Physiology of Erythrocytes 1 Flashcards by Rafeea AlKaabi

True or False: Erythrocytes are flattened discs with depressed centers

True

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The unique shape of erythrocytes contributes to their main function of?

Oxygen transport in the blood

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The features of RBCs that help facilitate its main function of O2 transport are:
Biconcave Shape:
Thinness of the cell:
Flexibility of the membrane:
Explain the three.

Biconcave Shape: Larger surface area for O2 diffusion
Thinness of the cell: Rapid O2 diffusion between the exterior and innermost regions of the cell
Flexibility of the membrane: Deform and squeeze (which helps it travel through narrow and convoluted capillaries)

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Hemoglobin is a —– found in erythrocytes and consists of 2 portions.
Name the 2 portions and describe them.

Pigment
Globin portion: protein, four folded polypeptide chains
Heme portion: four iron-containing groups

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Hemoglobin can bind up to —– oxygen molecules.
The binding of oxygen to hemoglobin follows the law of?

Four
Law of mass action

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Binding of oxygen to hemoglobin has a ——— relationship, and is enhanced by ———-.

Non-linear
Positive cooperativity

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Positive cooperatively means

The binding of the first oxygen facilitates the binding of the second and so on

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Saturation of hemoglobin is a measure of?
100% saturation means that?

How much oxygen is bound to hemoglobin
All four binding sites have oxygen bound to them

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In arterial blood: Hemoglobin is —% saturated, and where is the remaining —%?
In venous blood: Hemoglobin is —% saturated, and what does that number indicate?

98.5%, remaining 1.5% dissolved in plasma
75%, indicates that only three binding sites are bound, and the missing one has been used in the tissue

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Hemoglobin and Carbondioxide:
1. The —- effect.
2. CO2 reacts with hemoglobin to form —–.
3. The reaction is reversible/irreversible.

Carbamino effect
Carbaminohemoglobin
Reversible

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Hemoglobin can function as a —– by binding to excess —– in a reversible/irreversible reaction.
The product of this binding is called ——– and has a greater/lesser affinity for H+.

buffer, H+ ions, reversible
Deoxyhemoglobin, greater

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Carbon monoxide is called the silent killer.
Compared to oxygen, does hemoglobin have a greater or lower affinity for carbon monoxide?

Greater affinity for CO

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The affinity of hemoglobin for CO is — times larger than its affinity for O2, so CO —- oxygen from binding to ——.

240x, prevents, hemoglobin

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Carbon monoxide reacts with hemoglobin to form ——, in a reversible/irreversible reaction.

Carboxyhemoblobin, irreversible

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Nitric Oxide (NO), is a —- that binds to —– in the lung.
RXN: Hb -> SNO

vasodilator, sulfur

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When NO is released in the tissues it —— local arterioles, which —— blood and O2 supply.

dilates, increases

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NO — blood pressure.

stabilizes

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How does NO stabilize blood pressure?

When the BP increases, NO is released, which increases the diameter of the lumen of blood vessels. The dilation results in the decrease of blood pressure.

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True or false: Erythrocytes are mainly plasma membrane-enclosed sacs full of CO.

False, Hb*

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A single erythrocyte contains more than 250 million Hb.
It contains no —-, —-, or —-, so it does not have —- and —–.

nucleus, organelles, ribosomes, DNA, RNA

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Since erythrocytes have no DNA and RNA they cannot ————- for cellular repair, growth, or division, which makes them ——-.

synthesize proteins, short-lived

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RBCs survive only 120 days and must be —— at the average rate of —–million/s.

replaced, 2-3

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The two erythrocyte enzymes are —– and ——.

Glycolytic enzymes, Carbonic anhydrase (CA)

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Glycolytic enzymes are used by RBCs for ——-, which is required for ——–.

ATP production, O2 transport to all tissues

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The glycolytic enzymes are:

Hexokinase, pyruvate kinase, phosophofructokinase

Carbonic anhydrase (CA) is critical for ----- transport in the form of -----(90%).

CO2, HCO-3 (bicarbonate) RXN: CO2 + H2O<-CA->H2CO3<-->H+ + HCO-3

Erythropoiesis is the production of -------; it happens in the --------.

Erythrocytes, bone marrow

All blood cells start off as a ------, called a hemocytoblast. In erythropoiesis, a hemocytoblast then becomes a --------, called a proerythroblast.

Stem cell, committed cell

A proerythroblast differentiates into an ---------, and then to a --------.

early erythroblast, late erythroblast

Main feature of the early erythroblast is that it produces a huge number of -------, which stains the cell ------.

ribosomes, blue

The main feature of late erythroblasts is:

synthesis of Hb, which stains the cytoplasm red, and accumulation of iron

A late erythroblast differentiates into a ------.

normoblast

Main features of a normoblast are:

1. The ejection of all its organelles after all Hb has been accumulated 2. Achieves its biconcave shape; end of nuclear function and the cell collapses forming its final shape

A normoblast differentiates into a -------.

reticulocyte

Reticulocytes are also called ------. They have a scant reticulum network of clustered -----, and these ----- are degraded by intracellular ------ within --- days.

young erythrocytes, ribosomes, ribosomes, enzymes, 2

True or false: Reticulocytes enter the bloodstream to begin O2 transport and become mature within 2 days.

True

Reticulocyte counts in healthy people are -----% of all erythrocytes. Any increase of decrease denotes an abnormality in ------ formation.

