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Questions and Answers
Which part of the auditory pathway comes after the cochlear nuclei in the medulla oblongata and pons?
What is conduction deafness primarily caused by?
Which statement is true about sensorineural deafness?
What best describes presbycusis?
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Which type of nerve endings are responsible for detecting pain, cold, and heat sensations?
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What type of sensory receptors are Merkel’s disks?
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What is NOT a potential cause of conduction deafness?
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Which type of receptor is a Pacinian corpuscle?
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Which structures are involved in the taste pathway?
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What replaces damaged olfactory receptors in the nasal cavity?
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What is a key function of the G-protein in the smell process?
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How many G-proteins may be associated with one olfactory receptor protein?
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What do cAMP and PPi activate in the smell signal transduction pathway?
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Where are the olfactory receptors located?
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Which of the following structures is NOT involved in the taste pathway?
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What is the main function of the primary gustatory cortex?
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What is the role of adenylate cyclase in the process of odor binding?
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Which ion channels are opened by cAMP during the olfactory response?
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How does odor binding contribute to sensory sensitivity?
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Where do mitral and tufted neurons from the olfactory bulb synapse?
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Which brain structures are interconnected with the olfactory system?
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Which brain structures receive input from the mitral and tufted neurons of the olfactory bulb?
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What type of receptors detect chemical changes from outside the body?
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What do taste receptors respond to?
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What type of information is transmitted in the endocrine system?
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What is produced following the graded depolarization in olfactory transduction?
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Which of the following is a common aspect of both neural and endocrine regulation?
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Which hormone is also classified as a neurotransmitter in the central nervous system?
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In hormone interactions, how does a target tissue typically respond?
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What is the primary messenger in the nervous system?
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Which of the following statements regarding the mechanisms for turning off target cell activity is true?
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Which part of the brain is connected to the olfactory system through the piriform cortex?
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What does the term 'permissive effects' refer to in hormone interactions?
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What is the range of half-lives for hormones circulating in the blood?
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How are most hormones removed from the blood?
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What happens to tissues when hormone concentrations are above normal physiological levels?
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Which hormone is mentioned as making the intestines more responsive to calcium absorption?
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What primarily influences tissue response to hormones?
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What may occur due to high pharmacological concentrations of hormones?
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What is the main consequence of a hormone's half-life?
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Study Notes
Auditory Pathway
- The auditory pathway starts with the vestibulocochlear nerve and ends in the auditory cortex of the temporal lobe.
- The signal travels from the vestibulocochlear nerve to the cochlear nuclei in the medulla oblongata and pons.
- Then it continues to the inferior colliculus of the midbrain.
- Next, the signal reaches the medial geniculate body of the thalamus.
- Finally, the signal arrives at the target - the auditory cortex of the temporal lobe.
Hearing Impairment
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Conduction deafness: Sound waves are unable to reach the inner ear.
- This can be caused by earwax buildup, fluid in the middle ear, eardrum damage, or bone overgrowth in the middle ear.
- Affects all sound frequencies.
- Can be improved with hearing aids.
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Sensorineural/perceptive deafness: Nerve impulses are not transmitted from the cochlea to the auditory cortex.
- Can be caused by damaged hair cells (from loud noises).
- May affect only certain sound frequencies.
- Can be improved with cochlear implants.
- Presbycusis: Age-related hearing impairment.
Cutaneous Receptors
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Pain, cold, and heat receptors: Naked dendrites of sensory neurons
- Free nerve endings
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Touch and pressure receptors: Special structures around their dendrites
- Merkel’s disks
- Meissner’s corpuscles
- Pacinian corpuscles
Smell
- Smell: Also known as olfaction.
- Olfactory receptors: Located in the olfactory epithelium of the nasal cavity.
- Basal stem cells: Replace receptors damaged by the environment.
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Odor binding mechanism:
- G-protein coupled
- Odor binding activates adenylate cyclase.
- Adenylate cyclase produces cAMP and PPi (pyrophosphate).
