17.3 Flashcards
diameter of RBCs
7.5 micro meters
what is the purpose behind RBCs having structural proteins
allowing the RBC to deform yet spring back into shape
spectrin
maintains the biconcave shape of an erythrocytes
how is the small size and shape of an RBC significant
huge surface are relative to volume
how is the disc shape of an RBC significant
ideally suited for gas exchange, no point withing the cytoplasm is far from the surface
erythrocytes are over ____ hemoglobin
97%
what is the significance of RBCs lacking mitochondria
Because erythrocytes lack mitochondria and generate ATP by anaerobic mechanisms, they do not consume any of the oxygen they carry, making them very efficient oxygen transporters
Hemoglobin, the protein that makes red blood cells red, binds easily and ______ with _____ , and most oxygen carried in blood is bound to hemoglobin.
reversibly
oxygen
Normal values for hemoglobin are
13-18 g/100 ml in adult males
12-16 g/100 ml in adult females.
Hemoglobin is made up of the _____ bound to the ______
red heme pigment
protein globin
Globin consists of
4 polypeptide chains
2 alpha
2 beta
each polypeptide chain of the globin is bound to
a red ringlike heme group
Each heme group bears an
iron ion (Fe2+) set like a jewel in its center
A hemoglobin molecule can transport ____ molecules of oxygen because each ____ atom can combine reversibly with ____ molecule of ____
four
iron
one
oxygen
A single red blood cell contains about
_______ so each of these tiny cells can scoop up about ______
250 million hemoglobin molecules
1 billion molecules of oxygen
why is hemoglobin contained in erythrocytes
prevents it from leaking out of the plasma and clogging up the kidneys
Oxygen loading occurs in the ____, and the direction of transport is from ________. As oxygen-deficient blood moves through the lungs, oxygen diffuses from the air sacs of the lungs into the blood and then into the erythrocytes, where it binds to the iron in hemoglobin. The iron is partially oxidized by the oxygen. As a result, the protein, now called _____, assumes a new three-dimensional shape and becomes ruby red.
lungs
lungs to tissue cells
oxyhemoglobin
In body tissues, the process is reversed. Oxygen detaches from iron, hemoglobin resumes its former shape, and the resulting ________, or _______ becomes dark red. The released oxygen diffuses from the blood into the tissue fluid and then into tissue cells.
deoxyhemoglobin
reduced hemoglobin
About 20% of the carbon dioxide transported in the blood combines with hemoglobin, but it binds to _________ rather than to the heme group. This formation of _________occurs more readily when hemoglobin is in the reduced state. Carbon dioxide loading occurs in the _____, and the
direction of transport is from ____to ____, where carbon dioxide is eliminated from the body
globin’s amino acids
carbaminohemoglobin
tissues
tissues to lungs
Blood cell formation is referred to a
hematopoiesis
Hematopoiesis occurs in the
red bone marrow
the bone marrow is composed largely of a ___ bordering on wide blood capillaries called _________
soft network of reticular connective tissue
blood sinusoids
what is found in the reticular connective tissue network
macrophages, reticular cells, fat cells
On average, the marrow turns out an
ounce of new blood containing
100 billion new cells everyday
all the formed elements arise from
the hematopoietic stem cell, sometimes called a hemocytoblast
once a cell is committed to a specific blood cell pathway, it ______. This commitment is signaled by the appearance of membrane surface ______ that respond to specific hormones or growth factors, which in turn ____ the cell toward further specialization
cannot change
receptors
push
erythrocyte production is called
erythropoiesis
stages of erythropoiesis
Hematopoietic stem cell (hemocytoblast) Proerythroblast Basophilic erythroblast Polychromatic erythroblast Orthochromatic erythroblasts Reticulocyte Erythrocyte
what is the committed cell called
Proerythroblast
what are the 3 phases of the developmental pathway
1- ribosome synthesis
2- hemoglobin accumulation
3- ejection of nucleus
The entire process from hematopoietic stem cell to reticulocyte takes about
15 days
usually the erythrocytes become fully mature within how many days of their release into the bloodstream
2 days
as their ribosomes are degraded by intracellular enzymes.
Reticulocytes account for ____ of all erythrocytes in the
blood of healthy people.
1-2%
provide a rough index of the rate of RBC formation-reticulocyte counts below or above this range indicate abnormal rates of erythrocyte formation.
