Ion and Water Balance Flashcards

1
Q

Whats osmoregulation?

A

Regulation of ion and water balance

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2
Q

What are 2 different strategies to meet ionic challenges?

A
  • Osmoconformer – internal osmolarity = external osmolarity
  • Osmoregulator – regulate equilibrium
  • Active regulation of the osmotic pressure of an organism’s body fluids, detected by osmoreceptors, to maintain the homeostasis
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3
Q

What are 2 salt tolerances?

A

Stenohaline - able to tolerate only a narrow range of salinity.
Euryhaline – able to tolerate a wide range of salinity

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4
Q

What is osmolarity? Of sw sharks, sw cod, and fw perch?

A

Measures the body’s electrolyte-water balance

-Sharks- Seawater: 1200 mOsM
shark plasma osmolarity: 1200 mOsM, but [salt] &laquo_space;SW Isomotic

-Cod- Seawater: 1200 mOsM
Cod plasma osmolarity: 350 mOsM hyposmotic

  • Perch- Freshwater: < 10 mOsM
    Perch plasma osmolarity: 350 mOsM hyperosmotic
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5
Q

How do terrestrial animals obtain water?

A

Through diet or metabolism

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6
Q

What 3 levels can ion and water balance can be maintained at?

A
  1. Cells
  2. Epithelial tissues
  3. Kidney
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7
Q

What do epithelial tissues form?

A

Form boundary between animal and environment

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8
Q

What are keratinocytes in epithelial tissue?

A

Secrete proteins and lipids to form a dense hydrophobic extracellular matrix

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9
Q

What are 4 epithelial Tissue Properties for 
Ion Movement?

A
  1. Asymmetrical distribution of membrane transporters.
  2. Cells interconnected to form impermeable sheet of tissue. (junctions
  3. High cell diversity within tissue.
  4. Abundant mitochondria.
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10
Q

What are 2 routes of transport for solutes? What do they use?

A
1. Transcellular- 
travel through the cell, passing through both the apical membrane and basolateral membrane
2. Paracellular- 
passing through the intercellular space between the cells
*Use-Na+/K+ ATPase
	ion channels
	cotransporters
	exchangers
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11
Q

How is oxygen exchanged in fish gills?

A

Passes over the gills
Start= high o2
End=low o2

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12
Q

What are fish gill lamellae composed of?(3)

A

Mucous cells
Mitochondria-rich chloride cells
Pavement cells

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13
Q

What does ion transport in fish gills depend on?

A

Depends on water salinity

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14
Q

What fish can migrate between saltwater and freshwater? How?

A
  • Diadromous fish

- Smoltification- physiological changes

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15
Q

What are salt glands? Who has them?

A
  • Excrete hyperosmotic solutions of Na+ and Cl-
  • Hyperosmotic solutions produced by ion pumps and a countercurrent multiplier
  • Reptiles and birds
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16
Q

How is nitrogen excreted (three forms)?

A
  1. Ammonia
  2. Uric acid
  3. Urea
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17
Q

What are ammonia excretion advantages and disadvantages?

A

Ad- Little E to produce

Dis- Toxic; must be excreted in lots of water

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18
Q

What are uric acid excretion advantages and disadvantages?

A

Ad- Little water excreted with it and low toxicity

Dis- Lots of E to produce

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19
Q

What are urea excretion advantages and disadvantages?

A

Ad-Less toxic= less water

Dis- A little more E to produce

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20
Q

What do Condricythyan fish use urea for?

A

To increase tissue osmolarity

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21
Q

What are the kidneys 6 roles in homeostasis?

A
  1. Ion balance
  2. Osmotic balance
  3. Blood pressure
  4. pH balance
  5. Excretion of metabolic wastes and toxins
  6. Hormone production
22
Q

What are the layers of the kidney?

A

Outer cortex

Inner medulla

23
Q

How does urine leave the kidney?

A
  • Urine leaves kidney via ureter

- Ureters empty into urinary bladder

24
Q

Whats the nephron in the kidney? Composed of what? Fluid movement?

A
  • Removes waste and produces urine
  • Renal tubule- Bowmans capsule, loop of henle
  • Vasculature- Glomerulus
25
Q

2 types of nephron?

A
  1. Cortica -glomeruli in the outer cortex; shorter loops of Henle, which dip only into the outer medulla
  2. Juxtamedullary- glomeruli near the corticomedullary border (concentrated urine)
26
Q

What happens in the renal tube?

A

-Fluid moves from lumen through proximal tubule, loop of Henle, distal tubule, collected in duct

27
Q

What happens in the vasculature?

A

Releases blood into the glomerulus.

28
Q

What are the 4 processes in urine production?

A

Filtration

Reabsorption

Secretion

Excretion

29
Q

Describe filteration in urine production.

A

Liquid components of the blood are filtered into Bowman’s capsule

Glomerular capillaries are very leaky- Fluid leaks into kidney tubes

The process of filtration that yields filtrate
-H20 and solutes in a fraction of blood plasma move across glomerular capillary walls (leaky) into Bowman’s capsule, then into the renal tubule system.

