Physiology Urinary System

Front 1

What are the functions of the Urinary System?

Back 1

Removal of wastes from the blood
Regulates the composition of the blood
Transports, Stores and eliminates the urine

Front 2

What are the organs of the urinary system?

Back 2

Kidneys, Ureters, Urinary Bladder, Urethra

Front 3

How many nephrons does each kidney have?

Back 3

over 1 million

Front 4

What is a nephron?

Back 4

Any of the numerous filtering units of the vertebrate kidney that remove waste matter from the blood.

Front 5

What happens to the blood pressure within the glomerulus during glomerular filtration?

Back 5

It forces fluids and solutes from the blood into the glomerular capsule

Front 6

Describe the composition of the filtrate

Back 6

It is similar to plasma except it has LESS protein

Front 7

What is GFR (Glomerular Filtration Rate)?

Back 7

The amount of fluid filtered from blood into the glomerulus per minute

Front 8

What is the GFR dependent upon?

Back 8

NFP (net filtration pressure)
Permeability of filtration membrane
Surface area of filtration membrane

Front 9

Describe the autoregulatory control of the GFR

Back 9

Decrease in BP/Decrease in GFR
Inhibit JGA
Inhibit Vasoconstrictor substance
dilation of afferent arterioles
Stimulate NFP (net filtration pressure)
Increase GFR

Front 10

Describe the hormonal control of the GFR

Back 10

Decrease in BP/Decrease in GFR
Stimulate JGA
Produce Renin
Converts angiotensin I into angiotensin II

Front 11

Describe the first effect of angiotensin II

Back 11

Constricts efferent arterioles
Stimulates NFP
Increases GFR

Front 12

Describe the second effect of angiotensin II

Back 12

Stimulates the adrenal cortex which
Secretes aldosterone
Stimulates Sodium and Water retention
Increases Blood Volume
Increases BP
Increases GFR

Front 13

Describe the third effect of angiotensin II

Back 13

Stimulates the thirst center in the hypothalamus
Increase fluid intake
Increase blood volume and BP
Increase NFP
Increase GFR

Front 14

Describe the fourth effect of angiotenstin II

Back 14

Stimulates the posterior pituitary which
Secretes ADH
Stimulating Water reabsorption
Increases Blood volume and BP
Increases NFP
Increases GFR

Front 15

Describe the nervous control of the GFR

Back 15

Stress causes the stimulation of the Sympathetic NS
Constriction of afferent arterioles
Inhibit blood flow
Decrease GFR

Front 16

What is Tubular Reabsorption?

Back 16

The process by which substances are returned to the blood FROM the filtrate

Front 17

Where does Tubular Reabsorption occur?

Back 17

Mostly in the PCT (proximal convoluted tubule) but also in the loop of Henle, DCT, and Collecting Duct

Front 18

What is reabsorbed by osmosis during tubular reasbsorption?

Back 18

Water (99.3% or 178.5 L/day)

Front 19

How much water is reabsorbed by each stage during tubular reabsorption?

Back 19

PCT-108L
Loop of Henle-45L
DCT-9L
Collecting Duct-16.5L

Front 20

What is ACTIVELY reabsorbed during tubular reabsorption?

Back 20

99-100% of Organic Nutrients
(glucose, amino acids, monosaccharides, etc)
Cations (Na+, K+, calcium, etc)

Front 21

What is PASSIVELY reabsorbed during tubular reabsorption?

Back 21

Anions (chloride)

Front 22

What is tubular secretion?

Back 22

Process by which substances are passed from the blood into the filtrate

Front 23

Where does tubular secretion occur?

Back 23

Mostly in the DCT and collecting ducts. Some in PCT

Front 24

What is removed during tubular secretion?

Back 24

Excess Potassium Ions
Hydrogen Ions (blood pH regulation)
Wastes (urea, uric acid, creatine and ammonia)

Front 25

What is countercurrent multiplication?

Back 25

The process by which a high sodium concentration within the medulla is established and maintained which is necessary for the production of a concentrated urine

Front 26

What does the Ascending Loop of Henle actively transport to the interstitial spaces of the medulla?

Back 26

The Ascending Loop of Henle Actively transports sodium from the filtrate into the interstitial spaces of the medulla

Front 27

Describe the concentration levels

Back 27

Highest at bottom, lowest at top because there is less and less sodium ions to transport as the filtrate moves up

Front 28

What is the ascending loop impermeable to?

Back 28

Water. Water does not move in or out

Front 29

What is the decending loop of henle impermeable to?

Back 29

Sodium

Front 30

What is the decending loop of henle permeable to?

Back 30

Water

Front 31

How does water move from the filtrate into the interstitial spaces of the medulla?

Back 31

By Osmosis

Front 32

What is Countercurrent Exchange?

Back 32

The process by which high sodium concentration in the interstitial spaces of the medulla are maintained

Front 33

What does Countercurrent Exchange involve?

Back 33

It involves the vessels of the vasa recta

Front 34

Describe the location of the vessels of the vasa recta and some of their properties

Back 34

They overlay the loop of henle and are freely permeable to both water and sodium

Front 35

The descending loop ________ sodium and ________ water passively

Back 35

gains, losses

Front 36

The ascending loop ________ water and __________sodium passively

Back 36

gains, losses

Front 37

What is the net result of Countercurrent Multiplication?

Back 37

That the blood's osmolarity does not change and sodium remains within the interstitial spaces of the medulla

Front 38

When is Urine dilute?

Back 38

Urine is dilute under normal circumstances

Front 39

Describe the control of urine volume/concentration

Back 39

Increase in blood osmolarity
stimulate hypothalamus
stimulate posterior pituitary
Stimulate ADH Secretion
Increase water reabsorption by the collecting ducts
Decrease urine volume and urine concentration

Front 40

What are the components of Urine?

Back 40

Water (95%)
Organics-urea, uric acid, creatine
Inorganics-sodium, chloride, potassium, ammonia

Front 41

What are the Characteristics of Urine?

Back 41

1-1.8 L/day secreted if properly hydrated
Light yellow to amber (depending on fluid intake)
Transparent to stlightly turbid
Aromatic (if allowed to stand)
pH= 6 (but can range from 4.5-8.0)
Specific Gravity=1.008-1.030

Front 42

What is the function of the Ureters?

Back 42

Transports urine from the kidneys to the urinary bladder

Front 43

What moves the urine into the bladder?

Back 43

Peristaltic Waves (every 30 seconds)

Front 44

What is the function of the Urinary Bladder?

Back 44

Storage and expulsion of the Urine

Front 45

Describe the function of micturition

Back 45

A) Bladder stretches as it fills (200ml)
Stimulate baroreceptors in walls
Desire to urinate, constriction of bladder and opening of internal sphincter
B) Cerebral cortex opens external sphincter
C) as a result of A & B, urine is forced into the urethra and out

Front 46

What does the Urethra transport in females?

Back 46

Transports Urine from the bladder to the outside

Front 47

What does the Urethra transport in males?

Back 47

Transports Urine and Semen to the outside