Physiology Exam 2
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Questions and Answers

What keeps the membrane potential negative at -70mV to be specific?

  • Sodium ions (correct)
  • Potassium ions (correct)
  • Chloride ions
  • Calcium ions

    • What does the voltage-gated Na+ channel cause to the membrane potential?

  • Depolarization (correct)
  • Hyperpolarization
  • Stabilization
  • No change

    • What does the voltage-gated K+ channel cause to the membrane potential?

  • Repolorization (correct)
  • Depolarization
  • No change in membrane potential
  • Breakdown of the cell membrane

    • How is the neuron reset to its resting potential?

    <p>The potassium channels open and the sodium channels close. (reset of the distribution of Na+ (out) and K+ (in)</p> Signup and view all the answers

    Match the type of sensory neuron receptors with their corresponding stimuli:

    <p>Mechanoreceptors = respond to touch, pressure, vibration, stretch, and itch Thermoreceptors = are sensitive to changes in temperature Photoreceptors = respond to light energy Chemoreceptors = responds to chemicals, monitor oxygen levels and acidity levels in major blood vessels Nociceptors = sensitive to pain, causing stimuli Osmoreceptors = detect changes in concentration of solids and osmotic activity</p> Signup and view all the answers

    During an action potential, how many potassium ions are typically released into the extracellular fluid and how many sodium ions typically enter the cell?

    <p>2 potassium ions released, 3 sodium ions enter</p> Signup and view all the answers

    How is the strength of a stimulus coded?

    <p>By the frequency of action potentials</p> Signup and view all the answers

    What are the 3 primary functions of the nervous system in the human body?

    <p>Coordinates our movements, sense the environment, and integrate senses</p> Signup and view all the answers

    The Nervous System is divided into the ____________

    <p>Central Nervous System(CNS) &amp; Peripheral Nervous System (PNS)</p> Signup and view all the answers

    What are neuroglia cells?

    <p>Non-neuronal cells that support the functioning of neurons</p> Signup and view all the answers

    Match the glial cells with their functions:

    <p>Satellite cells = Surround neuron cell bodies in ganglia. Regulate O2 and CO2, nutrient, and neurotransmitter levels around the neurons in ganglia Schwann cells = Surround axons in PNS, responsible for myelination of peripheral axons, participate in the repair process after injury Oligodendrocytes = Myelinate CNS axons, provide structural framework Astrocytes = Maintain blood-brain barrier, provide structural support, regulate ion, nutrient and dissolved gas concentrations, absorb and recycle neurotransmitters, form scar tissue after injury Ependymal cells = Line ventricles (brain) and central canal (spinal cord) and assist in producing, circulating, and monitoring CSF Microglia = Remove cell debris, wastes and pathogens by phagocytosis</p> Signup and view all the answers

    What type of glial cell is responsible for producing cerebrospinal fluid?

    <p>Ependymal cells</p> Signup and view all the answers

    What two glial cells are found in the Peripheral Nervous System?

    <p>Schwann cells and Satellite cells</p> Signup and view all the answers

    What 4 glial cells are found in the central nervous system?

    <p>Astrocytes, Oligodendrocytes, Microglia, and Ependymal cells</p> Signup and view all the answers

    Which glial cells are responsible for myelination around the axon?

    <p>Oligodendrocytes and Schwann</p> Signup and view all the answers

    Which glial cell acts as a macrophage?

    <p>Microglia</p> Signup and view all the answers

    Where are sodium ions found? Outside or Inside the cell?

    <p>Outside the cell</p> Signup and view all the answers

    Where are potassium ions typically found in a cell?

    <p>Inside the cell</p> Signup and view all the answers

    What is the resting potential of neurons?

    <p>-70mV</p> Signup and view all the answers

    Why do neurons have a resting potential of -70mV?

    <p>Because of the difference in ion concentrations found in the inside and outside of the cell</p> Signup and view all the answers

    How do messages within the neuron travel?

    <p>Along the length of the axon through electrical impulses</p> Signup and view all the answers

    How does the message BETWEEN neurons travel?

