Transcript the cardiovascular system

THE CARDIOVASCULAR
SYSTEM
A closed circulatory system made up of
the heart, blood, and blood vessels
1. The heart pumps
blood
2. Blood vessels allow
blood to circulate to all
parts of the body
3. Blood is the fluid that
carries the substances
throughout the body
The function of the
cardiovascular system is to
deliver oxygen and nutrients
and to remove carbon dioxide
and other waste products
The Heart
• The heart is located in
the thorax between the
lungs
• The apex is pointed
toward the left hip
• The heart is about the
size of your fist
Chambers of the Heart
•Right and left side act as
separate pumps
•Four chambers:
Two atria act as receiving
chambers
Right atrium
Left atrium
•Two ventricles act as
discharging chambers
Right ventricle
Left ventricle
Valves
Allow blood to flow
in only one direction
Semilunar valves are between
ventricle and the arteries
Pulmonary (semilunar) valve
Aortic (semilunar) valve
Valves
The aortic valve shows three thin and delicate cusps. The
coronary artery openings can be seen just above. The
endocardium is smooth, beneath which can be seen a redbrown myocardium.
Atrioventricular valves are between atria and
ventricles
Bicuspid valve (left)
Tricuspid valve
(right)
Valves
This is the tricuspid valve. The leaflets and thin and
delicate. Just like the bicuspid valve, the leaflets have thin
chordae tendineae that attach the leaflet margins to the
muscles of the ventricular wall below.
• Valves open as
blood is pumped
through
• Held in place by
chordae tendineae
(“heart strings”)
• Close to prevent
backflow
The Heart’s Vessels
• Aorta
– Leaves left ventricle
• Pulmonary arteries
– Leave right ventricle
• Vena cava
– Enters right atrium
• Pulmonary veins (four)
– Enter left atrium
Stop ~
color the blood flow
through the heart.
Practice blood flow through the
heart
https://www.youtube.com/watch?v=T2iVqTc
kmPQ
Coronary Circulation
• Blood in the heart chambers does not nourish the
myocardium
• The heart has its own nourishing circulatory
system
• Coronary arteries
• Blood empties into the right atrium via the
coronary sinus
The Septum
• The wall that separates the right and left side
of the heart
Stop
Structure of the mammalian
heart
The Heart’s Conduction System
• Intrinsic conduction
system (nodal system)
– Heart muscle cells
contract, without nerve
impulses, in a regular,
continuous way
• Special tissue sets the
pace
• Contraction is initiated
by the sinoatrial node
(Pacemaker)
The Heart Cycle
Cardiac cycle – events of one complete heart beat
Mid-to-late diastole – blood flows into ventricles
Ventricular systole – blood pressure builds before ventricle contracts, pushing out blood
Early diastole – atria finish re-filling, ventricular pressure is low
The Heart Cycle
•
•
•
•
Atria contract simultaneously
Atria relax, then ventricles contract
Systole = Contraction of the ventricles
Diastole = Relaxation of the ventricles
The Cardiac Cycle
• Cardiac cycle – events of one complete heart
beat
o Mid-to-late diastole – blood flows into ventricles
o Ventricular systole – blood pressure builds
before ventricle contracts, pushing out blood
o Early diastole – atria finish re-filling, ventricle
pressure is low
BLOOD FLOW THROUGH THE
HEART
http://www.youtube.com/watch?v=NF68qhyfcoM&feature=related
http://www.youtube.com/watch?v=mH0QTWzU-xI
http://www.medmovie.com/mmdatabase/mediaplayer.aspx?Message=VG9waWNp
ZD03Njg7Q2xpZW50SUQ9NjU7VmVybmFjdWxhcklEPTE%3Dn3cYsAIEoB4%3D
http://www.youtube.com/watch?v=q0s-1MC1hcE&feature=related
Vocabulary
• Cardiac output (CO)
– Amount of blood pumped by each side of the
heart in one minute
– CO = (heart rate [HR]) x (stroke volume
[SV])
• Stroke volume [SV]
– Volume of blood pumped by each ventricle in
one contraction
• Heart Rate [HR]
– The number of beats per minute
• Stroke volume usually remains relatively
constant (in the short term)
• Starling’s law of the heart – the more that
the cardiac muscle is stretched, the
stronger the contraction (over the long
term)
However:
• Changing heart rate is the most common
way to change cardiac output during
exercise.
