Lecture 6 Flashcards
(29 cards)
what is the natural shape of an RBC? why is this important?
- biconcave disk
- structure = function
- allows for greater surface area & flexibility
normocytic
normal size;
volume: 80-96 fL
normochromic
normal colour
RBC colour is dictated by amount of Hgb present
(~1/3 central pallor)
T/F if you see less central pallor, it means there is less Hgb
false
what are the 3 parts of the RBC
- membrane
- internal stroma (support)
- cell contents (Hgb is main)
what are the pros and cons of an RBC not having a nucleus?
pro: flexibility
con: unable to repair itself
what happens at the end of an RBCs life span?
removed by macrophages; primarily in spleen (erythrophagocytosis)
what causes sickle cells?
- abnormal Hgb forms strands and causes sickle shape
- loses deformability and clog vessels
which of the following is false regarding the RBC membrane phospholipid bilayer?
a) permeable
b) composed of protiens, lipids and carbohydrates
c) peripheral is a fluid mosaic model
d) has integral and peripheral proteins
a) permeable, it is actually semipermeable so it can control what moves in and out of cell
what is true regarding the lipid layer of RBC
a) consists of 2 groups of phospholipids symmetrically arranged
b) choline phospholipids are primarily internal
c) amino phospholipids are primarily external
d) can release and protrude an internal phospholipid on outside to signal spleen to destroy it
d)
choline phospholipids
- primarily external
- phosphatidylcholine & sphingomyelin
amino phospholipids
- primarily internal
- phosphatidylethanolamine
- phosphatidylserine (only neg charge, only internal)
- phosphatidylinositol (internal and external)
glycoproteins
- primarily external
- contribute to net neg charge (protection against bacteria)
- associated w/ blood group Ag
cholesterol
- primarily internal
- inner & outer tho
- contributes to mem. strength
- 1:1 ratio w/ phospholipids
which of the following is not part of the lipid layer?
a) choline phospholipid
b) amino phospholipid
c) glycoprotein
d) cholesterol
c) glycoprotein (glycolipids)
cholesterol is regulated by
membrane enzymes
what happens when there is an increase in plasma cholesterol? what would cause this increase?
- RBC membrane gains strength but loses deformability
- intake of fatty meal (lipemia) may alter membrane and change RBC morphology
what can you see on an RBC that may indicate extra lipid?
target cells
what are 2 proteins found in the RBC membrane
integral –> transmembrane
peripheral –> cytoskeleton
where are integral proteins found and what is their function?
- transmem.
- span lipid bilayer, exposed on surface, carry RBC Ag
function:
- maintain RBC osmotic balance (albumin) (affects deformability + viscocity)
- maintain adhesion sites to prevent RBC from sticking to each other + vessel walls
where are peripheral proteins found and what is their function?
- cytoskeleton (internal)
- surface of membrane
function:
- integrity of RBC
- formation of lattice network
- e.g. spectrin, actin, ankyrin
what happens if you are missing any peripheral proteins?
- scaffolding is not maintained & loses deformability
the RBC membrane is selectively permable to:
a) bicarb (HCO3)
b) Cl-
c) Na+
d) K+
e) Ca2+
f) more than one of these
f) bicarb and Cl-
the RBC membrane is selectively impermeable to:
a) bicarb (HCO3)
b) Cl-
c) Na+
d) K+
e) Ca2+
f) more than one of these
f) Na, K and Ca