    <p>Through the release of neurotransmitters (chemically)</p> Signup and view all the answers

    As the action potential travels down the axon, it gets picked up by what voltage-gated channel?

    <p>Calcium</p> Signup and view all the answers

    What are the 5 steps in the process of neurotransmitters being released onto neurons?

    <ol> <li>Action potential depolarizes the axon terminal</li> <li>The depolarization opens voltage-gated Ca2 channels and Ca2 enters the cell</li> <li>Calcium entry triggers exocytosis of synaptic vesicle contents</li> <li>Neurotransmitter diffuses across the synaptic cleft and binds with receptors on the postsynaptic cell</li> <li>Neurotransmitter binding initiates a response in the postsynaptic cell</li> </ol> Signup and view all the answers

    What are the two neurotransmitters that are amino acids?

    <p>Glutamate and GABA</p> Signup and view all the answers

    What are the four main types of nervous system ion channels?

    <p>Ligand-gated, Mechanically-gated, Always Open, and Voltage gated</p> Signup and view all the answers

    Match the type of ion channel with its characteristic:

    <p>Chemically gated = Opened by neurotransmitters Mechanically gated = Open in response to physical force Always open = Potassium channels Voltage-gated = Respond to electrical signals</p> Signup and view all the answers

    Match the characteristics with the type of potential:

    <p>Variable strength = Graded potential Constant strength = Action potential Can sum to cause an action potential = Graded potential All or none = Action potential Generated at axon hillock = Action potential Does not travel through the neuron = Graded potential Travels from dendrites to axon terminal = Action potential Intensity of stimulus coded in frequency of potentials = Action potential</p> Signup and view all the answers

    What are the two types of graded potential?

    <p>Excitatory postsynaptic potential (EPSP) and inhibitory postsynaptic potential (IPSP)</p> Signup and view all the answers

    What is the difference between temporal summation and spatial summation?

    <p>Temporal summation occurs when multiple neurons stimulate a single neuron at the same time, while spatial summation occurs when a single neuron is stimulated by multiple neurons at different times.</p> Signup and view all the answers

    Match the stages of an action potential with their corresponding descriptions:

    <ol> <li>Resting potential = Sodium-potassium pump (Na+/K+) maintains electrochemical gradient. Some K+ leaks out of the neuron</li> <li>Depolarization = Voltage gated Na+ channel open. Sodium enters neuron by diffusion. Membrane potential is achieved (threshold potential)</li> <li>Repolarization = Voltage gated K+ channel open. K+ exits out of the neuron causing membrane potential to be negative again</li> <li>Resting potential (reset) = Distribution of Na+/K+ is reset by returning the neuron to resting potential</li> </ol> Signup and view all the answers

    How does the sodium-potassium pump work?

    <p>It pumps sodium ions out of the cell and potassium ions into the cell by active transport</p> Signup and view all the answers

    What is the result of the balance of ion concentration on both sides of the membrane?

    <p>2 K+ are released and 3 Na+ enter the cell</p> Signup and view all the answers

    Match the type of conduction with its characteristics:

    <p>Continues Conduction = Action potential travels entire length of an axon, occurs in unmyelinated axons, travels about 1 m/Sec Saltatory Conduction = Action potential only propagated at node of Ranvier, occurs in myelinated axons, travels about 100 m/sec</p> Signup and view all the answers

    What is the mechanism of saltatory conduction in myelinated axons?

    <p>The influx of Na+ ions causes the displacement of K+ ions down the axon.</p> Signup and view all the answers

    How does an electrical signal jump from node to node in an axon?

    <p>By saltatory conduction via the Node of Ranvier</p> Signup and view all the answers

    What is the relationship between stimulus intensity and frequency of action potentials?

    <p>A stronger stimulus results in a higher frequency of action potentials</p> Signup and view all the answers

    How is the strength of a stimulus coded?

    <p>By the frequency of action potentials</p> Signup and view all the answers

    What is the primary location of Cerebral Spinal Fluid (CSF) formation?

    <p>Choroid Plexus</p> Signup and view all the answers

    What are the main functions of CSF?

