Phys 3 Exam 1

What type of circulation is involved with the right side of the heart?

Pulmonary circulation

What does pulmonary circulation do?

1. Pump deoxygenated blood from heart to the lungs for gas exchange

2. Pumps oxygenated blood from the lungs back to heart

What type of circulation does the left side of the heart use?

Systemic circulation

What is systemic circulation?

1. Pumps oxygenated blood from the heart to the tissues of the body and gas exchange

2. Pumps deoxygenated blood back to heart

The structures of the pulmonary circuit include___

1. Right atrium

2. tricuspid valve

3. right ventricle

4. pulmonary valve

5. pulmonary trunk

6. R/L pulmonary arteries

7. Lungs

8. R/L pulmonary veins

The key structures of systemic circuit are___

1. left atrium

2. mitral valve

3. left ventricle

4. aortic valve

5. body

6. superior/inferior vena cava

What is the order from outside to inside of the pericardium?

1. FIbrous pericardium

2. Parietal layer of serous pericardium

3. Space

4. Epicardium (visceral layer of serous pericardium)

What is the function of the pericardium?

allows for beat without friction, provides room for heart expansion and resist excessive expansion

What are the three layers of the heart wall?

1. Epicardium

2. Myocardium

3. Endocardium

What layer of heart wall are the coronary blood vessels present?

Epicardium

What motion does the myocardium use for contraction?

wringing like motion

What does the atrioventricular sinus separate?

atria and ventricles

What does the interventricular sulcus separate?

divides the right ventricle from the left

contains coronary blood vessels

What does interatrial septum seperate?

the atria

What are pectinate muscles?

internal ridges of myocardium in right atrium and both auricles

RIGHT ATRIUM ONLY

What does interventricular septum seperate?

separates ventricles

What are trabeculae carneae?

internal ridges in both ventricles

What are the two functions of trabeculae carneae?

1. Prevent ventricle walls from sticking together after contraction

2. contraction pulls on chordae tendineae (preventing prolapse of the mitral and tricuspid valves)

What is the moderator band?

reinforces the thin wall of the right ventricle

What are AV valves function?

control blood flow between atria and ventricles

What is special about chordae tendineae?

prevent AV valves from flipping or bulging into atria when ventricles contract

What do semilunar valves control?

control flow into great arteries, open and close because of blood flow and pressure

What are the two semilunar valves?

1. Pulmonary valve: opening between right ventricle and pulmonary trunk

2. Aortic valve: opening between left ventricle and aorta

What occurs when ventricles are in a relaxed state?

Ventricular volume is increased

pressure is decreased

blood volume is decresed

What happens when ventricles contract?

Ventricular volume is decresed

Blood pressure is increased

Blood volume is increased

Flow through coronary arteries is greatest when___

heart relaxes

T/F contraction of the myocardium compresses the coronary arteries and obstructs blood flow

True

What supplies the left ventricle and left atrium?

Circumflex branch off left coronary artery

What supplies left atrium, left ventricle, interventricular septum, AV bundles?

Left coronary artery branches off the ascending aorta

What supplies blood to both ventricles and anterior two thirds of the interventricular septum?

Anterior interventricular branch/Left anterior descending artery off LCA

What supplies right atrium and sinoatrial node, AV node, posterior part of interventricular septum?

Right coronary artery

What supplies lateral aspect of right atrium and ventricle?

Right marginal branch off RCA

What supplies posterior walls of ventricles and posterior 1/3 of interventricular septum?

Posterior interventricular branch off RCA

What is coronary artery disease?

constriction of the coronary arteries

What causes CAD?

begins when endothelium damaged by hypertension, diabetes, smoking, or other causes

What can CAD cause?

Angina pectoris- intermittent chest pain, by obstruction 75% of the blood flow

causes coronary artery spasms due to lack of secretion of nitric oxide

What is a major risk factor for CAD?

1. excess LDL in blood with defective LDL receptors in arterial walls

   examples of preventable risk factors- obesity and smoking

What is treatment for CAD?

coronary bypass surgery

balloon or laser angioplasty

insertion of a stent to prevent narrowing

What is angina pectoris?

chest pain form partial obstruction of coronary blood flow

What is myocardial infarction?

sudden death of a patch of myocardium resulting from long-term obstruction of coronary circulation

T/F Most coronary blood returns to right atrium by way of the coronary sinus

True

What three inputs drain into coronary sinus?