What increases the heart rate?
• Sympathetic nervous system
– Crisis
– Low blood pressure
• Hormones
– Epinephrine
– Thyroxin
• Exercise
• Decreased blood volume
What decreases the heart rate?
• Parasympathetic nervous system
• High blood pressure or blood volume
• Decreased venous return
Blood Vessels
• Taking blood to the tissues and back
– Arteries
– Arterioles
– Capillaries
– Venules
– Veins
Differences between blood vessel types
• Walls of arteries are the thickest
• Lumens of veins are larger
• Walls of capillaries are only one cell layer
thick to allow for exchanges between
blood and tissue
Movement of Blood Through Vessels
• Most arterial
blood is pumped
by the heart
• Veins use the
milking action of
muscles to help
move blood
True capillaries – exchange vessels
– Oxygen and nutrients cross to cells
– Carbon dioxide and metabolic waste products
cross into blood
Pulse
• Pulse –
pressure
wave of blood
• Monitored at
“pressure
points” where
pulse is
easily
palpated
Blood Pressure
• Measurements by health professionals are
made on the pressure in large arteries
• Systolic – pressure at the peak of
ventricular contraction
• Diastolic – pressure when ventricles relax
• Pressure in blood vessels decreases as the
distance away from the heart increases
Human normal range is variable
• Normal
– 140–110 mm Hg systolic
– 80–75 mm Hg diastolic
• Hypotension
– Low systolic (below 110 mm HG)
– Often associated with illness
• Hypertension
– High systolic (above 140 mm HG)
– Can be dangerous if it is chronic
Stop
Blood pressure/pulse lab
Blood
• The only fluid tissue in the human
body
• Classified as a connective tissue
–Living cells = formed elements
–Non-living matrix = plasma
Characteristics of blood
• Color range
– Oxygen-rich blood is scarlet red
– Oxygen-poor blood is dull red
• pH must remain between 7.35–7.45
• Blood temperature is slightly higher than
body temperature
Components of blood
•
•
•
•
Plasma
Erythrocytes (Red Blood cells)
Leukocytes (White blood cells)
Platelets
Plasma
• Composed of approximately 90
percent water
• Includes many dissolved
substances
–
–
–
–
–
–
Nutrients
Salts (metal ions)
Respiratory gases
Hormones
Waste products
Proteins
• Albumin – regulates osmotic
pressure
• Clotting proteins – help to stem
blood loss when a blood vessel is
injured
• Antibodies – help protect the body
from antigens
Formed Elements
• Erythrocytes = red blood cells
• Leukocytes = white blood cells
• Platelets = cell fragments
Erythrocytes = red blood cells
• The main function is to carry
oxygen
• Anatomy of circulating
erythrocytes
– Biconcave disks
– Essentially bags of hemoglobin
– Anucleate (no nucleus)
– Contain very few organelles
• RBC’s outnumber white blood
cells 1000:1
Hemoglobin
• Iron-containing protein
• Binds strongly, but reversibly, to oxygen
• Each hemoglobin molecule has four
oxygen binding sites
• Each erythrocyte has 250 million
hemoglobin molecules
Leukocytes (White blood cells)
• Crucial in the body’s defense
against disease
• These are complete cells, with a
nucleus and organelles
• Able to move into and out of blood
vessels (diapedesis)
• Can move by ameboid motion
• Can respond to chemicals released
by damaged tissues
• Leukocyte levels in the blood
• Normal levels are between 4,000
and 11,000 cells per mm3
• Leukocytosis
– Above 11,000 leukocytes/mm3
– Generally indicates an infection
• Leukopenia
– Abnormally low leukocyte level
– Commonly caused by certain drugs
Platelets
• Derived from ruptured multinucleate cells
(megakaryocytes)
• Needed for the clotting process
• Normal platelet count = 300,000/mm3
Blood clot formation
– Collagen fibers are exposed by a break in a blood
vessel
– Platelets become “sticky” and cling to fibers
– Anchored platelets release chemicals to attract more
platelets
– Platelets pile up to form a platelet plug
– Blood usually clots within 3 to 6 minutes
– The clot remains as endothelium regenerates
– The clot is broken down after tissue repair
Undesirable Blood Clots
– Thrombus
• A clot in an unbroken blood vessel
• Can be deadly in areas like the heart
– Embolus
• A thrombus that breaks away and floats freely in the
bloodstream
This section of coronary artery demonstrates a
thrombosis with recanalization leaving only two
small, narrow channels.
