Urinary System Flashcards
List the components of the urinary tract
Kidneys
Ureters
Bladder
Urethra
What is the function of the urinary system?
Process plasma to excrete waste and maintain homeostasis of electrolytes, pH and blood volume
What shaped kindeys do humans, dogs, cats, sheep, goats and rabbit have?
Kidney bean shaped
Why are human kidneys covered in perirenal fat?
Protection from pressure, shock, trauma
How much perirenal fat do dog and cat kidneys have?
Very little
Which species has very little perirenal fat and visible veins running from the hilum?
Cat
Which species has large amounts of perirenal fat?
Sheep
What shaped kidneys do pigs have?
Dorsoventrally flattened/flat kidney bean
Describe the shape and position of cows kidneys
Lobed kidneys marked by fissures and connective tissue.
Twisted left kidney from development, pushed towards midline by rumen
What shapes are horses kidneys?
Left- kidney bean shaped
Right- love heart shaped
In horses which kidney is more cranial?
Right
Where are human kidneys positioned in the abdomen?
Posterior wall of superior abdomen between T12 and L2
Which kidney is slightly higher in humans?
Left
How are kidneys positioned in relation to the peritoneum?
Retroperitoneal
What are the relations of human kidneys?
Anterior- stomach, liver, start of small intestine
Superior- adrenal glands
Inferior- quadratus lumborum and psoas major muscles
Posterior- ribs and perineal fat
Where are domestic species kidneys typically positioned in relation to the vertebrae?
Left- L3-L4
Right- L1-L2
Which species has kidneys on the same level?
Pigs
Why is the left kidney of cats easier to palpate?
Less retroperitoneal so more mobile and easier to palpate
What is the functional unit of the kidney?
Nephron
What is the glomerulus and what does it do?
Tight capillary network to form filtrate from the blood
Where is the bowman’s capsule found?
Surrounding the glomerulus
Describe the role of the bowman’s capsule
Collect filtrate, produce ultrafiltrate and pass alone to proximal convoluted tubule
Where does the ultrafiltrate drain after being formed?
Proximal convoluted tubule
Loop of henle
Distal convoluted tubule
Collecting ducts
What are renal lobes made of?
Medullary pyramid in individual cortex
What is within the hilus?
Renal vein
Renal artery
Renal nerve
Ureter
Why do the renal arteries arise from the aorta?
Allows filtering of huge amounts of blood
Where do the renal veins drain to?
Inferior vena cava
Why can’t human kidneys expand?
Surrounded by tough fibrous capsule
What is in the renal corpuscles and where are they found?
Glomerulus, Bowman’s capsule and convoluted tubules
What is in the kidneys medulla?
Loops of henle and collecting ducts
Renal pyramids and renal papillae
What is the role of renal papillae?
Where collecting ducts drain into papillary ducts
What are calyces?
Collect urine from renal papillae and drain into ureters
What is the renal sinus?
Space in centre of kidneys containing renal pelvis, fat and blood vessels
What is the renal pelvis?
Extensions of ureters into kidney
Name the type of kidneys found in different species.
Multipyramidal/multilobar
Multipapillate
Unipyramidal/unilobar
What type of kidney is in dolphins and ox? Explain this type of kidney.
Multipyramidal/multilobar.
Cortex and medulla is divided by connective tissue. No renal pelvis as drain into individual calyces directly into ureter
What type of kidney do humans and pigs have? Explain this type of kidney
Multipapilate.
Separated medulla and calyces but fused cortex and single pelvis
What species have a unipyramidal/unilobar kidney? Explain this type of kidney.
Dogs, horses, sheep.
Fused cortex, medulla and one renal pelvis for papilla to empty into
Why do some animals have longer loops of henle?
It allows water conservation as they can concentrate urine more easily
What are ureters walls made of (muscle and epithelium type)?
Smooth muscle and urothelium/transitional epithelium
Why does urine need to be move down the ureter by peristalsis?
