Transcript Circulatory heart

Circulatory System: the Heart.
The heart
Chapter 19 pgs
715-743
History
• Aristotle thought the
heart was the seat of
emotion
• Not until Vesalius’
dissections did
Western science
correct its mistakes
• Eastern scientists had
it right all along
Confucius say western science needs some work
-
I am right
and a
genius.
Plato was
my teacher
and
Medieval
Scholars
love me.
Snap!
-
No, you are
dead and
wrong. I
am the
dissection
King of the
Sixteenth
Century.
Booyah!
Overview
• Cardiovascular
system = heart and
vessels, not blood
• Arteries = away from
heart
• Veins = toward heart
• Capillaries = small
vessels that connect
arteries and veins
Two major divisions
• Pulmonary circuit
takes blood to
lungs for gas
exchange
• Systemic circuit
takes oxygen rich
blood to the
organs
• Right side of heart gets O2
poor blood
– Pulmonary artery takes it
away from heart to lungs
– Pulmonary veins bring it
back O2 rich
• Left side of heart serves
systemic system
– Aorta takes O2 rich blood
out to organs
– Superior vena cava brings it
back from head, neck,
upper limbs
– Inferior vena cava brings it
back from organs below
diaphragm.
Where is your heart?
• 2/3s of it lies to the
left of the median
plane
• Adult heart 9 cm
wide at base, 13
cm long, 6 cm deep
• Weighs 300 g (10
oz)
Pericardium
• Double walled sac
enclosing heart
• In the pericardial
cavity is pericardial
fluid that allows the
heart to beat without
friction
• Pericarditis is the pain
when the membranes
are dry
Heart wall
3 layers
• Epicardium
– outer layer
– Fatty
• Myocardium
– Thickest layer
– Cardiac muscle
that pulls
against a
fibrous skeleton
of fibers
– Focuses the
movement of
electricity
• Endocardium
– Smooth inner
lining
Chambers
• Superiorly; Right and
Left atria receive
returning blood
– Have an easier
workload
• Inferiorly; Right and
Left ventricles eject
blood
Valves
• Ensure one way flow
• Made of flaps called
cusps
• Open & Close as a
result of pressure
changes
• When ventricles relax
valves are open
• Full ventricles contract
pressure pushes
valves shut
Coronary Circulation
• Getting blood to your heart
• ~3 bil beats over an 80
year life
• Needs 5% of bodies O2
– Coronary artery delivers this
• Myocardial Infarction: fat
deposits blocking arteries
leading to necrosis of
tissue
– Anastomoses: our bodies
defense
• Two arteries covering the
same area
Cardiac Surgery Incision and Cannulation
A Cannula is a flexible tube
The collar bones, angle and tip of the breast bone (sternum) guide the surgeon in making the incision
Cardiac Surgery Incision and Cannulation
The sternum is opened with a saw (sternotomy)
Cardiac Surgery Incision and Cannulation
During this operation, the tissues were covered with towels soaked in anti-septic solution. The breast
bone is spread with a retractor. Plastic tubes are placed into the major artery (aorta)
Cardiac Surgery Incision and Cannulation
and receiving chamber of the heart (right atrium)
Cardiac Surgery Incision and Cannulation
These tubes are connected to the heart lung bypass machine (pump) which supports the patient's life
while the heart is stopped during the surgery. The surgeon is assisted by a large team while
performing the surgery
Cardiac Surgery Incision and Cannulation
At the end of the surgery, the plastic tubes are removed after the heart lung bypass machine is turned
off. The sternum is closed with heavy gauge wires and the chest is closed in layers of sutures
Aerobic vs. Anaerobic
•
AAerobic activity = increases
heartrate to at least 65% of it's
maximum for an extended period
of time.
–
•
Best for cardiovascular strength,
endurance and fat burning
Anaerobic activity = activity done
in intense, short bursts (weight
lifting, sprinting, calisthenics,
etc.)
– fuel used during anaerobic
activity is glucose and glycogens
(sugars that are stored in our
bodies).
– Best for strength training and
body sculpting.
•
Aerobic activity should be the
predominant exercise for good
general health.
Cardiac Muscle and The Cardiac
Conduction System
• Cardiocytes: short,
thick branched cells
– Sarcoplasmic reticulum
is less developed, but
T-Tubules are more
developed, lots of
mitochondria
– Do very little mitosis
• Intercalated discs join
cells end to end
– Gap junctions allow
ions to flow between
cells, keeping electrical
current
Cardiac conduction system
• We’re myogenic: the signal
for the heart to beat comes
from within the heart itself
• Our brain can modify the
heartbeat, but not create it.
Disembodied hearts can
beat for hours.
• Sinoatrial (SA) node = the
pacemaker
• Atrioventricular node =
sends signals to the
ventricles
Electrical & Contractile activity
• Contraction = systole
• Relaxation = diastole
– These can apply to parts, or just ventricles
• Sinus rhythm = normal beat
– Can have ectopic focus (alternate source of beat, instead of SA
node) called nodal rhythm
• Arrhythmia = abnormal rhythm
Physiology of the SA node
• The nerves of the SA
node are always slowly
moving toward an action
potential
• So as soon as the heart
beats its already starting
toward another beat
• ~75 beats per minute
• Cardiac muscle has a
sustained contraction, and
a longer refratcory period
– This prevents tetanus:
Continual contraction
Electrocardiogram(ECG/EKG)
• Composite reading
of many action
potentials
• P wave: atria
contract
• QRS complex: AV
node fires, ventricles
start to contract
• T wave: ventricles
repolarizing
Cardiac cycle
Now, can you…
• Describe the relationship of the heart to other
thoracic structures?
• Identify the chambers and valves
• Trace the flow of blood through the heart
chambers
• Contrast cardiac vs. skeletal muscle
• Describe the physiological properties of cardiac
muscle
• Describe the heart’s electrical conduction
system