CARDIOVASCULAR DISORDERS
High Blood Pressure
• greater than or equal to 140 mm Hg
systolic pressure or
• greater than or equal to 90 mm Hg
diastolic pressure.
• Some people experience high blood
pressure only when they visit the doctor's
office. This condition is called "white-coat
hypertension."
Angina
• Angina (angina pectoris) is a type of
temporary chest pain, pressure or
discomfort that occurs when the heart
is not getting enough oxygen.
• The most common underlying cause
of angina is coronary disease artery,
which occurs when the coronary
arteries that supply the heart with
oxygen–rich blood become blocked
with plaque deposits
Stable vs. Unstable Angina
• If the angina occurs in predictable situations,
such as during exertion or exercise, it is known
as stable angina
• If the painful episodes occur without warning,
last longer than normal angina episodes and
occurs more frequently, it is known as unstable
angina. This is a dangerous medical situation
that requires prompt medical attention. Unstable
angina may signal that a heart attack is
impending.
Heart Attack
A heart attack is an event that results in
permanent heart damage or death. It is
also known as a myocardial infarction,
because part of the heart muscle
(myocardium) may literally die (infarct). A
heart attack occurs when one of the
coronary arteries becomes severely or
totally blocked, usually by a blood clot.
Heart Attack
Heart Attack
Ruptured septum
Coronary Artery Disease
Coronary artery disease (CAD) is a chronic
disease in which the coronary arteries
gradually harden and narrow
(atherosclerosis).
This is a normal coronary artery. The lumen is
large, without any narrowing by plaque deposits.
The muscular arterial wall is of normal proportion.
The coronary artery shown here has narrowing of
the lumen due to build up of atherosclerotic
plaque. Severe narrowing can lead to angina,
ischemia, and infarction.
This distal portion of coronary artery shows significant
narrowing. Such involvement is typical of severe coronary
atherosclerosis, such as can appear with diabetes mellitus
or a history of high cholesterol. This would make a
coronary bypass operation difficult.
Atherosclerosis
• Also known as “hardening
of the arteries,”
atherosclerosis is a
disease in which the
arteries are hardened and
narrowed as a result of
plaque that has built up
along the inside of the
artery walls.
Aortic Aneurysm
Here is an example of an
atherosclerotic aneurysm of the aorta
in which a large "bulge" appears just
above the aortic bifurcation. Such
aneurysms are prone to rupture when
they reach about 6 to 7 cm in size.
They may be felt on physical
examination as a pulsatile mass in
the abdomen. Most such aneurysms
are conveniently located below the
renal arteries so that surgical
resection can be performed with
placement of a graft.
Aortic Aneurysm
This speed CT scan
with contrast
demonstrates an
abdominal abdominal
high aortic aneurysm
approximately 6 cm in
diameter. At this size,
there is increased risk
for rupture.
