Lecture 21- salt and water balance and nitrogen excretion

Question 1

What controls the volume, concentration and composition of extracellular fluids?

Answer 1

Excretory organs

Question 2

What is osmolarity?

Answer 2

The number of moles of active solutes per liter of solvent

Question 3

How do excretory organs control osmolarity and volume of extracellular fluids?

Answer 3

• Excretion of solutes in excess, NaCl, etc.

- Conserving valuable or short supply solutes- amino acids, glucose

Question 4

What are osmoconformers?

Answer 4

Equilibirate their osmolarity with sea water

Question 5

What is the osmolarity of the sea?

Answer 5

Very high, 300mosm/l

Question 6

What are osmoregulators?

Answer 6

Maintain osmolarities lower than sea water

Question 7

What animals are osmoconformers?

Answer 7

All vertebrate marine animals except sharks and rays

Question 8

Where are osmoregulators found?

Answer 8

Extreme conditions- freshwater (too few proteins etc in interstital fluid), evaporating tide pools

Question 9

What type of animal can be found in varied environments, including Utah’s great salt lake?

Answer 9

Brine shrimp - Artemia

2500 mosm/Liter

Question 10

How do brine shrimp live in such varied environments?

Answer 10

In high osmolarity- Cl- is actively transported out through gills (Na+ ions follow)
In low osmolarity, chloride ion transport is reversed

Question 11

What are ionic conformers?

Answer 11

Animals which allow their ionic composition to match their environment

Question 12

What are ionic regulators?

Answer 12

animals which conserve some ions and excrete others to maintain ionic composition

Question 13

Give an example of ionic regulators.

Answer 13

Some sea birds nasal glands excrete NaCl

Question 14

Carbohydrates and fat end as…

Answer 14

Water and CO2

Question 15

Proteins and nucleic acids end as…

Answer 15

nitrogenous waste

Question 16

What is the most common nitrogenous waste?

Answer 16

Ammonia (NH3)

Question 17

What is the name given to animals who secrete ammonia through their gills?

Answer 17

Ammonotelic

Question 18

What do terrestrial animals do with ammonia?

Answer 18

Convert it to urea or uric acid

Question 19

What name is given to animals which secrete urea?

Answer 19

Ureotelic animals

Question 20

What name is given to animals which secrete insoluble uric acid?

Answer 20

Uricotelic animals

Question 21

Most animals secrete more than one nitrogenous waste. Humans are ureotelic but also secrete:

Answer 21

• Uric acid from metabolism of nucleic acids and coffee

- Ammonia- regulates pH of extracellular fluid by buffering urine

Question 22

What is the main excretory organ in vertebrates?

Answer 22

The kidney

Question 23

What is the main functional unit of the kidney?

Answer 23

The nephron

Question 24

What do nephrons do?

Answer 24

Filter large volumes of blood and achieve bulk reabsoption

Question 25

What adaptations have bony fish made to their excretory systems in response to their environment?

Answer 25

Produce very little urine to conserve water | Do not absorb some ions in their gut

Question 26

How have cartilaginous fish adapted to conserve water?

Answer 26

Convert nitrogenous waste to compounds and retain large amounts of extracellular fluid with similar osmolarity to sea water

Question 27

How do amphibians maintain salt and water balance?

Answer 27

-Reduced permeability of their skin to water -Estivation: a state of low metabolic activity and low water demand Some frogs fill a large bladder with water before estivation

Question 28

What three adaptation enables reptiles to live outside of water?

Answer 28

- Amniotic reproduction: shelled eggs - Scaled epidermis that retards water loss - Excretion of uric acid with little water loss

Question 29

How have birds and mammals adapted to conserve water?

Answer 29

- Surface coverings - Amniotic reproduction - Birds produce uric acid - Both can produce concentrated urine

Question 30

What is the first step in urine formation in vertebrate nephrons?

Answer 30

-Filtration: blood is filtered in a glomerulus (a ball of capillaries)

Question 31

What happens after filtration in the glomerulus?

Answer 31

Tubular reabsorption: Glomerular filtrate flows into renal tubule where it is modified by reabsorption of specific nutrients, ions and water

Question 32

What happens after tubular reabsoption in the renal tubule?

Answer 32

Tubular secretion: glomerular filtrate is further modified when tubule cells transport subtances to be excreted into the tubular contents

Question 33

What transports substances to and from the renal tubules?

Answer 33

Peritubular capillaries

Question 34

Where does the glomerular filtrate go?

Answer 34

The Bowman's capsule

Question 35

How does blood enter the Nephron?

Answer 35

Through the afferent arteriole

Question 36

How does blood leave the glomerulus?

Answer 36

Through the efferent arteriole

Question 37

What does the efferent arteriole become?

