Lecture 1 Flashcards
Define afferent and efferent pathways in the nervous system. Provide examples of each.
Afferent pathways, also known as sensory pathways, transmit sensory information from sensory receptors to the central nervous system (CNS). For example, the pathway that carries pain signals from the skin to the spinal cord is an afferent pathway. Efferent pathways, on the other hand, transmit motor commands from the CNS to muscles and glands. An example is the pathway that sends signals from the brain to muscles for voluntary movement.
Differentiate between the dorsal and ventral pathways in the nervous system. How do these pathways relate to sensory input and motor output?
Dorsal Pathway: The dorsal pathway carries sensory input into the nervous system, such as sensory information from the skin or other body parts.
Ventral Pathway: The ventral pathway carries motor output out of the nervous system, transmitting commands to muscles and glands.
Explain the roles of the parasympathetic and sympathetic divisions of the autonomic nervous system. How do they differ in their functions?
The parasympathetic division of the autonomic nervous system is responsible for promoting relaxation and restoring the body to a state of rest. It is often associated with “rest and digest” functions, such as slowing the heart rate and promoting digestion. In contrast, the sympathetic division is responsible for arousal and preparing the body for “fight or flight” responses. It increases heart rate, dilates pupils, and redirects blood flow to muscles. These two divisions have opposing functions, helping maintain a balance in the body’s physiological processes.
Describe the structure and function of the cranial nerves and spinal nerves in the human nervous system.
Cranial nerves are a set of twelve pairs of nerves that connect directly to the brain and are responsible for various sensory and motor functions, such as controlling facial muscles, transmitting visual information, and regulating taste. Spinal nerves, of which there are thirty-one pairs, connect to the spinal cord and transmit signals between the brain and the rest of the body. They are responsible for both sensory input and motor output.
What is resting membrane potential in neurons? What factors contribute to the negative charge inside a neuron?
Resting membrane potential is the electrical charge difference across the membrane of a neuron when it is at rest. Typically, it is around -70 millivolts (mV). The negative charge inside the neuron is primarily due to the movement of ions, including sodium (Na+), potassium (K+), chloride (Cl-), and negatively charged proteins (A-). Sodium-potassium pumps and sodium-chloride pumps actively move ions across the membrane, contributing to the negative interior charge.
Explain the concept of action potentials and their threshold. What is the significance of the all-or-nothing principle?
Action potentials are rapid changes in the electrical charge of a neuron’s membrane. They are initiated when the membrane reaches a critical threshold, typically around -55 mV. Once the threshold is reached, an action potential occurs, following the all-or-nothing principle, meaning it is a full-blown response without gradations. Voltage-gated sodium channels play a crucial role in opening and closing during the generation of action potentials.
How does myelin impact the speed of action potentials in axons? What are nodes of Ranvier, and why are they significant?
Myelin, a fatty substance covering axons, acts as an insulator, allowing action potentials to propagate more quickly along the axon. Myelin prevents ion flow across the axonal membrane, except at specific gaps called nodes of Ranvier. These nodes serve as points where the action potential can “jump” from one node to the next, significantly increasing the speed of signal transmission.
What is multiple sclerosis (MS), and how does it affect the transmission of signals in the nervous system? What are some common symptoms of MS?
Multiple sclerosis is an autoimmune disorder that affects the central nervous system, specifically the myelin sheath surrounding nerve fibers. In MS, the immune system mistakenly attacks and damages the myelin, leading to disruptions in signal transmission. As a result, individuals with MS may experience symptoms such as numbness, muscle weakness, fatigue, and problems with coordination due to the slowed or blocked transmission of nerve signals.
Detail the Hodgkin-Huxley cycle during an action potential. What happens during depolarization and repolarization?
During an action potential, depolarization occurs when voltage-gated sodium channels open, allowing sodium ions (Na+) to rush into the neuron. Repolarization follows as these channels close, and potassium channels open, leading to hyperpolarization.
What is a sensory dermatome, and why is it important in understanding sensory perception?
A sensory dermatome is a map showing which nerves are responsible for specific areas of the skin. It is important for understanding sensory perception because it helps identify the source of sensory input and diagnose neurological conditions.
What are the major divisions of the brain
Forebrain: This includes the telencephalon and diencephalon. The forebrain is responsible for high-order processing, cognition, sensory perception, emotion, and behavior.
Midbrain: Positioned between the forebrain and hindbrain, the midbrain is involved in motor control, sensory processing, alertness, and arousal.
Hindbrain: The hindbrain comprises the metencephalon and myelencephalon. It is responsible for functions such as coordination, balance, breathing, heart rate regulation, and essential bodily functions.
What are the six layers of the neocortex?
Molecular Layer: Horizontal connections for information integration.
External Granular Layer: Small pyramidal neurons for sensory data integration.
External Pyramidal Layer: Medium-sized pyramidal neurons for interhemispheric communication.
Internal Granular Layer: Receives sensory inputs, specialized by senses.
Internal Pyramidal Layer: Sends motor commands and crucial for motor control.
Multiform Layer: Provides feedback to the thalamus, modulating sensory processing.
What is an EPSP (Excitatory Postsynaptic Potential) in the context of neuron communication, and how does it influence the behavior of a postsynaptic neuron?
An EPSP, or Excitatory Postsynaptic Potential, is a crucial part of how neurons communicate with each other. When one neuron wants to send a message to another, it releases chemicals called neurotransmitters at a synapse (the connection point between neurons). These neurotransmitters bind to receptors on the receiving neuron, which can have different effects.
In simple terms, EPSPs are the way neurons in your brain encourage each other to become active and pass messages along. They’re like little pushes that make the receiving neuron more likely to respond and pass on the message.
