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Physiology 2nd Smester > Urine Formation L13 P1 > Flashcards

Urine Formation L13 P1 Flashcards

1
Q

What is the Urine and what its consist of ?

A
  • Urine is liquid by-product of metabolism produced by kidneys
  • its primarily consist of water (91-96% ) with a lot of different
  • non orgainc
  • organic
    Components
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2
Q

What is the Organic components of Urine ? g/L

A
  • Urea :25-30
  • Uric acid : 0.5 - 0.8
  • Creatinine :1.0 - 1.5
  • orgainc sulphate
  • Amino acid - trace amount
  • Urobilinogen
  • Nitrogen : 0.3 -1.2
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3
Q

What may result if consumption of meat in the body ?

A

Increase consumption of meat may increase Uric acid in Urine up to 3 g/L

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4
Q

What is the non - Organic components of Urine ? g/L

A
  • Chloride 10-15
  • Sulphate 1-2
  • Calcium 0.1 - 0.3
  • Sodium 3-5
  • Potassium 0,8 -1.3
  • inorgainc phosphate 0.8-1.3
  • Ammonia 0,7-0,8
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5
Q

Where is the site of Urine formation ?

A

Nephrons

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6
Q

Types of Nephrons And there function ?

A

1-Cortical

  • they comprise 85-86 % of the nephrons in the kidneys
  • its plays a major role in excretion of waste products in dissolved form in the urine

2- Juxta-medullary

  • they comprise 14-15% of the nephrons in the kidney
  • not take a part in urine formation and play a major role in regulatory mechanism of blood pressure changes
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7
Q

What parts of Nephron ?

A

1-Malphigian corpuscle , Glomerulus , bowmans cup
2- Proximal convulated Tubule (PCT)
3-loop of henle
4-Distal comvulated tubule ( DCT )

— collecting duct ( not part of the nephron )

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8
Q

What is the Urine formation phases ?

A

1- Glomerular filtration : creates a plasm like filter of the blood

2-Tubular reabsorption : removes useful solutes from the filtrate and returns them to the blood

3-tubular secretion : removes additional wastes from the blood adds them to the filtrate

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9
Q

Explain the first phase ( glomerular filtration )

A
  • Glomerular filtration is the passive transport of plasma with its dissolved small solutes from glomerular capillaries into Bowmans capsule and further to proximal convulated tubule
  • the resultant is fluid is known as glomerular filtrate or ultra filtrate or primary urine

-this process of filtration occurs in Malpighian corpuscle
Bowman capsule and glomerular together constitute the malphigian corpuscle

-1- Bowman’s capsule
- its the initial dilated part of nephron
- its forms the filtration membrane
- it has two layers : visceral and parietal
— the space between visceral and parietal layer is called bowmen space , here the glomerular filtrate enter and continues into PCT

-2- Glomerulus
: its formed by invagination of a tuft of capillaries into the bowmans capsule, it has an extremely thin membrane and is made up of 3 layers
-layer 1 : padocytes cells , Visceral Epithelium covering the capillaries, its not continuous, its gives series of process called pedicels interdigiting upon capillary surface to form : filtration slits ( lacuna ) along the capillary wall
-layer 2 : besment membrane
-layer 3 : endothelial cells , the endothelial layer of glomerular capillaries is fenestrated with pores of 100 nm , ( this feature allow the plasma filtration with retention of plasma protein and blood cells

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10
Q

NB ! Glomerular capillaries maintain a pressure of 70 mmhg , while all other systemic capillaries have pressure of 20-30mmhg , how it achieve larger pressure then others ??

A

In glomerular capillary the afferent arteriole has larger diameter than the efferent one , this deference creates high pressure in glomerular capillaries up to 70 mmhg than other systemic capillaries which has 20-30 mmhg pressure

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11
Q

Renal arteriol network also known as Magical capillary network , because it form two plexus what are they ?

A

1- glomerular capillaries ( plexus ) : it is formed by afferent arteriol and drains into efferent arteriol

2- Peritubular capillaries ( plexus ) or vasa recta : its formed by efferent arteriol round PCT

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12
Q

What are the forces that causing Filtration ?

