The Circulatory
Gaiser Life Science
What do you know about the circulatory System?
“I don’t know anything.” is not an acceptable answer.
Use complete sentences.
After listening to the PowerPoint lecture, come back here
and list evidence to explain why your answer to the above
question is or is not a good answer. You may also use other
outside sources to help you respond.
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Clarifying ?s
The heart
Heart Structure
Circulatory System
1. Transports and delivers necessary materials to muscles and
Examples: Vitamins, minerals, nutrients, oxygen
2. Expels waste
Examples: carbon dioxide, ammonia, lactic acid,
and others
3. Carries red and white blood cells through the body; White blood
cells help the body fight infections and red blood cells store oxygen.
It is a hollow organ made mostly of muscle that pumps blood
through the body. It is about the size of your fist. Blood can only go
one direction through the heart.
The heart has four hollow cavities called chambers. These can be
divided into the two upper chambers called atria and two lower
chambers called ventricles.
They can then be divided into left and right sides. The left and right
sides are not connected and entirely separated by a wall of muscle.
The ventricles are connected by passageways to the atria.
These passageways are blocked by one way valves, which allow
blood to only flow from the atria to the ventricles.
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How the heart
Circulatory System
FYI: All warm blooded vertebrates (Birds and mammals) have four
chambered hearts. All cold blooded vertebrates (except
crocodilians) have three chambered hearts. Fish have 2 chambered
Since the heart and circulatory system is a closed repeating
pathway, it’s hard to say where it all starts. Let’s start with the
noise it makes - Lub-Dub.
Phase 1: The tricuspid and mitral (or bicuspid) valves close making
a sustained “Lub” sound. This begins the high pressure stage
when the blood is pumped out of the Ventricles. The right ventricle
pumps oxygen depleted blood to the lungs. The left ventricle
pumps oxygen enriched blood to the head and body.
Phase 2: The semilunar (or aortic) and pulmonary valves close
making a shorter “Dub” sound. This begins the low pressure stage
when the atria pump blood into the ventricles as they relax and
dilate. The right atrium receives oxygen depleted blood from the
head and body. The left atrium receives oxygen enriched blood from
the lungs.
Then it all starts over again, and again, and again, and again …….
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Blood Pressure
Circulatory System
- Properly called the sinoatrial node, it regulates the beating of
the heart. It’s located in the right atrium. It works together with
the atrio-ventricular node, located at the junction of the four
chambers, to control heart rate.
- blood vessels that carry blood away from the heart. Blood is
under greater pressure in the arteries - wounds spurt blood.
Blood in arteries is bright red.
- blood vessels that carry blood toward the heart. There is
less pressure in the veins - wounds ooze blood. Blood in
veins is bluish because of carbon-dioxide content.
- tiny vessels where necessary substances are exchanged
between the blood and body cells
- Anywhere the arteries pass close to the skin, there is a pulse,
which replicates the steady beat of the heart.
Examples: wrist, neck, temple, behind the knees
2 levels: high pressure or systolic when the ventricles contract
and low pressure or diastolic when the ventricles relax and
dilate. Blood pressure readings are taken with a
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Circulatory System
The blood follows a pathway from the heart to the biggest artery in
the body - the aorta, to smaller arteries, and finally to the tiniest
capillaries. Along this pathway, the blood does many things:
1. When the blood passes through the kidneys, wastes are filtered
out of the blood
2. When the blood flows through the liver, toxins such and medicine,
alcohol, and chemicals are filtered out of the blood.
3. When the blood flows the the organs, muscles and other parts of
the body, nutrients and oxygen are delivered and wastes are
picked up.
4. When the blood flows through the lungs, carbon dioxide is left
behind and oxygen is absorbed.
The pathway continues. From the tiny capillaries, the blood goes
through the smaller veins, then through the largest vein in the body the superior vena-cava, and back into the heart again.
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This PowerPoint was created by Tim Paterek. All pictures came from
Google Image Search. To fall within the Fair Use Guidelines, this
PowerPoint must be used within the confines of the classroom and may not
be published back onto the Internet unless the pictures are removed.

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