Chapter 3 Part 1 Flashcards
Neurons:
Specialized cells that are the basic building blocks of the nervous system.
Dendrites:
They emerge from the cell body in branchlike fibres and are the receiving unites that collect messages and send them on to the cell body
Axon:
An extension from one side of the neuron cell body that conducts nerve impulses to other neurons, muscles, or glands.
Glial Cells:
Surround neurons and hold them in places, manufacture nutrient chemicals that neurons need, form the myelin sheath around axons, and absorb toxins and waste materials that might damage neurons.
Blood-brain barrier:
Prevents many substances, including a wide range of toxins, from entering the brain. The walls of the blood vessels within the brains contain smaller gaps and are covered by specialized glial cells.
Resting potential:
The electrical activity of neurons, the internal diffence of the sodium ions outside of a cell and the negatively charged protein ions inside the cell
Action potential:
A nerve impulse resulting from the depolarization of an axon’s cell membrane
Depolarization:
The shift from negative to positive voltage
All or none law:
The fact that an action potential is not proportional to the intensity of stimulation. A neuron either fires with max intensity or it does not fire at all.
Myelin Sheath:
A fatty, whitish insulation layer around axons and interrupted at regular intervals by the node of Ranvier.
Synapse:
the microscopic space between neurons over which the nerve impulse is biochemically transmitted
Neurotransmitters:
Chemical substances that carry messages cross the synapse to either excite other neurons or inhibit their firing
Multiple sclerosis:
neurological disorder characterized by demyelination of axons because immune system attacks myelin sheath
Five Step process of chemical communication between neurons
- Synthesis: chemical molc. are formed inside neuron
- Storage: Molc. stored in chambers called synaptic vesicales within axon terminal.
- Release: Molc. released into space between axon and membrane of receiving neuron
- Binding: Molc. cros synaptic space and attach to receptor sites
- Deactiviation.
Excitatory Neurotransmitter:
Depolarizes neurons’s membrane which increases likelihood of action potential.
Inhibitory neurotransmitter:
Hyper polarizes neuron’s membrane which decreases likelihood of action potential.
Glutmatic acid:
Excitatory neurotransmitter, involved in control of all behaviours, especially important in learning and memory
GABA (Gammaaminobutyric acid):
Inhibitory transmitter, important in anxiety and motor control. Destruction in Huntington’s disease produces tremors and loos of motor control, as well as personality changes.
Acetylcholine:
Excitatory at synapses involved in muscular movement and memory. Memory loss in Alzheimer’s disease (undersupply) or muscle contractions (oversupply)
Norepinephrine:
Involved in neural circuits controlling learning, memory, wakefulness, and eating. Depression (undersupply) or stress and panic disorders (oversupply)
Serotonin:
Involved in mood, sleep, eating, and arousal, may be important in pain and pleasure. Depression, sleeping, and eating disorders (undersupply)
Dopamine:
Involved in voluntary movement, emotional arousal, leaning, motivation, experiencing pleasure. Parkinson’s disease and depression (undersupply) Schizophrenia (oversupply)
Endorphins:
Inhibits transmission of pain impulses. Insensitivity to pain (oversupply) Pain hypersensitivity, immune problems (oversupply)
Three major types of neuron
- Sensory neurons: carry input messages from sense organs to the spinal cord and brain
- Motor neurons: transmit out impulses from the brain and spinal cord to the body’s muscles and organs
- Interneurons: Perform connective functions within the nervous system
