Overview and comparative Flashcards
What are the main components of the urinary system?
- Kidneys
- Ureters
- Bladder
- Urethra
List the main functions of the kidney
- Endocrine function
- Acid base balance
- Water balance
- Detoxification
- Blood pressure
- Vitamin D and calcium
Blood glucose regulation
Briefly outline the endocrine role of the kidney
- Produces erythropoietin
- Activates vit D
Produces renin
Briefly outline the role of the kidney in acid-base balance
- Excretes excess electrolytes
- Moves ions around
- Greatest control of pH after the lungs
Briefly outline the role of the kidney in water balance
- Main role of kidney
- Control via sodium and potassium homeostasis
- Effect on blood volume and thus pressure
- Daily fluid intake can vary greatly, need to maintain constant state
- Mainly control of pressure rather than amount of water
Briefly outline the role of the kidney in detoxification
- Removal or organic waste e.g. urea and creatinine
- Water soluble only, liver deals with fat soluble
- Potassium
- Very effective
- Drugs bound to proteins will not be cleared
- Liver makes things water soluble so kidney can excrete them
Briefly outline the role of the kidney in blood pressure
- Produces renin, RAAS system
- Closed circulatory system - increase water = increased pressure
Briefly outline the role of the kidney in vitamin D and calcium
- Produces calcitriol (active vit D)
- Helps regulate calcium
Poor function can lead to demineralisation of bone and fractures, or mineral deposits in soft tissues
Briefly outline the role in blood glucose regulation
Site of gluconeogenesis
How do perineal hernias occur?
When muscles of pelvic diaphragm fail to support the rectal wall, most often in intact male dogs
What is the function of the obturator nerve?
Adduction of hindlimb
What is the function of the femoral nerve (L4-6)?
Motor to quadriceps and femoris muscle
What is the function of the pelvic splanchnic nerve?
- Parasympathetic GVE to pelvic viscera
- GVA from pelvic viscera
What is the function of the caudal cutaneous femoral nerve?
Sensory to skin of caudal thigh
What are the 3 tissue regions of the kidney?
- Inner pelvic region
- Medulla
- Cortex
Describe the generalised position of the kidneys
- Paired organs
- Retroperitoneal
- Dorsal abdomen
- Ventral lumbar region with limited mobility (except cat)
- Right kidney more cranial (except pig)
- Left kidney most mobile
Where does the right kidney lie in the pig?
- Does not touch the liver, unlike other species
- Last rib to 4th lumbar vertebrae
- Kidneys in line
Where are glomeruli found?
In the renal pyramids
What is the function of the glomeruli?
Production of urine
Describe the internal struture of the kidney
- Ureter divides, then divides at again
- At ends of branches have calices
- Calives situated next to/below renal pyramids
Why does the lobular structure differ between species?
- All species go through multi-lobular stage in development
- Varyiing degrees of fusion of these in different species
Which species have a pseudounilobular structure?
Dog, cat, sheep, horse
Which species have a multi-lobed structure with a smooth kidney surface?
Pig and human
Which species have a multi-lobed structure with a lobulated kidney surface?
Only cow
Which species have unilobular kidneys?
Rodents and lagomorphs
Where is the renal pelvis located?
Within the renal sinus at the hilus
Describe the renal pelvis of single lobe species
- Large irregular structure
- Broad finger-like processes called recesses (instead of calyces)
- Only 2 recesses in the horse
Describe the renal pelvis of multilobed, smooth surfaced kidneys
- Small irregular structure
- Short stems ending in calyces
Describe the renal pelvis of multilobed, lobular surfaced kidneys
Divided proximal ureter leading to multiple calyces
Describe the structure of the cat, dog, sheep and horse kidneys
- Lobes seen internally
- Pyramids partially merged
- Papillae merged to form renal crest
- No calices
- Singele pelvis
- Smooth surface
Describe the structure of the pig kidney
- Flattened, elongated
- Obvious pyramids
- Multiple renal papillae
- Multiple calices
- Branched pelvis
- Smooth surface
Describe the external appearance of the equine kidney
- More triangular
- Right heart shaped, left L shaped/pyramidal
- Cranial and caudal pole bent towards each other in middle at hilus
- Smooth outer
Describe the external appearance of the bovine kidney
- More oval, irregular
- Divided into separate zones
- External appearance not smooth (lobulated)
Describe the internal structure of the bovine kidney
- Same as dolphin and elephant
- Multipyramidal
- Multiple lobes
- Multiple renal papillae
- Multiple calices
- No pelvis
- Each stem of the ureter drains a lobe (which consists of one pyramid)
What is meant by a renal lobe?