Reticulocyte counts
hypoxia is
oxygen deprivation
To ensure that the number of erythrocytes in blood remains within the homeostatic range, new cells are produced at the incredibly rapid rate of more than
2 million per second in healthy people
what are the 3 things that regulate erythropoiesis
iron
amino acids
certain B vitamins
a glycoprotein hormone, stimulates
the formation of erythrocytes
erythropoietin
which organ plays a major role in EPO production
kidneys and the liver kinda :)
When certain kidney cells become hypoxic
(oxygen deficient), oxygen-sensitive enzymes are unable to carry out their normal functions of degrading an
HIF hypoxia inducible factor
As HlF accumulates, it
accelerates the synthesis and release of
erythropoietin
The drop in normal blood oxygen levels that triggers EPO formation can result from:
low count of RBCs due to hemorrhage
excessive RBCs destruction
Insufficient hemoglobin/RBC (iron deficiency)
Reduced availability of O2 (high altitudes, Pneumonia)
Conversely, too many erythrocytes or excessive oxygen in
the bloodstream depresses
EPO production
Note that it is not the number of erythrocytes in blood that controls the rate of erythropoiesis. lnstead, control is
based on their ability
to transport enough oxygen to meet tissue demands.
Notice that hypoxia does not activate the bone marrow ____. Instead it stimulates the ____ , which in turn provide the hormonal stimulus that activates
the _____.
directly
kidneys
bone marrow
which type of athletes abuse EPO
professional bike racers and marathon runners seeking increased stamina and performance.
By injecting EPO, healthy athletes increase their normal
hematocrit from ___ to ___
45% to as much as 65%
why is EPO injecting dangerous
because during the race or whatever the blood concentrates even further and this may lead to clotting, stroke, or even heart failure
which hormone enhances EPO production
testosterone
The raw materials required for erythropoiesis include:
nutrients
2 B vitamin complex
Iron
which two vitamin B complex are we talking about
B12
Folic Acid
Free iron ions (Fe2+, Fe3+) are ___, so iron is
stored inside cells as protein-iron complexes such as ____ and _____
toxic
ferritin
hemosiderin
In blood, iron is transported loosely bound to a transport protein called _______, and developing erythrocytes take up iron as needed to
form hemoglobin
transferrin
lifespan of RBCs
100 to 120 days
old RBCs become trapped in __
the spleen and this is the reason behind it being called the RBC graveyard
the iron core of the heme group is __
bound to protein (as ferritin or
hemosiderin), and stored for reuse
The balance of the heme group is degraded to
bilirubin
a yellow pigment
that is released to the blood and binds to albumin for transport.
bilirubin
Liver cells pick up ____ and in turn secrete it in ____
into the intestine, where it is metabolized to ______. Most of this degraded pigment leaves the body in feces, as a brown pigment called _____.
bilirubin
bile
urobilinogen
stercobilin
The protein (globin) part of hemoglobin is metabolized or broken down to \_\_\_\_\_\_\_ which are released to the circulation.
amino acids
Most erythrocyte disorders can be classified as
anemia and polycythemia
anemia can be due to
blood loss
not enough RBC production
too many RBC destruction
is a condition in which
the blood’s oxygen-carrying capacity is too low to support
normal metabolism.
anemia
anemia is usually a ___ of some disorder
sign
what is the hallmark of anemia
blood oxygen levels that are
inadequate to support normal metabolism
describe anemia individuals
fatigued
pale
short of breath
chilled
blood loss anemia example
hemorrhagic anemia
what are the two types of hemorrhagic anemia
acute or chronic
describe blood loss of acute hemorrhagic anemia give example
rapid as in following being stabbed by a knife
treatment of acute hemorrhagic anemia
replace lost blood
what would be the reason behind chronic hemorrhagic anemia
due to hemorrhoids or an undiagnosed bleeding ulcer
describe blood loss of chronic hemorrhagic anemia
Slight but persistent blood loss
for chronic hemorrhagic anemia once the _____ is resolved normal erythropoietic mechanisms replace the lost blood cells.
primary problems
A number of problems can decrease erythrocyte production. These problems
range from
lack of essential raw materials (such as iron) to
complete failure of the red bone marrow
what is generally a secondary result of hemorrhagic anemia
iron deficiency anemia
iron deficiency anemia can also be a result of
inadequate intake of iron-containing foods
or unpaired iron absorption.
in iron deficiency anemia The erythrocytes produced under these conditions, called ______
are small and pale because they cannot synthesize their normal complement of hemoglobin.
microcytes
treatment for iron deficiency anemia
increase iron intake in diet or through iron supplements.
is an autoimmune disease that most often
affects the elderly.
