Lecture 62 - Kidney and urinary system Flashcards
What is the role of the kidneys?
Produce urine.
What solid viscera do kidneys contact? What aspect?
Supramedial aspect contacts the adrenal glands.
What are the dimensions of a healthy kidney in a normal person?
10cm long; 5cm wide; 2.5cm thick
Are the kidneys intra- or retroperitoneal?
Retroperitoneal
What does the anterior surface of the kidneys contact? What does the posterior surface of the kidneys contact?
Anterior surface: peritoneum
Posterior surface: posterior abdominal wall
Describe the location of the kidneys relative to the posterior abdominal wall.
Below the diaphragm either side of the lumbar vertebral column, T12-L3, with the top of the kidneys sits anterior to the 12th rib.
Are the kidneys fixed in place? Why or why not?
No; they move with the diaphragm, ie during respiration.
Why is the left kidney slightly higher than the right kidney?
Because of the liver.
Where do the kidneys sit relative to the vertebrae?
Almost behind the lumbar vertebrae in the ‘paravertebral gutter.’
From which aspect is it easier for a surgeon to operate on the kidneys?
Posteriomedially; don’t have to go through as much viscera and just have to remove the 12th rib.
What type of viscera are kidneys?
Solid
What are the two ways that solid viscera may be organized? Give examples, one of which are the kidneys.
Lobes and lobules (eg, liver); or cortex and medulla (eg, kidneys)
Kidneys are made of a cluster of what type of cell?
Secretory cells.
What three structures encapsulate the kidneys. (From outside to inside)
Perirenal fat (which can be very thick), serous membrane (anteriorly), and the fibrous capsule.
In which direction does the hilum of each kidney face? Why?
Anteriomedially because the kidneys sit in the perivertebral gutter and therefore the IVC and the abdominal aorta sit anteriorly to the kidney.
From anterior to posterior, what three large structures does the hilum of the kidney transmit?
Renal vein, renal artery, ureteric/renal pelvis.
What five structures pass through the renal hilum?
Renal vein, renal artery, ureteric/renal pelvis, nerves and lymphatic vessels (nerves and lymphatics are not organized anterior to posterior and are very small.)
What three words describe the cortex of the kidney?
Outer, pale, continuous.
What three words describe the medulla of the kidney?
Inner, discontinuous, darker
How is the medulla of the kidney organized?
Arranged into a series of triangular collections of medullary cells, called renal (or medullary) pyramids.
What is the relationship between the cortex and the medulla?
The cortex completely surrounds the medulla.
Describe the shape and orientation of the renal medulla.
Pyramidal; base facing exteriorly toward the cortex, apex facing interiorly toward the renal pelvis.
The ureteric pelvis connects with what fat-filled space within the kidney?
The renal sinus.
Which of the two renal arteries are shorter? Why?
The left is shorter because the left kidney sits directly beside the abdominal aorta.
What structure does the right renal artery have to traverse? Is it anterior or posterior to this structure?
The right renal artery passes posteriorly to the IVC because arteries never sit in front of veins.
Why do arteries usually pass behind veins?
Arteries, because the are muscular, have high pressure, and pulsate, may compromise or compress veins if they were in front of the vein.
Paired abdominal structure receive arteries from which aspect of the abdominal aorta?
The lateral aspects.
Normally, how many renal segmental arteries are there? Where do they go?
There are normally 5 renal segmental arteries that supply each of the 5 segments of the kidneys.
How come some people have 6 renal segmental arteries? (Ie, an accessory artery.)
During renal development the kidneys start lower and develop at a slower rate upwards than the post abdominal wall. So, they get their blood supply from the abdominal aorta at different levels during different stages of development. As they go up they get new arteries and the old ones obliterate, usually – occasionally you keep an artery.
What is a key feature of vital structure in the body? Why?
The are divided into functionally independent units so that if one unit has pathology than it does not affect the entire organ.
What is the surgical importance of discrete functional units of the kidney?
If one unit is damaged or cancerous than the surgeon may remove it without compromising the rest of the kidney’s function.
