Chapter 10: Renal/Excretory System Flashcards
(140 cards)
1
Q
What structures make up the renal/excretory system?
A
- Pair of kidneys
-pair of ureters
-urinary bladder
-urethra.
2
Q
What is the function of the ureters?
A
Convey urine from kidneys to urinary bladder.
3
Q
What is the function of the urinary bladder?
A
Stores urine until voided, made of smooth muscles.
4
Q
What is the function of the urethra?
A
Conveys urine from bladder to outside (shorter in men).
5
Q
What is the anatomical location of the kidneys?
A
-Bean-shaped
-bilateral
-located in the lumbar region (12th thoracic to 3rd lumbar vertebrae).
6
Q
Why is the right kidney lower than the left kidney? n size
A
-right kidney is 2 cm lower than the left due to the position of the liver
-4.5 inches long, 2.5 inches wide, and 1 inch thick.
7
Q
What are the layers surrounding the kidneys?
A
Fibrous capsule
Perirenal fat
Renal fascia
Pararenal fat
8
Q
What is the renal papilla’s role in the kidney?
A
Collecting ducts open into minor calyces, which drain into major calyces.
9
Q
What is the structure of the kidney?
A
Major calyx: Minor calyces combine to form the major calyx.
Renal pelvis: Collects urine from the major calyx.
Renal column: Space between renal pyramids, containing blood vessels and nerves.
Cortex: Outer part, contains proximal convoluted tubule (PCT), glomerulus, distal convoluted tubule (DCT).
Medulla: Inner part, contains Loop of Henle, collecting duct, and collecting tubules.
10
Q
What is the orientation of the nephron within the kidney?
A
Cortex: Bowman’s capsule, PCT, DCT.
Medulla: Loop of Henle, collecting ducts, collecting tubules.
11
Q
What is the function of the nephron in the kidney?
A
The nephron is the functional unit of the kidney, involved in filtration, reabsorption, and secretion to form urine.
12
Q
What is the blood supply to the kidneys?
A
The kidneys receive 20-25% of cardiac output (~1200-1250 mL/min).
13
Q
Describe the blood flow pathway to the kidneys.
A
Left ventricle → Aorta → Renal artery → Segmental artery → Interlobar artery → Arcuate artery → Cortical radiate artery → Afferent arteriole → Glomerulus -> efferent arteriole → Cortical radiate vein → Arcuate vein → Interlobar vein → Renal vein → Inferior vena cava → Right atrium.
14
Q
What happens at the glomerulus?
A
Filtration occurs, blood is filtered into glomerular filtrate.
15
Q
Describe the return flow of blood from the kidneys
A
Efferent arteriole → Cortical radiate vein → Arcuate vein → Interlobar vein → Renal vein → Inferior vena cava → Right atrium.
16
Q
What is the structure and function of Bowman’s capsule?
A
- cup-shaped
-contains the glomerulus
-It is part of the renal corpuscle where blood filtration takes place.
17
Q
What is the difference between the parietal and visceral layers of Bowman’s capsule?
A
Parietal layer: Flat, squamous cells.
Visceral layer: podocytes (Specialized cells) that wrap around the capillaries with foot processes.
18
Q
How does filtration occur in Bowman’s capsule?
A
Blood passes through fenestrated capillaries → Podocyte foot processes → Filtrate goes through filtration slits into Bowman’s space.
19
Q
What is the purpose of the podocytes in Bowman’s capsule?
A
Podocytes have foot processes that wrap around the capillaries, aiding in filtration by creating filtration slits.
20
Q
How many nephrons are in each kidney?
A
Each kidney has approximately 1 million nephrons.
21
Q
What are the main components of the renal corpuscle?
A
Glomerulus + Bowman’s capsule.
22
Q
What are the components of the Loop of Henle and their functions?
A
Descending limb: Permeable to water and sodium, thin segment with flat cells.
Ascending limb: Permeable only to sodium (not water), thick segment with cuboidal cells.
23
Q
What happens in the distal convoluted tubule (DCT) and collecting tubule?
