2. Objectives
At the end of this session, the learner will be able to:
• Define blood and list its functions
• Describe the composition, sites of production and functions of cellular parts of
blood and plasma
• Relate & explain the ABO blood groups & Rh factor.
• Describe the location, structure and functions of the heart and its great blood
vessels.
• Discuss the blood flow through the heart
• Describe the structure and functional features of the conducting system of the
heart.
3. Objectives
• Describe the principal events of a cardiac cycle.
• Explain the structure and function of:
– Arteries
– Veins & Capillaries
• Describe the following types of blood circulation:
– Pulmonary circulation
– Systemic circulation (coronary & hepatic portal
circulation).
4.
5. Blood
• The fluid connective tissue that circulates in the heart, arteries,
capillaries, and veins of a vertebrate animal carrying nourishment and
oxygen to and bringing away waste products from all parts of the body.
• Makes up about 8% of body weight (about 5.6 liters in 70kg man)
• This proportion is less in women and considerably greater in children,
gradually decreasing until the adult level is reached
• Blood in the blood vessels is always in motion because of pumping
action of the heart
6. Blood
• Composed of clear, straw colored, watery fluid
called plasma in which several different types of
blood cell are suspended
• Plasma constitutes 55% of blood volume
• Remaining 45% is accounted for cellular fraction
of blood
• Plasma and blood cells can be separated by
gravity, because cell are heavier than plasma
8. Blood Functions
Transportation: It transports oxygen from the lungs
to the tissues, and carbon dioxide from the tissue to
the lungs for excretion.
• It transports Nutrients from alimentary tract to the
tissue and cell wastes to the excretory organs
principally the kidneys.
• It transports Hormone secreted by endocrine glands
to their targeted glands and tissues.
9. Blood Functions
• It transport heat produced in active tissue to other
less active tissue.
• It transport protective substances e.g antibodies to
the area of infection.
• It transport Clotting factors that coagulate blood,
minimizing bleeding from ruptured blood vessels.
10. Blood Functions
Regulation: circulating blood helps maintains
homeostasis of all body fluids
• Blood also regulate PH through the use of
buffer
• It also adjust body temperature ( flow through
the skin, where excessive heat can be loss from
the blood to the environment.
12. Physical Characteristics of Blood
• Thicker than water
• 7-8 % of total body weight
• Blood volume
» 70 mL/kg of body weight
» 5 - 6 liters in males
» 4 - 5 liters in females
• Temperature - 100.40F
• pH - 7.35 to 7.45
13. Plasma
• Constituents of plasma are water (90-92%), and
dissolving and suspended substances including
– Plasma proteins (7%)
– Inorganic salts
– Nutrients, principally from digested food
– Waste materials
– Hormones
– Gases
14. Plasma proteins
Make up 7% of plasma
– Responsible for osmotic pressure (applied pressure to stop
osmosis) to keep blood within circulation
– Plasma viscosity is due to plasma protein mainly fibrinogen and
albumin
Albumin: (54%) formed in liver, main function is to maintain
osmotic pressure
– Albumin also acts as carrier molecule for lipids and steroid
hormones
15. Plasma proteins
• Globulins: (38%)main functions as
– antibodies (immunoglobulin) produced by lymphocytes
– Transportation of some hormones and mineral salts e.g.
