Physiology Flashcards

1
Q

How many oxygen molecules can one RBC carry? How does it do so?

A

4 oxygen molecules
2 alpha and 2 beta chains binding to each heme group

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2
Q

What is hematocrit?

A

Relative volume of RBC out of total blood count

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3
Q

How is reticulocyte count useful?

A

Helps determine if erythropoietin is normal

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4
Q

Where is erythropoiesis done in a fetus?

A

Yolk sac but upon maturation, in liver, spleen and lymph nodes

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5
Q

Where is erythropoiesis done in a child less than 5 years old?

A

Bone marrow

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6
Q

Where is erythropoiesis done in a teenager?

A

Bone marrow
Sternum
Vertebrae
Proximal end of long bone

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7
Q

Where is erythropoiesis done in an adult?

A

Bone marrow
Sternum
Vertebrae

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8
Q

How is regulation of erythropoiesis done?

A

By the kidneys.
Low oxygen delivery stimulate kidney release more erythropoietin

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9
Q

What happens during erythropoiesis?

A

Growth factors stimulate hematopoietic stem cells to give rise to proerythroblasts

Proerythroblasts develop into erythroblasts

Erythroblast loses its nucleus to form normoblasts and reticulocytes

Reticulocytes continue to synthesis and leave bone marrow for differentiation

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10
Q

How do RBC destruct?

A

Self rupture occurs where a lack of protein synthesis causes membrane to be fragile

Rupture into tiny vessels of spleen

Macrophage takes up dying component

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11
Q

How is iron from RBC recycled and stored?

A

Recycled in bone marrow

Stored in liver

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12
Q

How is globin from RBC recycled?

A

Metabolized to AA

Released into circulation

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13
Q

How is heme from RBC excreted?

A

Degraded to bilirubin

Excrete via liver and bile into urine and feces

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14
Q

Define anemia and name a few conditions associated with anemia

A

Reduction below normal capacity of blood to carry O2 due to decreased erythrocytes and hemoglobin

Examples include:
- Malaria
- Aplastic anemia
- Hemorrhagic anemia
- Sickle cell disease

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15
Q

Define polycythemia

A

An excess circulating erythrocytes causing elevated hematocrit

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16
Q

What are some conditions associated with polycythemia?

A

Tumour

Adaptive mechanism to high altitude places

Dehydration

17
Q

Define leukocytosis

A

WBC higher than normal, more than 1.1 x 10 cells/ mm3

18
Q

Why are people with leukemia more prone to getting cancer?

A

Immature WBC found along bloodstream of leukemia patients

When bone marrow becomes occupied with cancerous leukocytes, WBC being immature displaces remaining healthy ones and can cause issues such as immune deficiency

19
Q

What are the three phases of hemostasis?

A

Vasoconstriction
Platelet plug
Fibrin clot formation

20
Q

Why does vasoconstriction occur?

A

Decrease blood loss

Gives time for platelet and coagulation phase to occur

21
Q

What happens during vasoconstriction

A

Endothelial cell contracts to expose the basal lamina

22
Q

What is the purpose of platelet plug?

A

Closure of leak by formation of temporary patch

Release of chemical mediators to regulate blood clot

Contraction of blood clot

23
Q

What happens during the platelet plug phase?

A

Damage to endothelial walls expose collagen

Platelets activated and stick

Platelets then secrete more content

More platelets are activated and aggregate into a plug

Formation of platelet plug occurs

24
Q

Explain in details how the platelet adhesion step occurs

A

Von willebrand factor binds platelet to exposed collagen

Adhesion then activates platelet causing morphological changes and trigger release of platelet agonist

25
What are some platelet agonist?
ADP: Attracts and activates more platelets Tbx A2: Promotes aggregation and vasoconstriction
26
Draw the common coagulation cascade pathway
Refer to notes for answer
27
Draw the intrinsic coagulation pathway
Refer to notes for answer
28
Draw the extrinsic coagulation pathway
Refer to notes for answer
29
What is the function of thrombin?
Enhance own generation by acting as positive loop Activate factor XIII to stabilize fibrin mesh Platelet activation Release PF3 from platelets to activate intrinsic pathway
30
How does clot retraction occur?
Clot squeezes serum out of fibrin cloth and close leak
31
How does repair of clot occur?
PDGF stimulate vascular smooth muscle cell to build new vascular walls Endothelial cells stimulated by VEGF multiply and restore inner endothelial lining
32
Describe what happens during fibrinolysis
During clot formation, plasminogen is trapped in clot Surrounding tissue and vascular endothelial cells slowly release tPA which cleaves inactive plasminogen to protease plasmin Plasmin digest fibrin to dissolve clot Macrophage removes remaining of clot
33
What are the regulators of blood clot? Describe its mechanism of action
Prostacyclin: Inhibit platelet aggregation and spread of clot Serotonin: Inhibit ADP Blood clot: Limits spread of thrombin and other procoagulants
34
What does PTT measure?
Intrinsic and common coagulation cascade
35
What does PT measure?
Extrinsic and common coagulation cascade
36
What is INR?
Ratio of PT to general population's PT