cardiovascular physiology- finalf

8/13/2019 Cardiovascular Physiology- FINALf

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Cardiovascular Physiology


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Lecture Outline

Cardiovascular System Function

Functional Anatomy of the Heart

Cardiac Cycle Cardiac Output Controls & Blood Pressure


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Functional components of the cardiovascularsystem: Heart

Blood Vessels

Blood General functions these provide

Transportation Everything transported by the blood

Regulation Of the cardiovascular system Intrinsic v extrinsic

Protection Against blood loss

Production/Synthesis


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Lecture Outline



Myocardial Physiology Cardiac Cycle

Cardiac Output Controls & Blood Pressure


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Functional Anatomy of the HeartCardiac Muscle

Characteristics

Striated

Short branched cells

Uninucleate

Intercalated discs

T-tubules larger and

over z-discs


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Functional Anatomy of the HeartChambers

4 chambers

2 Atria

2 Ventricles

2 systems

Pulmonary

Systemic


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Functional Anatomy of the HeartValves

Function is to prevent backflow

Atrioventricular Valves

Prevent backflow to the atria

Prolapse is prevented by the chordae

tendinae

Tensioned by the papillary muscles

Semilunar Valves

Prevent backflow into ventricles


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Functional Anatomy of the HeartIntrinsic Conduction System

Consists of

pacemaker cells

and conduction

pathways

Coordinate the

contraction of the

atria andventricles


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Lecture Outline



Cardiac Cycle Cardiac Output Controls & Blood Pressure


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Cardiac CycleCoordinating the activity

Cardiac cycle is the sequence of events as

blood enters the atria, leaves the

ventricles and then starts over

Synchronizing this is the Intrinsic Electrical

Conduction System

Influencing the rate (chronotropy &

dromotropy) is done by the sympathetic

and parasympathetic divisions of the ANS


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Electrical Conduction Pathway Initiated by the Sino-Atrial node (SA node) which is myogenic at

70-80 action potentials/minute

Depolarization is spread through the atria via gap junctions andinternodal pathways to the Atrio-Ventricular node (AV node)

The fibrous connective tissue matrix of the heart prevents furtherspread of APs to the ventricles

A slight delay at the AV node occurs

Due to slower formation of action potentials

Allows further emptying of the atria

Action potentials travel down the Atrioventricular bundle (Bundleof His) which splits into left and right atrioventricular bundles(bundle branches) and then into the conduction myofibers(Purkinje cells)

Purkinje cells are larger in diameter & conduct impulse very rapidly

Causes the cells at the apex to contract nearly simultaneously

Good for ventricular ejection


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Electrical

Conduction

Pathway


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The electrical system gives rise to

electrical changes

(depolarization/repolarization) that is

transmitted through isotonic body fluidsand is recordable

The ECG!

A recording of electrical activity Can be mapped to the cardiac cycle


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Cardiac CyclePhases

Systole = period of contraction

Diastole = period of relaxation

Cardiac Cycle is alternating periods of systole anddiastole

Phases of the cardiac cycle1. Rest Both atria and ventricles in diastole

Blood is filling both atria and ventricles due to low pressureconditions

2. Atrial Systole

Completes ventricular filling3. Isovolumetric Ventricular Contraction

Increased pressure in the ventricles causes the AV valves toclose why?

Creates the first heart sound (lub)

Atria go back to diastole

No blood flow as semilunar valves are closed as well


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Cardiac CyclePhases

Phases of the cardiac cycle4. Ventricular Ejection

Intraventricular pressure overcomes aortic pressure

Semilunar valves open

Blood is ejected

5. Isovolumetric Ventricular Relaxation

Intraventricular pressure drops below aortic pressure

Semilunar valves close = second heart sound (dup)

Pressure still hasnt dropped enough to open AV valves so

volume remains same (isovolumetric)

Back to Atrial & Ventricular Diastole


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Cardiac CyclePhases


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Cardiac CyclePutting it all together!


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Lecture Outline



Myocardial Physiology Cardiac Cycle

Cardiac Output Controls & Blood

Pressure


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HEMODYNAMIC AFFECTING

BLOOD FLOW

BLOOD PRESSURE

RESISTANCE

VENOUS RETURN


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BLOOD PRESSURE

DURING SYSTEMIC CIRCULATION, BLOOD

PRESSURE FALLS AS THE DISTANCE

FROM THE LEFT VENTRICLE INCREASES IN ARTERIOLES AND ARTERIES35 mm Hg

IN VENOUS END OF CAPILLARIES16mm

Hg WHEN BLOOD FLOW IN RT.VENTRICLE -0

mmHg


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VASCULAR RESISTANCE

IT IS THE OPPOSTION TO BLOOD

FLOW DUE TO FRICTION

BETWEEN BLOOD AND THEWALLS OF BLOOD VESSELS.

cardiovascular physiology- finalf

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