- cAMP opens Na+ and Ca2+ channels.
- Produces a graded depolarization, triggering an action potential.
- Great sensitivity due to amplification with up to 50 G-proteins associated with a single receptor protein.
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Signal path:
- Olfactory receptors → olfactory bulb (glomeruli) → mitral and tufted neurons → primary olfactory cortex (frontal and parietal lobes)
- Interconnections with amygdala, hippocampus, and limbic system via the piriform cortex.
Taste and Smell
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Chemoreceptors: Detect chemical changes in the body.
- Interoceptors: Detect internal changes.
- Exteroceptors: Detect external changes, including taste and smell.
- Taste: Responds to chemicals dissolved in food and drink.
- Smell: Responds to chemical molecules in air.
Taste Pathways
- Facial and glossopharyngeal nerves → Medulla oblongata (NST) → Thalamus → Primary gustatory cortex of insula, somatosensory cortex of parietal lobe, and prefrontal cortex.
Smell
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Olfactory apparatus:
- Smell is also called olfaction.
- Olfactory receptors are located in the olfactory epithelium of the nasal cavity.
- Basal stem cells replace receptors damaged by the environment.
- Olfactory Sensory Neuron (OSN) specialization: A mature OSN expresses only one odorant receptor (OR) gene.
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Smell mechanism:
- G-protein coupled.
- Odor binding activates adenylate cyclase to make cAMP and inorganic pyrophosphate (PPi).
- cAMP opens sodium (Na+) and calcium (Ca2+) channels.
- This creates a graded depolarization that stimulates action potentials.
- Each odorant receptor protein can bind to multiple G-proteins (up to 50), amplifying the signal and allowing for high sensitivity.
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Signal path:
- Olfactory receptors → olfactory bulb (glomeruli) → mitral and tufted neurons → primary olfactory cortex (frontal and parietal lobes).
- Interconnections with amygdala, hippocampus, and limbic system through the piriform cortex.
Nervous System vs. Endocrine System
- Nervous system: Transmits information via electrical impulses. Neurotransmitters are the messengers.
- Endocrine system: Transmits information via hormones released into the bloodstream. Hormones are the messengers.
Common Aspects of Neural and Endocrine Regulation
- Receptor specificity: Hormones and neurotransmitters bind to specific receptors.
- Cellular changes: Receptor binding triggers changes within the target cell.
- Signal termination: Mechanisms exist to inactivate or remove the signal.
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Hormone dual function: Some hormones can act as neurotransmitters in the central nervous system (CNS).
- Noradrenaline (Norepinephrine)
- Adrenaline (Epinephrine)
Hormone Interactions
- Target tissue response: A tissue usually responds to multiple hormones.
-
Hormonal effects:
- Synergistic effect: Combined effect is greater than the sum of individual effects.
- Antagonistic effect: One hormone opposes the action of another.
- Permissive effect: One hormone allows another hormone to exert its full effect.
Permissive Effects
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Increased sensitivity: One hormone increases the target cell's responsiveness to another hormone.
- Estradiol makes the uterus more sensitive to progesterone.
- Parathyroid hormone increases the intestines' sensitivity to vitamin D3 for calcium absorption.
Effects of Hormone Concentrations on Tissue Response
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Hormone half-life: The time it takes for a hormone's plasma concentration to decrease by half.
- Ranges from minutes to hours to days.
- Liver is usually the primary site for hormone removal and inactivation.
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Hormone concentration: Tissues only respond within a specific "normal" or physiological concentration range.
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Pharmacological concentrations: High doses may lead to different effects than normal.
- Binding to receptors for different, but related, hormones.
- Widespread side effects.
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Pharmacological concentrations: High doses may lead to different effects than normal.
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Description
This quiz explores the auditory pathway from the vestibulocochlear nerve to the auditory cortex, detailing the steps involved in sound signal transmission. It also examines different types of hearing impairment, including conduction and sensorineural deafness, along with their causes and potential solutions.
