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Circulatory and
Respiratory
System
Circulatory System
Heart Anatomy
Heart Location
Fun Fact
• If all arteries, veins, and capillaries of the human
circulatory system were laid end to end, the total
length would be 60,000 miles. That's nearly 2 ½
times around the Earth!
• Your body has about 5.6 liters and circulates
through the body 3 times/min. In one day, the
blood travels a total of 12,000 miles- that's four
times the distance across the U.S. from coast to
coast.
Circulatory System
• Structures:
o Heart, Blood vessels, blood
• Functions:
o Brings oxygen, nutrients and hormones
to cells
o Fights infection
o Regulates body temperature.
Heart
• Made of cardiac
muscle
• Beats on average 6585 beats per minute
• Pumps to circulate
blood throughout the
body
Take your Pulse
Locating Pulse Points :The pulse is actually
the arteries expanding in rhythm with the
contraction of the heart. The pulse can
be taken at a variety of locations on the
body.
There are seven common pulse points
• Radial pulse (thumb side of the wrist)
• Brachial pulse (inner elbow)
• Carotid pulse (neck)
• Popliteal pulse (behind the knee)
• Posterior tibial pulse (behind the ankle
bone)
• Dorsalis pedis pulse (top of the foot)
Blood Vessels:
•
•
•
Carry blood to cells
Lined with smooth muscle tissue and
epithelial cells
Simplest and most common route:
Heart  arteries  arterioles  capillaries 
venules  veins
Arteries (carries blood away from heart)
• Carry oxygenated blood from the heart to the rest of
the body.
• Strong, thick, elastic walls adapted for high pressure
• Arteries become smaller as they divide and give rise to
arterioles.
Arteries
• Arteries are capable of vasoconstriction as
directed by the sympathetic impulses; when
impulses are inhibited, vasodilation results; used
to regulate blood flow and blood pressure.
• Walls of arterioles get thinner as they approach
the capillaries.
Fig 13.17
12
Aspirin
Aneurysm
• Aneurysm—weak point in
an artery or the heart wall
o Forms a thin-walled, bulging
sac that pulsates with each
heartbeat and may rupture
o Dissecting aneurysm: blood
accumulates between the
tunics of the artery and
separates them
o Most common sites:
abdominal aorta, renal
arteries, and arterial circle
at base of brain
20-14
Aneurysm
• Aneurysm (cont.)
o Can cause pain by putting pressure on other structures
o Can rupture causing hemorrhage
o Result from congenital weakness of the blood vessels
or result of trauma or bacterial infections such as
syphilis
• Most common cause is atherosclerosis and
hypertension
20-15
Arterial
stent
Capillaries
• Branch off of the Arterioles
• The smallest of the blood vessels
o some have diameters as small as 1 red blood cell
• Takes blood to cells where
nutrients/gases exchanged
Fig 13.19
18
Capillaries
o Capillary permeability varies from one tissue to the
next (generally with more permeability in the liver,
intestines, and certain glands, and less in muscle)
o Areas with a great deal of metabolic activity (leg
muscles, for example) have higher densities of
capillaries.
o Precapillary sphincters can regulate the amount of
blood entering a capillary bed and are controlled by
oxygen concentration in the area; if blood is needed
elsewhere in the body, the capillary beds in less
important areas are shut down.
Fig 13.18
20
Capillary Beds
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Precapillary
sphincters
Thoroughfare
channel
Metarteriole
Capillaries
Arteriole
Venule
Figure 20.3a
(a) Sphincters open
When sphincters are open, the capillaries are well
perfused and engage in exchanges with the tissue
20-21
fluid
Capillary Beds
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Figure 20.3b
Arteriole
(b) Sphincters closed
Venule
• When the sphincters are closed, little to no blood flow
occurs (skeletal muscles at rest)
• ¾ of body’s capillaries are shut down at a given20-22
time
Exchange in Capillaries
• Hydrostatic pressure drives the passage of fluids and
very small molecules out of the capillary at the arteriole
end by diffusion.
• At the venule end, osmosis, due to the osmotic pressure
of the blood, causes much of the tissue fluid to return to
the bloodstream.
• Lymphatic vessels collect excess tissue fluid and return it
to circulation.
Veins (and venules)
• Venules leading from capillaries merge to form veins
that return blood (deoxygenated) to the heart.
Veins
• Veins have the same three layers as
arteries have, except that the muscle
layer is thinner, and have a flap-like valve
inside to prevent backflow of blood.
