EKG and Electrical Pathway of the Heart

Ch 11.1 Cardiovascular

By Stacy King

• ​11.1 The Heart and Regulation and Innervation

• 11.2 EKG's

• 11.3 Perripheral Vascular System

• 11.4 Disorders and Diseases

​​thoracic cavity – behind/under sternum

above the diaphragm

between lungs tilted slightly to the left

size of a clenched fist

weighs 8–12 ounces on avg:

• 8-10 ounces for women

• 10-12 ounces for men

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Heart Location

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Multiple Choice

The average heart weighs?

• 8-12 oz

• 6-10 oz

• 12-14 oz

• 10kg

​remember the patients right

• right atrium

• right ventricle

• left atrium

• left ventricle​

​Structures that divide the chambers

• ​Interatrial septum- divides the atriums

• Interventricular septum- divides the ventricles

Chambers of the Heart

Multiple Choice

What is the arrow pointing to?

• right atrium

• left atrium

• right ventricle

• left ventricle

Multiple Choice

• Left Atrium

• Left Ventricle

• Right Atrium

• Right Ventricle

Close to prevent backflow of blood during contraction

atrioventricular (AV) valves

• tricuspid

• bicuspid (mitral)

semilunar valves​

• pulmonary

• aortic

Chordae tendineae

(heart strings) fibrous connective tissue that maintain the tension and position of the valves

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Heart Valves

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Multiple Choice

The purpose of heart valves is to 

• set the pace at which the heart beats
• prevent blood from flowing backward
• oxygenate the blood as it passes through the valve
• add minerals to the blood

Delivers deoxygenated blood to the heart​

• superior (head and neck)

• inferior (lower extremities)​

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Vena Cava​

Multiple Choice

4?

• Superior Vena Cava
• Right Pulmonary Artery
• Right Pulmonary Vein
• Inferior Vena Cava

​These transport blood between the heart and lungs

• Pulmonary artery

  • ​transport deoxygenated blood from the heart to the lungs

• Pulmonary Vein

  • transport oxygenated blood from the lungs to the heart

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​Pulmonary Vessels

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Multiple Choice

8?

• Left Atrium
• Left Pulmonary Arteries
• Left Pulmonary Veins
• Left Ventricle

Blood Flow

1. vena cava (DO)

2. right atrium (DO)

   1. tricuspid valve

3. right ventricle (DO)

   1. pulmonary valve​

4. pulmonary artery (DO)

   to lungs

5. pulmonary veins (O₂)

6. ​left atrium (O₂)

   1. ​bicuspid valve

7. left ventricle (O₂)

   1. aortic valve

8. aorta

Multiple Choice

Deoxygenated blood enters the heart at the:

• Right Ventricle
• Left Ventricle
• Right Atrium
• Left Atrium

Layers of the Heart

• Endocardium- inner layer

• Myocardium - thick muscular layer

• Epicardium - uppermost layer

Multiple Choice

The Thickest layer of the heart

• endocardium

• myocardium

• epicardium

Ventricular diastole

​ventricle relax, atria contract

Ventricular systole

ventricles contract, atria relax​

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Mean Arterial Pressure (map)

overall pressure within cardiovascular system

​

MAP = 2/3 (Diastole) + 1/3 systole

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​Cardiac Cycles

​

Multiple Choice

A patient is experiencing electrocardiogram changes. Which wave should the nurse recognize as representing ventricular repolarization?

• Q wave

• R wave

• S wave

• T wave

Amount of blood pumped by heart in 1 minute measured in liters/minute

• stroke volume

amount of blood pumped in 1 beat

• heart rate

number of beats per minute

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SV (ml/beat) x HR (beats/min) = Q (Cardiac Volume)

Ex. 72 beats/min x 70 mL/beat = 5,040 L/min

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Cardiac Output

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Multiple Choice

Which does not describe cardiac output?

• It is determined by body size and aerobic fitness

• The amount of blood pumped by the heart each minute

• It is the amount of blood pumped out of the heart each beat

• It is the product of heart rate and stroke volume

Intrinsic (ANS)

• PNS and SNS​

Extrinsic

• ​Endocrine and Baroreceptors

​Conduction System

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Regulation of the Heart

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Sympathetic

Increases rate and forces contractions

Parasympathetic (branches of Vagus n.)

Slows the heart rate

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Autonomic Regulation

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Multiple Choice

Heart rate can increase due to stimulation by this division of the autonomic nervous system?

• SNS

• PNS

• SAS

• NSS

​Hormone Regulation

• Medulla

  • epinephrine/norepinephrine

• Pituitary

  • Vasopressin ​

• Kidney

  • Renin​

• Thyroid

  • Thyroxin (T4)​

Other

​Baroreceptor - stretch/pressure

Chemoreceptor​ - O₂ , CO₂, pH blood

Extrinsic Factors

Multiple Choice

baroreceptors sense what type of mechanical stress potentially affecting a patients heart rate?

• pH

• stretch/pressure

• heat

• chemical

​Pacemaker

​The SA node or sinus node is able to spontaneous generate and propagate electrical impulses

generating the heart rate​

60-100 b​pm

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Sinoatrial node​

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Multiple Choice

What is the pacemaker of the heart?

• SA node

• AV node

• Brain

• Spinal cord

• ​SA node

  • atrium contraction​

• ​AV node

• bundle of HIS

• right and left branching purkinje fibers

  • ventricle contraction​

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​Electrical innervation of the Heart

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Multiple Choice

Which one of the following represents the correct path for the transmission of an impulse in the intrinsic conduction system of the heart?

• AV node, Bundle of His, SA node, Purkinje fibers, bundle branches
• SA node, AV node, Bundle of His, bundle branches, Purkinje fibers
• SA node, Bundle of His, AV node, Purkinje fibers, bundle branches
• SA node, Bundle of His, bundle branches, Purkinje fibers, AV node