Urinary system Flashcards
Anatomy - the urinary tract
upper urinary tract
-kidneys
- Ureter
lower urinary Tract
- bladder
- Urethra
- Penis / vulva
urogenital system due to the shared anatomy
functions of the urinary system
Excrete waste - nitrogenous waste, excess water and products of drug metabolism
regulates - volume and chemical composition of body fluids
- porvides a series of tubes to conduct urine from the kidneys
- secretes erythropoietin
PCV
Packed cell volume
distribution of fluids
dry matter 40%
Body water 60%
Extra cellular fluid 20%
intra cellular fluid 40%
plasma 5%
intersitial fluid 15%
Kidney look
- bean shaped
-cranial abdomen - right kidney lies more cranial (left is left behind)
- in the retroperitoneal space
average size of a canine and feline kidney relates to approximately 2.5 lumbar vertebrae
renomegaly
enlarged kidney
what is a hilum
exit and entry point for blood vessels, and nerves (ureter exits here)
kidneys
- cortex red in colour
-medulla slightly paler - the kidneys are surrounded by a layer of fat for energy
- and a tough fibrous connective tissue for protection
the nephron
- functional units of the kidneys
cortex
contains the renal corpuscles and convoluted tubules of the nephrons
Medulla
triangular shaped pyramids containing ducts and between them tissue containing the loops of Henle
Renal blood supply
the renal arteries supply the kidneys
20% of blood is directed to the kidneys - high blood supply to filter the blood
blood then leaves via the renal vein
capsule
protective layer around the nephron
diffusion
movement of particles from high concentration to low
osmosis
movement of a solution towards a higher concentration of molecules
these molecules exert osmotic pull - many electrolytes (sodium and chloride) along with urea and glucose
Nephron works because of ?
- osmosis
- diffusion
- reabsoprtion
- secretion
5 key components of a Nephron
- Glomerulus
- proximal convoluted tubule
- loop of henle
- distal convoluted tubule
- collecting ducts
Glomerulus (Bowmans Capsule)
- a capsule surrounding a network of capillaries
- lined with podocyte cells
-high pressure forces fluid and smaller molecules out of the blood through the pores to carry on through the nephron
- larger molecules are retained in the blood
- known as ultrafiltration
Proximal convoluted tubule
- reabsorption and secretion starts
- simple cuboidal and columnar epithelium
- reabsorption of water, sodium and chloride
- reabsorption of glucose
- secretion of toxins and certain drugs
- concentration of nitrogenous waste e.g. urea and creatinine
loop of henle
- Urine concentration starts here, depending upon ECF dtermines what is reabsorbed and secreted
- descending is permeable to water allowing it to be reabsorbed
- ascending is permeable to sodium allowing for sodium reabsorption
Distal convoluted Tubule
some late adjustments made here
-last reabsorption of sodium and water
- secretion of potassium into the urine
Distal convoluted Tubule
- Regulation of blood pH (acid base balance)
- if blood pH falls (acidic) hydrogen excreted into the urine
- if pH rises (alkaline), the kidney retain the hydrogen ions
- too much hydrogen causes metabolic acidosis
Collecting Duct
- final adjustments (excretion of urea, creatinine, Na, Cl and excess H20)
ADH (antidiuretic hormone) from the pituaitary gland detrmines the permeability of the duct walls to water
- reatins h20 in blood (so concentrates the urine
Collecting duct
from the collecting ducts urine travels to the renal pelvis to the ureters leaving the kidney via the ureters out of the hilus of the kidney
Kidneys summary
- osmoregulation maintains the amount ‘salts’ retained by the body
- maintain water levels in the body
- regulate blood pH levels (via hydrogen loss/ retention)
- stimulate red blood cell production
- autoregulate blood pressure
RAAS (renin - angiotensin - aldosterone system)
- low blood pressure (hypotension) it fails to work as a filter
- hormones that increase blood pressure
- renin (from the kidneys) leads to vasoconstriction
aldosterone - (from adrenals) causes sodium retention
ADH - causes h20 retention
Ureters
- there are 2 ureters and they leave the kidneys via the hilus
- each is suspended by mesentry
- each are thin- walled muscular tubes and lined with transitional epithelium
-urine is formed in the kidney and carried out to the bladder by the ureters
Bladder
Trigone acts as a valve preventing backflow
- pear shaped organ lined with transitional epithelium
- sphincters control the movement into the next structure urethra
- internal sphincter is made of smooth muscle involuntary control
- external sphincter is made of striated muscle voluntary control
Urethra
coveys urine caudally from bladder
female - shorter tube, opening known as the external urethral orifice
Urethra
male: divided into the pelvic urethra and the penile urethra
normal micturition
clinical parameter
- daily volume
- appearance
-pH
-Specific gravity
normal range
- dog 20-100ml/kg
-cat 10-12ml/kg
-clear yellow
-5/7
-dog 1.016 - 1.060
-cat 1.020 - 1.040
polyuria
excessive urine production
anuria
there is no urine production
oliguria
low urine output
dysuria
difficulty passing urine
haematuria
blood in the urine
