The Circulatory System
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Functions of the Circulatory System
 Transports oxygen, waste and nutrients
 Carries disease-fighting materials produced
by the immune system
 Contains cell fragments and proteins for
blood clotting
 Distributes heat throughout the body to help
regulate body temperature
Blood Vessels
 Arteries
 Capillaries
 Veins
Arteries,
Capillaries,
and Veins
A. Arteries
 Blood is carried away from the heart.
 Under high pressure.
 Thicker walls
 Virtually all arteries carry oxygenated blood.
 Arteries (like veins) are surrounded by a layer
of involuntary, smooth muscle.
B. Capillaries
 Microscopic blood vessels where the exchange
of important substances and wastes occur
 The walls are only one cell thick.
C. Veins
 Carry blood back to the heart
 Usually carries deoxygenated blood.
 Under low pressure.
 Possess one-way valves to prevent back-flow
 Contraction of skeletal muscles helps keep the
blood moving.
 Veins are surrounded by smooth muscle.
Types of Muscle Cells
The Heart
 A hollow organ with 4 chambers
 Made up of cardiac muscle tissue.
Role
 Pumps oxygenated blood/nutrients to body cells.
 Pumps deoxygenated blood to the lungs to pick
up oxygen and drop off carbon dioxide.
Coronary arteries provide the heart with oxygen
and nutrients. Blockage of those arteries can
result in a heart attack.
Structure of the Heart
 Divided into four compartments called chambers
 The right atrium and the left atrium receive blood
returning to the heart.
 The right and left ventricles pump blood away
from the heart.
 A strong muscular wall (septum) separates the
left side of the heart from the right side of the
heart.
 Valves separate the atria from the ventricles and
keep blood flowing in one direction.
GREAT HEART
ANIMATION 1
GREAT HEART
ANIMATION 2
Circulatory
System
PATHWAY OF BLOOD THROUGH THE HEART
 Deoxygenated returns to the heart via the superior/inferior vena
cava and enters the right atrium. The right atrium contracts and
blood flows past the tricuspid valve into the right ventricle.
 The right ventricle contracts and forces deoxygenated blood
through the pulmonary semilunar valve into the pulmonary
arteries. Deoxygenated blood makes its way to the lungs. O2 is
picked up and carbon dioxide is dropped off.
 Oxygenated blood from the lungs returns to the left atrium of the
heart via the pulmonary veins.
 The left atrium contracts and forces blood through the mitral valve
into the muscular left ventricle.
 The left ventricle contracts and forces oxygenated blood through
the aortic semilunar valve into the ascending & descending aorta
and on to the rest of the body
How the Heart Beats (BEATING HEART)
HEART ANIMATION 1
HEART ANIMATION 2
HEART ANIMATION 3
HEART ANIMATION 4
HEART/PULSE RATE:
 Rhythmic pulsing of blood through the arteries.
 Can be felt along the wrist, neck, elbow and foot.
 Resting Pulse Rate: 60-80 beats per minute.
 Fetal heart rate can be detected at roughly 6 weeks.
BLOOD PRESSURE:
 A measure of how much pressure is exerted against the
vessel walls by the blood (120/80 mm Hg).
 120 is the systolic # (measure of the pressure against
the artery walls when the ventricles contract. 80 is the
diastolic # (measure of the pressure against the artery
walls when the ventricles relax).
Some Myocardial (Cardiac) Cells are
Autorhythmic
(Animation)
The Heart’s Electrical Conduction System
• The heart has its own ‘natural pacemaker;’ a
collection of cells called the SA (sinoatrial node).
• These cells can generate their own action
potential/electrical impulse and so the heart can
beat without direction from the nervous system.
• The impulses will travel throughout the heart to
cause contractions of the atria and ventricles.
The brain stem (medulla) via the ANS can alter heart rate
by influencing the SA Node. Hormones like epinephrine
(adrenaline) also influence the heart.
ANIMATION
THE COMPONENTS OF BLOOD
A. Plasma
 Straw-colored. Carries glucose, fats, vitamins, minerals,
hormones, and waste products from the cells
B. Red Blood Cells - Erythrocytes
 Carry oxygen to all of the body’s cells
 Consist of an iron-containing protein called
hemoglobin
 Hemoglobin chemically binds with oxygen
molecules and carries oxygen to the body’s cells.
C. Platelets - Thrombocytes
 Collect and stick to the vessel at the site of the
wound and releases chemicals that produce a
protein called fibrin.
 Fibrin is a protein that weaves a network of fibers
across the cut that traps blood platelets and red
blood cells.
D. White Blood Cells - Leukocytes
 Recognize disease-causing organisms
 Produce chemicals to fight the invaders
 Surround and ingest/kill the invaders
A macrophage engulfing bacteria
via phagocytosis
Common Circulatory System Disorders
DISORDER
CONSEQUENCES
Coronary Artery
Blockage of Blood Vessels Supplying the Heart.
Disease/Atherosclerosis Heart muscle deprived of O2
Heart Attack
(Myocardial Infarct)
Heart Muscle doesn’t receive nutrients/O2. Death of
cardiac muscle.
Cardiac Arrhythmia
Improper beating of the heart.
High Blood
Pressure (Hypertension)
The pressure against the arterial walls is too high.
Can lead to stroke.
Stroke
Interruption of Blood Flow due to rupture of blood
vessel or blockage.
These disorders can be caused by any number of factors: Genetics, Stress, Poor
Diet, Smoking, Lack of Exercise, etc.
Heart Attack/Stroke Animations
Heart Disease Facts
Additional Videos
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Bozeman Biology: The Circulatory System
CCB: Circulatory and Respiratory Systems
Bill Nye: Parts One and Two
How the Heart Pumps Blood V1, V2, V3
What is a Heart Attack?