STUDY GUIDE #5:
Blood (Chapter 18):
Functions of blood and know the functions within each category (Section 18.1)
Transportation
the transportation of nutrients, gases, and wastes throughout the body
Defense -WBCs to defend the body against infection and other threats;
Many types of protect the body from external threats, such as disease-causing bacteria that have entered the
bloodstream in a wound. Other WBCs seek out and destroy internal threats, such as cells with mutated DNA
that could multiply to become cancerous, or body cells infected with viruses.
Maintenance of Homeostasis the homeostatic regulation of pH, temperature, and other internal
conditions.
Composition of blood – plasma and formed elements, and their functions
Composition of Blood: It has four main components: plasma, red blood cells, white blood cells,
and platelets.
hematocrit- measures the percentage of RBCs, clinically known as erythrocytes, in a blood sample.
Function of erythrocytes and their relationship with hemoglobin-
The function of the red cell and its hemoglobin is to carry oxygen from the lungs or gills to all the
body tissues and to carry carbon dioxide, a waste product of metabolism, to the lungs, where
it is excreted.
erythrocyte = red blood cell (or RBC), is by far the most common formed element.
leukocytes (WBC) typically leave the blood vessels to perform their defensive functions, movement of
erythrocytes from the blood vessels is abnormal.
Figure 18.5 Summary of Formed Elements in Blood
Shape and Structure of Erythrocytes
Red blood cells are microscopic and have the shape of a flat disk or doughnut, which is round
with an indentation in the center, but it isn't hollow. Red blood cells don't have a nucleus like
white blood cells, allowing them to change shape and move throughout your body easier.
As an erythrocyte matures in the red bone marrow, an immature erythrocyte, known as a reticulocyte, will still
typically contain remnants of organelles.
Figure 18.6 Shape of Red Blood Cells Erythrocytes are biconcave discs with very shallow centers. This
shape optimizes the ratio of surface area to volume, facilitating gas exchange. It also enables them to fold up
as they move through narrow blood vessels.
Hemoglobin
Hemoglobin is a large molecule made up of proteins and iron. It consists of four folded chains of a protein
called globin, designated alpha 1 and 2, and beta 1 and 2 (Figure 18.7a). Each of these globin molecules is
bound to a red pigment molecule called heme, which contains an ion of iron (Fe2+) (Figure 18.7b).
Figure 18.7 Hemoglobin (a) A molecule of hemoglobin contains four globin proteins, each of which is bound
to one molecule of the iron-containing pigment heme. (b) A single erythrocyte can contain 300 million
hemoglobin molecules, and thus more than 1 billion oxygen molecules.
In the lungs, hemoglobin picks up oxygen, which binds to the iron ions, forming oxyhemoglobin. The bright
red, oxygenated hemoglobin travels to the body tissues, where it releases some of the oxygen molecules,
becoming darker red deoxyhemoglobin, sometimes referred to as reduced hemoglobin. About 23–24 percent
of it binds to the amino acids in hemoglobin, forming a molecule known as carbaminohemoglobin. Lower
percentages reflect hypoxemia, or low blood oxygen. The term hypoxia is more generic and simply refers to
low oxygen levels.
Erythrocyte disorders (Section 18.3)
Red blood cell (RBC) disorders are conditions that affect red blood cells, the cells of blood that carry
oxygen from the lungs to all parts of the body. There are many different types of red blood cell
disorders, including:
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anemia
red cell enzyme deficiencies (e.g. G6PD)
red cell membrane disorders (e.g. hereditary spherocytosis)
hemoglobinopathies (e.g. sickle cell disease and thalassemia)
hemolytic anemia
nutritional anemias (e.g. iron deficiency anemia, and folate deficiency)
disorders of heme production (e.g. sideroblastic anemia)
polycythemia (too many red blood cells)
hemochromatosis
Book version:
The size, shape, and number of erythrocytes, and the number of hemoglobin molecules can have a major
impact on a person’s health. When the number of RBCs or hemoglobin is deficient, the general condition is
called anemia.
