Transcript AP Biology Animal Form and Function Circulatory ppt.

AP BIOLOGY ANIMAL
FORM AND FUNCTION
Circulatory System
Circulatory System
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Transports:
Oxygen and nutrients
to cells
Takes away wastes
and CO2 from cells
Two kinds:
Open and Closed
Open Circulatory Systems
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Open: pump blood into
an internal cavity called
a hemocoel (or cavities
called sinuses)
The tissues are bathed
with an oxygen- and
nutrient-carrying fluid
called hemolymph.
Found in insects and
most mollusks
The hemolymph returns to the heart through
holes called ostia.
Closed Circulatory Systems
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Blood is the nutrientand oxygen-carrying
(and waste-carrying)
fluid.
It is carried inside
vessels called arteries
and veins.
Found in Annelids
(segmented worms),
mollusks (octopus and
squid) and vertebrates
Arteries and Veins
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Arteries—carry blood
away from the heart
to the cells
Arteries branch into
smaller and smaller
arterioles until they
reach the cellular level
as capillaries
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Veins—carry blood
back towards the
heart from the cells
Coming from
capillaries near the
cells, the blood
moves into larger
blood vessels called
venules, which
eventually merge
into veins.
The Heart
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The heart is the main
blood-pumping
mechanism of
circulatory systems.
Hearts have two types
of chambers: atriums
and ventricles
Ventricles are the
pumping, muscular
parts of the heart
Types of Hearts in Different Vertebrate
Animals
Amphibians and Reptiles
have 3-chambered
hearts (2 atrium, and 1
ventricle)
Fish—Have 2-chambered
hearts (1 atrium, 1
ventricle)
Mammals and Birds
have 4-chambered
hearts (2 atrium, and
2 ventricles)
4-Chambered Hearts of Mammals and
Birds
Chamber 1
Chamber 3
Chamber 2
Chamber 4
Flow Of Blood in 4-Chambered Hearts
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1. Deoxygenated blood
enters the right atrium through
the vena cava
2. Blood moves through the
AV valve (aka tricuspid valve)
to the right ventricle
3. The right ventricle pumps
the deoxygenated blood to
the lungs through the
semilunar valve to the
pulmonary artery.
4. Blood goes to the lungs and
gets oxygenated.
Flow Of Blood in 4-Chambered Hearts
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5. Oxygenated Blood then
returns to the heart via the
pulmonary veins and
enters the left atrium
6. Blood passes through
the AV valve (aka
bicuspid) to the left
ventricle.
7. The left ventricle pumps
the oxygenated blood out
of the heart to the body
via the aorta.
Cardiac Cycle (Heart Cycle)
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The rhythmic contraction
and relaxation of heart
muscles
Regulated by
specialized tissues in the
heart called
autorhythmic cells
These cells are selfexcitable and able to
initiate contractions
without external stimulus
by nerve cells.
Cardiac Cycle Steps
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1. The Sinoatrial node
(pacemaker), located
in the upper wall of
the right atrium,
spontaneously initiates
the cycle by
simultaneously
contracting both atria
and sending a signal
to the atrioventricular
node
2. The AV node sends an impulse
through the bundle of His, nodal
tissue that branches down
between both ventricles and then
branches into the ventricles
through the Purkinje fibers. This
impulse contracts the ventricles.
Cardiac Cycle Steps
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3. When the ventricles
contract (the systole
phase), blood is forced
through the pulmonary
arteries and the aorta.
The AV valves are
forced to close.
When the ventricles
relax (the diastole
phase), backflow into
the ventricles causes the
semilunar valves to
close.
Blood Pressure
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Hydrostatic pressure
created by the heart
forces blood to move
through the arteries.
As blood reaches the
capillaries, blood
pressure drops
dramatically and
approaches zero in the
venules.
Blood continues to flow in the veins
back to the heart, not because of
contractions of the heart, but because
of the movements of adjacent muscles
which squeeze the blood vessels.
Valves in the veins prevent backflow.
The Flow of Blood Throughout the
entire Circulatory System
The Lymphatic System
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Some of the wastes and
excess interstitial fluids
enter the circulatory
system when they
diffuse into capillaries.
The rest of the interstitial
fluids and wastes are
returned to the
circulatory system by
way of the lymphatic
system, a second
network of capillaries
and veins.
Lymphatic System Veins
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The fluid in the lymphatic
veins is called lymph.
It moves slowly through
lymphatic vessels by the
contraction of adjacent
muscles.
Valves in the lymphatic
veins prevent backflow.
Lymph returns to the blood
circulatory system through
2 ducts located in the
shoulder region.
Lymphatic System Functions
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In addition to returning
fluids to the circulatory
system, the lymphatic
system functions as a
filter.
Lymph nodes, enlarged
bodies throughout the
lymphatic system, act as
cleaning filters and as
immune response centers
that defend against
infection.
Red Blood Cells
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1. Red Blood cells
(erythrocytes), transport
oxygen and catalyze
the conversion of CO2
and H2O to H2CO3.
Mature red blood cells
lack a nucleus, thereby
maximizing hemoglobin
content and their ability
to transport O2.
White Blood Cells
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White Blood Cells, or
leukocytes, consist of
five major groups of
disease-fighting cells
that defend the body
against infection.
Platelets and Plasma
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Platelets are cell fragments
that are involved in blood
clotting.
Platelets release factors that
help convert the major
clotting agent, fibrinogen
into its active form, fibrin.
Threads of fibrin protein form
a network that stops blood
flow.
Plasma is the liquid portion
of the blood—it contains
various dissolved substances.