Download Cardiovascular System

Cardiovascular System
The Heart and Vessels
Function of the Cardiovascular
System
 the delivery of oxygen, nutrient
molecules, and hormones to the
tissues
 removal of carbon dioxide, ammonia
and other metabolic wastes.
Components of the circulatory
system include
 heart: a muscular pump to move the
blood
 blood vessels: arteries, capillaries and
veins that deliver blood to all tissues
 blood: a connective tissue of liquid
plasma and cells
 http://www.getbodysmart.com/ap/cir
culatory/menu/circulatory.html
A pump for all seasons
THE HEART
The Heart
 composed of cardiac muscle.
 adjusts the rate of muscular
contraction, allowing the heart to
maintain a regular pumping rhythm.
 The main parts of the heart are the
chambers, the valves, and the
electrical nodes.
Heart Chambers
 two types
 atrium (plural is atria), receives blood
returning to the heart through the veins.
 The right atrium pumps blood to the right
ventricle, and the left atrium pumps blood into
the left ventricle.
 ventricles - much larger than the atria and
their thick, muscular walls are used to
forcefully pump the blood from the heart to
the body and lungs (or gills).
Valves
 found within the heart between the atria
and ventricles, and between the ventricles
and major arteries.
 opened and closed by pressure changes
within the chambers, and act as a barrier to
prevent the backflow of blood.
 The characteristic "lub-dub, lub-dub" heart
sounds heard through a stethoscope are
the result of vibrations caused by the
closing of the respective valves.
Two different electrical nodes, or groups of
specialized cells, located in the cardiac
tissue.
ELECTRICAL NODES
Sinoatrial (SA) node
 Commonly called the pacemaker which
controls the heart beat.
 embedded in the wall of the right atrium,
 composed of muscle tissue that sends
electrical impulses to the rest of both atria
to contract. The impulse then spreads to the
ventricles, causing them to contract.
atrioventricular (AV) node
 relays the impulse of the SA node to the
ventricles.
 It delays the impulse to prevent the
ventricles from contracting at the same
time as the atria, thus giving them time to
fill with blood.
 The cycle of contraction of the heart
muscle is called a heartbeat
 the rate varies greatly between organisms.
The heart cycle involves three phases:
HEARTBEATS
Phase one
 The atria contract and force blood into the
ventricles.
 If the atria don’t contract, this is called atrial
fibrillation and pooled blood in the atria can
begin to clot.
 When the atria start beating normally again,
these clots may be sent throughout the person’s
system.
 If one of these clots lodges in an arteriole
somewhere, it could cause a stroke, heart attack, or
similar problem.
 As blood is pushed into the ventricles, when
the A-V valves close, the ventricular walls
vibrate a little causing the first sound of the
heart beat, the “lubb” sound.
Phase two
 The ventricles contract and force blood into the
arteries.
 This is called systole and the systolic blood pressure
(BP) is the higher of the two numbers, when the heart
is actively contracting and putting pressure on the
blood.
 When the semilunar valves snap shut, this causes the
second sound of the heart beat, the “dup.”
Phase three
 The heart relaxes and blood flows into the atria
and ventricles.
 This is called diastole. The diastolic BP is the
lower of the two numbers, when the heart is
relaxed, and so, is a measure of how much
pressure the arteries, themselves, are putting
on the blood.
 Clogged arteries are less elastic, so the blood is
under more pressure, thus more likely to cause the
arteries to burst.
Heartbeats
 The contraction of
the heart and the
action of the nerve
nodes located on
the heart.
 Heartbeats are
coordinated
contractions of
heart cardiac cells,
shown.
 When two or more
of such cells are in
proximity to each
other their
contractions synch
up and they beat
as one.
Measuring the change
ELECTROCARDIOGRAM
Electrocardiogram
 (ECG) measures changes in electrical
potential across the heart, and can detect
the contraction pulses that pass over the
surface of the heart. ECGs are useful in
diagnosing heart abnormalities.
 There are three slow, negative changes,
known as P, R, and T.
 Positive deflections are the Q and S waves.
 The P wave represents the contraction impulse
of the atria, the T wave the ventricular
contraction.
 Normal cardiac
pattern (top) and
some abnormal
patterns (bottom).
average heart rates of some
common mammals.
 Heart Rates Comparison
(beats/minute)