Anemia can be broken down into three major groups: those caused by blood loss, those caused by faulty or
decreased RBC production, and those caused by excessive destruction of RBCs.
Anemias caused by faulty or decreased RBC production include sickle cell anemia, iron deficiency anemia,
vitamin deficiency anemia, and diseases of the bone marrow and stem cells.
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A characteristic change in the shape of erythrocytes is seen in sickle cell disease (also referred to as
sickle cell anemia). A genetic disorder, it is caused by production of an abnormal type of hemoglobin,
called hemoglobin S, which delivers less oxygen to tissues and causes erythrocytes to assume a sickle
(or crescent) shape, especially at low oxygen concentrations
Figure 18.9 Sickle Cells Sickle cell anemia is caused by a mutation in one of the hemoglobin genes.
Erythrocytes produce an abnormal type of hemoglobin, which causes the cell to take on a sickle or
crescent shape. (credit: Janice Haney Carr)
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Iron deficiency anemia is the most common type and results when the amount of available iron is
insufficient to allow production of sufficient heme. Vitamin-deficient anemias generally involve
insufficient vitamin B12 and folate.
Assorted disease processes can also interfere with the production and formation of RBCs and
hemoglobin. If myeloid stem cells are defective or replaced by cancer cells, there will be insufficient
quantities of RBCs produced.
o Aplastic anemia is the condition in which there are deficient numbers of RBC stem cells.
Aplastic anemia is often inherited, or it may be triggered by radiation, medication,
chemotherapy, or infection.
o Thalassemia is an inherited condition typically occurring in individuals from the Middle East, the
Mediterranean, African, and Southeast Asia, in which maturation of the RBCs does not proceed
normally. The most severe form is called Cooley’s anemia.
o Lead exposure from industrial sources or even dust from paint chips of iron-containing paints or
pottery that has not been properly glazed may also lead to destruction of the red marrow.
Various disease processes also can lead to anemias. These include chronic kidney diseases often
associated with a decreased production of EPO, hypothyroidism, some forms of cancer, lupus, and
rheumatoid arthritis.
In contrast to anemia, an elevated RBC count is called polycythemia and is detected in a patient’s elevated
hematocrit. It can occur transiently in a person who is dehydrated; when water intake is inadequate or water
losses are excessive, the plasma volume falls. As a result, the hematocrit rises.
Structure/classification and function of leukocytes
Characteristics of Leukocytes
A white blood cell, also known as a leukocyte or white corpuscle, is a cellular component of the
blood that lacks hemoglobin, has a nucleus, is capable of motility, and defends the body
against infection and disease.
Although leukocytes and erythrocytes both originate from hematopoietic stem cells in the bone marrow, they
are very different from each other in many significant ways. For instance, leukocytes are far less numerous
than erythrocytes: For leukocytes, the vascular network is simply a highway they travel and soon exit to reach
their true destination. When they arrive, they are often given distinct names, such as macrophage or microglia,
depending on their function. As shown in Figure 18.10, they leave the capillaries—the smallest blood
vessels—or other small vessels through a process known as emigration (from the Latin for “removal”)
or diapedesis (dia- = “through”; -pedan = “to leap”) in which they squeeze through adjacent cells in a blood
vessel wall.
This attracting of leukocytes occurs because of positive chemotaxis (literally “movement in response to
chemicals”), a phenomenon in which injured or infected cells and nearby leukocytes emit the equivalent of a
chemical “911” call, attracting more leukocytes to the site.
Classification of Leukocytes
When scientists first began to observe stained blood slides, it quickly became evident that leukocytes could be
divided into two groups, according to whether their cytoplasm contained highly visible granules:
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Granular leukocytes contain abundant granules within the cytoplasm. They include neutrophils,
eosinophils, and basophils (you can view their lineage from myeloid stem cells in Figure 18.4).
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While granules are not totally lacking in agranular leukocytes, they are far fewer and less obvious.
