Hematopoiesis Flashcards
RBCs
- Structure
- Function
Structure: Non-nucleated
Function: Carries Hb which carries O2 to tissues
WBCs
- Structure
- Function
Structure: Nucleated
Function: Fights infection and/or provide immunity
Platelets
- Structure
- Function
Structure: Fragment of cytoplasm from its precursor cell
Function: Forms platelet plug to stop bleeding (doesn’t matter how severe)
3 phases of fetal hematopoiesis
- Mesoblastic phase
- Hepatic phase
- Myeloid phase
Mesoblastic phase
- Anatomic site of active cell production
- Gestational period of active cell production
- Occurs in yolk sac
- Begins at day 19 to week 5
- Only RBCs forming (Gower Hb), no WBCs
Hepatic phase
- Anatomic site of active cell production
- Gestational period of active cell production
- Liver (major site), but also spleen, LN, and thymus
- Week 5 to month 5
Myeloid phase
- Anatomic site of active cell production
- Gestational period of active cell production
- BM
- month 5 to birth
Normal red and yellow marrow distribution
- Newborn
- BM is 100% cellular
- More RBCs (more Hb) circulating compared to WBCs
Normal red and yellow marrow distribution
- Child (~5-7 years old)
- Doesn’t need as many circulating cells but needs more bone development
- Marrow starts receding at distal portions of long bones and gets replaced by yellow marrow/fat
Normal red and yellow marrow distribution
- Adult (~18 years old)
- 7 active sites of hematopoiesis
- Cellularity = 100 – patient’s age
7 sites of hematopoietic tissue in the normal adult
- Skull
- Shoulder blades
- Sternum
- Ribs
- Vertebrae
- Pelvis (most common)
- Proximal portions of long bones
3 anatomic sites of extramedullary hematopoiesis in order of frequency of involvement
- Spleen (most common)
- Liver
- LN
* NEVER THE THYMUS!
Reactive form of extramedullary hematopoiesis
We know the reason
Non-reactive form of extramedullary hematopoiesis
We don’t know the cause
Location of hematopoietic marrow
B/w or outside of venous sinuses (sinusoids)
Cell lines derived from CFU-GEMM
- Granulocytes
- Erythrocytes
- Monocytes
- Megakaryocytes
5 morphological changes that occur in most cells in response to cell maturation
- ↓ in cell size
- ↓ in nucleus: cytoplasm ratio
- Loss of nucleoli (lose by 2nd if not 3rd stage)
- Loss of cytoplasmic basophilia (RNA)
- Nuclear chromatin pattern (DNA) → fine to coarse
4 ways that BM can respond to increased demand fro blood cells
- Maturation time can be decreased
- Decrease in generation time
- Expand into fatty areas of red marrow
- Expand into yellow marrow
* Last resort…extramedullary hematopoiesis (spleen → liver → LN)
Major function of cell membrane
- Separates cell from outside environment
- Detects hormonal signals facilitating cell-to-cell recognition
- Location of surface markers (CD markers) for cell identificaiton
Major function of Golgi complex
- Packages and sorts cellular products = “directs traffic”
- Lies next to nucleus
Major function of endoplasmic reticulum
Stores and transports fluids
Major function of ribosomes
- Site of protein synthesis = RNA
- Gives cytoplasm blue color in less mature cells
Major function of mitochondria
Energy source for cells
Major function of lysosomes
Contains hydrolytic enzymes that aid in cellular digestion during phagocytosis
Major function of nucleolus
Site of synthesis of ribosomal RNA
