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Questions and Answers
What is the primary function of the blood-brain barrier?
What is the primary function of the blood-brain barrier?
How many steps are involved in the process of sensation?
How many steps are involved in the process of sensation?
Which type of imaging is specifically designed to measure brain function?
Which type of imaging is specifically designed to measure brain function?
What sensory modalities are detected by nociceptors?
What sensory modalities are detected by nociceptors?
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Which structure is responsible for regulating body temperature and other homeostatic functions?
Which structure is responsible for regulating body temperature and other homeostatic functions?
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What do stretch reflexes primarily function to maintain?
What do stretch reflexes primarily function to maintain?
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How does the density of receptive fields affect sensory localization?
How does the density of receptive fields affect sensory localization?
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What type of receptor responds to changes in temperature?
What type of receptor responds to changes in temperature?
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What is the primary function of the iris in the visual system?
What is the primary function of the iris in the visual system?
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Which photoreceptors are concentrated in the fovea, contributing to its high visual acuity?
Which photoreceptors are concentrated in the fovea, contributing to its high visual acuity?
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What is the first structure that sound waves vibrate upon entering the ear?
What is the first structure that sound waves vibrate upon entering the ear?
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What type of muscle fibers are characterized by striations?
What type of muscle fibers are characterized by striations?
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Which system is responsible for the fight-or-flight response?
Which system is responsible for the fight-or-flight response?
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How do agonists affect neurotransmitter receptors?
How do agonists affect neurotransmitter receptors?
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What does electromyography (EMG) measure?
What does electromyography (EMG) measure?
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Which of the following structures is NOT typically involved in the auditory pathway?
Which of the following structures is NOT typically involved in the auditory pathway?
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Which component is primarily responsible for initiating muscle contraction?
Which component is primarily responsible for initiating muscle contraction?
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What is the role of the SERCA pumps in muscle contraction?
What is the role of the SERCA pumps in muscle contraction?
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What would likely occur if voltage-gated Ca2+ channels are blocked?
What would likely occur if voltage-gated Ca2+ channels are blocked?
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Which muscle fiber type is characterized by striations and involuntary control?
Which muscle fiber type is characterized by striations and involuntary control?
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How does the presence of tropomyosin affect muscle contraction?
How does the presence of tropomyosin affect muscle contraction?
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What process allows muscle fibers to generate more force during contraction?
What process allows muscle fibers to generate more force during contraction?
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Which structure carries the action potential deep into the muscle fiber?
Which structure carries the action potential deep into the muscle fiber?
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Which component does not directly participate in the contraction cycle?
Which component does not directly participate in the contraction cycle?
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What role does troponin play in muscle contraction?
What role does troponin play in muscle contraction?
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In which type of muscle is the contraction primarily voluntary?
In which type of muscle is the contraction primarily voluntary?
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Study Notes
Nervous System
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Divisions
- Central Nervous System (CNS): brain and spinal cord
- Peripheral Nervous System (PNS): nerves extending from the CNS
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Brain Protection
- Cranium: bony structure of the skull
- Meninges: three layers of protective tissues surrounding the brain and spinal cord
- Cerebrospinal Fluid: cushions the brain and spinal cord, provides nutrients, and removes waste
- Blood-Brain Barrier: selective barrier that controls the passage of substances from blood vessels into brain tissue
- Blood-Brain Barrier Impact: restricts the passage of many drugs and other substances, protecting the brain from harmful toxins and pathogens
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Cerebrum Organization
- Cerebral Cortex: outer layer responsible for higher cognitive functions
- Brodmann Areas: numbered regions of the cerebral cortex with distinct structural and functional characteristics
- Motor Cortex: controls voluntary movement
- Somatosensory Cortex: receives sensory information from the body
- Auditory Cortex: processes sound information
- Visual Cortex: processes visual information
