Bio260 Unit 2 Resource 9b. Cardiac Muscles (new method)

times on slide 38 not important, just know general process

Cardiac Muscle - Characteristic

1. cardiac muscles cells are _____

• striated

Cardiac Muscle - Characteristic

2. cardiac muscle cells have ____ located _____

   • larger than in skeletal muscle

• centrally, nuclei

Cardiac Muscle - Characteristic

3. Y-shaped ____: cells are _____

   • allows muscle fibers to ______ in more complicated arr w/i ______ to make an efficient _____ mechanism for emptying the heart

3. fibers, branched

   • interweave, fascicles, contraction

Cardiac Muscle - Characteristic

4. myofibrils are ____ dense and organized than those of skeletal muscle

5. alternate w/ abundant _______

   • may take up to 40% of _____ (abt 2% in skeletal)

   • heart relies almost exclusively on _____ respiration

4. less

5. mitochondria

   • cytoplasm

   • aerobic

Cardiac Muscle - Characteristic

6. intercalated discs: contact b/w cells is accomplished by ______ in the _______ region

7. T tubules are ______ and _____ numerous in cardiac muscles than skeletal muscles

8. cardiac muscle has _____ sarcoplasmic _____

6. interdigitation, transverse

7. larger, more

8. reduced, reticulum

Cardiac Muscle - Characteristics

9. cardiac muscles have _____ rather than _____

   • SR touches it in ____ rather than _____ length

10. cardiac muscle makes up the _____ of the heart

11. cardiac muscle is capable of generating ______ action potentials at ______ intervals

9. diads, triads

   • spots, whole

10. myocardium

11. endogenous, periodic

Cardiac Muscle - Characteristics

12. cardiac muscles can make a membrane potential that is ____ _____ nerve membrane potential

12. diff from

Cardiac Muscle - Characteristics

13. has cardiac cycle

• autorhythmic cell membranes show a _____ drift to threshold = ______ potential

• What is rest membrane potential at?

• slow, pacemaker

• -55

Pacemaker potential process

1) _____ depolarization/pacemaker potential

2) ______ ______

3) ______ potential

4) _____ _______

1. slow

2. rapid depolarization

3. action

4. rapid repolarization

Ionic basis of AP of Autorhythmic cells - Phase 1: Pacemaker potential

• _______ of voltage gated ____ channels (_____ ______) and voltage gated transient ______ channels

• _______ of voltage gated _____ channels

• opening, Na+, funny channels, Ca2+

• closure, K+

Ionic basis of AP of Autorhythmic cells - Phase 2: Rising Phase/Depolarization

• ______ of long-lasting voltage-gated _____ channels (______ Ca2+ channels)

• _____ influx of _____

• opening, Ca2+, L-type

• large, Ca2+

Ionic basis of AP of Autorhythmic cells - Phase 3: Falling Phase/Repolarization

• ______ of voltage gated ____ channels

• ______ of long lasting voltage gated _____ channels

• Potassium _____

• opening, K+

• closing, Ca2+

• efflux

Intrinsic cardiac conduction system

• made of ________ cardiac cells specialized to ____ and distribute ______ t/o the heart

• noncontractile, initiate, impulses

Sinoatrial/SA Node

• located in right ____ wall just inferior to ______ _____ _____ & generates 75 AP/min

• _______ (has sinus rhythm)

• no ______ elements, but connected directly to ____ fibers which makes it spread ____

• atrial, superior vena cava

• pacemaker

• contractile, atrial, faster

Propagation

• more ______ thru 3 specialized bundles of atrial muscle called _____ pathways

• nodal pathways have specialized ______ cells + ________

• rapid, internodal

• conductive, cardiomyocytes

Internodal Pathway

• ___ to ___ node

• Atria/Ventricles separate by ___-_____ fibrous tissue

• AV is only ______ connection

• AV nodal ____ is abt 0.1 sec

• net effect of transporting _____ impulse to ___ node w/i 30 msec; _____ of 130 msec in AV node and ____ system during which atria contract, filling the ______

• SA, AV

• non-conductive

• electrical

• delay

• conductive, AV, delay, bundle, ventricles

Interatrial pathway

• ___ → ___ atrium

• thru ____ junctions

• really ____

• right, left

• gap

• fast

Atrioventricular/AV node

• located in ____ part of ______ septum

• uses _______ pathway to spread _______

• upper, interarterial

• internodal, depolarization

Bundle of His

• AV bundle

• only _____ connection b/w atria/ventricles

• ____ & ____branch

• ______ abt 30 times per sec

• (nothing)

• electrical

• left, right

• depolarize

Purkinje fibers

• modified _____ fibers with few _____

• _____ 30 times per sec

• controls _____ and ______ muscles

  • ____ chordae tenineae

  • ____ tricuspid/mitral valve

• muscle, myofibrils

• depolarize

• ventricles, papillary

  • tighten

  • open

Control of heart rhythm

1) pacemaker (__ ____) generates wave of signals to _____

2) signals _____ getting to __ node

3) signals pass to ____ ____

4) signals spread thru-out ______

1. SA node, contract

2. delayed, AV

3. heart apex

4. ventricles

P-wave

depolarization of SA node → atria

QRS wave

ventricular depolarization/covers atrial repolarization

T-waves

ventricular repolarization

Cardiac Muscle Refractory Period

• ____

• period which heart _____ make AP

• _____ go into ____/_____

• long

• can’t

• can’t, tetany/summation

AP travels down T Tubules

• bulk of this req ____ for ______ which origin from the ______ ______ (SR)

  • ____-____ voltage gated _____ channels in T tubule _____

  • Ca2+ binds to _____ receptors

  • Ca2+ released from ___ thru ____ channel

  • Ca2+ is actively _____ _____ into __

• _____ & ____ antiport exchangers (NCX) make more minor contributions

• ca2+, contraction, sarcoplasmic reticulum

  • L-type, Ca2+, opens

  • Ryr

  • SR, Ryr

  • pumped back, SR

• Na+, Ca2+

Regulation of Stroke Volume

Regulated by: Preload, contractility, and afterload

Explain the process happening in this image

1. fluids flow from the SA node into the right and left atrium

   • it flows faster into the left atrium and slower into the right

2. the fluids then make contact with the AV node, travels quickly into the left and right ventricles, and spreads out