Osmoregulation

Question 1

3 reasons why water is important?

Answer 1

○ All animals are mostly water and all food is mostly water
○ Enzymatic reactions much be done in an aqueous environment
- Gas exchange in the lungs requires water

Question 2

Osmolarity

Answer 2

Concentration of all solutes in a liquid measured in milliosmoles (mOsM)

Question 3

Bloods total and highest solute concentrations

Answer 3

Total is ~300mOsM, highest is sodium at ~140mOsM

Question 4

Seawater and Freshwater Osmolarities

Answer 4

Seawater ~1000mOsM
Freshwater <5mOsM

Question 5

In marine environments, animals tend to gain _______ and lose ________

Answer 5

Salts, water

Question 6

Freshwater animals tend to gain ______ and lose ______

Answer 6

Water, salts

Question 7

Terrestrial animals tend to lose ______

Answer 7

Water

Question 8

Isosmotic Definition and Effects on the Cell

Answer 8

Concentration of solutes outside of the cell is equal to concentration of solutes inside the cell; there is no effect on the cell

Question 9

Hyperosmotic Definition and Effects on the Cell

Answer 9

Concentration of solutes outside of the cell is greater than concentration of solutes inside the cell; water leaves the cell/solute enters causing it to shrivel up

Question 10

Hypo-Osmotic Definition and Effects on the Cell

Answer 10

Concentration of solutes outside of the cell is less than concentration of solutes inside the cell ; water going into the cell/solute leaves and may cause it to burst

Question 11

Osmoconformers

Answer 11

Change their bodies osmolarity similar to their environment (many invertebrates)

Question 12

Osmoregulators

Answer 12

Osmolarity is constant regardless of the environment (most vertebrates)

Question 13

Ionoconformers

Answer 13

Exert little control over ion profile within the extracellular space (many invertebrates)

Question 14

Ionoregulators

Answer 14

Control ion profile within their extracellular space (most vertebrates)

Question 15

How do freshwater fish deal with changing osmolarities/ionic changes in their environments?

Answer 15

Freshwater fish gain water and lose salt, and they solve this problem by ejecting water via urine that is mostly water from its kidneys

Question 16

How do saltwater fish deal with changing osmolarities/ionic changes in their environments?

Answer 16

Saltwater fish are always gaining salt and losing water, and they fix this via urine that is very concentrated with salt

Question 17

4 characteristics that make transport unique for epithelial cells

Answer 17

1. Asymmetrical distribution of membrane transports
   a. Solutes are selectively transported across membrane
   
   2. Cells interconnected to form impermeable sheet of tissue
      a. Little leakage between cells
   3. High cell diversity within tissue
   4. Abundant mitochondria
      Large energy (ATP) supply

Question 18

Transcellular transpor

Answer 18

Movement through the cell across membranes

Question 19

Paracellular transport

Answer 19

Movement between cells

Question 20

Types of transporters

Answer 20

○ Na+/K+ATPase
§ Can be with or against the gradient
○ Ion Channels (Cl-, K+, Na+)
§ Ion channels are not energy dependent
§ Move with concentration gradient
○ Electroneutral Cotransporters
§ Transfer ions of opposite charges to flow in the same direction
○ Electroneutral exchangers
- Transfer ions of opposite charge to flow in opposite direction

Question 21

How to terrestrial animals reduce water flux

Answer 21

○ They cover external surfaces with layer of hydrophobic molecules (oils)
§ Mucus (amphibians, frogs, salamanders, etc.)
§ Cornified stratum corneum with keratin
□ Hard outer layer (turtle shell, hair, feathers)
□ Terrestrial amniotes
□ Also sebaceous tissues
§ Cuticle with chitin
□ Arthropods
□ Shiny covering of beetles is covered with chitin

Question 22

Integumentary System

Answer 22

• Stratum corneum on the outside, under those are the corneocytes that replace them
  
  • Next is keratinocyte
    ○ Makes keratin
    ○ All of these are apart of the epidermis
  • Basement membrane is next
• Blood vessels (dermis) is last

