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The brainstem is very small, making up around only 2.6 percent of the brain's total weight. [3] It has the critical roles of regulating heart and respiratory function, helping to control heart rate and breathing rate. [4] It also provides the main motor and sensory nerve supply to the face and neck via the cranial nerves.
The pedunculopontine nucleus (PPN) or pedunculopontine tegmental nucleus (PPT or PPTg) is a collection of neurons located in the upper pons in the brainstem. [1] [2] It is involved in voluntary movements, [3] arousal, and provides sensory feedback to the cerebral cortex and one of the main components of the ascending reticular activating system.
Squamous Squamous cells have the appearance of thin, flat plates that can look polygonal when viewed from above. [5] Their name comes from squāma, Latin for "scale" – as on fish or snake skin. The cells fit closely together in tissues, providing a smooth, low-friction surface over which fluids can move easily.
There are four basic types of animal tissues: muscle tissue, nervous tissue, connective tissue, and epithelial tissue. [5] [9] All animal tissues are considered to be subtypes of these four principal tissue types (for example, blood is classified as connective tissue, since the blood cells are suspended in an extracellular matrix, the plasma). [9]
The cells of the brain include neurons and supportive glial cells. There are more than 86 billion neurons in the brain, and a more or less equal number of other cells. Brain activity is made possible by the interconnections of neurons and their release of neurotransmitters in response to nerve impulses.
Although this epithelium is referred to as squamous, many cells within the layers may not be flattened; this is due to the convention of naming epithelia according to the cell type at the surface. In the deeper layers, the cells may be columnar or cuboidal. [1] There are no intercellular spaces.
As the main stem cell population for the tissue they are found in, therefore responding to stimuli to maintain homeostasis within that tissue; While all basal cells, regardless of location, function similar in regards to anchoring the epithelium, the specific function and mechanisms of basal cells as stem cells varies by location.
Endogenous regeneration in the brain is the ability of cells to engage in the repair and regeneration process. While the brain has a limited capacity for regeneration, endogenous neural stem cells, as well as numerous pro-regenerative molecules, can participate in replacing and repairing damaged or diseased neurons and glial cells.