thyroglobin carries the hormone thyroxine and transferrin
carries mineral iron
– Inhibition of some proteolytic enzymes e.g. alpha
macroglobulin inhibit trypsin activity
• Clotting factors: Fibrinogen(7%) is synthesis in liver and
essential for blood coagulation
16. Plasma
• Electrolytes: range of function
– Muscle contraction e.g. Calcium's
– Transmission of nerve impulses (potassium and sodium)
– Maintenance of acid base balance (phosphate)
• Nutrients
– The product of digestion e.g. glucose, amino acids, fatty
acid and glycerol are absorbed from alimentary tract
17. Plasma
• Waste product:
– Urea, creatanine and uric acid are the waste products of
protein metabolism formed in liver and carried in blood to
kidney for excretion
• Hormones:
– chemical messengers synthesized by endocrine glands
• Gases :
– Oxygen, carbon dioxide and nitrogen are transported round
the body dissolved in blood
18. Cellular content of blood
• Erythrocytes (Red Cells) 45% of blood
– Hemoglobin
• Leukocytes (White Cells)
– Granulocytes
• Neutrophils, eosinophils, and basophils
– Agranulocytes
• Monocytes and lymphocytes ( T and B lymphocytes)
• Platelets (Thrombocytes)
20. Red Blood Cells
• RBCs are biconcave
• Anucleated
• 7 micrometer in diameter
• Life span 120 days, then destroyed in spleen (graveyard of RBCs)
• Hemoglobin- quaternary structure, 2 chains and 2 chains.
• A normal RBC count would be: men – 4.7 to 6.1 million cells per
microlitre (cells/mcL) women – 4.2 to 5.4 million cells/mcL
• 1 RBC contains 280 million hemoglobin molecules
21. Red Blood Cells
Function-
Transport respiratory gases, mainly of oxygen but also carry
some carbon dioxide
Their biconcavity increase their surface area for gas
exchange and the thinness of central portion allow fast entry
and exit of gases
The cells are flexible, so they can squeeze through narrow
capillaries and contain no intracellular organelles and leave
more space for hemoglobin
23. Hemoglobin
• It is large complex protein containing a globular protien (globin)
and a pigmented iron containing complex called (Haem)
• Binds strongly, but reversibly, to oxygen
• Each hemoglobin molecule contain four globin chains and four
haem chains, each with one atom of iron: mean each hemoglobin
molecule can carry up to four molecules of oxygen
• An average red blood cell carries about 280 million hemoglobin
molecules.
• Normal hemoglobin in males: 13-18 g/dl & in female: 11.5-16.5
g/dl.
25. Leukocytes (White Blood Cells)
• Largest blood cell and Count only 1 % of blood volume
• Complete cells, with a nucleus and organelles
• Life span of WBC’s is 13 to 20 days.
• Function: important in defense and immunity
• Able to move into and out of blood vessels (diapedesis)
• Can move by ameboid motion
• Can respond to chemicals released by damaged tissues
26. Types of leukocytes
• Mainly two types
– Granulocytes ( Polymorphonuclear leukocytes)
• Neutrophils, Eosinophils and Basophils
– Agranulocytes
• Lack visible cytoplasmic granules
• Monocytes and lymphocytes
27. Granulocytes
• Neutrophils (60-70%)
– Multilobed nucleus with fine granules
– Act as phagocytes at active sites of infection
• Eosinophils (2-4%)
– Large brick-red cytoplasmic granules
– Found in response to allergies and parasitic worms
• Basophils (0.5-1.0%)
– Have histamine-containing granules
– Initiate inflammation
28. Agranulocytes
• Lymphocytes (20-25%)
– Large Nuclei, smaller than monocytes
– Play an important role in the immune response
• Monocytes(3-8%)
– Largest of the white blood cells
– Function as macrophages
– Important in fighting chronic infection
29. Significance of High and Low WBC
WBC Type
• Neutrophils
• Lymphocytes
High Count
• Bacterial infection,
burns, stress,
inflammation
• Viral infection,
leukemias
Radiation exposure,
drug toxicity, Vit B12
deficiency, SLE
Immuno-
suppression, Cortisol
use
Low Count
30. Significance of High and Low WBC
WBC Type
• Monocytes
• Eosinophils
• Basophils
High Count
• Viral or fungal infection,
TB, leukemia, chronic
disease
• Allergic reaction,
Parasitic infection,
autoimmune disease
• Allergic reaction, cancer,
hypothyroidism
Bone marrow
suppression, cortisol
use
Drug toxicity, stress
Pregnancy, ovulation,
hyperthyroidism
Low Count
31. Function of WBCs
• Scavenging: At the site of injury or infection,
neutrophils in blood and monocytes in the tissue engulf
worn out cells of the body and dead microbes and thus
act as scavengers.
