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What role does the external sphincter play in urination?
Which nerve is important for the control of the external sphincter during urination?
What happens when the inhibition from the brain becomes more potent than voluntary contraction signals?
What is the role of the micturition reflex in urination control?
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How does potty training affect the control over urination?
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What is primarily affected when a child's bladder becomes too full?
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Which part of the brain contains areas that can inhibit the micturition reflex?
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What does the contraction of the external sphincter during potty training signify?
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What does voluntary urination primarily involve?
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Urination typically results in emptying the bladder with over 20 milliliters still remaining.
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What kind of reflex is stimulated by stretching the walls of the bladder?
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The process of filtering liquid through the nephron is referred to as __________.
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How much urine does an average person urinate daily?
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Match the following terms with their definitions:
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The external sphincter facilitates urination by relaxing.
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The nephron is responsible for the __________ of urine.
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What is primarily reabsorbed in the nephron?
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Secretion of substances in the renal tubules is primarily done through passive transport.
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What happens to dangerous substances in the kidneys?
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The process of moving substances from the blood into the renal tubules is called __________.
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Match the following terms with their descriptions:
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Which of the following substances is known to be actively secreted in excess to eliminate toxicity?
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Reabsorption occurs at a higher rate than excretion for most electrolytes in the nephron.
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What is the main reason for increased permeability of the glomeruli to plasma proteins?
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The __________ tubule is primarily responsible for reabsorption of many substances.
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The presence of albumin in the urine is normal and indicates healthy kidney function.
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What type of microscopy shows flattened podocytes in cases of increased permeability?
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The podocytes are normally ______ charged, which provides a barrier to protein filtration.
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What is the most common demographic affected by glomerular permeability issues?
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Match the following forces with their correct descriptions:
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In pathological conditions, there can be a Bowman's capsule osmotic pressure due to protein filtration.
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What specific protein is primarily filtered in the case of increased albumin in urine?
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What effect does an increase in Bowman's capsule pressure have on glomerular filtration?
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The normal colloid osmotic pressure of plasma entering the glomerular capillaries is 36.
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What happens to the plasma protein concentration when water is filtered out?
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In postrenal disease, such as a kidney stone, Bowman's capsule pressure can increase from ___ to ___.
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Match the following terms with their definitions:
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What is the average colloid osmotic pressure as blood exits the glomerular capillaries?
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Plasma proteins are found in Bowman's capsule.
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What is a potential cause of increased Bowman's capsule pressure?
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What effect does an increase in arterial resistance have on renal blood flow?
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Increasing efferent arterial resistance affects renal blood flow similar to increasing afferent arterial resistance.
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How does low dose dopamine affect renal perfusion?
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When glomerular filtration decreases due to increased arterial resistance, this also leads to increased concentration of __________ in the plasma.
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Match the following mechanisms with their effects:
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What is the primary reason for the decrease in glomerular filtration when efferent arterial resistance is increased?
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High doses of dopamine are beneficial for renal function throughout the entire dosing range.
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What happens when too much resistance is applied on the arterial side of the kidneys?
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Study Notes
Micturition Reflex and External Sphincter Control
- The micturition reflex triggers urination when the bladder stretches due to filling.
- Pedendal nerves control the external sphincter, which contracts to inhibit urination.
- Strong inhibition from the brain can lead to urination despite voluntary contractions of the external sphincter.
- Potty training involves teaching toddlers to control their external sphincters to avoid accidental urination.
Brain Centers and Urination
- Specific brain regions can inhibit or facilitate the micturition reflex.
- The pons in the brainstem and cerebral cortex play key roles in controlling urination.
- Potty-trained individuals rely on higher brain control over spinal reflexes for urination.
Glomerular Filtration and Proteinuria
- Glomeruli are typically impermeable to plasma proteins; damage can lead to increased protein excretion (proteinuria).
- Podocytes, negatively charged cells in the glomerulus, are crucial for filtering proteins, and their damage increases albumin filtration.
- Cytokine secretion from T-cells may cause injury to podocytes, leading to heightened glomerular permeability.
Filtration Dynamics
- Renal filtration is driven by the balance of hydrostatic and colloid osmotic pressures in glomeruli.
- Increased Bowman's capsule pressure (due to obstructions like kidney stones) can reduce glomerular filtration rates.
- Colloid osmotic pressure increases as plasma proteins concentrate, opposing filtration flow.
Mediation of Urination and Muscle Contraction
- Voluntary urination involves abdominal muscle contraction, increasing bladder pressure and extending walls to stimulate micturition reflex.
- Stretch receptors in the bladder trigger further micturition reflexes and inhibit the external sphincter relaxation.
Tubular Handling of Substances
- The kidneys filter significant amounts of substances daily, reabsorbing most of what is filtered.
- Some substances are neither reabsorbed nor secreted, while harmful compounds may be filtered and additionally secreted into the renal tubules.
Importance of Secretion and Reabsorption
- Active transport mainly mediates secretion, impacting elements like potassium and hydrogen ions.
- Certain drugs and toxins are poorly reabsorbed, necessitating renal secretion to maintain homeostasis.
Influence of Arteriolar Resistance
- Increased resistance in afferent arterioles decreases renal blood flow and glomerular filtration rates.
- Locally squeezing efferent arterioles can enhance filtration pressures initially but may lower rates due to higher colloid osmotic pressures.
Dopaminergic Effects on Urine Output
- Low-dose dopamine can enhance renal blood flow and filtration, while high doses may cause vasoconstriction and decrease urine output due to differing receptor effects.
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Description
This quiz explores the anatomy and physiology of the external sphincter, focusing on its control mechanisms and the role of the pedendal nerves. Understanding how the inhibition of vitreousion reflux impacts bladder function is crucial for grasping the overall functionality of these systems.