Chapter 17 - blood Flashcards
What are the functions of blood?
- transport
- regulation
- protection
What does the blood transport?
delivers O2 and nutrients to the body
- transport metabolic waste to lungs and kidney
- transports hormones from endocrine to target organs
How does blood regulate?
- maintains body temp by absorbing and distributing heat
- maintains pH levels (through alkaline reserve of bicarbonate ions)
- fluid volume in circulatory system
How does blood protect?
prevent blood loss
- plasma proteins and platelets in blood initiate clot formation
prevent infection
- antibodies
- complement proteins
- WBC
What are the components in blood?
- RBC (erythrocytes)
- WBC (leukocytes)
- plasma
- tissue fibers (fibrin - only appears when clotting)
What are the layers of blood after being spined?
Plasma (55%)
- least dense component
Buffy coat (<1%) - formed blood
- leukocytes and platelets
Erythrocytes (45% - hematocrit - whole blood consisting of RBC) - formed blood
- most dense
Plasma overview (3).
- Straw-colored, sticky fluid
- Composed of 90% water
- Contains over 100 dissolved solutes
What are the dissolved components in plasma?
- Nutrients
- Gases
- Hormones
- Wastes
- Proteins
- Inorganic ions
What is plasma protein and its function
- Most abundant solutes by weight (8% of plasma)
- Primarily produced by the liver (except antibodies and hormones)
- Functions: carries out functions (not taken up by cells for fuel)
What are the features of erythrocytes?
- small-diameter lacking nucleus (anucleate) and most organelles
- filled with hemoglobin (Hb)
- intracellular network of structural protein (actin and spectrin) can be deformed by myosin to change cell shape
What is albumin and its function?
Comprises 60% of plasma proteins
Major functions:
- Blood buffer (regulates blood pH)
- Carrier (transports certain molecules)
- Contributes to plasma osmotic pressure (retains water in blood)
What are formed elements and what is the special features?
- Composed of erythrocytes (RBCs), leukocytes, and platelets.
They are not true cells - RBCs lack nuclei and organelles; platelets are cell fragments.
- Most formed elements survive only a few days.
- Blood cells do not divide; they are replaced by stem cells in red bone marrow.
What are the reasons RBC is a good gas exchanger and transporter?
- biconcave disc (most surface area to volume ratio) - short diffusion distance
- Hb makes up 97% of cell volume (excludes water)
- no mitochondria means no oxygen consumption (ATP made in cytosol anaerobically)
Explain the function and content of hemoglobin.
- bonds reversibly with oxygen
- consists of red heme pigments bound to the protein globin (made of 4 subunits - 2 alpha and 2 beta polypeptide; heme group with central iron ion)
- 1 hemoglobin can bind 4 O2
What are the names for how O2 and CO2 bind to RBC?
- oxyhemoglobin (bight red - O2 binds)
- deoxyhemoglobin (dark red - O2 detaches)
- carbaminohemoglobin (20% of CO2 in blood binds to Hb)
What is hematopoiesis?
formation of blood cells in the red bone marrow
- made of reticular CT with large capillaries (blood sinusoids)
- mature BC cross into blood through pores
What is hematopoietic stem cells?
hemocytoblasts
- hormones and growth factors push cells to commit to specific blood cell pathways
- committed cell can’t change pathway
What is erythropoietin (EPO)?
- hormone that stimulates the production of red blood cells (erythropoiesis).
- present in blood at low amount to maintain a basal rate of RBC production.
- When kidney cells experience low oxygen levels (hypoxia), they release more EPO.
- This happens because oxygen-sensitive enzymes in these cells can’t break down a protein called hypoxia-inducible factor (HIF), allowing HIF to build up and trigger increased EPO secretion (positive feedback).
What are the causes of hypoxia?
- decreased RBC for bleeding or destruction
- iron deficiency (not enough hemoglobin/ RBC)
- reduced O2 availability
What inhibits EPO and what is its effects on target cells?
- by high levels of O2 or excess RBC
- targets cells that do erythropoiesis and accelerate their maturation
- testosterone enhances EPO production; higher hematocrits in makes
What are the dietary requirement for erythropoiesis?
Nutrients:
- Amino acids, lipids, carbohydrates
B-Complex Vitamins:
- Vitamin B12 and folic acid for DNA synthesis in developing RBCs
Iron:
- Essential for hemoglobin synthesis
- 65% found in hemoglobin; rest in liver, spleen, bone marrow
- Stored in cells as ferritin and hemosiderin (protein iron complex)
- bound to transferrin in blood for transportation
Explain RBC life cycle.