• The lumen of a vein is larger than an
artery
• Veins do not carry high-pressure blood.
• Veins also function as blood reservoirs.
• Greater capacity for
blood containment
than arteries
• Thinner walls, flaccid,
less muscular and
elastic tissue
• Collapse when empty,
expand easily
• Have steady blood
flow
• Merge to form larger
veins
• Subjected to relatively
low blood pressure
o Remains 10 mm Hg
with little fluctuation
Veins
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Distribution of Blood
Pulmonary
circuit
18%
Veins
54%
Heart
12%
Systemic
circuit
70%
Arteries
11%
Capillaries
5%
Figure 20.8
20-26
Blood Flow Comparison
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
At rest
Total cardiac output 5 L/min
Moderate exercise
Total cardiac output 17.5 L/min
Other
Coronary 350 mL/min
200 mL/min
(7.0%)
(4.0%)
Cutaneous
300 mL/min
(6.0%)
Other
Coronary
400
mL/min
750 mL/min
(2.3%)
Cutaneous (4.3%)
1,900 mL/min
(10.9%)
Muscular
1,000 mL/min
(20.0%)
Cerebral
700 mL/min
(14.0%)
Renal
1,100 mL/min
(22.0%)
Cerebral
750 mL/min
(4.3%)
Digestive
1,350 mL/min
(27.0%)
• During exercise
Renal
600 mL/min
(3.4%)
Digestive
600 mL/min
(3.4%)
Muscular
12,500 mL/min
(71.4%)
Figure 20.15
o Increased perfusion of lungs, myocardium, and skeletal
muscles
o Decreased perfusion of kidneys and digestive tract 20-27
Fig 13.23
28
The Skeletal Muscle Pump
Muscles help pump blood back to heart through the veins
To heart
Valve open
Venous
blood
Valve closed
(a) Contracted skeletal muscles
(b) Relaxed skeletal muscles
Figure 20.19a,b
Copyright © The McGraw-Hill Companies, Inc. Permissio required for reproduction or display.
20-29
Comparing arteries and veins
Fig 13.20
34
Varicose veins
Varicose Veins
• Blood pools in the lower legs in people who stand
for long periods stretching the veins
o Cusps of the valves pull apart in enlarged superficial
veins further weakening vessels
o Blood backflows and further distends the vessels, their
walls grow weak and develop into varicose veins
• Hereditary weakness, obesity, and pregnancy
also promote problems
• Hemorrhoids are varicose veins of the anal
canal
Treatment for
varicose/spider veins
• Sclerotherapy.
doctor injects the veins
with a solution that
scars and closes those
veins, causing the
blood to reroute
through healthier veins.
• Vein ligation/vein
striping
• Laser surgery. Laser
surgery works by sending
strong bursts of light into
the vein that make the
vein slowly fade and
disappear. No incisions
or needles are used. The
treatment is often less
effective than
sclerotherapy.
Fig 13.1
39
The Heart
• The human heart has four chambers
oLeft and right atrium (above)
oLeft and right Ventricles (make a V)
• The right side of the heart pumps
deoxygenated blood to the lungs
• The left side of the heart pumps
oxygenated blood to the body
Left Atrium
Right Atrium
Right Ventricle
Left Ventricle
Fig 13.4
43
Upper body
Blood
Flow in
the Heart
Cool Facts about the circulatory system
Valves of the Heart
Operation of the Heart Valves
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Atrium
Atrioventricular
valve
Ventricle
Atrioventricular valves open
Atrioventricular valves closed
(a)
Figure 19.19
Aorta
Pulmonary
artery
Semilunar
valve
Semilunar valves open
(b)
Semilunar valves closed
19-49
Fig 13.6
50
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
The Valves
Left AV
(bicuspid) valve
Right AV
(tricuspid) valve
Fibrous
skeleton
Openings to
coronary arteries
Aortic
valve
Pulmonary
valve
(a)
Figure 19.8a
19-51
The Valves: Endoscopic View
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(b)
© Manfred Kage/Peter Arnold, Inc.
Figure 19.8b
19-52
Heart Sounds
• Heart sounds are due to vibrations in heart tissues
as the valves close.
• Heart sounds can be described as a "lubb-dupp"
sound.
o The first sound (lubb) occurs as ventricles contract and
AV valves are closing.
o The second sound (dupp) occurs as ventricles relax
and aortic and pulmonary valves are closing.
