Transcript Unit12cadiovascularsystem

The Cardiovascular
System
Consists of blood, the heart and
blood vessels
Blood
 Blood: A fluid connective tissue
 Blood makes up about 8% of body weight
( 4-6 liters) (pH 7.4)
 Hematology : The study of blood
 Erythropoiesis: RBC formation
 Hematopoiesis: Process of forming any
blood cells
Functions:
 1. Transportation:
 Of gases to/from cells and lungs
 Of nutrients, enzymes, hormones and
blood cells all around the body
 Of wasts from cells to kidneys, lungs and
sweat glands
Functions:
 2. Regulation: ( homeostasis)
 Of pH through buffer systems
 Of Temperature by absorbing and
distribute heat
 Of water content of cells by diffusion
to/from heart
Functions:
 3. Protection:
 Against toxins and invaders with WBCs
 Against blood loss through clotting
Components of blood
 Plasma: (about 50% total volume)
 The liquid portion (97% water)
 Contains various dissolved substances (
gases, nutrients, anti-bodies and fibers)
 Formed Elements: cells and cell
fragments
Erythrocytes: Red Blood Cells
(RBC)
 Lack nucleus and
mitochondria
 Circulating lifespan of 120
days
 Each erythrocyte contains
280 million hemoglobin
molecules
Erythrocytes: Red Blood Cells
(RBC)
 Destroyed by phagocytic cells in
liver, spleen, and bone marrow
 Cannot reproduce in blood stream
 Anemia: abnormal low count in
RBCs
 Erythropoiesis: rbc formation
Erythrocytes: Red Blood Cells
(RBC)
 Woman usually have 4-5 million
erythrocytes per cubic millimeter of
blood
 men have 5-6 million. If this number is
considerably higher
 polycythemia may be the cause. If the
number is considerably less, the
person has anemia.
Erythrocytes
Leukocytes: White blood cells
(wbc)
 Contain nucleus and mitochondria
 Move in ameboid fashion and can
leave closed circulatory system (by
diapedesis: squeeze between
capillaries)
 Function to combat microbes
 Have 5000-10000per mm
NEUTROPHIL
 The nucleus is frequently
multi-lobed with lobes
connected by thin strands
of nuclear material.
 These cells are capable
of phagocytizing foreign
cells, toxins, and viruses.
 When taking a Differential

WBC Count of normal
blood, this type of cell
would be the most
numerous.
NEUTROPHIL
 If the count exceeds this
amount, the cause is
usually due to an acute
infection such as
appendicitis, smallpox or
rheumatic fever.
 If the count is
considerably less, it may
be due to a viral infection
such as influenza,
hepatitis, or rubella.
 Destroy and eat bacteria
and dead cells at
inflamed site
EOSINOPHIL
 The nucleus often has
two lobes connected by a
band of nuclear material.
(Does it looks like a
telephone receiver?)
 The granules contain
digestive enzymes that
are particularly effective
against parasitic worms in
their larval form.
EOSINOPHIL
 These cells also
phagocytize antigen antibody
 These cells account for
less than 5% of the
WBC's complexes.
 Primarily combat large
invaders, such as worms
flukes and decrease
allergic reactions
BASOPHIL
 The basophilic granules in this cell are large,
stain deep blue to purple, and are often so
numerous they mask the nucleus. These
granules contain histamines (cause
vasodilation) and heparin (anticoagulant).
 In a Differential WBC Count we rarely see
these as they represent less than 1% of all
leukocytes
 the count showed an abnormally high
number of these cells, hemolytic anemia or
chicken pox may be the cause
 They intensify inflammation and o allergic
reaction by releasing histamine which
attracts other WBc( they sound the alarm)
BASOPHIL
LYMPHOCYTE
 Its nucleus is very large for the size of the cell
and stains dark purple. (Notice that the nucleus
almost fills the cell leaving a very thin rim of
cytoplasm
 This is the second most numerous leukocyte,
accounting for 25-35% of the cells counted in a
Differential WBC Count.
 the number of these cells exceeds the normal
amount, one would suspect infectious
mononucleosis or a chronic infection
LYMPHOCYTE
MONOCYTE
 This cell is the largest of the leukocytes
and is agranular. The nucleus is most
often "U" or kidney bean shaped; These
cells account for 3-9% of all leukocytes
 In people with malaria, endocarditis,
typhoid fever, and Rocky Mountain spotted
fever, monocytes increase in number.
