HISTOLOGY REVIEW

HISTOLOGY REVIEW
The cell and its components
 Main components of the cell
 The cell membrane
 The cytoplasm
 The nucleus
 Difference btwn cytoplasm and cytosol
 Cytosol is cytoplasm minus the organelles- it’s the fluid part of the cytoplasm
 Cytoplasm
 Organelles
 Matrix called cytosol
 Forms framework of the cell referred to as cytoskeleton
 Has structures know as inclusions
 Difference btwn organelles and inclusions
 Organelles permanent structures in a cell Inclusions could be temporary, eg lipid granules
 Organelles are universal cell types while inclusions are found in specific cells eg melanin will be
found in melanocytes
 Organelles have their origin from the cell, while the inclusion are usually derived from the
external environment
 Functions and distribution of the following organelles
 Mitochondria-
 energy production produced by oxidation of fatty acids, called oxidation phosphorylation
 Has its own DNA
 Regulate apoptosis- whether a cell dies or not
 Responsible sequestration of potassium ie for removing potassium from blood to cell-
important in preventing hypoglycemia*
 Found in highly active cells
 RER
 Has ribosomes to provide sites for protein synthesis
 Glycosylation of proteins
 Provides sites for storage of calcium
 Assist in transport of the synthesized proteins
 Found in organs producing enzymes eg, protein synthesizing cells
 SER
 Synthesis of steroids or lipids eg in adrenal cortex which secretes steroids like aldosterone,
also testis, oogonia
 Detoxification
 Stores calcium
 Synthesis of phospholipids

,  Modified to form sarcoplasmic reticulum which is found in skeletal muscle and responsible
for muscle contraction
 Golgi apparatus
 Goes hand in hand with RER
 Packaging and transportation of proteins
 Forms secretory vesicles
 Involved in formation of lysosomes
 Ribosomes are synthesized inside the nucleolus then they will go into the cytoplasm cause
this is where protein synthesis occurs then the golgi apparatus then transports them
outside the cell in secretory vesicles where they are required
 Lysosomes
 Intracellular digestion of foreign materials
 Destroys cellular debri- the worn out part of the cell
 Lack of lysomes makes you predominant to bacterial infections
 Autosomes- lysosomes destroy intracellular material
 Phagosomes- destroy extracellular material
 Found in cells highly active in phagocystic processes
 Brain-Microglial cells
 Lungs-Pulmonary alveolar microphages
 Liver- kupher cells
 Bone- osteoclasts
 Skin-langerhans cells
 Connective tissue-microphages
 Blood-monocytes
 Lack of em(lysosomes) results to chediak higashi syndrome- defective phagocytosis
 Results to recurrent bacterial syndrome
 Peroxisomes
 Similar to lysosomes
 Double membrane but lysosomes single membrane
 Detoxification of lipids
 Mainly found in hepatocytes
 Disorderes affecting cell organelles
 Peroxisomes-zelweger’s defective activity of peroxisomes
 Lysosomes- lysosomal storage disease eg gaucheur’s disease
 Mitochondria- mitochondrial myopathys
 Structural components and functions of cell membrane
 has a phospholipid bilayer-responsible for structural integrity of cell membrane- cell membrane
framework
 with protein layer in btwn- act as receptors, ion channels, pumps cause it provides sites for drug
function
 fluid in the cell membrane-responsible for the dynamism of the cel membrane ie referred to
fluid mosaic(complex of phospholipids and proteins) model