• Diapedesis: Neutrophils show amoeboid movement. They
migrate towards the site of infection, squeeze through
capillary walls to engulf and kill microbes.
•
32. Function of WBCs
• Phagocytosis: On reaching site of infection, neutrophils and
monocytes engulf microbes or foreign matter or the damaged cells.
This is called phagocytosis. By phagocytosis, neutrophils kill
microorganisms and protect the body against infections.
• Inflammation or Inflammatory Reaction: Inflammation is
swelling caused at the site of injury. The blood vessels at this point
release more blood making it red and hot. Due to accumulation of
tissue fluid, the area swells up. The neutrophils and macrophages
migrate through capillary wall by diapedesis and fight against
invading microbes.
33. Function of WBCs
• Formation of Antibodies: Lymphocytes produce
antibodies to kill germs and neutralize their
toxins(poisons produced by bacteria).
• Confer Immunity: Lymphocytes also produce
antibodies to provide life long immunity against
certain diseases.
34. Platelets (thrombocytes)
• Small non nucleated disc 2-4 micrometers in
diameters
• Life span 8-11 days
• Function: promote blood clotting
• fall in platelets count, kidneys release a substance
called thrombopoieten which stimulate platelets
synthesis
38. Blood group
• Individuals have different types of antigen
(agglutinogen) on the surface of their RBCs
• These antigens are inherited, determine the
individual blood group
• Individual make antibodies to these antigens but
not to their own type of antigen, since if they did
the antigen, antibodies would react causing a
transfusion reaction which can be fatal
39. ABO BLOOD GROUP
• History
1. Landsteiners discovered the ABO Blood Group System
in 1901
2. He and five co-workers began mixing each others red
blood cells and serum together and accidentally
performed the first forward and reverse ABO
groupings.
3. About 55% of population have blood group A, blood
group B and blood group AB and remaining 45% have
blood group O
40. ABO BLOOD GROUP
• Blood groups are A,B,AB and O
• Person with Group A having Antigen A makes anti body B
• Person with Group B having Antigen B makes anti body A
• Person with Group AB having Antigen A and B and no
antibody
• Person with Group O neither A nor B antigen makes
antibodies A and B
41. Universal Donor and Recipient
• Group O have neither A and B antigens on RBCs,
may be safely transfused into A, B, AB and O is
known as the Universal Donor
• Blood group AB have neither A, nor B antibodies,
transfusion of either A, B , AB and O is likely to
be safe is known as Universal recipients
42. Major ABO Blood Group
ABO
Group
Antigen
Present
Antigen
Missing
Antibody
Present
A A B Anti-B
B B A Anti-A
O None A and B Anti-A&B
AB A and B None None
43.
44.
45.
46. The Rhesus system
• The red blood cell membrane antigen important
here is Rhesus (Rh) antigen or rhesus factor
• About 85% of people have this antigen, they are
rhesus positive and do not make their anti rhesus
antibodies
• The remaining 15% have no rhesus antigen, they
are rhesus negative
47.
48. Rh Dangers During Pregnancy
Danger is only when the mother is Rh–
and the father is Rh+, and the child
inherits the Rh+ factor
49. Rh Dangers During Pregnancy
The mismatch of an Rh– mother carrying an
Rh+ baby can cause problems for the
unborn child
The first pregnancy usually proceeds without
problems
The immune system is sensitized after the first
pregnancy
In a second pregnancy, the mother’s immune
system produces antibodies to attack the Rh+
blood (hemolytic disease of the newborn)
50.