MONOCYTE
THROMBOCYTES - PLATELETS

Each cubic millimeter of blood should
contain 250,000 to 500,000 of these. If the
number is too high, spontaneous clotting
may occur. If the number is too low,
clotting may not occur when necessary
THROMBOCYTES - PLATELETS
 Platelets, which are
cell fragments, are
seen next to the "t's"
above. (Many of the
other micrographs on
this page contain
them as well.)
Platelets are
important for proper
blood clotting.
Do you know what types of cells
are these?
Do you know what types of cells
are these?
Blood Groups and Typing
• On the surface of all cell membranes (
including RBCs) are highly specific
glycoprotein “flags” which are the basis of
blood typing
• Agglutinogens: membrane based
molecules used for grouping blood into
types ( “friends”)
2 types of grouping blood based on
type of agglutinogens present
• 1. ABO blood grouping : has 2
agglutinogens (A, B)
• The blood plasma also contains proteins
called agglutinins (enemies) that the blood
will react against
Blood Typing
• % pop Blood type
Agglutinogens Agglutinins
accepts
• 42%
A
A
B
A, O
• 10%
B
B
A
B, O
• 4%
•
• 45%
•
AB
A, B
O
NONE
NONE
All
universal acceptor
A, B
Only O
universal donor
Blood Typing
• 2. “Rh” Blood grouping system:
• Based on the presences or absence of a single
flag ( agglutiongen)
• If present = Rh + 85% ++, +• If not
= Rh - 15% -•
• As a general rule Rh negative group can give
safely to Rh positive group, but Rh positive
should not be given to Rh negative
In the ABO system
• The agglutinins are preformed and the first
exposure ( transfusion) of the opposing
blood type will initiate the clumping
reaction
• However in the Rh system, the agglutinins
are not formed until the first exposure to
the “wrong” agglutinogen ( works like
immune system)… therefore clumping
reaction wont occur until 2nd transfusion
Rh factor
• If mom is Rh negative and father is
heterozygous Rh positive there is a 50%
chance the child will be Rh positive
• The Childs Rh positive RBC leak into the
placenta and the moms circulatory system
when the placental tissue breaks down…
causing mom to produce Anti-Rh
antibodies
• The Anti-Rh antibodies pass across the
placenta and destroy the RBC of the Rh
positive child resulting in brain damage,
mental retardation or even death
• This is called Erythroblastic fetalis
• Solution: Rh negative woman receive an
Rh immunoglobulin injection or midway
through 1st pregnancy or no later than 48
hrs after giving birth
Blood Typing
Blood Typing
Blood Typing
BLOOD
DISORDERS
Sickle cell anemia
 An inherited condition
which results in some
erythrocytes being
malformed.
 The gene for this
condition causes the
hemoglobin to be
incorrectly formed, which
in turn causes some
erythrocytes to take on a
crescent shape.
 These cells are not able
to carry adequate
amounts of oxygen to
cells
Polycythemia
 condition in which
there is a net increase
in the total number of
red blood cells in the
body. The
overproduction of red
blood cells may be
due to a primary
process in the bone
marrow or it may be a
reaction to chronically
low oxygen levels or,
rarely, a malignancy.
Thrombocytopenia Purpura
 a blood disorder
characterized by an
abnormal decrease in the
number of platelets in the
blood. Platelets are cells
in the blood that help stop
bleeding. A decrease in
platelets can result in
easy bruising, bleeding
gums, and internal
bleeding.
