{"id":59,"date":"2025-11-18T20:02:20","date_gmt":"2025-11-18T20:02:20","guid":{"rendered":"https:\/\/press.wpunj.edu\/animalphysiologylabmanual\/chapter\/__unknown__-2\/"},"modified":"2025-11-18T20:06:14","modified_gmt":"2025-11-18T20:06:14","slug":"__unknown__-2","status":"publish","type":"chapter","link":"https:\/\/press.wpunj.edu\/animalphysiologylabmanual\/chapter\/__unknown__-2\/","title":{"raw":"Lab 2: Action Potential","rendered":"Lab 2: Action Potential"},"content":{"raw":"
\r\n

Step 1:<\/strong> Read the background information before starting the first activity.<\/p>\r\n\r\n

Exercise Overview:<\/h2>\r\n

The nervous system contains two general types of cells: neurons<\/strong> and neuroglia (or glial cells). This exercise focuses on neurons. Neurons respond to their local environment by generating an electrical signal. For example, sensory neurons in the nose generate a signal (called a receptor potential<\/strong>) when odor molecules interact with receptor proteins on the membrane of these olfactory sensory neurons. Thus, sensory neurons can respond directly to sensory stimuli. The receptor potential can trigger another electrical signal (called an action potential<\/strong>), which travels along the membrane of the sensory neuron's axon to the brain - you could say that the action potential is conducted to the brain.<\/p>\r\n

\"image\"<\/p>\r\n

The action potential causes the release of chemical neurotransmitters<\/strong> onto neurons in olfactory regions of the brain. These chemical neurotransmitters bind to receptor proteins on the membrane of these brain interneurons<\/strong>. In general, interneurons respond to chemical neurotransmitters released by other neurons. In the nose the odor molecules are sensed by sensory neurons. In the brain the odor is perceived by the activity of interneurons responding to neurotransmitters. Any resulting action or behavior is caused by the subsequent activity of motor neurons<\/strong>, which can stimulate muscles to contract (see Exercise 2).<\/p>\r\n

In general, each neuron has three functional regions for signal transmission: a receiving region, a conducting region, and an output region, or secretory region. Sensory neurons often have a receptive ending specialized to detect a specific sensory stimulus, such as odor, light, sound, or touch. The cell body<\/strong> and dendrites<\/strong> of interneurons receive stimulation by neurotransmitters at structures called chemical synapses<\/strong> and produce synaptic potentials<\/strong>. The conducting region is usually an axon<\/strong>, which ends in an output region (the axon terminal) where neurotransmitter is released.<\/p>\r\n

\"image\"<\/p>\r\n

Although the neuron is a single cell surrounded by a continuous plasma membrane, each region contains distinct membrane proteins that provide the basis for the functional differences. Thus, the receiving end has receptor proteins and proteins that generate the receptor potential, the conducting region has proteins that generate and conduct action potentials, and the output region has proteins to package and release neurotransmitters. Membrane proteins are found throughout the neuronal membrane-many of these proteins transport ions (see Exercise I).<\/p>\r\n

The signal generated and conducted by neurons are electrical. In ordinary household devices, electric current is carried by electrons. In biological systems, currents are carried by positively or negatively charged ions<\/strong>. Like charges repel each other and opposite charges attract. In general, ions cannot easily pass through the lipid bilayer of the plasma membrane and must pass through ion channels<\/strong> formed by integral membrane proteins. Some channels are usually open (leak channels), and others are gated, meaning that the channel can be in an open or closed configuration. Channels can also be selective for which ions are allowed to pass. For example, sodium channels are mostly permeable to sodium ions when open, and potassium channels are mostly permeable to potassium ions when open. The term conductance<\/strong> is often used to describe permeability.<\/strong> ln general, ions will flow through an open channel from a region of higher concentration to a region of lower concentration (see Exercise 1). In this exercise you will explore some of these characteristics applied to neurons.<\/p>\r\n

Although it is possible to measure the ionic currents through the membrane (even the currents passing through single ion channels), it is more common to measure the potential difference. or voltage, across the membrane. This membrane voltage is usually called the membrane potential<\/strong>, and the units are in millivolts (mV)<\/strong>. One can think of the membrane as a battery, a device that separates and stores charge. A typical household battery has a positive and a negative pole so that when it is connected, for example through a lightbulb in a flashlight, current flows through the bulb. Similarly, the plasma membrane can store charge and has a relatively positive side and a relatively negative side. Thus, the membrane is said to be polarized<\/strong>. When these two sides (intracellular and extracellular) are connected through open ion channels. current in the form of ions can flow in or out across the membrane and thus change the membrane voltage.<\/p>\r\n

\"image\"<\/p>\r\n

Step 2:<\/strong> in the PhysioEx 10.0 software on the desktop of the computer, open it, and click on Exercise 3: Neurophysiology of Nerve Impulses.<\/strong> Start with the first activity and be sure to take the pre and post-lab quizzes.<\/p>\r\n

You can skip the second activity and then complete activities 3-8 of Exercise 3: Neurophysiology of Nerve Impulses<\/strong> from the PhysioEx 10.0 software on the desktop of the computer.<\/p>\r\n

