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Questions and Answers
What components compose the blood-brain barrier?
What components compose the blood-brain barrier?
Which substances can easily cross the blood-brain barrier?
Which substances can easily cross the blood-brain barrier?
What is a unique feature of circumventricular organs?
What is a unique feature of circumventricular organs?
Why is the median eminence important in the context of the blood-brain barrier?
Why is the median eminence important in the context of the blood-brain barrier?
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What distinguishes spatially focused synaptic connectivity from widely divergent patterns?
What distinguishes spatially focused synaptic connectivity from widely divergent patterns?
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What characterizes cell necrosis?
What characterizes cell necrosis?
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Which factor is NOT a trigger for apoptosis?
Which factor is NOT a trigger for apoptosis?
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Which condition is associated with both cell necrosis and apoptosis?
Which condition is associated with both cell necrosis and apoptosis?
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What is the primary acid-base disturbance in the case presented?
What is the primary acid-base disturbance in the case presented?
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In a situation involving cell apoptosis, which of the following is a common appearance feature?
In a situation involving cell apoptosis, which of the following is a common appearance feature?
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Which laboratory result can indicate metabolic acidosis?
Which laboratory result can indicate metabolic acidosis?
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What is the typical consequence of uncontrolled cell necrosis?
What is the typical consequence of uncontrolled cell necrosis?
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What role does the immune system play in apoptosis?
What role does the immune system play in apoptosis?
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What is the primary function of calcitonin released by parafollicular cells?
What is the primary function of calcitonin released by parafollicular cells?
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What is the role of iodine in the synthesis of thyroid hormones?
What is the role of iodine in the synthesis of thyroid hormones?
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Which of the following best describes the metabolic function of thyroid hormones?
Which of the following best describes the metabolic function of thyroid hormones?
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How is T3 and T4 released from the thyroid follicles?
How is T3 and T4 released from the thyroid follicles?
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What structure in the thyroid serves as the storage center for hormones?
What structure in the thyroid serves as the storage center for hormones?
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Why is the storage of T3 and T4 in colloid important?
Why is the storage of T3 and T4 in colloid important?
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What are the major physiological effects of thyroid hormones?
What are the major physiological effects of thyroid hormones?
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What is the function of the Na-K pump formed by thyroid hormones?
What is the function of the Na-K pump formed by thyroid hormones?
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What is the primary role of afferent neurons?
What is the primary role of afferent neurons?
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Which ion has an equilibrium potential of -90 mV?
Which ion has an equilibrium potential of -90 mV?
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What factors primarily influence the resting membrane potential?
What factors primarily influence the resting membrane potential?
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In which part of the nervous system are interneurons exclusively found?
In which part of the nervous system are interneurons exclusively found?
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What does the equilibrium potential indicate about ion movement?
What does the equilibrium potential indicate about ion movement?
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During an action potential, which ion primarily flows out of the cell during the repolarization phase?
During an action potential, which ion primarily flows out of the cell during the repolarization phase?
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How does the presence of leak channels affect resting membrane potential?
How does the presence of leak channels affect resting membrane potential?
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What is the equilibrium potential for sodium ions (Na+)?
What is the equilibrium potential for sodium ions (Na+)?
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What condition is characterized by an elevated osmolarity of the ECF due to increased solute concentration?
What condition is characterized by an elevated osmolarity of the ECF due to increased solute concentration?
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Which of the following is a cause of hypotonic alterations in the ECF?
Which of the following is a cause of hypotonic alterations in the ECF?
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What effect does acidosis have on potassium levels in the ECF?
What effect does acidosis have on potassium levels in the ECF?
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How does insulin affect the movement of potassium between ICF and ECF?
How does insulin affect the movement of potassium between ICF and ECF?
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Which of the following conditions can lead to hyperchloremia?
Which of the following conditions can lead to hyperchloremia?
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What can result from inadequate water intake leading to hypernatremia?
What can result from inadequate water intake leading to hypernatremia?
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What effect do catecholamines have on potassium movement in the context of ECF?
What effect do catecholamines have on potassium movement in the context of ECF?
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Which factor is primarily responsible for potassium moving into the cells during acute hyperkalemia treatment?
Which factor is primarily responsible for potassium moving into the cells during acute hyperkalemia treatment?
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Study Notes
Conditions Affecting ECF
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Isotonic Alterations: ECF fluid concentration changes without altering osmolarity between ICF and ECF.
- Causes include isotonic volume depletion (e.g., hemorrhage, wound drainage) and isotonic volume excess (e.g., excess IV fluids, hyperaldosteronism).
-
Hypertonic Alterations: ECF osmolarity increases due to higher solute concentration.
- Causes include hypernatremia (inadequate water intake, hypertonic saline), water deficit, and hyperchloremia (often due to excess sodium or ammonium chloride diuretics).
-
Hypotonic Alterations: ECF osmolarity decreases because of a drop in solute concentration.
- Causes include hyponatremia (diuretics, vomiting, diarrhea), water excess (renal failure, SIADH), and hypochloremia (loss of HCl, excessive bicarbonate).
Potassium Balance and Shifts
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Changes in ECF/ICF pH affect potassium levels:
- Acidosis causes H+ to enter cells, leading to increased potassium levels (hyperkalemia).
- Alkalosis causes K+ to enter cells, resulting in decreased potassium levels (hypokalemia).
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Insulin influences potassium:
- Increased insulin promotes K+ entry into cells, aiding glycogen formation, while decreased insulin keeps K+ outside.
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Catecholamines affect potassium movement:
- B2 adrenergic stimulation (e.g., epinephrine) increases intracellular K+.
- Alpha 2 adrenergic stimulation causes K+ to exit cells.
Types of Cell Death
- Necrosis: Unintentional cell death characterized by swelling and cell lysis.
- Apoptosis: Controlled cell death marked by cell shrinkage; triggered by viral infection, DNA damage, or cell stress.
Homeostatic Feedback Systems
- Negative feedback loops maintain vital biological parameters.
- Control systems of the body include efferent and afferent neurons, which communicate through interneurons.
Equilibrium Potential
- Represents the membrane potential at which there is no net ion movement.
- Chemical driving forces are determined by concentration differences, while electrical driving forces are influenced by membrane potential.
- K+ has an equilibrium potential of -90 mV, while Na+ has +60 mV.
Resting Membrane Potential
- The resting membrane potential is typically -86 mV.
- Factors influencing it include ion presence (K+, Na+, Cl-, Ca2+), their equilibrium potentials, and permeability, especially for K+.
Action Potential Changes
- Resting potential maintained by K+ leak channels.
- Membrane potential changes during action potential involve depolarization, repolarization, and hyperpolarization.
Circumventricular Organs
- Specialized areas of the BBB with increased permeability.
- Facilitate direct interactions between circulating hormones and the brain, allowing immune signals (e.g., cytokines) to influence hypothalamic function.
Synaptic Connectivity Patterns
- Spatially focused connectivity features direct communication to specific neurons, while widely divergent patterns allow for broader dissemination of signals across many neurons.
Thyroid Hormones
- Comprised of follicles lined with follicular cells, storing T3 and T4 due to iodine uptake.
- Iodine is critical for hormone synthesis and must be acquired through diet.
Physiological Effects of Thyroid Hormone
- Regulate metabolic activity and energy consumption by increasing BMR.
- Stimulates formation of Na-K pumps, gluconeogenic enzymes, respiratory enzymes, and adrenergic receptors enhancing the SNS response.
Adrenal Gland Zones
- The adrenal glands have two major zones: the cortex and the medulla, differing in hormone production and physiological roles.
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