A
They combine to form the collecting duct, which opens at the minor calyx and carries urine out.
24
Q
How much reabsorption occurs in the PCT, and what is reabsorbed?
A
80% of reabsorption occurs in the PCT, including sodium and water.
25
What is the role of the efferent arteriole in blood supply to the nephron?
It forms a capillary bed around the nephron to provide blood supply.
26
What are the two types of capillary beds around the nephron?
Vasa recta: Capillary bed around the Loop of Henle.
Peritubular plexus: Capillary bed around the PCT and DCT, responsible for returning substances to the body.
27
What are the characteristics of PCT and DCT cells?
PCT cells: Cuboidal, with microvilli (brush border for 80% reabsorption).
DCT cells: Cuboidal, without microvilli (secretory, not absorptive).
28
IWhat is the function of intercalated cells in the kidney?
Type A cells: Excrete H+ ions to urine in acidosis (too MUCH ACID
.
Type B cells: Excrete HCO3- to urine in alkalosis (too little acid).
29
What do principal cells do in the nephron?
Principal cells reabsorb sodium under aldosterone control through ENa channels for sodium entry into the cells (on the apical side).
30
What is the structure of the nephron?
Includes the afferent arteriole, efferent arteriole, proximal tubule (PCT), ascending and descending limbs of the Loop of Henle, DCT, collecting tubule, collecting duct, peritubular plexus, and vasa recta.
31
What is the difference between the afferent and efferent arterioles?
Afferent arteriole: Wider, brings blood into the glomerulus.
Efferent arteriole: Narrower, carries blood out of the glomerulus.
32
What are the two types of nephrons, and how do they differ?
Cortical nephrons (85%): Shorter Loop of Henle, make urine 4x more concentrated than plasma.
Juxtamedullary nephrons (15%): Longer Loop of Henle, highly concentrated urine, up to 16x more concentrated (seen in desert rodents like Jerboa).
33
What is the juxtaglomerular apparatus (JGA)?
The JGA regulates Glomerular Filtration Rate (GFR) through macula densa cells and juxtaglomerular cells.
34
How do macula densa cells influence GFR?
If the filtrate is highly concentrated, macula densa cells secrete adenosine, which causes vasoconstriction of the afferent arteriole, reducing GFR.
If the filtrate is dilute, they secrete prostaglandin E2 (PGE2), causing vasodilation and increasing GFR.
35
What is the role of juxtaglomerular (JG) cells in regulating blood pressure?
JG cells in the afferent arteriole release renin (released when bp is too low)
which converts angiotensinogen to angiotensin I. ACE converts angiotensin I to angiotensin II, causing vasoconstriction of the efferent arteriole, restoring GFR.
36
What is the Glomerular Filtration Rate (GFR)?
GFR is 125 mL/min or 180 liters of filtrate/day, with 99% of filtrate being reabsorbed, leaving 2.4 liters excreted as urine/day.
37
What are the functions of the kidneys?
The kidneys remove nitrogenous wastes (non-protein nitrogen), regulate water balance, and maintain electrolyte levels.
38
How is ammonia produced in the body, and why must it be eliminated?
Ammonia is produced by oxidative deamination of amino acids. It is toxic, highly soluble in water, and must be eliminated to avoid harmful effects.
39
What are ammonotelic animals, and give an example.
Ammonotelic animals excrete nitrogen as ammonia. Example: Fish, because they can wash out ammonia easily in water.
40
What are ureotelic animals, and give an example.
Ureotelic animals convert ammonia into urea for excretion. Example: Humans, who excrete urea in urine via the urea cycle in the liver.
41
Describe the urea cycle (ornithine cycle).
In the liver:
CO2 + NH3 forms Carbamoyl Phosphate (1 Nitrogen).
Carbamoyl Phosphate combines with Ornithine (2 Nitrogens) to form Citrulline.
Citrulline combines with Aspartic acid (1 Nitrogen) to form Arginino-Succinic Acid.
