Podcast
Questions and Answers
What electrolyte is critically involved in neurotransmitter release from synaptic bulbs?
What electrolyte is critically involved in neurotransmitter release from synaptic bulbs?
Which of the following is NOT a mechanism for terminating synaptic transmission?
Which of the following is NOT a mechanism for terminating synaptic transmission?
Which component of the brainstem is responsible for regulating vital functions such as heart rate and breathing?
Which component of the brainstem is responsible for regulating vital functions such as heart rate and breathing?
What is the primary feature that distinguishes contralateral control from ipsilateral control in the brain?
What is the primary feature that distinguishes contralateral control from ipsilateral control in the brain?
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What condition occurs when there is a disruption in the normal flow of cerebrospinal fluid?
What condition occurs when there is a disruption in the normal flow of cerebrospinal fluid?
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Which part of the diencephalon is involved in regulating body temperature and hunger?
Which part of the diencephalon is involved in regulating body temperature and hunger?
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What is the primary difference between Broca's Aphasia and Wernicke's Aphasia?
What is the primary difference between Broca's Aphasia and Wernicke's Aphasia?
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What is the role of the threshold in generating an action potential?
What is the role of the threshold in generating an action potential?
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What effect does severe loss of body calcium have on the nervous system?
What effect does severe loss of body calcium have on the nervous system?
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Which of the following neuroglial cells is responsible for producing myelin in the central nervous system?
Which of the following neuroglial cells is responsible for producing myelin in the central nervous system?
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Which statement is true regarding the PNS?
Which statement is true regarding the PNS?
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What happens during the repolarization phase of an action potential?
What happens during the repolarization phase of an action potential?
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Which mechanism contributes to setting the resting membrane potential at -70mV?
Which mechanism contributes to setting the resting membrane potential at -70mV?
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How do myelin and the nodes of Ranvier influence action potential speed?
How do myelin and the nodes of Ranvier influence action potential speed?
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Which of the following best describes graded potentials?
Which of the following best describes graded potentials?
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What is the primary function of the Na+/K+ pump?
What is the primary function of the Na+/K+ pump?
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Study Notes
Nervous System Functions & Divisions
- The nervous system's main functions are:
- Sensory input: Gathering information from the environment
- Integration: Processing and interpreting sensory information
- Motor output: Sending signals to muscles and glands to produce responses
- Central nervous system (CNS) handles integration
- Peripheral nervous system (PNS) handles sensory input and motor output
CNS and PNS Organs
- CNS components: Brain and spinal cord
- PNS components: All nerves outside the brain and spinal cord
PNS Subdivisions
- Autonomic nervous system: Regulates involuntary body functions like heart rate, digestion, and breathing
- Somatic nervous system: Controls voluntary movement of skeletal muscles
Neuroglial Cells
- Astrocyte: Star-shaped, provides structural support, regulates blood flow, and maintains chemical environment for neurons
- Ependymal cell: Lines cavities of brain and spinal cord, produces cerebrospinal fluid (CSF)
- Microglial cell: Phagocytic cells that engulf cellular debris and pathogens
- Oligodendrocyte: Forms myelin sheath around axons in the CNS, increasing conduction speed
- Satellite cell: Surrounds neuron cell bodies in the PNS, providing support and regulation
- Schwann cell: Forms myelin sheath around axons in the PNS, increasing conduction speed
Neuronal Transport Proteins
- Leak channel: Allows ions to move passively down their concentration gradient, important for maintaining resting membrane potential
