Solved Part B. The Cardiac Cycle Phases of the cardiac cycle ... - Free Printable

Let’s solve this step by step.

We are given 5 phases of the cardiac cycle:
- Late diastole
- Atrial systole
- Isovolumetric ventricular contraction
- Ventricular ejection
- Isovolumetric ventricular relaxation

And we have 5 figures labeled A, B, C, D, E — with Phase 1 already matched to Figure C.

We need to match each phase to the correct figure (A–E), then fill in the table for:
- Atrial state (relaxed/contracting)
- Ventricular state (relaxed/contracting)
- AV valves (open/closed)
- Semilunar valves (open/closed)

Also, later we’ll add “1st heart sound” and “2nd heart sound” where appropriate.

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Step 1: Understand what happens in each phase

#### 1. Late Diastole
- Heart is mostly relaxed.
- Blood flows passively from atria → ventricles through open AV valves.
- Semilunar valves are closed.
- Atria may be filling or just finishing filling; ventricles are filling too.
→ This should show both chambers relatively full, AV valves open, semilunar closed.

Looking at figures:
- Figure E shows blue (deoxygenated blood) entering right side, red (oxygenated) on left — looks like passive filling? But let’s compare all.

Actually, let’s go phase by phase and match logically.

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Step 2: Match phases to figures

We know Phase 1 = Figure C (given).

Look at Figure C:
- Both atria and ventricles appear filled.
- AV valves seem open (blood can flow down).
- Semilunar valves closed.
→ This matches Late Diastole — passive filling before atrial kick.

So:
> Phase 1: Late diastole → Figure C

Now next:

#### Phase 2: Atrial Systole
- Atria contract to push last bit of blood into ventricles.
- Ventricles still relaxed.
- AV valves OPEN (to allow blood in).
- Semilunar valves CLOSED.
→ So atria contracting, ventricles relaxed, AV open, SL closed.

Which figure shows that?

Figure A: Looks like atria are squeezing (smaller?), ventricles bigger? Maybe.

Wait — better to think visually:

In standard diagrams:
- When atria contract, they shrink slightly, pushing blood down.
- Ventricles are still relaxed and receiving blood.

Figure A: Right atrium looks contracted? Left too? And ventricles look fuller than before? Possibly.

But let’s check others.

Figure B: Looks like ventricles are contracting — walls thickened, maybe ejecting? That might be later.

Figure D: Ventricles look very full, possibly starting to contract? Or after ejection?

Figure E: Looks like early filling — maybe late diastole? But we already assigned C to late diastole.

Wait — perhaps Figure E is actually late diastole, and C is something else? But problem says Phase 1 = C.

Let me reassign based on logic.

Standard order of cardiac cycle:

1. Late Diastole – passive filling, AV open, SL closed → Figure C (as given)
2. Atrial Systole – atria contract, push extra blood into ventricles → AV still open, SL closed → which figure? Probably Figure A — because it looks like atria are actively pushing (maybe darker color or shape change?). Actually, looking again:

Figure A: Blue area (right heart) — atrium looks smaller, ventricle larger → suggests atrial contraction pushing blood down.

Yes → Phase 2: Atrial systole → Figure A

3. Isovolumetric Ventricular Contraction
- Ventricles start contracting → pressure rises → AV valves snap shut (because pressure in ventricles > atria)
- But not enough pressure yet to open semilunar valves → so ALL valves closed!
- Volume doesn’t change (“isovolumetric”)
→ So: atria relaxed, ventricles contracting, AV closed, SL closed.

Which figure shows that?

Figure B: Looks like ventricles are contracting (walls thickened), no blood flowing out yet? AV valves probably closed (no arrow showing inflow), semilunar also closed.

Yes → Phase 3: Isovolumetric ventricular contraction → Figure B

4. Ventricular Ejection
- Ventricles continue contracting → pressure exceeds arterial pressure → semilunar valves OPEN
- Blood ejected into arteries
- AV valves remain closed
→ Atria relaxed, ventricles contracting, AV closed, SL open

Which figure?

Figure D: Looks like blood is being pushed out — arrows going up into arteries? Yes! In Figure D, you can see red and blue streams going upward — that’s ejection.

→ Phase 4: Ventricular ejection → Figure D

5. Isovolumetric Ventricular Relaxation
- Ventricles relax → pressure drops → semilunar valves close (when ventricular pressure < arterial)
- But AV valves haven’t opened yet (ventricular pressure still > atrial)
→ All valves closed again!
- Atria are relaxing/filling, ventricles relaxing but not yet filling

Which figure?

Figure E: Looks like everything is quiet — no active pumping, valves likely closed. Atria might be filling slowly, ventricles emptying? Wait — actually, in isovolumetric relaxation, ventricles are relaxing but volume constant until AV opens.

Figure E shows minimal activity — probably this one.

Also, note: After ejection (D), the next phase is relaxation with all valves closed → Figure E fits.

→ Phase 5: Isovolumetric ventricular relaxation → Figure E

Perfect.

So summary:

| Phase | Name | Figure |
|-------|-------------------------------|--------|
| 1 | Late diastole | C |
| 2 | Atrial systole | A |
| 3 | Isovolumetric ventricular contraction | B |
| 4 | Ventricular ejection | D |
| 5 | Isovolumetric ventricular relaxation | E |

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Step 3: Fill in the table

For each phase, determine:

- Atrial state: relaxed or contracting?
- Ventricular state: relaxed or contracting?
- AV valves: open or closed?
- Semilunar valves: open or closed?

