Human Biology: Circulatory System
Lesson 2: Blood and the Lymphatic System
(Inquiry into Life pg. 226-230, 240-251)
Today’s Objectives
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Describe the components of blood, including:
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Describe the shape, function, and origin of red blood cells,
white blood cells, and platelets
List the major components of plasma
Explain the roles of antigens and antibodies
Describe the inter-relationships of the structures of the
lymphatic system, including:
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Describe the functions of the lymphatic system
Identify and give functions of lymph capillaries, veins, and
nodes
Components of Blood
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A) Plasma: 55% of blood
B) Formed Elements: 45% of blood
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Erythrocytes (Red Blood Cells)
Leukocytes (White Blood Cells)
Thrombocytes (Platelets)
FEATURE
RED BLOOD CELLS
SHAPE
Biconcave disc
FUNCTION
Transport O2
ORIGIN
ALSO CALLED
WHITE BLOOD CELLS
PLATELETS
Variable, Amoeboid
Tiny,
Cell fragments
Combat infection
Blood clotting
Bone marrow
Bone marrow
Lymphoid Tissue
Bone Marrow
Erythrocytes
Leukocytes
Thrombocytes
and
CO2
Constituents of Plasma
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NAME
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A. Water (90%)
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FUNCTION
Blood Volume
Transport of cells and materials
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B. Plasma Proteins
a) Albumen
b) Fibrinogen
c) Globulins
C. Gases
a) Oxygen
b) Carbon Dioxide
Helps maintain Osmotic pressure in blood.
-Transports
-Blood Clotting
-Infection fighting
-For respiration
-Waste
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D. Nutrients
a) A.A. Glucose,
Fatty acids, Glycerol
Energy source - Raw materials for the
body
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E. Salts
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Osmotic Pressure
Helps in Metabolism
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F. Wastes
Waste production of Cellular Reactions.
Shape, Function, and Origin of RBC
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Red Blood Cells (Erythrocytes)
Video
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Live about 120 days
Produced in Red Bone Marrow (in
skull, ribs, vertebrae, and long bones)
Myeloid stem cells form RBC
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These stem cells are called
Erythroblasts, which will differentiate
into Erythrocytes
Produce about 5 million/second
RBC contain a protein called
hemoglobin
Old RBC destroyed in the liver and
spleen
Hemoglobin
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Hemoglobin contains iron (gives its red color)
Picks up oxygen in the lungs then releases is it in the tissues
Approximately 200,000,000 hemoglobin molecules in one RBC
If hemoglobin was not packaged in RBC, oxygen would leak out of
the circulatory system
Shape, Function, and Origin of WBC
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White Blood Cells (Leukocytes)Video
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Larger than RBC
Have a nucleus (RBC do not)
Less numerous than RBC (700:1)
Do not have a definite shape
Function:
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Fights against infection in two ways:
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Phagocytosis
Produce Antibodies
Types of White Blood Cells
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Granular Leukocytes (Granulocytes)
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Have grains, or granules in their cytoplasm which are filled
with enzymes and proteins to fight against microbes
Formed in the bone marrow
60-70% of Leukocytes
Example: Neutrophil – phagocytize and digest bacteria
Agranular Leukocytes (Agranulocytes)
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No granules in cytoplasm
Produced by lymphatic tissue
25-30% of Leukocytes
Example: Monocytes (phagocytize pathogens and cellular
debris) and Lymphocytes (responsible for specific immunity)
Agranulocytes
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Monocytes:
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Largest WBC
Take up residence in tissues
Differentiate into larger ``macrophages`` which phagocytize
microbes and stimulate other WBC
Lymphocytes:
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B-Lymphocytes – produced in bone and lymphoid tissue
T-Lymphocytes – produced in the thymus and give rise to plasma
cells
Platelets (Thrombocytes)
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Blood Clotting:
Need three things in blood:
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2 billion produced/day
Broken fragments of larger cells
Very important in blood clotting
- Platelets
- Prothrombin
- Fibrinogen
1) Platelets clump at the site of the “leak” and partially
close it
2) Platelets and the injured tissue together release an
enzyme called Thromboplastin
Blood Clotting
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3) Thromboplastin converts a blood protein
(Prothrombin) into a new substance called Thrombin
4) Thrombin acts as an enzyme that breaks the ends off
another blood protein called Fibrinogen
5) Fibrinogen is then converted into Fibrin
6) Fibrin has sticky ends and forms a lattice or network
over the leak where blood cells get trapped, forming a
clot
7) Fibrin clot is only temporary – as soon as the blood
vessel repair is initiated, and enzyme called Plasmin
destroys the network
RBC trapped in the FIBRIN network
Lymphatic System (see video)
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Functions:
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1) Takes excess tissue fluid and sends it to the
circulatory system (lymphatic system joins
the circulatory system at the subclavian veins)
2) Products of fat digestion are absorbed into
Lacteals which lead to the Lymph vessels
and Nodes
3) Lymph nodes produce Lymphocytes (a type
of WBC) and help the body defend against
disease
4) Lymph nodes act as filters and trap
bacteria and other debris (helps to purify the
body fluids)
Lymphatic Structures
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Spleen:
Largest Lymphatic Tissue
Produces lymphocytes and stores excess blood
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If your blood pressure is high, stores blood so blood pressure
lowers
If your blood pressure is low, it contracts and squeezes out
blood, sending it back to the system so that blood pressure
rises
Thymus Gland:
Bi-lobed structure which is important
In the maturing of lymphocytes
Gets smaller as you age
Lymphatic Structures
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Tonsils and Appendix:
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Lymphatic Tissue:
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Similar to veins, but fluid only travels in one
direction (lymph veins and capillaries, but no
lymph arteries)
Lymph Nodes:
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Produce lymphocytes and stores excess blood
Lymph Vessels:
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Contain lymphoid tissue
Thought to help remove invading organisms
and viruses
Small oval or round tissues which filter fluids
and produce lymphocytes
Lacteals:
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Sacs in villi of digestive system which absorb
products of fat digestion
Infection Fighting – Inflammatory Response
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Foreign Substances (bacteria or viruses) attack
Monocytes and Neutrophils engulf the bacteria or
viruses in amoeboid fashion (phagocytosis)
These WBC are able to travel to the site of the
infection through capillary network
Dead tissue, cells, bacteria, dead and living neutrophils
all together make up Pus
Lymphocytes
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Produce antibodies
One antibody fights a specific antigen (foreign protein)
Antigen + Antibody inactive complex
Antigens:
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A protein found in the outer membrane of RBCs
Stimulate an immune response (production of antibodies)
The type of protein determines the blood type
Can also be a foreign protein introduced to the body
Antibodies:
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A protein found in the plasma
Attack unwanted proteins (bacteria or viruses)
End result is agglutination
ABO Blood System (see video)
Blood Group
Proteins on
Red Blood
Cells
(Antigen)
Clumping
Chemicals in
Plasma
(Antibody)
A
A
Anti B
A, O
B
B
Anti A
B, O
AB
A and B
None
A, B, AB, O
(universal
recipient)
O
None
Anti A Anti B
O
(universal donor)
Can Accept
Transfusions
from Group(s)
Rhesus Factor
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Red blood cells may have another antigen called antigen
D, known as the Rhesus Factor.
This distinguishes blood as being RH+ or RH-.
Therefore there are 8 possible blood types.