Urinary system Flashcards by laura amarin

Give x2 functions of the kidney

Production of urine through selective reabsorption and filtration.
Endocrine function

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Which part of the kidney is more well perfused?

The cortex.

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Name x5 landmarks within the kidney

The medulla, cortex, fibrous capsule, minor calyces, major calyces.

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Which structure sits on top of the kidney?

The adrenal gland (suprarenal gland)

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Where is the Loop of henle found in the kidney?

Within the medulla of the kidney

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What type of molecules are filtered?

Molecules <50, 000 MW.

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If substances are going to be absorbed from the kidney back into the blood, where will they be absorbed from?

The Proximal convoluted tubule.

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Where is urine concentrated?

The collecting duct

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What is the renal corpuscle?

The glomerulus + Bowman’s capsule

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What is the glomerulus?

Bundle of fenestrated capillaries.

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What does the ‘filtration barrier’ consist of?

Fenestrated capillary endothelium
Specialised basal lamina
Filtration slits between podocyte foot processes

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Which part of the kidney adjusts ion concentration of Na+, K+, H+, NH4+?

The distal convoluted tubule.

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Name x2 adaptations of the kidney for absorption.

Many mitochondria (Ascending loop of henle)
Many vesicles.
Brush border has a large surface area

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The proximal convoluted tubule absorbs approximately how much of glomerula filtrate?

70%

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The PCT has what type of epithelium?

Cuboidal with fairly tight junctions.

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Which part of the kidney contains a larger amount of aquaporins?

The PCT.

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Name x2 structures you would find many of in the PCT

Mitochondria

Aquaporins

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Describe the extracellular fluid surround the kidney tubules.

Hyperosmotic.

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Why is the structure of the descending loop of henle thinner and shorter than the ascending loop of henle?

Most transport of substances which occurs is passive. Fewer mitochondria. More aquaporins; movement is passive. Ascending loop of henle has less aquaporins; more pumps.

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Compare the structure of the descending and ascending loop of henle.

Descending loop of henle: simple squamous epithelium, aquaporins
Ascending loop of henle: cuboidal epithelium, water impermeable tight junctions, few aquaporins, many mitochondria.

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What is a hyperosmotic solution?

A solution with a greater concentration of solutes = draws water; lower water concentration.

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Water being reabsorbed back into the blood has what effect on. the blood?

Blood becomes more concentrated

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Describe the epithelium of the collecting duct.

Simple cuboidal epithelium.

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Where does renin come from?

The Juxtaglomerula apparatus.

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Where is the macula densa?

In the Distal convoluted tubule.

Are the kidneys intraperitoneal or retroperitoneal?

Retroperitoneal

At which level does the right kidney's superior pole sit in relation to the left kidney?

Right kidney = lower down - 11intercostal space | Left kidney = 11th rib

Kidney needs a large blood supply. It takes what percentage of resting CO?

20-25%

What drives ultrafiltration by the glomerulus?

Blood pressure

Which renal artery is longer the left or the right?

The right renal artery is longer than the left beause the aorta lies to the left of the midline.

Where are the three constrictions of the ureters?

pelviureteric junction, where ureter crosses pelvic brim and entrance to the bladder

What is the relevance of the 3 constrictions on the ureters?

Where renal stones may try to pass and cause renal colic

Which way do the apex and the base of the bladder face?

``` Apex = anterior Base = posterior (think about it!) ```

What is urothelium?

Transitional epithelium

Does the bladder membrane have a high or low permeability?

Low permemability

What is a trigone?

The triangular structure in the bladder made by the two entrances from the ureters and the exit to the urethra.

What is the name of the ligament which wraps around the urethra?

Pubovesical ligament = holds urethra in place.

Where is the external sphincter found?

Within the perineal membrane

Describe the two urinary sphincters

Internal sphincter = smooth muscle, purely reflex | External sphincter = striated muscle, can control partly voluntarily

Which nerve do we inhibit to urinary voluntarily?

The pudendal nerve which derives from s2, s3 and s4.

The internal sphincter is in between which two structures in males?

The bladder and the prostate.

How will urine be expelled?

``` Bladder fills Stretch receptors +Parasympathetic nerve (pudendal nerve) Contraction of the detrusor muscle relaxation of the internal sphincter ```

What are the names of the nodes in ureters which allow for lymphatic drainage?

Para-aortic nodes. | Lymph flows in opposite direction to blood.

The glomerulus is permeable and impermeable to which substances?

Permeable to small solutes and fluids | Impermeable to proteins and cells.