Step 3:<\/strong> record the data obtained from the activities in the tables in your lab report document that will be graded for accuracy as you complete the activities<\/strong>. In addition, be sure to complete the questions at the end of the lab report and to ask any questions you may have about these during the lab session as these will be graded as well.<\/p>\r\n

<\/p>\r\n\r\n<\/div>","rendered":"

\n

Step 1:<\/strong> Read the background information before starting the first activity.<\/p>\n

Exercise Overview:<\/h2>\n

The nervous system contains two general types of cells: neurons<\/strong> and neuroglia (or glial cells). This exercise focuses on neurons. Neurons respond to their local environment by generating an electrical signal. For example, sensory neurons in the nose generate a signal (called a receptor potential<\/strong>) when odor molecules interact with receptor proteins on the membrane of these olfactory sensory neurons. Thus, sensory neurons can respond directly to sensory stimuli. The receptor potential can trigger another electrical signal (called an action potential<\/strong>), which travels along the membrane of the sensory neuron’s axon to the brain – you could say that the action potential is conducted to the brain.<\/p>\n

\"image\"<\/p>\n

The action potential causes the release of chemical neurotransmitters<\/strong> onto neurons in olfactory regions of the brain. These chemical neurotransmitters bind to receptor proteins on the membrane of these brain interneurons<\/strong>. In general, interneurons respond to chemical neurotransmitters released by other neurons. In the nose the odor molecules are sensed by sensory neurons. In the brain the odor is perceived by the activity of interneurons responding to neurotransmitters. Any resulting action or behavior is caused by the subsequent activity of motor neurons<\/strong>, which can stimulate muscles to contract (see Exercise 2).<\/p>\n

In general, each neuron has three functional regions for signal transmission: a receiving region, a conducting region, and an output region, or secretory region. Sensory neurons often have a receptive ending specialized to detect a specific sensory stimulus, such as odor, light, sound, or touch. The cell body<\/strong> and dendrites<\/strong> of interneurons receive stimulation by neurotransmitters at structures called chemical synapses<\/strong> and produce synaptic potentials<\/strong>. The conducting region is usually an axon<\/strong>, which ends in an output region (the axon terminal) where neurotransmitter is released.<\/p>\n

\"image\"<\/p>\n

Although the neuron is a single cell surrounded by a continuous plasma membrane, each region contains distinct membrane proteins that provide the basis for the functional differences. Thus, the receiving end has receptor proteins and proteins that generate the receptor potential, the conducting region has proteins that generate and conduct action potentials, and the output region has proteins to package and release neurotransmitters. Membrane proteins are found throughout the neuronal membrane-many of these proteins transport ions (see Exercise I).<\/p>\n

The signal generated and conducted by neurons are electrical. In ordinary household devices, electric current is carried by electrons. In biological systems, currents are carried by positively or negatively charged ions<\/strong>. Like charges repel each other and opposite charges attract. In general, ions cannot easily pass through the lipid bilayer of the plasma membrane and must pass through ion channels<\/strong> formed by integral membrane proteins. Some channels are usually open (leak channels), and others are gated, meaning that the channel can be in an open or closed configuration. Channels can also be selective for which ions are allowed to pass. For example, sodium channels are mostly permeable to sodium ions when open, and potassium channels are mostly permeable to potassium ions when open. The term conductance<\/strong> is often used to describe permeability.<\/strong> ln general, ions will flow through an open channel from a region of higher concentration to a region of lower concentration (see Exercise 1). In this exercise you will explore some of these characteristics applied to neurons.<\/p>\n

Although it is possible to measure the ionic currents through the membrane (even the currents passing through single ion channels), it is more common to measure the potential difference. or voltage, across the membrane. This membrane voltage is usually called the membrane potential<\/strong>, and the units are in millivolts (mV)<\/strong>. One can think of the membrane as a battery, a device that separates and stores charge. A typical household battery has a positive and a negative pole so that when it is connected, for example through a lightbulb in a flashlight, current flows through the bulb. Similarly, the plasma membrane can store charge and has a relatively positive side and a relatively negative side. Thus, the membrane is said to be polarized<\/strong>. When these two sides (intracellular and extracellular) are connected through open ion channels. current in the form of ions can flow in or out across the membrane and thus change the membrane voltage.<\/p>\n

\"image\"<\/p>\n

Step 2:<\/strong> in the PhysioEx 10.0 software on the desktop of the computer, open it, and click on Exercise 3: Neurophysiology of Nerve Impulses.<\/strong> Start with the first activity and be sure to take the pre and post-lab quizzes.<\/p>\n

You can skip the second activity and then complete activities 3-8 of Exercise 3: Neurophysiology of Nerve Impulses<\/strong> from the PhysioEx 10.0 software on the desktop of the computer.<\/p>\n

Step 3:<\/strong> record the data obtained from the activities in the tables in your lab report document that will be graded for accuracy as you complete the activities<\/strong>. In addition, be sure to complete the questions at the end of the lab report and to ask any questions you may have about these during the lab session as these will be graded as well.<\/p>\n

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