Student Chapter 20 zool

Student Chapter 20 zool - Introduction to Cardiovascular...

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Introduction to Cardiovascular System • The Pulmonary Circuit – Carries blood to and from gas exchange surfaces of lungs • The Systemic Circuit – Carries blood to and from the body • Blood alternates between pulmonary circuit and systemic circuit
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Anatomy of the Heart • Characteristics of Cardiac Muscle Cells – Small size – Single, central nucleus – Branching interconnections between cells – Intercalated discs
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Cardiac Muscle Tissue • Structure of Cardiac Tissue –Cardiac muscle is striated, found only in the heart
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Cardiac Muscle Tissue • Seven Characteristics of Cardiocytes – Unlike skeletal muscle, cardiac muscle cells ( cardiocytes ) • Are small • Have a single nucleus • Have short, wide T tubules • Have no triads • Have SR with no terminal cisternae • Are aerobic (high in myoglobin, mitochondria) •Have intercalated discs
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Cardiac Muscle Tissue Intercalated Discs – Are specialized contact points between cardiocytes – Join cell membranes of adjacent cardiocytes (gap junctions, desmosomes) – Functions of intercalated discs • Maintain structure • Enhance molecular and electrical connections • Conduct action potentials
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Cardiac Muscle Tissue Figure 10–22 Cardiac Muscle Tissue.
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Cardiac Muscle Tissue Figure 10–22a Cardiac Muscle Tissue.
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Cardiac Muscle Tissue Figure 10–22c Cardiac Muscle Tissue.
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Cardiac Muscle Tissue • Intercalated Discs – Coordination of cardiocytes • Because intercalated discs link heart cells mechanically, chemically, and electrically, the heart functions like a single, fused mass of cells
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Cardiac Muscle Tissue • Four Functions of Cardiac Tissue Automaticity • Contraction without neural stimulation • Controlled by pacemaker cells Variable contraction tension • Controlled by nervous system Extended contraction time • Ten times as long as skeletal muscle Prevention of wave summation and tetanic contractions by cell membranes • Long refractory period
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Anatomy of the Heart
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The Conducting System • Heartbeat – A single contraction of the heart – The entire heart contracts in series • First the atria • Then the ventricles
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The Conducting System • Two Types of Cardiac Muscle Cells – Conducting system • Controls and coordinates heartbeat – Contractile cells • Produce contractions that propel blood
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The Conducting System • The Cardiac Cycle – Begins with action potential at SA node • Transmitted through conducting system • Produces action potentials in cardiac muscle cells (contractile cells) – Electrocardiogram (ECG) • Electrical events in the cardiac cycle can be recorded on an electrocardiogram (ECG)
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The Conducting System • A system of specialized cardiac muscle cells – Initiates and distributes electrical impulses that stimulate contraction Automaticity – Cardiac muscle tissue contracts automatically
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The Conducting System • Structures of the Conducting System – Sinoatrial (SA) node - wall of right atrium
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Student Chapter 20 zool - Introduction to Cardiovascular...

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