of atrial cells
What does the Farnk-Starling principle state?
What are factors affecting end systolic volume? Describe them
More in-more out

Preload: more blood in-->more stretch-->more force

Contractility: how much force?

Afterload: resistance to emptying heart
What is end diastolic volume?
Fill volume
What does inotropic mean?
Effect of symp stimln on it? How?

Para stimln? How?
Contractility of muscle tissue

Positive, release NE (more force, more pumped blood)

Negative, ACh, less blood pumped
Effect of exercise on cardiac output?
What is cardiac reserve?
Diff between resting and maximal cardiac output