physiology week 9 Flashcards
-RBC,Anemia and polycythemia
What is the primary role of red blood cells
- Transports hemoglobin, which carries oxygen from lungs to tissues
Why must the hemoglobin remain inside the red blood cells
- To avoid loss through the capillary and kidney membranes
What else does red blood cells contain
- Carbonic anhydrase, which is an enzyme that catalyses the conversion of C02 and water into carbonic acid
What are the roles of carbonic anhydrase
- An enzyme that catalyses the conversion of c02 and water into carbonic acid
- It enables efficent C02 transport as bicarbonate ions
- Contributes to acid-base buffering in the blood due to hemoglobin properties
What is the shaoe and size of RBC
- Has a biconcave disc
- Volume of 90-95 cubic meters
- Has a flexible bony like structure which allows the deformation for passage through capillaries without rupture
What are the sites of red blood cell production in the embroyonic stage:
-Early weeks
-Middle trimester
-Last trimester+ after birth
- Early weeks:
-Primitive nucleated red blood cells are produced in the yolk sac
Middle trimester
-The liver is the primary ogran for RBC and some is also produced in the spleen and lymph
LAST TRIMESTER & AFTER BIRTH
-RBC production shifts to the bone marrow
During childhood where are red blood cells produced
- In the marrow of nearly all bones up to 5 years of age
During Adulthood where is red blood cells produced
- In the membranous bones:
-Vertberae
-Sternum
-Ribs
-ilia
What is the aging effect in relation to bone marrow
- Bone marrow productivity decreases as age increases even in membranous bones
Where do circulating red blood cells orginate from
- Multipotential hematopoietic stem cells (HSCs) in the bone marrow
- The stem cells self renew to maintain their supply, but their numbers decrease with age
What happens as HSCs( hematopoietic stem cells) reproduce
-Most cells differentiate into specific cell types while a small portions remains a HSCs
- Where do commited cells arise from
- They arise from multipotent stem cells
Whay do commited stem cells produce
- They produce colonies of specific blood cells such as
- CFU-E , which forms erythrocytes)RBC)
-CFU-GM, which formes granulocytes and monocytes
What are growth inducers
And how many exist
- They are proteins that control growth and reproduction of stem cells
- At least 4 major growth inducers exist
Name an example of a growth inducer and its role
- Interleukin -3 and it promotes the growth of nearly all types of committed cells
What are differentiation inducers
-Proteins that control differentiation of stem cells into specific blood cell types.
Each differentiation inducer acts on a specific committed stem cell.
Name factors outside the bone marrow that regulate growth and differentiation
–Low oxygen levels which increases RBC production
-Infections which stimulates production of specific white blood cells to combat the infection
Name briefly the main stages of RBC formation
- Proerythroblast formation
- Cell division
-3 stages of development - Condensation of the nucleus and removal of organelles
- Reticulocyte stage
-Maturation ino erythrocytes
Explain Proerythroblasts formation
step(1)
- The proerythroblasts are the first identifable cells in the RBC lineage
- And they orginate from CFU-E stem cells
Explain the cell division process in the formation of RBC
step 2
- Proerythrocytes divide multiple times producing several generations,
- The first generation is called Basophil erythroblasts
Explain the process that happens in the stages of development
step 3
- Basophil erythroblats is the first generation , in which its named for its ability to stain with basic dyes
- Then the second stage is Polychromatophil erythroblasts, which is wehere hemoglobin synthesis occurs
What stage happens After the 2 stages of development in producing RBC
step 4
CONDENSATION OF NUCLEUS AND REMOVAL OF ORGANELLES
- As the cells mature,
-hb concentration increases
-Nucleus condenses into a small size
- And organelles such as ER are reabsorbed
What happens in the reticulocyte stage
step 5
- The cells become a reticulocyte
- Reticuolcytes contain remnants of organelles and a small amount of basophillic material
- Then they enter the bloodstream via diapedesis( movement through capillary pores)
Name the 2 stages in the stages of development for production of RBC
- Basophil erythroblasts
-Polychromatophil erythroblasts
How is a mature erythrocyte formed
- W/n 1-2 days the remaining basophillic material disappers and the cell becomes a mature erythrocyte
What is the purpose of red blood cell regulation
- It ensures sufficient red blood cells to transport oxygen to the tisues without impending blood flow
Name three stimulis for RBC production
- Anemia
-High altitudes
-Circulatory diseases
What is the role of Erythropoietin
and hypoxia
- It is a glycoprotein hormoe that is essential for RBC production under hypoxia
- Hypoxia triggers erythropoietin production which stimulates RBC formation until oxygen levels become normal
What is the site of Erythropoietin production
- About 90 % in the kidneys, which is secreted by fibroblast-like interstitial cells in the cortex and medulla and the rest in the liver
Explain the mechanism of how Erythropoietin causes RBC production
-It stimulates the formation of proerythroblasts from hematopoietic stem cells
-Then, its speeds up the progression of the proerythroblasts through the embyonic stages
What does the absence of Erythropoietin lead to
- Reduced minimal RNC production
What is Vitamin B12 and Folic Acid essential for?
