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BIO311D: Biology > OSMOREGULATION AND EXCRETION > Flashcards

OSMOREGULATION AND EXCRETION Flashcards

1
Q

What is a portal system?

A

A portal system is a vascular system that begins and ends at a capillary bed with no pumping mechanism in between

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2
Q

What are the 3 types of portal systems in the human body?

A
  1. Hypothalamohypophyseal portal
  2. Renal portal
  3. Hepatic portal
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3
Q

How does the hepatic portal system function?

A

Blood which enters through the hepatic portal vein from the intestine is rich with nutrients but also toxins

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4
Q

What is osmoregulation?

A

Osmoregulation is required by homeostasis and is the general term for the process by which organism control solute concentrations and balance water gain and loss

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5
Q

What is excretion?

A

Excretion is the ridding of nitrogenous waste and other metabolic waste products from the body

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6
Q

How does water leave and enter cells?

A

Through osmosis, which occurs when 2 solutions separated by a membrane differ in total solute concentrations

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7
Q

What is osmolarity?

A

Osmolarity is the unit of measurement for the solute concentration and is represented by the number of moles of solute per liter of solution (e.g. 300 mOsm/L human blood)

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8
Q

What is the formula for osmolarity?

A

Osmolarity = molarity (moles/L) x # particles/molecule

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9
Q

What is an isoosmotic solution?

A

An isoosmotic solution is when 2 solutions of the same osmolarity continuously share water molecules at equal rates in both directions across a semipermeable membrane

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10
Q

What is a hyperosmotic solution?

A

A hyperosmotic solution is the solution with the higher concentration?

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11
Q

What is a hypoosmotic solution?

A

A hypoosmotic solution is the more diluted solution, or rather the solution with the lower concentration of solutes

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12
Q

What direction do water molecules move?

A

Water molecules move from the less concentrated solution to the higher concentrated solution, reducing the concentration difference for both solutes and free water via dilution

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13
Q

What are the 2 ways in which animals can maintain water balance?

A
  1. Osmoconformer
  2. Osmoregulator
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14
Q

What is an osmoconformer?

A

An osmoconformer is an organism which is isoosmotic with their surroundings, meaning their internal osmolarity is stable and the same as that of the environment, so there is no gain or loss of water

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15
Q

What is an osmoregulator?

A

An osmoregulator is an organism whose control of internal osmolarity is independent of that of the external environment

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16
Q

Why do osoregulators expend more energy then osmoconformers?

A

Osmoregulators must expend energy to maintain the osmotic gradients that cause water to move in and out, which is done through the active transport of solutes

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17
Q

How do animals control solute concentrations?

A

Animals can indirectly control solute concentrations in cells by managing solute content of an internal body fluid that bathes the cells

Transport epithelia are also required, which are 1+ layers of epithelial cells specialized in moving regulating solute movement

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18
Q

What are waste products composed of?

A

Nitrogenous breakdown products of proteins and nucleic acids, which are broken down for energy or converted into carbohydrates and fats while enyzmes remove nitrogen in the form of ammonia, which is very toxic

19
Q

What are the different forms of nitrogenous waste?

A
  1. Ammonia - toxic, but aquatic organisms dilute their waste with water; lowest energy cost
  2. Urea - much less toxic, requiring less water for dilution; requires more energy to convert ammonia to urea
  3. Uric acid - least toxis, requiring least water for dilution; required the most energy to produce
20
Q

What are the key functions of every excretory system?

A
  1. Filtration
  2. Reabsorption
  3. Secretion
  4. Excretion
21
Q

What is filtration?

A

Filtration is the filtering of body fluids producing filtrate, which is then collected in the excretory tubes

22
Q

What is reabsorption?

A

Reabsorption is the reclaiming of valuable substances from the filtrate by the transport epithelium, and returning them to body fluids

23
Q

What is secretion?

A

Secretion is the addition of toxins and other solutes from body fluid to filtrate

24
Q

What is the principle site of osmoregulation?

A

The kidneys

25
Q

What is the name of the duct in which urine leaves the kidneys?

A

Ureter

26
Q

What is the name of the duct in which urine leaves the bladder?

A

Urethra

27
Q

What is the first collection point of urine in the kidneys?

A

Renal pelvis

28
Q

A closer look at what happens in the proximal tubule:

A
  1. Reabsorption is critical for the recapture of ions, water, and valuable nutrients from the huge volume of initial filtrate
    1. NaCl enters by facilitated diffusion and is then moved to interstitial fluid by active transport
    2. H2O reduces filtrate volume
    3. Glucose, amino acids, K+ and other essentials are transported from filtrate to intertitial fluid
  2. Filtrate processsing helps maintain pH
    1. H+ is secreted into lumen
    2. 90% of the buffer HCO3- is reabsorbed from filtrate
  3. As filtrate passes, materials to be excreted become concentrated
29
Q

A closer look at what happens in the descending limb of the Loop of Henle:

A
  1. Filtrate volume is further reduced
  2. Aquaporins allow permeability to water, resulting in an increase in solute concentration
  3. No channels for salts or other solutes
30
Q

A closer look at what happens in the ascending limb of the Loop of Henle?

A
  1. Lacks water channels and is therefore impermeable to water, diluting filtrate as it moves up the cortex
  2. Thin region near loop allows NaCl diffusion into interstitial fluid to help maintain osmolarity
  3. Thick region adjecent to the distal tubule allows the active transport of NaCl
31
Q

A closer look at what happens in the distal tubule:

A
  1. Key to regulating K+ and NaCl concentrations
    1. K+ secreted into filtrate
    2. NaCl reabsorbed from filtrate
  2. pH regulated by controlling H+ secretion and HCO3- reabsorption
32
Q

A closer look at what happens in the collecting duct:

A
  1. Filtrate processed into urine
  2. Hormone control of permability and transport determine extent to which urine becomes concentrated
  3. Impermeable to salts and, in the renal cortex, urea
33
Q

If ATP production stopped, urine production would…?

A

Decrease and be isoosmotic to plasma

34
Q

What is the primary solute affecting osmolarity?

A

NaCl

35
Q

Why is the production of urine hyperosmotic?

A

Because considerable energy is expended for active transport of solutes against concentration gradients

36
Q

What is the function of the anti-diuretic hormone (ADH)?

A

ADH restores normal osmolarity by increasing permeability to water when there is an increase in blood osmolarity

37
Q

What released ADH?

A

ADH is produce by the hypothalamus and “stored” in the posterior pituitary gland

38
Q

What is the function of the renin-angiotensin-aldosterone-system (RAS)?

A

RAAS increases blood pressure and regulates kidney functions when the body needs to reduce blood volume without increasing osmolarity?

39
Q

What is the function of the JGA in RAAS?

A

The JGA releases renin when blood volume or pressure drops, allowing for the cleavage of angiotensin into angiotensin II

40
Q

What is the function of angiotensin II in RAAS?

A

Angiotensin II triggers vasocontriction, increasing blood presure and decreasing blood flow

41
Q

What stimulates the release of aldosterone from the adrenal glands?

A

Angiotensin II

42
Q

What is the fuction of aldosterone in RAAS?

A

Aldosterone causes nephron’s distal tubules and collecting ducts to reabsorb Na+ and water

43
Q

What is the function of the atrial natriretic peptide (ANP)?

A

ANP opposes RAAAS and decreases blood pressure or volume through 1 of 3 ways:

  1. Inhibiting the release of renin from the JGA
  2. Ihibiting reabsorption of NaCl
  3. Reducing release of aldosterone

BIO311D: Biology (14 decks)

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