• An abnormal heart sound is called a murmur which
is due to valve damage.
53
Heart Murmurs
• Aortic Valve Replacement
Fig 13.8
55
Coronary Arteries
Intraventricular Septum
1) The right atrium receives deoxygenated blood
from the body through the superior and inferior
vena cava.
2) The right atrium pumps blood through
the tricuspid (AV) valve and into the right
ventricle
3) Right Ventricle Contracts and pushes blood
through pulmonary valve towards lungs
4) Blood is pushed through the pulmonary
arteries to the lungs to receive oxygen
5) Oxygenated blood returns to the left
atrium from the lungs through the
pulmonary veins
6) Blood passes through the bicuspid
(mitral) valve into the left ventricle.
7) Contraction of Left ventricle pumps
blood through aortic valve to the aorta
8)Blood travels through aorta and then to all regions of
the body where it feeds cells with oxygen picked up
from the lungs and nutrients from the digestive tract.
Blood Pressure
• A measure of the force exerted by the
blood on the wall of the arteries.
(using sphygmomanometer)
o An example is 120/80 (systolic
pressure/diastolic pressure.
• Systolic pressure is the result of the
contraction of the ventricles (normal 110140)
• Diastolic pressure is during the ventricle
relaxation (normal 70-90)
o Pressure decreases as distance from the
left ventricle increases.
Blood Pressure
• Hypertension—high blood pressure
o Chronic is resting BP > 140/90
o Consequences
• Can weaken small arteries and cause aneurysms
• atherosclerosis
• Hypotension—chronic low resting BP
o Caused by blood loss, dehydration, anemia
20-68
Blood Pressure
• BP rises with age
o Arteries less distensible and absorb less
systolic force
• BP determined by cardiac output, blood
volume, and peripheral resistance
o Resistance hinges on blood viscosity, vessel
length, and vessel radius
20-69
Cardiac output
• Cardiac output = stroke volume x
heart rate.
• Stroke volume is the amount of blood
discharged from the ventricles with a
contraction (about 70 mL).
• Heart rate is the beats per minute
(average is 72 beats/min).
Peripheral Resistance
• Peripheral resistance—the opposition to
flow that blood encounters in vessels away
from the heart
• Resistance hinges on three variables
1. Blood viscosity (“thickness”)
• RBC count and albumin concentration elevate
viscosity the most
• Decreased viscosity with anemia
• Increased viscosity with dehydration
20-71
Peripheral Resistance
• Resistance hinges on three variables (cont.)
2. Vessel length
• The farther liquid travels through a tube, the
more cumulative friction it encounters
• Pressure and flow decline with distance
o Vessel radius: most powerful influence over flow
• Vasomotion—change in vessel radius
oVasoconstriction: increases
resistance=increases bp
oVasodilation: by relaxation of the smooth
muscle, decreases resistance=decreased
pressure
20-72
Fig 13.24
73
Peripheral Resistance
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(a)
(b)
Figure 20.11
20-74
Blood Volume
• Blood pressure is normally directly
proportional to the volume of blood
within the cardiovascular system.
• Blood volume varies with age, body
size, and gender.
Fig 13.25
76
Control of Blood Pressure
1.Blood pressure is determined by cardiac
output times peripheral resistance; BP =
CO x PR
1.The body maintains normal blood pressure
by adjusting cardiac output and peripheral
resistance.
77
Control of Blood Pressure
• Frank-Starling law of the heart is the
relationship between fiber length and force
of contraction.
a. As blood enters the heart, the walls are
stretched, giving a stronger contraction.
b. The stronger contraction increases stroke
volume and cardiac output.
78
Control of Blood Pressure
• Baroreceptors sense change in BP
a. The volume of blood that enters the right
atrium is normally equal to the volume
leaving the left ventricle.
b. If arterial pressure increases, the cardiac
center of the medulla oblongata sends
parasympathetic impulses to slow heart rate
(cardioinhibitor reflex).
c. If arterial pressure drops, the medulla
oblongata sends sympathetic impulses to
increase heart rate to adjust blood pressure
(cardioaccelerator reflex).
79
Baroreceptors
80
Fig 13.26
81
Control of Blood Pressure
• Other factors, such as emotional upset,
exercise, and a rise in temperature can result
in increased cardiac output and increased
blood pressure.
