Heart Structure - PowerPoint Presentation

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Heart StructureSlide2

Heart – located in mediastinum within the thoracic cavitySlide3

The Pericardium –

membrane surrounding heartSlide4

Serous Pericardium

= 1. Parietal - outer layer2. Visceral - inner layer (part of

epicardium

)Slide5

Layers of Heart Wall

Epicardium

– outermost layer

synonymous with visceral portion of serous membrane

Myocardium – middle layer

Cardiac muscle

Pumping chamberEndocardium – innermost layerSmooth surface to reduce frictionSlide6

Layers of Heart WallSlide7

Layers of Heart WallSlide8

Chambers of HeartSlide9

Heart Chambers and ValvesSlide10

Heart ValvesSlide11

AV Valves - structureSlide12
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Heart Chambers, Valves and VesselsSlide14

Heart Chambers, Valves, and VesselsSlide15

Pulmonary vs

Systemic CirculationSlide16
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Coronary CirculationSlide18

Homeostatic Imbalance:

Mycardial InfarctionsSlide19
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Intrinsic Conduction System of the HeartSlide21
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Intrinsic Conduction System

Also called nodal system

Sinoatrial (SA) Node = pacemaker

 Atria  Atria Contract 

Atrioventricular

(AV) Node 

Brief Delay  Atrioventricular bundle (bundle of His)  Bundle branches  Purkinje fibers  Contraction of ventricle from bottom up  Blood pushed out of ventriclesSlide23

Homeostatic Imbalances

Heart block

= Damage to AV node which allows ventricles to pump at own rate, which is typically slower than normal

Fibrillation

= rapid uncoordinated shuddering of heart muscle, makes heart useless, major cause of death from heart attacks

Tachycardia

= rapid heart rate +100bpmBradycardia = slow heart rate < 60bpmSlide24

Cardiac Cycle = .8 seconds

Sequence of Events in one heartbeat

Contraction of both atria

Contraction of both ventricles

Systole = contraction – of ventricle

Diastole = relaxation – of ventricle

Lub = closing of AV valvesDub = closing of semilunar valvesSlide25

Cardiac Cycle

Systole:

Ventricles contract

AV Close = “

Lub

”

Semi-lunar openDiastole: Ventricle relaxAV valve openSemi-lunar closed= “Dub”Slide26

Cardiac CycleSlide27
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Cardiac Output

Cardiac Output = amount of blood pumped out by EACH side of the heart in 1 minute

CO = HR X SV

HR = heart rate or beats per minute

SV = stroke volume = amount of blood pumped out be each ventricle with each heartbeat

If either HR or SV varies, the other tries to compensate to keep the cardiac output stableSlide31
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Factors Affecting Heartrate

Autonomic NS – most important external influence on heart

Sympathetic – increase heart rate

Parasympathetic – slow and steady heartrate (

vagus

nerve)

HormonesEpinephrine and thyroxine – increase heartratePhysical factorsAge, gender, exercise, body temperatureSlide33

Factors Affecting Stroke Volume

How much cardiac muscle stretched before contraction

More stretch = more contraction

Venous return determines amount of stretch

Greater venous return = Greater SV

Increase SV

Slow HeartrateExerciseDecrease SVSevere blood lossVery Rapid heartrateSlide34
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Regulation of Heart Rate =

most important external influence on heart rateSlide36

Homeostatic Imbalance: Congestive Heart Failure

When the pumping efficiency of the heart is depressed so that circulation is inadequate to meet tissue needs

Usually progressive condition that reflects weakening of the heart by atherosclerosis, persistent high blood pressure, or multiple myocardial infarctionsSlide37

Congestive Heart Failure

Pulmonary Congestions

Left side failure

Right side pumps to lungs

Left side cannot pump to body

Blood pressure inside lungs increases and fluid leaks into lung tissue

Pulmonary edemaPerson can suffocatePeripheral CongestionRight side failureBlood backs up in systemic circulation

Edema in most distal parts of bodySlide38
Slide39

Review Questions – True of False

The ventricles contract in diastole

The AV valves are open during systole

The SA node is the pacemaker of the heart

Increased venous return will decrease stroke volume

Parasympathetic NS keeps heartrate slow and steadySlide40

ECG or EKG

electrical activity of the heart

depolarize

–

contract

repolarize

–relaxElectrocardiogramSlide41

Electrocardiogram = ECG

P wave

Depolarization of atria

Atria contract

QRS complex

Depolarization of ventricles

Repolarization of atriaVentricles contract (atria relax)T waveRepolarization of ventriclesVentricles relaxSlide42