Agranular leukocytes include monocytes, which mature into macrophages that are phagocytic, and
lymphocytes, which arise from the lymphoid stem cell line.
Granular Leukocytes
We will consider the granular leukocytes in order from most common to least common. All of these are
produced in the red bone marrow and have a short lifespan of hours to days. They typically have a lobed
nucleus and are classified according to which type of stain best highlights their granules (Figure 18.11).
Figure 18.11 Granular Leukocytes A neutrophil has small granules that stain light lilac and a nucleus with two
to five lobes. An eosinophil’s granules are slightly larger and stain reddish-orange, and its nucleus has two to
three lobes. A basophil has large granules that stain dark blue to purple and a two-lobed nucleus.
The most common of all the leukocytes, neutrophils will normally comprise 50–70 percent of total leukocyte
count. The granules are numerous but quite fine and normally appear light lilac. The nucleus has a distinct
lobed appearance and may have two to five lobes, the number increasing with the age of the cell.
Older neutrophils have increasing numbers of lobes and are often referred to as polymorphonuclear (a
nucleus with many forms), or simply “polys.” Younger and immature neutrophils begin to develop lobes and are
known as “bands.”
Neutrophils are rapid responders to the site of infection and are efficient phagocytes with a preference for
bacteria. Their granules include lysozyme, an enzyme capable of lysing, or breaking down, bacterial cell walls;
oxidants such as hydrogen peroxide; and defensins, proteins that bind to and puncture bacterial and fungal
plasma membranes, so that the cell contents leak out. Abnormally high counts of neutrophils indicate infection
and/or inflammation, particularly triggered by bacteria, but are also found in burn patients and others
experiencing unusual stress.
Eosinophils typically represent 2–4 percent of total leukocyte count. They are also 10–12 µm in diameter. The
granules of eosinophils stain best with an acidic stain known as eosin.
Basophils are the least common leukocytes, typically comprising less than one percent of the total leukocyte
count.
Agranular Leukocytes
Agranular leukocytes contain smaller, less-visible granules in their cytoplasm than do granular leukocytes. The
nucleus is simple in shape, sometimes with an indentation but without distinct lobes
Lymphocytes are the only formed element of blood that arises from lymphoid stem cells.
The three major groups of lymphocytes include natural killer cells, B cells, and T cells. Natural killer (NK)
cells are capable of recognizing cells that do not express “self” proteins on their plasma membrane or that
contain foreign or abnormal markers.
B cells and T cells, also called B lymphocytes and T lymphocytes, play prominent roles in defending the
body against specific pathogens (disease-causing microorganisms) and are involved in specific immunity.
A memory cell is a variety of both B and T cells that forms after exposure to a pathogen and mounts rapid
responses upon subsequent exposures. Unlike other leukocytes, memory cells live for many years.
Monocytes originate from myeloid stem cells.
Leukocyte disorders (Section 18.4)
Leukopenia is a condition in which too few leukocytes are produced. If this condition is pronounced, the
individual may be unable to ward off disease. Excessive leukocyte proliferation is known as leukocytosis.
Although leukocyte counts are high, the cells themselves are often nonfunctional, leaving the individual at
increased risk for disease.
Leukemia is a cancer involving an abundance of leukocytes. It may involve only one specific type of leukocyte
from either the myeloid line (myelocytic leukemia) or the lymphoid line (lymphocytic leukemia). In chronic
leukemia, mature leukocytes accumulate and fail to die. In acute leukemia, there is an overproduction of
young, immature leukocytes. In both conditions the cells do not function properly.
Lymphoma is a form of cancer in which masses of malignant T and/or B lymphocytes collect in lymph nodes,
the spleen, the liver, and other tissues. As in leukemia, the malignant leukocytes do not function properly, and
the patient is vulnerable to infection. Some forms of lymphoma tend to progress slowly and respond well to
treatment. Others tend to progress quickly and require aggressive treatment, without which they are rapidly
fatal.
