Transcript The Heart and blood vessels and circulation Chapter 12 and 13

The Heart and blood vessels and
circulation Chapter 12 and 13
1
I. The heart and the circulatory
system
A. Blood flows through a network of
blood vessels that extend between the
heart and the peripheral tissues.
2
1. Blood vessels are subdivided into a
pulmonary circuit, which carries blood
to and from exchange surfaces of the
lungs and a systemic circuit, which
transports blood to and from the rest of
the body.
3
4
2. Arteries, or efferent vessels carry blood
AWAY from the heart.
3. Veins or afferent vessels carry blood TO
the heart.
4. Capillaries are small, thin walled vessels
between the smallest arteries and veins.
5
5. The thin walls of the capillaries permit the
exchange of nutrients, dissolved gases, and
waste products between the blood and
surrounding tissues.
6. The heart is a small organ, the size of a
clenched fist.
7. The heart consists of four chambers.
6
8. The right atrium receives blood from the
systemic circuit and the right ventricle
discharges blood into the pulmonary lungs.
9. The left atrium collects blood from the
pulmonary circuit, and the left ventricle ejects
it into the systemic circuit.
7
8
10. When the heart
beats, the atria
contract first then
the ventricles. The
two ventricles
contract at the same
time and eject
volumes of blood.
9
B. The Anatomy and Organization of the
Heart
1. The heart lies directly behind the
sternum.
2. The heart is surrounded by the pericardial
cavity.
3. The lining of the pericardial cavity is a
serious membrane called the pericardium.
10
4. The heart is a hollow, muscular
organ that contracts at regular intervals,
forcing blood through the circulatory
system.
11
5. The walls of the heart are made up of three
layers of tissue.
a. The outer and inner layers are epithelial
tissues, which cover and protect other
tissues.
b. The middle layer is cardiac muscle tissue.
12
6. Cardiac muscle tissue has a rich
supply of blood.
7. The cells make up cardiac muscle
tissue are loaded with mitochondria.
(why?)
13
8. The right side of the heart pumps blood
from the body into the lungs where oxygenpoor (deoxygenated) blood gives up carbon
dioxide and picks up the oxygen.
9. The left side of the heart pumps oxygenrich (oxygenated) blood from the lungs to the
rest of the body.
14
10. The heart is enclosed in protective
sac of tissue called the pericardium.
11. Dividing the right side from the left
side is a septum or wall. The septum
prevents the mixing of oxygen-poor and
oxygen –rich blood.
15
12. On each side of the septum are
two chambers. The upper chambers,
which are called atria, receive blood
coming into the heart.
13. The lower chambers, which are
called ventricles, pump blood out of the
heart.
16
C. Internal anatomy and organization
1. Each atrium communicates with the
ventricle on the same side through an
atrioventricular (AV) valve.
2. The valve ensures a one-way flow of
blood from the atria into the ventricles.
17
3. The right atrium receives blood from two
large veins, superior vena cave and the
inferior vena cava.
4. The superior vena cava delivers blood
from the head, neck upper limbs, and chest.
5. The inferior vena cava carries blood from
the rest of the trunk, the viscera and the
lower limps.
18
19
6. The cardiac veins of the heart return
venous blood to the coronary sinus, which
opens into the right atrium.
7. Blood travels from the right atrium into
the right ventricle through an opening
bounded by three flaps.
8. These flaps or cusps are part of the AV
value, they are also known as the tricuspid
valve.
20
9. Blood leaving the right ventricle flows into
the pulmonary trunk.
10. Blood flows into the left and right
pulmonary arteries. These vessels branch
out.
11. The left atrium has a valve the left
atrioventricular valve or bicuspid valve. Also
called the mitral valve.
21
D. Differences between right and left
ventricles.
1. The function of an atrium is to collect
blood returning to the heart and deliver
that blood to the attached ventricle.
22
II. The heart beat
A. The alternating contraction and relaxation
of the heart chambers is called the cardiac
cycle.
1. The heart does not contract in a single
motion.
