Episode 3 - RBCs, Blood Functions and the Reticuloendothelial System (Bone Marrow, Spleen and Liver) Flashcards
Bone marrow is found mainly in:
Flat bones (sternum, ribs & cranial bones) Irregular bones (coxal bones, vertebrae and scapulae) Epihpyses of long bones (Femur and humerus)
In cases of sever blood loss, the body an convert ____ marrow back to ___ marrow to increase blood cell production.
yellow, red
In the adult, RBCs are synthesized in the ____. in the fetus, blood cells are also formed in the ____ and ____.
Adult - Red Bone Marrow
Fetus - Liver and Spleen (extramedullary erythropoiesis)
In adults, ____ may occur in diseases in which the bone marrow becomes destroyed or fibroses.
extramedullary erythropoiesis
In children, blood cells are actively produced in the marrow cavities of all the bones. By approx. age 20, the marrow in the long bones, except for the ____ and ____ has become inactive.
upper humerus and femur
The bone marrow contains multi potent uncommitted stem cells (pluripotent) that differentiate into one or another type of committed stem cells called ____ cells or ____ units.
progenitor cells
colony forming units
Erythropoiesis is under the control of many “growth factors” the most important one being ____ which is released by the kidneys (and to a smaller extent, the liver)
Erythropoietin (EPO)
RBCs enter the circulation as ____ which still contain some organelles. They remain for a few days in either the bone marrow or the spleen to mature to erythrocytes.
reticulocytes
Absolute ingredients for making normal RBCs are:
amino acids
iron
folic acid
vitamin B12
Erythropoietin production involves a ____ feedback loop.
negative
RBCs increase O2 delivery, this inhibits kidney release of EPO.
A RBC integral protein that functions in anion transport, resulting in one-for-one exchange of bicarbonate for chloride across the membrane; also provides physical linkage of the lipid bilayer to the underlying membrane skeleton. Constitutes about 25% of total membrane protein.
Band 3
Negatively charged RBC integral proteins that reduce the interaction of red cells with one another and with other cells.
Glycophorins
RBC integral proteins that serve as pores for water transport.
Aquaporin-1
RBC integral protein that facilitates diffusion of glucose into the cytosol of RBCs.
GLUT 1
RBC integral protein that actively transports Na+ out of the RBC and K+ in.
Na+/K+ ATPase (pump)
RBC integral proteins for transport of Na+, K+ and others.
Ion Channels & Exchangers
The most important function of ____ proteins is to provide the red cell with a flexible, yet mechanically resilient and stable membrane.
peripheral
Ankyrin, Protein 4.1, Protein 4.2, Spectrin
In humans, diseases such as _____ are caused by defects in the red cell proteins. It is characterized by the production of RBCs that are sphere-shaped rather than bi-concave disc shaped.
Hereditary Spherocytosis
At a partial pressure of O2 at 100 mmHg, hemoglobin is ____ saturated; O2 is bound to all four heme groups on all hemoglobin molecules.
98-100%
At a partial pressure of O2 at 40 mmHg, hemoglobin is ____ saturated which means that, on average, 3 of the 4 heme groups on each hemoglobin molecule have O2 bound.
75%
At a partial pressure of O2 at 25 mmHg, hemoglobin is ____ saturated which means that, on average, 2 of the 4 heme groups on each hemoglobin molecule have O2 bound.
50%
The sigmoid shape of the Hemoglobin Oxygen Dissociation Curve is a result of a change in the ____ of hemoglobin as each successive O2 molecule binds to the heme site. Called _____.
affinity
Positive Cooperativity
The following RBC maintenance processes require energy:
Red Cell membrane integrity Red Cell shape Hemoglobin sulfhydryl groups maintained in reduced forms Iron kept in reduced form Ion gradients
If there is insufficient energy, the RBC cannot maintain itself and it adopts a ____ shape.
spherical
Erythrocyte glucose metabolism depends exclusively on _____.
cytosolic proteins
3 important products of glucose metabolism are:
ATP
NADH
NADPH
____ is required to maintain Hemoglobin’s iron in the ferrous (reduced) state.
NADH
____ is required to maintain glutathione on the RBC membrane in its reduced form; reduced glutathione appears to be essential for maintaining normal red-cell structure and normal Hgb
NADPH
____ is the main source of energy for maintaining RBC ion gradients.
ATP
Through glycolysis, one molecule of glucose yields ___ molecules of ATP and ___ molecules of NADH.
2, 2
NADPH is produced through a process called the ____ (also called the ____) which is linked to glycolysis through ____.
Pentose Phosphate Pathway (also called the Hexose Monophosphate Shunt)
glucose-6-phosphate
The Pentose Phosphate Pathway is kicked off when Glucose-6-phosphate interacts with the enzyme ____ which yields a byproduct of ____.
Glucose-6-phosphate dehydrogenase
NADPH
Dead or deteriorating RBCs are removed from circulation by the ____ or ____. The waste product of RBC degradation is ____.
Liver or spleen
Bilirubin
The 3 major buffers in the blood are:
Carbonic Acid - Bicarbonate
Phosphate
Protein (hemoglobin, albumin)
How does blood act as a temperature regulator?
In cold temperatures the SNS stimulates vascular smooth muscle of skin blood vessels to constrict. Decreased blood flow to the surface of skin reduces heat loss.
In warm temperatures the SNS is inhibited causing vascular smooth muscle of skin blood vessels to vasodilator. Increased blood flow to the surface of the skin increases heat loss by radiation and convection. Shunting of blood to the surface is evidenced by redness and warmth of skin.
