Physiology Quiz Chapter 5

The Central Nervous System (CNS) is composed of the brain and spinal cord. It is responsible for processing and coordinating information received from the sensory organs and sending out instructions to the rest of the body. The brain is the control center of the CNS, while the spinal cord serves as a communication pathway between the brain and the body. Therefore, the statement that the CNS consists of the brain and spinal cord is true.

Axons are long, slender extensions of nerve cells that transmit electrical impulses away from the cell body to other neurons, muscles, or glands. They are responsible for carrying information from one part of the body to another, allowing for communication between different regions. Axons are covered by a fatty substance called myelin, which helps to insulate and speed up the transmission of the impulses. Overall, axons play a crucial role in the functioning of the nervous system by transmitting signals and coordinating various bodily functions.

The statement is true because neurotransmitters are chemical messengers that transmit signals between neurons or from neurons to effector cells. When a neurotransmitter is released into the synapse, it can either excite or inhibit the post-synaptic neuron or effector cell. Excitatory neurotransmitters increase the likelihood of an action potential being generated, while inhibitory neurotransmitters decrease the likelihood. Therefore, the statement accurately describes the effects of neurotransmitters on the post-synaptic neuron or effector cell.

The autonomic nervous system is responsible for regulating involuntary bodily functions such as heart rate, digestion, and glandular secretion. It consists of nerve fibers that control the activity of smooth muscles, cardiac muscles, and glands. Therefore, the statement that the autonomic nervous system controls the activity of these muscles and glands is true.

Neurons are indeed highly excitable and produce electrical impulses when stimulated. These impulses, also known as nerve impulses or action potentials, are generated in response to changes in the neuron's membrane potential. Once initiated, the impulse is conducted down the length of the axon, allowing for communication between neurons and the transmission of signals throughout the nervous system.

Spinal nerves carry information to and from the spinal cord. The spinal cord is a long, tubular bundle of nerves that runs within the spine. It is responsible for transmitting signals between the brain and the rest of the body. The spinal nerves emerge from the spinal cord and branch out to various parts of the body, allowing for communication and coordination of sensory and motor functions. Therefore, the correct answer is "Spinal."

An axon is a long, slender projection of a nerve cell that conducts electrical impulses away from the cell body. Axons can vary in length, ranging from a few millimeters to more than one meter.

Schwann cells are responsible for forming myelin sheaths in the peripheral nervous system (PNS). Myelin sheaths are protective coverings that surround and insulate nerve fibers, allowing for faster and more efficient transmission of electrical impulses. Schwann cells wrap around the nerve fibers, forming multiple layers of myelin that make up the myelin sheath. This insulation is crucial for the proper functioning of the nervous system and ensures the smooth transmission of signals between the brain, spinal cord, and the rest of the body.

Visceral afferents are nerve fibers that transmit information from the internal organs to the central nervous system (CNS). These fibers carry sensory signals from organs such as the heart, lungs, and digestive system to the brain and spinal cord. This information is crucial for the CNS to regulate and coordinate the body's internal processes. Somatic afferents, on the other hand, carry sensory information from the skin, muscles, and joints to the CNS. Therefore, the correct answer is visceral afferents as they specifically refer to the nerve fibers responsible for transmitting information from the visceral organs to the CNS.

Motor nerves are responsible for carrying nerve impulses away from the central nervous system (CNS) to the muscles and glands, allowing for movement and coordination. These nerves transmit signals from the brain and spinal cord to the muscles, enabling voluntary and involuntary muscle contractions. Unlike sensory nerves, which carry impulses towards the CNS, motor nerves exclusively carry impulses away from the CNS. Mixed nerves, on the other hand, contain both sensory and motor fibers, allowing for bidirectional transmission of signals.

Hyperpolarization is the correct answer because it refers to an increase in the membrane potential or the membrane potential becoming more negative. This means that the inside of the cell becomes more negative compared to the outside, making it less likely for an action potential to occur. Hyperpolarization can be caused by the opening of potassium channels, which allows potassium ions to leave the cell, or by the influx of chloride ions into the cell. Overall, hyperpolarization leads to a decrease in excitability and a decrease in the likelihood of an action potential being generated.

The correct answer is "Peripheral Nervous System and Central Nervous System". The nervous system is divided into two main parts: the peripheral nervous system (PNS) and the central nervous system (CNS). The PNS consists of all the nerves outside of the brain and spinal cord, including sensory and motor nerves. It helps transmit information between the CNS and the rest of the body. On the other hand, the CNS includes the brain and spinal cord, which process and interpret information received from the PNS and control body functions.

