Transcript The Cardiovascular System

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 Wall
Layers (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=ZlB915CfCg
• http://www.youtube.com/watch?v=7eFn8Cgc
x8g
• http://www.youtube.com/watch?v=NYBrJZQt4w&feature=fvw
Know sequence of cardiac cycle
Know sequence of cardiac cycle
- Know
http://www.youtube.com/watch?v=12_nJamoyTk
understan
d
Cardiac Muscle Contraction http://www.youtube.com/watch?v=IjU81a5TjZs;
know
http://www.dnatube.com/video/317/Beating-Heart-Cell;
• http://www.youtube.com/watch?v=55tAIOcBg3w&feature=related;
Heart muscle:
– Is stimulated by nerves and is self-excitable
(automaticity)
– Contracts as a unit
– Has a long (250 ms) absolute refractory period
http://www.youtube.com/watch?v=_gbGA5il4Sg
• Cardiac muscle contraction is similar to
skeletal muscle contraction
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
cardioaccelerator
y 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
http://www.youtube.com/watch?v=lYMSkGXFoN4&feature=related
larger QRS complex
Electrocardiography (EKG)
http://www.y
outube.com/
watch?v=ew
6Jp74vaN4
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 heart
Sinoatrial (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.