51. Blood Vessels
• Blood is carried in a closed system of vessels that begins and
ends at the heart
• The three major types of vessels are arteries, capillaries,
and veins
• Arteries carry blood away from the heart
• Veins carry blood toward the heart
• Capillaries contact tissue cells and directly serve cellular
needs
53. Generalized Structure of Blood Vessels
• Arteries and veins are composed of three tunics
– –tunica adventitia or outer layer of fibrous tissue
– tunica media, middle layer of smooth muscle and elastic tissue
– tunica intima or inner lining of squamous epithelium
• Lumen – central blood-containing space surrounded by
tunics
55. Tunics
Tunica interna (tunica intima)
– Endothelial layer that lines the lumen of all vessels
Tunica media
– Smooth muscle and elastic fiber layer, regulated by
sympathetic nervous system
– Controls vasoconstriction/vasodilation of vessels
Tunica externa (tunica adventitia)
– Collagen fibers that protect and reinforce vessels
– Larger vessels contain vasa vasorum
56. Arteries
• Blood vessel that takes blood away from the heart
to all parts of the body (tissues, lungs, etc). Most
arteries carry oxygenated blood; the two
exceptions are the pulmonary and the umbilical
arteries, which carry deoxygenated blood to the
organs that oxygenate it.
57. Elastic (Conducting) Arteries
Thick-walled arteries - near the heart; the aorta and its major
branches
– Large lumen allow low-resistance conduction of blood
– Contain elastin in all three tunics
– Withstand and smooth out large blood pressure
fluctuations
– Allow blood to flow fairly continuously through the body
58. Muscular (Distributing) Arteries and
Arterioles
Muscular arteries – distal to elastic arteries; deliver blood to
body organs
– Have thick tunica media with more smooth muscle and
less elastic tissue
– Active in vasoconstriction
Arterioles – smallest arteries; lead to capillary beds
– Control flow into capillary beds via vasodilation and
constriction
59. Veins
• Veins are blood vessels that carry blood toward
the heart. Most veins carry deoxygenated blood from
the tissues back to the heart; exceptions are
the pulmonary and umbilical veins, both of which
carry oxygenated blood to the heart.
• The walls of veins are thinner than those of arteries
• The smallest veins are called venules
60. Capillaries
Capillaries - the smallest blood vessels
– The smallest arterioles break up into number of minute
vessels called capillaries
– Walls consist of single layer of endothelial cell sitting on
very thin membrane through which water and other small
molecule can pass
– Allow only a single RBC to pass at a time
62. Heart
• Cone shaped hollow muscular organ
• It is about 10-14 cm long, 9 cm wide and the size of
your fist.
• Its weight is 250 g in women and is heavier in men
(300 g).
• The heart lies in thoracic cavity in the mediastinum.
63. Heart Anatomy
• Location
– Superior surface of diaphragm
– Left of the midline
– Anterior to the vertebral column, posterior to the sternum.
– Base lies at 2nd intercostal space & apex at 5th intercostal
space.
• Structure
– Composed of three layers of tissue pericardium,
myocardium and endocardium
63
65. Heart layers
• Pericardium – a double-walled sac around the
heart composed of:
1. A superficial fibrous pericardium
2. A deep two-layer serous pericardium
a. The parietal layer lines the internal surface of the fibrous
pericardium
b. The visceral layer or epicardium lines the surface of the
heart
• They are separated by the fluid-filled pericardial cavity
called pericardial fluid: 25-35 ml.
65
66. Coverings of the Heart: Physiology
• The Function of the Pericardium:
– Protects and anchors the heart
– Prevents overfilling of the heart with blood
– Allows for the heart to work in a relatively
friction-free environment
68. Heart layers
• Myocardium
– Is composed of specialized cardiac muscle found
only in the heart
– Is involuntary
– Thickest layer of heart wall.
– The end branches of cell are close contact with
adjacent cell
69. Heart layers
• Endocardium:
– This lines the chambers and valves of the heart
– It is thin, smooth, glistening membrane that permits
smooth flow of blood inside the heart
– It consist of flattened epithelial cells and it is
continuous with the endothelium lining the blood
vessels
70. Actions of the Heart
Actions of the heart are classified into four types:
1. Chronotropic action----Heart Rate
2. Inotropic action.......Force of contraction
3. Dromotropic action.......Conduction of
impulse
4. Bathmotropic action.......Excitability of
muscles
72. Major Vessels of the Heart
• Vessels returning blood to the heart include:
1. Right and left pulmonary veins
2. Superior and inferior venae cavae
• Vessels conveying blood away from the heart
include:
1. Aorta
2. Right and left pulmonary arteries
72
76. Cardiac Chambers
• Human heart has 4 chambers
– 2 Atria
• Superior = primary receiving chambers, do not actually pump
• Blood flows into atria
– 2 Ventricles
• Pump blood
• Contraction = blood sent out of heart + circulated
• Chambers are separated by septum…
– Due to separate chambers, heart functions as double pump
77.
