Transcript Cardiac Cycle

CHAPTER 22
INTERNAL TRANSPORT
Pgs 678-710
22A
THE CIRCULATORY SYSTEM
Pgs 678-698
22A-1
THE BLOOD
Pgs 679-686
THE BLOOD

Blood transports:
oxygen, nutrients, and hormones to all body cells
 carbon dioxide to the lungs
 waste molecules to the kidneys.


5 L of blood for healthy adults.
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Some cells are red, while others are clear
THE BLOOD
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When centrifuged, blood
separates into two distinct layers
that are separated by a thin
third layer.

The upper layer is plasma.

The bottom layer is RBCs

The thin center layer is called
the buffy coat and is composed
of platelets and WBCs
THE BLOOD
90% water
 10% protein, dissolved gases, minerals, nutrients,
hormones, and waste products.
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
The composition varies depending on diet and
health status.
THE BLOOD
FORMED BLOOD COMPONENTS
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Cellular components are 45% of the total blood
volume including RBCs, WBCs, and platelets.
All originate from a single type of stem cell, the
hemocytoblast.
Hemocytoblasts are located in the bone marrow
and respond to certain growth factors.
FORMED BLOOD COMPONENTS
ERYTHROCYTES (RBCS)
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Early in their life cycle they contain a nucleus
with very little hemoglobin.
As they mature, the nucleus is extruded and the
amount of hemoglobin increases. At this point the
structure is no longer a true cell.

No mitosis and few cellular structures.

Biconcave shape
ERYTHROCYTES (RBCS)
ERYTHROCYTES (RBCS)
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Unable to move by themselves, but are carried by
the current of blood flow.
Oxyhemoglobin is brighter than normal
hemoglobin.
Average life span of an erythrocyte is 90-120
days. Specialized cells in the liver and spleen
break down old erythrocytes.
LEUKOCYTES (WBCS)

No hemoglobin

Twice the size of Erythrocytes.

No definite shape

They have nuclei throughout entire life span.
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Can move independently
LEUKOCYTES (WBCS)

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Various types of leukocytes.
In a healthy person the ratio of leukocytes to
erythrocytes is about 1:600
If the first leukocytes to arrive at a site of
infection are not successful in stopping the
infection, the invading organisms are free to
multiply and injury the body’s cells
LEUKOCYTES (WBCS)

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Chemicals released from the injured cells initiate
an inflammatory response.
This results in additional leukocytes moving out
of the blood vessels to engulf and digest or to kill
the harmful invaders. Leukocytes also digest and
remove injured and dead body cells.
LEUKOCYTES (WBCS)

The accumulation of dead leukocytes, dead
organisms, and broken cells forms a thick fluid
called pus.
LEUKOCYTES (WBCS)
PLATELETS & BLOOD CLOTTING
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Platelets (thrombocytes) develop from large cells
called megakaryocytes, which are derived from
the hemocytoblasts in the red bone marrow.
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No nucleus
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Half the size or a red blood cell.
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Injured tissue releases a chemical that causes the
platelets to stick to the broken edges of blood
vessels.
PLATELETS & BLOOD CLOTTING
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The platelets then release serotonin which
causes the smooth muscles of the vessel walls to
contract.
Platelets also play an important role in
coagulation, the formation of a blood clot.
Coagulation occurs as a result of complex
biochemical pathways that involve multiple
inter-dependent reactions, enzymes, and
coenzymes.
PLATELETS & BLOOD CLOTTING
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As platelets stick to the rough edges of damaged
tissue, they release a substance that aids in the
formation of thromboplastin
The formation of thromboplastin triggers the
reaction converting the protein prothrombin
into thrombin.
Thrombin is used to change fibrinogen into
insoluble threads of fibrin.
PLATELETS & BLOOD CLOTTING
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The fibrin threads form a microscopic meshwork
that entangles the blood cells to form a blood clot.
Chemicals in the blood gradually dissolve clots as
the vessel wall heals.
An abnormal clot that forms within a blood vessel
is called a thrombus.
PLATELETS & BLOOD CLOTTING
PLATELETS & BLOOD CLOTTING
PLATELETS & BLOOD CLOTTING
PLATELETS & BLOOD CLOTTING
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A thrombus readily forms where the blood flows
slowly or where the lining of the blood vessel in
narrow and rough, as in the disease
atherosclerosis.
If the thrombus or a portion of it becomes
dislodged and floats in the blood vessels, it is
known as an embolus.
BLOOD TYPES
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Determined by the presence or absence of protein
or carbohydrate molecules in the membranes of
the erythrocytes.
These molecules are called “antigens”.
Antigens stimulate the formation of antibodies
that cause blood to clump.
ABO BLOOD GROUP

