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Animal Physiology > 1-6: Intro, Osmoregulation > Flashcards

1-6: Intro, Osmoregulation Flashcards

(123 cards)

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1
Q

What does surface tension do?

A

Keeps water out of where we don’t want it

Eg. breathing tubes in insects

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2
Q

How much of an animal’s body mass does water make up?

A

60-90%

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3
Q

What fluid compartments is water divided into?

A 
Intracellular fluid (ICF)
Extracellular fluid (ECF)
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4
Q

Is there more ECF or ICF in soft-bodied invertebrates?

A

ECF

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5
Q

What is ECF in vertebrates split into?

A

Plasma

Interstitial fluid

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6
Q

What is homeostasis?

A

The maintenance of a constant internal environment

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7
Q

What is the ICF high in?

A

K+, phosphates, proteins

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8
Q

What is the ECF high in?

A

Na+, Cl-

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9
Q

How does the ICF make up for the lack of Na+?

A

High K+

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10
Q

Active transporters

A

Pumps

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11
Q

Passive transporters

A

Channels

Carriers

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12
Q

3 types of carrier-mediated transport

A

Facilitated diffusion- uniport
Cotransport- symport
Countertransport- antiport

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13
Q

Why are most animal cells more negative inside compared to outside?

A

Due to an asymmetric distribution of K+

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14
Q

How is K+ maintained?

A

Na+K+ ATPase

The membrane is more permeable to K+ than other ions

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15
Q

What is the resting membrane potential?

A

-60mv

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16
Q

How is water transported across cell membranes?

A

Aquaporins

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17
Q

What are aquaporins?

A

6 membrane-spanning domain
Single polypeptide chains
13 types in mammals

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18
Q

What are aquaglyceroporins?

A

Also permeable to glycerol

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19
Q

What is osmosis?

A

The diffusion of water through a semi-permeable membrane from a region of lower total solute concentration to one of a higher total solute concentration

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20
Q

What is osmolarity?

A

The concentration of a solution expressed as the total number of solute particles per litre

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21
Q

What does the rate of osmosis depend on?

A

The osmotic permeability of the membrane

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22
Q

What is the total solute concentration?

A

The total of all the solute present

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23
Q

What is molarity?

A

The concentration in moles per litre (M)

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24
Q

What osmolarity do ICF and ECF have?