- Facial Recognition Area: specialized area for recognizing faces
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Hypothalamus
- Regulates basic homeostatic functions like temperature, hunger, thirst, and sleep-wake cycles
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Cerebellum
- Coordinates movement, balance, and posture
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Brain Structure & Function Measurement
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Structure
- MRI: magnetic resonance imaging, provides detailed images of brain structures
- CT: computed tomography, creates cross-sectional images of the brain
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Function
- fMRI: functional MRI, measures brain activity by detecting changes in blood flow
- EEG: electroencephalography, records electrical activity in the brain
- PET: positron emission tomography, measures brain activity by detecting the distribution of radioactive tracers
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Structure
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Sensory Receptors
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Categories:
- Peripheral Endings: specialized endings of nerve fibers, like pain receptors
- Separate Cells: specialized cells that communicate with nerve fibers, like photoreceptor cells in the eye
- Signal Transduction: sensory receptors convert stimuli into electrical signals that can be interpreted by the nervous system
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Categories:
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Sensation
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Steps:
- Stimulation of the Sensory Receptor: the sensory receptor is exposed to the stimulus
- Transduction of the Stimulus: the sensory receptor converts the stimulus into a change in membrane potential
- Generation of Action Potentials: if the stimulus is strong enough, the receptor generates action potentials that travel along the neuron
- Integration of Sensory Input: the brain processes and interprets the sensory information
- Receptive Field: the area of the body that, when stimulated, activates a particular sensory neuron
- Receptive Field Density and Overlap: determine the ability to discriminate between stimuli
- Stimulus Intensity and Duration Coding: frequency and duration of action potentials convey information about the intensity and duration of the stimulus
- Adaptation: a decrease in the response of a sensory receptor to a constant stimulus
- Sensory Modality: the type of stimulus that is detected (e.g., light, sound, touch)
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Steps:
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Somatic Sensations: sensory information from the skin, muscles, joints, and tendons
- Tactile Sensations: touch, pressure, vibration
- Thermal Sensations: temperature (hot and cold receptors)
- Pain Sensations: nociceptors detect tissue damage
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Proprioceptive Sensations: position and movement of the body
- Stretch Reflex: protects muscles from overstretching
- Tendon Organ Reflex: protects tendons from excessive tension
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Olfactory System: sense of smell
- Fast-adapting: sensitivity to an odor decreases rapidly after exposure
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Gustatory System: sense of taste
- Not as sensitive as olfaction: limited number of taste receptors
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Visual System
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Light Path:
- Pupil: opening in the iris that allows light to enter the eye
- Iris: controls the size of the pupil to adjust the amount of light entering the eye
- Lens: focuses light on photoreceptor cells in the retina
- Retina: light-sensitive layer at the back of the eye containing photoreceptors
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Photoreceptors:
- Rods: sensitive to low levels of light, responsible for night vision
- Cones: require higher levels of light, responsible for color vision
- Fovea: the central region of the retina with the highest density of cones, responsible for sharp, central vision
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Fovea Central Vision:
- high density of cones
- direct connection between cones and ganglion cells
- absence of blood vessels
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Sensory Information Pathway:
- Retina
- Optic Nerve
- Optic Chiasm: where fibers from the nasal halves of each eye cross
- Optic Tract
- Lateral Geniculate Nucleus (thalamus)
- Visual Cortex (occipital lobe)
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Light Path:
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Auditory and Vestibular Systems
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Sound Wave Transduction:
- Tympanic Membrane: vibrates in response to sound waves
- Ossicles: three small bones in the middle ear that amplify sound vibrations
- Cochlear Fluids: fluid-filled chambers in the inner ear
- Basilar Membrane: flexible membrane within the cochlea, different frequencies cause specific parts of the membrane to vibrate
- Hair Cells: sensory receptors on the basilar membrane, movement of hair cells triggers nerve impulses
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Sound Wave Transduction:
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Sound Localization:
- External Ear: captures sound waves
- Middle Ear: amplifies sound vibrations
- Inner Ear: contains the cochlea and the vestibular apparatus, responsible for hearing and balance
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Vestibular System
- Otolithic Organs: detect linear acceleration and head position
- Semicircular Canals: detect rotational movement
- Hair Cell Motion: movement of hair cells in the vestibular apparatus triggers nerve impulses that inform the brain about head movement and position.