- Voltage-gated channel: Opens in response to changes in membrane potential, involved in action potential propagation
- Ligand-gated channel: Opens in response to binding of a specific neurotransmitter, involved in synaptic transmission
- Na+/K+ pump: Actively transports 3 sodium ions out of the cell and 2 potassium ions into the cell, maintaining the concentration gradients that drive membrane potential
Neuron Functions
- Neuron functions include:
- Receive signals
- Integrate information
- Transmit signals
Components of a Neuron
- Dendrite: Receives signals from other neurons
- Axon hillock: Region where the action potential is generated
- Axon: Transmits signals away from the cell body
- Synaptic bulb: Terminal end of the axon where neurotransmitters are released
Threshold and Action Potential
- Threshold: Minimal level of depolarization required to trigger an action potential
- All-or-none principle: An action potential either fires completely or not at all, depending on whether threshold is reached
Myelin and Nodes of Ranvier
- Myelin: Fatty insulating sheath around axons, increasing conduction speed by preventing ion leakage
- Nodes of Ranvier: Gaps in the myelin sheath where action potentials are regenerated, allowing for rapid signal transmission
Action Potential Generation
- Depolarization: Sodium ions rush into the cell through voltage-gated sodium channels, making the inside of the cell more positive
- Repolarization: Potassium ions flow out of the cell through voltage-gated potassium channels, making the inside of the cell more negative
- Hyperpolarization: The membrane potential becomes even more negative than the resting membrane potential, due to continued potassium outflow
- Return to resting membrane potential (RMP): Sodium-potassium pump restores the original ion concentrations, restoring the resting membrane potential
Graded Potentials
- Graded potential: Localized, short-lived change in membrane potential, can be depolarizing or hyperpolarizing
- Hyperpolarizing graded potential: Makes the membrane potential more negative, decreasing the likelihood of an action potential
- Depolarizing graded potential: Makes the membrane potential less negative, increasing the likelihood of an action potential
Resting Membrane Potential (RMP)
- RMP is set by two mechanisms:
- Unequal distribution of ions across the membrane
- Sodium-potassium pump
Refractory Period
- Refactory period: Time period following an action potential during which a neuron is less likely to generate another action potential
- This prevents the action potential from traveling backward along the axon
Signal Strength
- A neuron signals increased stimulus strength by:
- Increasing the frequency of action potentials
- Recruiting more neurons
Multiple Sclerosis
- Cause: Autoimmune disease that destroys myelin sheath in the CNS
- Outcome: Disrupts action potential propagation, leading to muscle weakness, fatigue, and other neurological symptoms
Myelin and Axon Diameter
- Myelin increases conduction speed, as does a larger axon diameter
- Larger axons have less resistance to current flow, allowing for faster action potential propagation
Neuron Groups
- Group A neurons: Largest diameter and myelinated, fastest conduction speed, found in sensory and motor pathways
- Group B neurons: Intermediate diameter and myelinated, intermediate conduction speed, found in autonomic nervous system
- Group C neurons: Smallest diameter and unmyelinated, slowest conduction speed, found in autonomic nervous system
Synaptic Transmission
- Goals: Transmission of an action potential from one neuron to another
- Process:
- Action potential arrives at the synaptic bulb
- Calcium ions enter the synaptic bulb through voltage-gated calcium channels
- Calcium triggers the release of neurotransmitters from synaptic vesicles
- Neurotransmitters diffuse across the synaptic cleft and bind to receptors on the postsynaptic neuron
- Binding of neurotransmitters triggers a response in the postsynaptic neuron
- Type of transport: Exocytosis
Calcium and Neurotransmitter Release
- Calcium is responsible for neurotransmitter release from synaptic bulbs
- Severe loss of body calcium can lead to coma due to a decrease in neurotransmitter release, disrupting brain function
Termination of Synaptic Transmission
- 3 mechanisms for terminating synaptic transmission:
- Reuptake of neurotransmitters by presynaptic neurons
- Enzymatic degradation of neurotransmitters in the synaptic cleft
- Diffusion of neurotransmitters away from the synaptic cleft
EPSP and IPSP
- Excitatory postsynaptic potential (EPSP): Depolarizing graded potential that increases the likelihood of an action potential in the postsynaptic neuron
