Topic 6 Urine Formation overview

Question 1

Renal Function top reasons? (4)

Answer 1

• Regulation of water and electrolyte balances*
• Regulation of body fluid osmolality and electrolyte* concentrations
• Regulation of blood pressure*
• Regulation of acid-base balance

Question 2

Urea comes from ?

Answer 2

amino acid metabolism

Secreted in urine

Question 3

Creatinine comes from?

Answer 3

from muscle creatine

Creatine used to create phosphocreatine which serves as energy source for production of ATP in muscle. Each day 1 to 2% of muscle creatine converted to creatinine
Secreted in urine

Question 4

Uric acid comes from ?

Answer 4

from nucleic acids

Secreted in urine

Question 5

End products of hemoglobin break down to what?

Answer 5

bilirubin

Secreted in urine

Question 6

Fluid / salt intake usually depends on what?

Answer 6

individual eating / drinking habits

Question 7

Kidneys are able to respond to what levels of fluctuation of Na concentration with still small changes in ECF Vol? (mEq/day)

Answer 7

• 10 mEq/day to 1500mEq/day
• Able to respond to huge differences in sodium intake with relatively small changes in ECF volume or [Na+]
• Also true for most other electrolytes

Question 8

Kidneys work with what other systems for acid base regulation?

Answer 8

Lungs

Body Buffer Systems

Question 9

sulfuric and phosphoric acid come from what?

Answer 9

Byproducts of protein metabolism

Question 10

Acid base Regulation. what do Lungs and kidneys control?

Answer 10

-Lungs remove carbon dioxide
-Kidneys control hydrogen ion and bicarbonate
concentration and only way to remove sulfuric and phosphoric acid

Question 11

Almost all erythropoietin is secreted from where?

Answer 11

Kidney

which stimulates red blood cell production by hematopoietic stem cells in bone marrow

Question 12

What is a major stimulus for Erythropoietin production?

Answer 12

hypoxia

Question 13

Patient’s with severe renal disease will develop what bc of lack of production of erythropoietin?

Answer 13

severe anemia due to lack of erythropoietin production

Question 14

Glucose Synthesis occurs when?

Answer 14

• During prolonged fasting

- Significant quantities can be produced from kidneys

Question 15

Gluconeogenesis (aka glucose synthesis)

Answer 15

-Kidneys synthesis glucose from amino acids and other precursors during fasting

Question 16

Glomerular Capillaries - high hydrostatic pressure produces/causes what? what mmHg?

Answer 16

High pressure (60mmHg) produces high/rapid
rate of fluid filtration

Question 17

Peritubular Capillaries - low hydrostatic pressure produces/permits what? what mmHg

Answer 17

Low pressure (13 mmHg) produces high/rapid
rate fluid reabsorption

Question 18

Each kidney weighs what approx? gms

Answer 18

150 grams

Question 19

By adjusting the resistance of afferent and efferent arterioles the kidneys can regulate what?

Answer 19

hydrostatic pressure in both glomerular and peritubular capillaries this changing glomerular filtrate and tubular reabsorption.

Question 20

Peritubular capillaries empty into what?

Answer 20

vessels of venous system

Question 21

% of all nephrons that are juxtamedullary nephrons?

Answer 21

20 to 30% of all

Question 22

Each kidney contains how many nephrons?

Answer 22

800,000-1 million nephrons

Question 23

After age 40 what happens to the # of nephrons?

Answer 23

lose 10% every 10 years

Question 24

Each nephron contains what two things>

Answer 24

1) glomerulus - where fluid filtered (tuft of glomerular capillaries)
2) Long tubule - where filtered fluid is converted into urine

Question 25

Micturition - what kind of reflex?

Answer 25

An Autonomic reflex but can be inhibited/facilitated by centers in cerebral cortex or brain stem (voluntary)

Question 26

what is Micturition?

Answer 26

process by which bladder empties when it becomes filled

Question 27

Detrusor muscle - type of muscle?

Answer 27

smooth muscle chamber | muscle fibers go in all directions

Question 28

Urinary bladder inner lining what?

