Ch21 Heart
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Transcript of Ch21 Heart
HUMAN ANATOMYFifth Edition
Chapter 1 Lecture
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings
Chapter 21 Lecture
Frederic MartiniMichael Timmons
Robert Tallitsch
Chapter 21The Cardiovascular System: The Heart
Introduction
• The blood must stay in motion to maintain homeostasis. – The heart keeps blood moving.
• The volume of blood pumped by the heart can vary widely, between 5 and 30 liters per minute.
An Overview of the Cardiovascular System
• The heart is a small organ; it is roughly the size of a clenched fist.
• The heart has four muscular chambers:– Right and left atria – Right and left ventricles
Fig
21.6
[Insert fig 21.1]
Figure 21.1 The Pulmonary and Systemic Circuits
An Overview of the Cardiovascular System
Figure 21.4 Position of the Heart
Orientation of the Heart
Figure 21.2a,b The Location of the Heart in the Thoracic Cavity
The Pericardium
The Pericardium
Figure 21.2c The Location of the Heart in the Thoracic Cavity
The Pericardium
Figure 21.2d The Location of the Heart in the Thoracic Cavity
The heart wall
• Parietal pericardium
• Epicardium/visceral pericardium
• Myocardium-cardiac muscle tissue
• Endocardium-– epithelia tissue
Fig
21.3
Intercalated discs & gap junctions
• Intercalated discs hold adjacent cardiac muscle cells together– Cells work together during contraction– Mechanically links cells together
• Gap junctions allow ions to pass from cell to cell– Electrical stimulation in one cell can pass directly
into other cells– Electrically/chemically links cells together
• Cardiac muscle cells work as a well organized unit
Figure 21.3c-e Cardiac Muscle Tissue
Structure of the Heart Wall
Fig
21.5
Fig
21.5
Fig
21.6
Figure 21.6d Horizontal Section of Heart
Internal Anatomy and Organization of the Heart
Heart valves
• Heart valves allow blood to flow only in one direction thru the heart
• Atrioventricular valves (AV)-between an atrium and ventricle
• rt. atrium>Rt. AV (tricuspid) valve>rt. ventricle
• lt. atrium>Lt. AV (bicuspid/mitral) valve>lt. ventricle
Figure 21.7a Valves with Ventricles Relaxed
The Structure and Function of Heart Valves
• Semilunar valves-between the ventricle & an artery
• lt. ventricle>Aortic semilunar valve>aorta
• rt. ventricle>Pulmonary semilunar valve>pulmonary artery
Figure 21.7b Valves with Ventricles Contracted
The Structure and Function of Heart Valves
Figure 21.9a Anterior Heart Figure 21.9b Posterior Heart
Coronary Circulation
Pulmonary circuit - from heart
to lungs
back to heart
Systemic circuit- from heart
to body
back to heart
Atria vs. ventricles
• Blood enters the heart via atria
• Atria have thinner walls than ventricles
• Atria pump blood to the ventricles
• Ventricles pump blood thru the pulmonary and the systemic circuit
Right vs. Left ventricle
The left Ventricle has a much thicker myocardium
Fig 21.6
Heart sounds
The two heart sounds are:• “Lub”-AV valves closing• “Dub”-semilunar valves closing
• Aortic-2nd intercostals space (Right side)• Pulmonary- 2nd ICS (Left side)• Right AV valve- 5th ICS (Right of sternum)• Left AV valve- 5th ICS (inferior to left nipple)
Heart Valves and Heart Sounds
• Placement of a stethoscope varies depending on which heart sounds and valves are of interest.
• Closure of the AV valves create the 1st heart sound (‘lub’).
• Closure of the semilunar valves create the 2nd heart sound (‘dub’).
The cardiac cycle
• A chamber of the heart can be in one of two phases:
• Systole-contraction of the muscle, ejecting blood out of the chamber
• Diastole-relaxation of the muscle, the chamber fills with blood
• The heart pumps by using cycles of systole and diastole
Cardiac Cycle
• Systole: contraction phase
• Diastole: relaxation phase
Mid-to-late diastole.
Early diastole Ventricular
systole
lub
dub
Nodal cells
• Nodal cells spontaneously depolarize causing an action potential
• Two groups of nodal cells:– Sinoatrial (SA) node-makes 80-100 AP/min
• Primary pacemaker• Posterior wall of the rt. atrium
– Atrioventricular AV node-slower than SA node• Secondary pacemeker• Inferior region of the rt. Atrium wall
Figure 49.7 The Heartbeat
Electrical Conduction System
1. Sino Atrial (SA) Node
2. Atrial Ventricular (AV) Node
3. AV Bundle (Bundle of His)
4. L and R Bundle Branches
5. Purkinje Fibers
Figure 21.11 The Cardiac Cycle
The Cardiac Cycle
Fig 21.12
The electrical signal stimulates contraction of the chambers
Pressure in left ventricle
Pressure in aorta
P (
mm
Hg)
Left ventricular volume
V (
ml)
Ventriclecontracting
Rightatrium
Rightventricle Left
ventricle
Left atrium
Ventriclerelaxing
Figure 49.4 The Cardiac Cycle
EKG-electrocardiogram
• Surface electrodes can monitor the depolarization of the nodal and conducting fibers
• EKG graph gives electrical and mechanical diagnostic information
Figure 21.13 The ECG
• The stimulus for contraction is generated by pacemaker cells of the SA node.
The Autonomic Innervation of the Heart
• Modified by the ANS
• Modified by Hormones
Autonomic Control of Heart Rate
• Basic rate established by pacemaker cells that inside the heart (myocardium) – called “intrinsic myogenic control”
• Modified by ANS– Parasympathetic: ACh decreases rate and
contraction force via the Vagus nerve X– Sympathetic: NE increases heart rate and
force of contraction via nerve.
Cardiac Centers in CNS
• Cardioaccelatory center– Medulla oblongata (Activates sympathetic
neurons)
• Cardioinhibitory center– Medulla oblongata (Parasympathetic neurons)
Centers receive input from• Higher centers (cerebrum)• Receptors monitoring blood pressure• Receptors monitoring dissolved gases
• Superior/Inferior Vena Cava• Rt. Atrium• Rt. Atrioventricular valve• Rt. Ventricle• Pulmonary Semilunar valve• Pulmonary Arteries• Lungs• Pulmonary Veins• Lt. Atrium• Lt. Atrioventricular valve• Lt. Ventricle• Aortic Semilunar valve• Ascending Aorta
Normal Functional Heart Anatomy
Congenital Heart Defects
Congenital Heart Defects