Constituents of blood Flashcards
what percent of our body is blood
7% of total body weight
5L (70kg male)
4L (58kg female)
what type of tissue is blood
connective
composition of blood
watery extracellular matrix (plasma ) 1/4 of body’s ECF
cellular elements: RBCs (erythrocytes), WBCs (leukocytes), platelets (thrombocytes)
Red blood cells
gas transport
- contain hemoglobin, drop off O2 at tissues
- biconcave and bendy
- no nucleus or mitochondria
main job of wbc
immune system
main job of platelets
prevent blood loss, clotting and hemostasis
buffy layer
platelets and which cells between plasma and rbcs
purpose of centrifugation
blood components can be seperated
hematopoesis
synthesis of blood cells, happens in bone marrow
Where does hematopoesis happen in adults
in bone marrow of pelvis, spine, ribs, cranial and proximal (closest to torso) ends of long bones
what percent of developing cells become rbcs and wbcs
25% RBCs
75% WBCs
life span of rbcs
120 days
life span of WBCs
6-12 hours
pluripotent hematopletic stem cells
undifferentiated precursors
megakaryocyte
gives rise to platelets
cytokines
control production and development of blood cells
proteins released from one cell affect the activity of another
types: erythropoletin and thrombopoietin
erythropoletin
made in the kidneys in response to decreased oxygen, influences growth of RBCs (working on bone marrow)
thrombopoletin
made in the liver, influences growth and differentiation of megakaryocytes
hypoxia
low oxygen levels in arterial blood
sensed by kidney cells which make erythropoletin which acts on progenitor cells in bone marrow to stimulate erythropolesis
result: increase number of RBC and increase oxygen capability in the blood
composition of hemoglobin
- made of four protein chains each centered around a heme group. Two alpha and two beta chains
- each heme group has a porphyrin ring with an iron atom in center
- O2 binds weakly to Fe
anemia
- low RBC count
- decreased hemoglobin content and reduced O2 carrying capacity of blood
accelerated rbc loss
- blood loss
- hemolytic anemia, busted blood
- RBC degradation > production
- genetic (sickle cell anemia) - protects against malaria
- aquired (malaria) - caused by a pathogen that infects and destroys blood cells
decreased RBC production
- aplastic anemia - lost ability to make new rbcs. drugs or radiation
- dietary insufficiencies
- iron, folic acid and vit b12 deficiencies
hemorrhage
loss of blood from vessels
hemostasis
keeping blood inside blood vessels
- want to keep this
steps to prevent blood loss
- vasoconstriction
- platelet plug formation
- Coagulation (formation of a clot)
- dissolution of clot (fibrinolysis)
vasoconstriction (to stop bleeding)
paracrine signals from endothelium
decreases blood flow and pressure in vessels
formation of a platelet plug
- edges of megakaryocyte break of to form cell fragments called platelets
- positive feedback, helps while more complex stuff happens
1. exposed collagen bends and activated platelets
2 release of platelet factors
3. factors attract more platelets
4. platelets aggregate into platelet plug
5. plug then converts into a fibrous clot via coagulation cascade
platelets will stick to collagen, the vessel wall contains collagen
fibrinolysis
tissue is repaired and clot dissolves due to actions of enzyme plasmin (responsible for breakdown)
blood type refers to..
the antigen express in RBCs
what happens when you are given the wrong blood type
agglutinate (clump)
AB (Rh+)
universal acceptor; no plasma antibodies
O (Rh-)
universal donar, no membrane antigens
Rh factor during pregnancy
- Rh+ father
- Rh- mother carrying her first Rh+ fetus. Rh antigens from the developing fetus can enter the mother’s blood during delivery
- In response to the fetal Rh antigens, the mother will produce anti-Rh antibodies
- If the woman becomes pregnant with another Rh+ fetus, her anti-Rh antibodies will cross the placenta and damage fetal red blood cells
hemolytic disease of newborn
how to prevent Rh factor
inject mother with anti-Rh antibodies before birth of first born
attacks contaminating Rh+ fetal blood before mother can develop her own immune response