Organism
Human
Cat
Cow
Dog
Guinea Pig
Hamster
Horse
Rabbit
Rat
Average RateNormal Range
70
65
115
280
450
44
205
120
328
58 – 104
110 – 140
60 – 70
100 – 130
260 – 400
300 – 600
23 – 70
123 – 304
261 - 600
The Vascular System
 Two main routes for circulation:
 the pulmonary (to and from the lungs)
 the systemic (to and from the body).
 Pulmonary arteries carry blood from the heart
to the lungs.
 In the lungs gas exchange occurs.
 Pulmonary veins carry blood from lungs to
heart.
 The aorta is the main artery of systemic circuit.
 The vena cavae are the main veins of the
systemic circuit.





Coronary arteries deliver oxygenated blood, food, etc.
to the heart.
Animals often have a portal system, which begins and
ends in capillaries, such as between the digestive tract
and the liver.
Fish pump blood from the heart to their gills, where gas
exchange occurs, and then on to the rest of the body.
Mammals pump blood to the lungs for gas exchange,
then back to the heart for pumping out to the systemic
circulation.
Blood flows in only one direction.
A vessel is a hollow tube for transporting something, like a
garden hose transporting water.
VESSELS
Vessels
 A blood vessel is a hollow tube for
transporting blood. There are three main
types of blood vessels:
 Arteries
 Capillaries
 Veins
 These main blood vessels function to
transport blood through the entire body and
exchange oxygen and nutrients for carbon
dioxide and wastes.
Arteries
 The arteries carry blood away from the
heart, and are under high pressure from
the pumping of the heart.
 To maintain their structure under this
pressure, they have thick, elastic walls to
allow stretch and recoil.
 The large pulmonary artery
carries unoxygenated blood from
the right ventricles to the lung,
where it gives off carbon dioxide
and receives oxygen.
 The aorta is the largest artery. It
carries oxygenated blood from the
left ventricle to the body. The
arteries branch and eventually lead
to capillary beds.
Structure of an artery
 The aorta is the main artery leaving the
heart.
 The pulmonary artery is the only artery
that carries oxygen-poor blood.
 carries deoxygenated blood to the lungs.
 In the lungs, gas exchange occurs, carbon
dioxide diffuses out, oxygen diffuses in.
 Arterioles are small arteries that connect larger
arteries with capillaries.

