PSL301 Blood Summary Notes

Lec 1: Intro and Red Blood Cells

Functions of Blood
 Transports gases, nutrients, hormones and metabolic wastes
 Regulates composition of interstitial fluid (e.g. pH, ions, water, etc)
 Restricts fluid loss at entry sites via blood clotting
 Defends against toxins and pathogens
 Regulates body T by absorbing and redistributing heat depending where in the body
blood goes
Constituents of Blood
 Hematocrit = % of total blood volume occupied by packed centrifuged red blood
cell, WBC, and platelets (normal “Formed Element”: 37~54%)
 Plasma = the rest of the blood, mainly water (92%) along with other ions, organic
molecules including a.a., proteins (albumins, globulins, fibrinogen), lipids, nitrogenous
waste), trace elements and vitamins, and gases
o Post plasma proteins made by liver
Functions of Plasma Proteins
- general: generate colloid osmotic pressure
o i.e. provide osmotic active particles to keep fluid in blood stream
o buffer pH (H+ binds to the a.a. of proteins and act as buffer)
- specific:
o albumins: colloid osmotic pressure; carriers of hormones & other
organic molecules; most abundant
o globulins: group of proteins that run in sections (a, B, y) in gel
 Alpha & Beta: clotting factors, enzymes, carriers
 Gamma: antibodies
o Fibrinogen: forms fibrin for blood clotting
Formed Elements
- 99.9% = RBC = Erythrocytes
- 0.1% = WBC = leukocytes
- Lymphocytes, monocytes, neutrophils, eosinophils, basophils
o Monocytes & Neutrophils considered ‘phagocytes’
o Neutrophils & Eosinophils & Basophils considered ‘granulocytes’ due to
the granules & vesicles
o the relative ratio / number of leukocytes can give an idea for possible illness
- rest = platelets = thrombocytes

Origin of Cells in blood
- embryo  yolk sac, liver, and bone marrow

, - after birth  bone marrow (inside the bone)
o surrounds the central sinuses, stroma of marrow,
and nutrient artery o in pelvis, spine, ribs, cranium,
proximal end long bones (thigh bones)

- 1/10,000 cells: pluripotent hematopoietic stem cell
- uncommitted stem cellcommitted progenitor cells OR
lymphocyte stem cells(look diagram)
- In bone marrow, 25% are developing RBC, and 75% are developing
WBC
- Immature blood cells matures fully as it enters circulation
(examples…)
o Reticulocyte  erythrocyte
o Megakaryocyte  platelets
- Regulation by Cytokines (the growth/ differential factors)
o Colony Stimulating factors (CSF): from endothelial cells and
WBC
 Ex. G-CSF (granulocyte CSF) for neutrophil and monocyte
 G-CSF used in clinical setting during
chemotherapy to increase the number of
neutrophils and help the immune system
o Interleukins: from WBCs
 The two affect survival, proliferation and
differentiation of different cell types
o Erythropoietin (EPO): stimulates erythrocytes;
made in kidney o Thrombopoietin (TPO):
stimulates megakaryocytes; made in liver

Red Blood Cells
- ‘cells’ / bags filled with hemoglobin and enzymes
- functions by anaerobic metabolism
- no nucleus = no new transcription
- life span: 120 days
- 5 x 10^12 cells/L of blood
- contains Hemoglobin (four polypeptides with a heme group + iron)
- changes shapes to fit into small capillaries

, - 2~3 million/second made in the body
- “Erythropoiesis” regulated by EPO
o EPO synthesized and released from kidney, bit in liver in
response to low O2
o Nucleus pinches off and mitochondria & ER break down
o Proerythroblast  Polychromatophlic erythroblast
 Normoblast  Reticulocyte (enters circulation)
 Mature erythrocytes
- Removal
o Engulfed by Macrophages in spleen, liver, bone marrow
o Heme broken down to Bilirubin, Iron recycled