Arginino-Succinic Acid is converted to Arginine and Fumaric Acid.
Arginine is split to form Ornithine and Urea (2 Nitrogens).
42
What is uremia?
Uremia is high blood urea, which can be toxic and lead to symptoms like vomiting.
43
How can renal failure be diagnosed?
Intravenous Pyelography (IVP) is a test where iodine-based contrast is injected into the vein. It shows areas of filtration in the kidney (light areas) and blockage (dark areas) using improved X-ray imaging.
44
What is nephroptosis, and what problem does it cause?
Nephroptosis is when the kidney drops from its normal position into the pelvic cavity, causing a blockage of the ureter.
45
What is hydronephrosis?
Hydronephrosis is the swelling of the kidney due to urine buildup from a blockage or nephroptosis.
46
What are renal calculi, and how are they treated?
Renal calculi are kidney stones, often formed from calcium phosphate. Treatment includes lithotripsy (pulverizing stones with a laser) and ureteral stents to relieve blockage.
47
What is crystalluria, and what causes the pain?
Crystalluria is the formation of oxalate crystals due to high acidity. The sharpness of the crystals causes acute, radiating pain when they move, often from the back to the front.
48
How can crystalluria be treated?
Crystalluria can be treated by drinking water to induce diuresis or using an alkalizer to reduce acidity.
49
What is renal aplasia?
Renal aplasia is a condition where one or both kidneys fail to develop.
50
What is renal dysplasia?
Renal dysplasia is a malformation of the kidneys during development.
51
What is renal hypoplasia?
underdeveloped, small kidneys.
52
What is chronic renal failure?
Chronic renal failure occurs when the kidneys no longer function and cannot regenerate, requiring dialysis or a kidney transplant for survival.
53
How does the positioning of the kidneys differ?
The right kidney is 2 cm lower than the left and located in the lumbar region
54
What are uricotelic animals, and how do they handle nitrogenous waste?
Uricotelic animals convert nitrogen to uric acid, which is non-toxic, insoluble, and crystalline. Uric acid is kept in the body longer and does not require water for excretion.
It can cause gout in humans due to crystal deposition in bone joints. Examples: Reptiles, birds.
55
Why is uric acid synthesis energetically expensive?
Uric acid synthesis requires 6 ATP molecules for its formation from purines (Adenine and Guanine), making it more "expensive" in terms of energy.
56
What is creatine, and how is it used in muscle energy metabolism?
Creatine is a straight-chain compound (NH2-NH-CH2-CO2-H). In muscles, it can be phosphorylated to creatine phosphate using creatine kinase, which provides energy during muscle contraction by donating its phosphate group to ADP, forming ATP.
57
What is the role of creatinine, and how is it used to measure kidney function?
Creatinine is a cyclic compound that is freely filtered in the kidneys, not reabsorbed, and may be secreted. It is used to estimate Glomerular Filtration Rate (eGFR). High creatinine levels indicate poor kidney function and a low GFR.
58
What is the normal range for creatinine levels in blood?
Normal creatinine levels range from 0.7 to 1.3 mg/100 ml of blood.
59
What are the ideal characteristics of substances used to measure GFR?
Substances used to measure GFR should be:
Freely filtered by the kidneys
Not reabsorbed
Not secreted
60
What role do kidneys play in electrolyte balance?
Kidneys regulate electrolyte balance by reabsorbing sodium, bicarbonate, and calcium, while secreting potassium and acidic ions into the filtrate. They also excrete phosphate, sulfate, toxins, antibiotics, poisons, and conjugated hormones in urine.
61
How do kidneys regulate the volume of water in the body?
62
How do kidneys maintain blood pH, and what role do Intercalated Cells play?
Kidneys help maintain blood pH (7.3 - 7.4) by regulating H⁺ and HCO₃⁻ levels. Intercalated cells in the nephrons perform this function:
Type A: Active during acidosis (excrete H⁺, retain HCO₃⁻)
Type B: Active during alkalosis (excrete HCO₃⁻, retain H⁺)
63
What happens in acidosis and alkalosis, and how do kidneys respond?
