Download Arteries

Science Module
th
7
Grade
Body Systems
Circulatory System
7th Grade Science
Background
Circulatory System
Structures
• Heart
• Blood Vessels
– Arteries
– Veins
– Capillaries
• Blood
Circulatory System
Function
• The overall function of the circulatory system is
to transport materials throughout the body
toward and away from particular target organs
and tissues.
Two Pathways
• Pulmonary Circulation
– Carries blood to lungs and back to the heart
• Systemic Circulation
– Carries blood to body and back to the heart
Your Blood Vessels:
Pathway of Circulation

3 types of vessels
– Arteries
– Capillaries
– Veins
Arteries:
carries blood Away from heart
–
–
–
–
Large
Thick-walled, Muscular
Elastic
Oxygenated blood

Exception Pulmonary Artery
– Carried under great pressure
– Steady pulsating
Capillaries
–
–
–
–
Smallest vessel
Microscopic
Walls one cell thick
Nutrients and gases diffuse here
Veins:
Carries blood to heart
–
Carries blood that contains
waste and CO2

–
–
Exception pulmonary vein
Blood not under much
pressure
Valves to prevent much
gravity pull
Your Heart: The Vital Pump
At REST, the heart
pumps about 5
QUARTS of blood a
minute.
 During EXTREME
EXERTION (exercise)
it can pump 40 quarts
a minute.

Heart:
Structure and Function
Keeps blood moving
 Large organ
composed of Cardiac
muscle

Structure of Heart

Four chambers
– Two upper (Atrium)
 Right Atrium
 Left Atrium
– Two lower
(Ventricles)
 Right Ventricle
 Left Ventricle
Bloods Path Through the Heart

Both Atrium fill at same time
– Right atrium receives oxygen POOR blood
from body via the vena cavas
– Left atrium receives oxygen RICH blood from
lungs through four pulmonary veins

After filled with blood atriums contract,
pushing blood into ventricle
Both ventricles contract
Right ventricle contracts and pushes
oxygen-poor blood toward lungs,
 against gravity,
 through pulmonary arteries
Bloods Path Through the Heart
(cont)
Left ventricle contracts and forces oxygen
rich blood
 out of heart through
 aorta (largest vessel)
The Blood
Body contains 4-6 L
 Consists of

–
–
–
–
Water
Red Blood Cells
Plasma
White blood cells and
platelets
Erythrocytes (RBC)

Transporters of
– Oxygen
– Carbon Dioxide
Leukocytes (WBC)

WBC fight infection
–


Attack foreign
substances
Less abundant
Large cells
Platelets
PLATELETS are for CLOTTING blood
 Cell fragments
 Produced in bone marrow
 Fibrin (sticky network of protein
fibers)

– Form a web trapping blood cells
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 Types
Massive loss of blood requires a transfusion
 Four Types

–A
–B
– AB
–O

Inherited from your parents
Blood Types
What happens when you mix blood
types?
 Plasma
contains proteins that
correspond to the shape of the
different antigens
 If you mix one type with the
wrong one, you get CLUMPING
Type O is the universal donor
 Type AB is the universal acceptor

What Makes Our Blood Type?
Blood Transfusions
Blood Type
of Donor
Blood Type of Recipient
A
B
AB
O
A
B
AB
O
Unsuccessful transfusion
Successful transfusion
Getting to the Heart of the Matter
http://studyjams.scholastic.com/studyjams/jams/science/humanbody/circulatory-system.htm