Transcript CHAPTER 23 Circulation

CHAPTER 23
Circulation
Artery and vein, cross-section
•Blood smear
 It transports O2 and nutrients to cells
 It takes away CO2 and other wastes
Circulatory system
 made up of 3 parts
 organ
 heart
 tissues & cells
 blood vessels
 arteries
 veins
 capillaries
 blood
 red blood cells
 plasma
The circulatory system associates
intimately with all body tissues
 Capillaries are microscopic blood vessels
 They form an intricate network among the tissue
cells
Capillary
Red
blood
cell
The circulatory system associates
intimately with all body tissues II
 No substance has to diffuse far to enter or leave
a cell
Capillary
INTERSTITIAL
FLUID
Tissue
cell
Diffusion of
molecules
The cardiovascular system has two
circuits
 The pulmonary
circuit
 conveys blood
between the heart
and gas-exchange
tissues
 The systemic
circuit
 carries blood
between the heart
and the rest of the
body
Circulation of Blood
Circulatio
to lungs
 2 part system
 Circulation to
lungs(pulmonary)
 blood gets O2 from lungs
 drops off CO2 to lungs
 brings O2-rich blood from
lungs to heart
lungs
heart
 Circulation to
body(systemic)
 pumps O2-rich blood to body
 picks up nutrients from
digestive system
 collects CO2 & cell wastes
body
Circulatio
to body
The human heart
 4-Chambered heart
 atria (atrium)
 thin wall
 collection chamber
 receive blood
left
atrium
 ventricles
 thick wall pump
 pump blood out
right
atrium
right
ventricle
left
ventricle
Lub-dub, lub-dub
 4 valves in the heart
 flaps of connective tissue
 prevent backflow
 Heart sounds
 closing of valves
 “Lub”
 force blood against
closed AV valves
SL
AV
AV
 “Dub”
 force of blood against
semilunar valves
 Heart murmur
 leaking valve causes hissing sound
 blood squirts backward through valve
Blood’s path through the heart
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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.
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
aortacarotid = to head
to brain & left arm
to right arm
pulmonary
artery
coronary
arteries
to body
pulmonar
y
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
The heart contracts and relaxes
rhythmically
 Diastole
 Blood flows from
the veins into the
heart chambers
 Systole
 The atria briefly
contract and fill the
ventricles with
blood
 Then the ventricles
contract and propel
blood out
The pacemaker sets the tempo of
the heartbeat
 The SA node (pacemaker) generates
electrical signals that trigger the
contraction of the atria
 The AV node then relays these signals to
the ventricles
heart pumping controlled by electrical
impulses
signal also transmitted to skin = EKG
electrocardiogram
Connection: What is a heart
attack?
 A heart attack is damage that occurs when
a coronary feeding the heart is blocked
Right
coronary
artery
Aorta
Left
coronary
artery
Blockage
Dead muscle
tissue
Cardiovascular diseases are the leading
cause of death in the United States
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Blood vessel blockage is usually due to blood clots
Atherosclerosis: Growths called plaques develop in the inner
wall of the arteries, narrowing their bore
In some cases, plaques also become hardened by calcium
deposits, leading to arteriosclerosis, commonly known as
hardening of the arteries
Connective
tissue
Smooth
Epithelium
muscle
Plaque
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.
Blood exerts pressure on vessel
walls
 Blood pressure
depends on
 cardiac output
 resistance of
vessels
 Pressure is highest
in the arteries
 It drops to zero by
the time the blood
reaches the veins
Systolic
pressure
Diastolic
pressure
Relative
sizes and
numbers
of blood
vessels
Three factors keep blood moving back
to the heart
 muscle contractions
 breathing
 one-way valves
Connection: Measuring blood pressure
can reveal cardiovascular problems
 Blood pressure is measured as systolic and diastolic
pressures
 Hypertension is persistent systolic pressure higher
than 140 mm Hg and/or diastolic pressure higher
than 90 mm Hg
 It is a serious cardiovascular problem
STRUCTURE AND FUNCTION OF BLOOD
 Blood consists of cells suspended in plasma
 Plasma is an aqueous solution of various
substances
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
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
Red blood cells
 transport oxygen
 Small round cells
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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
Hemoglobin
 Protein which carries O2
 250,000 hemoglobins in 1 red blood
cell
O2
O2
O2
O2
White blood cells help defend the
body
 White blood cells
(leukocytes)
 function both
inside and outside
the circulatory
system
 They fight
infections and
cancer
Blood clots plug leaks when blood
vessels are injured
 When a blood
vessel is damaged,
platelets respond
 They help trigger
the formation of an
insoluble fibrin clot
that plugs the leak
Connection: Stem cells offer a potential
cure for leukemia and other blood cell
diseases
 All blood cells
develop from stem
cells in bone
marrow
 Such cells may
prove valuable for
treating certain
blood disorders
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