    <p>Physical support and protection</p> Signup and view all the answers

    Match the following brain structures with their respective functions:

    <p>Cerebral Cortex = Ultimate control and information processing center Corpus Callosum = Axon fibers connecting two cerebral hemispheres Fornix = Acts as the major output tract of the hippocampus Hippocampus = Linked to memory Amygdala = Linked to emotion Cerebellum = Coordinates voluntary movement and balance and supports memories of such Medulla oblongata = Helps regulate breathing, heart, and blood and vessel function Spinal Cord = Pathway to neural fibers, traveling to and from brain, controls simple reflexes Pons = Involved in the control of breathing sensations, such as hearing, taste, and balance Midbrain = Motor movement, particularly movements of the eye and in auditory and visual processing Pituitary = Master endocrine gland Hypothalamus = Controls maintenance functions like eating, helps govern endocrine system, linked to emotion and reward</p> Signup and view all the answers

    Match the characteristics with the correct type of memory:

    <p>Holds 7 to 12 pieces of information = Short-term memory Disappears if not reinforced = Short-term memory Holds vast amount of information = Long-term memory Converted from short-term memory by a process called consolidation = Long-term memory</p> Signup and view all the answers

    What are the targets of the Autonomic Nervous System (ANS)?

    <p>Smooth muscle, cardiac muscle, and glands</p> Signup and view all the answers

    What are the two neurons found in the Autonomic Nervous System (ANS)?

    <p>Preganglionic neuron and postganglionic neuron</p> Signup and view all the answers

    Preganglionic neurons release what type of neurotransmitter?

    <p>Acetylcholine</p> Signup and view all the answers

    What does the parasympathetic system release?

    <p>Acetylcholine</p> Signup and view all the answers

    What does the sympathetic system release?

    <p>Epiniephrine</p> Signup and view all the answers

    What happens to major organs when influenced by the sympathetic nervous system?

    <p>They increase their activity</p> Signup and view all the answers

    What does the most stimulated sensory neuron do to its surrounding neighbors?

    <p>Inhibit them</p> Signup and view all the answers

    What type of stimulus corresponds to tonic receptors?

    <p>little adaptation, constant firing of action potentials. examples stretch receptors, pain receptors, photoreceptors, mechanoreceptors</p> Signup and view all the answers

    What type of stimuli belong to phasic receptors?

    <p>Transient or changing stimuli, such as smell, pressure, and touch</p> Signup and view all the answers

    What is the primary function of special sensory receptors?

    <p>To release neurotransmitters onto sensory neurons</p> Signup and view all the answers

    What property of stimuli determines the type of environmental stimuli sensed by neurons?

    <p>Modality</p> Signup and view all the answers

    Which type of sensory receptor responds to change in temperature?

    <p>Thermoreceptors</p> Signup and view all the answers

    What is the term for the capacity of an excited neuron to reduce the activity of its neighbors?

    <p>Lateral inhibition</p> Signup and view all the answers

    What type of sensory receptor responds to tissue damage?

    <p>Nociceptors</p> Signup and view all the answers

    What is the term for the physiological capacity of an organism to acquire data for a perception?

    <p>Sense</p> Signup and view all the answers

    Which type of sensory receptor monitors internal systems such as the digestive and respiratory systems?

    <p>Interceptors</p> Signup and view all the answers

    What determines the type of sensation evoked by a particular stimulus?

    <p>Modality of the stimulus</p> Signup and view all the answers

    What is the role of DHP channels in skeletal muscles?

    <p>To act as a voltage sensor and activate RYR channels</p> Signup and view all the answers

    What is the result of calcium binding to troponin during muscle contraction?

    <p>Tropomyosin is pulled away, exposing the binding sites on actin</p> Signup and view all the answers

    What is the function of acetylcholinesterase in muscle relaxation?

    <p>To break down acetylcholine in the synapse</p> Signup and view all the answers

    What structure brings the action potential to the surface of the muscle fiber?

    <p>T-tubules</p> Signup and view all the answers

    What is the result of tropomyosin moving back to cover the binding sites on actin during muscle relaxation?

    <p>The muscle relaxes and returns to its resting state</p> Signup and view all the answers

    What is found in the sarcoplasmic reticulum that is responsible for releasing calcium ions?

