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Flashcards in The Urinary System Deck (59):

What are the 4 structures of the Urinary System:

1) 2 Kidneys (with adrenal glands)
2) 2 Ureters
3) 1 Bladder
4) 1 Urethra


What it the location and function of the kidney?

Location = Posterior to the abdominal wall and underneath the diaphragm
Function = To secrete urine


What is the function of the 2 ureters?

To transport the urine from the kidneys to the bladder by peristalsic contractions (intothe 2 orifices in the trgone of the bladder)


What is the function of the bladder?

To temporarily store urine and MICTURITION


How much urine is normally stored in the bladder?

250 - 300ml.
500ml = painful.


What are the 3 layers of the bladder called?

(inside - out)
1) Mucous layer
2) Muscular
3) Serosa


What is the 'TRGONE' in the bladder?

3 orifices that made a triangle.
2 open up to the ureters and 1 opens up to the urethra


What is the function of the urethra?

To transport the urine to the outside world.


Why is the urethra different in the male and female?

Male is longer and female's is shorter. The males has both a urinary and reproductive function, whereas the female's only has a urinary function.


Describe the process of micturition?

1) 200ml of urine in the bladder stimulate the stretch receptors.
2) Impulses are sent via the afferent pelvic nerve to the sacral region of the spinal cord.
3) An interneurone, sends information to the thalamus and then to the cerebral cortex.
4) Information is then send down the efferent pelvic nerve to the DETRUSOR MUSCLE.
5) The detrusor muscle is stimulated to contract.
6) Elimination of urine (micturition) will only occur when the external urethral sphincter relaxes.


Describe the Gross Structure of the Kidney?

1) Renal Capsule (Fibrous Outer Layer)
2) Renal Cortex
3) Renal Medulla (organised in striations to form the renal pyramids - that contain the nephrons)
4) Renal Papilla
5) Minor Calyx
6) Major Calyx
7) Renal Pelvis that is continuous with the ureter (thin smooth muscle wall)


How will the smooth muscle in the renal pelvis contract?

Pacemaker cells in the calyces (minor and major calux) will initiate the impulses for the smooth muscle to contract.


What is the functional unit of the kidney and where is it contained?

The nephron - in the renal pyramids (of the renal medulla).


Describe the components of the nephron:

1) Glomerular capsule/Bowman's Capsule (contains the glomerulous - network of arterial capillaries)
2) Proximal convoluted tubule
3) Loop of Henle
4) Distal convoluted tubule
5) Collecting duct


What happens at the end of each collecting duct?

Collecting ducts from other nephrons will join together in order to form larger ducts and urine is taken from these ducts, down the minor/major calyces and into the renal pelvis (that is continuous with the ureter)


What are the 4 functions of the kidney?

1) Simple Glomerular Filtration = Blood is filtered from the glomerulus in the glomerular capsule and a plasma-like filtrate is formed.
2) Selective tubular absorption = useful substances are absorbed back into the blood.
3) Tubular secretion = Unwanted substances are taken into the tubules.
4) Water conservation = Water is absorbed back into the blood.


Describe the blood supply to and from the kidney:

1) Aorta
2) Renal artery
3) Afferent renal arteriole
4) Glomerulous
5) Efferent renal arteriole
6) 2nd cappilary bed (supplies the nephron with O2 and nutrients)
7) Renal Venule
8) Renal Vein
9) INFERIOR vena cava


What nerve supply controls the kidneys?

Autonomic Nervous System


What occurs in simple glomerular filtration?

The blood in the glomerulous is filtered and taken in to the glomerular capsule - forming a PLASMA-LIKE FILTRATE.


What 2 things aids glomerular filtration?

1) The walls of both the glomerulus and glomerular capsule are thin and semi-permeable.
2) Pressure differences between the plasma in the glomerulus and the plasma-like fluid in the glomerular capsule.


What substances can NOT pass though into thee filtrate, during simple glomerular filtration?

1) Plasma proteins
2) Thrombocytes
3) WBC's
4) RBC's
5) Some drugs


Describe the filtration membrane of glomerulous (What the blood needs to be filtered through before going into the glomerular capsule)

(inside - out)
1) Cappillary endothelium (with fenestrations)
2) Basal Lamina
3) Podocyte cell body
4) Pedicels (produced by the podocyte cells)
5) Filtration slits (inbetween the pedicels)


What does the GFR tell us?

How much filtrate is being produced by BOTH of the kidneys in simple glomerular filtration/ per min


What is the equation for GFR?

urine concentration (U) x volume of urine (V) divided by the plasma concentration (P)


What are the average GFR for females and males?

Females = 115ml/min
Males == 125ml/min


What 2 things allow for the Auto-Regulation of the GFR?

1) Pressure changes in the renal artery/arterioles
2) Changes in the concentration of plasma metabolities


What occurs in the Tubular Selective Reabsorption process, where does it occur and what is the importance that it occurs?

1) The filtrate in the tubules is altered in terms of its volume and composition.
2) It occurs in the kidney tubules (apart from the glomerular capsule)
3) To take useful substances back into the body in order to maintain the balance of electrolytes, fluid and pH levels.


Describe selective reabsorption in the Proximal Convoluted Tubule?

Sodium - 65%
Water - 65%
Glucose - 100%
Amino acids - 100%


What is it called if glucose is found in the urine and what does this mean?

Glucosuria. It means there would have been excess amounts of glucose in blood to start off with.


Describe selective reabsorption in the Loop of Henle?