The presence or absence of two antigens, A and
B, in the membranes of the erythrocytes
determines the ABO blood type.
Antigen A = Blood type A
 Antigen B = Blood type B
 Antigen A & B = Blood type AB
 No A or B Antigen = Blood type O
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ABO BLOOD GROUP
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In addition to antigens, three of these blood types
also have antibodies.
Type A: produces anti-B antibodies
 Type B: produces anti-A antibodies
 Type AB: produces neither antibody
 Type O: produces both anti-A and anti-B
antibodies
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ABO BLOOD GROUP
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If type A blood is accidentally given to a person
who has type B blood, the person’s body will
immediately recognize that the A antigen is a
foreign substance, and the anti-A antibodies will
quickly attack the A antigens.
This causes the donor’s erythrocytes to
agglutinate. Leading ultimately to death.
THE RH SYSTEM
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Named after the rhesus monkey from which the
antigen was first isolated.
Involves the presence or absence of an antigen in
the erythrocyte membrane.
85% of Americans are Rh(+)
THE RH SYSTEM
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Normally, human blood plasma does not contain
anti-Rh antibodies, but these antibodies can be
stimulated into production in an Rh- person.
During pregnancy, if the fetus is Rh+ and the
mother is Rh-, the mothers body forms anti Rh
antibodies.
THE RH SYSTEM
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The antibodies remain in her blood plasma but
pose no danger until she becomes pregnant with
another Rh+ baby.
This can lead to death of the fetus.
BLOOD TYPES
22A-2
THE HEART
Pgs 686-691
THE HEART
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4 chambered pump

Size of a clenched fist with a weight of 340 g
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Approx. 100,800 beats per day.
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Every heard beat pushes about 80 ml (2.4 oz) of
blood or 8000 L (2100 gal) per day.
8000 L BARREL
STRUCTURE OF THE HEART
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
Covered by the pericardium which is a loose
cover that prevents rubbing against the lungs
and inner chest wall.
The pericardial sac is filled with pericardial
fluid which reduces friction between the heart
and surrounding structures.
STRUCTURE OF THE HEART
STRUCTURE OF THE HEART
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Epicardium:

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Myocardium:
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outermost layer composed of connective tissue. Keeps
the heart muscle from becoming saturated with
pericardial fluid.
thickest portion. Muscle layer that pumps the blood.
Endocardium:

innermost lining of the heart. Prevents blood from
saturating the myocardium.
STRUCTURE OF THE HEART
STRUCTURE OF THE HEART
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Septum:
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Atria:
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A muscular wall that separates the left and right
portions of the heart.
upper chambers. Atrial myocardium is thin because
these chambers primarily receive blood.
Ventricles:
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lower chambers. Thicker because they have the
responsibility of pushing blood into the blood vessels
of the body.
STRUCTURE OF THE HEART

Atrioventicualar valves:
Separates the atria from the ventricles.
 Right AV valve is the tricuspid valve
 Left AV valve is the bicuspid valve.
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Semilunar valves:

located at exits of ventricles.
STRUCTURE OF THE HEART
BLOOD FLOW THROUGH THE HEART
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Superior vena cava:
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Inferior vena cava:
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drains body parts above the heart.
drains body parts below the heart.
Both empty into the right atrium.
BLOOD FLOW THROUGH THE HEART
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As the right atrium fills with blood, it contracts
squeezing the blood through the tricuspid valve
and into the right ventricle.
When right ventricle contracts, the tricuspid is
forced shut, and the pulmonary semilunar
valve opens to allow flow to pulmonary artery.
BLOOD FLOW THROUGH THE HEART
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Each of the two main branches of the pulmonary
artery leads to a lung. As blood flows through the
capillaries surrounding the alveoli, oxygen is
added to the hemoglobin of the blood.
Richly oxygenated blood returns to the left
atrium through the pulmonary veins.
BLOOD FLOW THROUGH THE HEART
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The left atrium then contracts, squeezing the
blood through the bicuspid valve and filling the
left ventricle.
As the left ventricle contracts, the bicuspid valve
shuts with considerable force, and blood rushes
through the aortic semilunar valve into the aorta.
THE CARDIAC CYCLE
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Cardiac Cycle = heartbeat
The contraction of the heart muscle is known as
systole.
The relaxing and filling of the heart with blood is
called diastole.
THE CARDIAC CYCLE
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SA node: starts each systole and thus sets the
pace of the heart. The SA node rate can be
increased or decreased by input from the nervous
system.
The SA node is located in the right atrium near
the entrance of the superior vena cava.
THE CARDIAC CYCLE
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The electrical impulse from the SA node is
transmitted through muscle tissue to both atria,
causing them to contract together.
About 0.1 second later, the impulse reaches the
AV node, where there is a brief pause to allow for
proper emptying of the atria.
THE CARDIAC CYCLE
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When the AV node “fires”, it sends an electrical
impulse down the bundle of His to the wall of
each ventricle.
The fibers of the ventricle walls contract together
and efficiently push the blood into the pulmonary
artery and the aorta.
THE CARDIAC CYCLE
THE CARDIAC CYCLE
THE HEART RATE
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The typical resting heart rate of an adult is 70
bpm.
During moderate exercise is shoots up to 120
bpm.
If the heartbeat is more than 140 bpm,
ventricular diastole may be too short to fill.
22A-3
BLOOD VESSELS AND
CIRCULATION
Pgs 691-695
BLOOD VESSELS
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Heart and blood vessels form a closed system.
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Arteries carry blood away from the heart.
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Veins carry blood toward the heart
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Capillaries connect the two
BLOOD VESSELS
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Arteries are typically found in deeper tissues.
Almost every cell in the body is near a blood
capillary.
Strong walls of arteries have three layers:
Outer elastic layer
 Middle muscular layer
 Inner epithelial layer

BLOOD VESSELS
BLOOD VESSELS
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Arteries form smaller vessels known as
arterioles, which in turn branch into
microscopic capillaries whose walls are only one
cell thick.
The capillaries are the functional units of the
circulatory system. Only through these vessels
can diffusion of materials occur.
BLOOD VESSELS
BLOOD VESSELS
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Next, capillaries merge to form venules which
join with other venules to form veins.
Veins have the same three layers as arteries, just
thinner. Many veins also contain semilunar
valves to prevent reverse blood flow.
BLOOD VESSELS
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All veins, except the cardiac and pulmonary,
drain blood into the superior and inferior venae
cavae. The cardiac veins open directly into the
right atrium, and the pulmonary veins return
oxygenated blood from the lungs to the left
atrium.
PULMONARY CIRCULATION
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The pulmonary circulation carries oxygen
poor blood from the right ventricle to the lungs.
At any moment about 0.5 L of blood is in the
pulmonary circulation.
Requires only a few seconds.
PULMONARY CIRCULATION
SYSTEMIC CIRCULATION
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The systemic circulation consists of the flow of
blood from the left ventricle to all parts of the
body (except the lungs) and then back to the right
atrium.
CORONARY CIRCULATION
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The coronary circulation carries blood into and
out of the heart muscle.
Two coronary arteries that branch off the aorta
just distal to the aortic semilunar valve deliver
nutrients and oxygen to the myocardium.
CORONARY CIRCULATION
CORONARY CIRCULATION
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The flow of blood in the capillaries of the
myocardium nearly stops each time the heart
contracts.
The contracted cardiac muscle fibers compress
the adjacent coronary vessels as they contract.
RENAL CIRCULATION
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The circulation of blood in and out of the kidneys
is known as the renal circulation.
As the blood flows through the kidneys, the waste
materials are removed for excretion as urine. The
blood that leaves the kidneys in the renal veins is
the cleanest blood in the body.
PORTAL CIRCULATION
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The blood from the digestive organs is carried to
the liver by the hepatic portal vein.
The liver also receives oxygenated blood from the
hepatic artery.
These vessels branch as they enter liver and
blood mixes in the liver sinusoids.
PORTAL CIRCULATION
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This flow of blood to the liver is called the portal
circulation.
The liver cells remove toxic substances from the
blood and metabolize foods.
Blood leaves the liver through the hepatic veins
that merge with the inferior vena cava.
PORTAL CIRCULATION
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Blood in the portal vein also contains insulin that
stimulates excess glucose molecules to form
glycogen.
This glycogen can be changed back into glucose
when needed, especially between meals.
22A HOMEWORK