78. Atria of the Heart
• Atria are the receiving chambers of the heart
• Each atrium has a protruding auricle.
• Pectinate muscles are found in atria.
• Blood enters right atria from superior and
inferior venae cava and coronary sinus
• Blood enters left atria from pulmonary veins
Chapter 18, Cardiovascular System 78
79. Ventricles of the Heart
• Ventricles are the discharging chambers of the heart
• Papillary muscles and trabeculae carneae muscles
mark ventricular walls
• Right ventricle pumps blood into the pulmonary
trunk
• Left ventricle pumps blood into the aorta
Chapter 18, Cardiovascular System 79
80.
81.
82. Blood Flow Through Heart
• Blood flows into the Right Atrium from:
– Top half of the body via the Superior Vena Cava
– Bottom half of the body via the Inferior Vena Cava.
– From the heart via the Opening to the Coronary
Sinus.
• Coronary Sinus is the gathering point for deoxygenated
blood gathered by the cardiac veins.
83. Right Atrium
• In the right atrium you will see ridges of pectinate muscle.
• Also there is a blind pocket called the right auricle, which
is visible on from the anterior surface of the heart.
• When looking at the interatrial septum, (the wall between
the left and right atria), you will see the circular fossa
ovalis.
– The fossa ovalis is the remnant of the foramen ovalis, a hole that
allowed for blood flow between the left and right atria during
development in the womb.
84.
85. Right Atrium to Right Ventricle
• Blood passes from the right atrium to right ventricle
through a valve called the tricuspid valve.
• The chordae tendinae attach the tricuspid valve to
papillary muscles which causes the tricuspid valve
to close to prevent backflow.
86. Right Ventricle
• The right ventricle’s myocardium is not as thick as the left
ventricles.
• Remember the myocardium that forms a wall between the left
and right ventricles is called the interventricular septum.
• When the right ventricle contracts, blood is sent up through the
pulmonary trunk, which splits into the right and left
pulmonary arteries, the only arteries with deoxygenated blood
in them.
• Backflow is prevented by the pulmonary semilunar valve.
87. Lungs to Left Side of the Heart
• Oxygenated blood returns to the left atrium via the
left and right pulmonary veins.
• The valve between the left atrium and left ventricles
is called bicuspid valve.
• When the thick myocardium of the left ventricle
contracts it pushes blood up through the ascending
aorta.
88. Outflow
• Blood is prevented from backflow via aortic semilunar
valve.
• The first exits out the aorta are the openings to the
coronary arteries, which supply blood to the heart.
• The ascending aorta curves around to become the aortic
arch, which has three major arteries branching off before it
becomes the descending aorta.
– The branches are the brachiocephalic artery, left common
carotid artery, and left subclavian artery.
89. CORONARY CIRCULATION
• Heart is supplied by TWO CORONARY
arteries:
1- Right coronary artery---(RCA)
2- Left coronary artery---(LCA)
• These coronary arteries arise at the root of the
aorta.
90. Coronary arteries & their branches
Left coronary artery---- it passes under the left
atrium and divides into two branches:
1. Circumflex Artery
. It continues around the left side of the heart and
supplies blood to the left atrium and posterior
wall of the left ventricle.
2. Left Anterior Descending (LAD)
• It gives off smaller branches to the
interventricular septum and anterior walls of both
ventricles.
91. Right coronary artery ---- It gives off two
branches:
1. Marginal Artery
• It supplies blood to the lateral aspect of the
right atrium and ventricle.
2. Posterior descending artery
• It supplies blood to the posterior walls of both
ventricles.
92. Portal Circulation:
• The portal vein drains almost all of the blood from
the digestive tract and empties directly into the liver.