Sodium - 25%
Water - 25%


What protein transporter is contained in the Loop of Henle which causes urine to be concentrated on a hot day?

Sodium Potassium 2 Chloride Transporter


Describe selective reabsoption/ secretion in the Distal Convoluted tubule and the collecting duct?

Sodium - 8-10%
Water - 8-10%
Potassium secretion into the tubule


Why does tubular secretion take place?

As when the filtrate is formed in glomerular filtration, there is only a short amount of tie that blood in the glomerulus travels through the glomerular capsule.


What is an important secretion that takes place in the kidneys?

H+ for acid-base balance


What are the 7 different functions of the kidney (FEAREDU)?

1) Body Fluid Regulation
2) Body electrolyte Regulation
3) Acid- base balance (through the secretion of protons)
4) Renin production
5) Erythropoietin (stimulates RBC's to be produced from red bone marrow)
6) Activation of vitamin D (by producing calitriol - that activates vitamin D into active metabolites)
7) Urine production (important for removing metabolic waste products and toxins from the body)


Describe the appearance of urine:

Colorless. The yellow colour is due to the UROCHROME (produced by the breakdown of haemoglobin)


What causes the urine to smell?

The longer urine is left, the longer it will smell. As the longer time bacteria has to break down and produce ammonia.


What is the pH of urine?

Slightly alkaline - due to the H+ ions secreted in the urine (for acid-base balance)


What is the osmalility?

50 mmol/kg to 1200 mmol/kg (in a very dehydrated person)


What is the percentage of water and solute in the urine?

Water = 95%
Solute = 5%


How is carbonic acid produced?

In the proximal convoluted tubule, H+ are secreted into the filtrate. In the filtrate the H+ will mix with bicarbonate in order to form carbonic acid.


How is phosphoric and sulphuric acid produced?

Catabolism of organic products (meat and proteins)


How is organic acid produced?

Fatty acid metabolism


How is lactic acid produced?

Anaerobic respiration


What is the equation for carbonic acid?

CO2 + H2O = carbonic acid = H+ + HCO3 (bicarbonate)


What makes the blood more acidic and what makes it more alkaline?

Acidic = CO2
Alkaline = Bicarbonate


What are the accepted pH levels of the blood?

6.8 - 8 (slighlty acidic)


What is the lung's role in maintaining a blood pH of slightly acidic?

To excrete CO2 from the blood (which would normally make the blood acidic)


What is the kidney's role in maintaining a blood pH of slightly acidic?

(in the Proximal Convoluted Tubule)
1) H+ are secreted into the filtrate from the carbonic acid in the blood (so that bicarbonate ions remain)
2) Bicarbonate ions are reabsorbed into the blood from the filtrate
3) Ammonium ions are secreted into the blood from the filtrate (as this encourages bicarbonate formation)


What is acidosis?

When there is an excess acid pH of the blood
(7.35 pH)


What is alkalosis?

When there is an excess alkaline pH of the blood
(7.45 pH)


Which part of the kidney is involved in correcting the blood pH in acidodis or alkalosis?

The intercalated cells in the collecting duct of the kidney tubule.


What collecting tubule cells are responsible for correcting the blood pH in acidosis? (make more alkaline)

Type A Intercalated cells =
1) H+ are secreted into the filtrate from the carbonic acid in the blood (so that bicarbonate ions remain)
2) Bicarbonate ions are reabsorbed into the blood from the filtrate
3) Absorb dihydrogen phosphate into the blood (which encourages the production of bicarbonate ions)


What collecting tubule cells are responsible for correcting the blood pH in alkalosis? (make more acidic)

Type B intercalated cells =
Secrete bicarbonate ions (from the carbonic acid in the blood) into the filtrate. Leaving H+ ions in the blood which make it more acidic.


Where in the kidney tubule is the balance of sodium and water under hormonal control?

The distal convoluted tubule and collecting ducts


Which 3 hormones control the absorption and secretions that occur in the distal convoluted tubule and collecting ducts - in order to maintain sodium and water balance?

1) ADH (Anti-diuretic hormone)
2) ANP (Atrial Naturetic peptide) - protein
3) Aldosterone - steriod


Describe the mechanism for ADH to be released?

1) Osmotic pressure in the blood increases (high electrolyte concentration)
2) Osmoreceptors in the hypothalamus detect this osmotic pressure and stimulate the posterior pituitary gland to release ADH
3) ADH will act on the distal convoluted tubule and the collecting ducts.
4) Water is absorbed back into circulation from the filtrate.


Describe the mechanism for ANP to be released?

1) Baroreceptors in the atrial arch detect high blood pressure.
2) Atrial myocytes release ANP.
3) ANP acts on the distal convoluted tubule and the collecting ducts - so secrete Sodium and water will follow.
4) Lowers blood pressure


Describe the mechanism for aldosterone to be released?

1) Low blood pressure in the renal blood flow.
2) Afferent arterioles (supplying the nephron) to release RENIN.
3) Renin will convert Angiotensinogen into angiotensin.
4) ACE will convert angiotensin into angiotensin 2.
5) Angiotensin 2 will cause vasoconstriction - increase the blood pressure.
6) Angiotension 2, together with high potassium plasma levels, stimulates the adrenal cortex (of the adrenal glands) to release ALDOSTERONE.
7) Aldosterone acts on the distal convoluted tubule and the collecting ducts to secrete potassium in exchange for the absorption of sodium.
8) As sodium is absorbed - water will follow.
9) Renal Blood pressure is raised