Circulatory System
in Animals
Regents Biology
2008-2009
Feeding Energy Needs
 Why do we need a
circulatory system?

supplies in
 fuel (sugars)
 digestive system
 oxygen
 respiratory system

waste out
 CO2
 respiratory system

need to pick up & deliver
the supplies & wastes
around the body
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 circulatory
system
Simple organisms
When your body is only 2-cell layers thick, you can
get supplies in and waste out just through diffusion

all cells within easy reach of fluid
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Biology
Jellyfish
Hydra
Complex organisms
 Circulatory system

made up of 3 parts
 organ
 heart
 tissues & cells
 blood vessels
arteries
 veins
 capillaries
 blood
 red blood cells
 plasma

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Circulatory systems
 All animals have:
muscular pump = heart
 tubes = blood vessels
 circulatory fluid = “blood”

open
hemolymph
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closed
blood
Vertebrate Heart
 4-Chambered heart

atria (atrium)
 thin wall
 collection chamber
left
atrium
 receive blood

ventricles
 thick wall pump
right
 pump blood out atrium
Regents Biology
right
ventricle
left
ventricle
Evolution of circulatory system
Not everyone has a 4-chambered heart
fish
2 chamber
V
amphibian
3 chamber
A
A
A
V
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reptiles
3 chamber
A
V
A
V
birds & mammals
4 chamber
A
V
A
V
Lub-dub, lub-dub
 4 valves in the heart


flaps of connective tissue
prevent backflow
 Heart sounds


closing of valves
“Lub”
SL
AV
AV
 force blood against
closed AV valves

“Dub”
 force of blood against
semilunar valves
 Heart murmur
leaking valve causes hissing sound
 blood squirts backward through valve
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
Electrical signals
allows atria to empty
completely before
ventricles contract
stimulates ventricles
to contract from
bottom to top, driving
blood into arteries
 heart pumping controlled by electrical impulses
Biology
 Regents
signal
also transmitted to skin = EKG
Cardiac Cycle
ventricles
fill
How is this
reflected in
blood pressure
measurements?
systolic
________
diastolic
chambers fill
pump
(peak pressure)
_________________
fill
(minimum
pressure)
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Biology
110
________
80
ventricles
pump
Measurement of blood pressure
if systolic > 150
hypertension =
or
(high blood pressure)
if diastolic > 90
Regents Biology
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Regents Biology
2008-2009
Circulatory System
Blood Vessels
Regents Biology
2008-2009
Blood vessels
arteries
veins
artery
venules
arterioles
arterioles
capillaries
venules
veins
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Arteries: Built for their job
 Arteries
blood flows away from heart
 thicker walls

 provide strength for high
pressure pumping of blood

elastic & stretchable
 maintains blood
pressure even
when heart relaxes
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Major arteries
aorta carotid = to head
to brain & left arm
to right arm
to body
pulmonary
artery
pulmonary
coronary
artery =
arteries
to lungs
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Coronary artery bypass
bypass surgery
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Veins: Built for their job
 Veins
Blood flows
toward heart
blood returns back to heartOpen valve
 thinner-walled

 blood travels back to heart
at low speed & pressure
 why low pressure?
 far from heart
 blood flows because muscles
contract when we move
Closed valve
 squeeze blood through veins

valves in large veins
 in larger veins one-way valves
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allow blood to flow only toward heart
Major Veins
superior
vena cava =
from
upper body
pulmonary
vein =
from lung
inferior
Regentsvena
Biology cava = from lower body
pulmonary
vein =
from lung
Structure-function relationship
 Capillaries
very thin walls
 allows diffusion of
materials across
capillary

 O2, CO2, H2O,
waste
body cell
CO2
food, waste
O2
food
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Circulation of Blood
Circulation
to lungs
 2 part system

Circulation to lungs
lungs
 blood gets O2 from lungs
 drops off CO2 to lungs
 brings O2-rich blood from
lungs to heart

heart
Circulation to body
 pumps O2-rich blood to body
 picks up nutrients from
digestive system
 collects CO2 & cell wastes
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body
Circulation
to body
Vertebrate circulatory system
 2 part system
lungs
artery
to lungs
vein from lungs
to heart
heart
vein from body
to heart
body
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artery
to body
Stops along the way…
 Lungs

pick up O2 / clean out CO2
 Small Intestines

pick up nutrients from
digested food
 Large Intestines

pick up water from
digested food
 Liver

clean out worn out
blood cells
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More stops along the way…
 Kidneys
filters out wastes
(urea)
 extra salts, sugars &
water

 Bone

picks up new red
blood cells
 Spleen

picks up new white
blood cells
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Circulatory System & Homeostasis
ATP
 Homeostasis




keeping the internal environment of the
body balanced
need to balance food & O2 in
need to balance energy (ATP) production
need to balance CO2 & waste out
 Exercise

heart beat faster
food
O2
CO2
waste
 need more ATP
 bring in more O2 & food; remove more CO2 & waste out
 Disease

poor lung or heart function = heart beat faster
 need to work harder to bring in O2 & food & remove wastes
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Regents Biology
2008-2009
Circulatory System
Blood
Regents Biology
2008-2009
Blood & blood cells
 Blood is a tissue of fluid & cells

plasma
 liquid part of blood
 dissolved salts, sugars, proteins, and more

cells
 red blood cells (RBC)
 transport O2 in hemoglobin
 white blood cells (WBC)
 defense & immunity
 platelets
 blood clotting
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Blood Cell production
ribs, vertebrae,
breastbone & pelvis
 Stem cells
“parent” cells
in bone
marrow
 differentiate
into many
different types
of cells

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white blood cells
white blood
cells
red blood
cells
Red blood cells
 Small round cells
produced in bone marrow
 5 liters of blood in body
 5-6 million RBC in drop of human blood
 last 3-4 months (120 days)

 filtered out by liver
 ~3 million RBC destroyed each second
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Hemoglobin
 Protein which carries O2

250,000 hemoglobins in 1 red blood cell
O2
O2
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O2
O2
emergency repair of circulatory system
Blood clotting
chemical
emergency
signals
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platelets
seal the hole
protein fibers
build the clot
Cardiovascular disease
 Atherosclerosis & Arteriosclerosis

deposits inside arteries (plaques)
 develop in inner wall of the arteries,
narrowing their channel


increase blood pressure
increase risk of heart attack, stroke, kidney damage
normal artery
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hardening of arteries
Cardiovascular health
 Risk Factors
genetics
 diet

 high animal fat

exercise & lifestyle
 smoking
 lack of exercise
Regents Biology
bypass surgery
Heart Disease
Heart disease death rates 1996-2002
Adults ages 35 and older
Regents Biology
Women & Heart Disease
Death rates for heart disease per 100,000 women, 2002
Risk factors
 Smoking
 Lack of exercise
 High fat diet
 Overweight
 Heart disease is 3rd leading cause of death
among women aged 25–44 years & 2nd
leading cause of death among women aged
45–64 years.
Regents Biology
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Regents Biology
2008-2009