Urinary Tract Structure and Function 1

Question 1

Renal?

Answer 1

Pertains to the kidneys.

Question 2

Renal sinus?

Answer 2

A recess in the substance of the kidney, occupied by the renal pelvis, calices, vessels, nerves, and fat.

Question 3

Renal pelvis?

Answer 3

The funnel shaped expansion of the proxmial end of the ureter, it is usually within the renal sinus.

Question 4

Renal papilla?

Answer 4

The blunted apex of a renal pyramid.

Question 5

Calix?

Answer 5

A cuplike organ or cavity, for the kidney, one of the recesses of the kidney pelvis which enclose the tips of the pyramids.

Question 6

Renal lobe?

Answer 6

Comprising the tissue contributing to each pyramid.

Question 7

Urinary system?

Answer 7

The main organs of the urinary system:
1.) Pair of kidneys: filter the blood.
2.) Pair of ureters: drains urine from kidney.
3.) Urinary bladder.
4.) Urethra.

Question 8

Upper and Lower urinary tract?

Answer 8

-Upper:
1.) Kidneys.
2.) Ureters.
-Lower:
1.) Urinary bladder.
2.) Urethra.

Question 9

Overview of urinary tract?

Answer 9

-The kidneys are paired.
-The kidneys form urine from blood.
-The ureters convey the urine from the kidneys to the urinary bladder.
-The urinary bladder stores the urine.
-The urethra is the passage from the bladder that the urine passes through to reach the exterior: in addition, the urethra in the male conveys the reproductive products.

Question 10

Kidneys- function?

Answer 10

-To gain an appreciation of the anatomy of the kidneys, it is helpful to think of this in combination with their main function.
-One of the main functions of the kidneys is to maintain the internal environment: link to homeostasis lecture.
-The kidneys maintain the internal environment by filtering the plasma.

Question 11

Plasma composition?

Answer 11

Plasma is made up of:
1.) Water.
2.) Proteins: primarily albumin, globulin, and fibrinogen.
3.) Electrolytes: such as sodium, chloride, and hydrogen carbonate.
4.) Dissolved gases.
5.) Nutrients: such as glucose, lipids, amino acids, vitamins.
6.) Waste products: such as urea, creatinine, uric acid, and lactic acid.
7.) Hormones.
-Initially when filtering the plasma they extract a huge amount of fluid and then subject this ultafiltrate to further processing, such as:
1.) Selectively reabsorbing useful substances.
2.) Concentrating waste products for elimination/removal in the urine.
3.) Altering water concentration to maintain the composition of plasma within the appropriate range.

Question 12

What are the two endocrine functions of the kidneys?

Question 13

What glands are situated near the kidneys?

Answer 13

Adrenal.

Question 14

Kidney- gross anatomy?

Answer 14

-The kidneys are a firm, reddish-brown gland.
-The external appearance of the kidneys varies among mammals:
1.) Kidney shape: dogs, cats, small ruminants.
2.) Flat-shape: pigs.
3.) Heart-shaped: horses.
4.) Lobulated-shape: bovine.
-The kidneys are usually found against the abdominal roof (i.e., dorsally) at the lumbar region.
-Genereally, the right kidney sits further cranially than the left: expect for pigs.
-The right kidney, sitting more cranially, within the renal impression (fossa) of the caudate liver lobe.
-The right kidney is a bit more firmly fixed because of liver fossa, while the left is more mobile and sags within the abdomen.
-The kidneys are each covered by a fibrous capsule that should peel off easily (except at the hilus).
-The ventral surface of the:
1.) Right kidney: descending duodenum, pancreas, caecum, and ascending colon.
2.) Left kidney: descending colon, jejunum (spleen is related to cranial pole).
-The kidneys are retroperitoneal and surrounded (or almost entirely covered) by fat.
-The kidneys have a nice smooth outer surface which is convex: the bovine kidneys have a smooth, but lobulated texture.
-On the medial aspect of the kidneys there is an indentation.
-The indentation leads to a space, the renal sinus, which is occupied by the start of the ureter, the renal pelvis.
-Vessels, nerves, and fat are also located at the indentation.
-The indentation is referred to as the hilus.

Question 15

Kidneys on cross-section?

Answer 15

-The parenchyma of the kidneys are enclosed by a tough fibrous capsule (as discussed eariler).
-When a kidney is cut in a cross-section you can clearly see the parenchyma is divided into:
1.) Outer cortex.
2.) Inner medulla.

Question 16

Kidney- medulla?

Answer 16

-In many species, the inner medulla is arranged as several discrete masses each roughly a pyramid shape.
-The base of the pyramid is capped by the cortex.
-The apex of the pyramid points towards the renal sinus and forms a papilla.
-The papilla fits into a cuplike expansion (called a calix) of the renal pelvis.
-Each of these medullary pyramids with its associated outer cortex forms a renal lobe.
-Kidneys with this organisation are called multipyramidal or multilobar: the external lobes of the bovine kidneys mark the boundaries between the internal pyramidal lobes.
-All mammalian kidneys pass thorugh a multipyramidal phase in thier embryological development.

