Transcript Circulatory System

Circulatory System
Functions of Circulatory
System
• Brings oxygen, nutrients,
and hormones to cells
• Fights infection
• Regulates body temperature
Structures of Circulatory System
• Heart
• Blood
• Blood Vessels:
– Arteries
– Capillaries
– Veins
Heart
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Location: near center of chest
Composed of: muscle (myocardium)
4 chambers: 2 Atria, 2 Ventricles
Contracts ~ 72 times a minute
Pumps ~ 70 milliliters of blood with each
contraction
• During an average lifetime, the human
heart will beat more than 2.5 billion times
Heart
• Give a tennis ball a good, hard squeeze.
You're using about the same amount of
force your heart uses to pump blood out to
the body. Even at rest, the muscles of the
heart work hard--twice as hard as the leg
muscles of a person sprinting.
Blood
• Human body contains 4-6 liters
• Connective tissue containing dissolved
substances and specialized cells
– 45% cells
– 55% plasma
• 90% water
• 10% gases, salts, nutrients, enzymes,
hormones, waste products, and plasma
proteins
Blood Functions
• Collects
– oxygen from lungs
– Nutrients from digestive tract
– Wastes from tissues
• Regulate body temp
• Fight infection
• Form clots to repair damaged vessels
Blood Cells
• Red (erythrocytes)
–Most numerous 1 ml of blood = ~ 5
million RBCs
–Transport oxygen
–Get color from Hemoglobin (ironcontaining protein that binds oxygen)
–Shaped like disks w/ thick edges
–Produced from red bone marrow
–Circulate ~ 120 days before being
destroyed in liver & spleen
Blood Cells
• White (leukocytes)
–Less abundant (700 RBC to 1 WBC)
–“army” of circulatory system
–Attack foreign substances
• Platelets
–Clots blood
–Repairs damaged vessels
Figure 37-10 Blood Clotting
Section 37-2
Break in Capillary Wall
Clumping of Platelets
Clot Forms
Blood vessels injured.
Platelets clump at the site
and release thromboplastin.
Thromboplastin converts
prothrombin into thrombin..
Thrombin converts
fibrinogen into fibrin, which
causes a clot. The clot
prevents further loss of
blood..
Blood Vessels
• Arteries
–Large (“super highways”)
–Carry blood away from the heart
–Carry O2 rich blood (exception:
pulmonary artery)
Blood Vessels
• Capillaries
– Smallest (“side streets and alleys”)
– Exchange of nutrients, oxygen,
carbon dioxide, and waste
• Veins
– Return blood to heart
– Muscles help force blood through
veins against gravity
Figure 37-5 The Three
Types of Blood Vessels
Vein
Artery
Endothelium
Arteriole
Capillary
Venule
Connective
tissue
Connective
tissue
Smooth
muscle
Endothelium
Smooth
muscle
Endothelium
Valve
Path of Blood Flow
• Start in the heart:
– Left Atrium (through mitral valve)
– Left ventricle (through aortic valve)
• Leaves heart:
– Aorta
– Body/Capillaries
Path of Blood Flow
• Returns to Heart:
– Veins
– Vena Cava (inferior and Superior)
– Right atrium (through tricuspid valve)
– Right ventricle (through pulmonary valve)
• Leaves Heart:
– Pulmonary artery (goes to lungs)
• Returns to Heart:
– Through pulmonary veins to left atrium
The Circulatory System
Section 37-1
Capillaries of
head and arms
Superior
vena cava
Pulmonary
vein
Capillaries of
right lung
Aorta
Pulmonary
artery
Capillaries
of left lung
Inferior
vena cava
Capillaries of
abdominal organs
and legs
Word Bank
• Left Atrium
• Left Ventricle
• Right Atrium
• Right
Ventricle
• Pulmonary
Artery
• Pulmonary
Veins
• Aorta
• Vena Cava