The explanation for the given correct answer is that the Peripheral Nervous System serves as a communication network between the body's various parts and the Central Nervous System. It consists of nerves that extend from the brain and spinal cord to the rest of the body, allowing for the transmission of signals and information. This system plays a crucial role in coordinating movement, transmitting sensory information, and regulating bodily functions.

Changes in membrane potential can indeed act as communication signals. Neurons, for example, use changes in membrane potential to transmit electrical signals, known as action potentials, which allow for the transmission of information throughout the nervous system. These changes can be either negative (hyperpolarization) or positive (depolarization) in relation to the resting membrane potential, depending on the specific circumstances and stimuli. Therefore, the statement is true.

The somatic nervous system is responsible for controlling voluntary movements of the skeletal muscles. It consists of nerve fibers that carry signals from the central nervous system (CNS) to the skeletal muscles, allowing us to consciously control our movements. This system plays a crucial role in activities such as walking, running, and lifting objects. Therefore, the statement "The somatic nervous system are nerve fibers that carry impulses from the CNS to the skeletal muscles" is true.

Schwann cells are separated from one another by nodes of Ranvier. These nodes are gaps between the Schwann cells.

The myelin sheath is a whitish, fatty segmented covering that surrounds the axon of neurons. It acts as an insulating layer, allowing for faster transmission of electrical signals along the axon. The myelin sheath is formed by specialized cells called oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system. This protective covering is crucial for the proper functioning of the nervous system and helps to enhance the efficiency of nerve signal conduction.

Motor or efferent neurons are responsible for transmitting nerve impulses from the central nervous system (CNS) to the effector organs, which can be muscles or glands. These neurons carry signals that initiate and control movement or response in the body. Unlike sensory or afferent neurons that carry signals from sensory organs to the CNS, motor neurons transmit signals in the opposite direction, allowing the CNS to control and coordinate the body's actions.

The Autonomic Nervous System is responsible for controlling the involuntary functions of the body, such as heart rate, digestion, and breathing. It operates without conscious control and regulates these bodily processes automatically. Therefore, it is commonly referred to as the involuntary nervous system.

A neuron is a specialized type of cell that is responsible for transmitting nerve impulses from one part of the body to another. It is the basic building block of the nervous system and plays a crucial role in allowing communication between different parts of the body. Neurons have a unique structure with dendrites that receive signals, an axon that transmits signals, and synapses that allow for communication with other neurons. Through this process, neurons enable the transmission of information and coordination of various bodily functions.

Sensory nerves are responsible for carrying nerve impulses from the body's sensory organs, such as the eyes, ears, and skin, towards the central nervous system (CNS). These nerves transmit information about sensations such as touch, temperature, pain, and pressure to the brain and spinal cord, allowing us to perceive and respond to our environment. Unlike motor nerves, which carry impulses away from the CNS to control muscles and glands, sensory nerves only transmit information towards the CNS. Mixed nerves, on the other hand, contain both sensory and motor fibers, carrying impulses in both directions.

The axon hillock is a cone-shaped region of the cell body where the axon originates. It is located between the cell body and the axon and plays a crucial role in the generation of action potentials. The axon hillock contains a high concentration of voltage-gated ion channels, which are responsible for the initiation and propagation of electrical signals along the axon. This region acts as a trigger zone, where the integration of incoming signals from the dendrites occurs. Once the electrical signals reach a certain threshold at the axon hillock, an action potential is generated and propagated down the axon.

Sensory or afferent neurons are responsible for transmitting nerve impulses from sensory receptors towards the central nervous system (CNS). These neurons play a crucial role in allowing us to perceive and respond to various stimuli from our environment. They transmit information about touch, temperature, pain, and other sensory inputs to the CNS, where it is processed and interpreted. This allows us to become aware of our surroundings and initiate appropriate motor responses. Motor or efferent neurons, on the other hand, transmit nerve impulses from the CNS to muscles and glands, enabling us to carry out voluntary and involuntary movements.

Schwann cells are a type of cells in the peripheral nervous system that surround and cover nerve fibers. They play a crucial role in providing support and insulation to nerve fibers, aiding in the transmission of nerve impulses. Schwann cells also help in the regeneration of damaged nerves. Therefore, Schwann cells are the correct answer in this context.