Anemia
• Anemia occurs when the
number of red blood cells
(or the Hb in them) falls
below normal and the
body gets less oxygen and
therefore has less energy
than it needs to function
properly
• When the number of red blood cells
decreases, the heart works harder,
pumping more blood to send more oxygen
throughout the body. If the heart works too
hard, it can develop a rapid heartbeat
(tachycardia), and/or another serious
condition known as left ventricular
hypertrophy (LVH), an enlargement of the
heart muscle that in turn can lead to heart
failure.
Types of Anemia
• Hemorrhagic anemia: results from sudden
hemorrhage
• Hemolytic anemia: results from bacterial
infections
• Pernicious anemia: results from a lack of Vitamin
B12
• Aplastic anemia: results from destruction of bone
marrow by cancer
• Iron deficiency anemia: results from a diet low in
iron or slow or prolonged bleeding
• Abnormal hemoglobin in RBCs: sickle cell
anemia
Sickle Cell Anemia
• Sickle cell anemia is a serious condition in which
the red blood cells can become sickle-shaped
(that is, shaped like a “C”).
• Sickle-shaped cells don’t move easily through
blood. They’re stiff and sticky and tend to form
clumps and get stuck in blood vessels.
• The clumps of sickle cells block blood flow in the
blood vessels that lead to the limbs and organs.
Blocked blood vessels can cause pain, serious
infections, and organ damage.
Sickle Cell Anemia
Leukemia
• Leukemia or leukaemia (Greek leukos
λευκός, “white”; aima αίμα, “blood”)
• a cancer of the blood or bone marrow and
is characterized by an abnormal
production of blood cells, usually white
blood cells (leukocytes). It is part of the
broad group of diseases called
hematological neoplasms.
Leukemia
• White blood cells, which are involved in
fighting pathogens, may be suppressed or
dysfunctional. This could cause the
patient's immune system (white blood cells
etc.) to start attacking other body cells.
Leukemia
Some other related symptoms:
• Fever, chills, night sweats and other flu-like symptoms
• Weakness and fatigue
• frequent mood swings
• Loss of appetite and/or weight
• Swollen or bleeding gums
• Excess bleeding (from a minor cut)
• Neurological symptoms (headache)
• Enlarged liver and spleen
• Easy bruising
• Frequent infection
• Bone pain
• Joint pain
• Dizziness
• Swollen tonsils
Normal blood smear
Leukemia blood smear
Bleeding disorders
• Thrombocytopenia
– Platelet deficiency
– Even normal movements can cause bleeding
from small blood vessels that require platelets
for clotting
• Hemophilia
– Hereditary bleeding disorder
– Normal clotting factors are missing
Hemophilia
• Hemophilia is a rare genetic bleeding disorder
caused by a shortage of certain clotting factors.
Blood clotting factors are needed to help stop
bleeding after a cut or injury to prevent
spontaneous bleeding
• In a healthy individual, a minor bump can
damage a blood vessel, causing blood to leak
into the surrounding tissue, producing a bruise.
A process called hemostasis (coagulation) plugs
the hole in the damaged vessel and forms a clot
that stops the blood loss and limits the size of
the bruise.
Hemophilia
• In people with hemophilia and related problems,
bleeding can take a very different course. The
blood does not clot normally because of one or
another of the blood proteins (clotting factors)
that collaborate to repair damaged vessels and
form clots is defective, deficient, or totally
absent.
Hemophilia
• The photo to the right shows
a person with mild
hemophilia after an injection
in the buttocks and the
bruising that occurred
afterward from uncontrolled
bleeding. When the blood
doesn't clot normally, even
minor injuries can cause
serious bleeding. This can
lead to blood loss, injury to
internal organs, or
permanent damage to
muscles or joints.
Hemophilia
• The idea that people with hemophilia can bleed
to death from a minor cut or injury is a
misconception. In fact, external bleeding is
seldom a serious problem for hemophiliacs.
They may bleed somewhat longer than other
people, but minor bleeding episodes can
generally be controlled by ordinary first aid
measures.
• Though there is no cure for hemophilia, it can be
controlled with regular infusions of the deficient
clotting factor