30
Q

Describe reabsorption in urine production.

A
  • Primary urine- Initial filtrate filtered in Bowman’s capsule that is isosmotic to blood ~300 mOsM
  • Most water and salt in primary urine reabsorbed using transport proteins and energy
  • nephron removes water and solutes from the tubular fluid (pre-urine) and returns them to the circulating blood
31
Q

Whats the renal threshold?

A

Concentration of a substance dissolved in the blood above which the kidneys begin to remove it into the urine.

32
Q

Describe secretion in urine production?

A
  • Similar to reabsorption, but in reverse
  • Molecules removed from blood and transported into the filtrate
  • Molecules secreted include: K+, H+, NH3, urea, creatinine, histamine and drugs like penicillin
33
Q

Name the 4 regions of the renal tubule and their function.

A
  1. Proximal tubule
    Reabsorbs ions, water, and nutrients from the filtrate into the interstitial fluid, and actively transports toxins and drugs from the interstitial fluid into the filtrate.
  2. Loop of Henle
    H2O, Na+ and Cl– ions diffuse and transport into the interstitial fluid.
  3. Distal tubule
    K+ and H+ ions are selectively secreted into the filtrate, while Na+, Cl–, and HCO3– ions are reabsorbed to maintain pH and electrolyte balance in the blood
  4. Collecting duct
    Reabsorbs solutes and water from the filtrate, forming dilute urine
34
Q

How are ions transported in tubule regions?

A

Differences in transport and permeability due to differences in epithelium along the tubule

35
Q

How are ions transported in proximal tubule regions?

A

Most reabsorption of solutes and water takes place in proximal tubule

Proximal tubule also carries out secretion

36
Q

How is glucose reabsorbed?

A

Glucose is reabsorbed by secondary active transport

Reabsorbed molecules taken up by the blood

37
Q

How are ions and water transported in the loop of henle?

A

Descending limb is permeable to water

Ascending limb is impermeable to water

Reabsorbed ions accumulate in interstitial fluid in ascending limb

38
Q

How are ions and water transported in the distal tubule?

A

Distal tubule can reabsorb salts and water

Transport function of distal tubule affected by hormones

39
Q

How does the loop of Henle acts as a countercurrent multiplier?

A
  • Creates an osmotic gradient that facilitates reabsorption of water in collecting duct
  • Decending limb pumps out water as ascending limb pumps out ions.
  • Concentration of ions increases in decending limb and moves to ascending limb which allows for more ion pumping
  • Low osmolarity near cortex
  • High osmolarity deep in medulla
  • Collecting duct is permeable to urea in medulla
  • *Increases local osmolarity
40
Q

Describe excretion in urine production?

A

After urine is produced, it leaves kidney and enters the urinary bladder via ureters

Urine leaves bladder via urethra

41
Q

How is urinary function regulated?

A

Hormones affect kidney function: Steroid hormones and Peptide hormones

Dietary factors that affect urine output: Caffeine, water, alcohol

42
Q

Whats Antidiuretic hormone (ADH)?

A
  • Produced in hypothalamus, released by posterior pituitary gland
  • Increases water reabsorption from the collecting duct by increasing the number of aquaporins
43
Q

What increases cell permeability? How?

A

Vasopressin.

  1. Vasopressin binds to G protein receptor
  2. Receptor activates adenylate cyclase, increasing cAMP and activating protein kinase A
  3. Phosphorylation of exoskeleton and protein vesicles
  4. Translocation of vesicle to cell mb with insertion of aquaporins
44
Q

Whats aldosterone? Function?

A
  • Produced by adrenal gland in tetrapods
  • Stimulates Na+ reabsorption
    1. Aldosterone enters cell by diffusion
    2. Binds to receptor
    3. Transcription of genes for transporters
    4. New transporter proteins made in ER and exported in vesicles
    5. Vesicles containing proteins sent to PM
45
Q

How do sponges excrete waste?

A

Waste products are expelled through the osculum by the current created by the choanocytes to pull water into the sponge

46
Q

How do flatworms excrete waste?

A

Protonephridia
At the end of each tubule of the nephridium is a ciliated flame cell.
…As fluid passes down the tubule, solutes are reabsorbed and returned to the body fluids. … Water is reabsorbed and waste is expelled from the insect

47
Q

How do mollucs and annelids excrete waste?

A

Metanephridia
Body fluid is drawn in from the nephrostome, substances are filtered, selected or reabsorbed as necessary. The wastes are excreted from the nephridiopore

48
Q

How do insects excrete waste?

A

Malpighian tubules
Branching tubules extending from the alimentary canal that absorbs solutes, water, and wastes from the surrounding hemolymph.

49
Q

Do fish have a loop of henle? How do they excrete their waste?

A
  • No.

- Have large nephron

50
Q

Why was the loop of henle a major innovation?

A

Allows production of concentrated urine

51
Q

Are loops in beavers, kangaroos, rabbit long or short?

A

Beaver- short
Kangaroos- long
Rabbit- Both