White matter refers to the regions of the central nervous system (CNS) that contain a high concentration of myelinated nerve fibers. Myelinated fibers appear white due to the presence of the myelin sheath, which helps to speed up the transmission of nerve impulses. In contrast, gray matter consists of neuronal cell bodies, dendrites, and unmyelinated axons. Therefore, the correct answer is white matter.

The central nervous system is responsible for integrating and coordinating the activities of the entire nervous system. It consists of the brain and spinal cord, which receive and process information from the peripheral nervous system and send out commands to the body. The central nervous system plays a crucial role in regulating and controlling bodily functions, as well as processing sensory information and generating responses.

The given correct answer is "Sensory or afferent neurons." This is because the description provided in the question matches the characteristics of sensory or afferent neurons. These neurons have unipolar morphology, with their cell bodies located in sensory ganglia outside of the spinal cord. They receive nerve impulses at their dendrites and transmit them through their long, myelinated axons to and away from the cell body. Additionally, the dendrite of a sensory neuron may serve as a sensory receptor, further supporting the classification of these neurons as sensory or afferent.

Mixed nerves contain both sensory and motor fibers, allowing them to transmit impulses to and from the central nervous system (CNS). This means that they can carry sensory information from the body to the CNS, such as touch or pain sensations, and also transmit motor signals from the CNS to the muscles or glands, enabling movement or other responses. Mixed nerves are crucial for the integration and coordination of sensory and motor functions in the body.

The potential difference between the inside and outside of a neuron is referred to as voltage. This voltage is observed as a difference in electrical charge across the cell membrane, which is known as the resting membrane potential.

This statement is true because while most neurons release only one type of neurotransmitter, there are some neurons that are capable of releasing more than one neurotransmitter. These neurons are known as co-transmitters or multi-transmitters. The ability to release multiple neurotransmitters allows for more complex and diverse signaling within the nervous system.

Myelin is a substance that protects and insulates the axon, which is the long, slender part of a nerve cell. It acts as an electrical insulator, allowing nerve impulses to travel more efficiently along the axon. The presence of myelin greatly increases the speed at which nerve impulses can be transmitted, enabling faster communication between different parts of the nervous system.

Depolarization refers to a reduction in the membrane potential or the inside of the membrane becoming less negative. This occurs when there is an influx of positive ions into the cell or an efflux of negative ions. As a result, the membrane potential approaches zero or becomes less negative. Therefore, depolarization is the correct answer in this context.

Supporting cells are nonexcitable cells that surround neurons and provide structural support and protection to the nervous tissue. They form the scaffolding of the nervous system, helping to maintain the shape and organization of neurons. These cells also play important roles in regulating the chemical environment around neurons and assisting in their proper functioning. While dendrites are part of neurons and bacteria are unrelated to the nervous tissue, supporting cells are specifically responsible for providing support and maintaining the integrity of the nervous system.

Cranial nerves carry information to and from the brain. These nerves originate from the brain and extend to various parts of the head and neck. They are responsible for controlling sensory and motor functions in the face, head, and neck regions. The cranial nerves play a vital role in transmitting information related to vision, hearing, taste, smell, and facial movements to the brain, as well as controlling muscles involved in chewing, swallowing, and speaking.

Perikaryon is another term used to refer to the cell body. The cell body, also known as the soma, is the main part of a neuron that contains the nucleus and other organelles essential for the cell's functioning. It is responsible for maintaining the overall health and metabolism of the neuron, as well as integrating and processing incoming signals from dendrites before transmitting them to the axon. Therefore, perikaryon and cell body are interchangeable terms used to describe this crucial component of a neuron.

The axon hillock is the region of a neuron where nerve impulses are generated. It acts as a trigger zone for the initiation of action potentials. Once the impulse is generated, it is conducted along the axon, which is the long, slender projection of the neuron, to the axon terminals. The axon terminals are responsible for transmitting the impulse to other neurons or target cells. Therefore, the axon hillock and axon work together to generate and transmit nerve impulses within the nervous system.

The correct answer is the sensory or afferent division. This division of nerve fibers carries sensory information from peripheral sensory receptors to the central nervous system (CNS). These sensory fibers transmit signals related to touch, temperature, pain, and other sensory stimuli from various parts of the body to the brain and spinal cord for processing and interpretation.