Answer 28

rugae

Question 29

Trigone

Answer 29

above bladder neck | its inner mucosa (lining) is smooth

Question 30

Micturition 2 steps?

Answer 30

1. Bladder fills, tension rises above threshold level | 2. A nervous reflex (micturition reflex) empties bladder or causes conscious desire to pee

Question 31

Bladder Innervation, main supply of nerves come from ?

Answer 31

Pelvic nerves

Question 32

Pelvic nerves

Answer 32

sensory nerve fibers - detect stretch | motor nerve fibers - parasympathetic fibers

Question 33

Pudendal nerve

Answer 33

Skeletal motor fibers come thru this nerve to the ext. sphincter. –skeletal muscle fibers provide Somatic (voluntary) control of external sphincter

Question 34

Sympathetic control (innervation) of bladder via what nerves?

Answer 34

- hypogastric nerves | - Control mainly the blood vessels (as opposed to controlling contraction.

Question 35

Ureters well supplied with what type of nerves?

Answer 35

pain nerves

Question 36

Ureterorenal Reflex stimulated by what?

Answer 36

pain impulses in ureters causing a sympathetic reflex back to kidney to constrict renal arterioles thereby decreasing U.O. from kidney. Important for preventing excessive flow of fluid into pelvis of a kidney w/a blocked ureter

Question 37

Stimulated when blocked ureters respond with intense reflex constriction which sends sympathetic stimulation back to kidneys to constrict renal arterioles

Answer 37

Ureterorenal Reflex

Question 38

prevents excessive flow of fluid into pelvis of a kidney w/a blocked ureter

Answer 38

Ureterorenal Reflex

Question 39

Renal calyces act as what?

Answer 39

pacemaker for peristaltic contraction of smooth muscle forcing urine down into the renal pelvis, down the ureters into the bladder

Question 40

Increased stretch of calyces increases what rate?

Answer 40

peristaltic rate

Question 41

Parasympathetic innervation does what to peristalsis (peristaltic contractions in Ureter)?

Answer 41

enhances peristalsis (peristaltic contractions in Ureter)

Question 42

sympathetic innervation does what to peristalsis (peristaltic contractions in Ureter)?

Answer 42

inhibits peristalsis (peristaltic contractions in Ureter)

Question 43

The normal tone of the detrusor muscle does what?

Answer 43

Prevents backflow from bladder to ureters, aka REFLUX, esp when a person builds up in bladder during micturition or bladder compression (aka esp during bladder contraction)

Question 44

If ureter is not long enough to pass through wall of bladder, what will occur?

Answer 44

reflux

Question 45

Peristaltic waves down/along ureter increases pressure within ureter to do what to bladder?

Answer 45

to open passage to bladder | so region passing through bladder wall opens and allows urine to flow

Question 46

Urination occurs when inhibitor signals are stronger than what signals to do what?

Answer 46

voluntary constrictor signals being sent to external sphincter

Question 47

Micturition contractions stimulated by what?

Answer 47

stretch receptors/reflex, initiated by sensory stretch receptors in bladder wall Provides positive feedback to stretch receptors resulting in further increase in pressure

Question 48

What are micturition contractions ?

Answer 48

Tonic pressure changes during filling of the bladder, periodic acute increase in pressure that last sec-min, caused by micturition reflex.

Question 49

As bladder fills more and more what happens to the micturition reflex?

Answer 49

inhibited time decreases (more frequent contractions) and resulting contractions become more powerful

Question 50

Once micturition reflex is strong enough it stimulates inhibitor signals to where?

Answer 50

the external sphincter

Question 51

Once Micturition Reflex begins it is what?

Answer 51

"Self regenerative" initial contraction activates stretch receptors to cause a greater increase in sensory impulses, cycle of contractions repeat until there is a strong degree of contractions After a while it starts to fatigue and permits bladder relaxation for some time and than starts again.

Question 52

Internal sphincter–tone

Answer 52

holds urine in bladder | smooth muscle

Question 53

External sphincter

Answer 53

–skeletal muscle –voluntary control by nervous system –conscious prevention of urination