Neuroanatomy: Study of the parts/function of a neuron.
Neuron: Nerve cells. Their parts are dendrites, soma, axon, Myelin sheath, and Terminal buttons.
Dendrites: Rootlike structures that form synaptic connections with other neurons
Soma: The body of the neuron, contains the nucleus and other cell organelles
Axon: Wirelike structure that connects the soma to the Terminal buttons
Myelin sheath: Fatty covering of the axon that speeds up neural impulses
Terminal buttons: End of the axon, contains neurotransmitters. Also called end buttons, terminal branches of axon, and synaptic nobs
Neurotransmitters: Chemicals in the Terminal buttons that allow neurons to communicate, fit into the dendrites
Synapse: The space between the terminal button of one neuron and the dendrites of another
In a resting state, a neuron is slightly negative, with more negative ions on the inside, surrounded by positive ions. The cell membrane keeps the positive ions out through selective permeability. 1. Terminal buttons of Neuron A are stimulated. They release neurotransmitters into the synapse 2. The neurotransmitters enter the dendrite receptors of Neuron B 3. If the “threshold” of neurotransmitters is reached in Neuron B, Neuron B becomes totally permeable. (This is called the all-or-none principle; either the neuron totally fires, or it does not fire. It all depends on whether the threshold is reached.) 4. Positive ions flood Neuron B. The charge moving through the neuron is called action potential, and moves 120 m/s 5. When the charge reaches the terminal buttons, they stimulate them, causing them to release neurotransmitters into the next synapse.
Excitatory neurotransmitters: Chemicals that excite neurons into firing Inhibitory neurotransmitters: Inhibit neurons from firing
The amounts of transmitters, and their type, determine whether the threshold is reached, as a synapse will contain a mixture of excitatory and inhibitory transmitters.
Acetylcholine: A neurotransmitter that is connected to motor movement. A lack of it is associated with Alzheimer’s Dopamine: Connected to motor movement and alertness. A lack of it is connected with Parkinson’s, an abundance is linked with schizophrenia Endorphins: Connected to pain control, involved in addictions Serotonin: Mood control, lack of serotonin associated with depression
The Nervous System
Afferent Neurons/Sensory Neurons: Take information from our senses to the brain
Interneurons: Once information reaches the brain/spinal cord, these take it and send it through the brain/to efferent neurons
Efferent neurons: Take information from the brain to the rest of the body
The Nervous system is divided between the Central and Peripheral Nervous System
Central Nervous System
Consists of the brain and spinal cord
Peripheral Nervous System
Consists of all the other nerves in the body (not encased in bone). Divided between the somatic and autonomic nervous systems; the autonomic is further divided between the sympathetic and parasympathetic systems.
Somatic Nervous System
Voluntary muscle movements. It is directed by impulses from the motor cortex of the brain.
Autonomic Nervous System
Controls the automatic functions of the body. Made up of sympathetic and parasympathetic nervous system. Sympathetic Nervous System
Mobilizes the body to respond to stress. Accelerates things like heart rate blood pressure and respiration, while slowing down digestion and other functions to conserve resources.
Parasympathetic Nervous System
Slows the body down after stress responses. Essentially the brakes of the autonomic nervous system, while the sympathetic nervous system is the gas pedal.
EXAMPLE: You are walking and stub your toe. Sensory neurons in your toe transfer information up to your spine through afferent nerves. It then moves up the spine on more...