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Human Structure & Function > How do we get rid of toxic waste? > Flashcards

How do we get rid of toxic waste? Flashcards

1
Q

Where do the kidneys lie and why does the right kidney lie lower than the left?

A
  • The kidneys lie behind the parietal peritoneum on the posterior abdominal wall on either side of vertebral column.
  • Right kidney slightly lower than left (due to liver).
  • Lumbar vertebrae and rib cage partially protect the kidneys.
  • Bean shaped and about the size of a fist (~130g).
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2
Q

What is the renal capsule, adipose tissue and renal fascia?

A
  • Renal capsule: fibrous connective tissue surrounding each kidney.
  • Adipose tissue: engulfs renal capsule and acts as cushioning.
  • Renal fascia: thin layer loose connective tissue, which anchors kidneys to posterior abdominal wall.
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3
Q

What is the Hilum, Ureter, Cortex & Renal columns?

A
  • Hilum: Renal artery and nerves enter and renal vein and ureter exit.
  • Hilum opens into renal sinus: cavity filled with fat and loose connective tissue.
  • Ureter: exits at the hilum; connects to urinary bladder.
  • Cortex: outer area.
  • Renal columns: part of cortical tissue that extends into medulla.
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4
Q

What is the Medulla, Renal Pyramids, Minor Calyces, Major Calyces & Pelvis?

A
  • Medulla: inner area, surrounds renal sinus.
  • Renal pyramids: cone shaped. Base is boundary between cortex and medulla.
  • Apex of pyramid is renal papilla, points toward sinus.
  • Minor Calyces: funnel shaped chambers into which papillae extend.
  • Major Calyces: converge to form the renal pelvis.
  • Pelvis: enlarged chamber formed by major calyces.
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5
Q

What is the Nephron, what are the parts and why does the blood enter the nephron?

A
  • Functional unit of the kidney
  • Parts of the nephron: renal corpuscle, proximal tubule, loop of Henle, distal tubule.
  • Blood enters the nephron for filtration. Filtrate/urine produced.
  • Urine continues from the nephron to papillary ducts, minor calyces, major calyces, renal pelvis and ureter.
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6
Q

What are the types of neurons?

A

-1.3 million nephrons in each kidney and range from 50-55mm in length.
o Juxtamedullary nephrons: The renal corpuscle located near the medulla. Long Loops of Henle which extend deep into the medulla (15%).
o Cortical nephrons: Renal corpuscle located nearer to the periphery of the cortex. Loops of Henle do not extend deep into the medulla (85%).

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7
Q

What is the Bowmans capsule, What is the glomerulus & what does blood/fluid enter

A
  • Bowman’s capsule: enlarged end of the nephron, double walled chamber. Filters the blood/fluid which then enters the proximal convoluted tubule.
  • Glomerulus: network/ball of capillaries.
  • Blood/fluid enters the glomerulus through afferent arteriole, exits through efferent arteriole.
  • Note the size difference Afferent is bigger than efferent = PRESSURE
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8
Q

What is a parietal & visceral layer in bowmans capsule?

A
  • Parietal layer: Outer layer. Simple squamous epithelium – becomes cuboidal in PCT.
  • Visceral layer: Inner layer. Specialised podocytes that wrap around the glomerular capillaries.
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9
Q

What is fenestrae, filtration slips, basement membrane & what occurs here?

A
  • Fenestrae: window-like openings in the endothelial cells of the glomerular capillaries.
  • Filtrations slits: gaps between podocytes.
  • Basement membrane: sandwiched between the endothelial cells of the glomerular capillaries and the podocytes.
  • Filtration occurs here.
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10
Q

What is proximal convoluted tubule, loop of henle, distal convoluted tubule & collecting duct?

A
  • Proximal convoluted tubule: filtrate drains from the Bowman’s capsule into the PCT.
  • Loop of Henle (nephron loop): each loop has a descending and ascending limb.
  • Distal convoluted tubule: shorter than PCT
  • Collecting ducts: large diameter. Extend through medulla towards renal papilla → ureter.
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11
Q

In terms of the histology what is the proximal tubule, loop of henle, distal tubule & collecting ducts?

A
  • Proximal tubule: Simple cuboidal epithelium with many microvilli. Active reabsorption of Na+2, K+ & Cl
  • Loop of Henle: Thick parts - simple cuboidal. Thin parts - simple squamous epithelium – for osmosis/diffusion.
  • Distal tubule: Simple cuboidal, and very few microvilli. Numerous mitochondria.
  • Collecting ducts: Larger in diameter, simple cuboidal epithelium.
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12
Q

In urine movement what forces urine through the nephron?

