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Questions and Answers
What is the primary function of the counter current flow between the descending and ascending limbs of the vasa recta?
What is the primary function of the counter current flow between the descending and ascending limbs of the vasa recta?
How does the osmolarity in the inner medulla compare to that in the cortex?
How does the osmolarity in the inner medulla compare to that in the cortex?
What substance is actively transported by the ascending limb of Henle's loop?
What substance is actively transported by the ascending limb of Henle's loop?
How does the descending limb of Henle's loop affect the filtrate?
How does the descending limb of Henle's loop affect the filtrate?
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What is the result of the counter current mechanism established by the Henle's loop and vasa recta?
What is the result of the counter current mechanism established by the Henle's loop and vasa recta?
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Which substance is the most toxic and requires large amounts of water for elimination?
Which substance is the most toxic and requires large amounts of water for elimination?
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What is the primary form of excretion in mammals?
What is the primary form of excretion in mammals?
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What type of excretory structure is primarily responsible for removing nitrogenous wastes in earthworms?
What type of excretory structure is primarily responsible for removing nitrogenous wastes in earthworms?
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Which of the following excretory products is least toxic and excreted in solid form?
Which of the following excretory products is least toxic and excreted in solid form?
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Where are the kidneys located in the human body?
Where are the kidneys located in the human body?
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What is the main function of Malpighian tubules found in insects?
What is the main function of Malpighian tubules found in insects?
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Which excretory product is known to conserve water most effectively?
Which excretory product is known to conserve water most effectively?
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What type of excretion is characteristic of many bony fishes and aquatic amphibians?
What type of excretion is characteristic of many bony fishes and aquatic amphibians?
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What initiates the contraction of smooth muscles in the bladder?
What initiates the contraction of smooth muscles in the bladder?
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What is the primary function of the lungs in the excretion process?
What is the primary function of the lungs in the excretion process?
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Which component is NOT typically found in urine?
Which component is NOT typically found in urine?
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What is the average daily excretion of urine for an adult human?
What is the average daily excretion of urine for an adult human?
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What is the term for the neural mechanism that triggers urine release?
What is the term for the neural mechanism that triggers urine release?
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Which of the following is a secondary function of sweat?
Which of the following is a secondary function of sweat?
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What is the pH level of urine typically considered to be?
What is the pH level of urine typically considered to be?
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Which substance is indicative of diabetes mellitus when found in urine?
Which substance is indicative of diabetes mellitus when found in urine?
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What is one of the primary functions of sebum produced by sebaceous glands?
What is one of the primary functions of sebum produced by sebaceous glands?
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Which treatment is used to manage uremia resulting from kidney failure?
Which treatment is used to manage uremia resulting from kidney failure?
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What does kidney transplantation involve?
What does kidney transplantation involve?
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What condition is characterized by the formation of stones of crystallized salts in the kidneys?
What condition is characterized by the formation of stones of crystallized salts in the kidneys?
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What is a common treatment option for managing renal calculi, depending on their size?
What is a common treatment option for managing renal calculi, depending on their size?
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Which condition involves inflammation of the glomeruli in the kidneys?
Which condition involves inflammation of the glomeruli in the kidneys?
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What type of fluid is used in hemodialysis for clearing waste from the blood?
What type of fluid is used in hemodialysis for clearing waste from the blood?
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What can small amounts of nitrogenous wastes be excreted through?
What can small amounts of nitrogenous wastes be excreted through?
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What structure serves as a broad funnel-shaped space inside the hilum of the kidney?
What structure serves as a broad funnel-shaped space inside the hilum of the kidney?
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Which part of the nephron is responsible for the initial filtration of blood?
Which part of the nephron is responsible for the initial filtration of blood?
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What is the primary function of the proximal convoluted tubule (PCT)?
What is the primary function of the proximal convoluted tubule (PCT)?
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Which type of nephron has a long loop of Henle that extends deep into the medulla?
Which type of nephron has a long loop of Henle that extends deep into the medulla?
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What structure is the initial site for the collection of urine from several nephrons?
What structure is the initial site for the collection of urine from several nephrons?
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What is the function of the peritubular capillaries?
What is the function of the peritubular capillaries?
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What distinguishes cortical nephrons from juxta medullary nephrons?
What distinguishes cortical nephrons from juxta medullary nephrons?
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What anatomical feature surrounds the hilum of the kidney?
What anatomical feature surrounds the hilum of the kidney?
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What role does antidiuretic hormone (ADH) play in kidney function?
What role does antidiuretic hormone (ADH) play in kidney function?
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How does the juxtaglomerular apparatus (JGA) respond to a decrease in glomerular blood flow?
How does the juxtaglomerular apparatus (JGA) respond to a decrease in glomerular blood flow?
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What is the effect of angiotensin II in the kidney?
What is the effect of angiotensin II in the kidney?
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What is the primary effect of atrial natriuretic factor (ANF)?
What is the primary effect of atrial natriuretic factor (ANF)?
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Which physiological change triggers the release of ADH?
Which physiological change triggers the release of ADH?
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What initiates the micturition reflex?
What initiates the micturition reflex?
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What is the result of increased aldosterone secretion?
What is the result of increased aldosterone secretion?
