Blood consists of ___
Plasma and formed elements
Plasma (46-63%) composition
- Plasma proteins (7%)
- Other solutes (1%)
- Water (92%)- transports organic and inorganic molecules, formed elements, and heat
Plasma proteins
- Albumin (60%)- osmotic pressure; transport lipids, hormones, and steroids
- Globulins (35%)- transport immunoglobulins (antibodies) and other globulins
- Fibrinogen (4%)- essential for clotting
- Regulatory proteins (<1%)- enzymes, proenzymes, hormones
Other solutes
Electrolytes, organic nutrients, organic wastes
Formed elements (37%-54%)
- Platelets and white blood cells (0.1%)
- Red blood cells (99.9%)
Platelets
Fragments of megakaryocytes critical for clotting
WBC- leukocytes- defense against infection
- Neutrophils (50-70%)
- Eosinophils (2-4%)
- Basophils (<1%)
- Lymphocytes (20-30%)
- Monocytes (3-8%)
Red blood cells
Erythrocytes deliver O2 and remove CO2
Components of plasma: water
- More than 90% of plasma by volume
- Helps blood function as temperature buffer (absorbs heat)
Components of plasma: plasma proteins
- Albumin: too large to leave the bloodstream; regulate osmolarity and function as carrier molecules
- Globulins: also function as carrier proteins
- Clotting factors: play an essential role in blood clotting
- Water soluble hormones
___ ___ include cells and their fragments
Formed elements
Buffy coat
- Leukocytes <0.01%
- Thrombocytes <0.01%
- Erythrocytes 99.9%
Erythrocyte ___ complements functions
Structure
Biconcave shape allows RBCs to —
Bend, fold and stack to prevent blockage in tiny blood vessels
Biconcavity also increases ___
Surface area for gas exchange
Anucleate
Non-mitotic, carry very little DNA, unable to synthesize proteins
Erythrocytes are prone to ___
Apoptosis
___ is the process of red blood cell formation
Erythropoiesis
Erythropoiesis
- Hematopoietic stem cell
- Myeloid stem cell
- Proerythroblast
- Basophilic erythroblast
- Polychromatic erythroblast
- Orthochromatic erythroblast -> nucleus ejection
- Reticulocyte
- Mature erythrocyte
Erythropoiesis is ___
Increasing hemoglobin, organelle degradation, decreasing size of nucleus
Regulation of erythropoiesis by ___
EPO
Hypoxia and testosterone both ___
Signal EPO release
EPO drives ___
Erythrocyte maturation
Blood doping
Artificially inducing polycythemia by taking testosterone, EPO or highly-packed RBC suspensions
Anemia
Blood disorders characterized by the body's failure to supply tissues with adequate O2
___ reversibly binds to blood gases within erythrocytes
Hemoglobin
Features of hemoglobin
- Globular, tetrameric protein formed from 2 alpha and 2 beta chains (adult) or 2 alpha and 2 gamma chains (fetus)
- Each contains a heme group that binds oxygen using iron
- Binding sites for O2 are cooperative
Oxyhemoglobin
Bound to O2
Deoxyhemoglobin
No O2 bound
Sickle cell anemia
- Most common heritable blood disorder
- Mutation causes mis-folded beta chain, polymerization of hemoglobin and change of the RBC's shape
- Sickled RBCs are prone to clogging and have decreased ability to unload O2
Sickle cell anemia: causes
- Single point mutation in beta globin gene
- Passed on as a survival advantage in regions with high rates of malaria
Iron from erythrocytes is ___ ___ in the body
Carefully recycles
Fate of heme
- Heme converted to biliverdin, then bilirubin
- Bilirubin transported through plasma to liver; incorporated into bile
- In intestine, bilirubin is converted to stercobilin and incorporated into feces
Fate of iron
Iron is bound to transferrin, then transported to bone marrow for erythropoiesis
General characteristics of leukocytes
- Nucleated, have membrane-bound organelles, do not contain hemoglobin
- Move through amoeboid motion
- Move in response to chemical signals (chemotaxis)
- Form transient bonds to blood vessels using adhesion receptors (margination)
- Can slip between endothelial cells (diapedesis)
Neutrophils (physical characteristics)
- Large and polymorphonuclear
- Light purple when stained and viewed under microscope
Neutrophils
- Efficient killers of bacteria
