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Phase 1: weeks 1-5 > Blood > Flashcards

Blood Flashcards

1
Q

What are the components of blood and which is the most abundant?

A

Plasma (55%)
RBCs (carry gases)
WBCs (immune function)
Platelets (aka thrombocytes - involved in clotting)

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2
Q

Describe characteristics of RBCs (size, production, last, features)

A

Have no nucleus and are biconcave in shape to maximise surface area for oxygen uptake.
No mitochondria so don’t take up oxygen
Lasts for 120 days
Made in bone marrow
Small and flexible to fit into blood vessels
Strong and flexible plasma membrane to squeeze through capillaries

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3
Q

What is plasma made up of?

A 
Water (90%)
Electrolytes
Gases
Nutrients
Plasma proteins
Waste products
Regulatory substances
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4
Q

Describe some plasma proteins

A 
Albumin: main carrier molecule, maintains osmotic pressure, transport insoluble molecules 
Globulin: participate in immune function (immunoglobulins)
Fibrinogen: soluble, involved in blood clotting
Regulatory proteins (enzymes, hormones, vitamins)
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5
Q

Describe characteristics of platelets (including shape, origin, duration)

A

Small, disc shaped fragments made from megakaryocytes. Negatively charged surfaces, survive for 6 days.

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6
Q

List the functions of blood

A

Regulates body temperature
Carries nutrients and oxygen to body tissues
Carries waste products to kidney
Forms clots to control bleeding and blood loss
Contains antibodies and WBCs to combat infection

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7
Q

Why are blood clots important?

A

They limit excessive blood loss and prevent infection entering the body.

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8
Q

Define Haemostasis

A

Stopping of bleeding

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9
Q

Describe primary haemostasis

A

Vasospasm occurs as the smooth muscle surrounding the blood vessel contracts. This causes vasoconstriction to limit blood flow to the area.

Von Willebrand factors help platelets to bind easily to the exposed collagen.
Platelets release chemicals from their granules. ADP so release which stimulates platelet aggregation. Thromboxane A2 stimulates platelets aggregation and vasoconstriction. Serotonin also increases vasoconstriction.
Platelets change their shape and develop pseudopodia which makes platelets stick to each other more easily.
Platelets aggregate and clump together to seal the area, forming a temporary platelet plug. A platelet plug stops bleeding but needs to be strengthened further with clotting factors.

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10
Q

What prevents platelets from aggregating to healthy cells?

A

Prostacyclin and Nitric Oxide

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11
Q

What differentiates the extrinsic and intrinsic clotting cascade?

A

Intrinsic:
activated by internal damage
Exposure of collagen fibres
Slow (4-6 minutes)

Extrinsic:
Activated by external damage
Release of tissue factor (factor 3) from external damage
Fast (25-50 seconds)

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12
Q

Describe the intrinsic coagulation cascade

A

Factor 12 becomes activated, 12a activates 11, 11a activates 9, 9a (along with calcium and factor 8) activates factor 10

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13
Q

Describe the extrinsic coagulation cascade

A

Factor 3 (tissue factor) activates factor 7, factor 7a activates factor 10.

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14
Q

Describe the common pathway for coagulation

A

Factor 10, along with calcium and factor 5, activate Thrombin from Prothrombin (factor 2). Thrombin activates fibrin from fibrinogen (factor 1).
Fibrins strengthens the platelet plug by forming a mesh.

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15
Q

How is a clot dissolved?

A

Tissue plasminogen activator converts plasminogen to plasmin which breaks down the fibrin in the clot

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16
Q

What is the role of factor 13?

A

Factor 13 is a fibrin stabilising factor which forms covalent bonds with soluble fibrin strands and converts them into an insoluble strong fibrin mesh.

17
Q

Where is erythropoietin produced and what is its role?

A

Peritubular cells in kidneys

It is a hormone which promotes formation of RBCs in bone marrow.

18
Q

What is haematopoiesis and where does it occur?

A

It is the production of new blood cells and occurs int he bone marrow

19
Q

What property do haematopoietic cells have that allow them to produce many blood cells?

A

Multipotent

20
Q

Draw the haematopoietic lineage

A

Primary myeloid progenitor cell, primary lymphoid progenitor cell
ETC

21
Q

Describe the first aid response to a cut which may potentially contain foreign objects (glass).

A

Ensure airway is clear
Take precautions (gloves)
Cut or remove clothing over the wound if needed.

If there is a foreign object do not remove it as it may be preventing severe blood loss.

Apply pressure around the wound

If no foreign object: Apply direct pressure to the area of wound with your palm or fingers.

Raise and support injured area: maintaining the pressure, elevate the wound above the level of the heart so that the blood has to work against gravity.

Bandage dressing in place: check circulation beyond bandage every 10 minutes. Loosen and reapply the bandage if needed.

Call for emergency help: call 99 and give information about site of injury and extent of bleeding. Monitor vital signs e.g. pulse, breathing, response.

22
Q

What is triage, when is it used?

A

Triage is used to categorise patients according to urgency.
It is a dynamic process that should be repeated at regular intervals.
The most commonly used triage system in the UK is the Manchester one.
It is used to manage patient flow when clinical need exceeds capacity

23
Q

What clotting cascade are Activated Partial Thromboplastin Time and Prothrombin Time used to assess?

A

APTT: assesses intrinsic pathway
PT: assesses extrinsic pathway

24
Q

What clotting factors does APTT evaluate?

A

12, 11, 10, 9, 8, 5, prothrombin and fibrinogen

25
Q

What clotting factors does PT evaluate?

A

7, 10, 5, prothrombin, fibrinogen

26
Q

What is the normal time for activated partial thromboplastin time?

A

25-39 seconds

27
Q

What is the normal Partial thrombin time?

A

12 seconds

28
Q

What effect do citrate ions have on blood clotting?

A

They chelate calcium ions (bind to them o make them inactive) so blood cannot coagulate

29
Q

In a lab, what can be used to mimic blood platelets?

A

Suspension of negatively charged phospholipids on particles of kaolin.

30
Q

What is heparin sulphate and what does it bind to?

A

A natural anticoagulant which binds to antithrombin III and enhances inhibition

31
Q

What charge does heparin carry?

A

Negative

32
Q

Wha protein is missing from serum compared to plasma?

A

Fibrinogen

33
Q

If someone has a prolonged Prothrombin Time, what

may it be caused by?

A

Vitamin K deficiency or liver disease

34
Q

What effect does warfarin have on PT?

A

Prolongs/slows it because it is a vitamin K antagonist

35
Q

What effect does heparin have on APTT?

A

Prolongs/slows it

Phase 1: weeks 1-5 (23 decks)

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