A

-Pressure forces urine through nephron

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13
Q

What moves urine from renal pelvis to kidneys, through what and what do the ureters enter the bladder through?

A
  • Smooth muscle in ureters: Peristalsis moves urine from the renal pelvis in the kidneys through the ureters to the urinary bladder.
  • Ureters enter bladder obliquely through trigone. Pressure in bladder compresses ureter and prevents backflow
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14
Q

What do the ureters do and what are they lined with?

A

-Bring urine from renal pelvis to urinary bladder. Lined by transitional epithelium

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15
Q

What is the urinary bladder & trigone?

A
  • Urinary bladder: hollow muscular container. Located in pelvic cavity posterior to symphysis pubis.
  • Trigone: interior of urinary bladder. Triangular area between the entry of the two ureters and the exit of the urethra.
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16
Q

What is the urethra and what is it lined with?

A
  • Urethra: transports urine from the bladder to the outside of the body. Internal urinary sphincter - Elastic connective tissue and smooth muscle prevent urine continuously flowing out of the bladder.
  • Lined with transitional epithelium (top) stratified columnar epithelium (external opening).
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17
Q

What is the external urinary sphincter, what does it act as? Describe the male & female urethras

A
  • External urinary sphincter: skeletal muscle surrounds urethra as it extends through pelvic floor. Acts as a valve that controls the flow of urine
  • Male urethra: extends from the inferior part of the urinary bladder through to the tip of the penis.
  • Female urethra: shorter; opens into vestibule anterior to vaginal opening
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18
Q

What are the functions of the renal system?

A

1) Excretion: get rid of waste products. Urine production occurs in the kidneys via filtration of the blood and reabsorption of nutrients. Metabolic wastes and toxic molecules are excreted in urine.
2) Regulate blood volume and blood pressure – control extracellular volume by producing large amounts of dilute urine or small amounts of concentrated urine.
3) Solute (Cl- , Na+ , urea) concentration in the blood, extracellular pH, red blood cell synthesis, vitamin D synthesis

19
Q

Function of the kidneys, nephrons & what are the stages of urine production?

A
  • Kidneys: regulate body fluid composition. Sorts chemicals in the blood for removal or for return into the blood.
  • Nephrons: the structural component of the kidneys that ‘sorts’ the blood.
  • Urine production: 3 stages – filtration, tubular reabsorption, tubular secretion.
20
Q

What is filtration?

A

-Movement of fluid, derived from blood flowing through the glomerulus, across filtration membrane.

21
Q

Define filtrate, renal fraction and glomerular filtration rate

A
  • Filtrate: water, small molecules & ions that can pass through membrane. Doesn’t include red blood cells, proteins or large molecules.
  • Renal fraction: part of total cardiac output that passes through the kidneys. Varies from 12-30% in a healthy resting adult.
  • Glomerular filtration rate (GFR): amount of filtrate produced each minute – 125ml/minute. 180 L/day.
22
Q

What is the average urine production per day?

A

-Average urine production/day: 1-2 L.

23
Q

What does filtration do?

A
  • Most of filtrate (99%) must be reabsorbed

- Removes toxins quickly from blood

24
Q

What are fenestrae, filtration slits & basement membrane in the renal system?

A
  • Fenestrae: window-like openings in the endothelial cells of the glomerular capillaries.
  • Filtrations slits: gaps between podocytes.
  • Basement membrane: sandwiched between the endothelial cells of the glomerular capillaries and the podocytes.
25
Q

What is the filtration membrane and what are podocytes?

A

-Filtration membrane: filtration barrier (7nm). It prevents large molecules, blood cells and proteins from entering the lumen of Bowman’s capsule.
o Podocytes, basement membrane and endothelium

26
Q

What does filtrate include?

A
  • Filtrate includes: Water, glucose, fructose, amino acids, urea, urate ions, creatinine, Na+ , K+ , Ca+2 , Cl-.
  • Very little protein normally found in filtrate and urine. Filtration is driven by blood pressure.
27
Q

What is filtration pressure?

A

Filtration pressure: pressure gradient responsible for filtration; forces fluid from glomerular capillary across membrane into lumen of Bowman’s capsules.