Small arterioles branch into collections of capillaries known
as capillary beds,
 Cardiac muscle cells are serviced by a system of
coronary arteries. During exercise the flow through
these arteries is up to five times normal flow.
 Blocked flow in coronary arteries can result in death
of heart muscle, leading to a heart attack.
 Blockage of coronary arteries, is usually the result of
gradual buildup of lipids and cholesterol in the inner
wall of the coronary artery.
 Angina indicates oxygen demands are greater than
capacity to deliver it and that a heart attack may
occur in the future.
 Heart muscle cells that die are not replaced since
heart muscle cells do not divide.
Development of arterial plaque.
Capillaries
 capillaries make up a
network of tiny vessels
with extremely thin,
highly permeable walls.
They are present in all of
the major tissues of the
body.
 Capillaries are the points
of exchange between the
blood and surrounding
tissues.
 Materials cross in and
out of the capillaries by
passing through or
between the cells that
line the capillary
 In the capillary, the wall is only one cell layer thick.
 Capillaries are concentrated into capillary beds. Some
capillaries have small pores between the cells of the
capillary wall, allowing materials to flow in and out of
capillaries as well as the passage of white blood cells.
 Nutrients, wastes, gases, and hormones are
exchanged across the thin walls of capillaries.
 Capillaries are microscopic in size, although blushing
is one manifestation of blood flow into capillaries.
 Control of blood flow into capillary beds is done by
nerve-controlled sphincters.
 Changes in blood
pressure also occur
in the various
vessels of the
circulatory system.
Capillary structure, and
relationships of capillaries to
arteries and veins.
Capillary beds and their feeder
vessels
 Blood leaving the capillary beds flows into a
progressively larger series of venules that in
turn join to form veins.
 Venules are smaller veins that gather blood
from capillary beds into veins.
Veins
 At the opposite side of the capillary beds, the capillaries
merge to form veins, which return the blood back to the
heart.
 The veins are under much less pressure than the arteries
and therefore have much thinner walls.
 The veins also contain one-way valves in order to
prevent the blood from flowing the wrong direction in the
absence of pressure.
 The pulmonary vein returns oxygenated blood from the
lungs to the left atria.
 The vena cava returns blood from the body to the right
atria. The blood that is returned to the heart is then
recycled through the cardiovascular system.
Structure of a vein
 the actions of
muscles to propel
blood through the
veins.
Types of systems
There are several types of circulatory
systems
Circulatory systems of an insect
and mollusk.




The open circulatory system,
examples of which are
diagrammed, is common to
mollusks and arthropods.
Open circulatory systems
(evolved in insects, mollusks
and other invertebrates)
pump blood into a hemocoel
with the blood diffusing back
to the circulatory system
between cells.
Blood is pumped by a heart
into the body cavities, where
tissues are surrounded by the
blood.
The resulting blood flow is
sluggish.