- DNA synthesis, forming thymidine triphosphate
What does a deficiency in V12 and Folic acid lead to
Maturation failure Anemia
Where is Folic Acid found in
Green vegetables,liver,fruits
What disorder is Folic Acid deficiency associated with
- Gastrointestinal absorption disorders like sprue
What does deficient erythropoiesis produce
It produces large,irregular RBCs called macrocytes
whcih have fragile membranes and shorter life span
What causes deficient erythropoiesis
Deficiency on folic acid or V12
Where does hemoglobin synthesis begin and continue
- Begins in polychromatophil erythroblasts and continiues into the reticulocyte stage
What is the role of retoculocytes in hemoglobin formation
- Synthesize small amounts of hemoglobin 1 day before maturing into erythrocytes
Explain the chemical steps in Hb formation
-Succinyl-CoA combines with glycine to form pyrrole.
-Four pyrroles form protoporphyrin IX, which binds with iron to create heme
-Each heme combines with a polypeptide chain (globin) to form a hemoglobin subunit.
-Four subunits combine to form a complete hemoglobin molecule.
Name the 4 types of Hb chains
- Alpha
-Beta
-Gamma
-Delta
What does adult hemoglobin consist if
2 alpha and 2 beta chains
How many heme groups does hb have and its role
- Has 4 heme groups, this allows it to carry 4 ocygen molecules
Explain Hb binding to oxygen
- It binds to oxygen loosely and reversibly
What is the total amount of iron in the body
- 4-5 g
Explain iron distribution in the body
65% in Hb
4% in myoglobin
1% in heme compounds
15-30% is in ferritin
How is iron transported
- It binds to apotransferrin in the blood to form transferrin
-Transferrin carries iron into the plasms and delivers it to the tossues where it is needed
Where is excess iron stored
- Reticuloendothelial cells
Name and desribe the 2 ways in which iron is stored
- Ferritin: Main way to store iron
- Hemosiderin: Insoluble from of storing iron
How is iron recycled
- After 120 days, aged/old RBCs are destroyed and hb is broken down by moncyte-macrophage cells
- ## The iron is released and stored in the ferritin pool
What is Anemia
A deficiency of hemoglobin in the blood, caused by few or insufficient RBCs in the cell
Name the types of Anemia
- Blood loss Anemia
-Aplastic Anemia
-Megaloblastic Anemia
-Hemolytic Anemia
What is Aplastic Anemia caused by
- Bone marrrow dysfunction often due to Toxic chemicals
What is Megaloblastic Anemia caused by
- Caused bye a deficiency in Vitamin B12,folic Acid
What is secondary Polycythemia triggered by
and what does it cause
Tissue hypoxia due to low oxygen levels
- Causes increased RBC
What affects does Anemia have on the circulatroy system
- Reduced viscosity
-Increased work load on the heart
What is polycythemia vera
what does it result in
- A pathological condition due to genetic mutation in the blood
- uncontrolled RBC production
- Leads to excessive WBC and platelets production
What are the effects of polycythemia on the circulatroy system
-Increased blood Viscosity
-Increased blood volume
What is the function of leukocytes
- To combat infection and inflammation
Where are the formation sites of Leukocytes and explain what they produce
- Bone Marrow: produces granulocytes,monocytes and lymphocytes
-Lymph tissue:produces lymphocytes and plasma cels
Name 3 types of leukocytes
- Monocytes
-Plasma cells
-lymphocyte
What is the function of granulocytes and moncytes
- Release inflammatory substances
What is the function of platelets
Activate blood clotting
Name the two lineages of white blood cells
- Myelocytic lineage
-Lymphocytic lineage
Desribe the 2 lineages of the WBC and what they produce
-Myelocytic Lineage: Starts with myeloblast and produces granulocytes and monocytes.