LEUKEMIA
Hemostasis: prevention of blood
loss
 3 mechanisms:
 1. vascular spasm: damage to smooth
muscle in blood vessels or platelets,
causing a release of chemicals which
cause vasoconstriction… reducing blood
flow/loss lasing about 30 min
 2. Platelet plug formation:
 If thrombocytes (platelets) come in
contact with collagen fibers in a damaged
vessels wall… a chemical change occurs
 The platelets become sticky and cling to
each other and to the damaged area
forming a plug ( thrombus) or clot
 If the clot moves it is called an embolus
I
 3. Coagulaton:
 A clot is a mesh of protein fibers in which formed
elements are trapped
 Over 30 different hormones and enzymes are
involved in coagulation
 Liquid protein fibers in the blood plasma solidify
and form a mesh over the damaged area
 RBCs and platelets become trapped in the
mesh… mean while the fibers shrink, tightening
and closing the wound
 Thrombosis: clotting in an unbroken
vessel… if the clot ( thrombus) moves it is
called an embolus …
 if it drifts until it blocks an small vessel, this
is called an embolism ( can cause heart
attacks, strokes, or death)
 Leukemia: a malignant disease ( cancer)
of blood forming tissue… resulting in
excessive numbers of WBCs which crowd
out the RBCs
 Mononucleosis: viral infection attacking
lymph tissue
 Results in lmphocytes which are abnormal
, no cure, it just runs its course
Heart
 A hollow 4 chambered muscular organ
about the size of a clenched fist and
weights about 255 g in females and 310 g
in males
 Located in the thoracic cavity between the
lungs
 2/3 of the heart is located left of the
midline with the apex in contact with the
diaphragm
Enclosed in a loose fitting serous
sac called pericardial sac
 Functions:
 Separate the heart from other organs
 Contains pericardial fluid for lubricaiton
 Layers of pericardium: outer fibrous ,
inter serous layer
 Pericardial cavity: between parietal
pericardium and visceral pericardium
Layers of heart wall

Epicardium: outermost layer
 Myocardium: cardiac muscle, thickest
portion, it contracts
 Endocardium: thin epithelial lining of the
heart chambers
Chambers and valves
 4 chambers
 The two upper heart chambers are atria (
atrium) (auricles on outside of the heart)
 The wall between the two atria is called the
interatrial septum
 The depression in the interatrial septum is called
the fossa ovalis, which used to be an opening
during fetal development and blood could flow
from right atrium to left atrium (can be seen in
the right atrium)
 The two lower chambers are called the
ventricles
 The wall between the 2 ventricles is called
the interventricular septum
 The left ventrical wall is thicker than the
right, due to the way the blood circulates in
the body
 Chordae tendinae: cords that connect
valves to papillary muscles
 Papillary muscle: small raised projections
of muscle tissue that connect chordae
tendinae to endothelium of heart
 Trabeculae carneae: distinct ridges in
walls of ventricles
 A condition called prolapse involves leaky
valves due to stretched chordae tendineae
Valves
 1. Bicuspid (mitral ) valve: located
between left atrium and left ventricle (
most commonly replaced valve)
 2. Tricuspid valve: located between right
atrium and ventricle
 3. Aortic semilunar valve: opens from
right ventricle to base of aorta
 4. Pulmonary semilunar valve: opens from
left ventricle to pulmonary artery
Coronary circulatory system
 The heart has its own circulatory system
 Most heart problems are due to faulty or blocked
coronary circulation… resulting in poor nutrients
and oxygen supply to myocardium
 Ischemia: reduced blood flow, weakens heart
 Angina: chest ( heart) pain due to ischemia
 Infaction: death of an area of tissue due to an
interupted blood supply
 Myocardial infarction: heart attack due to
infarction and weakened heart , usually
caused by an embolus or a thrombus
 Atherosclerosis: build up of cholesterol
or other fatty compounds on the inside of
blood vessel wall, decreases or blocks
circulation
 Coronary artery disease: a condition of
damaged heart muscle due to one of the
above reductions in blood supply. The
number 1 cause of death in USA
 Heart murmers: unusual sounds
generally due to valve disorders ( leaky):
 1. faulty chordae tendinea
 2. disease damaged valves/ cusps
Cardiac cycle (blood pressure)
 The 2 atria contract, pumping blood into
the 2 ventricles which are relaxed while
being filled.
