Arteries, Veins and Capillaries
Chapter 15
The Cardiorespiratory System
• Includes function of the heart, blood vessels,
circulation, and gas exchange, between the
blood and atmosphere.
– Heart pumps blood through the body through
pathways (arteries, veins, and capillaries)
• Blood is enriched with oxygen when it passes through
the lungs
• As oxygen enters the bloodstream, carbon dioxide
leaves it (respiration)
The Circulatory System
• Course taken by blood through the arteries,
capillaries, and veins & back to heart
• Uses blood to transport dissolved materials
throughout body
– Oxygen, carbon dioxide, nutrients, waste
• Picks up waste products of cell metabolism &
takes to lungs and kidneys (to be expelled
from body)
Blood
• Only tissue that flows throughout body
• Carries oxygen & nutrients to all parts of body
and transports waste products back to lungs,
kidneys, and liver for disposal
• Essential part of immune system
• Crucial for fluid and temperature balance
• Hydraulic fluid for certain functions
• Highway for hormonal messages
• Composed of plasma and billions of cells
Plasma
 The yellowish, liquid part of blood
 River in which blood cells travel
 Makes up 55% of total volume
 Carries blood cells +
 Nutrients (sugars, amino acids, fats, salts, minerals)
 Waste products (CO2, lactic acid, urea)
 Antibodies
 Clotting proteins (called clotting factors)
 Chemical messengers (hormones)
 Proteins that help maintain body’s fluid balance
Blood—RBCs & Hemoglobin
 Red Blood Cells (erythrocytes)
 Highly specialized cells that have been “stripped” of
everything, including nucleus
 Major job: transporting oxygen
 Percentage of RBCs in total blood volume called
hematocrit
 Hemoglobin
 Special red-colored molecule that fills RBCs
 Picks up oxygen in areas where O2 is abundant and
releases O2 in tissues where O2 concentration
lowest
Blood—White Blood Cells
– 5 distinct kinds
• Neutrophils, monocytes, lymphocytes, eosinophils,
basophils
– Able to change according to need and situation in
body
– Can leave blood stream , sliding out through vessel
walls & attacking invaders at site of infections
Blood Vessels
 Hollow tubes running throughout the body
 5 types
 Arteries
 Arterioles
 Veins
 Venules
 Capillaries
 Provide 2 measurements:
 Pulse
 Blood pressure
Arteries
 Blood vessels that carry
blood from the heart to
organs & cells
 Muscular walls that allow
them to dilate or constrict
 Arterioles: very small
arteries
 Largest artery=aorta
 Runs from chest into
abdomen
 Receives blood directly
from left ventricle
Veins
• Largest vein=superior &
inferior vena cava
– Bring blood from upper
and lower body into
right atrium
• Venules: smallest veins
Capillaries
 Tiny, microscopic blood
vessels that connect arteries
to veins
 Responsible for transferring
oxygen and nutrients to cells
 Wall so thin that O2 passes
from arterial blood through
them into cells in
organs/tissues
 Waste products (CO2) pass
into capillaries to be carried
back by veins to heart/lungs
Activity
• Diagram and color Capillaries
• Vocabulary