Platelets
platelets
(also, thrombocytes) one of the formed elements of blood that consists of cell fragments broken off from
megakaryocytes
Total WBC count versus differential WBC count
A white blood cell (WBC) count measures the number of white blood cells in your blood, and a WBC
differential determines the percentage of each type of white blood cell present in your blood. A
differential can also detect immature white blood cells and abnormalities, both of which are signs of
potential issues.
The Heart (Chapter 19):
Difference between pulmonary and systemic circuits
The pulmonary circuit transports blood to and from the lungs, where it picks up oxygen and delivers carbon
dioxide for exhalation. The systemic circuit transports oxygenated blood to virtually all of the tissues of the
body and returns relatively deoxygenated blood and carbon dioxide to the heart to be sent back to the
pulmonary circulation.
Basic structures of the heart and the great vessels
Four major heart valves, coverings, associated structures, and their function:
Right Atrium
The right atrium serves as the receiving chamber for blood returning to the heart from the systemic
circulation. The two major systemic veins, the superior and inferior venae cavae, and the large
coronary vein called the coronary sinus that drains the heart myocardium empty into the right
atrium. The
Right Ventricle
The right ventricle receives blood from the right atrium through the tricuspid valve. Each flap of the
valve is attached to strong strands of connective tissue, the chordae tendineae, literally “tendinous
cords,” or sometimes more poetically referred to as “heart strings.” There
Left Atrium
After exchange of gases in the pulmonary capillaries, blood returns to the left atrium high in oxygen
via one of the four pulmonary veins. While
Left Ventricle
Recall that, although both sides of the heart will pump the same amount of blood, the muscular layer
is much thicker in the left ventricle compared to the right
Between the right atrium and the right ventricle is the right atrioventricular valve, or tricuspid
valve. It typically consists of three flaps, or leaflets, made of endocardium reinforced with additional
connective tissue.
Emerging from the right ventricle at the base of the pulmonary trunk is the pulmonary semilunar
valve, or the pulmonary valve; it is also known as the pulmonic valve or the right semilunar valve.
Located at the opening between the left atrium and left ventricle is the mitral valve, also called the
bicuspid valve or the left atrioventricular valve.
At the base of the aorta is the aortic semilunar valve, or the aortic valve, which prevents backflow
from the aorta.
Blood flow through the heart:
Superior/inferior vena cava - right atrium - tricuspid valve - right ventricle - pulmonary
semilunar valve - pulmonary trunk - pulmonary arteries - lungs - pulmonary veins - left atrium
- bicuspid valve - left ventricle - aortic semilunar valve - ascending aorta - aortic arch descending aorta
Coronary vessels
Coronary arteries are the blood vessels that supply oxygen-rich blood to your heart muscle to
keep it pumping. The coronary arteries are directly on top of your heart muscle. You have four main
coronary arteries: The right coronary artery. The left coronary artery. The left anterior descending
artery. The left circumflex artery
​Surface Features of the Heart
Inside the pericardium, the surface features of the heart are visible, including the four chambers.
There is a superficial leaf-like extension of the atria near the superior surface of the heart, one on
each side, called an auricle—a name that means “ear like”—because its shape resembles the
external ear of a human (Figure 19.6). Auricles are relatively thin-walled structures that can fill with
blood and empty into the atria or upper chambers of the heart. You may also hear them referred to as
atrial appendages. Also prominent is a series of fat-filled grooves, each of which is known as a sulcus
(plural = sulci), along the superior surfaces of the heart. Major coronary blood vessels are located in
these sulci. The deep coronary sulcus is located between the atria and ventricles. Located between
the left and right ventricles are two additional sulci that are not as deep as the coronary sulcus. The
anterior interventricular sulcus is visible on the anterior surface of the heart, whereas the posterior
interventricular sulcus is visible on the posterior surface of the heart. Figure 19.6 illustrates anterior
and posterior views of the surface of the heart.
Ailments of the heart:
Heart diseases include:
● Blood vessel disease, such as coronary artery disease.