Question 23

Sources of water for terrestrial animals

Answer 23

• Diet, including the water in food
  
  • Metabolic water
    
    • Water generated as a final step in oxidative phosphorylation (we don’t get much from this)

Question 24

Ammonioteles

Answer 24

(typically aquatic) animals that make most of their nitrogenous waste in the form of ammonia

Question 25

Urioteles

Answer 25

(typically terrestrial) animals that make most of their nitrogenous waste in the form of uric acid

Question 26

Ureoteles

Answer 26

(typically terrestrial) animals that make most of their nitrogenous waste in the form of urea

Question 27

Ammonia

Answer 27

□ Ammonia is released by deamination of amino acids
□ Requires little energy to produce
® 1 ATP is used and 1 N released
□ Disadvantages are that it is highly toxic and requires large volumes of water to store and excrete (why)
- Dissolves well in water

Question 28

Uric Acid

Answer 28

§ Doesn’t dissolve well but is not dangerous
§ Except for gout and kidney stones
§ Excretion
□ Advantages
® Few toxic effects
® Can be excreted in small amounts of water
□ Disadvantages
® Expensive to produce
◊ Takes a lot of ATP to make uric acid (7-8x more than ammonia)

Question 29

Urea

Answer 29

§ Fairly soluble, not very dangerous
§ Excretion
□ Advantages
□ Only slightly toxic
□ Relatively inexpensive to produce
§ Disadvantages
□ Urea is a perturbing solute

Question 30

Vertebrate kidneys have six roles in homeostasis

Answer 30

○ Ion balance
○ Osmotic balance
○ Blood pressure
○ pH balance
○ Excretion of metabolic wastes and toxin
- Hormone production

Question 31

Ureters

Answer 31

Two tubes that drain the urine produced from the kidneys to the bladder

Question 32

Calyx

Answer 32

Urine is collected here and then goes to the ureter

Question 33

Renal Pyramid

Answer 33

Is divided into the renal medulla (interior) and the renal cortex (exterior)

Question 34

Nephron

Answer 34

Functional unit of the kidney with the goal of processing waste products from the blood to create urine

Question 35

Glomerulus

Answer 35

□ Ball of capillaries
® Where transport of nutrients and water takes place, afferent blood leaves from here
® Surrounded by Bowman’s capsule
® Blood pressure forces fluid from the blood in the glomerulus into the bowman’s capsule, thereon it is called the filtrate

Question 36

Four Processes of the Nephron

Answer 36

§ Filtration: Filtrate of blood formed at glomerulus at the bowman’s capsule
§ Reabsorption: Specific molecules in the filtrate removed (reabsorbed into the body)
§ Secretion: Specific molecules added to the filtrate
§ Excretion: Urine is excreted from the body

Question 37

What solutes does the filtrate contain when it is in bowman’s capsule?

Answer 37

glucose, water, amino acids, salts, H+, bicarbonate ions, vitamins, urea, etc.

Question 38

Solute Movement in the proximal tubule

Answer 38

NaCl and water move to the interstitial fluid (reabsorption)
○ Glucose, amino acids, potassium, and bicarbonate are reabsorbed
○ There are still some concentrations of these in the filtrates
○ H+ and NH4+ ions are secreted into the tubule

Question 39

Solute movement in loop of Henle descending limb

Answer 39

○ Water is reabsorbed through aquaporins
○ Descending limb does not have channels for most solutes, like salt, so those are not reabsorbed, solute concentration continues to increase in the nephron

Question 40

Solute movement in loop of Henle ascending limb

Answer 40

○ No aquaporins, but there are proteins that allow NaCl to be reabsorbed in the thin segment (high to low concentration)
○ In the thick segment, NaCl is pumped out into the interstitial fluid by active transport

Question 41

Solute movement in the distal tubule

Answer 41

○ H+, ammonium, and potassium are secreted
○ NaCl, water, and bicarbonate are reabsorbed