Chapter 17 - blood Flashcards
(43 cards)
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
