Human Physiology Heart Chapter 9 Flashcards Quizlet PDF

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Human Physiology Heart Chapter 9 Terms in this set (45) Atrial muscle

...

ventricular muscle

...

specialized excitatory muscle fibers

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conductive muscle fibers

...

cardiac muscle

intercalated disc

In the heart how do ions move?

syncytium

2 existing syncytiums

Striated, involuntary muscle found only in the heart

specialized cell junctions between heart muscle cells that facilitate the passing of an impulse from one heart cell to the next

through the intracellular fluid

group of cardiac muscle cells that physiologically function as a unit

atrial and ventricular

How are atria and ventricles separated?

thick fibrous skeleton of heart

Resting Membrane potential of the heart

AP in contractile cell is -85mV

Liters of blood heart pumps per minute?

4-6 liters of blood

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During exercise liters of blood heart pumps

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4-7x the norm of 4-6 liters of blood per minute

per minute?

How is volume of blood pumped regulated

1. Response to changes in volume of blood flowing into the heart

Human Physiology Heart Chapter 9

preload

afterload

Chemical energy required for cardiac

the degree of tension on the muscle when it begins to contract (end of diastolic pressure when the ventricle has become filled.

the load against which the muscle exerts its contraclie force the pressure in the artery leading from the ventricle (resistancce)

heart uses primaily ATP and most of energy is released as heat

contraction

Efficiency of cardiac contraction

20-25%

the greater the heart muscle is stretched during filling, the greater is Frank-Starling Mechanism

the force of contraction and the greater the quantity of blood pumped inot the aorta

Effect of Temperature on heart function

Hyperkalemia

hypocalcemia

increases permeability and leads to increased heart rate...exercise and fever

excessive potassium in the blood causes the heart to become dialted and flaccid and slows heart rate

an abnormally low level of calcium in the blood, causes cardiac flaccidity similar to high potassium,

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Why does hypercalcemia lead to spastic

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This is because calcium can directly initiate cardiac contraction

contractions?

spastic contractions

Has sudden, violent, involuntary contractions of a muscle or a group of muscles

What occurs when potassium is increase 2-

can lead to massive heart weakness and abnormal rhythm to cause

3x the normal value?

death

Mechanism of Excitation of the heart by Sympathetic Nerves

diastole

increases heart rate and force of contration leading to increased cardiac output *no input heart rate and strength of ventricular contraction decrease

when the heart is at rest and filling with blood

Human Physiology Heart Chapter 9

systole

when the heart is contracting and movind blood

caused by the spread of depolarization through the atria, followed by How is a P wave created?

atrial contration. This causes a slight rise in the atrial pressure curve immediately after the P-wave.

How is the cardiac cycle started?

with generation of an action potential by the SA node

When extra blood flows into the ventricles, the actin and myosin Frank-Starling Mechanism

filaments are brought to a more optimal degree of overlap- this leads to a more forceful contraction

What occurs to stroke volume with

increased stroke volume

increased Frank-Starling Mechanism?

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stroke volume

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measurement of amount of blood ejected from a ventricle in one contraction

Where the right atrial wall is stretched more due to more venous Bain-Bridge effect

return and this leads to an increase in heart rate and thus cardiac output

the amount of blood pumped out by the ventricles in a given period of time cardiac output

, Volume of blood ejected from the left ventricle per minute ( heart rate x stroke volume, CO = HR (beats/minute) X SV (liters/beat) - Normal adult: 4-8 liters/minute)

Pumping effectiveness of heart controlled

the ANS

by?

How does Sympathetic affect Cardiac

Incresed Cardiac Output by more than 100%

Output?

vagal stimulation

Parasympathetic system can decrease Cardiac Output to zero.

Human Physiology Heart Chapter 9

Phase I : Period of filling Name the four phases of ventricular

Phase II: Period of isovolumic contraction

pumping.

Phase III: Period of ejection: Phase IV: Period of isovolumic relaxation

Period of Isovolumic relaxation

Period of Isovolumic contraction

Period of ejection

Aortic valve closes and the ventricular pressure falls back to the diastolic pressure level. Ventricle volume returns to 45 ml of blood

Volume of the ventricle does not change becuae all the vavles are closed

Systolic pressure rises higher as ventricle contracts more and volume decreases because aortic semilunar valve is open and blood ejects

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Ventricular volume starts at 45ml (end systolic volume) and a diastolic Period of filling

pressure near 0mmHg *End-diastolic volume is 115ml and the distolic pressure rising to 5mmHg

How much blood flows into the ventricles

80%

before contraction of atria

Artial kick fills ventricle by }

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