1-2% erythrocyte

Scenario: A patient in the ER has an abnormally low RBC count. Which structure is most likely damaged?

Bone marrow

The process of erythropoiesis takes about ---- days.

Areas of the body that produce erythrocytes: ----- bones produce red blood cells until a person is 5 years old

All

Areas of the body that produce erythrocytes: ----- bones become fatty and produce no more erythrocytes after the age 20.

Long bones, exception: proximal portions of the humeri and tibiae

Areas of the body that produce erythrocytes: At ---- years old, most erythrocytes continue to be produced in the vertebrae, sternum, ribs, and iliac. Even in these bones, the marrow becomes less production as --------.

>20 age increases

Which organ detects reduced O2-carrying capacity of the blood?

The Kidneys

When the kidneys detect reduced O2-carrying capacity of the blood they secrete the hormone -------.

Erythropoietin

The hormone ------ stimulates erythropoiesis by the ------.

Erythropoietin, bone marrow

The release of erythropoietin causes the ------ of ---carrying capacity of the blood.

increase, O2

The increase in O2-carrying capacity of the blood ----- the initial stimulus that triggered ------ secretion.

relieves, erythropoietin

Which mineral is essential for Hb synthesis?

Iron

---% of iron is stored in Hb, the remainder in the ----, -----, and less extent bone marrow.

65, liver, spleen

Free iron ions are -----, and its absorption into the bloodstream is controlled by ------ cells.

toxic, intestinal

Iron is stored inside cells as complexes bound to ------; complexes such as ---- and -----. In blood, iron is transported bound to a -------, called ------.

proteins, ferritin, hemosiderin tranport protein, tranferrin

Small amounts of iron are lost in ------, ------, and ------.

feces, urine, sweat

True or False: The average daily loss of iron is more in men that women.

False Note: menstrual flow increases the loss in women, women lose 1.7 mg while men lose 0.9 mg

Vitamin ---- and ----- are necessary for DNA synthesis and developing RBCs.

B12, folic acid (B9)

True or False: Sources of iron include: chicken liver, red meat, spinach.

True

Erythropoietin release: ---% from kidneys ---% from the ------

90% 10%, liver

New erythrocytes function for about ---- days.

120

Aged and damaged RBCs are engulfed by ----- of the ----, ------, and -----, and the hemoglobin is broken down

macrophages, liver, spleen, bone marrow

Hemoglobin breakdown into: ------ and ------.

Heme, Globin

Heme becomes ------, which is a waste product carried by ------.

Bilirubin, the plasma

Globin is broken down into ---------- and returned to bloodstream.

amino acids

The heme group breakdown into ----- stored as ferritin and -------. It then goes to the ------.

iron, hemosiderin liver

From the liver, iron is bound to ----- as it is released into the bloodstream as needed for erythropoiesis.

transferrin

Bilirubin is picked up by the blood from the ----- then secreted into the ------- in bile.

liver, small intestines note: it is metabolized into the substance that gives feces its brown color

True or False: Food nutrients such as Vitamin B12 and folic acid are absorbed from the intestines and enter the lymph.

False, blood*

Any condition that lower the O2 transported to tissues will increase/decrease erythrocyte production. Give two examples of such conditions.

increase anemia, high altitude

Destruction of a major portion of the bone marrow via X-ray therapy will lead to ----- of the remaining bone marrow. It will also cause an increase is ---- production.

hyperplasia erythrocyte

In high altitude: Air breathed has lower PO2, so there will be a decrease/increase of inspired PO2

decrease

In high altitude: Air breathed has lower PO2, so there will be a decrease of inspired PO2. This will lead to a decrease/increase in PAO2 that will lead to a decrease/increase in PaO2

decrease, decrease

In high altitude: Air breathed has lower PO2, so there will be a decrease of inspired PO2. This will lead to a decrease in PAO2 that will lead to a decrease in PaO2 The decrease in PaO2 will result in ------- that will cause -------.

Hypoxemia (low O2 in blood), Hypoxia (low O2 in tissues)

In high altitude, what controls the RBC production is ------ instead of the erythrocyte concentration in the blood.

the amount of O2 transported in relation to O2 demand

Various diseases of the circulation lower blood flow through peripheral vessels. Give two examples.

Prolonged cardiac failure, lung diseases like asthma or lung edema

Disease of the circulation: Decrease blood flow -> tissue ----- -> increased erythrocyte production -> decrease/increase hematocrit and blood volume

hypoxia, increased

True or False: The hormone erythropoietin is cannot be produced in a laboratory.

False, can*

Genetically engineered EPO is used to increase/decrease RBC production in patients with suppressed erythropoietic activity.

increase

Give one example of a patient with suppressed erythropoietic activity.

Cancer patient undergoing chemotherapy Note: the drugs interfere with the rapid cell division of BOTH cancer cells and developing RBCs)

Renal dialysis patients with kidney failure produce ----- EPO to support normal erythropoiesis.

too little

True or False: The ready availability of this hormone has significantly increased the need for blood transfusions, as it prevents erythropoiesis.

False, decreased*, enhances* erythropoiesis

The male sex hormone, testosterone: Increases/decreases EPO production from the kidneys -> explains partially the increased/decreased RBC counts and Hb levels in males.

Increases, increased

Physiology of Erythrocytes 1 Flashcards

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