• This circulation of nutrient-rich blood between the
gut and liver is called the portal circulation.
• It enables the liver to remove any harmful substances
that may have been digested before the blood enters
the main blood circulation around the body—the
systemic circulation.
93.
94. Cardiac Cycle
Cardiac cycle consists of systole and diastole of
atria and ventricles
Atrial Systole (Atrial contraction):
• Lasts about 0.1 sec
• At the same time, the ventricles are relaxed
• Atrial depolarization causes atrial systole.
• Blood is forced via AV valves into the
ventricles.
95. Cardiac Cycle
• Atrial systole contributes 25 ml of blood to the
volume of 105 ml already in each ventricle.
• At the end of ventricular diastole, each
ventricle has 130 ml.
• This blood volume (120—130 ml) is called
end-diastolic volume (EDV).
• The percentage of the EDV ejected (about
60%) is ejection fraction.
96. Ventricular Systole:
• It lasts about 0.3 sec
• At the same time, the atria are relaxed.
• Ventricular depolarization causes ventricular systole.
• The right and left ventricles eject about 70 ml of blood
each into the pulmonary trunk and aorta respectively.
• The blood volume remaining in each ventricle at the
end of systole, about 60 ml, is the end-systolic volume
(ESV).
• Stroke volume (the volume ejected per beat by each
ventricle) equals EDV minus ESV (SV=EDV—ESV ).
97. • Cardiac Output: The amount of blood ejected by
each ventricle in one minute is called cardiac
output (CO).
• Cardiac output = Heart rate × Stroke volume
• Pre-load:
• Degree of tension on muscle when it begins to
contract
• Pre-load = end-diastolic pressure
• After-load: Load against which muscle exerts its
contractile force.
• After-load = pressure in aorta and pulmonary
trunk
98. Cardiac Cycle
• The average time required to complete the cardiac
cycle is usually less than one second (about 0.8
seconds at a heart rate of 75 beats/minute).
– 0.1 seconds – atria contract (atrial “kick”), ventricles are
relaxed
– 0.3 seconds – atria relax, ventricles contract
– 0.4 seconds – relaxation period for all chambers, allowing
passive filling. When heart rate increases, it’s this relaxation
period that decreases the most.
99. Cardiac Cycle
Valves
AV SL Outflow
Ventricular
diastole
Open Closed
Atrial
systole
Ventricular
systole
Closed Open
Early atrial
diastole
Ventricular
diastole
Open Closed
Late atrial
diastole
100. Heart Sounds
• The first sound (lubb) occurs as ventricle
contract & AV valve are closing.
• The second sound (Dupp) occurs as ventricle
relax & aortic & pulmonary valve are closing.
101. Path of Blood
Pulmonary Circuit
Blood flow between the
lungs and heart
Supplied by the Right side
of the heart
Systemic Circuit
Blood flow between the
rest of the body and heart
Supplied by the Left side
of the heart
102. Pulmonary Circulation
• In series with the systemic circulation.
• Receives 100% of cardiac output (3.5L/min/m2).
• RBC travels through lung in 4-5 seconds.
• 280 billion capillaries, supplying 300 million alveoli.
– Surface area for gas exchange = 50 – 100 m2
106. Conduction system of the heart
• The heart possesses the property of
autorythmicity which mean it generates its own
electrical impulses and beats independently of
nervous and hormonal control
• However it is supplied with both sympathetic and
parasympathetic nerve fibers which increase and
decrease respectively the intrinsic heart rate
107. Conduction system of the heart
• The heart responds to a number of circulating
hormones including adrenaline ( epinephrine) and
thyroxine
• Small groups of specialized neuromuscular cells
in the myocardium initiate and conduct the
impulses causing coordinated and synchronized
contraction of the heart muscle
108. Autorhythmic fibers: The Conduction system
• An inherent and rhythmical activity is the
reason for the heart life long beat
• The source of this electrical activity is a
network of specialized cardiac muscle fibers
called autorhythmic fiber because they are self
excitable