Pernicious anemia
in Pernicious anemia The immune systern of these individuals destroys cells of
their own stomach mucosa
normally cells of the stomach muscosa proudce
intrinsic factors
intrinsic factors must be present for
vitamin B 12 to be absorbed by intestinal cells
Without vitamin B 12, the developing erythrocytes
grow but cannot divide
what does Pernicious anemia do to the cells
large, pale cells called macrocytes result
treatment for Pernicious anemia
regular intramuscular injections of vitamin B 12 or application of a B 12 containing gel to the nasal
lining once a week.
what can lack of vitamin B12 in a diet lead to
anemia
anemia due to lack of vitamin B12 is a problem for which group of people
strict vegetarians because meats, poultry, and fish provide ample vitamin B 12.
which anemia is caused by a lack of EPO
renal anemia
renal anemia frequently accompanies
renal diseases
treatment for renal anemia
administer EPO
anemia due to destruction of red bone marrow due to drugs, chemicals, radiation, virus is
aplastic anemia
for aplastic anemia that cause is usually
unknown
in aplastic anemia anemia is just a
sign because destruction of Red bone marrow will impair formation of all the formed elements presenting defects in blood clotting immunity
aplastic anemia treatment options
Blood transfusions provide a stopgap treatment until
stem cells harvested from a donor’s blood, bone marrow, or umbilical cord blood can be transplanted.
erythrocytes rupture, or lyse, prematurely.
hemolytic anemia
hemolytic anemia can be due to
Hemoglobin abnormalities, transfusion of mismatched blood,
and certain bacterial and parasitic infections are possible
causes
thalassemias are common in
people of Mediterranean ancestry
example of too many RBCs being destroyed
thalassemias and sickle cell anemia
in both thalassemias and sickle cell anemia the _____ part of hemoglobin is abnormal and the erythrocytes produced are ____ and ____
globin
fragile
rupture prematurely
what is the main problem in thalassemias
One of the globin chains is absent or faulty, and the erythrocytes are thin, delicate, and deficient in hemoglobin.
severe thalassemias require
monthly blood transfusions
Thalassemia protects these people from _____ due to the blood cells’ easy degradation.
malaria
In α thalassemia, production of the ______ is affected. The α globin chains are encoded by ___
closely linked genes _________. __ loci encode the α chain.
alpha globin chain
2
chromosome 16
4
In β thalassemia production of the _______ is affected. The β globin chains are encoded by a ____ gene on
_____. ___loci encode the β chain.
beta globin chain
single
chromosome 11
2
Deletion of one of the α loci has a high prevalence in people of _________ making them more likely to develop α thalassemia.
African or Asian descent,
Thalassemia is a group of
inherited (autosomal recessive) diseases
In autosomal recessive disease, ____ parents must be ____ for a child to be affected
both
carriers
in thalassemia there is ____ risk with each pregnancy for an affected child.
25%
60-80 million people in the world are carrying the beta thalassemia _____alone
trait
India and Pakistan are seeing a large increase of thalassemia patients due to
lack of genetic counseling and screening
which type of thalassemia does not require medical care or follow up
Mild thalassemia
Patients with β thalassemia trait should be warned about what
that their blood picture resembles iron deficiency and can be misdiagnosed.
what should patients with mild thalassemia avoid
empirical use of iron therapy
why is counselling important for people with thalassemia
Counseling is indicated in all persons with genetic disorders, especially when the family is at risk of a
severe form of disease that may be prevented
require medical treatment, and a blood transfusion regimen is effective in prolonging
life.
severe thalassemia
Medical therapy for β-thalassemia primarily involves
iron chelation
Medical therapy for β-thalassemia primarily involves iron chelation. The antioxidant can be incorporated into the redox machinery of β-thalassemic RBC and defend the cell from ____, possibly interfering with ______, a reactive intermediate in the hydroperoxide-dependent Hb degradation.
oxidation
perferryl-Hb
complications in thalassemia patients
iron overload infection bone deformities enlarged spleen slowed growth rates heart problems
People with thalassemia can get an overload of ___ in their bodies, either from the disease itself
or from frequent _______. Too much iron deposition can result in damage to the ___, ___and
_____, which includes glands that produce hormones that regulate processes throughout the body. Without iron chelation therapy, patients with beta-thalassemia will accumulate potentially ______.
