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Section 4C CVD Conditions > Red Blood Cell Pathologies > Flashcards

Red Blood Cell Pathologies Flashcards

1
Q

What are the 3 plasma proteins in the blood?

A
  1. Albumin
    - transport
    - maintenance of osmotic pressure
  2. Immunoglobulins
    - immunity
  3. Clotting factors
    - haemostasis
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2
Q

Describe haemoglobin

A

Structure:

  • 4 globin chains bound to 4 haem groups
  • each haem group can bind O2 molecule
  • each haemoglobin molecule can bind to up to 4 O2 molecules (100% saturated)

Transport:

  • 250 million molecules of Hb per RBC
  • make up 90% of dry weight of RBC
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3
Q

Describe the makeup of blood:

A

5.5L average adult BV

45% RBCs
55% Plasma
<1% WBCs and platelets

RBCs:
- carry haemoglobin for transport of O2 and CO2

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4
Q

Describe haemopoiesis:

A

The production of cellular components of blood in the blood marrow

  • most occurs in red bone marrow (flat bones including pelvis, sternum, skull, ribs, vertebrae, scapula and long bones)
  • some WBCs made in yellow bone marrow

Haemopoietic stem cells:

  • provide precursor cells for all blood cells
  • capable of self renewal
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5
Q

Describe erythropoiesis:

A

Production of RBCs

  1. EPO (erythropoietin) hormone is released from kidneys and liver in response to hypoxia
  2. EPO stimulates RBC production from haemopoietic stem cell in bone marrow
  3. nutrients required for erythropoiesis = IF, B12, B9 (folate), iron, copper
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6
Q

What is erythrocytosis?

A

Abnormally high number of RBCs

- usually a response to chronic hypoxia (triggering EPO release and RBC production)

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7
Q

What is anaemia?

A

Abnormally low number of RBCs

Can be caused by:

  • decreased production of RBCs
  • increased loss of RBCs

Diagnosis:
< 130 g/L Hb (male)
< 120 g/L Hb (female)

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8
Q

What are the 3 major types of anaemia?

A

Iron deficiency anaemia (IDA)

Megaloblastic / Macrocytic Anaemia

Haemolytic Anaemia

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9
Q

Describe the aetiology or iron deficiency anaemia

A
  1. excessive blood loss (menorrhagia, haemorrhoids, GIT bleeding)
  2. iron malabsorption
    (coliac, diarrhea, parasitic infection)
  3. inadequate dietary intake
  4. increased iron demand (pregnancy)
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10
Q

What is iron and its role?

A
  • essential component of haemoglobin (and therefore vital for O2 transport)

80% located in Hb
20% in storage (ferritin, haemosiderin)
<1% in plasma (transferrin, serum ferritin)

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11
Q

What are the 4 SSX specific to iron deficiency anaemia?

A
  1. koilonychia (thin, brittle, ridged nails)
  2. glossitis (shiny red tongue)
  3. angular stomatitis (dry sore corners of mouth)
  4. alopecia
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12
Q

What are the general SSX of anaemia?

A
  • fatigue
  • dyspnoea
  • palpitations
  • dizziness
  • loss of appetite
  • headache
  • dim vision
  • paraesthesia in digits
  • pallor
  • tachycardia
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13
Q

What are the 2 major types of IDA?

A
  1. microcytic - RBCs too small

2. hypochromic - pale RBCs

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14
Q

What is the most common form of anaemia?

A

Iron deficiency anaemia (IDA)

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15
Q

Which anaemia is connected to B12 / B9 (folate) deficiency?

A

Megaloblastic / Macrocytic Anaemia

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16
Q

What are the sources of B12 / B9 (folate)?

A

B12:

  • animal products
  • absorption requires intrinsic factor IF-B12

B9 (folate):
- green vegetables, meat, eggs, fish

17
Q

What is the pathology of megaloblastic / macrocytic anaemia?

A
  1. deficiency in B12 or B9 (folate) interferes with DNA synthesis and mitosis
  2. causes release of large, immature RBCs into blood, called:
    - megaloblastic (in marrow)
    - macrocytic (in blood)
  3. Macrocytic RBCs cannot carry normal amount of haemoglobin
18
Q

What are the risk factors for megaloblastic / macrocytic anaemia?

A
  1. inadequate intake of B12 / B9 (folate) - vegetarian diet
  2. pernicious anaemia (production of antibodies decreases absorption in GIT or attacks IF)
  3. Stomach disorders (decreased production of IF)
  4. Terminal ileum disorders (Crohn’s, coeliac) - malabsorption of IF B12 complex
19
Q

What is the IF-B12 complex?

A

IF = intrinsic factor, produced in stomach

  • necessary for absorption of B12 (binds to B12 to form IF-B12 complex and allow absorption to occur)
20
Q

What is haemolytic anaemia and its connection to thalassaemia?

A

Haemolytic anaemia = any anaemia characterized by short lifespan RBCs, meaning that marrow can’t keep up with demand for RBCs

Thalassaemia = inherited haemolytic anaemia
- autosomal recessive disorder

Beta Thalassaemia

  • most common form of thalassaemia
  • inadequate formation of beta chains affects Hb molecule
21
Q

What are the SSX of Beta Thalassaemia?

A
  • severe anaemia within months of birth
  • bone marrow hypoplasia causes bony changes

Complications:

  • hepatomegaly (excess iron storage due to blood transfusions)
  • cardiac failure
22
Q

What is the treatment for beta thalassaemia?

A
  • blood transfusions
  • iron chelation (to manage iron overload caused by multiple transfusions)
  • bone marrow transplant

Fatal if transplant does not occur

23
Q

What is haemochromatosis?

A

Definition:
- iron overload

Aetiology:

  • primary: inherited autosomal condition
  • secondary: caused by treatment of thalassaemia major (transfusions)

Classic triad SSX:

  • cirrhosis
  • skin pigmentation
  • diabetes melittus

Section 4C CVD Conditions (5 decks)

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