structure and communication in the nervous system Flashcards
Talk about how the nervous system is organized.
The nervous system has two major branches: the central nervous system and the peripheral nervous system. While the CNS is mainly involved with the brain and the spinal cord, the PNS can be further divided: the somatic and autonomic nervous systems. While the somatic nervous system controls the skeletal muscles, such as helping us walk across a room, the autonomic nervous system has three branches: the sympathetic, parasympathetic, and enteric.
Explain how the central nervous system works.
Parts: Brainstem(medulla oblongota, midbrain, and pons), Cerebrum, Cerebellum.
Functions:
-Brainstem: a stalk-like part that joins the brain to the spinal cord.
-Cerebrum: the largest portion of the brain, divided into two hemispheres.
-Cerebellum: between the cerebrum and brainstem; learning and coordinating motor movements.
Explain how the peripheral nervous system works.
Parts: Afferent/sensory neurons, Efferent/Secretomotor neurons, Somatic system, Autonomic system.
Functions:
Additional:
What does the autonomic nervous system, with its branches, do?
The autonomic nervous system is responsible for supplying nerves to the cardiac muscle of the heart. It’s a part of the peripheral nervous system. The enteric branch is involved in the control of the digestive tract, while the sympathetic and parasympathetic is involved in our fight-or-flight response.
Explain the process of action potential.
Action potential is the process in which the membrane potential of a neuron rapidly rises and falls due to the movement of Na+(sodium) and K+(potassium) channels. It has three phases: depolarization, overshoot, and repolarization. These are all-or-none, since if the threshold potential, or the number of ion channels open leads to the system becoming self-sustaining, isn’t reached, no action potentials will occur. Even if there is a larger stimulus, it doesn’t mean that the action potentials would be larger, but rather its frequency would increase. How its fired would depend on excitatory neurotransmitters, or chemical substances, that make postsynaptic neurons more likely to fire action potentials. On the flip side, there are inhibitory neurotransmitters that make the postsynaptic neuron less likely to fire.
Explain the process of action potential (pt. 2)
The communication between the presynaptic neuron and the postsynaptic neuron happens at the junction called a synapse. There, the action potential arrives at the terminal button Vesicles release their neurotransmitters into the synapse, which then bind to receptors, large protein molecules, that have a specific, unique structure. Once the signal is delivered, excess neurotransmitters can go into a process called reuptake, which involves the neurotransmitter being pumped back into the neurons that released it.
Dive deep into how an action potential travels down a neuron.
An action potential is received by the dendrites, or these branch-like projections that conducts the stimulation received from other neural cells into the cell body, or the soma. Basically, small gates open on the neuronal membrane, allowing Na+ ions to move into the cell. These dendrites are always undergoing remodeling throughout one’s life span. Then, the action potential is propagated through its axon, or the projection that extends from the cell body to its ending and transmits the signal until it reaches the terminal button. Once this is depolarized, it releases a neurotransmitter into the synapse. It then binds to its receptors on the postsynaptic neuron of the target cell, causing either stimulation or inhibition depending on the kind of neurotransmitter. The speed of the propagation depends on the axon’s thickness and whether it’s myelinated. Myelin is the white fatty material that wraps around the axon that not only helps insulate it, but also allows rapid transmission along the axon. It’s produced from oligodendrocytes, a type of glial cell.
What is glutamate?
It’s the most abundant EXCITATORY neurotransmitter in the brain; binds to many receptors.
What is GABA/gamma-aminobutyric acid?
It’s the most abundant INHIBITORY neurotransmitter in the brain; binds to many receptors.
What is glycine?
A neurotransmitter that can either be excitatory OR inhibitory depending on the receptors. It can mirror GABA’s actions in the spinal cord and be a co-agonist for NMDA receptors.
What is dopamine?
It’s a monoamine neurotransmitter associated with motor control, determining the activity of the basal ganglia and behaviors related to reward and addiction. It has a lot of functions because it keeps our brain at its optimal level. Low levels: Parkinson’s disease.
What is serotonin?
It’s a monoamine neurotransmitter associated with mood, digestion, sleep, and psychological disorders. For example, if there are low levels, it can lead to depression. Low levels: depression.
What is acetylcholine?
Responsible for our motor movements. Low levels: Alzheimer’s.
