Transcript Cardiovascular System

Cardiovascular System
Did you know?
VERY INTERESTING!
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Your heart pumps 7,000 liters of blood through your body
DAILY?
Your heart will contract 2.5 billion times in your lifetime?
You have approximately 62.000 miles of blood vessels in your
body (that will wrap 2.5 times around the world!)
Cardiovascular circuits
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Systemic
– Delivers O2 to all cells & carries away wastes
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Pulmonary
– Delivers deoxygenated blood from
to lungs
– Delivers oxygenated blood from lungs back to
Heart Structure
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Hollow, cone-shaped muscular pump
About the size of your fist
Extends downward & to the left
“base” = top
– Just below the 2nd rib
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“apex” = triangular tip
– Ends at 5th intercostal space
Pericardium
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Fibrous pericardium (outer)
– Attaches to diaphragm, sternum,
vertebral column & large vessels
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Double layered sac
– Parietal pericardium
(Pericardial space with serous fluid)
– Visceral pericardium
Wall of the Heart
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3 layers
– Epicardium (outer)
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Reduces friction
– Myocardium
THICK
 Muscle tissue
 Fibers in planes
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– Endocardium
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Epithelium & connective tissue
Chambers
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Atria (2)
– Upper chambers
– Receive blood returning to heart
– Less muscle than ventricles
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Ventricle (2)
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Lower chambers
Receive blood from atria
Contract to pump blood out of heart into arteries
Left THICKER than right
Chambers continued
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Septum
– Separates right & left sides
– Keeps blood from mixing
Valves
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Provide one-way flow of blood
Attached to papillary muscles via
chordae tendineae
Atrioventricular valves
– Between atrium and ventricle
– TRICUSPID (right)
– MITRAL (left)
Valves continued
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Tricuspid valve
– 3 cusps
– Separates right atrium & right ventricle
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Mitral valve
– 2 cusps
– Separates left atrium & left ventricle
Valves continued
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Pulmonary valve
– Semilunar
– Separates right ventricle and pulmonary
artery
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Aortic valve
– Semilunar
– Separates left ventricle and aortic arch
Major blood vessels
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Superior vena cava
Inferior vena cava
Coronary sinus
Pulmonary trunk
Pulmonary veins
Aorta
Blood supply to the heart
AORTA
Coronary arteries 1st branches of aorta
ANASTOMOSES
“detours”
Myocardial
capillaries
Exchange with cells
Cardiac veins
Carries deoxygenated
blood
Coronary sinus
Returns blood to
RIGHT atrium
Cardiac Muscle Fibers
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Functional syncytium
– Group of cells that function as a unit
– One stimulus causes the entire area to
contract
– 2 units
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Artrial walls
Ventricular walls
Cardiac Conduction
System
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Clumps of specialized muscle tissues
Only initiate and distribute impulses
DON’T CONTRACT!
2 nodes
– SINOATRIAL NODE (S-A node)
– ATRIOVENTRICULAR NODE (A-V node)
Heart Actions
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One complete cardiac cycle = 1 beat
– Ventricles contract = SYSTOLE
A-V valves closed; semi lunar valves open
 Blood into aorta & pulmonary artery
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– Ventricle relaxed = DIASTOLE
Atria contract; fill ventricles
 Semi-lunar valves closed; A-V valves open
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– Brief pause
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Both relaxed
Cardiac Cycle
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PRESSURE GRADIENT!
– Always flows from high to low
– Causes valves to open and close
– Think of door being blown open & closed
by wind
Sinoatrial Node
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Initiates impulses that spread through
the mycardium & stimulate muscle
contraction
Rhythmic “pacemaker”
– Average 70-80 times/minute
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DOES NOT directly cause ventricle
contraction!
Atrioventricular Node
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Conduction path between atrium &
ventrical syncytia
Junctional fibers
Cardiac
Conduction
System
Sinoatrial node
Atrial syncytium
Junctional fibers
Atrioventricular node
HIS bundle
Bundle branches (R&L)
Purkinje fibers
Ventricular syncytium
to papillary muscles
Electrocardiogram
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Used to assess electrical
conduction in the heart
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P = S-A node triggers (atrium contract)
QRS = ventricles contract
T = Pause
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P-Q interval SHOULD be short!
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Electrocardiogram (EKG)
Electrocardiogram &
Cardiac Conduction
System Animation
Regulation of the Cardiac
Cycle
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Medulla Oblongata
– Blood pressure change
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Cerebrum & hypothalamus
– Emotional upset
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FAINTING: low heart rate
– Anxiety
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High heart rate
Regulation of the Cardiac
Cycle
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Body Temperature
– Temp increase = increased heart rate
– Temp decrease = decreased heart rate
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Ion concentrations
– Hyperkalemia = high K+
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Low HR & low force of contraction
– Hypercalcemia = high Ca2+
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Abnormally LONG contraction
– Hypocalcemia = low Ca2+
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Heart action DEPRESSED
Heart Sounds
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LUBB-DUBB
– Lubb = ventricles start contraction
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A-V Valves CLOSING
– Dubb = ventricles start relaxation
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PULMONARY & AORTIC Valves CLOSING
Heart Sounds
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Murmur
– Cusps do not close completely allowing blood to
leak back into chamber
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Sounds
Blood Pressure
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Blood is pumped intermittently
– Systole: 70 mL of blood into the aorta
– Diastole: NO blood leaves heart
– SEEMS AS IF BLOOD FLOW SHOULD BE
CHOPPY…but it is NOT!
Blood Pressure
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Arterial Pressure
– Blood vessels are elastic
– Buffer changes in blood pressure
– Healthy arteries work similar to a balloon!
Arteries expand to
handle extra volume
and pressure
Heart pumps
out blood on
Systole (LUBB)
No blood leaves heart
during diastole (DUBB)
Arteries recoil &
release stored blood
What does 120/80 mm
Hg really mean?
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Normal blood pressure
– Reading shows variance of
arterial pressure
– 1st number = maximum pressure
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Systolic pressure
– 2nd number = minimum pressure
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Diastolic pressure
Measurement continued
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Pulse pressure
– Difference between systolic and diastolic
pressures
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Rigid arteries
– Increase pulse pressure
– High systolic pressure
– VERY low diastolic pressure
Arteries
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Carry blood away
Designed to handle high
pressure
– Strong
– Elastic
– 3 layered walls
Artery walls
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Tunica interna
– Simple squamous epithelium
– Smooth!
– Secretes chemicals!
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Tunica media
– Smooth muscle
– Elastic tissue
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Tunica externa
– Thin
– Connects to surronding tissues (ANCHOR)
Veins
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Run parallel to arteries
Less muscle & elastic tissue
VALVES!
– One way!
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Wider opening (lumina)