Normal ECGSlide43

bradycardia

slow heart beat

tachycardia

fast heart beat

premature atrial contraction (PACs)

atria contracts before SA node

Cardiac ArrhythmiasSlide44

atrial fibrillation

atria contract faster than 350 bpm

premature ventricular contractions (PVCs)

ventricles contract too soon

ventricular tachycardia (VT)

ventricles, rather than SA node, cause beat

Cardiac ArrhythmiasSlide45

ventricular fibrillation (VF)

ventricles contract faster than 350 bpm

heart block

impulse from SA node to AV node

first

–

impulse delayedsecond–intermittently blocked third–completely blocked

Cardiac ArrhythmiasSlide46

blood vessels: the transport network

circulation: moving blood around the body

taking vital signs

know your numbers

Closed system – blood always in a vessel or heart

Blood Vessels and CirculationSlide47

tunica intima

innermost layer

Epithelial tissue

tunica media

middle layer

Smooth muscle

tunica externaoutermost layerConnective tissue The Three Layers of Blood VesselsSlide48
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Blood Pathway

Heart



Arteries



Arterioles 

Capillaries  Venules 

Veins 

HeartSlide51

Arteries

Carry blood AWAY from heart

Blood usually oxygenated – exception is pulmonary artery

Thick walls, narrow lumen

Walls elastic – expand and contract with pulse

Arterioles – smaller arteries

Dilate and constrict to alter blood flowEx. Muscles dilate when running Two organs blood supply never changes = brain and kidneysSlide52

Capillaries

Smallest of all blood vessels

Only one cell thick

Narrow – blood cells flow single file

Very large surface area for gas, nutrient, and waste exchange

Blood moves slower through here to allow time for exchangesSlide53

Veins

Carries deoxygenated back to the heart

Exception: Pulmonary vein

Thinner and less elastic, more flexible

Larger veins contain valves

Prevent backflow

Skeletal muscles and breathing help return blood to heartWhen inhale, drop in pressure occurs in thorax causing large veins near heart to expand and fillSlide54
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structure and function of vessels

Blood Vessels: The Transport NetworkSlide56

Factors Influencing Venous Return

Lumen of veins larger than arteries

Large veins have valves that prevent backflow

Skeletal muscles help “milk” blood through veins towards heart

When inhale, drop in pressure occurs in thorax causing large veins near heart to expand and fillSlide57

Anatomy of Capillary Bed

Two types of vessels

A.

vascular shunt

– vessel that directly connect the arteriole and

venule

at opposite ends of the bedB. true capillaries – actual exchange vessels10 – 100 per capillary bedPrecapillary sphincter surrounds each to act as cut-off valve and regulate blood flowSlide58
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Capillary Exchange

Substances tend to move into and out of body cells according to their concentration gradients.

Oxygen and nutrients: blood

 tissue cells

CO

2

and waster: tissue cells  bloodSlide61

How Solutes Move In and Out

1. Diffusion – lipid soluble

2. Endocytosis and Exocytosis – lipid insoluble

3. Intercellular clefts – special diffusion through gaps between cell membranes of adjoining cells

4. Fenestrated capillaries – special capillaries filled with pores. Found in areas where absorption and filtration importantSlide62

Fluid Movement -

due to differences in pressure

Blood pressure highest - arterial end

Fluid moves out of capillaries

Osmotic pressure highest -

venule

endFluid moves into capillariesSlide63

Homeostatic Imbalance – Varicose VeinsSlide64

Thrombophlebitis

Complication of varicose veins

Inflammation of a vein that results when a clot forms in vein with poor circulation

Common Consequence: clot detachment and pulmonary embolismSlide65

Special Circulations

Arterial Supply of Brain and Circle of Willis –

Supplied by 2 sets of arteries

These blood supplies are united by special arteries

Result is complete circle of connecting blood vessels called the circle of Willis

Protects the brain because it provides more than one route for blood to reach the brainSlide66

Special Circulations

Hepatic Portal Circulation

Veins drain the digestive organs and deliver blood to liver

Liver processes nutrients before make it to systemic circulation

Fetal Circulation

All nutrient, excretory, and gas exchange occur through placenta

Umbilical veins and arteries