Transcript The Cardiovascular System

The Cardiovascular System
•Your Heart
and Stuff
The Cardiovascular System
includes the heart, blood
vessels, and blood.
Cardiology- the study of the
heart and the diseases
associated with it.
Functions
1.
2.
3.
to supply cells & tissues with
oxygen
to circulate substances &
nutrients
to remove wastes (CO2 & urea)
from cells and tissues.
Heart Coverings
Pericardium – covers the heart, has 3
layers
 Fibrous pericardium - outermost
 Parietal pericardium - middle
 (Pericardial cavity)
 Visceral pericardium (continuous with
epicardium) - innermost
The Heart Wall (3 layers):
epicardium (visceral pericardium)
– reduces friction
2. myocardium - cardiac muscle
tissue (bulk of heart)
3. endocardium – smooth inner
lining of heart chambers and
valves.
1.
Heart Chambers
The upper chambers – atria (atrium) blood flows here
1st. Pumps to ventricles
 The lower chambers – ventricles, pump blood out to
body or lungs.
 The right side of your heart receives blood (deoxy) from
the body and pumps it to the lungs.
 The left side of the heart receives blood (oxy) from the
lungs and pumps it out to the body
 A solid wall-like septum separates the atrium and
ventricle on the right from those on the left – so blood
on one side never mixes with blood on the other side

Why is this the right side?
And this the left?
Heart Valves
 Tricuspid Valve –btwn RA and RV
 Pulmonary Valve –allows blood to leave
RV
– Pulmonary means lungs.
 Bicuspid (mitral) Valve – btwn LA and LV
 Aortic Valve – allows blood to leave LV
What color is blood?
Blood when oxygenated is red
 However, deoxygenated is not blue as
believed. It is actually a redish purple.
 It appears blue because the color is
diffused looking through the skin
 This is also why veins typically appears
almost green in African-Americans.

Blood Flow
 Blood
low on O2 (deoxygenated) enters
Right Atrium through the superior and
inferior venae cavae and coronary sinus
 Right Atrium wall contracts, and blood
passes thru tricuspid valve into Right
Ventricle (only adds 30% of vol. to RV)
 Right Ventricle contracts, and blood is
forced thru pulmonary valve into
pulmonary trunk divides into
pulmonary arteries(left & right)to lungs
Blood Flow cont.
 pulmonary
arteries take blood to
lungs; gas exchange occurs between
blood and air in alveoli
 Carbon Dioxide is released. Oxygen is
taken in. Blood goes from
deoxygenated to oxygenated
 Freshly oxygenated blood returns to
heart thru the pulmonary veins that
lead to Left Atrium
Blood Flow cont.
Left Atrium wall contracts, and blood moves
thru bicuspid valve into Left Ventricle
 Left Ventricle contracts, blood moves thru
aortic valve and into the aortaaorta carries
oxygenated blood to tissues
 Oxygen to tissues, Carbon Dioxide made in
tissues released into blood
 Deoxygenated blood is sent back to heart
thru superior and inferior vena cava

Heart Sounds
Heart sounds are produced by vibrations in the
tissue associated with the closing of the valves.
 The first part of the heart sound (lubb) is heard
during ventricular contraction when the valves
between the Atrium & Ventricles closes.
 The closing causes the blood to stop flowing or
back up causing a sound almost like waves
crashing on a beach. They do not make a
sound until they crash. Blood does not make a
sound when flowing; only when it is stopped
and crashes into heart valve.

Heart Sounds cont’d
The second part of the heart sound (dubb)
happens during ventricular relaxation when
the pulmonary and aortic valves snap shut
 Heart sounds give doctors an indication of
how well the valves are functioning (ex:
murmurs)
 Mitral Valve prolapse is usually identified by
lubb-dubb-squish. The squish is the valve
closing improperly and some blood still is
leaking through.