A

1- glomerular hydrostatic pressure: its constitute. Filtration force driving fluid out of the glomerular capillaries and into bowmans capsule

2- Ultrafiltrate hydrostatic pressure: hydrostatic pressure of ultrafiltrate in the bowmans capsule , it opposes filtration

3- glomerular oncotic pressure: colloidal osmotic pressure of the plasma in the glomerular capillaries bringing fluid into glomerular capillaries

—- Formula :
- Filtrate pressure (pf) = glomerular hydrostatic pressure (P h/g) — Ultrafiltrate hydrostatic pressure ( P h/u ) — glomerular oncotic pressure ( P onc. )

  • Pf = P h/g — P h/u — P onc

If we put norm values of these
Pf = 70-20-30= 20 mmhg

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13
Q

How much the pressure of filtrate pressure ?

A

20 mmhg

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14
Q

How much the pressure of glomerular hydrostatic pressure ?

A

70 mmhg

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15
Q

How much the pressure of Ultrafiltrate pressure ?

A

20 mmhg

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16
Q

How much the pressure of glomerular oncotic pressure ?

A

30mmhg

17
Q

What is the Similarities and difference between primary urine and blood

A

– Similarities
Since most of the substance in the plasma except the proteins are freely filtered thus it is identical with plasma in :
1- osmolality
2- pH
3- electrical conductivity
4- concentration of small molecules such as glucose, urea , creatinine
— Differences :
Primary urine dose not have proteins and formed elements ( RBC , WBC , platelets ) while in blood they are present .
- content of primary Urine is close to serum but without much of proteins
- thus Serum : is part of blood without RBC , WBC , platelets or clotting factors and large proteins .

18
Q

Explain the phase 2-Reabsorption

A
  • Reabsorption : means the transport of solutes and water from tubular lumen into peritubular capillaries.
  • kidney uses active and passive kinds of transport for the process of reabsorption

1- Passive transport : in the passive transport substances move across the cell membrane without any energy expenditure by the cell due to some gradience presence , and these gradience is :
1- Diffusion : is a passive process by which molecules move from areas of high concentration to area of low contraction
- and it consist of 2 types :

1- simple diffusion : is movement if substance from region of higher concentration to region of lower concentration, ions utilize ionic channels to cross the cell membrane, some channels are continuously open while other are gates Ex/ diffusion mechanism is available for sodium ion to pass through the tight junction of PCT cells in association with chloride ions
2- Facilitated diffusion : it is a carrier mediated process that enables molecules that are too large to flow though membrane channels by simple diffusion, facilitated diffusion of glucose

2-Osmosis : flow of solvent water across a selectivity permeable membrane from a region of lower solute concentration to higher solute concentration, by this water follows the sodium ions

3- filtration : it occurs due to the presence of hydrostatic gradient , the pressure of the primary urine is slightly higher than that one of blood in capillaries of PCT

4- Electrostatic diffusion : cations attract to negatively charged ions and vice versa

—2 Active transport: in active transport substance are transported against their chemical and electrical gradient , this form of transport requires energy in form of ATP
- active transport consist of 2 types
1- Primary active transport: they directly use energy obtained from hydrolysis of ATP , Ex sodium- potassium pump

2- secondary active transport: secondary active transport uses the energy stored by primary active transport to drive across the membrane some other substance
- sodium ion is transporting by primary active transport, but its transposing in sodium- potassium pump is able only in the situation of its connecting in triads with one molecule of glucose and one aminos acid , so in this case glucose and amino acid went by secondary active transport

19
Q

How the substance are reabsorbed

A
  • all substances including harmful ones are reabsorbed passively
  • there are active forms of transport for the return of the substance useful for the body from primary urine
  • the only substance thats reabsorbs only passively is water
20
Q

Explain the 3- phase Secretion

A
  • secretion : refers to the transport of solutes form peritubular capillaries into tubular lumen , it is an active process
  • Substances secreted back from capillaries to final urine are (protons, non-volatile acids , potassium ions , toxins , some drugs like penicillin as well as hydronium ions , bile salts oxalates , urates ,)
  • after secretion final urine is formed which then passes to collecting duct and further to renal pelvis , urtere and urinary bladder
21
Q

Explain the Urinary bladder

A
  • Urinary bladder is a hollow muscular organ that collect and stores urine till micturition
  • micturition : release of urine from urinary bladder via urethra to the outside of the body

Physiology 2nd Smester (13 decks)

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