32/33. Urinary System

Question 1

Functions of the urinary system

Answer 1

Storage and excretion of urine
Regulation of blood volume (directly regulator of blood pressure)
Regulation of ion levels (Ca+, Na+, K+)
Regulation of acid-base levels (H+)
Regulation of erythrocyte production (secretion of erythropoietin)

Question 2

Function of erythropoietin and relation to kidney disease:

Answer 2

In response to a drop in tissue oxygen pressure (hypoxia), erythropoietin is produced by cells in the renal cortex
Pts with chronic kidney disease cannot filter toxins and accumulation of toxins effects availability of erythropoietin and ability to produce new red blood cells
Result is lowered oxygen availability in organ tissue and subsequent organ failure

Question 3

Initial Embryonic development of urinary system

Answer 3

Urogenital system derives from embryonic tissue called intermediate mesoderm
As the intermediate mesoderm runs down the posterior abdominal wall of the developing embryo, it will begin to condense and form two bilateral ridges, Known as urogenital ridge
Pronephros develop from urogenital ridge and instigate mesonephros development

Question 4

Urogenital system development by week 4

Answer 4

Mesonephros act as a temporary set of excretory organs
They are composed of multiple saclike segments
The mesonephric duct drains each mesonephros to the developing bladder
Mesonephros persist till week 10

Question 5

What occurs at 5th week of urogenital system development

Answer 5

Metanephros develop and act as temporary set of excretory organs
They are fully functional by week 10 and take over as final excretory organ
They develop from ureteric buds and metanephric mesoderm

Question 6

Ureteric buds develop into

Answer 6

Structures that will collect urine
Ureter, renal calyces, renal pelvis, and collecting ducts

Question 7

Metanephric mesoderm develops into

Answer 7

Nephron components of kidney
Structures that will produce urine
Glomerular capsule, proximal convoluted tubule, nephron loop, distal convoluted tubule

Question 8

Characteristics of indifferent duct system

Answer 8

All embryos develop an indifferent duct system
Genetics will determine which duct system is retained
Retention of mesonephric duct will result in development of penis, etc
Retention of paramesonephric duct results in develop,ent of uterus, etc

Question 9

Organs of urinary system and their overall functions

Answer 9

Paired kidneys: filter waste from bloodstream and convert filtrate into urine
Ureters, urinary bladder, urethra: (urinary tract) transport the urine out of body

Question 10

Location of kidneys and what gland is also found nearby

Answer 10

Superior border sits just below T12 vertebrae
Inferior border sit at about L3
Kidney is retroperitoneal
Suprarenal or adrenal gland sits atop each kidney
Right kidney sits slightly more inferior than left kidney
Kidney sits on posterior aspect of abdomen so easily accessible in surfery

Question 11

How are kidneys supported?

Answer 11

Cushioned by two layers of fat

Question 12

Characteristics and functions of fibrous capsule of kidney

Answer 12

Dense, irregular connective tissue
Maintains shape of kidney
Protects kidney from damage
Prevents infection from spreading
Concave medial border: hilum

Question 13

Internal structure of kidney

Answer 13

Consists of cortex and medulla
Cortex is outer region that divides the medulla into pyramidal shaped regions called pyramids
Base of medulla forms the corticomedullary junction with the cortex
At the apex of the medulla is the papilla

Question 14

Drainage of urine in medulla

Answer 14

Urine formed in medulla drains from papilla into minor calyx
Urine collecting in multiple minor calyces will drain into one major calyx

Question 15

Components of the collecting system

Answer 15

Medulla produces urine
Papilla
Minor calyx
Major calyx
Renal pelvis
Ureter
Bladder

Question 16

Primary function of kidney

Answer 16

Blood filtration

Question 17

Blood supply to and from kidney

Answer 17

Blood carried to kidney by renal arteries which branch off the abdominal aorta
Renal veins bring deoxygenated blood back to IVC
Renal veins lie superior to arteries and are asymmetrical due to location of IVC
Left renal vein is longer than right and collects blood from left gonadal vein

Question 18

Order of blood supply to the kidney

Answer 18

Renal artery
Segmental arteries (5 branch off)
Interlobar arteries: between pyramids
Arcuate arteries: across tops of pyramids
Cortical arteries: penetrate cortex and give off afferent arterioles
Afferent arterioles are smallest branches which create capillary balls called glomeruli

Question 19

What is a nephron

Answer 19

Functional unit of the kidney

Question 20

Components of nephron

Answer 20

Corpuscle: glomerulus and capsule
Proximal convoluted tubule
Nephron loop (of Henle)
Distal convoluted tubule
Collecting ducts

Question 21

Nephrons form urine from three processes

Answer 21

Filtration, reabsorption, secretion

Question 22

Filtration

Answer 22

Movement of substances from blood to capsular space

Question 23

Reabsorption

Answer 23

Movement of substances from tubular fluid back to blood

Question 24

Secretion

Answer 24

Movement of substances from the blood to the tubular fluid

Question 25

Structure of renal corpuscle

Answer 25

Renal corpuscle is made of glomerulus and glomerular capsule Glomerulus is a tangle of capillaries that extend from the afferent arteriole The glomerular capsule surrounds the glomerulus

Question 26

Structure of glomerular capsule

Answer 26

Made of two layers: visceral and parietal Parietal layer made of simple squamous epithelium Visceral layer is adhered to glomerulus and is made of podocytes Capsular space lies between two layers and collect filtrate

Question 27

Glomerular development

Answer 27

The developing glomerulus presses into the renal tubule to form a visceral and parietal layer This forms a space separating the layers which is where filtrate will collect and drain into proximal convoluted tubule