insect (top) and mollusk
(bottom).
closed circulatory system







Vertebrates, and a few invertebrates, have a closed
circulatory system.
Closed circulatory systems (evolved in echinoderms and
vertebrates) have the blood closed at all times within
vessels of different size and wall thickness.
In this type of system, blood is pumped by a heart through
vessels, and does not normally fill body cavities.
Blood flow is not sluggish.
Hemoglobin causes vertebrate blood to turn red in the
presence of oxygen; but more importantly hemoglobin
molecules in blood cells transport oxygen.
The human closed circulatory system is sometimes called
the cardiovascular system.
A secondary circulatory system, the lymphatic circulation,
collects fluid and cells and returns them to the
cardiovascular system.
Mammals
Mammals and Birds
 Mammalian and avian hearts have four
chambers – two atria and two ventricles.
 This is the most efficient system, as
deoxygenated and oxygenated bloods are
not mixed.
 The right atrium receives deoxygenated
blood from the body through both the
inferior and superior vena cava.
 The blood then passes to the right ventricle
to be pumped through the pulmonary
arteries to the lungs, where it becomes
oxygenated.
 It returns to the left atrium via the pulmonary veins,
this oxygen-rich blood is then passed to the left
ventricle and pumped through the aorta to the rest of
the body.
 The aorta is the largest artery and has an enormous
amount of stretch and elasticity to withstand the
pressure created by the pumping ventricle.
 The four-chambered heart ensures that the tissues of
the body are supplied with oxygen-saturated blood to
facilitate sustained muscle movement.
 Also, the larger oxygen supply allows these warmblooded organisms to achieve thermoregulation
(body temperature maintenance).
Mammal and Bird
 Blood flow through
the closed system
Amphibians and Reptiles
 Amphibians and reptiles have a three-chambered heart.
 Consists of two atria and one ventricle.
 Blood leaving the ventricle passes into one of two
vessels.
 It travels through the pulmonary arteries leading to
the lungs or through a forked aorta leading to the
rest of the body.
 Oxygenated blood returning to the heart from the lungs
through the pulmonary vein passes into the left atrium,
while deoxygenated blood returning from the body
through the sinus venosus passes into the right atrium.
Both atria empty into the single ventricle, mixing the
oxygen-rich blood returning from the lungs with the
oxygen-depleted blood from the body tissues.
Amphibians and Reptiles
 While this system assures that some
blood always passes to the lungs and
then back to the heart, the mixing of
blood in the single ventricle means the
organs are not getting blood saturated
with oxygen. This is not as efficient as a
four-chambered system, which keeps
the two circuits separate, but it is
sufficient for these cold-blooded
organisms.
 The heart rate of amphibians and
reptiles is very dependent upon
temperature.
Amphibian
 Blood flow through
the system
Reptile
 Blood flow through
the system
Vitals
 Temperature Average Rate
(Celsius)
(beats/minute)
 10 C
1–8
 18 C
15 – 20
 28 C
24 – 40
 >40 C
Irreversible cardiac
damage
Fish Heart
 Fish possess the
simplest type of
true heart – a
two-chambered
organ composed
of one atrium and
one ventricle.
 A rudimentary
valve is located
between the two
chambers.
 Blood is pumped
from the ventricle
through the
conus arteriosus
to the gills. The
conus arteriosus
is like the aorta in
other species.
Fish
 At the gills, the blood receives oxygen and gets
rid of carbon dioxide. Blood then moves on to
the organs of the body, where nutrients, gases,
and wastes are exchanged.
 There is no division of the circulation between
the gills and the body. That is, the blood
travels from the heart to the gills, and then
directly to the body before returning to the
atrium through the sinus venosus to be
circulated again.
 The heart rates of fish fall within the wide
range of 60-240 beats per minute, depending
upon species and water temperature. The fish's
heart rate will be slower at lower
temperatures.
What makes up blood?
BLOOD
PLASMA
 the liquid component of the blood.
 Mammalian blood consists of a liquid (plasma) and a
number of cellular and cell fragment components.
 Plasma is about 60 % of a volume of blood; cells and
fragments are 40%.
 Plasma has 90% water and 10% dissolved materials
including proteins, glucose, ions, hormones, and
gases. It acts as a buffer, maintaining pH near 7.4.
 Plasma contains nutrients, wastes, salts, proteins, etc.
Proteins in the blood aid in transport of large
molecules such as cholesterol.
RED BLOOD CELLS





also known as erythrocytes, are flattened, doubly concave
cells about 7 µm in diameter that carry oxygen associated
in the cell's hemoglobin.
Mature erythrocytes lack a nucleus. They are small, 4 to 6
million cells per cubic millimeter of blood, and have 200
million hemoglobin molecules per cell. Humans have a total
of 25 trillion red blood cells (about 1/3 of all the cells in the
body).
Red blood cells are continuously manufactured in red
marrow of long bones, ribs, skull, and vertebrae.
Life-span of an erythrocyte is only 120 days, after which
they are destroyed in liver and spleen. Iron from
hemoglobin is recovered and reused by red marrow. The
liver degrades the heme units and secretes them as
pigment in the bile, responsible for the color of feces.
Each second two million red blood cells are produced to
replace those thus taken out of circulation.
 Human Red Blood Cells, Platelets and Tlymphocyte (erythocytes = red; platelets =
yellow; T-lymphocyte = light green)
WHITE BLOOD CELLS





also known as leukocytes, are larger than erythrocytes, have a
nucleus, and lack hemoglobin.
They function in the cellular immune response.
White blood cells (leukocytes) are less than 1% of the blood's
volume.
They are made from stem cells in bone marrow.
There are five types of leukocytes, important components of the
immune system.