- Inhibitory postsynaptic potential (IPSP): Hyperpolarizing graded potential that decreases the likelihood of an action potential in the postsynaptic neuron
Brainstem Components
- Medulla oblongata: Controls vital functions like breathing, heart rate, and blood pressure
- Pons: Relays signals between the cerebrum and cerebellum, involved in sleep and respiration
- Midbrain: Controls eye movement, auditory and visual reflexes
Parkinson's Disease
- Cause: Degeneration of dopaminergic neurons in the substantia nigra, a region of the midbrain
- Patient outcomes: Muscle rigidity, tremors, and slow movements
Diencephalon Components
- Thalamus: Relays sensory information to the cerebrum, filters and relays signals
- Hypothalamus: Regulates autonomic functions, controls hormone release, and influences emotions
- Epithalamus (Pineal gland): Secretes melatonin, regulating sleep-wake cycles
Hypothalamic Tumors
- Patient outcomes: Can affect hormonal balance, leading to various symptoms like weight changes, altered sleep patterns, and emotional disturbances
Contralateral & Ipsilateral Control
- Contralateral control: One side of the brain controls movements on the opposite side of the body, typical for motor pathways
- Ipsilateral control: One side of the brain controls movements on the same side of the body, seen in some motor pathways
Cerebrum Lobes
- Frontal lobe: Responsible for higher-level cognitive functions, planning, decision-making, and motor control
- Parietal lobe: Processes sensory information, including touch, temperature, pain, and pressure
- Occipital lobe: Responsible for vision
- Temporal lobe: Processes auditory information, memory, and language
- Insula: Involved in taste, pain, and visceral sensations
Broca's and Wernicke's Aphasia
- Broca's aphasia: Difficulty producing speech, often speaking with a telegraphic style
- Wernicke's aphasia: Difficulty understanding language, speaking fluently but often with irrelevant or nonsensical words
Cerebellum Function
- Cerebellum: Coordinates and refines movements, controls balance and posture
Neuroendocrine Structures
- Hypothalamus: Secretes hormones like antidiuretic hormone (ADH) and oxytocin
- Pineal gland: Secretes melatonin
Meninges and Cerebrospinal Fluid (CSF)
- Meninges: Protective membranes that surround the brain and spinal cord
- Dura mater: Outermost layer, tough and fibrous
- Arachnoid mater: Middle layer, web-like
- Pia mater: Innermost layer, delicate and adheres to the brain and spinal cord
- Cerebrospinal fluid (CSF): Clear fluid that circulates around the brain and spinal cord, providing cushioning and removing waste products
- CSF is produced by choroid plexuses in the ventricles of the brain
Cauda Equina and Epidural Space
- Cauda equina: Bundle of spinal nerves that extend from the end of the spinal cord, resembling a horse's tail
- Epidural space: Space between the dura mater and the vertebral canal, containing fat and blood vessels
Spinal Cord Injuries
- Damage to dorsal, ventral, or lateral horns: Can result in loss of sensory, motor, or autonomic functions
- Damage to dorsal or ventral root: Can result in loss of sensory or motor function, respectively
- Spinal nerve injury: Can result in loss of both sensory and motor function
Neurological Terms
- Paralysis: Loss of muscle function
- Parathesias: Abnormal sensations, such as tingling or numbness
- Paraplegia: Paralysis of the lower limbs
- Quadriplegia: Paralysis of all four limbs
- Hemiplegia: Paralysis of one side of the body
Spinal Cord Diseases
- Spina bifida: Congenital defect where the spinal cord does not close properly
- Amyotrophic lateral sclerosis (ALS): Degenerative disease that affects motor neurons, leading to muscle weakness and paralysis
Concert Scenario
- The pressure of the girl's shoe is detected by mechanoreceptors in the big toe, sending this sensory information to the spinal cord via sensory neurons
- The spinal cord relays the signal to the brain, where it is processed in the somatosensory cortex
- The brain then sends a motor signal back down the spinal cord via motor neurons to the muscles of the leg to withdraw the foot
- This reflex arc allows for a quick response to the painful stimulus before you even consciously perceive the pain
- You probably feel the pain a few milliseconds later as the signal travels along the slower, longer pathway to the brain for more complex processing
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Description
Explore the essential functions and divisions of the nervous system in this quiz. Learn about the roles of the central nervous system (CNS) and peripheral nervous system (PNS), including their various components and subdivisions. Test your knowledge on neuroglial cells and their functions as well.