- 100-120 days
- old RBC are fragile with Hb beginning to break
- can get trapped in spleen (engulfed by macrophages)
How is RBC broken down?
Separates into:
iron (binds with ferridin or hemosiderin - stored)
- heme (degraded into bilirubin produced by liver and transported to feces)
- globin (metabolized into amino acids; released into circulation)
What is sickle cell caused by?
a mutation in hemoglobin S (HbS)
- less likely to bind O2 and is fragile
- shorter life span
How is blood doping used by athletes?
- artificially induce polycythemia (blood doping) to boost oxygen-carrying capacity.
- enhances aerobic performance.
What are the methods of blood doping?
Injecting EPO: Increases hematocrit.
RBC Reinfusion:
- Remove and store RBCs, then reinfuse later.
- Stored RBCs are replaced by new ones, increasing overall hematocrit upon reinfusion.
What are the risks of blood doping?
- EPO raises hematocrit from 45% to 65%.
- Dehydration can further concentrate blood.
- Risks include blood becoming viscous, leading to clotting, stroke, or heart failure.
In platelets, what are some chemicals involved in the clotting process?
- serotonin. calcium, enzymes, ADP, PDGH
How are platelets kept inactive when not needed?
- By nitric oxide (NO) and prostacyclin from endothelial cells in undamaged vessels.
What are platelets lifespan and formation?
- Age quickly; degenerate in about 10 days.
- Formation (thrombopoiesis) regulated by thrombopoietin.
What is the normal platelet concentration?
150,000–400,000 platelets/mL.
Where are platelets formed?
Bone: Megakaryocytes send projections into red bone marrow capillaries, breaking off into platelets.
Lungs: Megakaryocyte fragments travel to lungs, getting trapped in pulmonary capillaries and fragmenting into more platelets (over half of circulating platelets).
What is hemostasis and 3 steps?
Definition: Process to stop bleeding - localized.
Steps:
1. Vascular spasm
2. Platelet plug formation
3. Coagulation
What is vascular spasm?
Smooth muscle contracts, causing vasoconstriction.
Triggered by:
- Direct injury to vascular smooth muscle
- Chemicals from endothelial cells and activated platelets
- Pain reflexes
Effectiveness: Most effective in smaller blood vessels; reduces blood loss, allowing time for subsequent steps.
What is platelet plug formation?
- Injury exposes collagen; platelets adhere and activate.
- von Willebrand factor aids adhesion; prostacyclin and nitric oxide prevent unwanted sticking.
- Activated platelets release ADP, serotonin, and thromboxane A2, enhancing aggregation.
- Effective for small tears; larger breaks require more steps.
What is coagulation and 4 key points?
Fibrin proteins form a mesh, trapping RBCs and platelets to create a clot.
Key Points:
- Reinforces platelet plug.
- Involves clotting factors (I to XIII), mostly liver proteins.
- Vitamin K is essential for some clotting factors (turns them into enzymes for next step).
- Occurs in three phases.
What is the first phase of coagulation?
pathways: intrinsic and extrinsic
I - Clotting factors present within the blood.
E - Clotting factors located outside blood - faster
What is the second phases of coagulation?
intrinsic and extrinsic pathways merge
- prothrombin becomes thrombin
What is the third phases of coagulation?
- thrombin and Ca2+ fibrinogen turns into fibrin, which links to form strands and stabilizing fibrin fibers
anticoagulants: substance that inhibit clotting
What enzyme catalyzes prothrombin –> thrombin and fibrinogen –> fibrin?
- prothrombinase
- Thrombin
What are the roles and effects of antigens?
- trigger immune responses when perceived as foreign.
- Mismatched transfusions can cause agglutination and destruction of RBCs.
explain antigens and agglutinogens.
- RBC antigens that promote agglutination are called agglutinogens.
- Humans have at least 30 naturally occurring RBC antigens.
- A, B, and Rh antigens cause the most vigorous transfusion reactions.
What is the role of anti bodies in the bloods?
- contains anti-A and/or anti-B antibodies (agglutinins).
- Group O: both anti-A and anti-B antibodies.
- Group A: anti-B antibodies
- Group B: anti-A antibodies
- Group AB: no antibodies.