Neutrophils enter the tissue fluid by squeezing through capillary walls
and phagocytozing foreign substances.
Macrophages release white blood cell growth factors, causing a
population increase for white blood cells.
Lymphocytes fight infection.
T-cells attack cells containing viruses.
B-cells produce antibodies. Antigen-antibody complexes are
phagocytized by a macrophage. White blood cells can squeeze through
pores in the capillaries and fight infectious diseases in interstitial areas
The formation and actions of blood
clots.
Blood Clot Formation (blood cells,
platelets, fibrin clot)
The Lymphatic System



Water and plasma are forced from the capillaries into
intracellular spaces. This interstitial fluid transports
materials between cells. Most of this fluid is collected in the
capillaries of a secondary circulatory system, the lymphatic
system. Fluid in this system is known as lymph.
Lymph flows from small lymph capillaries into lymph
vessels that are similar to veins in having valves that
prevent backflow. Lymph vessels connect to lymph nodes,
lymph organs, or to the cardiovascular system at the
thoracic duct and right lymphatic duct.
Lymph nodes are small irregularly shaped masses through
which lymph vessels flow. Clusters of nodes occur in the
armpits, groin, and neck. Cells of the immune system line
channels through the nodes and attack bacteria and viruses
traveling in the lymph.
MONITORING THE
SYSTEM
 The rate of contraction is the heart
rate.
 The pulse is a wave of contraction of
the artery walls (which roughly
corresponds to the heart rate) as
blood is forced into the arteries. Pulse
is usually measured using the radial
artery (the one along the radius).
 Blood pressure is maximum during
systole, when the heart is pushing, and
minimum during diastole, when the heart is
relaxed.
 A sphygmomanometer is the instrument
used to determine BP. The artery used to
determine BP is the brachial artery, which
runs down the upper arm, splitting into the
radial and ulnar arteries near the elbow.
 The cuff of the
sphygmomanomet
er is wrapped
around the arm
just above the
elbow and pumped
up to block off
blood flow (the
pressure exerted
by the cuff is
higher than the
systolic pressure).
 The pressure in the
cuff is gradually
decreased, and
when it equals the
person’s systolic
pressure, the heart
can force blood
under the cuff, and
a sound is heard as
the pulses of blood
surge under the
cuff.
 As the pressure in
the cuff is lowered,
when it equals the
diastolic pressure,
blood can flow
freely, so the
sound disappears
(not enough
pressure is exerted
by cuff to restrict
blood flow).
 Thus, by listening for the first sound,
and when the sound becomes faint,
while watching the pressure indicator
on the sphygomomanometer, it is
possible to determine someone’s
blood pressure.
PROBLEMS
 A hemorrhage is bleeding, especially
profuse, and can be severe if internal.
 A hematoma is a local swelling or
tumor filled with blood; a bruise,
especially a large one. Sometimes, if
the injury is extensive, it can calcify
as it heals, leading to a hard lump
(which may need to be surgically
removed).
 A thrombus is a blood clot (platelets and
fibrin) which forms within a vessel and blocks
the blood flow.
 An embolus is a moving thrombus which may
“get stuck” somewhere. If thrombi or emboli
lodge in an artery supplying blood to the heart,
this can cause a coronary embolism or heart
attack or myocardial infarction. If one of
these becomes lodged in an artery in the
lungs, it is also a life-threatening pulmonary
embolism, and if in the brain, a cerebral (or
cerebellar) embolism or stroke or
cerebrovascular accident
 Edema is an accumulation of fluid
(plasma) within tissues and/or the
lymph system. There are many
possible causes of edema from injury,
to too much salt, to improperly
functioning kidneys, to lack of
exercise, to female hormonal
changes, to a number of other
possible causes.
 Much like a heat pump for your house or your
refrigerator coils, your cardiovascular system is also
involved in countercurrent heating/cooling of your
body. Arteries and veins lying near each other in your
extremities, but flowing in opposite directions can
absorb heat from each other as needed. When your
core temperature is too high, the arteries carry heat
to the extremities to be dissipated. As the blood
returns via the veins, any excess heat still in the
blood is transferred to the arterial blood and sent to
the extremities, again. When your core temperature is
too low, as the blood flows out in the arteries to
nourish the extremities, its heat is transferred to the
venous blood and sent back into the body to keep it
warm.