- Granules contain hydrolytic enzymes, defensins (antimicrobial peptides) and lysozyme (digests bacterial cell wall)
Eosinophils (physical characteristics)
- Large with bi-lobed nuclei; stain bright red with acidic dye eosin
- Secrete four distinct cationic proteins that exert a range of effects
Eosinophils
- Combat multicellular parasites (ex: flatworms)
- Also contribute to allergies/asthma
Basophils (physical characteristics)
- Have bi-lobed nuclei; stain dark blue with basic dyes
- Granules contain histamine, serotonin, heparin and prostaglandins
Basophils
- Play a supporting role at sites of infection
- Also contribute to allergies and anaphylaxis
Lymphocytes (physical characteristics)
- Smallest leukocyte; have single nucleus
- Stain dark blue and purple
Lymphocytes
- B-lymphocytes: responsible for producing antibodies
- T-lymphocytes: defend against abnormal, cancerous or virus-infected cells
Monocytes (physical characteristics)
- Largest leukocyte; have U-shaped nucleus and stain dark blue and purple
Monocytes
- Exit circulation and transform into macrophages, which engulf foreign invaders by phagocytosis
- Can be grouped into inflammatory macrophages or non-inflammatory macrophages
Mononucleosis (kissing disease)
Causes:
- Infection: most likely EBV
- Virus is transmitted through saliva, semen and blood
Symptoms:
- Flu-like symptoms
- Virus causes T cells to enlarge as they fight infected cells, resembling monocytes
Blood type
Determined by carbohydrate markers on plasma membrane of erythrocytes
Positive blood type
Presence of Rhesus factor
Negative blood type
Absence of Rhesus factor
AB+
Universal recipient
AB-
Can receive blood from:
O-, A-, B-, AB-
B+
Can receive blood from:
O-, O+, B-, B+
B-
Can receive blood from:
O-, B-
A+
Can receive blood from:
O-, O+, A-, A+
A-
Can receive blood from:
O-, A-
O+
Can receive blood from:
O-, O+
O-
Universal donor
Can receive blood from:
O-
Hemolytic disease of the newborn
Attack of fetal RBCs by maternal immune system leading to miscarriage
Causes of hemolytic disease of the newborn
- Fetus is Rh+ while mother is Rh-
- First pregnancy sensitizes mother, so anti-Rh antibodies are present for second pregnancy
- Anti-Rh antibodies are small enough to cross the placental barrier
Treatment for hemolytic disease of the newborn
Injection of anti-Rh antibodies into mother (destroy Rh+ cells before immune system can notice them)
___ is the process of stopping blood loss
Hemostasis
1. Vascular spasm phase
Vasoconstriction
- Immediately after a vessel is damaged, smooth muscle constricts to limit blood flow
- Initiated by endothelin, tissue factor and ADP
2. Platelet plug formation phase
- Platelets arrive at the site of damage and adhere to sticky endothelium
- Release chemical messengers thromboxane A2, ADP, Ca2+ ions and clotting factors
- Form platelet plug
- Promote wound healing
3. Coagulation (clotting) phase
Reinforcement of platelet plug by web-like protein mesh formed by fibrin
4. Clot retraction (stable clot)
Platelets contract to make the clot more compact and pull wound edges closer together
Human blood clotting
- Clotting factors activate prothrombin
- Prothrombin activates thrombin
-Thrombin activates fibrinogen (soluble), becomes insoluble
- Fibrin strands adhere to the plug to form an insoluble clot
Clotting factors are synthesized in the ___
Liver- vitamin K dependent process
Factors secreted as ___ to avoid inappropriate clotting
Zymogens
Activation of thrombin is important ___
- Drives the coagulation phase
- Multiple pathways to activation
- The intrinsic and extrinsic pathways converge at the common pathway
Common pathway
- Prothrombin activates thrombin, which activates fibrin, which creates a stable cot
- Thrombin creates a positive feedback loop with clotting factors 12 and 11
Anticoagulant pathway
- Prevent clotting
- Thrombin and thrombomodulin
- Protein C becomes activated by thrombin and thrombomodulin which inhibits clotting factor 12 which activates the anticoagulant
Fibrinolytic pathway
- Break down clots
- Plasminogen gets activated by tissue plasminogen activator, activates fibrin