Acidosis: Too many H⁺ ions, kidneys excrete H⁺ and retain HCO₃⁻.
Alkalosis: Not enough H⁺ ions, kidneys excrete HCO₃⁻ and retain H⁺.
64
How do kidneys regulate blood pressure?
Kidneys regulate blood pressure via hormones:
Aldosterone: Promotes sodium and water retention.
ADH (Anti-Diuretic Hormone): Promotes water retention; absence leads to diuresis (increased water excretion).
Angiotensin II: Increases blood pressure by constricting blood vessels.
65
What is diabetes insipidus and how is it related to ADH?
Diabetes insipidus is a condition where there is a lack of ADH, causing excessive urinary water loss (diuresis) without affecting blood sugar levels.
66
What triggers the secretion of erythropoietin and what is its function?
Hypoxemia (low oxygen levels in the blood) triggers the kidneys to secrete erythropoietin, which stimulates red blood cell production in the bone marrow to improve oxygen transport.
67
How do kidneys help in the elimination of drugs, antibiotics, and degraded hormones?
Through tubular secretion, kidneys excrete substances that are not reabsorbed back into the bloodstream, including drugs, antibiotics, and degraded hormones.
68
How is Vitamin D3 activated in the kidneys, and what is its function?
Vitamin D3 is activated in the kidneys by the enzyme 1α-hydroxylase, converting 25-OH-cholecalciferol to 1,25-di-OH-cholecalciferol (active Vitamin D3). This active form is necessary for calcium absorption in the intestines.
69
What is gluconeogenesis, and where does it occur?
Gluconeogenesis is the process of making glucose from non-carbohydrates like proteins. It occurs in the liver and kidneys, especially during stress or starvation to provide glucose for neurons.
70
What is the renal cortex and what does it contain?
The cortex is the outer part of the kidney; it contains the glomerulus, proximal convoluted tubule (PCT), and distal convoluted tubule (DCT).
71
What structures are found in the renal medulla?
The medulla contains the Loop of Henle, collecting tubules, and collecting ducts.
72
What are renal columns and what do they contain?
Renal columns are spaces between renal pyramids that contain blood vessels and nerves.
73
What are renal pyramids?
Cone-shaped structures in the medulla that contain parts of the nephron and collecting ducts.
74
What forms a major calyx?
Multiple minor calyces combine to form a major calyx.
75
What is the function of the major calyx?
It collects urine from minor calyces and funnels it into the renal pelvis.
76
What is the renal pelvis?
A funnel-like structure that collects urine from major calyces and sends it to the ureter.
77
How much of the cardiac output do the kidneys receive?
20–25% (~1200–1250 mL/min)
78
How often is the entire blood volume filtered by the kidneys?
Every ~4 minutes
79
What is the blood flow pathway into the kidney (arterial)?
Left ventricle → Aorta → Renal artery → Segmental → Interlobar → Arcuate → Cortical radiate → Afferent arteriole → Glomerulus → Efferent arteriole
80
Why is the afferent arteriole wider than the efferent arteriole?
To allow more blood into the glomerulus and increase filtration pressure
81
Where does filtration occur in the nephron?
The glomerulus
82
What is the venous return pathway from the kidney?
Efferent arteriole → Cortical radiate v. → Arcuate v. → Interlobar v. → Renal v. → Inferior vena cava
83
How many nephrons per kidney, and how long are they?
~1 million; ~3.5 cm long
84
What makes up the renal corpuscle?
Glomerulus + Bowman’s capsule
85
What cells make up the visceral layer of Bowman’s capsule?
Podocytes (with foot processes that form filtration slits)
86
Through what structures does blood pass during filtration in the corpuscle?
Fenestrated capillaries → Podocyte slits → Bowman’s space
87
Which nephron tubule has microvilli and handles most reabsorption?
Proximal convoluted tubule (PCT) – cuboidal cells, brush border
88
What are the characteristics of the DCT?
