Neurons, Synapses, and Signaling

1. Neurons, Synapses, and Signaling Trey Carnegie

2. Neurons • Neuron- An electrically excited cell that processes and transmits information through electrical and chemical signals.

3. Nervous Systems • Central • Brain, spinal cord, and is protected by bone. • Processing info relating to sensory and imagery • Peripheral • Nerves and ganglia • Connects to limbs and organs • Relates to motor movement

4. 3 types of neurons • Sensory neurons- Convert various external stimuli from the outside environment. • Interneuron- Transmits impulses between other neurons. • Motor neurons- Impulses needed to stimulate muscles.

5. EGAM • Effector cells- Cell that receives impulses from neurons • Glial Cells-Insulates, support, and nourishes neighboring neurons. • Astrocytes- Known as astroglia, are star-shaped glial cells in the brain and spinal cord. • Myelin- Insulating material that forms around nerve cells in a process called myelination.

6. Blood Brain Barrier • Protects the neural tissue from variations in blood composition and toxins. It also keeps blood out of the brain.

7. Ion Channels • Stretch-ion channel which the pores in response to mechanical deformation of a neuron’s plasma membrane. • Ligand- ion channel where the protein containing a pore that opens or closes as it changes shape in response to signaling molecule(ligand) • Voltage-ion channel that opens and closes in response to changes in membrane potential

8. Potentials • Membrane potential-Membrane potential is the difference in electric potential between the interior and the exterior of a biological cell. • Resting potential-The relatively static membrane potential of quiescent cells is called the resting membrane potential, as opposed to the specific dynamic electrochemical phenomena called action potential and graded membrane potential.

9. Polarization and Thresholds • Hyperpolarization- change in all membrane’s potential- inside is more neg. than outside • Depolarization- change in cell membrane’s potential- inside is less neg. than outside • Threshold- the potential that an excitable cell membrane must reach for action potential to be initiated

10. Graded Potential • Graded potential-in a neuron, a shift in the membrane potential that has an amplitude proportional to signal strength

11. Action potential • Action potential- an electrical signal that travels along the membrane • A larger axon that is a long extension of a neuron that carries impulses away from the cell body • Myelination- fatty layer of myelin accumulates on nerve cells. Slows down action potential • Salutary conduction- Propagation of action potential along mylenated from one node of Ranvier to the next increasing velocity.

12. Generation of action potential

13. Synaptic Cleft • The space between neurons at a nerve synapses across which a nerve impulses transmitted by a neurotransmitter. • Neurotransmitter- endogenous chemicals that transmit signals across a synapse from one neuron to another 'target' neuron

14. Node of Ranvier • Node of Ranvier- gap occurring at regular intervals between segments of myelin sheath along a nerve axon