● Heart rhythm problems (arrhythmias)
● Heart defects you're born with (congenital heart defects)
● Heart valve disease.
● Disease of the heart muscle.
● Heart infection.
Cardiac tamponade-excess fluid builds within the pericardial space, it can lead to a condition called
cardiac tamponade, or pericardial tamponade.
Incompetent valve- When heart valves do not function properly, they are often described as
incompetent and result in valvular heart disease, which can range from benign to lethal. Valvular
disorders are often caused by carditis, or inflammation of the heart. One common trigger for this
inflammation is rheumatic fever, or scarlet fever, an autoimmune response to the presence of a
bacterium, Streptococcus pyogenes, normally a disease of childhood.
Angina pectoris- In the case of acute Myocardial infarction (MI), there is often sudden pain beneath
the sternum (retrosternal pain) called anginapectoris, often radiating down the left arm in males but
not in female patients. Until
Blood Vessels (Chapter 20):
Which vessels carry which type of blood (oxygenated versus deoxygenated):
Arteries carry oxygenated blood.
Veins carry deoxygenated blood
Basic structure of blood vessel walls (including the tunics)
The tunica intima (also called the tunica interna) is composed of epithelial and connective tissue
layers.
The tunica media is the substantial middle layer of the vessel wall (see Figure 20.3). It is generally
the thickest layer in arteries, and it is much thicker in arteries than it is in veins.
The outer tunic, the tunica externa (also called the tunica adventitia), is a substantial sheath of
connective tissue composed primarily of collagenous fibers. Some bands of elastic fibers are found
here as well.
Elastic versus muscular arteries:
elastic artery: those close to the heart have the thickest walls, containing a high percentage of
elastic fibers in all three of their tunics.
muscular arteries branch to distribute blood to the vast network of arterioles. For this reason, a
muscular artery is also known as a distributing artery.
Capillary beds: Each metarteriole arises from a terminal arteriole and branches to supply blood to a
capillary bed that may consist of 10–100 capillaries.
Veins and valves: A vein is a blood vessel that conducts blood toward the heart.
valves formed by sections of thickened endothelium that are reinforced with connective tissue,
extending into the lumen.
Function of arteries, veins, and capillaries
An artery is a blood vessel that conducts blood away from the heart. All arteries have relatively thick
walls that can withstand the high pressure of blood ejected from the heart.
A vein is a blood vessel that conducts blood toward the heart. Compared to arteries, veins are
thin-walled vessels with large and irregular lumens (see
A capillary is a microscopic channel that supplies blood to the tissues, a process called perfusion.
Exchange
Major arteries and veins of the body – those that are studied in your lab homework
Hepatic portal system:
specialized circulatory pathway that carries blood from digestive organs to the liver for processing
before being sent to the systemic circulation
Varicose veins: This disorder arises when defective valves allow blood to accumulate within the veins,
causing them to distend, twist, and become visible on the surface of the integument. Varicose veins
may occur in both sexes, but are more common in women and are often related to pregnancy. More
than simple cosmetic blemishes, varicose veins are often painful and sometimes itchy or throbbing.
Vein most commonly used for blood draws:
Median cubital vein
The Lymphatic System (Chapter 21):
Function of lymphatic vessels:
Lymphatic vessels are the network of capillaries (microvessels) and a large network of tubes located
throughout your body that transport lymph away from tissues. Lymphatic vessels collect and filter
lymph (at the nodes) as it continues to move toward larger vessels called collecting ducts.
A major function of the lymphatic system is to drain body fluids and return them to the bloodstream. Blood
pressure causes leakage of fluid from the capillaries, resulting in the accumulation of fluid in the interstitial
space—that is, spaces between individual cells in the tissues.
As the vertebrate immune system evolved, the network of lymphatic vessels became convenient avenues for
transporting the cells of the immune system. Additionally, the transport of dietary lipids and fat-soluble vitamins
absorbed in the gut uses this system.