Cuboidal cells, no microvilli, mainly secretory
89
Permeability of Loop of Henle Limbs
Descending limb: permeable to water & Na⁺
Ascending limb: permeable to Na⁺ only
90
Where does urine flow after the collecting ducts?
Minor calyx → out as urine
91
PWhat % of reabsorption occurs in the PCT?
About 80% (sodium and water)
92
What are intercalated cells and their types?
Type A: excrete H⁺ (acidosis)
Type B: excrete HCO₃⁻ (alkalosis)
93
What do principal cells do, and what hormone regulates them?
Reabsorb sodium via ENaC channels, regulated by aldosterone
94
What is the vasa recta?
Capillary bed around the Loop of Henle
95
What is the peritubular plexus?
Capillary bed around the PCT and DCT, returns reabsorbed substances to blood
96
What happens after the DCT?
DCTs join to form collecting tubules, which merge into the collecting duct → opens at the minor calyx to release urine
97
Why is the afferent arteriole wider than the efferent arteriole?
To allow more blood into the glomerulus and create filtration pressure
98
What is the glomerular filtration rate (GFR)?
A: 125 mL/min or 180 L/day
Urine excreted: ~2.4 L/day
Filtrate reabsorbed: ~99%
99
What is the order of renal blood flow (arterial)?
Aorta → Renal a. → Segmental a. → Interlobar a. → Arcuate a. → Cortical radiate a. → Afferent arteriole → Glomerulus → Efferent arteriole
100
What are the two types of nephrons and their percentages?
Cortical nephrons: 85%
Juxtamedullary nephrons: 15%
101
What are the features of cortical nephrons?
Short Loop of Henle
Used under normal conditions
Make urine 4× as concentrated as plasma (1200 mOsm vs 300 mOsm)
102
What are the features of juxtamedullary nephrons?
Long Loop of Henle
Used in stress & dehydration
Make highly concentrated urine
Can reach 16× concentration (in Jerboa, not humans)
103
What are the parts of a nephron?
Renal corpuscle → PCT → Loop of Henle (descending + ascending) → DCT → Collecting tubule → Collecting duct → Minor calyx
104
What makes up the renal corpuscle?
Glomerulus + Bowman’s capsule
105
What do podocytes do?
Form filtration slits in the visceral layer of Bowman’s capsule
106
Describe the Proximal Convoluted Tubule (PCT)
Cuboidal cells with microvilli; ~80% of reabsorption occurs here
107
Describe the Distal Convoluted Tubule (DCT)
Cuboidal cells without microvilli; functions mostly in secretion
108
What are the characteristics of the Loop of Henle?
Descending limb: thin due to passive transport, flat cells; permeable to water
Ascending limb: thick, cuboidal due to active; permeable to Na⁺ only
109
What is the function of the JUXTAGLOMERULAR APPARATUS?
Regulates glomerulus filtration rate by mascula densa (sense sodium levels-> low sodium=low BP/GFR) and JG cells (renin released when BP low)
110
What do macula densa cells do?
Detect filtrate concentration in DCT
111
What happens if filtrate is too concentrated?
Macula densa → Adenosine → Afferent arteriole vasoconstricts → ↓ GFR
112
What happens if filtrate is too dilute?
Macula densa → PGE₂ → Afferent arteriole vasodilates → ↑ GFR
113
What are Juxtaglomerular (JG) cells?
Smooth muscle cells in afferent arteriole; secrete renin
114
What is the Renin-Angiotensin Pathway?
Renin → Angiotensinogen → Ang I → ACE → Ang II → vasoconstricts efferent arteriole → restores GFR
115
What are Ammonotelic animals?
Excrete ammonia directly (e.g., fish); require lots of water
116
What are Ureotelic animals ?
Convert ammonia → urea in liver; less toxic, water-soluble, humans
117
What are Uricotelic animals?
Convert nitrogen → uric acid (crystalline, non-toxic, no water needed); e.g., birds, reptiles
118
Why is uric acid problematic in humans?
