First run Flashcards
How do complex cells differ from unicellar unit and sponges
In complex cell structures, cells can communicate so that outside stimuli by one cell can Result movement or Secretory activity (expulsion of biosynthetic product ) from other cells
What is myelin sheath and why does it exist
A lipid rich material composed of tightly packed
membranous layer (fusion of fibers ) that
ensheaths the axons
it exisit to insulate the axons from the enviroment
in order to increae the rate that electric impulses pass
through it , it does not cosisit of a single long sheath
but in several “sections” with gaps that are called the
nodes of raniver
What is the Central nervous system
The brain and the spinal cord it is protected by the cranium (the part of the skull
That protects the brain) and the vertebral column
What are the two types of neurites in higher animals and how do they differ
Dendrites – conduct signals toward the cell body.
Axons – conduct signals away from the cell body.
what are the two activities of a neuron cell (how they communicate)
- Conduction of signal from one part of the cell to another part.
- Synaptic transmission - communication between adjacent cells
What is the gray matter
Regions in the CNS where the cell body of neurons are
located , it also containts Neuropil (dendriets and unmylenatied axons)
What are 3 main components of the nerve cell and what do they do
- Neurites = Cytoplasmic processes (long branch like physical projections from the cell body ) that conduct and transmit signals, they end close to adjacent cells
- Synaptic terminals = the ends of the neurites
- Synapses = the cell to cell contacts of the neurites
What are the functions of cells to what they respond and how they react? unicellar and sponge
(simplest muiltcellar animals)
Cells respond to physical or chemical stimuli from the environment
The react with movements or expulsion of biosynthetic products from the cell
what happens when an impulse arrives at the synaptic terminals?
a synaptic transmission occurs, usually it is accompanied by a release of a chemicalfrom the first neuron that evokes response in the post synaptic cell.
The first step is opening of calcium ion channels in the membrane of the axon, allowing calcium ions to flow inward across the membrane. The resulting increase in intracellular calcium concentration causes synaptic vesicles (tiny containers enclosed by a lipid membrane) filled with a neurotransmitter chemical to fuse with the axon’s membrane and empty their contents into the extracellular space.
Some neurons transfer electrical charges from one to other (electrically coupled)
What are neurons (at the most basic level)
Neurons also know as nerve cells are special cells that exist to communicate information from one
part of an animal body to another
What are neurosecretory cells
A special type of neurons that release a chemical into the blood and trigger an event at distant
parts of the body, they are related to the endocrine gland cells.
What are ganglia
Small lumps where the neuron bodies are located in the peripheral nervous system
What are nerves
Bundles of axons that connect the CNS with the rest of the body
What is white matter
Regions of the CNS that contain axons but not cell bodies
What is a nucleus (not cell nucleus)
A compact aggregation of gray matter which is where the cell body of neurons are located
