Structure of the Urinary System

Question 1

Describe the capsule

Answer 1

Covering of the entire kidney that is dense irregular CT

Question 2

Explain the features of the cortex

What is a lobe

Answer 2

Outer region of kidney that has renal corpuscle and tubules (Convuluted, straight and CD). Has pyramids- that are conical regions that have convoluted tubules and their vessels and the pyramids are separated by renal columns. Renal colums have mainly collecting ducts and their accompanying vessels most notably the interlobular arteries.

Tissue from the mddle of one renal column to the middle of the next– it contains both the cortex and medulla

Question 3

Explain what a lobe is

What are its further divisions

Answer 3

Lobe is medulla and cortex from the middle of one renal column to the next

Medulla – region between cortex and calyces. Contains straight tubules, collecting ducts and vasa rectae.
Calyces and renal pelvis – Inner region formed of funnel like structures that convey urine from the medulla to the ureter.

Question 4

Explain epithelial of BC and other features.

Answer 4

A hollow spherical structure formed by simple squamous epithelium indented by the
glomerulus (a looping capillary between the afferent and efferent arterioles)

Visceral layer which invests the glomerulus is formed of specialized epithelial cells called podocytes. The podocytes and endothelial cells of the glomerulus form the filtration apparatus of the kidney.

Question 5

Explain what podocytes are and what they do to the glomerulus

Answer 5

Completely engulf the glomerulus through their epithelial cells with extensive branching cytoplasmic processes. Podcyte s have primary and secondary branches that form small pedicels with fine sitls. The slits have a protein complex link to the actin cytoskelton and together contirbute to regulation of protein passing through urine.

Question 6

What is the GBM an attachment site for? What type of collagen does it contain

Answer 6

GBM is the attachment site for the podocytes and for the endothlial cells and is the principal barrier to protein entering urine.

Has collagen Type 4 and 18 and laminin, firbonectin, entactin, proteglycans. The GAGs give it a strong negativ charge and block movement of proteins. CHanges in the GBM (like in diabetes) can dramtically chagne the fluids passing through.

Question 7

Epothelium throughout nephron

Answer 7

Proximal convoluted- simple cubodial

Loop of Henle- thick descneidng and ascending= stimple dubodial

Thin ascending and descending- stimple squamous that varies in type depending on nephron

Distal convoluted Tubule- simple cubodial

Collecting Ducts- simple cubodial

Question 8

Function of Mesangial cells

Answer 8

they are in BC and near the JG appartus and in BC they endocytose immune complexes and plasma proteins and ensure normal filtration. They increase in number and growth factors, interleukins, prostagladins and play a role in glomerular inflmmation in the disease state

Question 9

Characteristics of Procimal COnvulteud Tubule

Answer 9

SImple cubodial that have many microvilli and extensive foling of basal surface plasma membrane. Have Large motochondria which is important for the extensive ion movement.

Primary site of reabsorption of Na, Glucose, AA, Bicarb

Question 10

Characterisitcs of the Distal Convoluted Tubule

Answer 10

1. About 1/3 in length of the proximal
2. Has simply cubodial microvilli much reduced in size and number compared to the proximal

3, Mitochondria and basal folding are still numberous serving in functions of sodium, bicarb and ammonium transport

Question 11

Where are the nephrons with longest loops

Answer 11

Closest to the cortico-medullary border

Question 12

Characteristics of CD (epithelia, where are they, features)

Answer 12

1. SImple cubodial epithelium that becomes columnar as duct gets larger
2. Small mircobilli and PRIMARY CILLI
3. CD are clustered together in the cortex in regions medullary reays and then run down to the medulla. at the tip of the pyramids, the paillia, they are now called papilary ducts.
4. Epithlium is active in ion movement and concentration of pH of urine

Question 13

Explain the path of blood supply to kidneys— remember the location of each transiiton

Answer 13

Renal artery—> interlobar arteries (at the point of renal pelvis)—> Arcuate Arteries- these are side way branches (at the corticomedullary border)—> Small interlobar arteries project into the cortex —> afferetn arteriole—> glomerulus—> efferent arteriole

** Arcuate can go to small itnerlobar or straight to vas recta***

***Small interlobular can go to afferent or to stellate or peritubular arteries***

Effernt can do 2 things

1. Peritubular capillaries (cortical nephron)- a capallary bed through the cortex around convoluted tubules

2, Vas rectae (juxtamedullary nephonr)- from the glomerulus of nephron that is near the cortex/medulla border then it makes long loops parllell to the loop of Henle

Question 14

Explain the venous drainage

Answer 14

CApillarie beds to stellate veins to small interlobular veins to arcuate veins to interlobar veins

Question 15

Features of the Ureters

Answer 15

Urie collects throguh minor and major calyxes with a funnel like arragnemtn emptying into a single ureter

Ureter are musclular tubes line with transitional epithelium which is unique to the urinary system (pelvis, ureters, bladder)

Lamina propria, then 2-3 layers of smooth muscle then serosa

Question 16

Chacarteristics of BLadder- locatin, innervation, epithlium, serosa or adeventitia?

Answer 16

Highly distensible, muscular (thick and thin smooth muscle= detrusor muscle) organ that is storage for urine located posterior to the pubic symphsis

Outer that projects to the pelvic cavity is covered by serosa and other by CT adventitia

Parsym- activatd by stretch receptors that contract the detrusor muscles voiding the bladder—this is done in concert with CNS which may/may not override the contractio of the detrsuor by regulation of sphincter muscles

BLadder= transitioanl epitheliu- has stratified epithelim that appears to be cubodial in conctracted state.

With stretch bladder increases its surface area by unfolding extensive invaginations of plasma mebrane

Question 17

Characteristics of Urethra- explain male female differneces, position

Answer 17

We have a single urethra leaving the inferior portion of the bladder

Females- short tube terminating in the vestibule superior to the vagina—- usually to columnar or cuboidal to stratified squamous as it approaches the urethral orifice

Males= urethra is a duct for urine and reproductive system