It forms crystals in joints → Gout
119
What are the steps of the Urea Cycle?
Carbamoyl phosphate + Ornithine → Citrulline
Citrulline + Aspartate → Arginino-succinate
Arginino-succinate → Arginine + Fumarate
Arginine → Urea + Ornithine (via Arginase)
Urea = NH₂–CO–NH₂
120
What is uremia?
High blood urea levels; leads to vomiting, toxicity
121
What is Intravenous Pyelography used for?
Detects filtration & kidney function using contrast dye in X-ray
Light areas = filtration
Dark areas = no filtration
122
What is Nephroptosis?
Kidney drops into pelvic cavity → blocks ureter
123
What is Hydronephrosis?
Swelling of kidney due to urine buildup
124
How are kidney stones/renal calculi treated?
Lithotripsy (laser shattering)
Ureteral stents
Alkalizers/diuretics
125
What is Crystalluria?
Excess crystal formation (e.g., oxalate) in acidic urine
126
Define these conditions:
Renal Aplasia
Renal Dysplasia
Renal Hypoplasia
Aplasia = no kidneys
Dysplasia = malformed
Hypoplasia = small kidneys
127
Can kidneys regenerate?
No; damage = chronic failure → dialysis or transplant needed
128
Where is the right kidney located compared to the left?
2 cm lower, in lumbar region
129
What is creatine and what is its function?
0.7–1.3 mg/100 mL blood
Straight chain compound
Phosphorylated to creatine phosphate (energy storage in muscle)
130
What is creatinine and why is it important?
Cyclic compound
Filtered by kidney, not reabsorbed
Used to calculate eGFR
131
What are the ideal properties of a substance to measure GFR?
Freely filtered
Not reabsorbed
Not secreted
(e.g., Inulin)
132
What are the main functions of the kidneys?
Removal of nitrogenous waste
Regulate electrolyte balance
H2O balance/volume
secrete erythropoietin
----------------------
Maintain blood pH
Regulate blood pressure (aldosterone, adh, angiotension)
Eliminate drugs/hormones
Activate Vitamin D3
Perform gluconeogenesis (when glucose made from non-carbhydrate (maybe when hungry)
133
How do kidneys regulate electrolyte balance?
Nephrons use countercurrent exchange
Reabsorb: sodium (Na⁺), bicarbonate (HCO₃⁻), calcium (Ca²⁺)
Secrete: potassium (K⁺), acidic ions
Excrete: phosphate, sulfate, toxins, antibiotics, conjugated hormones
134
How do kidneys regulate body water volume?
Adjust water reabsorption through nephrons
ADH (antidiuretic hormone) controls water retention
No ADH → diuresis (more water loss in urine)
Diabetes Insipidus = lack of ADH (urine has no sugar, just lots of water)
135
How do kidneys help maintain blood pH?
Buffer system: CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻
Use intercalated cells in collecting ducts:
Type A (acidosis): secrete H⁺, retain HCO₃⁻
Type B (alkalosis): secrete HCO₃⁻, retain H⁺
136
What hormones help kidneys regulate blood pressure?
Aldosterone: retains Na⁺ → water retention
ADH (vasopressin): retains water
Angiotensin II: vasoconstriction to raise BP
137
What happens when there's hypoxemia (low oxygen in the blood )?
Kidneys secrete erythropoietin
Stimulates red blood cell (RBC) production in bone marrow
138
How are drugs, antibiotics, and degraded hormones eliminated by the kidneys?
Through tubular secretion
These substances are not reabsorbed
139
How do kidneys activate Vitamin D3?
Cholesterol → 25-OH-Cholecalciferol (inactive form)
In kidneys: 1α-hydroxylase → 1,25-Di-OH-Cholecalciferol (active Vitamin D3)
Active Vitamin D3 helps absorb calcium in intestines
140
What is gluconeogenesis in the kidneys?
Making glucose from non-carbohydrates like proteins
Amino acids → glucose
Occurs in liver and kidneys during stress or starvation