1. Great cardiac vein

2. Posterior interventricular vein

3. Left marginal vein

What three inputs drain into great cardiac vein?

1. Posterior cardiac vein

2. Middle cardiac vein

3. Small cardiac vein

What does the chordae tendineae connect?

AV valves to papillary muscles

T/F Papillary muscles coordinate timing of electrical conduction

True

What is the most common valve be replaced?

aortic valve

What valve is the most common valve to be repaired?

mitral valve

What are the three ways deoxygenated blood enters the heart? (TQ)

1. Inferior vena cava

2. Superior vena cava

3. Coronary sinus

What is the flow of blood? (TQ)

1. Inf VC/Sup VC/ Coronary sinus

2. Right atrium

3. tricuspid valve

4. right ventricle

5. pulmonary valve

6. pulmonary trunk

7. R/L pulmonary arteries

8. lungs

9. R/L pulmonary veins

10. left atrium

11. mitral valve

12. left ventricle

13. aortic valve

14. aorta

15. body

or from aortic valve back to heart

What makes up 99% of cells in the atria and ventricles?

Myocardial contractile cells

What are the structures of the cardiac muscle? (TQ)

1. Intercalated discs- join cardiomyocytes end to end and have three structures:

1. Interdigitating folds

2. Mechanical junction

3. Electrical junction (GAP junctions)

What is the function of interdigitating folds?

increases surface area

What is the function of mechanical juctions?

adheres cells together

What is the function of electrical junction?

protein channels that allow ions to flow between cells

Cardiac muscle depends almost exclusively on ___ ___ to make ATP

aerobic respiration- FATIGUE RESISTANT

rich in myoglobin, glycogen and mitochondria

What is the major fuel source used by cardiac muscle?

Fatty acids (60%)

glucose, ketones, lactate and amino acids

T/F Cardiac muscle is more vulnerable to oxygen deficiency than lack of a specific fuel

True

What is the conduction system made of?

internal pacemaker and “nerve like” conduction pathways through the myocardium to generate a heart beat

What order does the conduction system generates a rhythmic electrical signals in what order?

1. SA node (pacemaker)

2. AV node

3. AV bundle (bundle of his)→R/L bundle branches

4. Purkinje fibers

What is the flow of electrical impulses during conduction system?

1. SA (pacemaker) nodes fires (initiates heart beat and determines HR)

   Located in the right atrium near base of superior vena cava

2. Electrical impulses spread to left atrium and AV node

3. AV node fires (electrical gateway to the ventricles)-slows down the signal so the ventricles can fill

4. Excitation spreads down AV (Bundle of HIS)-divides into L/R bundle branches and branches pass through interventricular septum

5. Purkinje fibers distribute excitation through ventricular myocardium

What effect do the sympathetics play in control of heart rate?

• increases heart rate

• originates in lower cervical and upper thoracic segments

• Fibers terminate in the SA and AV nodes, atrial, ventricular myocardium, aorta, pulmonary trunk, and coronary artery

What role do parasympathetics play in control of heart rate?

• slows heart rate

• originates in nuclei of the vagus nerves

• fibers from right vagus nerve lead to the SA node

• fibers from the left vagus nerve lead to the AV node

• little/no stimulation of the myocardium

Explain the SA node action potential

1. Phase 4: starts at -60mV and drifts upward due to slow Na+ inflow via HCN channels (funny currents)- pacemaker potential

2. Around -50mV transient (T-type) Ca2+ channels open= further depolarization

3. when threshold of -40 mV is reached, L-type Ca2+ and Na+ open→faster depol occurs peaking at 0 mV (phase 0)

4. Phase 3: K+ channels open and potassium leaves cell→ causing repolarization and L-type channels inactivated and close

5. Once K+ channels close, pacemaker potential starts over

What causes cardiomyocyte action potential?

SA node impulse hits

What are the steps of cardiomyocyte action potential?