A

The same- equal osmolarity

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25
What does isotonic mean?
Equal osmolarity
26
What does hypertonic mean?
Higher osmolarity
27
What does hypotonic mean?
Lower osmolarity
28
ECF composition in marine vertebrates
ECF is similar to water | Lower Na+ and Cl- due to evolutionary origin in freshwater
29
Teleost ECF
Hypotonic
30
Elasmobranch ECF
Isotonic
31
ECF composition in freshwater/terrestrial
ECF is like diluted seawater
32
What are osmoconformers?
Marine organisms that maintain an internal environment that is osmotic to their external environment Osmolarity of cell's is equal to osmolarity of surrounding environment
33
What are ionoconformers?
Same ion concentrations of ECF as the outer environment
34
What are osmoregulators?
ECF is kept different from environmental values
35
What is the best way to maintain constant ECF composition?
Seal off from the outside world
36
Unavoidable areas of uptake/loss of ions
Skin Respiratory surfaces Digestive tract Excretory organs
37
2 distinct surfaces of a membrane
Apical (eg. facing gut lumen) | Basolateral (eg. ECF)
38
How are epithelia connected?
Tight junctions
39
Examples of epithelia involved in osmoregulation
``` Kidneys Urinary bladder Malpighian tubes Gills Skin Rectal glands Nasal salt glands ```
40
Features of sea water
``` Rich in NaCl Osmolarity 1000-1150mOsm Low in K High in Mg and sulphate Constant salinity at depth ```
41
Marine invertebrate ECF (compared to outside)
Isosmotic | Some ionoregulation- high K+ in squid for nerve conduction, reduced SO42- in pelagic species for buoyancy
42
Marine invertebrate ICF
Isosmotic with sea water | Ionic balance is different
43
Marine vertebrate groups
1- ECF roughly isosmotic to sea water- eg. hagfish, elasmobranchs 2- ECF osmolarity roughly a third of sea water- eg. lampreys, teleosts
44
Hagfish ECF
Na+ and Cl- concentration similar to seawater Osmoconform Ionoconform More like marine invertebrates Stenohaline (intolerant of brackish/dilute water)
45
Lamprey ECF
Na+ and Cl- in ECF 1/3rd of seawater Euryhaline- tolerate a range of osmolarity Migrate into freshwater
46
How do elasmobranchs make up osmotic deficit?
Urea and TMAO
47
What is urea?
End product of protein metabolism Actively reabsorbed in kidney Kidney holds onto urea
48
What is TMAO?
Another protein metabolite | Balances destabilising effect of urea on proteins
49
Osmoregulation in elasmobranchs- parts of body
``` Digestive tract- salt uptake Kidney- retains urea and TMAO Gills- loss of urea and salts, water uptake Urine- salt lost Rectal gland- excretes excess salt ```
50
What is the elasmobranch rectal gland?
Cylindrical organ with central lumen, drains into rectum
51
How does the rectal gland work?
Cl- accumulated in cell Cl- efflux into the tubule lumen by secondary active transport Secretion of isotonic NaCl Na+ flux through tight junctions into tubule lumen
52
Other examples of ureo-osmoconformers
Chimaeras | Coelacanths
53
Teleost ECF
Hypoosmotic- 1/3 of sea water | No urea or other ECF osmolyte to make up the difference
54
Problems with teleost ECF
Loss of water by osmosis (by gills) | Gain of salt (by digestive tract)
55
To solve teleost ECF problems
Drink sea water to replace lost water Produce minimal urine Excrete excess salt via gills
56
Teleost parts of body
Gills- actively excrete salt, lose water Mouth- gain water and salt from drinking sea water Urine- small volume of isosmotic urine produced
57
Teleost kidney features
No loop of Henle Can't concentrate urine Rich in divalent ions
58
Chloride cells in teleosts
Large epithelial cells at the base of secondary lamellae Packed with mitochondria Lots of folding of basolateral membrane For salt transport- same mechanism as elasmobranch rectal glands Secondary active transport of Cl- across basolateral membrane Paracellular diffusion of Na+ driven by electric potential gradient
59
What volume of all water on earth is freshwater?
0.01%
60
What can freshwater be composed of?
Salts from rainwater, picked up from dust as it falls | Minerals picked up from rocks- few from granite, lots from limestone
61
What is the normal freshwater salt concentration?
0.1-10mM
62
What type of water contains more ions?
Hard water
63
Fresh water ICF
All maintain above the fresh water value Some higher than others K+ dominant
64
What do you not find in freshwater?
Echinoderms | Cephalopods
65
Freshwater ECF composition
Na+ and Cl- dominate | Some K+ and divalent ions
66
Freshwater problems
Gain water by osmosis | Lose solutes by diffusion and excretion
67
Freshwater solutions
Minimise permeable surfaces- but need for gas exchange Produce hyposmotic urine- lose lots of water, little salts Actively take up salts from environment- via gills and skin
68
How do freshwater animals lower water permeability of external surfaces?
Have hard surfaces | Eg. crabs
69
What are flame cells?
In freshwater flatworms, rotifers and nemerteans Produce primitive urine Found all over body
70
How do flame cells work?
Have a flagellum that propels fluid down the duct Cilia draws ECF through gaps between cells Negative hydrostatic pressure sucks water in Reabsorption of ions by tubule cell
71
What are flame cells grouped as?
Primitive 'kidneys' | Called protonephridia
72
What are metanephridia?
Excretory glands found in many types of invertebrates | Eg. annelids, arthropods, mollusca
73
What are coelomoducts?
Excretory gland and genital ducts Wide and ciliated lumen opening into a coelom Terminate externally by a small pore in the body wall
74
What is the crayfish antennal gland?
The 'green gland' Ultrafiltrates haemolymph into a coelomosac Reabsorption of ions in the labyrinth and canal Minimal water reabsorption
75
Basic principles of urine production
Energetically expensive due to reabsorption But safe for excreting toxins Excrete everything, reabsorb what you want to keep
76
Fresh water elasmobranch features
A few marine species enter rivers successfully, some are exclusively fresh-water Eg. Amazon stingray, Lake Nicaragua shark (bulls) ECF similar to humans, very different from marine sharks ECF doesn't contain urea or TMAO
77
Freshwater teleost features
``` ECF around 300mOsm Gain salt and water from feeding Gain water from gills and body surface Actively uptake salt via the gills Excrete large amounts of hyposmotic urine- loss of salt ```
78