Answer 37

The peritubular capillaries

Question 38

What are podocytes?

Answer 38

Capsule cells that contact the glomerular capillaries- fine processes wrap around the capillaries

Question 39

Why is the rate of filtration high in the glomerulus?

Answer 39

- High capillary blood pressure | - High permeability of glomerular capillaries and their podocytes

Question 40

What is the name of the duct that leads from the kidney to the urinary bladder?

Answer 40

The uretar

Question 41

What is the name given to the tube for urine excretion?

Answer 41

Urethra

Question 42

On what side does the uretar, renal artery and renal vein enter the kidney?

Answer 42

On the concave side

Question 43

What does the uretar branch and envelop?

Answer 43

Kidney tissues called Renal pyramids

Question 44

What do renal pyramids make up?

Answer 44

The medulla (inner core)

Question 45

What is the outer layer of the medulla?

Answer 45

The cortex

Question 46

What surrounds the base of the urethra?

Answer 46

Two sphincter muscles- one controlled by the autonomic nervous system, the other voluntary.

Question 47

What is in the region between the medulla and cortex?

Answer 47

The renal artery divides into the many arterioles that serve the nephrons

Question 48

Where are all the glomeruli located?

Answer 48

In the cortex

Question 49

What is the initial segment of a renal tube called?

Answer 49

The proximal convoluted tube ('first','twisted')

Question 50

Where are all of the proximal convoluted tubes located?

Answer 50

In the cortex

Question 51

What happens to the renal tube as it descends into the medulla?

Answer 51

The convoluted tube becomes less convoluted, | Tubule makes a hairpin turn and ascends back out

Question 52

What is the hairpin turn of the renal tubule called?

Answer 52

The loop of Henle

Question 53

What does the ascending loop of Henle become when it reaches the cortex?

Answer 53

The distal convoluted tube (distal-further from glomerulus)

Question 54

What do the distal convoluted tubes join to become?

Answer 54

A collecting duct in the cortex

Question 55

Where do collecting ducts go?

Answer 55

They descend through renal pyramids and empty into the pelvis- pelvic divisions join and leave the kidney as the ureter

Question 56

How are blood vessels organised in the kidneys?

Answer 56

Regular arrangement, parallels that of nephrons

Question 57

What is the name given to the peritubular capillaries that are parallel to the loop of Henle and collecting duct?

Answer 57

The vasa recta

Question 58

How are all of the peritubular capillaries from all of the Nephrons arranged?

Answer 58

They all join into venules which lead to the renal vein

Question 59

What structure is responsible for most reabsoption of water and solutes?

Answer 59

The proximal convoluted tubule.

Question 60

How does the proximal convoluted tube maximize reabsoption?

Answer 60

- Microvilli increases surface area - Many mitochondria - Actively transport Na+, glucose and amino acids - Water follows transport of solutes

Question 61

How does urine become very concentrated?

Answer 61

Countercurrent multiplier mechanisms in the loops of Henle

Question 62

What is countercurrent multiplier mechanisms in the loops of Henle?

Answer 62

Tubule fluid flows in opposite directions in the ascending and descending limbs- loop increases osmolarity of interstital fluid in a gradual way

Question 63

What are the three loop of Henle segments?

Answer 63

- Thick ascending limb - Thin ascending limb - Thin descending limb

Question 64

What does the thick ascending limb do?

Answer 64

Active transport of sodium ions (chloride follows) and raises their concentration in interstital fluid

Question 65

What does the thin descending limb do?

Answer 65

Loses water to the neighboring interstital fluid with high sodium and chloride ions

Question 66

What does the thin ascending limb do?

Answer 66

Receives concentrated fluid from descending limb and allows sodium and chloride diffusion into interstital fluid

Question 67

What are aquaporins?

Answer 67

Membrane proteins abundant in highly water permable areas such as the PCT and decending loops of Henle

Question 68

What are the similarities between fluid in the collecting duct and the blood fluid?

Answer 68

Same concentrations | Different composition

Question 69

What is the major solute in the conducting duct?

Answer 69

Urea

Question 70

How do kidneys regulate blood pH?

Answer 70

Kidneys remove H+ and add HCO3- to the blood buffer system

Question 71

How is the blood buffer system formed?

Answer 71

hydration of CO2 followed by dissociation of carbonic acid

Question 72

What controls the acid levels in blood?

Answer 72

Lungs- add more CO2 | Kidneys add base portion

Question 73

What is the result of renal failure?

Answer 73

- High blood pressure because of salt and water - Uremic poisoning (too much urea) - Acidosis (metabolic acids)

Question 74

What does dialysis do?

Answer 74

Passes blood through membrane channels bathed in a plasma-like solution to remove wastes