The urinary tract Flashcards
Label the kidney
On image
What are the main components of the urinary tract?
What are the main components of the urinary tract?
Kidney
The ureters
Bladder
Urethra
What are the approximate dimensions of the kidney?
125-170 grams.
12 cm in length and 6cm in width.
What is the position of the kidneys with respect to abdominal cavity, thoracic cavity and vertebral column. Why are they not at exactly the same level?
The kidneys lie retroperitoneally (behind the peritoneum) in the abdomen, either side of the vertebral column.
They typically extend from T12 to L3, although the right kidney is often situated slightly lower due to the presence of the liver. Each kidney is approximately three vertebrae in length, T12-L3.
What are the features of the kidney?
The renal parenchyma (solid part of kidney) consists of two areas which are the outer cortex and inner medulla. The cortex extends into the medulla, dividing it into triangular shapes which are known as the renal pyramids.
The renal pyramids themselves also have two regions. One being the apex of the pyramid called the renal papilla and each of these renal papillae are associated with a structure called the minor calyx which collects urine from these pyramids.
Several minor calices form a major calyx. Urine will pass through the major calices into the renal pelvis which is a funnel-shaped structure. It is from the renal pelvis that the urine drains into the ureter which then transports urine to the bladder.
What is the ‘hilum’ of the kidney and which structures are involved?
The renal hilum is the recessed central fissure where its vessels, nerves and ureter pass.
What is the arrangement of these structures from anterior to posterior?
Renal artery -> Renal vein -> Renal pelvis.
What is the blood supply to the kidneys and what volume per minute?
The blood supply to the kidneys is via the renal arteries and its is usually 1.1L per minute (in a 70kg male) for both kidneys together.
What is the function of the ‘ureters’? How long are they?
The ureters are two thick tubes which act to transport urine from the kidney to the bladder. They are approximately 25cm long and are situated bilaterally, with each ureter draining one kidney.
The ureters are retro-peritoneal and receive a blood supply from a variety of vessels along their route.
How do the ureters enter the bladder?
The ureters enter the lateral aspect of the bladder wall in an oblique manner (i.e diagonally) and this prevents the backflow of urine.
What is ureteric reflux?
Vesicoureteral reflux (VUR) is a condition in which urine flows backward from the bladder to one or both ureters and sometimes to the kidneys. VUR is most common in infants and young children. Associated with UTIs
What is the function of the bladder?
The bladder is an organ of the urinary system. It plays two main roles:
Temporary storage of urine – the bladder is a hollow organ with distensible walls. It has a folded internal lining (known as rugae), which allows it to accommodate up to 300-400ml of urine in healthy adults.
Assists in the expulsion of urine – the musculature of the bladder contracts during micturition, with concomitant relaxation of the sphincters.
It is a 3-sided pyramid with the apex pointing to pubic symphysis.
Identify its base, superior surface and 2 infero-lateral surfaces.
What is meant by the bladder ‘trigone’ and which structures enter/leave it?
he trigone (a.k.a. vesical trigone) is a smooth triangular region of the internal urinary bladder formed by 3 openings in the floor of the urinary bladder: the two ureteric orifices and the internal urethral orifice. The area is very sensitive to expansion and once stretched to a certain degree, the urinary bladder signals the brain of its need to empty.
Note the ‘trabeculated’ appearance of the ‘detrusor’ muscle, contraction of which results in emptying of the bladder.
What is the difference in length between the urethra in each sex and what is tthe significance?
The female urethra is ~4cm in length, it is fused with the anterior wall of the vagina. It ends between the clitoris and the vagina. The male urethra is ~20cm in length. Females are more prone to UTIs due to a shorter length.
What are the 3 parts of the male urethra and what is the length of each part?
Prostatic = 3-4 cm.
Membranous = 14-16 cm.
Penile/Spongy = 2 cm.
The prostatic urethra begins at the bladder neck and lies within the prostate. It is usually 3 cm long. It is the widest and most readily dilated portion of the urethra. It typically emerges anterior to the prostatic apex and merges with the membranous urethra. The membranous urethra lies within the urogenital diaphragm surrounded by the sphincter urethrae muscle and is the least dilatable portion of the urethra. The prostatic and membranous urethra are lined with transitional epithelium. The spongy (cavernous) urethra is enclosed in the corpus spongiosum.