Let’s go row by row.

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#### Row 1: Late diastole (Figure C)

- Atria: relaxed (they’re just sitting there, letting blood flow in passively)
- Ventricles: relaxed (filling passively)
- AV valves: OPEN (allowing blood from atria to ventricles)
- Semilunar valves: CLOSED (not ejecting yet)

✔

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#### Row 2: Atrial systole (Figure A)

- Atria: CONTRACTING (pushing blood into ventricles)
- Ventricles: relaxed (still receiving blood)
- AV valves: OPEN (must be open to let blood in)
- Semilunar valves: CLOSED (not ready to eject)

✔

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#### Row 3: Isovolumetric ventricular contraction (Figure B)

- Atria: relaxed (done contracting, now refilling)
- Ventricles: CONTRACTING (starting to squeeze)
- AV valves: CLOSED (snapped shut when ventricular pressure rose)
- Semilunar valves: CLOSED (pressure not high enough yet to open them)

✔

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#### Row 4: Ventricular ejection (Figure D)

- Atria: relaxed
- Ventricles: CONTRACTING (ejecting blood)
- AV valves: CLOSED (keep blood from going back to atria)
- Semilunar valves: OPEN (letting blood out to arteries)

✔

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#### Row 5: Isovolumetric ventricular relaxation (Figure E)

- Atria: relaxed (may be starting to fill again)
- Ventricles: RELAXING (but not yet filling — waiting for AV to open)
- AV valves: CLOSED (ventricular pressure still higher than atrial)
- Semilunar valves: CLOSED (just snapped shut as ventricles relaxed)

✔

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Step 4: Add heart sounds

Heart sounds occur due to valve closures.

- 1st heart sound (S1): Caused by closure of AV valves → occurs at START of ventricular systole → i.e., at beginning of isovolumetric ventricular contraction

→ So add "1st heart sound" in row 3 (isovolumetric ventricular contraction)

- 2nd heart sound (S2): Caused by closure of semilunar valves → occurs at END of ventricular systole → i.e., at start of isovolumetric ventricular relaxation

→ So add "2nd heart sound" in row 5 (isovolumetric ventricular relaxation)

Note: Some sources say S2 occurs during early relaxation — yes, exactly when semilunar valves close.

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Final Table Construction

We'll write the completed table below.

Remember: The question asks to complete the table using Figure 2 and the listed phases.

Also, Part 7 says to add the heart sounds to appropriate cells — so we’ll include them in the same rows.

Since the original table has columns:

- Phase of the cardiac cycle
- Figure (A,B,C,D,E)
- Atrial state
- Ventricular state
- State of AV valves
- State of semilunar valves

And then separately, we add heart sounds — probably in a new column or noted in the cell. Since instruction says “add to appropriate cells”, I’ll assume we can note them under the phase or in a separate note — but since it's a table, perhaps we add a seventh column? But original only has six.

Looking back at user image description — it says:

> 7. Add the following to the appropriate cells in the table:
> [1st heart sound] [2nd heart sound]

Probably means: in the row where it occurs, write it somewhere — maybe under “Phase” or create a note. Since it’s ambiguous, safest is to mention it in the explanation and indicate which row.

But for final answer, since it’s a table, I’ll present the main table first, then specify where to add heart sounds.

Alternatively, perhaps the table expects us to include heart sounds in the “Phase” column or as an additional label.

Given typical textbook format, often heart sounds are added as notes in the corresponding phase row.

I’ll structure the final answer as a completed table with 6 columns, and then state clearly where to place the heart sounds.

But wait — looking again at the original task layout:

The table has 6 columns as listed. Then part 7 says “add to appropriate cells” — meaning within those existing cells? Unlikely. More likely, we are to insert the heart sound labels into the table — perhaps in a new row or as annotations.

To avoid confusion, I’ll provide the fully filled table with 6 columns, and then explicitly say:

> In the row for “Isovolumetric ventricular contraction”, add “1st heart sound”
> In the row for “Isovolumetric ventricular relaxation”, add “2nd heart sound”

That should satisfy the requirement.

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✔ Final Answer:

Completed Table:

| Phase of the cardiac cycle | Figure | Atrial state | Ventricular state | State of AV valves | State of semilunar valves |
|----------------------------------------|--------|----------------|-------------------|--------------------|---------------------------|
| Late diastole | C | relaxed | relaxed | open | closed |
| Atrial systole | A | contracting | relaxed | open | closed |
| Isovolumetric ventricular contraction | B | relaxed | contracting | closed | closed |
| Ventricular ejection | D | relaxed | contracting | closed | open |
| Isovolumetric ventricular relaxation | E | relaxed | relaxed | closed | closed |

Add these to the appropriate cells:

- In the row for Isovolumetric ventricular contraction, add: 1st heart sound
- In the row for Isovolumetric ventricular relaxation, add: 2nd heart sound

*(Note: Depending on how your teacher wants it formatted, you could write the heart sound inside the “Phase” cell or in a new column — but since instructions don’t specify, placing it as a note in the correct row is acceptable.)*