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What characteristic of urine is affected by the gradient in the collecting tubule?
What characteristic of urine is affected by the gradient in the collecting tubule?
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What is one of the main effects of ADH on blood vessels?
What is one of the main effects of ADH on blood vessels?
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How does atrial natriuretic factor (ANF) influence kidney filtration?
How does atrial natriuretic factor (ANF) influence kidney filtration?
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Study Notes
Introduction to Excretion
- Animals accumulate substances like ammonia, urea, uric acid, carbon dioxide, water, and various ions through metabolic activities.
- These substances need to be removed.
Types of Excretory Products
- Ammonia: Highly toxic, requires a large amount of water for elimination.
- Urea: Less toxic than ammonia, conserves water.
- Uric Acid: Least toxic, minimal water loss, excreted as a solid.
Mechanisms of Excretion
- Ammonotelism: Excretion of ammonia, common in bony fish, aquatic amphibians, and aquatic insects. Ammonia diffuses across body surfaces or gills.
- Ureotelism: Excretion of urea, common in mammals and many amphibians, and marine fish. Ammonia is converted into urea in the liver and excreted by the kidneys.
- Uricotelism: Excretion of uric acid, common in reptiles, birds, land snails, and insects. Uric acid is excreted in a pellet or paste form, conserving water.
Excretory Structures in Animals
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Invertebrates:
- Protonephridia (flame cells): Found in Platyhelminthes (e.g., planaria), rotifers, some annelids, and cephalochordates. Regulate ionic and fluid volume.
- Nephridia: Found in earthworms and other annelids. Remove nitrogenous wastes and regulate fluid and ionic balance.
- Malpighian tubules: Found in insects, including cockroaches, responsible for nitrogenous waste removal and osmoregulation.
- Antennal glands (green glands): Found in crustaceans; involved in excretion.
Human Excretory System
- Components: Kidneys, ureters, urinary bladder, and urethra.
- Kidney Shape & Color: Reddish-brown, bean-shaped.
- Kidney Location: Between the last thoracic and third lumbar vertebrae, close to the dorsal inner wall of the abdominal cavity.
- Kidney Dimensions: 10-12 cm long, 5-7 cm wide, 2-3 cm thick, weighing 120-170g.
- Hilum: Notch on the inner concave surface where ureter, blood vessels, and nerves enter.
- Renal Pelvis: Funnel-shaped space inside the hilum with projections called calyces.
- Outer Layer: Tough capsule covering the kidney.
Kidney Zones and Nephrons
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Medullary Pyramids: Conical masses in the medulla, projecting into the calyces.
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Renal Columns: Cortex extending between the medullary pyramids.
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Nephrons: Nearly one million complex tubular structures, functional units of kidneys.
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Nephron Parts: glomerulus, Bowman's capsule, PCT, loop of Henle, DCT, collecting duct.
- Glomerulus: A tuft of capillaries formed by the afferent arteriole, filtering blood.
- Bowman's Capsule: A double-walled cup-like structure surrounding the glomerulus.
- Malpighian Body: Combined structure of the glomerulus and Bowman's capsule.
- Proximal Convoluted Tubule (PCT): Coiled network following Bowman's capsule.
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Henle's Loop: Hairpin-shaped structure with descending and ascending limbs.
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Distal Convoluted Tubule (DCT): Coiled region following the ascending limb of the loop of Henle.
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Collecting Duct: The DCTs of many nephrons converge, opening into the renal pelvis through medullary pyramids.
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Types of Nephrons: Cortical and juxtamedullary, distinguished by loop of Henle length.
Urine Formation
- Glomerular Filtration: Filtration of blood through three layers (endothelium, basement membrane, epithelium of Bowman's capsule) creating filtrate.
- Reabsorption: Selective reabsorption of essential nutrients and electrolytes from the filtrate back into the blood.
- Tubular Secretion: Secretion of substances into the filtrate from the blood.
Regulation of Kidney Function
- Hypothalamus & ADH (Vasopressin): Osmoreceptors regulate ADH release, controlling water reabsorption and urine concentration.
- Juxtaglomerular Apparatus (JGA): Monitors blood flow, pressure, and GFR, regulating renin release.
- Renin-Angiotensin Mechanism: Regulates blood pressure and GFR.
- Atrial Natriuretic Factor (ANF): Released in response to increased blood flow, working against renin-angiotensin.
Micturition
- Micturition reflex initiates actions that lead to urine release from the body.
Role of Other Organs in Excretion
- Lungs: Main role is CO2 removal, also excrete water.
- Liver: Processes and excretes substances like bilirubin, bile, cholesterol.
- Skin: Sweat glands remove water, salts, and some waste products.
Diseases
- Uremia: Accumulation of urea in the blood due to kidney failure.
- Kidney Transplantation: Replacing a failed kidney with a healthy donated kidney.
- Renal Calculi (Kidney Stones): Formation of stones in the kidney.
- Glomerulonephritis: Inflammation of the glomeruli.
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Description
Explore the processes and types of excretion in animals, including ammonia, urea, and uric acid. Understand the mechanisms like ammonotelism, ureotelism, and uricotelism, along with the structures involved in excretion. This quiz will test your knowledge on how different organisms manage waste removal.