A section of the kidney linked to one pyramid and papilla
What are the 2 regions of the cortex?
- External (outer zone)
- Internal (inner) juxtamedullary zone
Describe the internal structure of the canine kidney
- Medulla consists of medullary pyramids, outer part is base and inner part is single renal papilla
- Small zones of tissue dividing kidney into regions
- Instead of stems and calices have broad but irregular dilated area = renal pelvis
Describe the internal kidney structure found in rodents and lagomorphs
- Unilobular
- Single renal lobe
- Single pyramid
- Single papilla
- Still have cortex and medulla, less prominent pelvic region
What is an adaptation of the papilla found in desert adapted species?
The papilla may extend through the hilus
What are the anatomical landmarks of the left kidney?
- Cranial pole in contact with greater curvature of kidney
- Dorsomedial aspect of cranial pole contacts spleen laterally
- Cranially left kidney may contact the left limb of the pancreas
- Medially cranial pole contacts left adrenal gland
- Caudally small intestine and descending colon
- Ovary caudally and ventrally to kidney
What is the benefit of the location of the spleen in relation to the kidney?
Often ventral to kidney making useful acoustic window
What are the anatomical landmarks fo the right kidney?
- Cranial pole within renal fossa of caudate lobe of liver
- Medially: caudal vena cava
- Medial aspect: right adrenal gland (dorsolateral to the CVC)
- Ventrally: descending duodenum
- Ventrally and medially: right pancreatic limb
- Ovary: caudoventral to right kidney
Describe the route taken by the ureters
- From kidney to bladder
- One per kidney
- Parallel to spine
- Pass within retroperitoneal space
- Directed medially
- End on dorsolateral bladder surface (at neck)
- Within lateral ligament of the bladder
Compare the route of the ureters in males and females
- In females through broad ligament
- In males through the mesoductus
Describe the structure of the uretal wall
- Mucuous membrane, transitiional epithelium
- Lamina propria
- Muscular layer
- Adventitia
What is the main adaptation of the ureter?
- Stretch to allow pulses of urine to pass
- The transitional epithelium offers apical cellular protection against urine and wide range of adaptation if the wall is stretched
Describe the way in which the ureters connect to the bladder
- Enter obliquely at the neck
- Run intramurally between muscular layer and mucosa
- Then open through 2 slits often on slightly raised hillock
What is the function of the oblique entrance of the ureters into the bladder?
- Provides form of closure
- As pressure in the bladder increases, ureters are closed preventing urine being forced back up the ureters
What is it known as when the ureters do not open in the correct position?
- Ectopic ureter
- E.g. may empty directly into the urethra
Describe the structure of the bladder
- Hollow, muscular-membranous organ
Divided into cranial pole, intermediate body and caudal neck - Varies in size and position depending on degree of filling
Compare the appearance of bladder when empty vs full
- Wrinkled when empty
- Folds disappear when distended
- Wall thinner when distended
Describe the ureteric folds
- Extend from ureteral openings to neck of bladder where they fuse
- Region where ureteric folds join = urethral crest
- Continues into urethra
List the ligaments of the bladder
- 2 lateral ligaments
- Median ligament
Describe the lateral ligaments of the bladder
- Insert in dorsal abdominal wall
- Contain the residual umbilical vessels
Describe the median ligament of the bladder
- Connects bladder to pelvic floor and linea alba
Describe the female urethra
- Empties at extenral urethral orifice onto ventral wall of the vagina at tvestibulo-vaginal junction
- Length and diameter vary considerably between species
Describe the urethra in the mare
- Short and wide
Describe the urethra in the bitch
- Bordered by 2 fossae
Describe the urethra in the sow and cow
- Significant sub-urethral diverticulum
Desribe the general features of the male urethra
- Empties at tip of penis
- Divided into penile and pelvic portion
- Pelvic portion subdivided into pre-prostatic and prostatic
Where is pre-prostatic portion of the urethra in males?
From bladder neck to seminal hillock
Where is the prostatic portion of the urethra in males?
Includes opening of deferent, vesicular and prostatic ducts
Where is the penile portion of the urethra in males?
