Transcript 37.2: The Circulatory System

20.1: The Circulatory System
 Section Objectives:
 Distinguish among the
various components of
blood
 Trace the route blood
takes through the
body and heart.
 Explain how heart rate
is controlled.
Circulatory system
 made up of 3 parts
 organ
 heart
 tissues & cells
 blood vessels
 arteries
 veins
 capillaries
 blood
 red blood cells
 plasma
Your Blood: Fluid Transport
 Blood is a tissue of
fluid & cells

transports O2 and
nutrients to cells
takes away CO2 and
other wastes
 Aids in fighting
disease
 Helps maintain body
temp.
Blood composition:
Plasma: 55% (liquid
part)
Blood cells: 45% (red,
white, & platelets

Blood Cell
production
ribs, vertebrae,
breastbone & pelvis
 Stem cells
“parent”
cells in bone
marrow
 differentiate
into many
different
types of
cells

white blood
cells
white blood
cells
red blood
cells
Red blood cells: Oxygen
carriers
 Bioconcave disc
shaped, most
numerous
 No nucleus when
mature, last 120 days
 5-6 million RBC in
drop of human blood
 Produced in red
marrow of long bones
 contain hemoglobin
 Hemoglobin enables
the transport of O2
Hemoglobin
 Protein which carries O2
 250,000 hemoglobins in 1 red blood
cell
O2
O2
O2
O2
White blood cells: Infection
fighters
 Largest blood cell
 play a major role in
protecting your
body from foreign
substances.
White Blood Cells
Platelets: Blood clotting
 Smallest (fragments)
 help blood clot after an
injury.
 Short-lived
Blood vessels
arteries
veins
artery
venules
arterioles
arterioles
capillaries
venules
veins
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
Major arteries
aorta carotid = to head
to brain & left arm
to right arm
to body
pulmonary
artery
pulmonary
coronary
arteries
artery =
to lungs
Veins: Built for their job
 Veins
Blood flows
toward heart
 blood returns back to heart
Open 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
 squeeze blood through veins
 valves in large veins
Closed
valve
 in larger veins one-way valves
allow blood to flow only toward heart
Major Veins
superior
vena cava
=
from
upper body
pulmonary
vein =
from lung
pulmonary
vein =
from lung
inferior
vena cava = from lower body
Structure-function relationship
 Capillaries
 very thin walls
 allows diffusion of
materials across
capillary
waste
body cell
 O2, CO2, H2O,
food, waste
CO2
O2
food
Your Heart: The Vital Pump
 Atria: upper
chamber which
receive blood that
pump blood to
 Ventricles:
muscular walled
chambers which
pump blood from
heart
left
atrium
right
atrium
right
ventricle
left
ventricle
Circulation of Blood
Circulatio
to lungs
 2 part system
 Circulation to lungs
 blood gets O2 from lungs
 drops off CO2 to lungs
 brings O2-rich blood from
lungs to heart
lungs
heart
 Circulation to body
 pumps O2-rich blood to body
 picks up nutrients from
digestive system
 collects CO2 & cell wastes
body
Circulatio
to body
Blood’s path through the heart

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



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


1. vena cavae
2. right atrium
3. valve
4. right ventricle
5. valve
6. pulmonary artery (to
lungs)
7. pulmonary veins
8. left atrium
9. valve
10. left ventricle
11. valve
12. aorta largest blood
vessel in the body.
Heartbeat regulation
 surge of blood through
an artery is called a
pulse.
Sinoatrial
node
(Pacemaker
 Pacemaker:
initiates heartbeat
generates an electrical
impulse that spreads
over both atria.
Blood pressure
 the force that the blood exerts on the blood
vessels.
 Blood pressure is measured as systolic (ventricles
contract) and diastolic (ventricles relax) pressures
Control of the heart
 A portion of the brain
called the medulla
oblongata regulates the
rate of the pacemaker,
speeding or slowing its
nerve impulses.
 If the heart beats too
fast, the medulla
oblongata, sends signals
that slow the pacemaker.
 If the heart slows down
the medulla oblongata
sends signals to speed
up the pacemaker and
increase the heart rate.
Medulla
oblongata
Circulatory System &
Homeostasis
 Homeostasis
ATP
 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
CO
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
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 hardening of arteries
Cardiovascular health
 Risk Factors
 genetics
 diet
 high animal fat
 exercise & lifestyle
 smoking
 lack of exercise
bypass surger
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.
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