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Lecture 11

BIOB33H3 Lecture Notes - Lecture 11: Hemostasis, Right Coronary Artery, Circumflex Branch Of Left Coronary Artery


Department
Biological Sciences
Course Code
BIOB33H3
Professor
Connie Potroff
Lecture
11

Page:
of 6
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Lecture 11
The Cardiovascular System: Heart and Blood
**Assigned Readings: p.580 (fig 22.9) + p.593 (fig 22.20) –responsible for ALL
ARTERIES/VEINS in the diagrams!!!!
Introduction
The cardiovascular system functions as a system to transport numerous substances
throughout the body such as: nutrients, oxygen and carbon dioxide, hormones and
ions
Transports metabolic wastes to the kidneys
Transports leukocytes to aid in fighting infectious agents
Composition of the Blood
Whole blood 4-6 liters
Blood consists of two components
Plasma - liquid matrix of blood
Formed elements: blood cells and cell fragments that are suspended in
the plasma, and include:
Erythrocytes (red blood cells): transport oxygen and carbon dioxide
Leukocytes (white blood cells): function in the immune system
Platelets: involved in blood clotting
Plasma - makes up about 55% of the volume of whole blood
Consists of: 92% water
7% proteins (albumin, globulins, fibrinogen, regulatory proteins)
1% other solutes (electrolytes, organic nutrients, organic waste)
Plasma proteins: there are three major classes of protein in the blood
60% Albumin – contributes to the osmotic pressure, transports fatty acids
and steroids, smallest of the proteins
35% Globulins - act as immunoglobulins (antibodies) and act as transport
proteins (transport ions and hormones)
4% Fibrinogen - involved in blood clotting, largest of the proteins
Formed elements - makes up about 45% of whole blood
Platelets (<0.1% of formed elements)
Leukocytes (White Blood Cells WBC) (<0.1% of formed elements)
Neutrophils (5070% of the WBCs)
Eosinophils (2–4% of the WBCs)
Basophils (<1% of the WBCs)
Lymphocytes (20–30% of the WBCs)
Monocytes (2–8% of the WBCs)
Erythrocytes (Red Blood Cells RBC) (99.9% of formed elements)
Red Blood Cells (RBCs) or Erythrocytes
Structure of RBCs
Biconcave disc
Thin central region
Measure about 7.7 microns in diameter
Lack cell organelles
Lack a nucleus (anucleated)
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RBC Life Span
Since RBCs lack a nucleus and all the organelles, have a life span of
about 120 days
Significance of a lack of a nucleus:
Allows the cell to be flexible as it travels through the circulatory
system
Allows for more room for hemoglobin
Significance of a lack of mitochondria:
Mitochondria use oxygen to manufacture ATP
Without mitochondria, oxygen can be transported to the tissues
instead of being used by the mitochondria
RBCs and Hemoglobin
A developing erythrocyte loses its nucleus and organelles
A mature erythrocyte is mainly a cell membrane surrounding water and
protein
oThe water accounts for 66% of the RBC’s volume
oThe protein accounts for 33% of the RBC’s volume of which >95% is
hemoglobin
oHemoglobin is responsible for transporting oxygen and carbon dioxide (the
main function of RBCs)
Life Cycle of RBC
-finite lifespan of 120 days since no nucleus or cellular organs to repair itself or replace
damaged membrane regions – then phagocytized in spleen and stored in liver
-molecular components are broken down and recycled or eliminated from the body
-when RBC destroyed by macrophage in spleen, hemoglobin is recycled into heme and
globin
-**heme – the iron portion is transported in the blood by the protein transferrin and stored by
the protein ferritin in the liver ; the non-iron portion of heme gets converted into biliverdin
and then to bilirubin in the liver and is converted to pigments that are part of feces
-**globin is broken down into amino acids, some of which are used to make new RBCs
Hemoglobin
Consists of four polypeptide subunits
Each subunit contains a molecule of heme
Heme is a porphyrin ring
Each heme consists of an iron ion
oIron binds to oxygen
oThe polypeptide units bind to carbon dioxide
oOxygen and carbon dioxide do not compete with each other for binding sites
Leukocytes or White Blood Cells (WBCs)
There are two major classes of leukocytes consisting of a total of five
types of leukocytes
oGranulocytes: neutrophils, eosinophils, basophils
oAgranulocytes: monocytes, lymphocytes
WBCs have a short life span (usually a few days)
When the body is compromised, the white blood cells multiply to combat
the invading agent or allergen, etc.
oGranulocytes
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Neutrophils (normal range is 50–70%)
Granules contain chemicals to kill bacteria
Typically the first WBC at the bacterial site
Very active phagocytic cells
Nucleus is multi - lobed
**Eosinophils (normal range is 2–4%)
Granules release chemicals that reduce inflammation
Attack a foreign substance that has reacted with circulating
antibodies (such as an allergic reaction or parasites)
Typically have a bilobed nucleus
**Basophils (normal range less than 1%)
Granules release histamine and heparin
Histamine dilates blood vessels
**Heparin prevents abnormal blood clotting
Nucleus is usually hidden due to all the granules
oAgranulocytes
**Monocytes (normal range is 2–8%)
start as precursor cells in the blood and exit blood vessels move into
tissues where they then differentiate into macrophages (clean up debris,
eat damaged tissue, engulf bacteria, dead cells etc.)
Large phagocytic cells
Release chemicals to attract other phagocytic cells
Release chemicals to attract fibroblasts
Fibroblasts produce collagen fibers to surround an infected
site
These collagen fibers can produce scar tissue
Nucleus is kidney-shaped or large oval-shaped
Lymphocytes (normal range is 20–30%)
Responsible for specific immunity
Can differentiate to form T cells , B cells , and NK cells
Nucleus is typically large and round leaving a small halo
around the entire nucleus or part of it
T cells - attack foreign cells directly
B cells - antibodies to attack foreign cells
NK cells - Responsible for immune surveillance , attack abnormal and
infected tissue
oPlatelets
*Derived from megakaryocytes
Megakaryocytes will fragment forming bits and pieces of membrane-
enclosed packets of chemicals
The main chemical is platelet thromboplastin factor
About 350,000 per microliter of blood
Formerly called thrombocytes
Involved in blood clotting (hemostasis)
Release chemicals to initiate the clotting process (platelet thromboplastin