Bladder is at higher pressure than the kidneys
What arteries does the blood supply for ureters come from?
Renal, gonadal, common iliac and internal iliac
How does the entry of dogs ureters differ from humans?
Enter at oblique angle due to being partially in broad ligament, closely associated with uterine horns
How does the horseshoe kidney abnormality come about? Does this have any effect on function?
kidneys fuse in inferior pole.
Normal function but prone to stones
What is unilateral renal hypoplasis?
One kidney over developed and one kidney underdeveloped, possibly non-functioning
What condition is due to 2 renal pelvises per kidney?
Bifid renal pelvis
What is bifid ureters?
2 ureters per kidney
What are the stages of kidney development in the embryo?
Pronephros- develop near neck with pronephric duct
Mesonephros- develops in middle of embryo, has mesonephric duct
Metanephros- final kindey, develops from mesonephric duct
What is the ureteric bud in developing embryo and where does it originate?
Originates from mesonephric duct to become ureter, calyces, collecting duct and collecting tubule
What is the purpose of salt glands in marine vertebrates and birds?
Supplement kidney function to remove excess salt to prevent dehydration
What are the relations of the bladder in humans?
Anterior- pubic symphysis
Superior- uterus/intestines and peritoneum
Inferior and lateral- pelvic floor/prostate gland
Posterior- vagina/seminal vesicles, ductus deferens and rectum
What is a vestible?
Common structure in domestic females where urethra joins the vagina
What type of muscle walls does the bladder have to allow voiding of urine under autonomic control?
Smooth detrusor muscle
What is the bladder lining made of?
Mucosa folded into rugae and lined with urothelium
What prevents urine traveling back to kidneys from bladder?
Ureters enter at oblique angle to act as spincter
What nerve supplies the external urethral sphincter? What is its function when the nerve is active on the sphincter?
Pudendal nerve contracts the sphincter when its active
What is the arterial blood supply to the bladder?
Internal iliac branching into superior and inferior caudal vesical arteries
Where does blood from the bladder drain to?
Internal iliac vein
Where is the trigone points found?
Urinary orifices and internal urethral meatus
What is the function of the trigone?
Prevent over expansion as can’t distend as much as the rest of the bladder
What germ layer does the urinary tract derive from?
Endoderm
When does the cloaca develop into 3 separate tracts in the embryo?
5-6 weeks
What is the allantosis?
Part of developing urinary tract going through umbilical cord to the placenta, develops into urachus
Where does the urogenital systems develop from?
Urogenital sinus
When does the gut tube and and urogenital systems separate in the embryo?
7-8 weeks
What is the patent urachus abnormality?
Urachus doesn’t close so urine also exists via umbilicus
What is urachal diverticuli?
Urachus half closes forming a pouch holding urine
What are the 3 sections of the male urethra?
Prostatic
Membranous
Penile
Is the bladder under autonomic or somatic control?
Autonomic
How is retrograde ejaculation prevented?
Internal urethral sphincter
What lines the urethras smooth muscle?
Urothelium transitioning to stratified squamous
What is the positioning of the cats urethra?
Backwards with right angle turn
What is the difference in positioning of female and male dogs urethra?
Males- abdominally placed, mainly straight line
Females- caudally along pelvic floor opening ventrally into vestibule
Where is the sensory bladder innervation and what are the nerves?
General visceral afferents mostly in trigone
What is the parasympathetic innervation of the bladder?
Pelvic splanchnic nerves contract detrusor muscle
What innervates the internal urethral sphincter to relax and contract?
Relax- pelvic splanchnic nerve
Contract- hypogastric nerve
What is the sympathetic innervation of the bladder?
Hypogastric nerve relaxes detrusor muscle
What causes micturition?
Visceral afferents go to sacral spine in pelvic splanchnic nerves then to brain
What are the causes of incontinence?
Overflow- urethral blockage, pressure pushes some urine out
Stress- relaxed pelvic floor so abdominal pressure causes leakage
Urge- oversensitive bladder when little urine present to void