Question 28

Layers of the filtration membrane

Answer 28

1. Epithelium of the glomerulus 2. Basement membrane of the glomerulus 3. Visceral layer of the glomerular capsule

Question 29

Function of filtration membrane

Answer 29

Allows only smallest solutes to exit glomerulus Solutes are pressed out of blood due to high pressure in the glomerulus Non selective method of filtration

Question 30

Characteristics of proximal convoluted tubule

Answer 30

Simple cuboidal epithelium with microvilli help increase reabsorption capacity Actively reabsorbs glucose, amino acids, electrolytes, and plasma proteins

Question 31

Characteristics of nephron loop (of henle)

Answer 31

Loops down into middle Primary function is to reabsorption water and solutes to bloodstream Made of two limbs: Each limb has thick and thin portion Thick and thin regions are made of different epithelium which will function in the reabsorption or secretion of different substances

Question 32

Characteristics of distal convoluted tubule

Answer 32

Simple cuboidal epithelium with sparse microvilli Primary function is to secrete ions (K+) into tubular fluid and also to reabsorb water

Question 33

Blood flow around the nephron

Answer 33

Peritubular capillaries surround the proximal and distal convoluted tubules Vasa recta surround the nephron loop

Question 34

Types of nephrons

Answer 34

Cortical nephrons: Work under normal conditions Juxtamedullary nephrons: work during periods of high activity

Question 35

Regulation of collecting tubules

Answer 35

Act under influence of anti-diuretic hormone (ADH) and aldosterone to limit the loss of water and sodium ions from blood

Question 36

Purpose of anti-diuretic hormone (ADH)

Answer 36

Released in response to dehydration Triggers conversion of water and sodium ions

Question 37

Purpose of aldosterone

Answer 37

Increases blood ion concentrations and blood volume Functions to increase amount of water in blood by increasing amount of sodium present

Question 38

Characteristics of juxtaglomerular apparatus

Answer 38

Group of cells that control production of aldosterone Made of: Macula dense cells in the Distal convoluted tubule JG cells in afferent arteriole Macula dense and JG cells communicate to regulate the blood fluid volume (blood pressure)

Question 39

Action of the juxtaglomerular apparatus

Answer 39

Macula densa cells in the DCT monitor the sodium ion concentration in the filtrate If ion concentration is too high, macula densa cells tell JG cells to contract Contraction narrows the wall of the afferent arteriole, reduces the pressure inside the glomerulus

Question 40

Effect of renin

Answer 40

Triggering of JG cells also releases renin Renin stimulates the production of aldosterone Aldosterone will act upon the collecting duct to make it more permeable to water Water is the secreted from the duct and reabsorbed back into the blood

Question 41

Overall mechanism of the juxtaglomerular apparatus

Answer 41

Macula densa cells sense an increase in Na+ concentrations in filtrate Macula densa stimulates JG cells to contract the afferent arteriole and release renin Contraction reduces flow of filtrate in PCT, thus retaining more water and Na+ Renin triggers aldosterone Aldosterone stimulates reabsorption of Na from collecting duct back to blood Increase in sodium ions in the blood will increase the reabsorption of water from filtrate Result is increase in blood volume/pressure

Question 42

How does urine exit the kidney

Answer 42

Through ureter Ureters carry urine into pelvic cavity to empty into urinary bladder Ureters insert in the posterolateral wall of the bladder A one way valve prevents urine from re-entering the ureter

Question 43

Where do kidney stones occur

Answer 43

Ureters are narrow in the lower pole of the kidney, iliac vessels, and entrance of the bladder These are locations where kidney stones are most likely to get stuck as they travel through the ureter

Question 44

Three layers of the ureter

Answer 44

1. Mucosa (transitional epithelium) 2. Muscularis (smooth muscle layers) 3. Adventitia (collagen and elastic fibers)

Question 45

Sine (without) uterine pelvic contents

Answer 45

Bladder, rectum, ureters

Question 46

Uterine pelvic contents

Answer 46

Uterus, rectum, bladder, ureters

Question 47

Four layers of urinary bladder

Answer 47

1. Mucosa (transitional epithelium) 2. Submucosa (dense, irregular connective tissue) 3. Muscularis (detrusor muscle) 4. Adventitia (outer loose connective tissue)

Question 48

Epithelium components of the bladder

Answer 48

Transitional epithelium allows the epithelium to stretch Mucosal folds called rugae allow for increased storage within the bladder Trigone is a triangular area formed by the entrance of the ureters and the formation of the internal urethral sphincter

Question 49

Characteristics the urethra

Answer 49

Urethra is made from smooth muscle of the bladder Internal urethral sphincter is also made of smooth muscle and is under autonomic control The distal end of the urethra is surrounded by the skeletal muscle forming the external urethral sphincter

Question 50

The difference between male and female urethrae

Answer 50

Male includes prostatic urethra following bladder, then membranous urethra, and finally penile urethra Female has external urethral orifice following bladder

Question 51

Micturition reflex center in brain

Answer 51

1. Stretch receptors in the bladder trigger the micrurition reflex center 2. Impulses travel to the detrusor muscle and the internal urethral sphincter 3. Smooth muscle in internal urethral sphincter relaxes 4. Smooth muscle in detrusor contracts 5. Person must consciously relax the external urethral sphincter

Question 52

Parasympathetics of the bladder

Answer 52

Stimulate micturition

Question 53

Sympathetics to the bladder

Answer 53

Inhibit micturition