A synapse is the junction where information is passed from one neuron to another neuron or from a neuron to an effector cell. It is a small gap between the axon terminal of one neuron and the dendrite or cell body of another neuron or an effector cell. Neurotransmitters are released from the axon terminal into the synapse and bind to receptors on the dendrite or cell body, allowing the transmission of signals. This allows for communication and coordination between neurons and the transmission of signals throughout the nervous system.

Astrocytes are star-shaped cells that are found in the central nervous system (CNS) and make up about 50% of the nervous tissue volume. They provide structural and metabolic support to neurons, regulate the extracellular environment, and help maintain the blood-brain barrier. Astrocytes also play a role in synaptic transmission and modulate neuronal activity. Due to their diverse functions, astrocytes are essential for the proper functioning of the CNS.

Pacinian corpuscles are the type of receptor responsible for sensing deep pressure. These specialized nerve endings are found in the skin and other tissues, particularly in areas where deep pressure is applied. They are highly sensitive to changes in pressure and are able to detect vibrations and rapid changes in pressure, making them well-suited for sensing deep pressure. Pacinian corpuscles consist of a nerve ending surrounded by layers of connective tissue, which allows them to detect and transmit signals related to deep pressure to the brain.

The somatic nervous system is responsible for the voluntary control of skeletal muscles and the reception of external stimuli. It allows us to consciously move our muscles and respond to sensory information from our environment. This system is under our conscious control, enabling us to make deliberate movements and actions. Therefore, the term "voluntary nervous system" accurately describes the somatic nervous system.

Dendrites are short, thick, branching cytoplasmic extensions that act as receptive sites. They receive nerve impulses and conduct them toward the cell body.

Oligodendrocytes are responsible for forming myelin sheaths in the central nervous system (CNS). These cells can form up to 60 different myelin sheaths on different axons simultaneously. Additionally, there are nodes of Renvier between these myelin sheaths.

Ependymal cells are responsible for producing cerebrospinal fluid (CSF) and circulating it through the central cavities of the brain and spinal cord. They have cilia that help in the movement and circulation of the CSF. Schwann cells are responsible for producing myelin in the peripheral nervous system, satellite cells provide support and protection to neurons in the peripheral nervous system, and oligodendrocytes produce myelin in the central nervous system. Therefore, the correct answer is ependymal cells.

Somatic afferents are nerve fibers that carry sensory information from the skin, muscle, or joint to the central nervous system (CNS). This means that they transmit information about sensations such as touch, pain, temperature, and proprioception from the external environment to the brain and spinal cord. Visceral afferents, on the other hand, carry sensory information from the internal organs to the CNS. Therefore, the correct answer is somatic afferents because they specifically refer to the nerve fibers that carry sensory information from the skin, muscle, or joint.

The statement is false because the somatic nervous system is responsible for controlling voluntary movements of skeletal muscles, not smooth muscles, cardiac muscles, and glands. The autonomic nervous system, on the other hand, controls the activity of smooth muscles, cardiac muscles, and glands.

Sensory receptors are specialized neurons with dendritic end organs that detect changes in the environment or stimuli. These receptors are responsible for sensing sensory input and converting it into electrical signals that can be processed by the nervous system. This sensory input is then used to generate sensory output, which helps the organism respond to the stimuli in its environment. Therefore, sensory receptors play a crucial role in the sensory system by detecting and transmitting sensory information to the brain.

The resting membrane potential in neurons is -70 mV, which means that the inside of the cell membrane is more negative than the outside of the cell. This negative charge is maintained by the selective permeability of the cell membrane to different ions, such as potassium and sodium. The concentration gradients of these ions, along with the activity of ion channels and pumps, contribute to the establishment and maintenance of the resting membrane potential.

Motor or efferent neurons are responsible for carrying signals from the central nervous system (CNS) to the muscles and glands in the body, causing them to respond. These neurons have cell bodies located in the CNS and long axons that extend out to the target organs. This allows them to transmit signals and initiate movement or other responses. In contrast, sensory or afferent neurons carry signals from sensory receptors to the CNS, providing information about the external environment or internal body conditions. Therefore, the given answer is correct as it accurately describes motor or efferent neurons.

Gray matter refers to the region of the central nervous system that contains neuron cell bodies and unmyelinated nerve fibers. It is called gray matter because it appears grayish in color due to the presence of cell bodies and dendrites. Gray matter is responsible for processing and integrating information in the brain, including sensory perception, memory, and decision-making. On the other hand, white matter consists of myelinated nerve fibers and is responsible for transmitting signals between different regions of the brain and spinal cord.