Human Anatomy Introduction to Cells

• A cell is made up of the cell membrane, the cytoplasm, cytosol, cytoplasmic inclusions, and organelles such as lysosomes.
• The cell membrane, also known as the plasma membrane, is a biological membrane that separates the interior of the cell from the outside environment.
• The cell membrane has a phospholipid bilayer with proteins, lipids, carbohydrates, and other molecules in it.
• Adrenoleukodystrophy is a X-linked recessive disorder of beta oxidation due to mutation of ABCD1 gene, resulting in VLCFA buildup in adrenal glands, white matter of brain, and testes.
• Adrenoleukodystrophy is a progressive disease that can lead to adrenal gland crisis, progressive loss of neurological function, and death.
• Glycocalyx is a covering made of glycoprotein & glycolipid that surrounds the cell membrane of the epithelial cell.
• The glycocalyx acts as an interface between the extracellular matrix and cellular membrane.
• The various functions of glycocalyx of a cell include cell recognition, cell-cell communication, cell adhesion, protection, and permeability barrier.
• In the intestinal tract, on the apical side of the microvilli, a 0.3 μm thick mesh or glycocalyx can be found.
• Glycocalyces protrude outside the apical portion in the intestine on the intestinal luminal surface.
• The intestinal glycocalyx, made up of acidic mucopolysaccharides and glycoproteins, helps in the absorption of nutrients and release of digestive enzymes for the breakdown of the food.
• The negative end of the microtubule is towards the nucleus of the neuronal cell and the positive end is oriented towards the periphery of the neuronal cell.
• The microtubule has a negative end and a positive end.
• Cilia is a Basal body (9 triplets) + Axoneme (9+2 pattern).
• Microtubules are involved in axonal transport, acts as a railroad track to move things up and down the neuronal cell.
• Cell Junction: Hemi-Desmosome which help anchor a cell to the underlying basement membrane (extra cellular matrix)
• Centrosome gives of mitotic spindles.
• Antegrade transport involves Kinesin from –ve end to +ve end.
• Microtubules are thin hollow tubes made of alpha tubulin & beta tubulin monomer units.
• Diseases arising from mutations in IF genes, example is Dilated Cardiomyopathy (DCM), which is a mutation in the DES gene.
• Cell Division: Centrosome has two centrioles.
• Basal body is also called as Centriole.
• Flagella is a Basal body (9 triplets) + Axoneme (9+2 pattern).
• Kinetochore is the middle of Centromere.
• Centromere is the middle of the chromosome.
• Retrograde transport involves Dynein, axonal transport from axonal terminal towards head/body of the neuronal cell.
• The functions of a mitochondrion include the release of energy for cell to perform work (osmotic, mechanical, electrical or chemical) via Citric Acid (Krebs) Cycle and via the electron transport chain.
• There are two types of ER: rough ER (because it has ribosomes on the surfaces) and smooth ER.
• F1 particles comprise about 15% of the total inner membrane protein.
• The functions of the smooth Endoplasmic Reticulum (sER) include lipid synthesis, steroid synthesis, and breakdown of endogenous and exogenous compounds.
• The ER is a system where the continuous membrane forms flattened sacs.
• Mitochondria are also involved in heat production, storage of cations (e.g Calcium & Magnesium), regulate cell proliferation and programmed cell death, and contain the mitochondrial genome which is transmitted from mothers to offsprings.
• Organs rich in RER are the Exocrine Pancreas which produce a lot of Digestive enzymes like Lipase, Amylase, Goblet Cells in Respiratory Tract & Colon (GIT) to produce mucinous proteins, Plasma Cells which produce a lot of antibodies, and Nissil body (RER) in Neurons which produce a lot of Neuro-transmitters.
• In mitochondria, F1 particles function in synthesis of ATP from ADP + Pi.
• The functions of the rough Endoplasmic Reticulum (rER) include protein synthesis, protein modification, protein folding, protein quality control, and protein sorting.
• The cell membrane maintains the structure and integrity of a cell, separates the interior of the cell from the outside environment, allows for the diffusion of some substances in and out of the cell, actively controls the passage of other substances into and out of the cell, controls the signaling from the outside to the inside of the cell, and carries identifying markers/signals.
• Cholesterol acts as a buffer to help maintain fluidity in the cell membrane.
• The cell membrane is semi-permeable (selectively permeable).
• Endocytosis is the process of taking in matter by a living cell by invagination of its membrane to form a vacuole.
• Exocytosis is the last step of the secretory pathway and it involves the fusion of vesicles with the plasma membrane.