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Mammalian Transport System
Ch. 8 Part 1
Cardiovascular System
• Transport system of the body
• Carries nutrients (Glucose!) and oxygen
TO the cells of the body
• Carries waste products and carbon
dioxide (CO2) AWAY from the cells
• Transports chemical messages
between cells (HORMONES)
• Fights Disease (White blood cells)
• Contains a variety of proteins
1. Heart (pump)
2. Blood Vessels
• Arteries
•arterioles
• Veins
•venuoles
• Capillaries
3. Blood
Members of the Cardiovascular System
Closed, double circulation
• Closed= b/c blood travels inside vessels
• Double circulation
• Systematic circulation
• Vessels taking blood from left ventricle in heart to
cells in tissue throughout the body and back to right
atrium
• Pulmonary circulation
• Blood taken from right ventricle to lungs and back to
left atrium
Click here to see it
in action!
The Heart
• Muscular (cardiac muscle)
organ in chest
• 2 pumps (Right and left side)
• Work together to move blood
all around your body
• Each side has a top (Atrium)
and a bottom (ventricle)
• 4 chambers of heart
• Heart muscles contract push
blood from the heart to the blood
vessels
Overview of Heart (more next week)
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Right Atrium RA
Right Ventricle RV
Left Atrium LA
Left Ventricle LV
Aorta
Superior/Inferior
Vena Cava
• Pulmonary Artery
PA
• Pulmonary Vein PV
Things to Know
• ATRIUM
• Blood is ALWAYS ENTERS atrium
• VENTRICALS
• Blood ALWAYS LEAVES the ventricles
• ARTERY
• ALWAYS carries blood AWAY from heart
• VEIN
• ALWAYS carries blood TOWARDS the heart
Anatomy of a Blood vessel
• Endothelium
• Squamous epithelium
• Single layer
• Smooth, no friction
• Rests on elastic fibers
• Tunica Media
• Middle layer
• THICKEST
• Contains:
• Smooth muscle
• Collagen
• Elastic fibers (tunica intima)
• Tunica Externa
• Outermost layer
• Contains:
• Collagen
• Elastic fibers
Blood Vessels
• Arteries
• Carry blood AWAY from heart
• Veins
• Carry blood back TO the heart
• Capillaries
• Teeny, tiny blood vessels that connect to arteries
and veins
• Nutrients and gas can pass through the capillaries
from the blood to the cells that need them
Arteries
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Elasticity important
Arteries close to heart
• Many elastic fibers in tunica media
Arteries farthest from heart
• Less elastic fibers in tunica media
• More muscle fibers
Highest pressure is in arteries
Aorta (most pressure)
Diameter= 2.5 cm
Thickness of wall = 2 mm
Arteries have mechanisms to alleviate
drastic changes in pressure
• Ventricle contracts (HP in artery)
• Arteries widen a little @ HP
• Helps decrease pressure
• Ventricle relaxes (LP in artery)
• Arteries recoil (narrow) at LP
• Helps increase pressure slightly
Capillaries
• Tiny vessels
• Just enough space for Red blood cells to
squeeze through
• Walls are one cell thick
• Endothelial cells
• Gaps in walls allow PLASMA to leak
out into tissue spaces
• Function:
• deliver nutrients, hormones, and other
body requirements to cells that make up
tissues
• remove waste products from those cells
• Small size and thin walls minimize
diffusion distance, enabling rapid
exchange
Veins
• Carry low pressure blood
back to the heart
• Walls do NOT need to be
tough or elastic
• Lumen is larger than arteries,
reduces friction that would
slow down movement of
blood
• Have SEMILUNAR VALVES
• One way valves that only
allow blood into vein (not
out)
• Moves due to contractions in
skeletal muscle, pushes blood
up against gravity
Pressure
• Highest pressure in vessels
when blood is leaving the
heart
• 120 mmHg or 16kPa
• 1 mmHg = 0.13 kPa
• Pressure changes in Circ.
Sys.
• Arteries highest blood pressure
• Pressure oscillates with heart beat
• Stretching & recoiling of artery walls helps
smooth oscillations so pressure becomes
gradually steadier the further the blood
moves along the arteries (pressure slowly
decreases)
• Capillaries Total cross-sect.
area greater than arteries that
supply them
• Blood pressure is less inside capillaries
• Veins very low pressure
• Long way from pumping effect of heart