2023-11-29T20:52:06+03:00[Europe/Moscow] en true <p>An RBC is essentially a bag of...?</p>, <p>What is the average diameter of an RBC? Is it able to deform?</p>, <p>What 3 things does the cell membrane consist of?</p>, <p>What are the % proportions of these components of the Red cell membrane?</p>, <p>What is the structure of the red cell membrane?</p>, <p>What are the lipid components of the red cell membrane?</p>, <p>What are the % proportions of these components of the lipid Red cell membrane?</p>, <p>State some information about phospholipids and the Membrane (7 points)</p>, <p>What are integral membrane proteins?</p>, <p>What are the 2 major integral membrane proteins?</p>, <p>Other integral proteins include....?</p>, <p>What are peripheral proteins?</p>, <p>Major peripheral proteins include:</p>, <p>What is spectrin?</p>, <p>What is Ankyrin?</p>, <p>What is protein 4.1?</p>, <p>What is Actin?</p>, <p>What are carbohydrates?</p>, <p>State ATLEAST 5 different monosaccharides that are found on the red cell membrane</p>, <p>What determines are blood group?</p>, <p>Statement: The Majority of antigens are carbohydrates. Is this true or false?</p>, <p>Picture illustrating idea in previous flashcard:</p>, <p>What is the primary function of RBC? And how is this achieved?</p>, <p>List 4 characteristics of the RBC and their importance</p>, <p>Statement: Membrane cholesterol exists in free equilibrium with plasma cholesterol.... True or false?</p>, <p>An increase in free plasma cholesterol results in an accumulation of what in the RBC membrane?</p>, <p>RBCs with increased cholesterol appear distorted, which results in the formation of..........?</p>, <p>An increase in cholesterol and phospholipid is due to what?</p>, <p>What are the two possible defects in the RBC membrane?</p>, <p>What is Hereditary Spherocytosis caused by?</p>, <p>What is Hereditary Elliptocytosis caused by?</p>, <p>Picture demonstrating the various RBC shapes and sizes:</p>, <p>State some information about Haemoglobin structure</p>, <p>What is the Adult amounts of haemoglobin in adults (both male and female)?</p>, <p>What does Haemoglobinopathies mean?</p>, <p>Inherited disorders of Hb can be split into 2 categories: what are these categories </p>, <p>What are the two main metabolic pathways?</p>, <p>What are the two main enzymes associated with these pathways?</p>, <p>State some information about the Glycolytic pathway (PK enzyme)</p>, <p>Outline the series of reactions in the glycolytic pathway</p>, <p>What is a PK deficiency, and what happens during a PK deficiency?</p>, <p>State some information about the pentose phosphate pathway</p>, <p>Outline the series of reactions in the pentose phosphate pathway</p>, <p>What is another name for the Pentose phosphate pathway?</p>, <p>What causes a G6DP deficiency?</p>, <p>What does a G6DP deficiency do?</p>, <p>A general summary for this lecture:</p> flashcards

The Red Blood Cell structure and function (Pathology)

Further reading: https://www.ncbi.nlm.nih.gov/books/NBK9898/

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  • An RBC is essentially a bag of...?

    Haemoglobin

  • What is the average diameter of an RBC? Is it able to deform?

    8 microns in size, and is able to deform and pass through 3 micron capillaries or reticuloendothelial system without fragmentation.

  • What 3 things does the cell membrane consist of?

    -Proteins

    -Lipids

    -Carbohydrates

  • What are the % proportions of these components of the Red cell membrane?

    -Proteins (50%)

    -Lipids (40%)

    -Carbohydrates (10%)

  • What is the structure of the red cell membrane?

    -A semi-permeable lipid bilayer; with proteins scattered throughout:+an outer hydrophilic portion composed of glycolipids. Glycoproteins and proteins+A central hydrophobic layer containing proteins, cholesterol and phospholipids+An inner hydrophilic layer of mesh-like cytoskeletal proteins to support lipid bilayer

    -A semi-permeable lipid bilayer; with proteins scattered throughout:

    +an outer hydrophilic portion composed of glycolipids. Glycoproteins and proteins

    +A central hydrophobic layer containing proteins, cholesterol and phospholipids

    +An inner hydrophilic layer of mesh-like cytoskeletal proteins to support lipid bilayer

  • What are the lipid components of the red cell membrane?

    -Phospholipids

    -Cholesterol

    -Sphingolipids

  • What are the % proportions of these components of the lipid Red cell membrane?

    -Phospholipids (60%)

    -Cholesterol (30%)

    -Sphingolipids (10%)

  • State some information about phospholipids and the Membrane (7 points)

    -Have fatty acid tails that are hydrophobic

    -Have a phosphate group head that is hydrophilic

    -Arranged in a bilayer

    -Asymmetric phospholipid distribution

    -Unesterified free cholesterol between

    -Uncharged phospholipids of outer layer (Phosphatidyl choline and Sphingomyelin)

    -Charged phospholipids of inner layer:

    +Phosphatidyl ethanolamine

    +Phosphatidyl serine

  • What are integral membrane proteins?

