Physiology Terms III

Why is the plateau phase of cardiac cells significant?

The cardiac plateau phase in a cardiac muscle prevents muscle contraction because of a long refractory period.

Electrocardiogram (ECG or EKG)

Recording of the electrical activity of the heart generated by the cardiac action potential at the skin surface.

Lead

Angle at which to look at the heart

In an EKG, if all sensors are sensing the same electrical activity, what is displayed on the graph?

A horizontal line

In an EKG, if one sensor senses an electrical activity differing from other sensors, what is displayed on the graph?

Distinctive changes in the graph, wave-like

The P wave represents...

Atrial Depolarization

QRS complex represents

Ventricular Depolarization and Atrial Repolarization

The T wave represents..

Ventricular Repolarization

From the information from the EKG, we can detect the...

heart beat

What is a segment in regard to EKG?

The time between waves

During the PQ segment, what two things occur?

(1.) Contraction of the Atria

(2.) AV nodal delay

During the ST segment, what occurs?

(1.) Contraction of the ventricle

When an increased S-T segment occurs, what happened?

A heart attack

What occurs in the T-P segment?

The heart is at rest

Active Filling

Requires energy Blood moves from the right atrium to the right ventricle and the left atrium to the left ventricle.

During the segments in an EKG, describe the shape.

The segments are horizontal lines in which all sensors detect the same electrical activity.

Another name for a heart beat

Cardiac cycle

How long does a cardiac cycle take?

800 ms

Clinical uses of ECG

(1.) Detect abnormalities in heart rate

(2.) Detect abnormalities in heart rhythm

(3.) Cardiac Myopathy

Tachycardia

Fast heart rate (>100 bpm)

Bradycardia

Slow heart rate (

Any time the heart rate increaes, the heart _______ changes

rhythm

Arrythmia

any variation in rhythm

Preventricular Contractions

ectopic pacemaker, skipping of heart beats

When someone has cardiac myopathy, they may have...

tissue necrosis

Different leads give different...

EKG waves

Spacing between waves displays the ______ of the heart.

rhthym

Heart Block

There is some scarring or damage on the AV node or the Bundle of His, in which the signals from the atria are delayed or blocked from reaching the ventricles

Characteristics of EKG

(1.) non-invasive

(2.) Beneficial to identifying heart conditions

Atrial Fibrillation

Independent contraction and relaxation of atrial heart contractile cells in which the APs are not sent to the neighbor.

Ventricular Fibrillation

Independent contraction and relaxation of ventricular heart contractile cells in which the APs are not sent to the neighbor.

AED Defibrillator

a device that delivers an electric shock to the heart to restore its normal rhythm

Is atrial fibrillation or ventricular fibrillation more dangerous?

Ventricular Fibrillation

Extrasystole

Pre-mature beating of the Heart

Myocardial Infarction (Heart Attack)

Prolonged coronary blockage; a blood clot, depriving the myocardium of nutrients and not circulating wastes

Zone of infarction

Damage to tissue

Zone of Ischemia

Lack of Oxygen

Does a heart attack necessarily mean cardiac arrest?

No

Once heart tissue becomes damaged and there is a lack of oxygen, what has the tissue become?

scarred tissue

We need to have correct _______ with the waves of an EKG.

spacing.

The heart serves as a ______-pump

dual

What are the two circulatory systems in the heart?

Pulmonary Circulation and Systemic Circulation

Atrioventricular (AV) valves

separate atria and ventricles

Another name for the Right AV...

tricuspid valve

Other names for Left AV...

Biscuspid valve, mitral

semilunar valves

separate the ventricle and artery

Another name for Right Semilunar

Pulmonary Valve

Another name for Left Semilunar

Aortic Valve

Can all four valves of the heart be open at the same time?

No

All 4 Valves will be all closed at ____ distinct points in a heart beat.

two

How do the valves of the heart open?

Differences in blood pressure

When pressure is high in the right atrium and low in the right ventricle, what occurs?

The tricuspid (AV) valve opens

When pressure is low in the right atrium and high in the right ventricle, what occurs?

