Transcript 37.2: The Circulatory System

Circulatory system
 made up of 3 parts
 organ
 heart
 tissues & cells
 blood vessels
 arteries
 veins
 capillaries
 blood
 red blood cells
 plasma
Your Blood: Transport Fluid
 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.
Your Blood: Transport Fluid
Blood composition:
Plasma: 55% (liquid part)
Blood cells: 45% (red, white,
& platelets
Blood Cell production
 Stem cells
“parent” cells in
bone marrow
 differentiate into
many different
types of cells

ribs, vertebrae,
breastbone & pelvis
white blood
cells
white blood
cells
red blood
cells
Red blood cells: Oxygen carriers
 Bioconcave disc shaped,
most numerous
 No nucleus when mature;
‘live’ ≈120 days
 5-6 million RBC in one drop
of human blood
 Produced in red marrow of
long bones
 contain hemoglobin that
enables transport of O2
Hemoglobin
 Protein which binds O2
 250,000 hemoglobin 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 form blood clot
after an injury.
 Short-lived
Blood vessels
arteries
veins
artery
arterioles
venules
capillaries
arterioles
venules
veins
Arteries: Built for pressure
 Arteries
 blood flows away from heart
 thicker walls
 provide strength for high
pressure pumping of blood
 elastic & resistant
 maintains blood
pressure even
when heart relaxes
Major arteries
aorta carotid = to head
to brain & left arm
to right arm
pulmonary
artery
coronary
arteries
to body
pulmonary
artery =
to lungs
Veins: Built for flexibility
 Veins
Blood flows
toward heart
 blood returns back to heart
Open valve
 thinner-walled
 blood travels back to heart
at low speed & pressure
 far from heart
 blood flows because muscles
Closed
contract when we move
valve
 squeeze blood through veins
 one-way valves in larger veins allow blood to
flow only towards 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; one cell
layer thick
 allows diffusion of
materials across
capillary wall
 O2, CO2, H2O,
food, waste
waste
body cell
CO2
O2
food
Your Heart: The Vital Pump
 Atria: upper chamber
which receive blood
that pump blood to
ventricles
 Ventricles: muscular
walled chambers
which pump blood
from heart
left
atrium
right
atrium
left
right
ventricle
ventricle
Circulation of Blood
 2 part system
1. Circulation to lungs
 blood gets O2 from lungs
 drops off CO2 to lungs
 brings O2-rich blood from
lungs to heart
2. Circulation to body
 pumps O2-rich blood to body
 picks up nutrients from
digestive system
 collects CO2 & cell wastes
Circulation
to lungs
lungs
heart
body
Circulation
to body
Blood’s path through the heart






1. vena cava
2. right atrium
3. valve
4. right ventricle
5. valve
6. pulmonary artery
(to lungs)
Blood’s path through the heart






7. pulmonary veins
8. left atrium
9. valve
10. left ventricle
11. valve
12. aorta: largest
blood vessel in the
body
Heartbeat regulation
 The surge of blood
through an artery is
called a pulse.
 Pacemaker: initiates
heartbeat & generates
an electrical impulse
that spreads over
both atria.
Sino atrial node
(Pacemaker node)
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.
Medulla
oblongata
Control of the heart
 If the heart beats too
fast, the medulla
oblongata sends signals
that slow the
pacemaker.
 If the heart beat slows
down the medulla
oblongata sends signals
to speed up the
pacemaker and
increase the heart rate.
Medulla
oblongata
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
food
O2
CO2
waste
Circulatory System & Homeostasis
ATP
 Exercise
 heart beat faster
 need more ATP
 bring in more O2 & food; remove
food
more CO2 & waste out
O2
 Disease
 poor lung or heart function = heart
beat faster
 need to work harder to bring in
O2 & food & remove wastes
CO2
waste
Cardiovascular disease
 Atherosclerosis & Arteriosclerosis
 deposits inside arteries (plaques)
 develop in inner wall of the arteries,
narrowing their channel
normal artery hardening of arteries
Cardiovascular disease
 Atherosclerosis & Arteriosclerosis
 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 surgery
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.
Have a heart?
Ask Questions!!