From the ischial arch to the penile tip
Which species have a simple urethra (male)?
- Canidae
- Porcidae
Which species have an Os Penis?
- Canidae
- Felidae
Describe the urethra in male cats
- Sigmoidal
- Small os penis
- Glans penis has many small barbs (regress when neutered)
Describe the urethral in male Equidae
Urethra inside the urethral fossa of the glans
Describe the urethra in male Bovidae
Urethra sits at the end of spiral groove in the glans
Describe the urethra in male Ovidae and Capridae
Urethra extends 3-4cm beyond glans of the penis
What are the main arteries supplying the urinary system?
- Renal
- Internal iliac
- External iliac
What arteries split off from the internal iliac?
- Umbilical (cranial vesicular)
- Urogenital
What arteries does the urogenital artery split into?
- Artery of ductus deferens
- Caudal vesicular artery
- Prostatic/vaginal artery
- Urethral artery
What arteries stem from the external iliac artery
- Caudal abdominal
- Deep femoral (middle vesicular)
Where do the renal arteries originate from?
Lateral aspect of the aorta
Describe the left renal blood vessels
- Left renal artery (3cm length) originates 2cm caudal to the right renal artery
- Left renal vein immediately ventral to the artery (3-4cm length)
Describe the right renal blood vessels
- Right renal artery arises 4 cm caudal to cranial mesenteric artery
- Transverses dorsal to caudal vena cava
- Vein immediately ventral to renal artery (4-5cm length)
Describe the order of renal blood flow, starting at the aorta
Aorta -> renal artery -> inter-lobar artery -> arcuate artery -> inter-lobular artery -> afferent glomerular artery -> glomerulus -> efferent glomerular artery -> renal tubule plexus -> inter-lobular vein -> arcuate vein -> inter-lobar vein -> renal vein -> caudal vena cava
Describe the arterial portal system within the kidney
- Efferent glomerular arterioles receive blood from capillaries of renal glomeruli
- Carry to peritubular capillary plexus surrounding proximal and distal convoluted tubules
Describe the renal portal system
Blood from caudal body enters kidneys = renal portal system
Explain the importance of the renal portal system
- Injections into tail/hindlegs may give lower plasma concentrations than expected
- May be nephrotocis due to higher concentration reaching kidney
- But effects not thought to be significant
What is unusual about the venous return from the caudal body in reptiles and crocodilians?
Can go via an extra set of veins to the liver
Describe the renal portal valve
- Directs blood flow
- Either to or past the kidneys
- Close to force blood into the kidney, rather than caudal vena cava
In what species is the renal portal valve found?
Birds
What is the importance of the renal portal valve?
- Injection into tail or leg veins can be passed through kidney
- Can be excreted rather than distributed, or may be reno-toxic
Describe the blood supply to the ureters
- Renal artery to renal pelvis and proximal ureter
- Cranial vesicular artery and vaginal/prostatic artery to distal ureter
What artery supplies the bladder?
Caudal vesicular artery
What artery supplies the urethra?
Urethral artery
Describe the innervation of the kidney
- Symp and para fibres from solar plexus via renal arteries
- Symp from synpase in coeliac ganglion and cranial mesenteric ganglion
Describe the innervation of the bladder
- Symp vai hypogastric from caudal mesenteric ganglion
- Para from pudendal nerve
What is the lymhatic drainage of the kidney?
Renal lymph nodes
What is the lymphatic drainage of the ureters?
Lumbar lymph nodes
What is the lymphatic drainage of the bladder?
Iliosacral lymph nodes
What organs make up the upper urinary tract?
Kidneys and ureters
What organs make up the lower urinary tract?
Bladder and urethra
Describe canine kidneys
- Bean shaped
- 2.5-3.5x length of L2 (VD view)
- Right kidney approx T13-L1/2, cranially in contact with caudate lobe of liver
- Left usually slightly futher caudal and ventral, separation of kidneys more obvious on RLR view
Describe feline kidneys
- More oval in shape
- More frequently superimposed
- More caudally positioned
- Cranial pole of right kidney more often separated from liver by fat (easier to see)
- Approx 2-3x L2 in length
Compare the appearance of the bladder in the cat and dog
- Dog more pear shaped
- Cat more ovoid
Describe the appearance of the bladder on radiography
- Soft tissue opacity
- Usually midline in VD view, easily displaced
- Normal urethra not visible on plain radiographs
