Circulatory System
Transports materials throughout the body
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Diffusion alone is a slow process so your body
uses the circulatory system to speed the
movement of essential nutrients and gases
Also transports hormones and waste to and from
cells
3 main components
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Heart – multi-chambered muscular organ
Blood – connective tissue made of cells and fluid
Blood vessels - muscle tissue and connective tissue
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Enable it to expand and contract as blood flows
through it
Carries material from heart to the rest of the body
and back
In the margin write two questions about the
structure and function of the C.S.
More activity requires greater
circulation….WHY?
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3 Types of Blood Vessels
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Arteries
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Veins
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Moves blood away from heart under
pressure (ensure uni-directional flow)
Thick wall of epithelial tissue wrapped in
layers of smooth muscle and connective
tissue
Muscle tissue enables the artery to
constrict and to dilate
Moves blood to the heart under less
pressure but has valves (ensure unidirectional flow)
Thinner wall of epithelial tissue relative
to arteries
Capillaries
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Walls of capillaries consist of a very thin
layer of epithelial tissue encased in a
moist membrane
Enables the diffusion of nutrients and
oxygen out of the blood and the diffusion
of waste products into the blood
How does the transport of materials
occur?
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Capillaries and cells do not come in direct
contact
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Substances enter interstitial fluid then enter
cells
Small molecules (oxygen, carbon dioxide,
waste) diffuse directly from blood cell to
somatic cell or vice versa
Larger molecules move via endocytosis and
exocytosis
Chemical Exchange
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Blood pressure forces fluid through
capillary walls.
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Artery end forces fluid out (higher blood
pressure).
Vein end allows fluid into capillary (lower
blood pressure).
Lymphatic System
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Your blood loses 4 liters of fluid into the
interstitial fluid daily.
Lymphatic systems returns this fluid to
the circulatory system near the heart.
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Made up of capillaries and larger vessels that
reach every part of the body.
Fluid is called lymph.
In the margin describe how materials such
as oxygen move from the blood into a
tissue cell. Then explain to your neighbor
the role of the lymphatic system.
The heart pumps blood throughout the
circulatory system
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Two pathways of blood flow
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The pulmonary circuit
carries oxygen-depleted
blood from the heart to the
lungs and oxygen-rich blood
back to the heart
The systemic circuit carries
oxygen-rich blood from the
heart to the rest of the body
and oxygen-depleted blood
back to the heart
Blood flows through both
circuits at the same time
Ensures that oxygen-rich
blood is constantly delivered
to cells
Pathway of Blood
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Most arteries in the body carry
oxygen-rich blood, while most
veins carry oxygen-depleted
blood
Pulmonary circuit do the exact
opposite
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Pulmonary arteries carry oxygendepleted blood to the lungs
Pulmonary veins carry oxygen-rich
blood from the lungs to the heart
Tracing the Path
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1.Blood travels from the right side
of the heart through pulmonary
arteries to the lungs.
2.Blood picks up oxygen in the
lungs.
3.Pulmonary veins return the
oxygen-rich blood to the left side of
the heart.
*Note: Pulmonary circuit
Tracing the Path
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4.Oxygen-rich blood leaves the left side of
the heart through aorta.
5.Flows through branching arteries to the
capillaries.
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Oxygen diffuses out and Carbon dioxide
diffuses in.
6.Oxygen-depleted blood returns to the
right side of the heart through veins.
*Note:Systemic Circuit
Anatomy of the Heart
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Atria (2) – upper chambers of the heart
receiving blood coming to the heart
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Ventricles (2) – lower chambers of the
heart pumping blood
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Always flow into ventricles
Thick walls due to greater blood pressure
Pericardium – fluid filled sac around heart
to cushion the organ
Valves in the heart prevent backflow of
blood into other chambers
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4 chambers is more efficient
Draw a heart, label the 4 chambers, and trace the blood flow.
Regulating Heartbeat
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Pacemaker – sets the rate for your
heart to contract
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In the walls of the right atrium
Sends electrical impulse for atrium to
contract
Sends signal to AV node which triggers
the ventricles to contract
Draw the electrocardiogram and label the stages of the heartbeat.
Controlling the Pacemaker
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Pacemaker is controlled by:
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Nervous system and the endocrine
system
Two sets of opposing nerves.
 Speed it up or slow it down.
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Hormones secreted into the blood also
control the pacemaker
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Epinephrine, aka adrenaline
Blood Pressure
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Diastole – The period of time when the heart fills with
blood between muscle contractions.
Systole - atria contract, and blood is forced into the
ventricles, which are relaxed
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Then the ventricles contract, pumping blood into arteries,
while the atria are relaxed
This cycle repeats about every second when you are
resting.
Blood pressure is represented by two numbers
separated by a slash, such as 120/70
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It is measured in millimeters of mercury (mm Hg), a
standard unit of liquid pressure
The first number is referred to as systolic pressure, the
highest recorded pressure in an artery when the ventricles
contract
Diastolic pressure, the second number, is the lowest
recorded pressure in an artery during the relaxation
phase of the heartbeat
As a person ages, blood pressure may increase
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Smoking or a fatty diet can contribute to this increase by
causing arteries to become less elastic
Summary
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At the bottom of page 1 write a
short summary about the structure
and function of the circulatory
system.
Blood consists of cells suspended in
plasma
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Function of Blood
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Deliver oxygen, water, and nutrients to
body
Remove carbon dioxide and waste
Disperse hormones throughout the
body
Fight infections and heal wounds (loose
connective tissue form matrix)
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scabs
Anatomy of Blood
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Plasma
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55% of total volume
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Red Blood Cells aka erythrocytes
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Formed in bone marrow
Carry oxygen with help from hemoglobin (protein)
Mature RBC’s lose nuclei and mitochondria which
give them their shape and make them more
efficient to transport oxygen
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90% water
10% dissolved salts and proteins
Increase surface area
White Blood Cells aka leukocytes
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Maintain their nuclei and mitochondria
Fight infections in the interstitial fluid
Blood Clotting
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Platelets – small fragments of
blood cells made in bone marrow
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Blood Clotting
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Platelets adhere to the site where
the blood vessel is damaged
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Make other nearby platelets sticky
and activate a series of reactions
among other clotting factors in the
plasma
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Break apart and release substances
called clotting factors
Result in the formation of a protein
called fibrin
Fibrin threads trap red blood cells
and additional platelets. This
network of threads and cells builds
up, eventually forming a patch that
stretches over the torn tissue
This patch dries into a scab.
Hemophilia
Check for understanding
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In the margin list four main
components of blood.
At the bottom of the page
describe what you see in the
picture below.
These are red blood cells.
What might be the impact of
RBCs this shape?