Transcript Cardiovascular circulation - Motlow State Community College

Blood Flow: Human Heart
arch of aorta
superior vena cava (from head, upper limbs)
trunk of pulmonary
arteries
right semilunar valve (shown
closed); to the pulmonary trunk
left semilunar
valve (shown
closed); to aorta
right pulmonary
veins (from lungs)
left pulmonary
veins (from lungs)
right atrium
left atrium
right AV valve
(shown open)
left AV valve
(shown open)
right ventricle
left ventricle
(muscles that
prevent valve
from everting)
endothelium
and underlying
connective tissue
inferior vena cava
(from trunk, legs)
septum (partition
between heart's
two halves)
inner layer of
pericardium
myocardium
heart’s apex
Fig. 33-11c, p.560
Circuits
• Systemic (transport of: O2, CO2, nutrients,
waste), left side
• Pulmonary (respiratory interface: O2, CO2,
exchange), right side
– heart beats about 100,000 times every day or
about 35 million beats per year
Systemic
Circuit
Longer loop that
carries blood to
and from body
tissues
capillary beds of head
and upper extremities
(to pulmonary
circuit)
aorta
(from
pulmonary
circuit)
heart
capillary beds of other
organs in thoracic cavity
capillary bed of liver
capillary beds of intestines
Pulmonary Circuit
right pulmonary artery
Short loop
that
oxygenates
blood
capillary
bed of
right
lung
left pulmonary artery
capillary bed
of left lung
pulmonary
trunk
(to systemic circuit)
(from
systemic
circuit)
pulmonary
veins
heart
lungs
Direction of Blood Flow
1.
2.
3.
4.
5.
6.
7.
8.
9.
Superior and inferior vena cava
Right atrium
Right ventricle
Pulmonary artery (Pulmonary circuit)
Pulmonary veins (Pulmonary circuit)
Left atrium
Left ventricle
Aorta
Systemic Circuit (Arteries [elastic], Arterioles,
Capillaries, Venules, Veins). Back to # 1
Figure 19.6
Cardiac Cycle
• All events associated with one heartbeat
• two atria contract
– while two ventricles relax
• two ventricles contract
– while two atria relax
Fluid pressure in
filling atria opens AV
valves; blood flows
into ventricles.
Ventricles relax
even as the
atria begin to
fill and start
another cycle.
Atria contract,
and fluid
pressure in
ventricles
rises sharply.
Ventricles
contract; blood is
pumped into the
pulmonary artery
and the aorta.
Fig. 33-12, p.561
Summary
Two simultaneous circuits: systemic and
pulmonary
Ventricles = muscular chambers of the heart that
eject blood (aorta, pulmonary arteries)
Atria = collecting chambers of the heart that
contract to fill the ventricles
• left side pumps to systemic circuit
• right side pumps to pulmonary circuit