Cardiovascular System Part 2: The Heart The Heart what it is A - - PowerPoint PPT Presentation

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Cardiovascular System Part 2: The Heart The Heart what it is A - - PowerPoint PPT Presentation

Nov 18, 2023 15 likes •345 views

Cardiovascular System Part 2: The Heart The Heart what it is A muscular double pump each with a flow circuit Pulmonary circuit Systemic circuit The chambers of the double pump Atria receive blood from the pulmonary

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SLIDE 1

Cardiovascular System Part 2: The Heart

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SLIDE 2

The Heart – what it is…

  • A muscular double pump

each with a flow circuit

– Pulmonary circuit – Systemic circuit

  • The chambers of the double

pump

– Atria

  • receive blood from the

pulmonary and systemic circuits

– Ventricles

  • the main pressure generating

chambers of the heart

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SLIDE 3

Location and Orientation within the Thorax

  • Physical Characteristics of

the Heart

– Size:

  • 12 cm. in length
  • 8 to 9 cm. in width

(at widest part)

  • 6 cm. in thickness

– Weight:

  • ♀ 230 ‐ 280 grams
  • ♂ 280 ‐ 340 grams
  • Largest organ of

the mediastinum

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SLIDE 4

Location landmarks of the Heart

  • Superior right

– at costal cartilage

  • f third rib and

sternum

  • Inferior right

– at costal cartilage

  • f sixth rib lateral

to the sternum

  • Superior left

– at costal cartilage

  • f second rib lateral

to the sternum

  • Inferior left

– lies in the fifth intercostal space at the midclavicular line

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SLIDE 5

The Pericardium

  • Pericardium

– Fibrous pericardium

  • strong layer of dense irregular connective tissue

– Serous pericardium (two layers)

  • Superficial layer = parietal serous pericardium
  • Deep layer = visceral serous

pericardium or the epicardium

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SLIDE 6

The Heart Wall

  • Epicardium

– visceral layer of the serous pericardium

  • Myocardium

– consists of cardiac muscle – Muscle arranged in circular and spiral patterns – Muscle in chambers differ in thickness

  • Endocardium

– endothelium resting on a layer of connective tissue – Lines the internal walls of the heart

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SLIDE 7

Comparison of ventricle myocardium

  • Left ventricle –

three times thicker than right

– Exerts more pumping force – Flattens right ventricle into a crescent shape

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SLIDE 8

Key Landmarks on the Heart

  • Base
  • Apex
  • Ventral
  • Dorsal
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SLIDE 9

Ventral View of Heart

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SLIDE 10

Posterior/Inferior View of Heart

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SLIDE 11

Heart Chambers

Right Atrium Right Ventricle Left Atrium Left Ventricle

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SLIDE 12

Systemic & Cardiac Circulation Right Atrioventricular Valve* Pulmonary Valve* Aortic Valve* Left Atrioventricular Valve*

Pathway of Blood Through the Heart

  • Begin oxygen‐poor blood in the superior and inferior

venae cavae and the coronary sinus

Right Atrium Right Ventricle Pulmonary Arteries Pulmonary Trunk Left Atrium Lungs Pulmonary Veins Aorta Left Ventricle

*Alternate Names exist for these valves!

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SLIDE 13

Heart Chambers

Right Atrium Right Ventricle Left Atrium Left Ventricle

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Heart Valves – Valve Structure

  • Each valve composed of:

– Endocardium with connective tissue core – Surrounded by a fibrous skeleton of dense irregular connective tissue that

  • Anchors valve cusps
  • Prevents over dilation of valve openings
  • Main point of insertion for cardiac muscle
  • Blocks direct spread of electrical impulses
  • Atrioventricular (AV) valves – between atria and

ventricles

  • Aortic and pulmonary valves – at junction of

ventricles and great arteries

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SLIDE 15

Heart Valves – Valve Structure

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SLIDE 16

Function of the Atrioventricular Valves

Figure 18.9a

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SLIDE 17

Function of the Atrioventricular Valves

Figure 18.9b

Isovolumetric Ventricular Contraction

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SLIDE 18

Function of the Semilunar Valves

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SLIDE 19

Heart Beat & Sounds

  • Heart rate of 70‐80 beats/minute at rest
  • Period of contraction = systole
  • Period of relaxation = diastole
  • “Lub‐dup” – sound of valves closing
  • First sound “lub” – the AV valves closing

– During isovolumetric ventricular contraction

  • Second sound “dup” – the semilunar valves

closing

– During isovolumetric ventricular relaxation

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SLIDE 20

Heart Sounds

  • Each valve sound –

best heard near a different heart corner

– Pulmonary valve – superior left corner – Aortic valve – superior right corner – Mitral (bicuspid) valve– at the apex – Tricuspid valve – inferior right corner

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SLIDE 21

Conducting System

  • Cardiac muscle tissue has intrinsic ability to:

– Generate and conduct impulses – Signal these cells to contract rhythmically

  • Conducting system

– A series of specialized cardiac muscle cells – Sinoatrial (SA) node sets the inherent rate of contraction

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SLIDE 22

Conducting System

Figure 18.12 Intrinsic Conduction System

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Innervation

  • Heart rate is modified by

extrinsic controls

  • Nerves to the heart

include:

– Parasympathetic branches

  • f the vagus nerve

– Sympathetic fibers – from sympathetic trunk ganglia

Figure 18.13

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SLIDE 24

Cardiac Blood Supply

  • Functional blood supply

– Coronary arteries

  • Arise from the aorta

– Located in the coronary sulcus – Main branches

  • Left and right coronary arteries
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SLIDE 25

Blood Supply to the Heart

Figure 18.14

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SLIDE 26

Disorders of the Heart

  • Coronary artery disease

– Atherosclerosis – fatty deposits – Angina pectoris – chest pain – Myocardial infarction – blocked coronary artery – Silent ischemia

  • 3 to 4 million Americans have episodes of silent ischemia. People

who have had previous heart attacks or those who have diabetes are especially at risk for developing silent ischemia.

  • Heart muscle disease (cardiomyopathy) caused by silent ischemia

is among the more common causes of heart failure in the United States.

~The American Heart Association

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SLIDE 27

Disorders of the Heart

  • Heart failure

– Progressive weakening of the heart – Cannot meet the body’s demands for oxygenated blood

  • Congestive heart failure

– Heart can’t pump strongly enough causing

  • Fluid accumulation (congestion) in lungs or body

– Fluid accumulation in lungs = left sided heart failure – Fluid accumulation in body = right sided heart failure

  • Cor pulmonale

– Enlargement and potential failure of the right ventricle

  • In response to pulmonary vasoconstricttion due to low oxygen

levels without elevated CO2…

– Vasoconstriction re‐routes blood to areas of the lungs that are still capable of oxygenating blood effectively

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SLIDE 28

Disorders of Conduction

  • Ventricular fibrillation

– Rapid, random firing of electrical impulses in the ventricles

  • Atrial fibrillation

– Multiple waves of impulses randomly signal the AV node – Signals ventricles to contract quickly and irregularly

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Congenital Heart Defects

Figure 18.17a, b

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Congenital Heart Defects

Figure 18.17c, d

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SLIDE 31

Congenital Heart Defects

Figure 18.17e, f

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The Heart in Adulthood and Old Age

  • Age‐related changes

– Hardening and thickening of valve cusps – Decline in cardiac reserve

  • Sympathetic control over heart is less efficient
  • Less severe in the physically active

– Fibrosis of cardiac muscle tissue

  • Lowers the amount of blood the heart can pump
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SLIDE 33

Too Bad Desmond had never learned to recognize the early warning signs of a heart attack!