Bio 224 theme 5
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Central nervous system
Brain and spinal cord in vertebrates
Peripheral nervous system
(PNS) All neurons and projections of their plasma membranes that are outside of the CNS
- the major component of the CNS, consisting of:
- –Neuronal cell bodies, dendrites and axons;
- –Glial cells;
- mostly contains myelinated axon tracts
- –The color difference arises mainly from the whiteness of myelin.
- Generate, send and receive information
- through electrical and
- chemical signals;
- to and from other neurons or other cells throughout the body
What animals don't have neurons?
What cells can be excitable
neurons, muscle cells, and endocrine cells, as well as in some plant cells
What is the voltage for:
What is the resting potential?
What effect do action potentials have on muscle cells?
B-cells in pancreas?
- -an action potential is the first step in the chain of events leading to a contraction
- -release of insulin
What makes up dendrites and axons?
what part of a neuron contains the nucleus and organelles?
the cell body or soma
Branched projections of a neuron that conduct the electrochemical stimulation received from other neural cells.
- -Long, slender projection of neurons
- -Conducts electrical impulses away from the soma;-rich in voltage-gated ion channels
- -place of transmission of neurotransmitters/electrical impulse, from axon to dendrite
- -full of neurotransmitter vesicles
- -Dendrite receptor is loaded with ligand gated ion channels
Glial Cells or Neuroglia
- •Non nervous cells of the NS
- –commonly known as the glue of the NS
What are the ratios of Glial cells to neurons in the brain
- roughly 1:1
- in cerebellum 3:2
What are the six types of Glial cells
- 3.Ependymal cells
- 5.Satellite cells
- 6.Schwann cells
–star-shaped glial cells–provision of nutrients–maintenance of extracellular ion balance; –repair and scarring process of the brain and spinal cord; and–biochemical support of endothelial cells
The Blood brain Barrier (BBB)
-effect on different molecules
- •A separation between the circulating blood and the brain extracellular fluid;
- •Consist of tight junctions around the capillaries that do not exist in normal circulation;
- –Restrict the diffusion of microscopic objects, e.g.•bacteria and large or hydrophilic molecules into CSF;
- •while allowing the diffusion of small hydrophobic molecules (O2, CO2, hormones).
- –Actively transport metabolic products such as glucose
- •The principal glia cells of the PNS
- -Wrap around axons of motor and sensory neurons to form the myelin sheath
- •;An electrically inulating material that forms a layer around axons
- •Essential for the proper functioning of the nervous system;
- •Composed of:
- – ~ 80% lipids, primarily the glycolipids galactocerebroside
- –~20% protein
- •myelin basic protein (MBP),
- •myelin oligodendrocyte glycoprotein (MOG), •proteolipid protein (PLP).
Schwann cells myelinate the _NS
Oligodendrocytes myelinate the _NS
Schwann cells myelinate the PNS Oligodendrocytes myelinate the CNS
Three Main Types of Neurons
- •Interneurons or Association Neurons
- •Motor neurons
- •Sensory neurons
Interneurons or Association Neurons
- –Form interconnections between other neurons in the CNS;
- –Tend to have many dendrites;
- –Axons are typically short and highly branched allowing them to form complex connections with other cells
–Efferent: send signals away from CNS to elicit response
- –Afferents: detect information from the outside world or internal body conditions & transmit to the CNS;
- –Usually a large axon that bypasses the cell body and goes directly to the CNS
- •The stimulus from sensory neurons is sent to the CNS, but there is little or no interpretation of the signal;
- –Few interneurons are involved
- •The signal is then transmitted to motor neurons, which elicit a response, such as a knee jerk
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