• Peripheral resistance also controls blood
pressure
a. Sympathetic nerves change the diameter of
arterioles in response to blood pressure
changes.
b. Vasodilation will decrease PR and BP.
c. Vasoconstriction will increase PR and BP.
82
Control of Blood Pressure
• The vasomotor center of the medulla
oblongata can adjust the sympathetic
impulses to smooth muscles in arteriole
walls, adjusting blood pressure.
• Certain chemicals can also affect peripheral
resistance by affecting precapillary
sphincters and smooth muscle of arteriole
walls.
a. Increased CO2, decreased O2, and decreased
pH cause vasodilation into tissues with high
metabolic needs.
b. Epinephrine and norepinephrine cause
vasoconstriction.
83
Hormonal Control of Blood Pressure
• Hormones influence blood pressure
o Some through their vasoactive effects
o Some by regulating water balance
• Angiotensin II—potent vasoconstrictor
o Raises blood pressure
o Promotes Na+ and water retention by kidneys
o Increases blood volume and pressure
• Atrial natriuretic peptide—increases urinary
sodium excretion
o Reduces blood volume and promotes vasodilation
o Lowers blood pressure
20-84
Hormonal Control of Blood Pressure
• ADH promotes water retention and raises BP
o Pathologically high concentrations; also a
vasoconstrictor
• Epinephrine and norepinephrine effects
o Most blood vessels
• Bind to -adrenergic receptors—vasoconstriction
o Skeletal and cardiac muscle blood vessels
• Bind to -adrenergic receptors—vasodilation
20-85
Disorders of the Circulatory System:
Coronary artery disease –
Atherosclerosis
• Plaque buildup
blocks arteries,
reducing, or even
stopping blood
flow
• Plaques can break
off, causing heart
attack or stroke
Coronary Artery disease
Cause: Damaged arteries are ‘invaded’ by
bad LDL cholesterol. White blood cells try to
digest the LDL. Ultimately, a jumble of
cholesterol and whilte blood cells is
accumulated.
Risk Factors: Smoking, high blood pressure,
high LDL cholesterol, diabetes
Treatments
• Lifestyle changes: Follow healthy diet, maintain
healthy weight, exercise, quit smoking, manage
stress
• Medicine: lowers cholesterol, helps prevent
platelets from sticking and clotting (aspirin),
helps harden plaque so lowers chance of
breaking off
• Surgeries:
o Angioplasty (Coronary Stent)
o Coronary artery bypass
o Carotoid endartectomy
Coronary Bipass Surgery
The Cardiac Conduction System
1 SA node fires.
Right atrium
2 Excitation spreads through
atrial myocardium.
2
1
Sinoatrial node
(pacemaker)
Left
atrium
2
Atrioventricular
node
Atrioventricular
bundle
Purkinje
fibers
3
Bundle
branches
4
5
3 AV node fires.
4 Excitation spreads down AV
bundle.
5 Purkinje fibers distribute
excitation through
ventricular myocardium.
Purkinje fibers
Figure 19.12
19-92
Cardiac Conduction System
1.Specialized cardiac muscle tissue conducts
impulses throughout the myocardium and
comprises the cardiac conduction system.
2.A self-exciting mass of specialized cardiac
muscle called the sinoatrial node (SA node or
pacemaker), located on the posterior right
atrium, generates the impulses for the
heartbeat.
93
Fig 13.11
94
Pacemaker Physiology
• SA node does not have a stable resting
membrane potential
o Starts at −60 mV and drifts upward from a
slow inflow of Na+
• When it reaches threshold of −40 mV,
voltage-gated fast Ca2+ and Na+ channels
open
o Faster depolarization occurs peaking at 0 mV
o K+ channels then open and K+ leaves the cell
• Causing repolarization
• Once K+ channels close, pacemaker potential
starts over
19-95
Pacemaker Physiology
• Each depolarization of the SA node
sets off one heartbeat
o At rest, fires every 0.8 second or 75
bpm
• SA node is the system’s pacemaker
19-96
Pacemaker Physiology
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Membrane potential (mV)
+10
0
–10
Fast K+
outflow
Fast
Ca2+–Na+
inflow
–20
Action
potential
Threshold
–30
–40
Pacemaker
potential
–50
–60
Slow Na+
inflow
–70
0
.4
.8
1.2
1.6
Time (sec)
Figure 19.13
19-97
Cardiac Conduction System
3.Impulses spread next to the atrial
syncytium, it contracts, and impulses
travel to the junctional fibers leading to
the atrioventricular node (AV node) located
in the septum.
a. Junctional fibers are small, allowing the atria
to contract before the impulse spreads
rapidly over the ventricles.
b. The delay through these fibers allows both
atria to contract together.