-Lymphocytic Lineage: Starts with lymphoblast and produces lymphocytes and plasma cells.
What are platelets known as
- Thrombocytes
What are platelets formed from
Fromed from megakarycoytes fragments in the bone marrow
What is the life span of Plasma cells( Thrombocytes)
10 days
What is the life span for granulocytes
4-5 days
What is the life span for monocytes
10 - 20 hrs
What is the role of neutrophils in Defense
Destroy and attack bacteria in the blood streams
What are macrophages
Originate as blood monocytes
How des neutrophils and monocytes enter the cells
Squeeze through the gaps between the endothelial cells in the capillaries and venules
Why do neutrophils and macrophages use Ameboid motion
They use it to travel through the tissue
Explain WBC attraction to inflamed areas by chemotaxis
and examples of chemicals released
WBCs are directed towards inflamed areas by chemical gradients of substances released during inflammation, including
- Bacterial or viral toxins
What is phagocytosis
The ingestion of harmful agents by neutrophils and macrophages
Name 3 selective mechanism used in allow better phagocytosis
-Surface texture
- Protective coats
- Opsonization
Explain the purpose of surface texture as a selective mechanism in phagocytosis
- Rough surfaces enhances phagocytosis
Explain the purpose of protective coats as a selective mechanism for phagocytosis
Substance have protective coating that repel phagocytes , whereas dead tissues or foreign particles do not have these coats making them vulnerable
What is the purpose of Opsonization as a selective mechanism in phagocytes
Antibodies and complementary proteins like C3 mark pathogens for phagocytosis
Explain the mechanism of Phagocytosis
Mechanism of Phagocytosis:
-Neutrophils and macrophages use pseudopodia to surround and engulf particles, forming a phagosome.
-The phagosome fuses with lysosomes to create a phagolysosome, where the ingested material is digested.
Explain phagocytosis by neutrophils
- what are they specialised for
- Nuetroohils are fast acting phagocytes that ingest 3-20 bacteria before dying
- they are specialised for small particles like bacteria
Explain phagocytosis by macrophages
Phagocytosis by Macrophages:
-Macrophages, derived from monocytes, are more powerful and long-lasting than neutrophils.
-They can engulf larger particles, such as red blood cells or malarial parasites, and survive after digesting particles.
Explain how phagocytized particles are digested
Digestion of Phagocytized Particles:
Lysosomes release digestive enzymes into the phagosome to break down the ingested material.
Macrophages have additional enzymes, like lipases, for digesting lipid-rich bacterial membranes.
How does the neutrophils and macrophages kill bacteria resistant to enzymatic digestion
Neutrophils and macrophages produce bactericidal agents (e.g., superoxide, hydrogen peroxide, hydroxyl ions) that kill bacteria resistant to enzymatic digestion.
What happens to the histiocytes in the skin
- Divide locally to combat infections and destroy pathogens
What does the reticuloendothelial system include
- Monocytes
-Mobile macrophages
-Fixed macrophages
What is the function of the macrophages in the lymph nodes
- Trap particles from lymph
What is the function of the kupffer cells in the liver
- Filter bacteria from portal blood
What is the function of the Aveolar macrophages in the lungs
They phagocytize particles in the lungs
What is inflammation
- Tissue injury from bacter,chemicals or heat
What are3 key features of inflammation
- Tissue swelling
-Vasodilation
-Clotting
What is the purpose of the Walling-of Effect
To block the spread of bacteria by forming fibrin clots
What is the first line of defense
what is the second line of defense
what is the third line of defense
Tissue Macrophages
Neutrophils
Macrophage invasion
What components does Pus contain
- Macrophages
-Tissue fluid
-Dead neutrophils
Name the 3 mechanisms in which neutrophils invade
-Margination
-Diapedesis
-Chemotaxis
What is the primary role of Eosinophils in
Parasite infections
What is the function of basophils
- similar to mast cells
release seratonin
histamine
What is the role of basophils in Allergies
-React with igE antibodies release
What is Leukopenia
- Low production of WBC by the bone marrow
What causes leukopenia
- drugs,radiation
What are the treatments for leukopenia
- Antibiotics
What is leukemia
- Uncontrolled production of WBX due to cancerous mutation
Name the 2 types of leukemia
-lymphocytic leukemia
-Myelogenous leukemia