Cells of the immune system not only use lymphatic vessels to make their way from interstitial spaces back into
the circulation, but they also use lymph nodes as major staging areas for the development of critical immune
responses. A lymph node is one of the small, bean-shaped organs located throughout the lymphatic system.
afferent lymphatic vessels= leads into a lymph node
efferent lymphatic vessels= leads out of a lymph node
Drainage order of the specific lymphatic vessels
The overall drainage system of the body is asymmetrical (see Figure 21.4). The right lymphatic duct
receives lymph from only the upper right side of the body. The lymph from the rest of the body enters
the bloodstream through the thoracic duct via all the remaining lymphatic trunks. In general, lymphatic
vessels of the subcutaneous tissues of the skin, that is, the superficial lymphatics, follow the same
routes as veins, whereas the deep lymphatic vessels of the viscera generally follow the paths of
arteries.
Which parts of the body drain into which major lymphatic vessels
The Thoracic Duct: The majority of the body (bilateral lower extremities, pelvis, lower and left
abdomen, left arm, neck and cranium
Right Lymphatic duct: Less of the body drains into this section which includes: right mid-abdomen,
right thoracic region, right arm, neck and cranium
Functions of the lymphatic system
The main roles of the lymphatic system include:
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managing the fluid levels in the body.
reacting to bacteria.
dealing with cancer cells.
dealing with cell products that otherwise would result in disease or disorders.
absorbing some of the fats in our diet from the intestine.
The lymphatic system has three functions:
● The removal of excess fluids from body tissues. ...
● Absorption of fatty acids and subsequent transport of fat, chyle, to the circulatory system.
● Production of immune cells (such as lymphocytes, monocytes, and antibody producing cells
called plasma cells).
A major function of the lymphatic system is to drain body fluids and return them to the bloodstream.
Blood pressure causes leakage of fluid from the capillaries, resulting in the accumulation of fluid in
the interstitial space—that is, spaces between individual cells in the tissues.
Function of organs contained in the lymphatic system, including MALT and thymus-
The major routes into the lymph node are via afferent lymphatic vessels. Cells and lymph fluid that
leave the lymph node may do so by another set of vessels known as the efferent lymphatic vessels.
the spleen is a major secondary lymphoid organ-the “filter of the blood” because of its extensive
vascularization and the presence of macrophages and dendritic cells that remove microbes and other
materials from the blood, including dying red blood cells. The spleen also functions as the location of
immune responses to blood-borne pathogens.
lymphoid nodules, have a simpler architecture than the spleen and lymph nodes in that they consist
of a dense cluster of lymphocytes without a surrounding fibrous capsule. These nodules are located
in the respiratory and digestive tracts, areas routinely exposed to environmental pathogens.
Tonsils are lymphoid nodules located along the inner surface of the pharynx and are important
in developing immunity to oral pathogens
Mucosa-associated lymphoid tissue (MALT) consists of an aggregate of lymphoid follicles directly
associated with the mucous membrane epithelia. MALT makes up dome-shaped structures found
underlying the mucosa of the gastrointestinal tract, breast tissue, lungs, and eyes. Peyer’s patches, a
type of MALT in the small intestine, are especially important for immune responses against ingested
substances
Function of lymphocytesLymphocytes are white blood cells uniform in appearance but varied in function and include T, B, and
natural killer cells. These cells are responsible for antibody production, direct cell-mediated killing
of virus-infected and tumor cells, and regulation of the immune response.
Leukocytes function in body defenses.
lymphocytes, which are critical to the body’s defense against specific threats. Leukemia and
lymphoma are malignancies involving leukocytes. Platelets are fragments of cells known as
megakaryocytes that dwell within the bone marrow. While many platelets are stored in the spleen,
others enter the circulation and are essential for hemostasis; they also produce several growth factors
important for repair and healing.
which specifically coordinate the activities of adaptive immunity
Helper T cells, or Th cells, coordinate immune responses by communicating with other cells.
In most cases, T cells only recognize an antigen if it is carried on the surface of a cell by one
of the body's own MHC, or major histocompatibility complex, molecules.