98
Cardiac Conduction System
4.From the AV node, the impulse passes to
branches of the AV bundle and travel down the
interventricular septum.
5.Purkinje fibers branch off the bundle branches
and lead into the ventricular wall and papillary
muscles.
6.These fibers stimulate contraction of the papillary
muscles at the same time as the ventricles
contract in a twisting, upward motion.
99
Fig 13.11
10
0
Fig 13.12
10
1
Fig 13.13
10
2
Electrocardiogram (ECG)
Electrocardiogram (ECG)
Electrocardiogram
1.An electrocardiogram (ECG) is a recording of
the electrical changes that occur during a
cardiac cycle.
2.The first wave, the P wave, corresponds to
the depolarization of the atria which leads to
the contraction of the atria.
3.The QRS complex corresponds to the
depolarization of ventricles that leads to
contraction of the ventricles and hides the
repolarization of atria.
10
6
Electrocardiogram
4.The T waves ends the ECG pattern and
corresponds to ventricular repolarization
and relaxation.
5.The intervals between the waves as well
as the size of the waves give information
about the heart’s ability to conduct
impulses.
10
8
Fig 13.14
10
9
Fig 13.15
11
0
Electrocardiogram
1. The amount of blood pumped at any one time
must adjust to the current needs of the body
(more is needed during strenuous exercise).
2. The SA node, AV node, and the myocardium are
innervated by branches of the sympathetic and
parasympathetic divisions of the autonomic
nervous system.
a. Sympathetic impulses increase the speed
and strength of heart contractions.
b. Heart rate is decreased by parasympathetic
impulses.
11
1
Regulation of the cardiac cycle
3.The cardiac control center of the medulla
oblongata maintains a balance between the
sympathetic and parasympathetic divisions of
the nervous system in response to messages
from baroreceptors which detect changes in
blood pressure.
4.Impulses from the cerebrum or hypothalamus
may also influence heart rate through emotions.
5.Increased body temperature will increase heart
rate.
11
2
Regulation of the cardiac cycle
6.Hyperkalemia (excess K+) will decrease rate
and force of contraction; hypokalemia may
cause life-threatening arrhythmias.
7.Hypercalcemia (excess Ca2+) increases
heart action while hypocalcemia depresses
heart action.
8.Tachycardia – more that 100 beats/min
9.Bradycardia – less than 60 beats/min
11
3
Fig 13.16
11
4
Disorders of the Circulatory System
• Arrhythmia= Irregular / skipped heart beat
Cause: The heart uses electrical signals created
in the SA node in the right atria, to begin a
heartbeat. The conduction of these signals, or
irregular firing of the SA node, can cause
arrhythmias. Atrial arrhythmias are less
dangerous than ventricular arrhythmias.
Risk Factors: Generally random, but factors are
stimulants (such as caffeine), fevers, stress, or
genetic disorders.
AFIB Oblation
Disorders of the Circulatory System
• High blood pressure - Hypertension
Diastolic pressure over 90
Why it is dangerous: Excessive pressure can
cause the arteries to thicken, and blood vessels
to weaken and rupture. This can lead to heart
failure, stroke, kidney failure, loss of sight when
vessels in eyes burst.
Risk Factors: Genetics, overweight, limited
physical activity, smoking, alcohol
consumption, certain medications
Virtual Cardiology Lab
Disorders of the Circulatory System
• Heart Attack– Myocardial Infarction (MI)
= Death of cardiac muscle cells
Cause: Plaque dislodges, blocking an artery to
the heart muscle. Cardiac muscle cells are
starved for oxygen and die. After, scar tissue
forms where cells died, reducing function of
heart. Severity of a heart attack depends on size
and area supplied by the artery.
Risk Factors: Smoking, high blood pressure, high
LDL cholesterol, diabetes
Bypass surgery
Disorders of the Circulatory System
• Stroke=Death of cells in the brain.
Cause: A blood vessel in the brain is blocked
(by dislodged plaque, or bursts, starving the
cells of oxygen)
A stroke can have many different symptoms,
including: numbness, vision changes, speech
changes, or confusion.
Risk Factors: Smoking, high blood pressure, high
LDL cholesterol, diabetes