Urinary system Flashcards
What are the two parts of the renal corpuscle?
- Glomerulus and Bowman’s capsule
What is the role of the proximal tubule?
- Reabsorption
water
glucose
peptides - Secretion
70% Na+ removed by active transport
What is the loop of henle?
- Recovery of water
- Set up concentration gradient
- Divided into 2 limbs
ascending
descending
What is glomerular filtration rate?
- Amount of filtrate formed in all the nephrons of the kidneys per minute
- Depends on pressure gradient in the glomerulus
What is GFR of healthy adult?
125ml/min = 180L/day
What are the 6 functions of the kidney?
- Regulation of extracellular fluid volume and blood pressure
- Regulation of blood osmolarity (300mOsM)
- Maintenance of ion balance(Na+, K+ etc)
- Homeostatic regulation of plasma pH (7.38-7.42)
- Excretion of metabolic and other waste
- Production of hormones
What is tubular reabsorption?
tubular lumen to peritubular capillary plasma
What is tubular secretion?
peritubular plasma to the tubular lumen
What is the definition and value of osmolarity?
concentration of combined solutes in water
in normal body fluid = 300mOsm/L
What is the difference between hyper-, hypo- and isotonic?
Hyper- water out, shirinkage
Hypo- water in, bursting
Iso- balance
What is the most important molecule to control?
Na+ as it controls the movement of water across the plasma membranes.
Water will follow the movement of sodium if that membrane is permeable to water.
What is countercurrent multiplication?
- reabsorbs water from the tubular fluid and concentrates urine
- This mechanism prevents the kidneys from producing litres and litres of dilute urine every day
What is tubular transport?
Two membrane surfaces
- Basolateral membrane (adjacentto interstitial fluid)
- Luminal membrane (adjacent totubular fluid)
From tubular filtrate into tubular cellalong concentrationgradient
Some substances require facilitated diffusion or carrier systems to cross basolateralmembrane
What is the transcellular route of tubular transport?
- Transport across the apical membrane
- Diffusion through cytosol
- Transport across the basolateral membrane
- Movement through interstitial fluid and into capillary
What is the paracellular route of tubular transport?
Movement through leaky tight junctions
Movement through interstitial fluid and into capillary
What is passive transport?
- movement ofsubstances within the cells along the concentration gradient
- does not require energy
- can involvetransmembraneproteins
How does the loop of henle work?
- Countercurrent multiplier system in Loop of Henle
- Countercurrent exchange in vasa recta
- Creates hypertonic renal medulla
What is countercurrent exchange?
Important component of countercurrent multiplier
Reabsorbs water inascending limb
Recirculates salt in interstitial fluid to maintain osmolarity
What are the differencess between the descending and ascending loops?
Descending - water permeable, not salt, osmotic loss of water concentrates salts in lumen
Ascending - thin segment; salt permeable, not water, salts diffuse out of lumen, thick segment; active Na+ and Cl- & K+ cotransport
How does ADH affect the nephron?
- increased glomerular filtration
- decreases thereabsorption of Na+and water
- inhibit Na+K+ ATPase
How does aldosterone affect the nephron?
- increases thereabsorption of Na+and water
- increases ENac
- activatesNa+K+ ATPase
What are the 5 factors affecting renal clearance?
- properties of the drug
- urine pH
- blood flow to the kidney
- biological factor ie. sex, age
- disease state
What is respiratory acidosis?
too much carbonic acid (pH too low)
What is respiratory alkalosis?
too little carbonic acid (pH too high)
What is dialysis?
- removes excess water and metabolic wastes from the body
- prevents chemicals such as K+, bicarbonate and Na+ from reaching hazardous levels
- used in severe renal failure
- less than 90% of kidneyefficiency
- GFR ofless than 15
What is the speed of urine formation?
> 1ml/min
How does urine get to the bladder?
Peristaltic contractions of ureter walls
What is the bladder capacity?
600-800ml
What is the main muscle of the bladder?
The detrusor
- composed of three layers of smooth muscle fibres
- fibres arranged differently in each (spiral, longitudinal, circular)
What is the difference between male and female urethras?
Male
- 18-20cm
- Two functions
Female
- 4cm
- Single function
What is voluntary micturition?
- Cortex, cerebellum and the micturition centre located in the pons
- Interneuron in the bladder signals to pons when it is full and to release
- Develops in early childhood; full control normally present at 3 to 5 years
What are the three simulataneous events of micturition?
- Contraction of detrusor muscles– involuntary
- Opening of the internal urethral sphincter – involuntary
- Opening of the external urethral sphincter - voluntary
What is urinary incontinence?
- Involuntary leakage of urine
- Control over urinary sphincters lost or weakened
- Treatment include exercise, bladder training, medication, medical devices and surgery
What are the four types of incontinence?
Stress - weak pelvic floor
Urge - involuntary muscle contraction
Overflow - blocked urethra
Neurogenic - nervous system
What causes UTIs?
- Bacteria ascend the urethra to the bladder
- More common in women
- 95% of cases caused by E.coli
- Symptoms include urgency, pain and increased frequency, lower back pain, fever, nausea
- Treated with antibiotics such as nitrofurantoin, trimethoprim and ciprofloxacin
What are bladder stones?
- Minerals in concentrated urine crystallize and form stones
- Can pass without treatment, but sometimes need surgical removal
- If left untreated may lead to infections and other complications
What are the symptoms of bladder cancer?
- Symptoms include blood in the urine, pain with urination and low back pain
- Treatments include surgery, radiation therapy,chemotherapy or immunotherapy
- Typical 5-year survival rate of 55%
