The assignment of mitochondria to daughter cells at mitosis also appears to be random. Indeed, it was the observation of somatic variation in plants that first suggested the existence

of genes that could be lost from one of the daughter cells because they were not inherited according to Mendel's laws.

TLS Online TPP Program

#Id: 5414

#Unit 7. System Physiology – Animal

Astrocytes, which are found throughout the brain, are of two subtypes:

Fibrous astrocytes

Protoplasmic astrocytes

TLS Online TPP Program

#Id: 5415

#Unit 7. System Physiology – Animal

Fibrous astrocytes, contain many intermediate filaments are found primarily in white matter.Protoplasmic astrocytes are found in gray matter and have a granular cytoplasm.

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#Id: 5416

#Unit 7. System Physiology – Animal

Both Astrocytes

send processes to blood vessels, where they induce capillaries to form the tight junctions making up the blood–brain barrier send processes that envelop synapses and the surface of nerve cells.

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#Id: 5417

#Unit 7. System Physiology – Animal

Protoplasmic astrocytes produce substances that are tropic to neurons, & they help maintain the appropriate concentration of ions & neurotransmitters by taking up K+ & neurotransmitters glutamate & γ-aminobutyrate (GABA)

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#Id: 5418

#Unit 7. System Physiology – Animal

Ependymal cells are ciliated-epithelial glial cells that develop from radial glia along the surface of the ventricles of the brain and the spinal canal & play a critical role in cerebrospinal fluid homeostasis, brain metabolism, and the clearance of waste from the brain.

TLS Online TPP Program

#Id: 5419

#Unit 7. System Physiology – Animal

Neurons generally have four important zones:

A dendritic zone, where multiple local potential changes generated by synaptic connections are integrated. a site where propagated action potentials are generated. an axonal process that transmits propagated impulses to the nerve endings the nerve endings, where action potentials cause the release of synaptic transmitters.