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Topic 9: control systems > 9.9 osmoregulation and temperature regulation > Flashcards

9.9 osmoregulation and temperature regulation Flashcards

1
Q

what is deamination?

A

the removal of the amino group from excess amino acids that is converted into ammonia and then urine

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2
Q

where does deamination take place?

A

in the liver

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3
Q

why can we not store ammonia?

A

very toxic and highly soluble

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4
Q

what are the two main functons of the osmoregulatory role of the kidney?

A
  • ultrafiltration
    -selective reabsorption
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5
Q

what are the tubules in kidneys called?

A

nephrons

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6
Q

where does ultrafiltration take place?

A

glomerous and Bowman’s capsule

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7
Q

how is high pressure created in the glomerous?

A

same volume of blood passes through the afferent and efferent arterioles that have different size lumens

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8
Q

what happens during ultrafiltration?

A

1- under high pressure, plasma and much od it’s content is forced out of the endothelium of the glomerous
2- it passes through a basement membrane which filters out molecules based on size and charge
3- basement membrane is made of collagen and glycoproteins

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9
Q

what are podocytes?

A

specialised cells of the Bowman’s capsule that have projections that wrap around the glomerolous, between projections are filtrations slits which allow more filtrate to pass

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10
Q

what three layers does the filtrate have to pass through to get to the nephron?

A
  • endothemium of the glomerous
  • basement membrane (filter)
  • the epithelium of the podocyte
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11
Q

what does the filtrate contain?

A
  • water
  • salts (Na,Cl,K)
  • small amino acids
  • glucose
  • urea
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12
Q

what does not pass into the filtrate?

A
  • blood cells
  • large plamsa proteins
  • polypeptides
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13
Q

what does the proximal convulated tubule selectively reabsorb?

A
  • most of the water
  • some of the salts
  • all the glucose and amino acids
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14
Q

what are the adaptations of the proximalk convulated tubule?

A

-thin walls
- microvilli
- abundance of mitochondria
- tight junctions

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15
Q

how does selective reabsorbtion in the proximal convulated tubule happen?

A

1- sodium-potassium pumps in the basal membrane moves sodium ions out of the epithelial cells and into the blood
2- this lowers sodium concentration in epithelial cells, causing others in the filtrate to difuse down the concentration gradient through co-transporter proteins
3- these proteins transport a sodium ion and another solute (glucose or amino acid) this is secondary active transport
3- water moves by osmosis from the filtrate to the blood due to lower water potential
5- a few proteins are taken back into the blood by pinocytosis

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16
Q

what occurs in the loop of Henle?

A

osmoregulation

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17
Q

what does the loop of Henle create?

A

a counter current multiplier

18
Q

what happens in the descending limb?

A
  • filtrate flows into descending limb and as it enters the medulla the surrounding fluid becomes increasingly concentrated
  • this causes water to passively diffuse out into the vasa recta that is permeable to water but not salts
19
Q

what happens in the ascending limb?

A
  • filtrate then enters the ascending limb which is impermable to water but actively transports sodium chloride out of the tubule and into the fluid
  • as salts are pumped out the concentration in the ascending limb decreases because water is unable to flow
  • this draws out water from the descending limb
20
Q

what is the role of the distil convulated tubule?

A

pH regulation

21
Q

what are the features of the distil convulated tubule?

A
  • back in cortex
  • measure blood pH
  • blood proteins help to maintain pH as they are buffers
  • movement of H+, OH- ( hydroxide ions) and HCO3 (hydrogen carbonate ions) maintain pH
  • reabsorbtion of some ions leaves urine acidic or alkali
22
Q

what happens in the collecting duct?

A
  • permeability of walls of the collecting duct is determined by presence of ADH
  • high ADH causes walls to be fully permeable to water
  • water will leave collecting duct by osmosis due to the presence of Na+ and Cl- in the medulla
23
Q

how are kangeroo rats adapted to live in dry climates?

A
  • they have long loops of Henle which builds a higher ion concentration in the medulla as the longer the loop, the more water will be reabsorbed in the collecting duct
  • higher number of infoldings in the cell membranes of the epithelial cells ligning the tubules, which give increased surface area for diffusion of inorganic ions and water, making steep concentration gradients possible
  • high number of mitochondria found in the epithelial cells of the nephrons, providing energy for the active pumping of inorganic ions into or out of the tubules
24
Q

where is ADH produced?

A

hypothalamus and stored in the pituitary gland

25
Q

what does ADH do?

A

increases the permeability of the distal convulated tubule and the collecting duct to water

26
Q

when is ADH released?

A

when water potential of the blood is low

27
Q

what type of molecule is ADH?

A

protein (so binds to receptors on the outer membrane)

28
Q

how does ADH work?

A

1- binds to receptors on outer membrane
2- ADH acts as a first messenger that initiates cAMP which activates the enzyme phosphorylase
3- this causes aquaporins to move to the membrane and fuse making water channels available
4- therefore the permeability of these membranes increase

29
Q

what are aquaporins?

A
  • small vesicle that has intergal protein channels in it’s membrane to allow the passage of water molecules out of the cell
  • when these are required they can bind with the cell membrane and present their water channels, therefore increasing the amount of water that can pass through
30
Q

how do organisms warm up?

A

as a by-product of metabolism because chemical inefficiency means energy is wasted which warms the core of the organism

31
Q

how do organisms cool down?

A

by evaporation of water from the body surfacesw

32
Q

what are the two classifications of methods of temperature control?

A
  • endotherms
  • ectotherms
33
Q

what is an endothem?

A

a mammal that relies on it’s own metabolic processes to provide at least some warming and usually has a higher body temperature than the ambient temperature

34
Q

what is an ectotherm?

A

mammals that rely heavily on the external environment to control their body temperature

35
Q

how do ectotherms keep themselves warm or cool down?

A
  • they warm up by basking in the sun or pressing themselves to warm surfaces
  • to cool down they may move into the shade or into mud and water
36
Q

what is the major homeostatic organ involved in thermoregulation?

A

the skin

36
Q

how does the skin keep up cool?

A
  • closes shunt which allows vasodialation and loss of heat by convection, radiation and conduction
  • erector muscle relax and body hairs lie flat on skin, minimising any insultion
  • sweat production in sweat glands increases as when it evaporates it has a cooling effect
36
Q

how does the skin keep us warm?

A
  • shunt opens allowing vasoconstriction to avoid loosing heat by conduction, convection and radiation
  • sweat production is reduced
  • erector muscles contract leaving hairs standing on ends to create an insulating layer
  • shivering helpos increase metabolic warming
36
Q

what are the two types of receptors that handle thermoregulation?

A
  • receptors in the brain (directly moniter temperature of the blood)
  • receptors in the skin (detect changes in the external environment)
37
Q

what happens when the temperature of the blood flowing through the hypothalamus rises?

A

thermoregulatory centre is activated and sends out an impulse along the autonomic motor nerves to effectors that increase the blood flow through the skin and increase sweating

37
Q

where are the temperature receptors in the brain?

A

hypothalamus

38
Q

how do some endotherms survive cold climates?

A

hibernation

Topic 9: control systems (9 decks)

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