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Anatomy & Physiology > Hematology- erythrocytes > Flashcards

Hematology- erythrocytes Flashcards

1
Q

blood composition

A

-55% plasma
-45% formed elements: WBCs (leukocytes), RBCs (erythrocytes), platelets (thrombocytes)

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2
Q

hematocrit

A

% of blood volume that is RBCs
47 % - or + 5% for males
42% - or + 5% for females

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3
Q

characteristics of blood

A
  • pH: 7.4
  • temp: 38 C (100.4 F)
  • % of body weight: 8%
  • volume: 5-6 L males, 4-5 L females
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4
Q

functions of blood

A
  1. distribution
  2. regulation
  3. protection
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5
Q

functions of blood: distribution

A

distribution of…
- O2 and nutrients to body cells
- metabolic wastes to the lungs and kidneys for disposal
- hormones from endocrine organs to target organs

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6
Q

functions of blood: regulation

A

regulation of…
- body temperature by absorbing and distributing heat
- maintain normal pH using buffers
- adequate fluid volume in the circulatory system

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7
Q

functions of blood: protection

A

protection against…
- blood loss (proteins and platelets initiate clot formation)
- infection: antibodies and WBCs defend

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8
Q

blood plasma composition

A

90% water
8% proteins
1%: nitrogenous by-products of metabolism (lactic acid, urea, creatinine. nutrients (main four macromolecules from food) O2 and CO2, electrolytes, hormones)

plasma is a suspension for WBCs and RBCs

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9
Q

what’s special about WBCs?

A

they are the only type of complete cells

RBCs have no nucleii or organelles, and platelets are fragments of cells

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10
Q

formed elements

A

most formed elements survive int eh bloodstream for only a few days

most blood cells come from stem cells in marrow and don’t divide.

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11
Q

erythrocytes

A
  • biconcave disks (allows flexibility and good SA:V), anucleate, no organelles
  • filled with hemoglobin (Hb) for gas transport
  • major factor contributing to blood viscocity
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12
Q

erythrocyte function

A
  • dedicated to gas transport
    this is because hemoglobin binds reversibly to O2, so the O2 can be released and exchanged
  • hemoglobin structure: protein globin and heme pigment bonded to each other
  • iron atom in each heme can bind to one O2 molecule
  • each Hb molecule can transport four O2 molecules
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13
Q

Hemoglobin (Hb)

A
  • O2 loading in the lungs produces oxyhemoglobin (bright ruby red)
  • unloading in the tissues because of reversible reaction produces deoxyhemoglobin (deep red)
    -CO2 loading in tissues produces carbaminohemoglobin which carries 20% of CO2 in blood
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14
Q

how does blood “know when to release O2?

A
  • binding of O2 to Hb is affected by CO2 concentration (high CO2 concentration, low pH concentration)
  • the chemical rxn when tissues put out CO2 changes the shape of the Hb protein which then kicks off oxygen.
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15
Q

hematopoiesis/hemopoiesis/ERYTHROPOIETIN (EPO)

A

blood cell formation
- occurs in red bone marrow
- hemocytoblasts (blood stem cells) give rise to all formed elements

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16
Q

erythropoiesis

A

RED blood cell production

  1. stem cell (hemocytoblast) comes in contact with EPO (chemical hormone)
    • when EPO is present, the stem cell differentiates into…
  2. proerythroblas
  3. turns into erythrobast
    • makes ribosomes and accumulates Hb
  4. turns into nomoblast
    • kicks out nucleus and becomes…
  5. reticulocyte differentiates into…
  6. erythrocyte
17
Q

regulation of erythropoiesis

A
  • too few RBCs lead to tissue hypoxia
  • too many RBCs increases blood viscosity
  • balance between RBC prodution and destruction depends on: hormonal controls and good supplies of iron, amino acids (used to make globin part of Hb)
18
Q

hormonal control of erythropoiesis

A

EPO (erythropoietin)
- direct stimulus for erythropoiesis
- released by kidneys in response to hypoxia

19
Q

causes of hypoxia

A
  • hemorrhage or increased RBC destruction that reduces RBC #s
  • insufficient Hb (iron deficiency)
  • reduced availability of O2 (high altitude, vigorous exercise, lack of breathing)
20
Q

effects of EPO

A
  • more rapid maturation of bone marrow cells
  • increased circulating reticulocyte count in 1-2 days
  • testosterone enhances EPO prodction
21
Q

if stimulus interrupts blood homeostasis…

A
  1. kidney releases EPO
  2. EPO stimulates red bone marrow
  3. enhanced erythropoiesis increases # of RBCs
  4. O2 carrying ability of blood increases
22
Q

erythrocyte life cycle

A
  • life span: 100-120 days
  • old RBCs become fragile and Hb begins to degenerate
  • macrophages engulf dying RBCs in the spleen
  • when the RBCs die, they get broken down into heme and globin
    • iron is saved for re-use
    • heme is degraded to yellow pigment, bilirubin
    • liver secretes bilirubin (in bile) into intestines
    • shit out bilirubin
    • globin is metabolized into amino acids
23
Q

erythrocyte disorders anemia

A

anemia: blood can’t carry enough O2
- category of diseases
- blood O2 levels can’t support normal metabolism
- accompanied by fatigue, paleness, shortness of breath, and chills

24
Q

causes of anemia

A
  1. low # of RBCs
  2. low hemoglobin count
  3. pernicious anemia
  4. abnormal hemoblogin
25
Q

causes of anemia: insufficient RBCs

A
  • hemorrhagic (bleeding) anemia: acute or chronic loss of blood
  • hemolytic anemia: RBCs rupture
  • aplastic anemia: destruction or inhibition of red bone marrow, not making enough RBCs as should be
26
Q

causes of anemia: low hemoglobin count

A
  • iron deficiency anemia: secondary result of hemorrhagic anemia or not eating enough iron or impaired iron absorption in digestion
27
Q

pernicious anemia

A
  • not enough B12
  • lack of intrinsic factor needed for absorption (in intestines)
  • treated by injection of B12
28
Q

abnormal hemoglobin

A
  • thalassemia: globin made wrong, so RBCs are shaped differently (fragile, thinly shaped)
  • sickle cell anemia: 1 DNA base pair is changed for abnormal hemoglobin. causes RBCs to become sickle shaped (half moon) in low oxygen situations
  • polycythemia: excess of RBCs that increases blood viscosity. results from bone marrow cancer, less available O2, blood doping.

Anatomy & Physiology (20 decks)

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