Transcript I. Heart

Cardiovascular System -made up of the heart and blood vessels
I. Heart -four-chambered, like all mammals, birds, and some
dinosaurs; reptiles have an incompletely four-chambered
heart, amphibians have a three-chambered heart, and fish
have a two-chambered heart
-inferential evidence suggests that some dinosaur species,
like Tyrannosaurus rex, were homeothermic
Pulmonary circuit - eliminates
Carbon dioxide via the lungs and
oxygenates the blood
Systemic circuit - delivers oxygen to all
body cells and carries away wastes
4.
Oxygenated
blood pumped
to all body
tissues via
aorta
1. Deoxygenated blood returns
to the heart via superior and inferior
vena cavas
2.
Deoxygenated
blood pumped
to lungs via
pulmonary
arteries
3. Oxygenated blood returns
to heart via pulmonary veins
I. Heart
Left Common carotid artery
Brachiocephalic artery
Left subclavian artery
to lungs
Superior vena cava
Pulmonary artery
Pulmonary veins
Pulmonary veins
Right atrium
Pulmonary (semilunar) valve
Chordae tendineae
Papillary muscle
Interventricular septum
Tricuspid valve
Inferior vena cava
Aorta
Right ventricle
to lungs
Superior vena cava
Pulmonary artery
from lungs
from lungs
Right atrium
Left atrium
Tricuspid valve
Mitral (bicuspid) valve
Inferior vena cava
Right ventricle
Left ventricle
Aortic (semilunar) valve
I. Heart
A. Blood Supply -blood supplied to the heart muscle from the
right and left coronary arteries, which open
directly from the aorta near the aortic valve;
deoxygenated blood returns to the right atrium
via the coronary veins
Rx – Myocardial Infarction -heart attack, leading killer of men and women
in the U.S., 500,000 annually
-death of heart muscle due to blockage of a
coronary artery by an embolus, usually a
blood clot
-death of heart muscle throws heart into
arrhythmia, which is the cause of death from
heart attack
-treated with angioplasty, coronary by-pass
surgery, installation of a pacemaker, bloodthinning drugs and anticoagulants
I. Heart
B. Heart Sounds -created by the simultaneous clapping together
of valves
-first, lower-pitched softer sound “lubb” created
by simultaneous closing of the tricuspid and
mitral valves to prevent backflow of blood into
the atria when the ventricles contract
“lubb” -second, higher-pitched louder sound “dupp”
created by simultaneous closing of the two
“dupp”
semilunar (pulmonary and aortic) valves to
prevent backflow of blood into ventricles when
ventricles relax
Rx – Heart Murmur -extra abnormal heart sound, “gurgle” created by the
backflow of blood through a misshapen heart valve
I. Heart
C. Cardiac
Conduction System -network of specialized muscle tissue in
which cells contain few myobrils,
specialized to initiate and distribute
impulses instead of contract
-S-A (sinoatrial) note, or pacemaker
node, lies in wall of right atrium and
S-A node
A-V node
initiates impulses, which, after causing
atria to contract, are conducted to the
A-V (atrioventricular node)
-A-V node conducts impulses to the A-V
bundle and then to the Purkinje fibers,
which stimulate muscle fibers in
A-V bundle
ventricular walls to contract
-papillary muscles anchor cusps of
atrioventricular valves by chordae
Purkinje fibers
tendineae to prevent backflow
II. Blood Vessels
A. Arteries and Arterioles -strong, elastic vessels with smooth
muscle walls which carry blood away
from the heart under pressure
-smooth muscle vasoconstriction
increases blood pressure and smooth
muscle vasodilation decreases blood
pressure
1. Blood Pressure -pressure exerted on the walls of the of
the systemic arteries
-pulse due to expanding of elastic arteries
120 mm Hg
during the contraction of the ventricles,
80 mm Hg
can be felt at superficial pulse points
a. Systolic pressure -blood pressure when ventricles are
Not normal,
but average,
contracted
blood pressure
b. Diastolic pressure -blood pressure when ventricles
are relaxed
II. Blood Vessels
A. Arteries and Arterioles
Rx – Atherosclerosis -deposits of cholesterol and saturated fats form
plaques within the arteries, restricting blood flow
and initiating formation of blood clots
-increases risk of heart attack, high blood pressure
and heart disease, and aneurysm, a weakening of the
arterial wall which may rupture
B. Capillaries -smallest blood vessels; walls only one squamous
epithelial cell thick, lie between arterioles and
venules
-diameter only one red blood cell wide, RBC’s
must proceed in slowly in single file
-thin walls and slow speed allow for exchange of
lipid-soluble gases through the cell membranes
and lipid-insoluble water and ions through slitlike openings in the capillary walls
II. Blood Vessels
C. Veins and Venules -carry deoxygenated blood back to the
heart
-have thinner walls, larger lumens, contain
most of the blood in the body
-blood is not under pressure, only moves
along because of the blood arriving
behind it which pushes it along
-contain valves which prevent backflow,
only allow blood to flow toward heart
Rx – Varicose Veins -veins, especially in legs, become stretched and
flattened from prolonged increased back pressure
due to standing or sitting with legs crossed
-valves no longer fit the stretched out veins, cannot
prevent backflow of blood, and blood pools in legs
and feet especially, creating pain and swelling
-treated by destruction or surgical removal of veins
Rx – Hypertension -high blood pressure
-caused by arteriosclerosis, or hardening of the
arteries, in which arterial walls lose elasticity and
vessel lumens narrow
-caused by kidney diseases that result in reduced
blood flow to kidney cells, which release enzyme
renin that leads to the production of the
vasoconstrictor angiotension II, which constricts
peripheral arteries
-caused by high sodium intake, stress, and obesity
-leads to left ventricle having to work too hard,
myocardium becomes enlarged, coronary blood
vessels can’t support overgrowth, heart muscle dies
and is replaced with scar tissue until the enlarged and
weakened heart dies
-treated with exercise, weight control, diet low in
sodium, reducing stress, and drugs like diuretics,
which increase urinary excretion of water and Na+