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The Cardiovascular System
Chapter 11
Heart is two pumps in one:
Right side – pulmonary circulation
Left side – systemic circulation
Heart→ Arteries → Arterioles → Capillaries → Venules→ Veins → Heart
Artery – any vessel that carries blood AWAY from the heart.
Vein – any vessel that carries blood TOWARD the heart
Parietal pericardium:
outer fibrous layer
inner serous layer
Pericardial cavity
Visceral pericardium
Pericarditis
Heart WallLayers (superficial to deep):
1. Epicardium – serous membrane
2. Myocardium – muscle layer
3. Endocardium – continuous throughout circulatory
system
Cardiac Muscle:
involuntary, striated
Intercalated discs:
gap junctions
functional syncytium
desmosomes – “spot welds”
Ventricular Geometry
LV
RV
Common Disorders
Ischemia – reduced blood flow
Hypoxia – reduced oxygen supply
Angina pectoris – “strangled chest” referred pain
Myocardial infarction – death of an area of tissue due to interrupted blood flow (“Heart attack”)
Congestive heart failure – heart is unable to supply bloodflow to body
Fibrillation – uncoordinated, unsynchronized beating of heart, no net bloodflow
Cardiac cycle
One complete heart beat:
•Systole (contraction) and
•Diastole (relaxation) of both ventricles
•Remember: Blood pressure = systole/diastole ≈ 120/80 normal average
“Heart beat”• http://www.youtube.com/watch?v=ZlB-915Cf
Cg
• http://www.youtube.com/watch?v=7eFn8Cgcx8g
• http://www.youtube.com/watch?v=NYB-rJZQt4w&feature=fvw
Know sequence of cardiac cycle
Know sequence of cardiac cycle
http://www.youtube.com/watch?v=12_nJamoyTk- Know
understand
Cardiac Muscle Contraction - know
• Heart muscle:– Is stimulated by nerves and is self-excitable
(automaticity)– Contracts as a unit– Has a long (250 ms) absolute refractory period
• Cardiac muscle contraction is similar to skeletal muscle contraction
http://www.youtube.com/watch?v=IjU81a5TjZs;
http://www.dnatube.com/video/317/Beating-Heart-Cell;
http://www.youtube.com/watch?v=55tAIOcBg3w&feature=related;
http://www.youtube.com/watch?v=_gbGA5il4Sg
Heart Physiology: Intrinsic Conduction System - know• Autorhythmic cells:– Initiate action potentials – Have unstable resting potentials called
pacemaker potentials– Use calcium influx (rather than sodium) for rising
phase of the action potential
http://www.youtube.com/watch?v=Lhl897Mz-h8&feature=related; http://www.interactivephysiology.com/demo/systems/buildframes.html?cardio/actnpot/01
Pacemaker and Action Potentials of the Heart - know
Heart Physiology: Sequence of Excitation - know
• Sinoatrial (SA) node generates impulses about 75 times/minute
• Atrioventricular (AV) node delays the impulse approximately 0.1 second
• Impulse passes from atria to ventricles via the atrioventricular bundle (bundle of His)
http://www.smm.org/heart/heart/pumping.htm; http://depts.washington.edu/physdx/heart/demo.html
Heart Physiology: Sequence of Excitation - know
• AV bundle splits into two pathways in the interventricular septum (bundle branches)– Bundle branches carry the impulse toward the
apex of the heart– Purkinje fibers carry the impulse to the heart
apex and ventricular walls
Heart Physiology: Sequence of Excitation - know
Heart Excitation Related to ECG - know
Extrinsic Innervation of the Heart - know• Heart is
stimulated by the sympathetic cardioacceleratory center
• Heart is inhibited by the parasympathetic cardioinhibitory center
Electrocardiography - know• Electrical activity is recorded by
electrocardiogram (ECG)
• P wave corresponds to depolarization of SA node
• QRS complex corresponds to ventricular depolarization
• T wave corresponds to ventricular repolarization
• Atrial repolarization record is masked by the larger QRS complexhttp://www.youtube.com/watch?v=lYMSkGXFoN4&feature=related
Electrocardiography (EKG)
http://www.youtube.com/watch?v=ew6Jp74vaN4
Heart Murmurs – abnormal sounds caused by the flow of blood.
Mitral stenosis (abnormal narrowing)
Mitral valve prolapse (turns “inside out”)
1.
2.
3.
Conduction system of the heartSinoatrial (SA) node – “pacemaker’ →
Atrioventricular (AV) node →
Atrioventricular (AV) Bundle - Bundle of His→
Purkinje fibers – conduction myofibers
Ectopic pacemaker = implanted device that uses electrical impulses to reproduce or regulate the rhythms of the heart
Ectopic pacemaker
ECG (or EKG)
• An electrocardiogram (ECG / EKG) is an electrical recording of the heart and is used in the investigation of heart disease.
• Normal adult 12-lead ECG:
Abnormally slow heartbeat
Abnormally fast heartbeat
Regulation of Heart Rate
• Sympathetic N.S. increases heart rate and force of contraction through increased epinephrine secretion
• Parasympathetic N.S. decreases heart rate and force of contraction through the vagus nerve. Sends continuous impulses. Secretes acetylcholine
Other factors that influence heart rate
• Temperature• Ion concentration K+ and Ca + +
• Hormones• Hypoxia, acidosis and alkalosis slow
heart• Age• Gender• Physical fitness
Fetal Circulation
• Obtains oxygen and nutrients from maternal circulation
• Two arteries off internal iliac arteries run through umbilical cord
• Umbilical vein returns oxygenated blood
• Several shunts in fetal circulation:
•Ductus venosus – bypasses fetal liver and dumps blood from umbilical vein into inferior vena cava.
•Foramen ovale – hole in atrial septum, blood passes from right atrium to left atrium, bypassing the developing lungs
•Ductus arteriosus – connects pulmonary artery with aorta
•If does not close – patent ductus arteriosus – get mixing of venous and arterial blood.