    <p>RYR receptors</p> Signup and view all the answers

    What is the purpose of lateral inhibition in the nervous system?

    <p>To sharpen contrast between activated receptor fields and their inactive neighbors</p> Signup and view all the answers

    How is the strength of a stimulus coded in sensory neurons?

    <p>By the frequency of action potentials</p> Signup and view all the answers

    What is the characteristic of tonic receptors?

    <p>They show little adaptation</p> Signup and view all the answers

    What is the purpose of receptor adaptation?

    <p>To decrease the sensitivity of a receptor</p> Signup and view all the answers

    What is the effect of the sympathetic nervous system on the heart?

    <p>It increases the heart rate</p> Signup and view all the answers

    What is the neurotransmitter released by the sympathetic nervous system?

    <p>Norepinephrine</p> Signup and view all the answers

    What is the function of varicosities in the nervous system?

    <p>They are the sites of neurotransmitter synthesis, storage, and release</p> Signup and view all the answers

    How do skeletal muscles work?

    <p>In antagonistic pairs</p> Signup and view all the answers

    What is the function of the motor unit in skeletal muscle physiology?

    <p>It is the motor neuron and all muscle fibers it innervates</p> Signup and view all the answers

    What is the role of acetylcholine in muscle contraction?

    <p>It triggers muscle contraction</p> Signup and view all the answers

    Study Notes

    Structural Types of Sensory Receptors

    • Simple sensory receptors: neurons with free nerve endings (e.g., pain, tickle, itch, temperature)
    • Complex sensory receptors: nerve endings enclosed in connective tissue capsules (e.g., touch, pressure, vibration)
    • Special sensory receptors: cells that release neurotransmitters onto sensory neurons (e.g., vision, hearing, taste, smell)

    Properties of Stimuli

    • Modality: the type of environmental stimuli sensed by neurons
    • Location: where the stimulus is detected (e.g., interoceptors, exteroceptors, proprioceptors)
    • Intensity: the strength of the stimulus (coded by frequency of action potentials)
    • Duration: the length of time the stimulus is present (influenced by receptor adaptation)

    Receptor Adaptation

    • Two types of receptors: tonic receptors (little adaptation) and phasic receptors (decreased firing of action potentials)
    • Examples of tonic receptors: stretch receptors, pain receptors, photoreceptors, mechanoreceptors
    • Examples of phasic receptors: smell, pressure, touch, temperature

    Autonomic Nervous System (ANS)

    • Two-neuron chain from CNS to effector organs
    • Neurotransmitters: norepinephrine (sympathetic pathway), acetylcholine (parasympathetic pathway)
    • Effects of dual innervation:
      • Parasympathetic nerves (rest and digest): constrict pupils, stimulate saliva, slow heartbeat, etc.
      • Sympathetic nerves (fight or flight): dilate pupils, inhibit salivation, increase heartbeat, etc.

    Varicosities

    • Beads that line branches of postganglionic neurons, sites of neurotransmitter synthesis, storage, and release

    Skeletal Muscle Physiology

    • Antagonistic pairs: flexors and extensors work together to allow force in opposite directions
    • Motor unit: motor neuron and all muscle fibers it innervates
    • Action potential, sarcolemma generation, and muscle contraction:
      • Action potential travels through axon and reaches synaptic terminal
      • Calcium flow allows vesicles to fuse with plasma membrane, releasing acetylcholine
      • Acetylcholine binds to receptors on sarcolemma, triggering muscle action potentials
      • Action potential propagates across sarcolemma and travels into T-tubules
      • DHP channels are activated, releasing calcium from sarcoplasmic reticulum
      • Calcium binds to troponin, exposing binding sites on actin
    • Muscle contraction:
      • Calcium is released from SR and diffuses across the cytoplasm
      • Calcium binds to troponin, allowing muscle contraction
    • Muscle relaxation:
      • Acetylcholinesterase decomposes acetylcholine in the synapse
      • Calcium is actively pumped back into SR
      • Tropomyosin moves back to cover binding sites, and myosin head detaches

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