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BIOL 273 - Principles of Human Physiology 1 > 4.5 - Blood, Haematopoiesis, & Haemostasis > Flashcards

4.5 - Blood, Haematopoiesis, & Haemostasis Flashcards

1
Q

What is blood?

A

The circulating component of extracellular fluid responsible for carrying substances around the body

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2
Q

List the 4 components of blood:

A
  1. Plasma
  2. Red Blood Cells (RBCs)
  3. White Blood Cells
  4. Platelets
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3
Q

What is plasma?

A

The fluid aspect of blood

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4
Q

What does “erythro” mean literally?

A

Red

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5
Q

List the characteristics of RBCs

A
  • also known as erythrocytes
  • shape: bi-concave
  • contain haemoglobin protein
  • major function: gas transport (O2 and CO2)
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6
Q

TRUE OR FALSE:

Rectify statement if false

White blood cells are the most abundant cells in blood

A

FALSE:

RBCs are the most abundant cells in blood

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7
Q

TRUE OR FALSE:

Rectify statement if false

In humans (mammals), RBCs lack a nucleus only.

A

FALSE:

lack BOTH nucleus and mitochondria

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8
Q

White blood cells (leukocytes) function in immune responses. List the different types:

A
  • Lymphocytes
  • Monocytes (mature macrophage)
  • Granulocytes: Neutrophils, eosinophils, basophils (mast cells)
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9
Q

What are the professional phagocytes in the body? What do they do?

A
  • macrophage and neutrophils

- they engulf and destroy foreign entity in tissues

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10
Q

Why is the synthesis of haemoglobin crucial?

A
  • for RBCs to transport O2
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11
Q

What is haemoglobin? List some characteristics:

A
  • large complex molecule made up of 4 protein chains (globins), 2 Alphas and 2 Betas
  • each globin subunit is wrapped around an iron containing haeme group
  • haeme group C-H-N porphyrin ring contains an Fe in the center
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12
Q

Define platelets and their functions:

A
  • also known as thrombocytes
  • involved in blood clotting
  • derived from megakaryocytes: pinch off and have no nucleus
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13
Q

Low dietary iron can result in ____

A

anemia

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14
Q

Explain the haemoglobin/oxygen saturation

A
  • curve is s-shaped with a steep portion followed by plateau
  • O2 highest partial pressure @ alveoli where RBCs are packed
  • RBCs travel to arteries and reach capillaries where they give off the O2 and partial pressure decreases
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15
Q

What are factors affecting haemoglobin-O2 binding? What type of modification is that?

A
  • allosteric modification
  • temperature and pH
  • increases in temperature decreases haemoglobin-oxygen affinity
  • increases in blood CO2 and H+ decreases haemoglobin-oxygen affinity
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16
Q

What is the Bohr effect?

A
  • shift in haemoglobin saturation due to pH
17
Q

How does O2 unloading happen at the tissues?

A
  • the more active the tissue, the greater the increase in temperature, PCO2, and H+
  • relative to the lungs, these factors are elevated in tissues
  • leads to more O2 released
18
Q

What do “haima” and “poeisis” mean?

A

haima = blood

poeisis = formation

19
Q

Where are blood cells produced?

A

RED Bone marrow

20
Q

What is the precursor from which all blood cells arise?

A

pluripotent haematopoietic stem cell

21
Q

What are uncommitted stem cells?

A

lymphocyte stem cells

22
Q

Progenitor stem cells are committed to one or two cell types; list them.

A
  • eosinophil
  • mast cell
  • basophil
  • neutrophil
  • dendritic cell
  • monocyte (macrophage)
  • megakaryocytes ( platelets)
  • Reticulocyte (Erythrocyte)
23
Q

What are cytokines?

A
  • small peptides/proteins secreted by one cell to send signals to another
  • cytokines guide the paths taken by committed progenitor cells
  • e.g. growth factor, modifying factor
24
Q

What is leukopoeisis and what regulates it?

A
  • formation of white blood cells

- regulated by colony stimulating factors (CSFs)

25
Q

Where do CSFs come from and what do they do?

A
  • released by endothelial cells, marrow fibroblasts, and white blood cells
  • induce cell division and cell maturation in stem cells
26
Q

Cytokines released by leukocytes regulate further leukocyte production. What would happen if you had an active bacterial infection?

A
  • goal is to fight infection: immune system

- cytokines will push for production of macrophage and neutrophils (professional phagocytes of the body)

27
Q

What is thrombopoeisis?

A

Formation of thrombocytes (platelets)

28
Q

What are the parent cells of thrombocytes?

A

Megakaryocytes

29
Q

Growth and maturation of thrombocytes is regulated by ____

A

cytokine thrombopoeitin (TPO)

30
Q

Where does the megakaryocte reside?

A
  • in the bone marrow
  • extends its outer edges through the endothelium (cells lining the blood vessels) into the blood stream
  • ends fragment into disk-like platelets, no nucleus, have mitochondria, smooth ER, granules filled with clotting proteins and cytokines
31
Q

Are platelets always present in the blood? Explain

A

Yes, but not activated until there is damage to the walls of the circulatory system

32
Q

What is erythropoeisis? What regulates it?

A
  • formation of red blood cells

- cytokine erythropoeitin (EPO)

33
Q

What is erythropoeitin? Where is it made? What is EPO used for?

A
  • cytokine that regulates erythropoeisis
  • glycoprotein made primarily in kidneys
  • genetically engineered to stimulate RBC production in patients
34
Q

What is haemostasis?

A

haeme = blood, stasis = stoppage

  • prevents blood from being loss from damaged vessels
  • must be fixed under pressure
35
Q

What are the steps of haemostasis?

A
  1. Vascular spasm:
    - similar to putting pressure on a bleeding wound
    - damaged endothelium of blood vessel releases vasoconstrictive paracrines
    - leads to decreased blood flow due to increasing resistance
    - promotes formation of platelet plug
  2. Platelet plug temporarily block break:
    - collagen is normally in the sub endothelial layer
    - platelets stick together and become activated
    - releases cytokines, which activates more platelets
    - activated platelets stick together (aggregation) to form loose platelet plug
    - slows down blood flow in the vessel and provides a framework for clotting
  3. Blood clot to seal the break: result of coagulation cascade
    - inactive plasma proteins are activated by exposure to either factor XII to collagen (intrinsic pathway) or exposure to tissue factor III ( extrinsic pathway) released from damaged cells
    - both pathways merge into the common pathway and lead to activation of thrombin, which cleaves fibrinogen into fibrin
    - thrombin activates factor XIII which cross-links fibrin into long fibres that intertwine to form a fibrin network
    - intertwined fibres reinforce the platelet plug making it a clot
    - excessive clotting produces a thrombus: clot to block blood vessels
36
Q

explain healing

A
  • during clot formation, plasminogen is converted into plasmin by thrombin or tissue plasminogen activator (tPA)
  • plasmin enzyme dissolves the clot -> fibrinolysis
  • as repair progresses, the clot slowly shrinks

BIOL 273 - Principles of Human Physiology 1 (24 decks)

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