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Autonomic Nervous System
- Regulates: involuntary functions like heartbeat, digestion, respiration, and body temperature
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Divisions:
- Sympathetic Nervous System: "fight-or-flight" response, prepares the body for action
- Parasympathetic Nervous System: rest-and-digest response, conserves energy and promotes relaxation
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Neurotransmitters:
- Sympathetic: mostly uses norepinephrine (NE) and epinephrine (E)
- Parasympathetic: mostly uses acetylcholine (ACh)
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Agonists and Antagonists:
- Agonists: mimic the effects of neurotransmitters
- Antagonists: block the effects of neurotransmitters
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Somatic Nervous System
- Controls: voluntary movement
- Neuromuscular Junction: where a motor neuron synapses with a muscle fiber
- Neurotransmitter: acetylcholine (ACh)
- End Plate Potential (EPP): a depolarization of the muscle fiber membrane caused by ACh release
- Muscle Action Potential: if the EPP is strong enough, it triggers an action potential in the muscle fiber, leading to muscle contraction
- Electromyography (EMG): a technique for measuring and recording the electrical activity of muscles
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Skeletal Muscle
- Striations: stripes seen in skeletal muscle fibers under a microscope, due to the arrangement of actin and myosin filaments
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Types:
- Type I (Slow Oxidative): slow-twitch, high endurance, red in color due to rich blood supply
- Type IIa (Fast Oxidative Glycolytic): fast-twitch, moderate endurance, pink in color
- Type IIb (Fast Glycolytic): fast-twitch, low endurance, white in color
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Contraction Cycle: the series of events that lead to muscle contraction, involving the interaction of actin and myosin filaments
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Roles:
- Myosin: thick filament, contains myosin heads that bind to actin filaments
- Actin: thin filament, contains binding sites for myosin heads
- ATP: provides energy for the contraction cycle
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Roles:
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Cardiac Muscle
- Found only in the heart
- Striated
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Unique Features:
- Intercalated Discs: specialized junctions that connect cardiac muscle cells, allowing for rapid communication and coordinated contraction
- Autorhythmic: can generate its own rhythm
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Smooth Muscle
- Found in the walls of internal organs (e.g., stomach, intestines)
- Non-striated
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Types:
- Visceral Smooth Muscle: found in the walls of hollow organs
- Multi-Unit Smooth Muscle: found in the iris of the eye and walls of blood vessels
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Excitation-Contraction Coupling
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Steps:
- Action Potential: an action potential travels along the muscle fiber membrane
- T-Tubule: the action potential travels into the muscle fiber through T-tubules, small invaginations of the sarcolemma (cell membrane)
- Voltage-Gated Ca2+ Channels: opening of voltage-gated calcium channels in the T-tubules
- Sarcoplasmic Reticulum: release of calcium ions (Ca2+) from the sarcoplasmic reticulum (SR), a specialized organelle that stores calcium within the muscle fiber
- Ca2+ Binding to Troponin: calcium ions bind to troponin, a protein located on actin filaments
- Tropomyosin Movement: binding of calcium to troponin causes tropomyosin, another protein on actin filaments, to move away from the myosin-binding sites on actin
- Cross-Bridge Formation: myosin heads bind to actin, forming cross-bridges
- Power Stroke: myosin heads pivot, pulling actin filaments toward the center of the sarcomere (the functional unit of a muscle fiber)
- ATP Binding: ATP binds to myosin heads, causing them to detach from actin
- Re-energize Myosin: ATP is hydrolyzed, providing energy to re-energize the myosin heads and allow them to bind to actin again
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Components:
- Muscle fiber: the individual cell of a muscle
- T-Tubule: helps spread the action potential into the interior of the muscle fiber
- Voltage-gated Ca2+ channels: open in response to the action potential, allowing calcium into the muscle fiber
- Sarcoplasmic reticulum: stores and releases calcium
- Myofibril: contains the contractile proteins, actin and myosin, that make up the muscle fiber
- Sarcomere: the basic unit of muscle contraction
- Actin filament: thin filament, has binding sites for myosin heads
- Myosin filament: thick filament, contains myosin heads that bind to actin
- Myosin heads: bind to actin and pull the filaments together, causing muscle contraction
- Troponin: a protein that regulates the interaction of actin and myosin
- Tropomyosin: a ribbon-like protein that blocks myosin-binding sites on actin in the relaxed state
- SERCA pumps: pumps calcium back into the SR, allowing muscle relaxation
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Steps:
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Motor Unit Recruitment
- Motor Unit: a motor neuron and all the muscle fibers it innervates
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Recruitment: as the force needed to perform a task increases, the nervous system recruits more motor units to create a stronger contraction
- Smaller motor units are recruited first, followed by larger motor units
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Summation
- Temporal Summation: increasing the frequency of stimulation of a single motor unit, leading to a stronger contraction.
- Spatial Summation: increasing the number of motor units that are activated, resulting in a stronger contraction.
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Description
Test your knowledge on the divisions of the nervous system, including the Central and Peripheral Nervous Systems. Explore the protective structures for the brain and spinal cord, such as the cranium and meninges, and understand the importance of the blood-brain barrier. This quiz covers key concepts related to brain organization and function.
