Understanding the Nervous System and Brain Function
Membrane Potential and Neuronal Function
1. What is a Membrane Potential?
The membrane potential is the electrical charge of the inside of a cell relative to the outside of the cell.
2. What is the membrane potential at these stages?
- a. Rest: -70mV
- b. The end of Depolarization: +30mV
- c. The end of Repolarization: -70mV
- d. Hyperpolarization: More negative than -70mV
3. In a single round of the Sodium-Potassium pump, which elements (and how many) move through the plasma membrane?
3 sodium ions (Na+) move out, and 2 potassium ions (K+) move in.
4. What is the purpose of the sodium-potassium pump?
To maintain the -70mV resting membrane potential, ensuring a higher concentration of sodium ions outside the cell and a higher concentration of potassium ions inside the cell.
5. Why are some neurons myelinated?
Myelin allows action potentials to move faster and remain stronger. The action potential jumps from one Node of Ranvier to the next (saltatory conduction), increasing speed. Signal strength is maintained because the signal is boosted at each node.
6. What is a synapse, and what happens there?
A synapse is the gap between an axon terminal and the next neuron (or target cell). When an action potential reaches the axon terminal, a neurotransmitter is released. This neurotransmitter travels across the synapse and binds to chemically-gated channels on the postsynaptic cell. The channels open, allowing ions to enter or exit the cell, influencing the postsynaptic cell’s membrane potential.
Divisions and Components of the Nervous System
7. What are the two principal parts of the Nervous System?
The Central Nervous System (CNS) and the Peripheral Nervous System (PNS).
8. What is the Somatic Nervous System?
The Somatic Nervous System controls voluntary movements of skeletal muscles.
9. What is the Autonomic Nervous System?
The Autonomic Nervous System controls involuntary functions, such as heart rate, digestion, and respiration. It includes all the body parts that function automatically.
10. Which cells connect to blood vessels and neurons?
Astrocytes.
11. Which cells wrap axons in myelin in the CNS? In the PNS?
- CNS: Oligodendrocytes
- PNS: Schwann Cells
12. What is the function of Dendrites?
To gather signals (input) from other neurons.
13. What is the difference between postsynaptic inhibitory potentials (IPSPs) and postsynaptic excitatory potentials (EPSPs)?
IPSPs cause the neuron’s membrane potential to become more negative (hyperpolarization), decreasing the likelihood of an action potential. EPSPs cause the membrane potential to become more positive (depolarization), increasing the likelihood of an action potential.
14. What is a graded potential?
A small voltage change in a postsynaptic cell that is not sufficient to trigger an action potential.
15. What are the 5 steps of a Simple Reflex Arc?
- Receptor
- Sensory Neuron
- Integration Center
- Motor Neuron
- Effector
16. What are the 4 types of Neural Circuits?
- Diverging
- Converging
- Reverberating
- Parallel after-discharge
Brain Structure and Function
17. What is the location of White Matter, and what does it contain?
White matter is located in the interior of the brain and the exterior of the spinal cord. It contains myelinated axons.
18. What is the location of Gray Matter, and what does it contain?
Gray matter is located on the exterior of the brain and the center of the spinal cord. It contains mostly neuron cell bodies and unmyelinated axons.
19. What is the name of the structures that contain cerebrospinal fluid, and how many are there?
There are four Ventricles.
20. What is the difference between Gyri and Sulci?
Gyri are the bumps (ridges) on the surface of the brain. Sulci are the grooves.
21. Label the areas of the brain on the diagram.
(This question requires a diagram and cannot be answered in text.)
22. What does the central sulcus divide?
The primary motor cortex and the primary somatosensory cortex.
23. What is a Homunculus?
A cortical homunculus is a visual representation of the body’s parts mapped onto the primary motor and primary sensory cortex, reflecting the proportion of brain area dedicated to each body part.
24. What is Proprioception?
The sense of knowing where your body is in space.
25. What is the Optic Chiasm?
The point where the optic nerves cross.
26. Which lobe is associated with vision?
The Occipital lobe.
Brain Regions and Associated Functions
27. What are the 3 sections of the Basal Nuclei?
- Caudate nucleus
- Putamen
- Globus pallidus
28. What are the 3 parts of the Diencephalon?
- Thalamus
- Hypothalamus
- Epithalamus
29. Label the diagram.
(This question requires a diagram and cannot be answered in text.)
30. What are the folds on the outside of the cerebellum called, and how are they different than sulci and gyri?
The folds are called Folia. They are much thinner and more tightly packed than the gyri and sulci of the cerebrum.
31. What are Cerebellar Peduncles?
Fiber tracts that connect the cerebellum to the brainstem.
32. What is the main function of the limbic system?
Emotions, memory, and motivation.
33. What is the main function of Broca’s area? And Wernicke’s area?
- Broca’s area: Speech production.
- Wernicke’s area: Language comprehension.
Memory, Meninges, and Sensory Processing
34. What are the kinds of memory?
- a. Declarative (fact) memory (names, faces, words, dates)
- b. Procedural (skills) memory (playing piano)
- c. Motor memory (memory of motor skills, like riding a bike)
- d. Emotional memory (memory of experiences linked to an emotion, like your heart pounding when you hear a rattlesnake)
35. What is the difference between Anterograde and Retrograde amnesia?
- Anterograde amnesia: The inability to form new memories, but old memories are retained.
- Retrograde amnesia: The loss of past memories.
36. What are the three layers of the Meninges in order from outside to inside?
- Dura mater
- Arachnoid mater
- Pia mater
37. Where is cerebrospinal fluid made?
The Choroid Plexus.
38. Which spinal nerve root has sensory information? Motor?
- Sensory: Dorsal root
- Motor: Ventral root
39. What is the difference between Sensation and Perception?
- Sensation: The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment.
- Perception: The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.
40. Label the cranial nerves and list a function of each.
(This question requires a diagram of the 12 Cranial Nerves and cannot be fully answered in text. A complete answer would list each nerve: Olfactory, Optic, Oculomotor, Trochlear, Trigeminal, Abducens, Facial, Vestibulocochlear, Glossopharyngeal, Vagus, Accessory, Hypoglossal, and a brief function for each.)