True or false: each of the 5 functional units of the kidney have a discrete arterial blood supply but they all share the same vein.
False: each segment has its own artery and vein and each of them produces its own portion of the urine from that kidney.
The renal vein drains directly to what structure?
The IVC
Which of the two renal veins is longer? Why?
The left because it has to traverse the aorta. Again, it transverses in front of the aorta.
How many segmental veins are there? Where do they drain to?
5: one for each segment. Each segment drains to the renal veins, which drains to the IVC.
What is the renal pelvis?
Flattened, dilated, funnel-shaped structure at the renal end of the ureter.
What is the ureteric pelvis made up of?
2-3 major calyces.
What is each major calyces made up of?
2-3 minor calyces
What do the apexes of each of the medullary pyramids drain into?
Each medullary pyramid drains into its own minor calyx.
Briefly describe the ureters.
The ureters are muscular tubes that transport urine from the kidneys to the bladder, classically said to be 25-30cm long.
What is the relationship between the ureters and the posterior abdominal wall and peritoneum?
Retroperitoneal and in direct contact with the posterior abdominal wall.
What are the four parts of the the ureters’ journey to the bladder?
- On the post ab wall
- Across the pelvis brim
- Along the side wall of the pelvis
- Approaching the bladder
Where are the three sites of compression of the ureters?
- Very beginning - “Pelvi-ureteric junction.”
- Very end as it obliquely traverses the muscular wall of the bladder.
- Kink where the ureters cross of the pelvic brim.
Describe the arterial blood supply to the ureters.
They receive their blood supply depending on what region they are traversing, ie there is no ‘ureteric artery.’
What is the clinical significance of the kink in the ureters?
Most likely locations at which kidney stones may become lodged.
The pelvic part of the urinary system consists of what three viscera?
Terminal ureters, bladder, and urethra.
What is the most anterior pelvic viscera in both males and females?
The bladder.
Is the bladder contained entirely in the pelvis?
TRICK QUESTION!!! Yes, when it is empty but as it fills with urine it expands into the inferior abdominal cavity.
Briefly describe the shape and orientation of the bladder.
Like a tipped forward pyramid with the apex pointing anteriorly and the base facing posteriorly.
Describe in interior surface of the bladder.
Mostly ridged muscle call detrusor muscle except for the trigone, which is smooth-surfaced muscle in the shape of a triangle with the apex pointing toward the neck of the bladder. The entire surface is covered in mucous.
Where are the ureteric entries and the neck of the bladder relative to the trigone?
Ureteric entries: suprolateral points of the triangle.
Neck of the bladder/urethral exit: the medio-inferior apex of the triangle
How is the bladder supported and stabilized?
Neck of the bladder is supported and stabilized by ligaments whilst still allowing the fundus of the bladder to expand.
How do the ureters enter the bladder? Why?
Obliquely; when the bladder contracts the oblique path of the ureters prevents back flow so the urine only passes into the urethra.
Is the male of female ureter longer?
Male
What are the good and bad consequences of a short urethra in females?
Good: easily catheterized
Bad: more urinary tract infections because it is only a short distance for microbes to travel to the bladder.
What are the good and bad consequences of a long urethra in males?
Bad: more difficult to catheterized
Good: less urinary tract infections because it is only a short distance for microbes to travel to the bladder.
Describe the passage of the male urethra.
4 (5ish) parts:
- At the neck – pre-prostatic part of the urethra
- Prostatic part of the urethra - Surrounding the first part of the male urethra is the prostate gland.
- Membranous part of the urethra – bit that traverses the perennial membrane
- Penile part of the urethra
- Urethral orifice
Describe the passage of the female urethra.
Urethra goes from the bladder, through the peroneum and out into the vulval vestibule (central part of the external genitalia) between the labia.
What is the clinical significance of the prostatic part of the male urethra?
Prostatic hypertrophy (eg, cancer or inflammation) is associated with urinary symptoms in elderly males because of the compression of the prostatic part of the urethra, from inflammation or cancer.