Freshwater teleost kidneys
Higher filtration rate than sea water species Similar proximal tubule function to sea water- reabsorption of vital solutes Different distal tubule and collecting duct- NaCl reabsorption, low water permeability
79
Freshwater teleost gills
NaCl uptake is coupled with CO2 excretion Want to absorb as much salt as possible Use 2 pumps- NaCl pump and proton pump at apical side
80
What are catadromous fish?
Spawn in the sea Young migrate up rivers for most of their life Return to sea to spawn Eg. freshwater eels
81
What are anadromous fish?
Spawn in rivers Young migrate to sea to grow Return to rivers to spawn Eg. atlantic salmon
82
How do fish go from freshwater to seawater?
H+ATPase is downregulated NaCl uptake is supressed Increased plasma Na+ = hormone secretion Hormones stimulate chloride cell proliferation Increase in Na+K+ATPase activity, secretion of NaCl Plasma Na+ levels are restored =GILLS
83
How do fish go from seawater to freshwater?
``` Low Na+ closes tight junctions NaCl excretion stops Plasma prolactin levels rise, which reduce no. of chloride cells Na+K+ATPase activity falls Up-regulation of H+ATPase NaCl uptake restored =GILLS ```
84
2 evolutionary routes onto land
From sea water via the littoral zone- tolerate desiccation and osmotic variations From fresh water via swamps and bogs- produce hyposmotic urine
85
What are the most successful phyla and what routes did they take?
Arthropods- both routes | Vertebrates- mainly freshwater
86
What are interstitial fauna?
Small soil organisms surrounded by water film Virtually aquatic Eg. rotifers, nematodes
87
What are cryptozoic fauna?
Hiding animals- larger soil organisms High humidity Eg. worms, centipedes
88
What are hygrophilic fauna?
Wet-loving, moist-skinned Require humidity Limited tolerance of desiccation Eg. slugs, snails, amphibians
89
What are xerophilic fauna?
Dry-loving Free-living above ground Eg. insects, mammals, birds
90
ECF composition of land animals
``` 200-500mOsm Lower in ex-fresh than ex-marine Dominance of Na+ and Cl- High Ca2+ in some inverts Vertebrates have ECF osmolarity of around 300, similar to freshwater fish ```
91
What is the main form of water loss?
Evaporation | Called evaporative water loss (EWL)
92
2 ways that water can be lost
Cutaneous- by skin | Respiratory- by the linings of airways, alveoli
93
How is water loss increased?
High temperatures | Low humidity and airflow
94
Behavioural adaptations to prevent water loss
Seek dark, damp, cool places
95
How is cutaneous water permeablility reduced?
Dense cuticles (arthropods) Keratinised layers of dead skin cells (tetrapods) Lipid content
96
How is water aquired?
Drinking-streams, dew Diet- wet or hygroscopic foods, eg. seeds Osmosis via other organs- abdominal skin in amphibia Dew capture- dawn frogs in coastal deserts, condensation drains to the head Metabolic water- from oxidative metabolism
97
How is drinking controlled?
Increased ECF osmolarity detected by osmoreceptors, goes to hypothalamic thirst centre Decreased ECF volume detected by volume receptors, activates renin-angiotensin system, goes to hypothalamic thirst centre
98
What are kidneys/variations of kidneys for?
The excretion of waste products Require a modest output of water Main site for regulating water content and ion balance
99
Nephridia in flatworms and nemerteans
Flame cells organised into protonephridia | Slighly hyposmotic urine
100
Nephridia in annelid worms
Segmental nephridia Hyposmotic urine Each segment has its own 'kidney'
101
Nephridia in slugs and snails
Ultrafiltration from the pericardium Hyposmotic urine with water is plentiful Solid paste when water is short Can't produce hyperosmotic urine
102
Malpighian tubes in xerophilic arthropods
Produce isosmotic fluid by active secretion from haemolymph Drains into midgut Active reabsorption of hyposmotic fluid in rectum
103
What are malphighian tubules?
Have cation pumps at the apical membrane Cation is K+ in herbivores, Na+ in blood feeders Cl- moves passively via stellate cells High water permeability
104
What is the cryptonephridial system?
``` In some beetles and lepidopteran larvae Malpighian tubes lie close to rectum Have an impermeable perinephric membrane Also counter current system Produce hyperosmotic excreta (up to 5000mOsm) ```
105
Amphibia urine
Freshwater-adapted kidney Hyposmotic urine Salt uptake via skin
106
Reptile urine
Isosmotic urine | Salt excretion via salt glands
107
Bird urine
Normally hyposmotic urine Some have salt glands Some have loop of Henle
108
Mammals
Most have loop of Henle | Hypo or hyperosmotic according to need
109
What are salt glands?
Important in birds/reptiles living close to sea Secrete hypertonic NaCl Can be in eye sockets, nasal cavity, mouth, top of skull Similar mechanism to rectal glands and chloride cells
110
Main principle of the mammalian kidney
Ultrafiltration | Selective reabsorption/secretion
111
What does too little sodium cause?
Collapse in the circulatory system
112
How is the kidney able to produce hyperosmotic urine?
Due to the loop of Henle
113
What cannot pass through into the filtrate?
Blood cells | Proteins
114
What is the filter in the glomerulus
Basement membrane of the capillary endothelium
115
What happens in the proximal convoluted tubule?
Isosmotic reabsorption of 75% of NaCl and water | Concentration of waste products eg. urea
116
What happens in the descending limb of the loop of Henle?
Passive reabsorption of water
117
What happens in the thick ascending limb of the loop of Henle?
Active reabsorption of NaCl
118
What happens in the distal convoluted tubule?
Aldosterone-regulated reabsorption of Na+
119
What happens in the collecting duct?
ADH-regulated reabsorption of water
120
How does the loop of Henle create a hyperosmotic ECF in the inner medulla?
Osmotic water efflux from descending limb Passive salt efflux from thin ascending limb Active salt transport out of thick ascending limb
121
What does ADH do?
Causes an organism to retain water
122
Kangaroo rat water
Survive without drinking Produce small volumes of very hyperosmotic urine Water gained from metabolism Unavoidable loss by evaporation
123
Marine mammal water
``` Whales, porpoises etc Drink little sea water Water intake is mainly from diet Do not have salt glands Hyperosmotic urine ```

Animal Physiology (3 decks)

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