 Then the ventricles contract while the
relaxed atria are refilled from the vena
cava (pulmonary veins)
 Systole: phase of contraction (top #)
 Diastole: phase of relaxation ( bottom #)
 So during ventricular diastole, the tri and
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bicuspids are open
The 2 atria are in systole and the ventricles are
filling
Then the atrial diastole and ventriclular systole
The cuspids close, similunars open, ventricles
empty, Atria fill
Then brief pause and cycle repeats
8 sec per cycle with about 72 beats per minute
 Heart Rate
Average Heart Rate of some
Mammals
400
300
200
200
50 30
100 28
0
376
9
70 40
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Heartbeats per
minute
can be
determined
using a
Stethoscope
Mammals
Lub
If you listen to
your heartbeat, it
makes a lub dub
sound.
The lub is when blood
is pushed out of the
heart into the body and
the dub is the reloading
of the heart with more
blood ready to push it
out to the body
Dub
 The heart is made of cardiac muscle.
 When the cells receive an electrical
impulse they contract - causing a
heartbeat.
 Cardiac muscle is myogenic - it can
contract on its own, without needing nerve
impulses.
Major factors influencing blood
pressure
1. cardiac output: heart rate ( neural or
hormonal control)
2. Blood volume: regulating water content
of blood kidneys regulate blood volume
3. Resistance of Arteries to blood flow
 Hypotension = low BP
 Hypertention = high BP
The heart is actually a double pump with 2
separate circulatory systems
1. Pulmonary circulation: The short loop
pumped by the right ventricle from the
heart to the lungs and back to the heart
 Serves only to bring blood in contact with
alveoli resulting in gas exchange
 It does not meet the needs ( metabolic)
of the lung tissue
2. Systemic circulation:
 the many loops pumped by the left
ventricle through aorta, serving the whole
heart
Circulation Through the heart
 Aorta---arteries---capillaries---veins---vena
cavae—right atrium ---(thru tricuspid valve)
to----right ventricle---(thru pulmonary
semilunar valve) to---lung capillaries--pulmonary veins---left atrium---thru mitral
valve to ----left ventricle---(thru aortic
semilunar valve) back to----- aorta (to start
again)
Conduction system
 Cells in the heart beat as a unit due to the
intercalated disks which weaves the cell
endings together
 The orderly sequence of atrial and
ventricular contraction is maintained by an
intrinsic (internal) regulating system called
a conduction system
Conduction system
 This conduction system consists of
specialized muscle tissue which generates
and conducts electrical impulses to
stimulate the cardiac muscle to contract in
a cycle as a unit
 Consists of the S.A node and the A.V.
node
Sinoatrial node (SA node)
 This specialized node is found on the upper
inside wall of the right atrium.
 The SA node is known as the pacemaker of the
heart and initiates a heartbeat every 0.85
seconds.
 This signal travels across the atria causing them
to contract and load the ventricles with blood.
 Ventricles are electrically insulated from atria so they don’t contract yet.
Sinoatrial node ( S.A, node or
pacemaker)
Located in the right atrial wall
Initiate cardiac cycle ( sets the pace) by
sending impulses to both atria causing
them to contract…
This impulse also travels to the
atrioventricular node
Atrio-ventricular node (AV node)
 The AV node is located on the bottom surface of
the right atria and is responsible for initiating the
contraction of the ventricles.
 Electrical impulse passes to ventricles via AV
node and the Bundle of His. They pass the
impulse to the base of the ventricles (~ 0.1 s
delay).
 The bundle of His is a group of fibres that
conduct impulses to Purkyne fibres which carry
impulses to left & right ventricles.
 Ventricles then contract from the bottom
upwards.
Atrioventricular node (A.V.)
 Found on the septum (wall) between the
right atrium and right ventricle
 Sends impulses to the ventricles over a
bundle of branching conducting fibers
called the A.V. bundle ( bundle of his)
 These fibers keep branching until the
smallest make contact with cells in the
myocardium
Electrocardiograph
P = atrial systole
QRS = ventricular systole
T = ventricular diastole
 Q wave: absent on EKG. Necrosis (death
of an area of the heart muscle produces a
Q wave on EKG) used to diagnose heart
attack
 Myocardial infarction is usually related to
the left ventricle
 PR interval: problem in conduction system
( S.A node A.V node)
HOW TO READ EKG
 Determine the heart rate from EKG
1. First find a specific R wave that peaks on
a heavy line
2. Next count off 300, 150, 100, 75, 60, 50
for every thick line. Know these numbers
, you will use them
3. Where the next R wave falls determines
the rate
Ventricular fibrillation is an abnormal heart
rhythm that is disorganized and irregular.