    They extend from the outer surface and traverse the entire lipid bilayer membrane to inner surface

  • What are the 2 major integral membrane proteins?

    -Glycophorins:A, B and C

    -Band 3: anion transporter

  • Other integral proteins include....?

    Na+/K+ ATPase, Aquaporin 1, surface receptors, e.g. TfR

  • What are peripheral proteins?

    -Limited to cytoplasmic surface of membrane and forms the RBC cytoskeleton

    -The cytoskeleton acts as a tough framework to support the bilayer responsible for deformability and maintains biconcave shape.

  • Major peripheral proteins include:

    Spectrin, Ankyrin, Protein 4.1 and Actin

    Spectrin, Ankyrin, Protein 4.1 and Actin

  • What is spectrin?

    -The most abundant peripheral protein-Composed of alpha and beta chains-Very important in RBC membrane integrity+Binds with other peripheral proteins to form the cytoskeletal network of microfilaments-Controls biconcave shape and deformability of cell-If denatured red blood cell becomes spherical, Loses flexibility

    -The most abundant peripheral protein

    -Composed of alpha and beta chains

    -Very important in RBC membrane integrity

    +Binds with other peripheral proteins to form the cytoskeletal network of microfilaments

    -Controls biconcave shape and deformability of cell

    -If denatured red blood cell becomes spherical, Loses flexibility

  • What is Ankyrin?

    -Primarily anchors lipid bilayer to membrane skeleton via interaction with spectrin and Band 3

    -Primarily anchors lipid bilayer to membrane skeleton via interaction with spectrin and Band 3

  • What is protein 4.1?

    -May link the cytoskeleton to the membrane by means of its associations with glycophorin-Stabilised interaction of spectrin with actin

    -May link the cytoskeleton to the membrane by means of its associations with glycophorin

    -Stabilised interaction of spectrin with actin

  • What is Actin?

    -Responsible for the contraction and relaxation of the membrane (Strong cohesion between bilayer and membrane skeleton maintains surface area)

    -Responsible for the contraction and relaxation of the membrane (Strong cohesion between bilayer and membrane skeleton maintains surface area)

  • What are carbohydrates?

    -They occur only on the external surface of cell-The carbohydrate groups are attached to proteins and lipids by a process called glycosylation-They may contain 2-60 monosaccharide units, either branched or straight-The carbohydrate gives a cell identity; the distinguishing factor for human blood types

    -They occur only on the external surface of cell

    -The carbohydrate groups are attached to proteins and lipids by a process called glycosylation

    -They may contain 2-60 monosaccharide units, either branched or straight

    -The carbohydrate gives a cell identity; the distinguishing factor for human blood types

  • State ATLEAST 5 different monosaccharides that are found on the red cell membrane

    -Galactose

    -Mannose

    -Fucose

    -N-acetylgalactosamine

    -Glucuronic acid

    -Glucose

    -Sialic acid

    -N-acetylglucosamine

  • What determines are blood group?

    Blood group antigens, which are found on the red cell membrane

  • Statement: The Majority of antigens are carbohydrates. Is this true or false?

    FALSE

    The majority of antigens are proteins; e.g. Rhesus, Duffy.

    Others are carbohydrates; e.g. ABO

    Others are combination of glycolipids and proteins

  • Picture illustrating idea in previous flashcard:

  • What is the primary function of RBC? And how is this achieved?

    -Primary function of RBC is transport of respiratory gases to and from the tissues

    -To achieve this, RBC traverse the microvascular system without mechanical damage and retain a shape which facilitates gaseous exchange

    -The red cell membrane should be extremely tough yet highly flexible

    +Cytoskeletal proteins interaction with the membrane lipid bilayer determines strength and flexibility

  • List 4 characteristics of the RBC and their importance

    1)SHAPE: provides the optimum surface area to volume ratio for respiratory gases exchange

    2)DEFORMABILITY, ELASTICITY: allowing for the passage through micro vessels (capillaries)

    3) Regulates intracellular cation concentration

    4)Acts as the interface between the cell and its environment via membrane surface receptors

  • Statement: Membrane cholesterol exists in free equilibrium with plasma cholesterol.... True or false?

    TRUE

  • An increase in free plasma cholesterol results in an accumulation of what in the RBC membrane?

    Cholesterol

    Cholesterol

  • RBCs with increased cholesterol appear distorted, which results in the formation of..........?

    Acanthocytes

    Acanthocytes

  • An increase in cholesterol and phospholipid is due to what?

    Target cells; due to specifically high SA

  • What are the two possible defects in the RBC membrane?