2. Once the ventricles contract, the blood
must be directed out through the arteries and
not back up into the atria.
23
3. Once blood has entered the arteries,
it must be prevented from flowing back
as the heart relaxes.
4. Pressure in one direction opens the
valves, while reverse pressure forces
the valves tightly closed.
24
5. Two seminar valves allow blood to enter
the pulmonary artery and the aorta when the
ventricles contract but prevent it from
returning as the ventricles relax.
6. The contraction of the heart is initiated
and coordinated by a pacemaker. A cluster of
specialized muscle cells that produce
spontaneous electrical signals at a regular
rate.
25
7. The heart’s primary pacemaker is the
sinoatrial (SA) node, located in the wall of the
right atrium.
8. When a pacemaker fails to coordinate
muscle contractions, a condition known as
fibrillation occurs.
9. Fibrillation of the ventricles is soon fatal
because blood is not pumped out of the heart
to the brain and other organs but is merely 26
B. Blood vessels
1. Three types of blood vessels that are
involved in the circulatory system are arteries,
capillaries and veins.
2. Arteries carry blood away from the
heart, In general, the walls of arteries are
thicker than veins.
27
3. This helps arteries withstand the high
pressure of blood.
4. Except for pulmonary arteries, all arteries
carry oxygen rich blood.
5. The artery that carries oxygen-rich blood
from the left ventricle to all parts of the body
is the aorta.
28
6. The aorta is the largest artery in the
body. As the aorta leaves the heart it
continues to branch into smaller arteries
and finally to arterioles.
7. Arterioles branch into networks of
very small blood vessels called
capillaries.
29
8. The flow of blood moves from
capillaries into veins. Veins form a
system that collects blood from every
part of the body and carries it back to
the heart. The smallest veins are called
venues.
30
C. Pathways of circulation
1. There are two pumps involved in the
circulatory system. One of the two pumps is
called the pulmonary circulation.
2. This consists of the heart and lungs.
The circulation begins at the right ventricle
and ends at the left ventricle.
31
3. Oxygen depleted blood is pumped out of
the right ventricle into the lungs through the
pulmonary arteries. These are the only
arteries that carry deoxygenated blood.
4. Blood returns to the heart through the
pulmonary veins. The only veins that carry
oxygen rich blood.
32
5. The other pump, consisting of the left
atrium and ventricle, powers systemic
circulation. Starts at the left ventricle and
ends at the right atrium.
6. Newly oxygenated blood from the lungs
enters the left atrium through pulmonary
veins and is passed to the left ventricle.
33
34
III. Blood pressure
A. A measure of the force that blood
exerts against a vessel wall is called
blood pressure.
1. The body regulates blood pressure
in two ways.
35
3. When blood pressure is too low, the
autonomic nervous system constricts the
walls of the arteries. This reduces their
diameter and helps to raise blood pressure.
4. When blood pressure is high, the kidneys
remove more water from the blood, lowering
the total amount of fluid in the circulatory
system. The loss of fluid from the blood
lowers the blood pressure.
36
4. Problems can arise when blood pressure is
either too low or too high.
5. Low blood pressure slows down the rate
at which blood flows through the body. The
part of the body that area far away from the
heart, hands and feet do not receive enough
blood. This is called hypotension.
37
6. High blood pressure or hypertension
occurs when blood pressure is high, the heart
works much harder to pump blood, causing
the heart muscle to weaken.
7. People with high blood pressure are also
more likely to develop problems in the
arteries outside the heart.
38
8. It is not known what causes high blood
pressure but it is known certain things raise
ones chance of high blood pressure. Things
such as obesity, and family back ground.
9. Medicine can help to regulate blood
pressure along with exercise, diet and not
smoking.
39
10. Blood pressure can be measured by a
sphygmomanometer.
11. Blood pressure is recorded as two
numbers separated by a slash.
12. The number on the top is the systolic
pressure. This is when the heart is working.
40
13. The bottom number is the diastolic
pressure. This is when the heart is NOT
working, or when it is done.
14. An average blood pressure for a 20
year old is 120/70.
41
The End
42