Download Heart - Parma City School District

Heart = 4 chambers
• Two Atria: Right and Left Atrium - The
thin walled UPPER chambers of the heart
– receive blood, pump it down into ventricles
• Two Ventricles: Right and Left - The thick
walled LOWER chambers of the heart
– pump blood out of heart, more muscular
Correct
Position of
heart in
your body
RIGHT SIDE
LEFT SIDE
Positioning Terms:
… Are relative to the individual …
So as you look at it from the front, the
positions (left vs. right are reversed)
Heart Anatomy
MYOCARDIUM: major portion of the
heart = Cardiac Muscle Tissue
Endocardium = inner surface lining of
heart
Pericardium = membrane covering the
heart, forms a sac, filled with small amount
of fluid for lubrication
Heart Anatomy
Septum = Tissue separating left and right
sides
Valves = prevent backward flow of blood
Valves
• Atrioventricular Valve: lie between the
atria and the ventricles; supported by strong
fibrous strings called Chordae tendineae
– Right Side = Tricuspid (3 flaps)
– Left Side = Bicuspid or Mitral (2 flaps)
• Semilunar Valves: resemble “half moons”;
separate the ventricles
Flow of Blood Through the Body
• Arteries & Arterioles: carry oxygenated
blood away from the heart - brings oxygen,
nutrients, amino acids, glucose to tissues
• Veins & Venules: carry deoxygenated
blood back to the heart, removes wastes
• Capillaries: Exchange material at the
tissues
Blood Circuits
• Pulmonary = Heart ---> Lungs --->
Heart
• Systemic = Heart ---> Rest of Body --->
Heart
Left ventricle has the harder job of
pumping blood to the entire body so its
walls are thicker than the right ventricle
which pumps blood only to the lungs
The Path of Blood in the Heart
1. Superior and Inferior Vena Cava
return deoxygenated blood to the RIGHT
ATRIUM
2. Right Atrium ---> atrioventricular valve
(Tricuspid) ---> RIGHT VENTRICLE
3. Right Ventricle ---> pulmonary
semilunar valve --> Pulmonary Arteries
---> Lungs
The Path of Blood in the Heart
4. Pulmonary Vein carries Oxygenated
blood from lungs to left atrium
5. Left Atrium ---> atrioventricular valve
(bicuspid valve) ---> left ventricle
6. Left Ventricle ---> Aortic Semilunar
Valve ---> rest of body
The Heartbeat
• The 2 atria contract at the same time; 2
ventricles contract at the same time
• Systole: contraction of heart muscle
• Diastole: relaxation of heart muscle
Heart beats about 70 times / minute; each
beat lasts 0.85 seconds
The Cardiac Conduction System
• The heart can beat without any nervous
stimulation!
• Nodal Tissue = has both muscular and
nervous characteristics
– SA Node (Sinoatrial): “The Pacemaker” upper
wall of right atrium, initiates heartbeat, causes
the atria to contract
– AV Node (atrioventricular): receives signal via
Purkinje fibers, causes ventricles to contract
Electrocardiogram - ECG
• Ionic changes occur during muscle
contraction that can be detected by an
electrical recording device
• P QRS T wave
– P = excitation /contraction of atria
– QRS = ventricular excitation & contraction
– T = recovery of ventricles, repolarization
Abnormal ECG
• Sinus Tachycardia:
abnormally fast heart
beat due to fast
pacemaker
• Ventricular
Fibrillation: irregular
stimulation of the
ventricles
• Mitral Stenosis:
bicuspid (mitral) valve
gets obstructed
Blood Pressure
• Pulse = expansion & recoil of arterial wall
due to surge of blood flow
• Blood Pressure = pressure of blood flow
against the wall of a blood vessel; normal is
120/80 taken at the brachial artery in the
arm (systolic / diastolic)
Sphygmomanometer
• Systolic = highest arterial pressure when
cuff is tight (Normal 120)
• Diastolic = lowest arterial pressure when
cuff is loose (Normal 80)
Fetal Circulation
• 1. Pulmonary circulation bypasses the
lungs (Foramen Ovale - one way opening
in the septum between atria)
• 2. Fetal blood flows through the placenta;
Ductus Arteriosus leads blood away from
lungs and into systemic route