National geographic website

Here the heart Hit next twice
Cardiac Muscle fibers
 Cardiac
fibers are highly
branched, so when any part of
the network is stimulated, the
whole unit contracts (called a
functional syncytium)
 There are 2 syncytia – the atrial
syncytium and the ventricular
syncytium
Conduction of a cardiac impulse:
 Starts
at the sinoatrial (S-A)
node located in the RA
 The S-A node is self-exciting (no
outside stimulation needed) and
is rhythmic (initiates 70-80
impulses/min. in an adult)
 Called the “pacemaker”
Conduction of a cardiac impulse:
 impulse
generated by the S-A node
causes the atrial syncytium to
contract
 impulse then travels to the
atrioventricular (A-V) node located
in the septum that separates the
atria
Conduction of a cardiac impulse:
 impulse
is delayed as it passes
thru the A-V node, allowing time
for the atria to empty and the
ventricles to fill with blood
 impulse
then travels thru a bundle
of fibers called the bundle of His
located in the interventricular
septum.
Conduction of a cardiac impulse:
The bundle of His gives rise to Purkinje fibers
 The Purkinje fibers extend down into the apex of
the heart and curve upward thru the walls of the
ventricles
 As impulse passes thru Purkinje fibers it
stimulates the ventricular syncytium to contract
 Ventricles squeeze up from the bottom of V to
squeeze blood out of heart.

Blood vessels
 Arteries
– carry blood away from heart; strong, thick;
carry blood under high pressure;
composed of mainly smooth muscle tissue
– Not always oxygenated blood. Pulmonary
artery takes deoxygenated blood to lungs
away from heart.
– Are typically deeper than veins
 Arteries subdivide into smaller tubes called
arterioles.
Blood vessels cont’d
 Capillaries
– are the smallest blood vessels. They connect the
arterioles with the venules.
– Capillary walls are thin enough to allow
substances to pass through such as O2 & CO2
– Capillaries are microscopic and are only big
enough for one red blood cell to go through at a
time. If you can see it; it is not a capillary.
– 10-40 billion capillaries in your body
– No cell is 1/100 of cm from a capillary
Blood vessels cont’d
 Veins
– Venules are small vessels that merge to
form veins; parallel to arterioles
– these vessels carry blood back to heart
and are not always deoxygenated.
– Venules and veins have thinner walls
than arteries because the blood pressure
is less.
The Cardiac Cycle

The series of events that constitute a
heartbeat
– The atrial walls contract; the ventricle
walls are relaxed
– The ventricle walls contract; the atrial
walls relax
– Both the atria and the ventricles relax
– Ventricle contractions control blood
pressure
– Contracting – systole
– Relaxation - diastole
Blood Pressure
 The force blood exerts against the inner walls
of blood vessels
 Usually refers to the pressure in the arteries
supplied by the aorta
 When the ventricles contract blood moves
into the aorta and pulmonary trunk,
increasing pressure
 maximum pressure during ventricular
contraction is called the systolic pressure
Blood Pressure
 When ventricles relax, arterial pressure drops
 The lowest pressure before the next ventricular
contraction is called the diastolic pressure
 If there’s a drop in blood pressure, walls of
veins constrict, helping to maintain blood
pressure by returning more blood to heart.
(Less blood in veins if veins are smaller)
 This ensures a nearly normal blood flow even
when as much as 25% of blood volume is lost.
Taking Blood Pressure
Normal Blood Pressure 120/80.
 Increase blood pressure until can not hear any
flow because artery closed. Cuff pressure is
greater than systole & diastole so blood vessels
closed all the time. (Contraction & Relaxation)

Taking Blood Pressure
Let blood pressure come down until under
120. During Systole (contraction),
pressure in arteries is greater than cuff, so
artery open only during systole
 But during diastole (relaxation) pressure of
cuff is greater than pressure in blood
vessels so blood vessels are closed.

Taking Blood Pressure
The walls of the blood vessels go in and
out causing turbulent flow of blood.
 Can hear turbulent flow because walls of
arteries going in and out do to change in
pressure.
 Under 80 silent because cuff pressure less
diastole pressure so arteries stay open.
 Blood pressure always recorded as
systolic = 120
diastolic 80

Pulse Rate
 The pulse rate is equal to the rate at
which the ventricles contract or equal
to heart rate.
 The pulse is the alternate expanding
and recoiling of the artery walls.
Pulse
Blood vessel disorders
 Arteriosclerosis-
degenerative
disease in which the arteries lose
elasticity; the vessels become
brittle and can rupture easily;
associated with fatty diet, genetics,
lack of exercise, cigarette smoking,
etc.

