Intro to Blood Flashcards

1
Q

What are the functions of blood ?

A
  • transport
  • regulation of pH, osmosis, body temp
  • maintenance of homeostasis
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2
Q

Define Hematocrit

A

the ratio of the volume of red blood cells to the total volume of bold
(packed cell volume)

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3
Q

What are the main components of blood ?

A
  • Plasma - 55%
  • Erythrocytes - 45% (formed elements)
  • Buffy coat = <1% ( formed elements)
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4
Q

What are the 3 major categories of plasma proteins ?

A
  • albumins - smallest and most abundant
  • globulins
  • fibrinogen
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5
Q

Describe albumins

A
  • most abundant - 3.5 - 5.0 g/dL blood
  • contributes to viscosity & osmolarity
  • influences blood pressure, flow and fluid balance
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6
Q

Describe Globulins

A
  • antibodies
  • 1.0 -1.5 g/dL blood
  • provide immune system function
  • alpha, beta and gamme globulins
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7
Q

Describe Fibrinogen

A
  • 0.2-0.45 g/dL blood
  • precursors of fibrin threads that help form blood clots
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8
Q

What are some functions of plasma proteins ?

A
  • blood viscosity
  • provide 1/6th of the total buffering power of the blood
  • transport substances circulating in the blood
  • essential for blood clotting mechanisms
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9
Q
A
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10
Q

What are some of the sub types of granulocytes ?

A
  • neutrophils
  • eosinophils
  • basophils
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11
Q

What are the sub-types of granulocytes ?

A
  • lymphocytes
  • monocytes
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12
Q

What’s another word for platelets ?

A

thrombocytes

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13
Q

What is haematopoiesis stimulated by?

A

erythropoietin, thrombopoietin & colony-stimulating factors

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14
Q

How are erythrocytes formed ?

A
  • haemotopoietic stem cells
  • committed stem cells
  • early erythroblast
  • late erythroblast
  • normoblast
  • reticulocyte
  • erythrocyte
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15
Q

Describe the structure of haemoglobin

A
  • each Hb molecule consists of 4 protein chains (globins) and 4 heme groups
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16
Q

Describe heme groups

A

non-protein moeity that binds oxygen to ferrous ion (Fe2+) at its centre

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17
Q

Describe Globins

A
  • 2 alpha & 2 beta chains
  • 5% carbon dioxide in blood is bound to global moiety
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18
Q

What is the haemoglobin concentration of whole blood?

A

females = 12-16 g/dL
males = 13-18 g/dL

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19
Q

What is the red blood cell count in men and women?

A

men = 4.6-6.2 million/uL
women = 4.2-5.4 million/uL

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20
Q

Why are RBC counts lower in women ?

A
  • androgens stimulate RBC production
  • women have periodic menstrual loss
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21
Q

Define Erythropoiesis

A

production of red blood cells

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22
Q

Describe the negative feedback control involved in erythrocyte homeostasis

A
  • drop in RBC count causes kidney hypoxemia
  • kidney production of erythropoietin stimulates bone marrow
  • RBC count increases in 3/4 days
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23
Q

What are some examples of stimuli which increases erythropoiesis ?

A
  • low levels of oxygen (hypoxemia)
  • high altitude
  • increase in exercise
24
Q

How long do blood cells circulate for ?

25
Where are expired erythrocytes broken down ?
- in the liver and spleen - the freed haemoglobin is degraded into heme and globin - cell fragments are phagocytised
26
What are some examples of erythrocyte disorders ?
- polycythemia = an excess of RBCs - anaemia = deficiency of RBCs or Hb
27
What are the effects on anaemia?
- tissue hypoxia and necrosis - low blood osmolarity - low blood viscosity
28
Define antigen
substances that can induce an immune response
29
Define antibody
proteins that recognise and bind to antigens
30
What is the origin of antigens ?
within the body or externally
31
What is the origin of antibodies ?
within the body
32
What are neutrophils, eosinophils, basophils ?
Granulocytes
33
Describe Neutrophils
- polymorphonuclear leukocytes - 60-70% of WBCs - barely visible granules in cytoplasm - 3-5 lobed nucleus - phagocytosis of bacteria & release antimicrobial chemicals
34
Describe Eosinophils
- 2-4% of WBCs - large rosy-orange granules - bi-lobed nucleus - phagocytosis of antigen-antibody complexes, allergens and release enzymes to destroy parasites
35
Describe Basophils
- <1% WBCs - large, abundant, violet granules - large S-shaped nucleus - secrete histamine & heparin
36
Define granules
contain enzymes and other chemicals employed in defence against pathogens
37
Describe Lymphocytes
- 25-33% - variable amounts of bluish cytoplasm - ovoid/round - uniform dark violet nucleus
38
Describe monocytes
- 3-8% - largest WBC - Ovoid, kidney/horseshoe shaped nucleus
39
What are the properties of white blood cells ?
phagocytosis, diapedesis, ameboid motion, chemotaxis
40
What are the 4 key features of acute inflammation ?
1. redness 2. heat 3. swelling 4. pain
41
Describe platelets
- colourless - 2-4 um diameter - no nucleus - life span = 8-12 days
42
What are the functions of platelets ?
- secrete vasoconstricors to help reduce blood loss - initiate formation of clot-dissolving enzyme - chemically attract neutrophils & monocytes to sites of inflammation - phagocytise and destroy bacteria
43
What are some mechanisms to prevent blood loss ?
- formation of platelet plug - formation of blood clot - clot retraction - growth of fibrous tissue
44
How are Platelet Plugs formed ?
- damaged blood vessels - chemicals released from platelets - inhibitors
45
Define coagulation
- last & most effective defence against bleeding - conversion of plasma protein fibrinogen into insoluble fibrin threads to from a framework clot
46
What are substances that promote coagulation called ?
procoagulants
47
What are substances that inhibit coagulation called ?
anticoagulants
48
Where procoagulants produced ?
in the liver
49
Describe the process of coagulation
- procoagulants activate 1 factor and it will activate the next to form a reaction cascade
50
What are the 2 coagulation pathways ?
extrinsic & intrinsic
51
Describe the extrinsic pathway
- initiated by release of tissue thromboplastin (factor III) from damaged tissue - cascade to factor VII, V & X (fewer steps) - calcium required
52
Describe the intrinsic pathway
- initiated by platelets releasing Hageman factor (factors XII) - Cascade to factor XI -> IX -> VIII -> X - calcium required
53
What processes prevent inappropriate clotting?
- platelet repulsion - thrombin dilution - natural anticoagulants - blood clot dissolution
54
Describe platelet repulsion
- platelets don't adhere to prostacyclin-coating
55
Describe natural anticoagulants
- heparine (from basophils & mast cells) interferes with formation of prothrombin activators - antithrombin (from liver) deactivates thrombin before it can act on fibrinogen
56
Describe Blood Clot Dissolution
- fibrinolysis = dissolution of a clot - factor XII speeds up the formation of kallikrein enzyme - kallikrein converts plasminogen into plasmin, a fibrin-dissolving enzyme that breaks up the clot