Define the term freely filtered

Solutes have the same concentration in the filtrate as in the plasma.

What may be seen in the urine in gallstones, cirrhosis or hepatitis?

Bilirubin

What may be seen in the urine in glomerula damage and nephrotic syndrome?

Protein

What may be seen in the urine in kidney stones, tumours and glomerulonephritis?

Blood

When will Urobilinogen be seen in the urine?

Haemolysis, cirrhosis and hepatitis

What will urine be like in diabetes insipidus?

Very dilute

Why is it important to get a midstream sample of urine (MSSU)?

To avoid contamination from bacteria in or around the urethra.

Why do you think it is important to immediately replace the lid on the urine dipstick test strips container?

Prevents reagents on the strips reacting with air.

Polycystic kidney disease is inherited. True or false.

True.

Why is protein seen in the urine in glomerula damage?

Proteins are very large and could only get into the urine if the glomerula is damaged.

What will you see mainly in the urine in alcoholics

Excess bilirubin

What is specific gravity?

Measures concentration of urine. High specific gravity = very concentrated urine. Low specific gravity = very dilute urine.

What may cause a low specific gravity of urine?

Individual has consumed a lot of water | Very dilute urine - as in Diabetes Insipidus.

Name one sign other than colour of urine in kidney infection

Cloudy urine

Osmolarity depends on which more - the number or nature of the particles?

Number

What percentage of ultrafiltrate is reabsorbed?

99%

Glomerula filtration is what kind of process?

Passive

Na2HPO4 has how many mosmoles/L?

3mosmoles/L

Reabsorption can occur through which mechanisms of transport?

Paracellular and transcellular

What type of molecules require proteins on the membrane to pass through?

Hydrophilic molecules

We do not have pumps for which 2 molecules transported in the kidneys?

Urea and H20; move massively through transpoters.

Water can move through which two molecules?

Tight junctions (paracellular pathway) and aquaporins (transcellular pathway).

Describe the distribution of solute reabsorption as you move down the nephron

60-70% in PCT 25% in Loop of Henle 8% in DCT <5% IN CD

What is the key energy driver for most transporters to function in the kidney?

Low intracellular calcium

Describe the difference in epithelium type in the descending LoH compared with the ascending LoH.

Descending LoH: Squamous | Ascending LoH: Cuboidal

Describe the nature of fluid once it leaves the Loop of Henle.

Becomes hypo-osmolar compared with plasma; water and salts have been heavily reabsorbed.

What is the mechanism behind Furosemide?

Blocks triple transporter: Na+/Cl-/K+.

Thiazide works through which mechanism?

Blocks the Na+/Cl- symporter. Raises plasma calcium concentration, lowers iCa2+.

Why do the DCT and CT require Vasopressin?

Would otherwise be impermeable to water as ADH inserts aquaporins (AQ-2) in the apical membrane.

Which are the two cells of the collecting duct?

Intercalated cells: Regulate acid-base balance | Principal cells: Regulate Na+/K+/water movement.

Describe the relationship between the Na+/glucose symporter and the Na+/K+ ATPase pump

The Na+/glucose symporter is passive and as both go into the cell, drives an electrochemical gradient for Na+ to leave cell via Na/K+ ATPase pump (active), bringing K+ into the cell. Transport from the Na+/K+ ATPase pump is therefore secondary.

How does Na+ leave the ascending LoH compared with Cl-?

Na+ leaves passively | Cl- leaves actively.

We know that normal GFR is 120ml/min, but what is the normal range?

90-150 ml/min.

After the age of 40, what happens to the GFR?

Declines by 10ml/min every decade.

What are the three components of Inulin which make it a suitable marker of GFR?

- Not reabsorbed - Not secreted - Freely filtered at the glomerulus

Carbonic anhydrase has what affect on sodium reabsorption?

Increases Na+ reabsorption

Potassium is secreted by which cells in the collecting duct?

Principal cells

Name x2 K+ sparing diuretics

- Amiloride = blocks Na+ channel | - Spirinolactone = aldosterone antagonist.

Furosemide is what type of diuretic?

Loop diuretic

ACE inhibitors can cause....

Hyperkalaemia; x Ang II, x Aldosterone which usually works to excrete K+

How does do Macula densa cells cause renin release?

Detect low Na+ due to a decrease in Na+ entering through the Na+/Cl/K+ pump = macula densa cell becomes hypoosmolar = water leaves, cell shrinks. Produces PGE2 and NO = stimulates renin.

Where do K+ sparing diuretics act?

Collecting duct