Go to Heart Attack Then Blocking the
Artery to watch video
Arteriosclerosis
Blood vessel disorders
 Aneurysm-
a bulge in a blood
vessel; this area of the blood
vessel then weakens and may
burst; can result from trauma, high
blood pressure, infections, or
genetic defects
Aneurysm
Blood vessel disorders cont’d

Varicose veinsirregular dilations
in superficial
veins, especially
of the legs;
associated with
prolonged
increased back
pressure, also
with crossing
legs.
Blood vessel disorders cont’d

Hypertension – high
b.p.; caused by
kidney disease, high
Na+ intake, obesity,
stress,
arteriosclerosis; left
ventricle works
overtime so
myocardium
thickens, enlarging
heartcoronary
vessels can’t feed
overgrowth so parts
of heart die
Disorders, cont.

Anemia – condition in which the
oxygen carrying capacity of the blood
is reduced; symptoms: fatigue,
intolerance to cold, and paleness.
– Nutritional Anemia – inadequate diet,
especially lacking in iron and vitamin
B12
– Sickle-Cell Anemia – abnormal kind of
hemoglobin results in cells shaped like a
sickle (bent); they can rupture easily and
often get stuck together; (genetic)
Types of Anemia
Pericarditis
Inflammation of the pericardium and
therefore an enlargement of the
pericardial sac.
 This causes an increase in pressure on the
outside of the heart and causes the heart
to have to work harder
 Can cause heart attack
 Treatment – typically the fluid is drained
with a needle into the pericardial sac.

Pericarditis
Blood


1.
Connective tissue with liquid matrix.
Carries oxygen, protects against infection,
promotes clotting, and carries other vital
substances
Plasma


2.
clear, straw-colored (yellowish)
mixture of water (95%), amino acids, proteins, carbs,
lipids, vitamins, hormones, electrolytes, and cellular
wastes
Red Blood Cells (Erythrocytes)



contain hemoglobin (a protein that carries oxygen)
made of Iron – loves oxygen – what causes blood to
change colors. Red to purplish
Also the chemical when changed which causes urine to
be yellow and feces to be brown.
formation of RBC (hematopoiesis) – in red marrow
Blood continued
3. White Blood Cells (Leukocytes)



Can squeeze through vessel walls and move through
interstitial spaces via amoeboid movement
Many kinds of white blood cells; all have different jobs.
Protect against disease in 2 ways:
– Phagocytize bacteria (eat up bacteria like pacaman)
– Produce antibodies (proteins that destroy or disable
foreign particles)
4. Platelets (Thrombocytes)


Cell fragments that help close breaks in vessels and
initiate formation of blood clots - (coagulation)
Causes scabs and stops bleeding.
5 Types of
White Blood
Cells
Red Blood
Cells are
erythrocytes
ABO Blood Types
 Antigen-
protein or carb on RBC
surface
–Presence or absence of antigens is
an inherited trait
 2 major antigens: Antigen A and
Antigen B
 4 possible antigen combinations: A
only, B only, A and B, or neither A nor
B
ABO Blood Types
Antibodies- proteins in the plasma that
destroy foreign substances
 Antibodies develop about 2-8 months after
birth

– If antigen A is absent – a person develops
anti-A antibody
– If antigen B is absent – a person develops
anti-B antibody
ABO Blood Types, cont
Blood Type
Antigen
Antibody
A
A
Anti-B
B
B
Anti-A
AB
A and B
O
Neither A nor B
Neither Anti-A
nor Anti-B
Both Anti-A and
Anti-B
ABO Blood Types, cont.
An antigen and an antibody of the same
type react to clump RBC – so such combos
must be avoided
 Type AB – universal recipients (lacks
antibodies anti-A and anti-B)
 Type O – universal donors (lacks antigens
A and B)
 However, the preferred donor is one with
the matching blood type

 Blood
Rh Blood Type
type – a person is either positive or
negative.
 It takes only 1 gene to be positive.
 erythroblastosis fetalis – When a
mother is RH – and her baby is RH +.
During their first pregnancy some blood is
transferred from baby to mother. The
mother then develops antibodies against
RH+ blood.
erythroblastosis fetalis
Next pregnancy some of the blood from
the mom gets in the baby and the
antibodies cause the blood to agglutinate.
Can cause fatality because of lack of
oxygen (severe anemia)
 Treated by massive transfusions of Rh+
blood for the baby and removal of blood
containing Rh+ antibodies.
