Bs Excretory Systems

Front 1

Urea

Back 1

Carrier of excess Nitrogen from protein breakdown, since Nitrogen in form of ammonia is toxic.

Front 2

1. Skin consists of
2. Skinis controlled by

Back 2

1. ions, water, & urea
2. not controlled by amount of waste that needs to be excreted, but by temperature and level of sympathetic nervous system activity.

Front 3

1. What is kidney?
2. What do kidneys excrete?

Back 3

1. A sensitive regulator that must keep concentration @ optimal levels. Variation greater than 15% is fatal due to dysfunction of cells.
2. Urea, Na+, bicarbonate, & water.

Front 4

Function of the kidneys

Back 4

Homeostatic role: consistancy of physiological variables.
1. excrete hydrophilic wastes
2. maintenance of constant solute concentration, pH, and fluid volume.
**constant fluid volume important for blood pressure & cardiac output.

Front 5

3 steps in kidney role

Back 5

1. filtration
2. selective reabsorption
3. concentration/dilution

Front 6

Filtration

Back 6

high blood/filtration pressure @ glomerulus. Cells & proteins remain in blood, water & small waste products go into renal tubule.
*filtrate --> urine

Front 7

Selective reabsorption

Back 7

takes back useful items (glucose, water, a.a.) at proximal tubule, close to Bowman's capsule.
*Not regulated, the rate should be constant.

Front 8

Concentration/dilution

Back 8

conc/dil of urine @ distal tubule, close to collecting duct. Regulated by ADH (fluid volume) and aldosterone (Na+)

Front 9

Where blood enters and returns in the circulatory system

Back 9

blood enters renal artery (lower portion of aorta). Purified blood returns by large renal vein (inferior vena cava)

Front 10

The passage of urine.

Back 10

collecting duct --> papillae (tips of pyramid where urine leaves medulla) --> calyx (gaps between pyramids) --> renal pelvis (basin-like area inside kidney) --> ureter --> bladder

Front 11

2 things nephron consists of.

Back 11

1. Renal tubule: receives filtrate at one end, empties to collecting duct.
2. Blood vessels that carry arterial blood to tubule and filtered blood from tubule.

Front 12

The path blood travels in nephron

Back 12

Afferent arteriole --> glomerulus --> glomerular basement membrane --> Bowman's capsule --> proximal tubule --> Loop of Henle (descending limp) --> Loop of Henle (ascending limp) --> distal tubule --> collecting duct

Front 13

What happens to large molecules in afferent arteriole?

Back 13

they can't pass thru glomerulus, thus not filtered. They flow to efferent arterioles.

Front 14

Proximal convoluted tubule

Back 14

Near Bowman's capsule where selective reabsorption occurs. Chooses what to absorb, but the amount is not regulated.
Most filtered water, glucose, & a.a. are reabsorbed here.

Front 15

Distal convoluted tubule

Back 15

Near collecting duct where appropriate urine volume and osmolarity adjustments are made. Controlled by 2 hormones: ADH and aldosterone.

Front 16

ADH (Antidiuretic hormone)

Back 16

released by [posterior pituitary],
1. Prevents diuresis (waterloss in urine) by increasing water reabsorption.
2. Ultimately makes distal tubule permeable to water (w/o ADH, water impermeable).

Front 17

1. When is ADH secreted?
2. What is its result?

Back 17

1. secreted as plasma volume decreases and/or osmolarity increases.
2. result: concentrated urine and dilute blood.

Front 18

How does osmolarity affect water flow?

Back 18

Water flows out of the tuble because renal medulla has a very high osmolarity, which causes water to exit the tubule by osmosis.

Front 19

Aldosterone

Back 19

Released by [adrenal cortex] when blood pressure is low. Causes increased reabsorption of Na+ by distal nephron.

Front 20

What is the result of Aldosterone secretion?

Back 20

Increased plasma osmolarity: increase in thirst and water retention, thus increased blood pressure and volume.

Front 21

How are ADH and Aldosterone related?

Back 21

Aldosterone causes Na+ reabsorption, which increases plasma osmolarity. Then ADH causes water reabsorption.

Front 22

What parts of nephron are located in renal cortex (outer layer of kidney)?

Back 22

Bowman's capsule and proximal/distal convoluted tubule.

Front 23

1. Describe Loop of Henle
2. Name 3 types of limbs of Loop of Henle.

Back 23

1. Dips down into renal medulla (inner part of kidney)
2. Descending limb, thin ascending limb, & thick ascending limb.

Front 24

Function of the three limbs of Loop of Henle

Back 24

1. Descending: permeable to H2O, but not to ions. Water exits and filtrate becomes concentrated.
2. Thin ascending: not permeable to H2O, but loses ions from high-osmolarity filtrate.
3. Thick ascending: transports salt out of filtrate by active transport. Medulla becomes very salty, thus sucking out water from collecting duct by osmosis. That's why urine has higher osmolarity than plasma.

Front 25

Describe Vasa Recta and compare it to Loop of Henle

Back 25

blood vessels wrapped around Loop of Henle. Flows in countercurrent direction of filtrate inside Loop of Henle, making it easier to pick up water and other molecules.

Front 26

Juxtaglomerular apparatus (JGA)

Back 26

Specialized contact point between juxtaglomerular (JG) cells in afferent arteriole and macula densa in distal tubule.

Front 27

Juxtaglomerular (JG) cells

Back 27

When there's a decrease in blood pressure, secretes renin (enzyme) that ultimately catalyzes Angiotensin II, which increases blood pressure & stimulates a release of aldosterone.

Front 28

2 functions of macula densa

Back 28

When filtrate osmolarity decreases, it
1. stimulates JG cells to release renin, thus increasing blood pressure.
2. causes dilation of afferent arteriole, thus increase in blood flow

Front 29

plasma pH and its relation to urine

Back 29

1. when plasma pH is high, HCO3- (basic) is excreted as urine.
2. when pH is low, H+ (acidic) is excreted.

Front 30

Carbonic anhydrase

Back 30

An enxyme that catalyzes conversion of CO2 into H2CO3, that splits into HCO3- and H+.
**renal pH adjustment is very slow. Very fast in lung.