Random Facts

Embryology

Neural tube - CNS cells, skeletal motor neurons and axons of preganglionic autonomic neurons; neuroglia: oligodendroglia, astrocytes, ependymal cells.

Neural crest cells - sensory neurons, postganglionic autonomic neurons, Cromaffin cells in adrenal medulla; neuroglia: Scwann cells.

Random Facts

• The dystrophin gene is one of the largest known genes. Dystrophin - a large protein which connects the thin actin filaments to the transmembrane protein beeta-dystroglycan in the sarcolemma.

Duchenne's muscular dystrophy (mutations of the dystrohin gene cause the dystrophin be absent from the muscles.

Becker's muscular dystrophy - milder form. Dystrophin is present, but altered or reduced in amount.

Overview

I've finished reviewing cell biology at last - organelles, cell's transport and communication systems. It was quite an interesting subject, I even felt somehow thrilled. I did it rather thoroughly, using different sources. Reading the experience of other's, using too many recources is discouraged, but I just can't do otherwise, I need different approaces to begin to understand the topic fully. I also guess, as I don't feel the pressure of exam, I can enjoy the process of learning more - it's just for myself.
Right now I've started neurophyiology.

Random Facts.

• Active transopr of Na- and K-ions (Na-K-ATPase) is one of the major energy using process in the body. Thus it accounts for a large part of the basal metabolism. On average, it accounts 24% of energy utilized by cells, and in neurons it accounts 70%.

• About 50% of all known drugs work through G-protein-linked receptors.

• Actin is the most abundant protein in the cells. (At times up to 15% of all proteins of a cell). A structural component of microfilaments (thin filaments).

Good online sites

Blue Histology: http://www.lab.anhb.uwa.edu.au/mb140/
Cell Biology (Dr. Gwen V. Childs): http://www.cytochemistry.net/Cell-biology/
Ed's Basic Histology Gallery: http://www.pathguy.com/histo/000.htm
Histology Learning System (Common Confusions): http://www.bu.edu/histology/m/append04.htm
Histology at SIU SOM: http://www.siumed.edu/~dking2/index.htm
Histology Tutorial: http://medinfo.ufl.edu/year1/histo/
Üldine histoloogia: http://raud.ut.ee/~rraid/index/Uldine%20histoloogia/
NCBI Bookshelf: http://www.ncbi.nlm.nih.gov/sites/entrez?db=Books

What have I been doing.

I've gone through cell cytoplasm, epithelium and connective tissue. Made good notes on paper on nucleus, haven't have time to update notes here.
I also found some good histology and cell biology sites online which I will list next time.

2. Cell nucleus

Components:

1. nucleus membrane (envelope)
   
2. nucleolus


3. chromatine

Most of the cells have 1 round-shaped, loosely-packed nucleus.

Variations:

• relatively small nucleus with tightly backed contents (e.g. cells lining the blood spaces (sinusoids) of the liver (you can't see nucleolus in these nuclei);


• extraordinarily large nucleus (megakaryocytes);


• nucleus of distinctive shape (deeply segmented nucleus of neutrophils);


• binucleated (occasionally some hepatocytes and muscle cells of the heart);


• multinucleated (osteoclasts and sceletal muscle cells);


• without nucleus (erythrocytes, platelets).

Nuclear membrane is composed of 2 parallel unit membranes that fuse with each other at certain regions to form perforations knows as nuclear pores. It can be seen in EM.

• perinuclear cisterna (a 10 - to 30-nm space between two membranes);
  
• inner nuclear membrane (about 6 nm thick, faces the nuclear contact). It's in the close contact with the nuclear lamina which is made up of three polypeptides, called lamins (lamins A, B and C). It's a meshwork of intermediate filaments, 80 to 100 nm thick. Peripheral chromatin adheres to the inner aspectof the nuclear lamina. Certain integral proteins of the inner nuclear membrane act either directly or via other nuclear matrix proteins as contact sites for the nuclear RNAs and chromosomes.
  
• outer nuclear membrane (about 6 nm thick, is studded with ribosomes and faces the cytoplasm). It's continous with rough endoplasmatic reticulum. Its cytoplasmatic surface is surrounded by a thin, loose meswork of the intermediate filaments, vimentin. Its cytoplasmatic surface usually possesses ribosomes, actively synthesizing transmembrane proteins that are destined for the outer or inner nuclear membrane.
  
• nuclear pores (there are 20 - 3000 in one nucleus). It's surrounded by nonmembranous structures embedded in its rim - nuclear polar complex (NPC). It guards selectively passage through the pore.

Nuclear pore complex is composed of nuclear pore and its associated glycoproteins.

- cytoplasmic ring

- middle ring

- nucleoplasmic ring