Transcript Review: Blood Flow Through the Heart, Pulmonary, and

Blood Flow Steps
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1. Caudal/Cranial Vena Cavae
2. Right atrium
3. Tricuspid/Right AV Valve
4. Right ventricle
5. Pulmonary/pulmonic valve
6. Pulmonary arteries
7. Lungs – pulmonary circulation
(CO2 out, O2 in)
8. Pulmonary veins
9. Left atrium
10. Mitral Valve/Left AV Valve
11. Left Ventricle
12. Aortic Valve
13. Aorta
14. Systemic circulation (O2 out,
CO2 in)
15. Caudal/Cranial Vena Cavae
Heart:
coronary circulation
The heart has its own blood
supply, the CORONARY
arteries and veins.
•The left and right coronary
arteries originate from the root of
the aorta, right behind the aortic
valve
•Cranial and caudal vena cavae
join together with the coronary
_________ that collects blood
from coronary circulation and
returns it to the right atrium
Fetus receives oxygen from mother through placenta
• Oxygenated blood flows from placenta to the fetus through umbilical
_______
• Blood from umbilical vein flows through liver (some bypasses liver via ductus
___________), into caudal vena cava, then into the right atrium
Fetal
Circulation
Bypasses in fetal circulation keep most of the blood out of pulmonary circulation
• Most blood from RA flows directly into LA through foramen _________
– Some blood does flow in the “normal” direction
• Blood from pulmonary artery flows into lungs or through ductus
___________ directly into aorta
Fetal
Circulation
• Blood travels through aorta to fetal systemic circulation. Deoxygenated
blood is sent back to mom via umbilical arteries that lead to the placenta
• After birth, ductus venosus constricts, and foramen ovale and ductus
arteriosus close
Fetal
Circulation
Cardiac Cycle
• ___________ –heart contracts and blood is ejected
• ___________ –heart relaxes and refills with blood
• Atria relax while ventricles are contracting
and vice versa
• AV valves snap shut while the atria are in
diastole.
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Atria fill with blood from the vena cavae/pulmonary
veins
• Semilunar valves open while ventricles are in
systole.
CLOSE
– Blood is ejected into the aorta/pulmonary arteries
• AV valves open while the atria are in systole.
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Blood is ejected into the ventricles
• Semilunar valves close when ventricles are
in diastole.
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Ventricles fill with blood from the atria
• Repeat
Cardiac Cycle
Review: Blood Flow Through the Heart,
Pulmonary, and Systemic Circulations
What causes the heart to pump?
Electrical impulse for heartbeat
comes from the ___________
_______ (SA node) located in
the right atrium and known as
the ______________ for the
heart.
• The SA node is a
specialized area of
cardiac muscle cells that
can generate electrical
impulses that trigger
repeated beating of the
heart.
How is electrical impulse
generated?
Depolarization and Repolarization of heart cells
– _______________: Cations are pumped out of the cell.
– _______________: Cations flow into the cell.
• Repolarization= Diastole
• Depolarization= Systole
SA Node -> AV Node -> Bundle of His -> Purkinje Fibers
• Electrical current impulse travels
from base of heart to apex of
heart.
– Cardiac muscle cells can
transmit electrical impulse from
one muscle cell to another, so
electrical impulses spread like
a wave through the heart from
one cell to the next.
• Current spreads across both atria
and causes them to contract,
pushing blood through the AV valves
into the ventricles
SA Node -> AV Node -> Bundle of His -> Purkinje Fibers
• The electrical impulse travels quickly
down the muscle fibers to the _____
_______, located near the junction of
the right atrium and right ventricle.
• Electrical impulse then spreads through
the ________ ___ ______(fibers in the
ventricles)
-Travels down the interventricular
septum to the bottom of the
ventricles
• ___________ _________carry
impulses from the Bundle of His up into
the ventricular myocardium. The
ventricles then contract (apex to
base) and blood is ejected through the
pulmonic and aortic valves.
SA Node -> AV Node -> Bundle of His -> Purkinje Fibers
Electrocardiogram
(ECG, EKG)
• We’ve learned that the heart’s contractions
are a result of electrical currents.
• An _____________________ is used to
detect the electrical currents.
– Instrument with graph paper that moves
under a stylus
– Electrodes attached to skin
– Measures depolarizations (systole)
and repolarizations (diastole)
– Electric currents cause stylus to move up
or down as the paper unrolls beneath it
to produce the ____________________.
Heart rate and various cardiac
abnormalities can be discovered by
observing a patient’s ECG
Interpreting an ECG
• ____ wave - depolarization of the atria
• ______ complex - waves created by
ventricular depolarization
• ____ wave - repolarization of the ventricles
CO (Cardiac Output)=SV (Stroke Volume) × HR (Heart Rate)
• __________ output: amount of blood that leaves heart per
minute
– Depends on:
• Stroke volume - amount of blood ejected with each cardiac
contraction
• Heart rate - frequency of heart contractions
Cardiac Output
Cardiac Output
CO = SV × HR
If a dog’s heart ejects 2mL of blood into the aorta with
every contraction (SV), and its heart rate (HR) is 100 beats
per minute, its cardiac output is 200mL/min.
Vigorous exercise results in increased
contractility, increased stroke volume,
and increased heart rate.
Starling’s Law
• Increased filling of the heart causes
stretching of the ventricular walls, which
results in increased force of cardiac
contraction and increased stroke volume.
• Changes in blood pressure may affect both stroke
volume and heart rate.
– Shock occurs when the blood pressure drops
substantially.
– Animals in shock have rapid, weak pulses.
– Because of reduced blood pressure, there is less filling of the
heart, the ventricles are not completely full, so stroke volume
decreases. Heart rate increases in shock to compensate
for the decrease in stroke volume and cardiac output.
– Types of shock:
• ______________ shock: occurs because of blood loss
• ______________ shock (allergic reactions) and
• ______________ shock (infection): blood pressure drops
because small blood vessels to the organs and tissues all
dilate at the same time.
• “______”: S1
Normal Heart
Sounds…(“lubdub”)
– Closure of atrioventricular valves
at beginning of ventricular systole
• “______”: S2
– Closure of semilunar valves at
beginning of ventricular diastole
•
Large animals - additional
heart sounds
– S3 - Rapid ventricular filling
– S4 - Contraction of atria
– not usually heard in small
animals
Valve Locations
P = Pulmonic valve
A = Aortic valve
M = Mitral valve
T = Tricuspid valve