Blood Vessels &
Blood
Blood Vessels
• The heart is the pumper
of the circulatory system,
but as the blood leaves
the heart it travels
through a network of
vessels that all serve a
very specific purpose.
– Arteries
– Capillaries
– Veins
Artery
Capillary
Vein
Arteries
• Carry blood away from
the heart.
• Main transporters of
oxygenated blood.
• Have very thick walls of
stiff connective tissue and
smooth muscle.
– Because of the pressure
from each pump of the
ventricles arteries are
elastic allowing them to
expand.
Artery
Capillaries
• The smallest blood vessels
• Connect arteries and veins.
• Only one cell thick – “Swiss
Cheese”
– Site of exchange between
blood and cells.
• Diffusion of oxygen and
nutrients into the cells.
• Diffusion of carbon dioxide
and wastes away from the
cells.
Capillary
Veins
• Carry deoxygenated blood
back to the heart.
– High in carbon dioxide and
waste products.
• Thin walls of connective
tissue and smooth muscle.
• Contain one-way valves to
keep blood from flowing
backward.
– Contractions of skeletal
muscles move the blood
inside the veins.
Through the Loops
• Heart-Lung-Heart
– From the right atrium (11) to
the right ventricle (1) blood is
pumped out the pulmonary
artery (2)to the lungs (3).
– Capillaries surrounding the
lungs drop of waste products,
carbon dioxide and water, and
pick up oxygen.
– Blood returns to the heart
through Pulmonary Veins to
the left atrium (4) and down
into the left ventricle (5).
Through the Loops
• Heart-Body-Heart
– From the left ventricle (5) blood is
pumped out of the heart through
the aorta, the largest and thickest
artery of the body.
• The aorta splits moving blood to the
head (7)and to the lower body (8).
– Oxygen is dropped off through
capillaries and waste products are
picked up.
– Blood return to the heart through
veins, superior vena cava (9) and
inferior vena cava (10) that
contain valves that prevent the
blood from flowing backward.
– Blood reenters the heart at the
right atrium (11).
Blood Pressure
• Blood pressure is the force of your blood
pushing against the walls of your arteries.
– The force is strongest when your ventricles
contract and weakest when your ventricles relax.
• Two locations you can feel your pulse at:
– Your neck
– Your wrist
Blood Pressure
• Blood pressure is read as two numbers:
– Systolic pressure – the pressure on the artery
when the ventricles contract.
– Diastolic pressure – Pressure on the artery when
the ventricles relax.
• Normal blood pressure would be 120 over 80.
Systemic Blood Pressure Readings
Chart Questions:
• Where is the blood pressure reading the
strongest? Arteries
• Is this person’s blood pressure normal? Yes
– What’s the systolic reading? 120
– What’s the diastolic reading? 80
• Where is the blood pressure the weakest?
Veins
Blood – The River of Life
• Connective tissue - connects all the body
systems.
• The average person has between 4-6 L of
blood.
• Blood is composed of 4 main components:
1.
2.
3.
4.
Plasma
Red Blood Cells (RBC)
White Blood Cells (WBC)
Platelets
1. Plasma
• 55% of the blood’s
volume.
• The liquid portion of
blood.
– 92% water.
– dissolved proteins and
nutrients.
• Yellow in color.
2. Red Blood Cells – (Erythrocytes)
• 45% of the blood’s volume.
• The most numerous cells in
whole blood.
• No nucleus - No cell division.
• Produced in the red bone marrow.
• Lifespan of 120 days.
• Looks like a pinched in ball that
forms a disc.
– Thin and flexible
Hemoglobin
• Iron containing protein
inside each red blood
cell.
– This is what makes blood
red.
– Binds to 4 oxygen
molecules.
– Uses diffusion to pick
up and drop off oxygen
and carbon dioxide
through the capillaries.
Hemoglobin – Oxygen Transport
3. White Blood Cells – (Leucocytes)
• <1% of the whole blood.
• Approximately twice the
size of red blood cells but
fewer in number.
– 700:1
• Produced in the red bone
marrow.
• Fights disease and
infection
• Lifespan of a month to
years.
4. Platelets – (Thrombocytes)
• <1% of whole blood.
• Tiny cell fragments
that stick to damaged
tissue.
• “Life savers” of the
blood.
•
At the site of a cut they form a
mesh that
becomes a clot or scab.
–
–
Number is too low =
excessive bleeding
Number is too high = clotting
• Lifespan of 10 days.
In A Drop of Blood
• In 1 drop of blood:
– 50 million RBC
– 100,000 WBC
– 2.5 million Platelets
The Lymphatic System
• As blood moves through the capillaries some
plasma leaks out and bathes the body cells
and keeps them moist - lymph.
– Too much fluid in the tissue = swelling.
• Excess fluid normally reenters the blood
stream through small vessels in the lymphatic
system.
– Prior to entering veins the lymph is filtered by
lymph nodes to remove any harmful materials.