Circulatory System - Crestwood Local Schools
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Transcript Circulatory System - Crestwood Local Schools
Circulation is the flow of blood
throughout your body. It distributes
oxygen and minerals to the cells, and
also removes waste.
› The circulatory system is vital! Without it, cells
and tissues would die
Lead to death of organism and eventually a
species
There are two main types of circulatory
systems:
› Open systems
› Closed systems
Some invertebrates don’t have one at
all; can simply diffuse in/out of the cells
right from the environment
› Doesn’t work for vertebrates!
Lack a heart or capillaries.
› Instead of a heart, there are blood vessels to
pump the blood along
› Instead of capillaries, blood vessels join
directly with open sinuses
› Blood “bathes” the organs directly, then
goes back into the vessels
Very inefficient
Works for arthropods,
insects, mollusks
(animals with lots of
openings in body to
let blood have
contact with the air)
More complex
organisms needed
something different
Has a closed system of capillaries,
arteries, and veins
› Capillaries surround organs to ensure all cells
will be nourished
Complexity of these systems varies
› Can be very simple, like annelids, or very
intricate, like humans
Much more efficient
Keeps oxygenated
and deoxygenated
blood separate
Found in most
vertebrates
(annelids, humans,
fish, frogs, etc.)
Our circulatory system consists of three
main things
› Heart
› Blood
› Blood vessels
Our heart consists of
fiber, strong muscle,
and valves
› Valves divide into 4
chambers and 2
pumps
Approximately the
size of your fist, and
weighs less than 1
pound
When resting, it beats 70 times per min.
› Each beat pumps 1/15 of a pint of blood
Individual heart cells beat at their own
tempo; as soon as two or more are
touching, they’ll synchronize.
› Coordinated by the “pacemaker”, a group
of nerves that send currents and receive
signals
The body contains 15 gallons
of blood
› Carries oxygen, minerals,
food, etc. to the cells
› Carries waste and carbon
dioxide away from the cells
› Fights disease
1/5 of our blood is always in
the lungs
Has a blue tinge when low on
oxygen
R.B.C. are responsible for carrying O
through body, and give blood its color
› Without, blood would be pale yellow
Every pinprick of blood contains about 5
million R.B.C!
250,000,000,000 in the body; about 40 for
every other cell
Arteries, veins,
capillaries
Allow blood to travel
through body
› Like a network of
roads leading to the
body’s internal
organs, tissues, cells
Keep the blood from
flowing backwards;
has distinct
pathways to follow
The first process, systemic circulation,
starts in upper left chamber of the heart
(left atrium)
Oxygenated blood flows down to the
lower left chamber (left ventricle)
› Once full, the L.V. squeezes, forcing the
blood out of the heart and through the body
Valves keep blood from flowing backwards
Have to use enough pressure to get the blood
all the way through the body!
Blood flows through the arteries
› Travels down through the body to all the
muscles and organs
All arteries eventually end in capillaries
› Very small; only 1/40 of an inch long (less
than the width of a human hair)
› The small size forces blood to slow
R.B.C. sometimes have to bend to get through
While in the
capillaries, the blood
does its job
› Drops off O and
food for cells
› Picks up waste
› Picks up carbon
dioxide
After leaving the capillaries, blood enters
the veins
› Veins push the deoxygenated blood back
up the body towards the heart and lungs
Valves keep blood from flowing down
60% of blood is always headed back towards
heart
› Veins have to flow at the same rate as
arteries, but without the initial acceleration!
(fighting gravity + capillaries slowed)
Have to be wider than the arteries
Sometimes, veins will get a little extra
help
› Leg muscles will contract to make pressure
› Once near the lungs, blood will be pushed
along by our breathing
Deoxygenated blood reaches the heart
again
› If the heart is resting, the entire process takes
about 40 seconds
The second process (pulmonary
circulation) is a much shorter journey.
› Deoxygenated blood enters the right
ventricle
› R.V. pushes blood to the lungs
› Blood picks up O and gets rid of carbon
dioxide
› Blood goes back to L.V. and everything starts
over
Mitral Valve Prolapse: one of the heart’s
valves doesn’t work, so blood can flow
backwards
› Seems to be genetic
Temporal Arteritis: inflammation of the
arteries, esp. in the head, neck, upper
body, and arms
› Can cause blindness and strokes
Endocarditis:
infection of the inner
lining of the heart
› Treatments may
include antibiotics
or surgery
The circulatory system is constantly
working with the:
› Respiratory system (getting O and getting rid
of carbon dioxide)
› Endocrine system (blood carries hormones
through the body)
Oxygenated blood travels down the
body through arteries
› Arteries end in capillaries
› Drop off food and O, pick up waste and
CO2
Deoxygenated blood travels back up
through veins
› Go back to heart, gets pushed to lungs,
picks up O
No C.S. = no life!