📚 NEET MDS Lecture Notes
Lysosomal (lipid) storage diseases
General PathologyLysosomal (lipid) storage diseases
- Genetic transmission: autosomal recessive.
- This group of diseases is characterized by a deficiency of a particular lysosomal enzyme. This results in an accumulation of the metabolite, which would have otherwise been degraded by the presence of normal levels of this specific enzyme.
Diseases include:
Gaucher’s disease
(1) Deficient enzyme: glucocerebrosidase.
(2) Metabolite that accumulates: glucocerebroside.
(3) Important cells affected: macrophages.
Tay-Sachs disease
(1) Deficient enzyme: hexosaminidase A.
(2) Metabolite that accumulates: GM2 ganglioside.
(3) Important cells affected: neurons.
(4) Symptoms include motor and mental deterioration, blindness, and dementia.
(5) Common in the Ashkenazi Jews.
Niemann-Pick disease
(1) Deficient enzyme: sphingomyelinase.
(2) Metabolite that accumulates: sphingomyelin.
(3) Important cells affected: neurons.
Typical Concentration Gradients and Membrane Potentials in Excitable Cells
PhysiologyTypical Concentration Gradients and Membrane Potentials in Excitable Cells
The Na Pump is Particularly Important in the Kidney and Brain
- All cells have Na pumps in their membranes, but some cells have more than others
- Over-all Na pump activity may account for a third of your resting energy expenditure!
- In the kidney the Na pump activity is very high because it is used to regulate body salt and water concentrations
- Kidneys use enormous amounts of energy: 0.5% of body weight, but use 7% of the oxygen supply
- Pump activity is also high in the brain because Na and K gradients are essential for nerves
- The brain is another high energy organ; it is 2% of body weight, but uses 18% of the oxygen supply
In the Resting State Potassium Controls the Membrane Potential of Most Cells
- Resting cells have more open K channels than other types
- More K+ passes through membrane than other ions- therefore K+ controls the potential
- Blood K+ must be closely controlled because small changes will produce large changes in the membrane potentials of cells
- Raising K will make the membrane potential less negative (depolarization)
- High blood K+ can cause the heart to stop beating (it goes into permanent contraction)
During an Action Potential Na Channels Open, and Na Controls the Membrane Potential
- Whichever ion has the most open channels controls the membrane potential
- Excitable cells have Na channels that open when stimulated
- When large numbers of these channels open Na controls the membrane potential
PSEUDOEPHEDRINE
PharmacologyPSEUDOEPHEDRINE
Pseudoephedrine appears to have less pressor activity and weaker central nervous system effects than ephedrine. It has agonist activity at both β1 and β2 adrenoceptors, leading to increased cardiac output and relaxation of bronchial smooth muscle.
Pseudoephedrine is rapidly absorbed throughout the body. It is eliminated largely unchanged in urine by N-demethylation.
It is indicated in symptomatic relief from stuffed nose, respiratory tract congestion, bronchospasm associated with asthma, bronchitis and other similar disorders.
Cell, or Plasma, membrane
PhysiologyCell, or Plasma, membrane
- Structure - 2 primary building blocks include
protein (about 60% of the membrane) and lipid, or
fat (about 40% of the membrane).
The primary lipid is called phospholipids, and molecules of phospholipid form a 'phospholipid bilayer' (two layers of phospholipid molecules). This bilayer forms because the two 'ends' of phospholipid molecules have very different characteristics: one end is polar (or hydrophilic) and one (the hydrocarbon tails below) is non-polar (or hydrophobic):
- Functions include:
- supporting and retaining the cytoplasm
- being a selective barrier .
- transport
- communication (via receptors)