The tricuspid (AV) valve closes

What do the Chordae tendineae and papillary muscles prevent?

They prevent AV valves from collapsing during contraction and prevent regurgitation.

If AV valves are open, then ______ valves are closed.

semilunar

What is contracting when the AV valves are open, then the semilunar valves are closed?

The atria contracts

What is contracting when the semilunar valves are open, then the AV valves are closed?

the ventricle contracts

Diastole

the heart is at rest

Systole

The heart is contracting

In the late diastole, we are at the _-_ segment.

T,P

Passive Filling

A period during diastole in which blood flows through the atria and the ventricles with no energy required

After the atrium is depolarized, ______ systole occcurs.

atrial

active filling

The heart is consuming energy to move blood from the atria to the ventricles

Isovolumic Ventricular Contraction

The pressure has increased enough that the AV valves are closed, but the semilunar valves are not open yet.

Ventricular Ejection

Pressure has increased substantially, in which the pressure in the ventricle is greater than the corresponding artery, so the semilunar valves open, and blood is ejected from the ventricle

What segment of the EKG occurs when Ventricular Ejection happens?

S-T segment

Isovolumetric Ventricular Relaxation

As ventricles repolarize, they relax, and the volume increases while the pressure decreases, which causes the semilunar valves to close.

Cardiac Diastole

The entire heart is at rest

During an atrial systole, a _______ potential occurs.

action

When the aorta pressure decreases in the Wigger's Diagram, what occurs?

Blood moving from the aorta to the rest of the body

The lowest pressure of the Aorta happens at the end of _________ ___________?

Ventricular Diastole

What is the lowest pressure in Ventricular Diastole?

80 mm Hg

The highest pressure of the Aorta happens during _________ ___________?

Ventricular Systole

What is the highest pressure in Ventricular Systole?

120 mm Hg

The right side of the heart has a __________ pressure than the left side of the heart.

lower

Why does the right side have a lower pressure than the left side of the heart?

The right side of the heart has a LOWER pressure than the left side because the left side has to pump to the entire body, while the right side has to pump to the lungs.

End Systolic Volume (ESV)

65 mL

What is the End Diastole Volume (EDV)

135 mL

At resting heart rate, the heart has a __________, a ________ supply.

resorvoir, blood

Passive Filling is _____ important than Active Filling.

More

The maximum blood volume of the ventricle happens at the end of __________ ______.

ventricular diastole

The right and left sides of the heart have approximately the same ________ of blood

volume

The Lub sound of the heart is caused by...

AV Valves CLose

The Dub sound of the heart is caused by...

Semilunar Valves Close

At the peak of ventricle volume, what valve(s) are open?

semilunar valves

Stroke Volume (SV)

The amount of blood pumped by one ventricle during a single contraction

Formula for Stroke Volume

SV = EDV - ESV

Cardiac Output (CO)

The volume of blood pumped by one ventricle in a given period of time

Cardiac Output Equation

CO = HR x SV

Average CO output in an Adult

5 L/min

An adult has __ L of blood!

5

Epi and NE bind to what receptors of the heart?

β-1 adrenergic

β-1 adrenergic receptors increase what secondary messenger?

cAMP

Increase in cAMP regarding the sympathetic system does what three things?

(1.) Increase Sodium Entry - Faster Heart Rate

(2.) Increased Calcium Entry and Release - Stronger Contraction

(3.) Calcium Pumping Back into the SER - Shortens Systole

We want to keep the _____ occurring as long as possible to allow _______ filling to occur for the longest.

diastolic, passive

Explain the Arrow Diagram for the Parasympathetic Pathway for the Heart.

Ach -> Muscarinic -> Closes K⁺ channels more slowly -> Decreases Heart Rate

Extrinsic Control in regards to Stroke Volume

Use of hormones and neurotransmitters to affect stroke volume

Intrinsic Control in regards to Stroke Volume

Controlled by the heart to affect stroke volume

End-diastolic volume is related to...

cardiac muscle fiber length

Stroke volume is related to...

muscle tension