    1)Hereditary spherocytosis; Instead of RBC being shaped like a disk, the cells are round like a sphere

    2)Hereditary Elliptocytosis; RBCs assume an elliptical shape, rather than the typical round shape

  • What is Hereditary Spherocytosis caused by?

    -Ankyrin deficiency or abnormalities-a or b spectrin deficiency or abnormalities-Band 3 protein abnormalities-Protein 4.2 abnormalities

    -Ankyrin deficiency or abnormalities

    -a or b spectrin deficiency or abnormalities

    -Band 3 protein abnormalities

    -Protein 4.2 abnormalities

  • What is Hereditary Elliptocytosis caused by?

    -a or b spectrin mutation - defective spectrin dimer-a or b spectrin mutation - defective spectrin-ankyrin association-Protein 4.1 deficiency or abnormalities

    -a or b spectrin mutation - defective spectrin dimer

    -a or b spectrin mutation - defective spectrin-ankyrin association

    -Protein 4.1 deficiency or abnormalities

  • Picture demonstrating the various RBC shapes and sizes:

  • State some information about Haemoglobin structure

    -Haemoglobin (Hb) is a globular haemoprotein-haemoproteins are a group of specialized proteins that containHaem as a tightly bound prosthetic group.-The haem is a complex of protoporphyrin IX and ferrousiron (Fe2+).-The protein here is globin: 4 polypeptide subunits-2 α-globin chains-2 β-globin chains

    -Haemoglobin (Hb) is a globular haemoprotein-haemoproteins are a group of specialized proteins that containHaem as a tightly bound prosthetic group.-The haem is a complex of protoporphyrin IX and ferrousiron (Fe2+).-The protein here is globin: 4 polypeptide subunits-2 α-globin chains-2 β-globin chains

  • What is the Adult amounts of haemoglobin in adults (both male and female)?

    Haemoglobin content (ADULT)Female 11.5- 15.5g/dlMale 13.5- 17.5g/dl

  • What does Haemoglobinopathies mean?

    A group of recessively inherited genetic conditions affecting the haemoglobin component of blood

  • Inherited disorders of Hb can be split into 2 categories: what are these categories

    1. Thalassaemias

    2. Sickle Cell Disease

  • What are the two main metabolic pathways?

    -The pentose phosphate pathway

    -The glycolytic pathway

  • What are the two main enzymes associated with these pathways?

    1.Glucose-6-Phosphate Dehydrogenase (G-6-PD)2.Pyruvate Kinase (PK)

  • State some information about the Glycolytic pathway (PK enzyme)

    - Glucose is metabolized and generates two molecules of ATP(energy).- Generates 90- 95% of energy needed by RBC’s- Functions in the maintenance of RBC shape, flexibility and the cation pumps (Na/K pump)

  • Outline the series of reactions in the glycolytic pathway

  • What is a PK deficiency, and what happens during a PK deficiency?

    Pyruvate kinase deficiency is a condition in which red blood cells break down faster than they should.-ATP is depleted-Cells lose large amount of potassium and water, becoming dehydrated and rigid-Causes chronic non-spherocytic haemolytic anaemia

    Pyruvate kinase deficiency is a condition in which red blood cells break down faster than they should.

    -ATP is depleted

    -Cells lose large amount of potassium and water, becoming dehydrated and rigid

    -Causes chronic non-spherocytic haemolytic anaemia

  • State some information about the pentose phosphate pathway

    - The pentose phosphate provides the reducing power,NADPH- NADPH maintains glutathione in the reduced form (GSH)- RBC uses GSH to protect it from oxidative damage;

  • Outline the series of reactions in the pentose phosphate pathway

  • What is another name for the Pentose phosphate pathway?

    Hexose monophosphate shunt

  • What causes a G6DP deficiency?

    G6PD deficiency is inherited

  • What does a G6DP deficiency do?

    -NADPH and GSH generation impaired+Acute intravascular haemolysis on exposure to oxidant stress: oxidativedrugs, fava beans (broad beans) or infections;=dark urine- Hb precipitation – Heinz bodies- G6PD deficiency, most common known enzymopathy, estimated to affect 400 million people worldwide.RBC effected are called bite cells

    -NADPH and GSH generation impaired

    +Acute intravascular haemolysis on exposure to oxidant stress: oxidativedrugs, fava beans (broad beans) or infections;=dark urine- Hb precipitation – Heinz bodies

    - G6PD deficiency, most common known enzymopathy, estimated to affect 400 million people worldwide.

    RBC effected are called bite cells

  • A general summary for this lecture:

    RBC membrane is made of lipids, proteins and carbohydrates.- Glycophorin and spectrin are among the most importantproteins.- Spectrin plays important role in membrane deformability &stability- Biconcave disc shape creates an advantageous surfacearea/volume relationship- Changes to SA/V ratio result in more spherical shape withless redundant surface area, and thus less capacity fordeformability and diminished survival.- Key metabolic pathways required to maintain red cell integrityand deformability.