CVS; Hemodynamics Flashcards
Circulating blood volume in 70kg man
5.6 L 8T% of the body weight
In bone marrow, percentage of cells that make up a) WBC producing cells b)RBC producing cells
WBC –> 75%
RBC –> 25%
The most abundant WBCs
neutrophils
Least abundant WBCs
Basophils
Half-life of platelets
4 days
Which cells form platelets?
Megakaryocytes in bone marrow, via creation of demarcation tunnels
Thrombocytosis refers to
increase in number of platelet count
half life of RBCs
120 days
Define hematocrit
the ratio of the amount of RBCs to the volume of blood (the percentage of RBCs in blood)
Amount of Hb in circulating blood in an adult
900g
Structure of hemoglobin A1c and its clinical significance.
Similar to Hemoglobin A2 which has 2 beta chains and 2 sigma chains, except Hemoglobin A1c’s beta chain is glycosylated.
Because it increases in patients with diabetes mellitus, it is a useful indicator of this condition and the effectiveness of treatment
Percent of hemoglobin in adults that is in the form A2?
2.5%
Structure of Hb
4 subunits; each subunit is made of a heme and a 2 chain polypeptide called globin
Factors affecting Hb’s affinity to oxygen?
Temperature
pH
concentration of 2,3-biphosphoglycerate
Change in charge of iron when Hb is converted to methemoglobin.
From ferrous (Fe2+) to ferric (Fe3+)
Congenital absence of methemoglobin reductase leads to
hereditary methemoglobinemia
Why fetal blood has high levels of oxygen?
Because it binds less strongly to 2,3-BPG, it’s able to hold oxygen for longer
2 molecules used to synthesize the heme portion of Hb?
glycine + succinyl-CoA
Explain the use of phototherapy in treating infants with jaundice.
Jaundice is caused by excess hemolysis resulting in build up of bilirubin. When exposed to light, bilirubin is converted to lumirubin which has a shorter half-life and so degrades more easily.
Functions of proteins.
- Maintain oncotic pressure
- Carriers of hormones, lipid soluble substances
- Involved in defense as antibodies
- 3rd mechanism of buffering capacity
- Involved in blood clotting coagulation cascade
- Albumin acts as source of nutrients because it’s rich in essential AAs
Between albumin and globulin which one is more abundant?
Albumin
Which globulin transports ferrous ions (Cu2+) ?
alpha-2 globulin
2 methods for measuring blood-flow
N20/Kety method (measures cerebral blood flow)
Plethysmography (water-tight chamber that uses the amount of water displaced to measure changes in arterial and venous volume)
Para-aminohippuric acid clearance rate (measures renal blood flow)
Dopplerflow meters (rely on ultrasonography; frequency of waves = rate of flow)
What is the critical velocity?
The velocity at or above which blood flow changes from laminar to turbulent