Question 17

Kidneys- pyramids?

Answer 17

Renal lobes are fused to varying degrees depending on species.

Question 18

Kidney- blood supply?

Answer 18

-Each kidney is supplied by a renal artery, a direct branch from the abdomnial aorta.
-The renal artery then divides into several interlobar arteries: these follow the division between the renal pyramids (still present or use to be present).
-The interlobar arteries give rise to arcuate arteries: these arteries curve over the base of the pyramids.
-The interlobar arteries give rise to the interlobular arteries and are located in the cortex: these give rise to the afferent arteriole supplying the renal glomerulus.

Question 19

The nephron?

Answer 19

-The nephron is the functional unit within the kidney.
-Simplistically and in layman’s terms, it is a really long epithelial tube divided into different sections with varying convolutions (twists and turns).
-Each interlobular arrtery gives rise to a cluster of capillaries called the glomerulus.
-The nephron begins as a blind ended cup-shape expansion, invaginating the glomerulus.
-The glomerulus and the cup-like expansion of the nephron are collectively called a renal corpuscle.
-The renal corpuscles are scattered across the cortex giving the cortex a fine granular appearance.
-The long epithelial nephron tubule is then sequentially divided into the following sections:
1.) Proxmial convoluted tubule.
2.) Descending and ascending limb of nephron.
3.) Distal convoluted tubule.
4.) Collecting tubules and ducts.

Question 20

The nephron- Proximal convoluted tubule?

Answer 20

Proximal convoluted tubule.
-Longest and most convoluted part of the nephron, comprising much of the renal cortex.
- A rich capillary network surrounds the proximal convoluted tubule and returns absorbed molecules to the circulation.
-Lined by a simple cuboidal epithelium with a prominent brush border.

Question 21

The nephron- Descending and ascending limb of the nephron/loop of Henle?

Answer 21

Loop of Henle:
-Starts at the cortex and extends into the medulla.
-The thick descending/ascending limbs are lined by cuboidal epithelium.
- The thin descending/ascending limbs are lined by simple squamous epithelium.

Question 22

The nephron- distal convoluted tubule?

Answer 22

Distal convoluted tubule:
-Shorter tubule.
-Lacks a brush border compared to the proximal convoluted tubule.
-Has a larger lumen on transverse cross-section.

Question 23

The nephron- Collecting duct?

Answer 23

Collecting duct:
-Each collecting tubule serves many nephrons.
-Opens into a large papillary duct close to the apex (i.e., tip of the pyramid).

Question 24

Ureters?

Answer 24

The proximal end of the ureter is either:
-Expanded to form the renal pelvis (most domestic species; carnivores, horses, sheep).
-The papillae drain into calyces, which drain into two branches of the ureter (bovine).
-The papillae drain into calyces, which drain into a renal pelvis (Pig).
-The inner mucosal lining forms longitudinal folds, allowing for expansion.
-Consists of two muscular coats:
1.) Outer circular.
2.) Inner longitudinal.
-Peristaltic waves of contraction move the urine to the bladder.
-Penetrate the dorsal surface of the urinary bladder wall at an oblique angle.

Question 25

Urinary Bladder?

Answer 25

-The urinary bladder is very distensible and, because of this, doesn't have a constant size, portion, or relationship to other organs. -The urinary bladder consists of: 1.) Apex. 2.) Body. 3.) Neck. -The urinary bladder is supported by three ligaments: 1.) Median ligament x1: runs from the apex to the umbilicus (in the foetus, supports the urachus). 2.) Lateral ligaments x2: run from the bladder to the pelvic wall (contain the round ligaments, which are remnants of the umbilical arteries). -When empty, the mucosa of the urinary bladder is corrugated and has a negligible lumen. -When the urinary bladder extends with the filling of urine, it becomes pear-shaped with an obvious apex, body, and neck. -As the urinary bladder distends with urine, it extends into the abdomen, but the neck remains fixed in the pelvis due to its continuation with the urethra.

Question 26

Ureters and Bladder?

Answer 26

-The ureters enter the bladder on the dorsal surface at an angle. -The angle prevents urine flowing back up the ureter.

Question 27

Urinary bladder muscles?

Answer 27

-The bladder muscle is made up of three sheets of muscle. -The arrangement of the three sheets is often described as detrusor (detrusor= a general term for a muscle that expresses a substance). -The external sphincter is formed by the striated urethras m.

Question 28

Urinary bladder- innervation?

Answer 28

-Autonomic fibres reach the urinary bladder via: 1.) Sympathetic from hypogastric nerves: urine storage (e.g., continence). 2.) Parasympathetic from pelvic nerves: urine evacuation (e.g., micturition). -Sensory fibres are reached via the pudendal nerve. -Blood supply to the urinary bladder via vaginal (or prostatic) artery and supplemented by reduced umbilical arteries: vaginal (or prostatic) a branch of the internal iliac a.