Clinical Relevance of Cell Membranes and Transport

Question 1

What are the components that makeup Glycerophospholipids?

Answer 1

Glycerol backbone
2 fatty acid chains
Phosphate and alcohol

Question 2

What are the components that makeup Sphingolipids? (Note that there are two types of Sphingolipids)

Answer 2

Sphingosine backbone attached to:
1 fatty acid chain
Phosphate and choline

Sphingosine backbone attached to:
1 fatty acid chain
Phosphate and mono/oligosaccharide

Question 3

What causes Niemann Pick Disease?

Answer 3

Caused by a deficiency in the activity of the enzyme Acid Sphingomyelinase (A-SMase), which is an enzyme that breaksdown sphingomyelin (SM)

When this enzyme does not work it leads to an accumulation in SM in lysosomes of the liver, spleen, CNS, and bone marrow

Question 4

What 3 diagnostic factors do patients that suffer from Niemann Pick Disease have?

Answer 4

Hepatomegaly (enlarged liver)
Splenomegaly
Cherry red spot in the eye (Hallmark sign)

Question 5

What is the fatality rate for patients suffering from Niemann Pick Disease?

Answer 5

85% die by 18 months

Question 6

What are the components that makeup sphingomyeline?

Answer 6

Sphingosine backbone attached to:
1 hydrocarbon chain
1 Fatty acid
Phosphate attached to a choline (phosphorylcholine)

Question 7

When sphingomyelinase breaks down sphingomyelin, what are the products?

Answer 7

Ceramide and Phosphorylcholine

Question 8

How do cells know that it is time to kill other cells that are undergoing apoptosis?

Answer 8

Phosphatidylserine is usually found on the inner leaflet, but when a cell is undergoing apoptosis, the cell opens and exposes phosphatidylserine to the outer leaflet

Question 9

How do we physically see apoptotic cells?

Answer 9

Researchers are able to mix Propridium Iodide (PI) with the cell and if the cell allows PI to enter the cell, the cell will light up red instead of green

Question 10

What are the chemicals that make up the ABO blood group O? (Note that this is the backbone for every other blood antigen group)

Answer 10

RBC-Gal- GlcNAc-Gal-Fuc

Question 11

What are the chemicals that make up the ABO blood group A?

Answer 11

RBC-Gal- GlcNAc-Gal-Fuc—- GalNAc

Question 12

What are the chemicals that make up the ABO blood group B?

Answer 12

RBC-Gal- GlcNAc-Gal-Fuc—– Gal

Question 13

What are the chemicals that make up the ABO blood group AB?

Answer 13

RBC-Gal- GlcNAc-Gal-Fuc—- GalNAc

AND

RBC-Gal- GlcNAc-Gal-Fuc—- Gal

Question 14

Which one is the universal donor, Type O or Type AB. Why?

Answer 14

Type O is the universal do not because the rbcs do not have any group antigens. But they can only receive from O because they have antibodies to types A and B

Question 15

Which one is the universal acceptor, Type O or Type AB. Why?

Answer 15

Type AB is the universal acceptor because the plasma does not contain any antibodies to A or B

Question 16

What do Rh+ individuals express that Rh- individuals do not? What disease is associated with this in terms of pregnancies?

Answer 16

Rh+ individuals express D antigen

Erythroblastosis fetalis is a disease where there is an incompatibility between the blood of the mother and the fetus.

When the mom is Th- and the fetus is Rh+, the mom produces antibodies during pregnancy. These cross the placenta and attack the fetus. Risk increases with each subsequent pregnancy.

Question 17

What are the 3 factors that control membrane fluidity?

Answer 17

Temperature
Lipid Composition
Cholesterol

Question 18

How does cholesterol influence membrane fluidity?

Answer 18

If the membrane is rigid, cholesterol increases fluidity
-This is because if the membrane is highly saturated it is considered rigid, and the cholesterol will push open the membrane and prevent close packing of the lipids. This increases the fluid

If the membrane is fluid, cholesterol decreases fluidity
-This is because if the membrane is fluid do to high amounts of unsaturated fatty acids, the cholesterol stabilizes the fluidity by filling in the gaps

Question 19

What causes Spur Cell Anemia to occur?

Answer 19

Alcohol liver cirrhosis causes chronic liver dysfunction, which imparies cholesterol metabolism by the liver, resulting in excess free cholesterol.

Elevated levels of cholesterol remain bound to the rbc membrane. This decreases the fluidity and flexibility of the membrane, causing thorny projections on the rbcs called acanthocytes. This causes hemolysis (breaking of rbcs) as they pass through capillaries of the spleen

Question 20

How do you treat spur cells/acanthocytes?

Answer 20

Liver transplant

Question 21

What causes Cystinuria? What does this cause?

Answer 21

Defects in the amino acid transport responsible for the uptake of dimeric amino acid Cystine

This causes Cystine crystals or kidney stones

Question 22

What causes Hartnup Disease? What is the one amino acid that is particularly problematic if there is a defect?

Answer 22

Defects in the transport of non-polar or neutral amino acids such as alanine, valine, threonine, leucine, or tryptophan.

Tryptophan serves as the precursor for biomolecules such as serotonin, melatonin, and niacin (precursor of NAD+)

Question 23

What are the clinical findings for patients that suffer from Hartnup disease?

Answer 23

Cerebellar ataxia
Photodermatitis
Photosensitivity

Question 24

What is Hartnup disease AKA? What triggers this?

Answer 24

Pellagra-like dermatosis

Triggered by sunlight, fever, drugs, or stress

Question 25

What are the 2 cardiotonic drugs? What do these drugs do?

Answer 25

Cardiac glycosides like ouabain and digitoxin act as drugs that induce contraction of the heart.

Question 26

How does cardiac glycosides such as oubain and digitoxin cause cardiac constriction?

Answer 26

These drugs inhibit the Na+/K+ ATPase in cardiac monocytes, which leads to an incraese in intracellular Na+

An increase in intracellular Na+ impairs the Na+/Ca2+ exchanger, which leads to an increase in Ca2+ within the sarcoplasmic reticulum. An increase in calcium within the heart cells increases the force of contractions.

Question 27

Patients suffering from what 3 dzs can utilize cardiotonic drugs?

Answer 27

CHF
Atrial fibrillation
Dysrhythmias

Question 28

What is defective in patients suffering from cystic fibrosis? What does this cause?

Answer 28

Chloride ion transport, specifically the transmembrane conductance regulator (CFTR) gene. This causes chloride ions to not be able to leave the epithelial airway cells. This causes Na+ and water to enter the cell at a higher rate to compensate, which causes mucus to buildup around the airway cells and thicken.