iron
blood transfusions
heart, liver, and endocrine system
fatal iron levels
people with thalassemia have an increased risk of infection if the ____ has been removed as a
treatment.
spleen
Thalassemia can ___the bone marrow, causes bones to ____. This can result in abnormal
____, especially in the face and skull. Makes bones _____ increasing the risk of broken bones.
expand
widen
bone structure
thin and brittle
the spleen aids in fighting infection and filters unwanted material, such as old or damaged blood
cells. Thalassemia is often accompanied by the destruction of a large number of red blood cells, and the task of removing these cells causes the spleen to ____. _____can make anemia worse, and it can ____the life of transfused red blood cells. Severe enlargement of the spleen may necessitate its ____.
enlarge
splenomegaly
reduce
removal
anemia can cause a child’s growth to ___. ___also may be delayed in children with thalassemia.
slow
puberty
such as congestive heart failure and abnormal heart rhythms
(Arrhythmias) may be associated with
severe thalassemia.
In sickle-cell anemia, the havoc caused by the abnormal hemoglobin, ______ results from a change in just ______ in a ______chain of the ____ molecule
HbS
1 of the 146 amino acids
beta
globin
in sickle cell anemia This alteration causes the beta chains to link together under ______ forming _____
so that hemoglobin S becomes ______
low O2 conditoins
stiff rods
spiky and sharp
in sickle cell anemia it causes the red blood cells to become __________ when they
unload oxygen molecules or when the oxygen content of the blood is lower than normal, as during vigorous exercise and other activities that increase metabolic rate
crescent shaped
in sickle cell anemia
The stiff, deformed erythrocytes rupture easily and tend to jam up in small blood vessels. These events interfere with oxygen delivery, leaving the victims ________
gasping for air and in extreme pain
what follows up sickle cell anemia
Bone and chest pain are particularly severe, and infection and stroke often follow
______ is still the standard
treatment for an acute sickle-cell crisis, but preliminary results using _________ to dilate blood vessels are promising.
blood transfusions
inhaling nitric oxide
While individuals
with two copies of the sickle-cell gene have sickle-cell anemia, individuals \Vi th only one copy of the gene (sickle-cell
trait) have a
better chance of surviving malaria
____reduces the malaria
parasites’ ability to survive and enhances _____’ ability
to destroy infected RBCs and the parasites they contain.
sickling
macrophages
treatment for sickle cell is focused on
preventing cells from sickling
does fetal hemoglobin sickle
no even in those destined to have sickle cell anemia
___, a drug used to treat chronic leukemia, switches
the fetal hemoglobin gene back on
hydroxyurea
In children who are severely affected with sickle cell anemia , _______ offer a
complete cure, but carry high risks
bone marrow stem cell transplants
is an
abnormal excess of erythrocytes that increases blood viscosity,
causing it to flow sluggishly.
polycythemia
a bone marrow cancer, is characterized by dizziness and an exceptionally
high RBC count (8-l l million cells/µ!).
polycythemia vera
people with polycythemia vera The hematocrit may
be as high as ___ and blood volume may ____, causing the vascular system to become engorged with blood and severely
______
80%
double
impairing circulation
Severe polycythemia is treated by
removing some blood (a procedure called a therapeutic phlebotomy).
result when less oxygen is available or EPO production increases.
Secondary polycythernias
The secondary polycythemia
that appears in individuals living at high altitudes is a
normal physiological response to the reduced atmospheric pressure and
lower oxygen content of the air in such areas.
what is the count of RBC in people with secondary polycythemia
6-8 million/µL are common in such people.
practiced by some athletes competing in
aerobic events, is artificially induced polycythemia.
blood doping
Some of the athlete’s red blood cells are drawn off and stored. The body quickly replaces these erythrocytes because removing blood triggers the erythropoietin mechanism. Then, when the stored blood is reinfused a few days before the athletic event, _______
a temporary polycythemia results
Since red blood cells carry oxygen, the additional infusion should translate into increased oxygen-carrying capacity due to a higher hematocrit, and ______ should result. Other than the risk of ___and ____ due to high hematocrit and high blood viscosity, blood doping seems to work.
greater endurance and speed
stroke
heart failure