1. (Phase 0)- stimulus opens Na+ gates, membrane depolarizes rapidly→ Action potential peaks at +30 mV

2. (Phase 1)- transient outward flow of K+= early repolarization of cells

3. (Phase 2)- plateau→ Ca+ in to K+ out is equal

4. (Phase 3)- Ca+ channels close, K+ open→ has a long absolute refractory period (prevents tetanus)

5. (Phase 4)- resting phase- only K+ channels are still open, establishes RMP (-90mV)

What is junctional/ nodal rhythm?

abnormal heart rhythm that originates from AV node or His bundle

HR is set by AV node (40-50 bpm)

What are the ranges of abnormal heart rate?

> 100 bpm= tachycardia

<50 bpm= bradycardia

What occurs in the P wave?

1. SA node fires

2. Atria depolarize and contract

3. Atrial systole begins 100 ms after SA signal

What happens during the QRS phase?

1. Ventricular depolarization

2. Atrial repolarization often is buried in the QRS complex

What occurs in the ST segment?

Ventricular systole (cx)

What occurs in the T wave?

Ventricular repolarization and relaxation

What is arrhythmia?

any abnormal cardiac rhythm

What are the causes of arrhythmia?

1. abnormalities in conduction pathways

2. electrolyte and hormone imbalances

   May lead to:

   1. Myocardial infarction

   2. Heart enlargement

What is ventricular fibrillation?

electrical signals traveling randomly to the myocardium

ventricles contract rapidly and in an uncoordinated manner

hallmark of MI

What is atrial fibrillation?

uncoordinated contraction of atria (irregular)

atria and ventricles don’t work together= poor pumping

Increased risk for MI, stroke, blood clots

What are A Fib causes?

1. tobacco

2. High blood pressure

3. obesity

4. diabetes

What are some complication of A-fib?

1. Stroke

2. MI

3. Heart failure

4. Systemic embolism

What are heart blocks?

delayed transmission of electrical signals through the AV node

What are heart blocks due to?

1. Disease

2. Degeneration

What is a first degree AV block?

electrical signals are slowed as they pass form the SA node to the AV node→ will eventually reach the ventricles

What is a second degree AV block Type 1?

electrical signals are delayed with each heartbeat until a beat is dropped completely

prolongation of PR interval followed by a P wave with no QRS complex

What is a second degree AV block type 2?

electrical signals do not reach the ventricles

non-conducted P wave with a dropped QRS complex

What is a third degree AV block/complete heart block?

atria and ventricles are depolarizing independently because none of the signal reaches the ventricles

regular P wave and a regular but unusually slow QRS pattern

What two main variables govern fluid movement?

1. Pressure causes flow and resistance opposes it

2. Fluid will only flow if there is a pressure gradient ( pressure difference)

   Fluid flows from high→low pressure

   F= change P/R

T/F opening and closing of valves are governed by the changes in pressure

True

When the ventricles are in diastole, what is the pressure and volume?

ventricular volume is high

pressure is low

AV VALVES AND SEMILUNAR VALVES ARE CLOSED

T/F when the volume in the aorta and pulmonary trunk is low, the pressure will also be low

FALSE- Pressure is high

when ventricles begin to contract, what is the volume and pressure?

ventricular volume is low

pressure is high

AV valves close

T/F All of the blood from the atria flows passively into ventricles

FALSE- final 1/3 is contracted into the ventricles

What is valvular insufficiency?

any failure of a valve to prevent reflux, backward flow of blood

results form rheumatic fever→ autoimmune attack on the mitral aortic valves

What is a heart murmur?

abnormal heart sound produced by regurgitation of blood through incompetent valves

What can cause diastolic murmurs?

1. Aortic regurgitation

2. Mitral stenosis

3. Pulmonic regurgitation

4. Tricuspid stenosis

What can cause a systolic murmur?

1. Mitral regurgutation

2. Aortic stenosis

3. Tricuspid regurugitation

4. Pulmonic stenosis

5. Mitral prolapse

What is the S1 of a heart sound?

closer of AV valves

What is the S2 of a heart sound?

closure of the semilunar valves

What is the S3 of heart sound?

when mitral valve opens→ may be heard in youth, athletes, and pregnant women

if heard later in life, may indicate congestive heart failure

What is the S4 of the heart sound?

contraction of the atria pushing blood into a stiff or hypertrophic ventricle indicating failure of left ventricle

What is end diastolic volume?

volume in ventricles at the end of filling

What is end systolic volume?

volume in ventricles at end of ejection