28
Q

What forms the wall of the afferent arteriole?

A
  • Smooth muscle cells from the wall of the afferent arteriole – juxtaglomerular cells.
  • And specialized tubule cells from the DCT – macula densa.
29
Q

What do the cells of the afferent arteriole secrete and what does it do?

A

-Secrete renin – enzyme – filtrate formation and blood pressure.

30
Q

What is tubular reabsorption, when does it occur & what happens?

A
  • Tubular reabsorption: the return of water, small molecules & ions to the blood.
  • Occurs as filtrate flows through the lumens of the renal tubules.
  • Substances are reabsorbed into interstitial fluid and into circulation via peritubular capillaries.
31
Q

What substances are absorbed in tubular reabsorption?

A

-Substances: Amino acids, glucose, fructose, Na+2, K+ , Ca+2 , Cl- , HCO3-

32
Q

In the proximal tubule what % of filtrate is reduced, what is in the filtrate, what is apical & basal surface?

A 
-Proximal tubule: Majority. 
o	Reduced filtrate down to ~35%. 
o	Water (osmosis). 
-Apical surface: out of nephron lumen. 
-Basal surface: into body (blood).
33
Q

In the loop of henle describe its structure, what is reabsorbed, how much is the filtrate reduced to and how are the ions moved across the membrane?

A

-Loop of Henle: Thin part – simple squamous epithelium
o Further reabsorption of water and some solutes (osmosis – high concentration of solutes in medulla)
o Reduced filtrate down to 20%.
-Ions= Diffusion, Active transport & Symport

34
Q

In the distal tubule & collecting duct what is controlled here, what do these do and what is reabsorbed?

A

-Distal tubule & Collecting ducts: Hormonal control (Anti Diuretic Hormone)
o ADH – makes tubule wall permeable to water – water moves out of filtrate back into body – small concentrated urine.
o Some reabsorption of water (osmosis) and ions
o Ions - Na+ , Cl- , H+ (Active transport & Symport).

35
Q

In the proximal convoluted tubule what transports sodium across what membrane and describe the concentration of sodium in and out of the nephron cell??

A
  • Active transport of Na+ across the basal membrane from cytoplasm to interstitial fluid linked to reabsorption of most solutes
  • Concentration of Na+ is low inside the cell and Na+ moves into nephron cell from filtrate through the apical membrane. Other substances move by symport.
36
Q

What is tubular secretion, where does it occurs and is it active, passive or both?

A
  • Tubular secretion: The movement of non-filtered substances, toxic by-products of metabolism, drugs or molecules not normally produced by the body, into the nephron for excretion.
  • Occurs mainly in the distal convoluted tubule.
  • As with reabsorption it can be active or passive.
37
Q

What is Ammonia?

A

-Ammonia: is a toxic by-product of protein metabolism. Diffuses into lumen of nephron. H+ , K+ and penicillin: actively secreted into nephron

38
Q

What forces urine through the nephron and what forces it through ureters?

A
  • Hydrostatic pressure forces urine through nephron
  • Peristalsis moves urine through ureters from region of renal pelvis to urinary bladder. Occur from once every few seconds to once every 2-3 minutes
39
Q

What does the para & sympathetic NS stimulation do in urine movement and how does urine enter?

A
  • Parasympathetic stimulation: increase frequency
  • Sympathetic stimulation: decrease frequency
  • Ureters enter bladder obliquely through trigone. Pressure in bladder compresses ureter and prevents backflow
40
Q

What is the % of filtrate in urine per day, what can urine be and what is in urine at the end?

A
  • 1% of filtrate and 1-2L per day
  • Water Dilute or concentrate – depending on body needs (ADH & Renin)
  • Urea, uric acid, ammonia, creatinine, H+ , K+ Bile pigments
  • Drugs and Toxins: Penicillin & morphine
41
Q

What is the flow or urine form ureters to bladder & bladder to urethra and what is the bladders capacity?

A
  • Flow of urine from ureters to bladder is continuous – bladder to urethra is not.
  • Bladder capacity: max 1L.
42
Q

What is the elimination of urine from the bladder called?

A

-Elimination of urine from the bladder is called micturition.

43
Q

Describe the process of elimination when the bladder is full

A
  • Full bladder activates stretch receptors – sends message to CNS.
  • Brain voluntarily controls the external urinary sphincter.
  • External sphincter relaxes – urination.

Human Structure & Function (11 decks)

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