Ventricular tachycardia is a rapid, regular
heart rhythm that originates in the lower
chambers of the heart.
Heart Facts
 Hold out your hand and make a fist. If you're a kid, your
heart is about the same size as your fist, and if you're an
adult, it's about the same size as two fists.
 Your heart beats about 100,000 times in one day and
about 35 million times in a year. During an average
lifetime, the human heart will beat more than 2.5 billion
times.
 Give a tennis ball a good, hard squeeze. You're using
about the same amount of force your heart uses to
pump blood out to the body. Even at rest, the muscles of
the heart work hard--twice as hard as the leg muscles of
a person sprinting.
circulation
William Harvey (1578-1657
 First described blood circulatory system in

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



humans
Used fish to figure out the flow of blood
Left ventricle holds 2 ounces of blood
Heart beats about 70 beats/minute
In one hr:
2 oz x 70 beats x 60 min = 84000 oz = 528
pounds of blood
Thus concluded blood must be reused
Vessels and routes
 Arteries: blood vessels which carry

1.
2.
3.
blood away from the heart
Arterial walls consist of 3 layers (
tunicas) around a hollow (lumen) tube
Tunica intima: internal lining
Tunica media: middle thickest tunica(
made of smooth muscle)
Tunica externa: tough outer coat that
acts as prtection
1
2
3
 Arterioles: small arteries
 Capillaries: microscopic blood vessels,
the walls of which consist of only a thin
layer of endothelium.
 Capillaries allow for the exchange of
nutrients, gases and waste to take place
by diffusion between blood plasma and
various tissue cells.
 Venules: small vessels that receive blood
from capillaries and merge into veins
 Veins: carry blood to the heart, have very
low pressure and valves
2 factors that assist venous blood
movement
1. Valves: veins have backflow preventing
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2.

valves
If faulty or leaky results in varicose
veins
Muscle contractions:
When muscles which surround the
veins ( especially arms and legs)
contract they squeeze the veins
pushing blood from valve to valve
varicose veins
 Pulse: the alternating expansion and
elastic recoil of the walls of an artery ( due
to ventricular systole and diastole)
 Pulse rate: heart rate = 70 to 80 per min
 Blood pressure: pressure (measured in
arteries) exerted by left ventricular systole
and remaining during diastole
 Average B.P. 120/80
 The difference between the 2 numbers is
a measure of the health of the artery
Hepatic Portal Circulation
 Blood enters liver from 2 sources:
1. The liver is supplied with oxygen rich blood by
hepatic artery ( not part of hepatic portal
system)
2. Veins drain the stomach, intestines, pancreas
etc… and merge into the hepatic portal vein
which brings this nutrient rich blood to the liver
for processing
 Blood leaves the liver by way of the hepatic
vein and enters the inferior vena cava
A prtal system is:
 Arteries—capillaries—veins—capillaries—
veins
 As opposed to normal:
 Artery—capillary --veins
Fetal circulation
 Differs from adults because lungs, kidneys
and GI tract are not functional
 Fetal and maternal blood does not mix
Key Differences in a fetus
1. Foramen ovale: hole between 2 atria, so
blood can bypass the right ventricle and
pulmonary circuit ( later closes leaving a
scar called the fossa ovalis)
2. Ductus arteriosus: vessel running from
pulmonary trunk to aorta, skipping
pulmonary circuit.
3. Umbilical arteries: 2 arteries which
branch off the internal iliacs carry
deoxygenated blood and waste to the
placenta
4. Umbilical vein: leaves placenta with
oxygenated blood heading toward fetal
heart, it bypasses the liver by way of the
ductus venosus ( which leads straight
into the inferior vena cava)
 Another modification involves fetal
hemoglobin
 It is slightly more attracted to oxygen than
is normal hemoglobin so fetus cant “steal”
moms oxygen