Lecture 23: Heart Vessels and Microstructure Flashcards
What is hematopoiesis
The process by which hematopoietic stem cells (HSC) differentiate into blood cells
mobilization of hematopoietic stem cell
The process by which they can leave the bone marrow and enter the blood stream
Hematopoietic stem cells location
Found in bone marrow of mature adults,
How do we maintain hematopoietic stem cells (HSC) throughout life?
can undergo self renewal
How many RBC replaced every day
10x10^12
RBC life span
4 months, very short lived but they are the longest lived of all the blood cells.
yellow marrow vs. red marrow
red marrow contains HSC, yellow contains lipocytes
Three major types of blood cells and function
RBC –> Delivers oxygen to tissue
WBC –> Fights infection
platelets –> Clotting, maintaining hemostasis
Non-cellular component of blood, and its contents
Plasma: Electrolytes --> maintain tonicity Proteins --> albumin, globulin (antibodies), clotting factors Lipids Serum
What is an erythroblast?
It’s an immature RBC found in the bone marrow, still nucleated. Nucleus is excluded from the cell before it’s let out of the bone marrow into the blood. It can be polychromatophilic or orthochromatic (one step further in development, smaller nucleus, but in my opinion still looks purplish so idk why it’s called chrom.)
Polychromasia
RBC that has just left bone marrow, are larger and more purple under H&E because still producing protein in RER which it has to for hemoglobin
What stain precipitates RNA, what is it’s function
Methylene Blue, can tell polychromatic RBC apart from fully matured RBC bc RNA in RER precipitates out and looks like dark blue granules. Then called reticulocytes when imaged this way. Done for patients that could have anemia.
Size/shape of RBC, why are they this shape
The same size as WBC, but concave disk shown by white spot in the middle histologically. Helps increase surface area:volume ratio, which helps with gas exchange, and deformable which can help 7-8 micron diameter cells pass through 2 micron capillaries. Impaired deformability can be clinically relevant.
Components of normal RBC membrane
lipid bilayer, integral membrane proteins (chloride bicarbonate exchange), cytoskeleton proteins
erythrocyte qualities
Mature RBC.
Is anucleate and lacks organelles, which maximizes space for hemoglobin, but means that they have to use anaerobic respiration without mitochondria.
Hexose Monophosphate Shunt
Reduce oxidants, which are often the chemicals present in the blood, and could damage cells.
They also keep hemoglobin in a reduced state, for O2 binding.
Hemoglobin is made of?
What’s its function?
Two alpha globin chains and two beta globin chains, four heme molecules with with iron in center of each. Binds O2 and CO2, transports them between tissue and lungs. Very soluble in water compared to other proteins
Types of RBC irregularities
Sickle Cell anemia, Microcytes, Spherocytes, Elliptocytes
Thrombocytes
Another name for platelets
Megakaryocyte properties
Largest cell in the bone marrow, the cell doesn’t divide but is hyper-diploid as nucleus continues dividing into lobes, with each lobe being 2n.
How to megakaryocytes make cells
Parts of cytoplasm break off and become platelets
Platelet clumping
Happens in-vitro, is artifact of putting blood in test-tube. Causes platelet counts to be artificially low.
Platelet cellular properties
They are anucleur but have all of their organelles. Are filled with electron dense granules that stain acidophilically.
Microtubules are a canalicular system leading to the cell membrane, needed to release all of the granules into the blood systematically.
There are some contractile proteins (actin and myosin) and membrane proteins GP Ib, IIb, IIIa
Function of platelets
First line of defense in homeosis with blood loss caused by vessel injury–> Adhesion, Activation, Aggregation
Platform for fibrin/clot formation
Mediates inflammation, vascular constriction through releasing serotonin, and fibroblast production.
Thrombocytopenia
too few platelets
Another name for WBC
Leukocytes
Types of Leukocytes
Neutrophils (~60%, most prominent), eosinophil, basophil, monocyte, lymphocyte
Neutrophil properties
Also called polymorphonucleur leukocyte.
6 hr life span in blood, 1-5 days in tissue.
Multilobed nucleus, pink cytoplasmic granules.
Band neutrophil
One step less mature than neutrophil, has a horseshoe shaped nucleus. Can be seen in blood occasionally.
Function of neutrophils
Are able to mobilize to site of infection/inflammation, are attracted there by signaling proteins chemotaxins.
Phagocytosis/endocytosis, activated by antigen-IG complexes/coating.
neutrophilia
A high number of neutrophils in the blood
What causes neutrophilia
Endotoxin is released from the bacteria cell wall, and causes G-CSF and GM-CSF to be released from the marrow stromal cells which triggers neutrophilia
granulocytosis
Too many granulocytes, including neutrophils, can be caused by chronic myelogenous leukemia
Granulocytes
Neutrophil, Basophil, Eosinophil, NOT monocyte, NOT lymphocyte
Eosinophils qualities
Bilobed nucleus
Very pink granules in cytoplasm
Circulate for several hours then enter some skin/digestive/pulmonary mucus.
Function of eosinophil
Have receptors for IgE, and phagocytize antigen-antibody receptors. There are increased numbers in inflammation and allergic reactions.
