Lecture 5 & 6 Flashcards

1
Q

Define Homeostasis ?

A

is the maintenance of a stable internal environment for the preservation of the normal functioning of cells.
eg.) body temp etc

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2
Q

What are cells surrounded by ?

A

Surrounded by ECF
1.) Ionic comnposition
2.)Solute concentration of ECF
3.)Health of cells is critical for normal function
Homeostasis of the ECF is the job of excretatory system

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3
Q

Define the chemical composition of the body ?

A

Body water -60% total body weight

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4
Q

Define body water divsions ?

A

Body water contains many dissolved ions/substances in solution called fluid
-ECF
subdivided into the plasma and interstitial fluid
-ICF
Hydrates interstitial space /Intertitium

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5
Q

How do species maintains maintains homeostasis of its ECF ?

A

Its environment :salt/fresh water,terrestrial
Its lifestyle

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6
Q

What do animals depend on to maintain ?

A

Depnd on excretory system
-volume,concentration and composition of their ECF and to excrete wastes eg.)urine
-Such systems use filtration ,secretion,and reabsorption to regulate
1.)Osmolarity
2.)Ionic composition of ECF

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7
Q

Define Osmosis ?

A

Water moves from a region of high water concentration to one of lower water concentration
-in order to maintain a homeostatic balance
1.) Remove excess fluid and retain specific ions or solutes.
2.) Conserve fluids and excrete excess ions or solutes
3.) Excrete waste products of nitrogen metabolism output:urine

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8
Q

What does osmosis require ?

A

1.)A semi-permeable membrane permitting water ,but not solute movement
2.)A difference in the solute concentration ( on either side)
In all animal excretory system there is no active system

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9
Q

Can water molecules diffuse across cell menbranes ?

A

yes despite being a polar molecule
slow process most passes through aquaporins

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10
Q

What are water channels ?

A

aqua porins
possess pores allowing water to pass from one side of the membrane to the other
found in tissues which transport large volumes of water per day
eg.) tubules of the kidney

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11
Q

What is osmotic pressure ?

A

amount of pressure that needs to be applied to just stop this movement
Solutes will displace water
lowering the water concentration

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12
Q

How does water move ?

A

water moves from the solution with a lower osmotic pressure into thr solution with higher osmotic pressure

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13
Q

Define Molarity ?

A

concentration of a substance expressed in moles per litre of that solution

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14
Q

Whta is Vant Hoffs law ?

A

is dependent on the toal number of dissolved particles present in solution which is measured in osmoles

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15
Q

Define Osmolarity ?

A

the meaure of solute concentration defined as the no of osmoles per litre of solution

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16
Q

Define Osmolality ?

A

number of osmoles per kg of solution

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17
Q

Define hyposmotic ?

A

low osmotic pressure

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18
Q

Define isotmotic ?

A

One that has the same osmotic pressure as that of the cells
Solutions isomotic to cells are not always isotonic in the long run;osmolarity and tonicity are related

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19
Q

Define hypotonic solution ?

A

has an osmotic pressure less than that of cells
cells will shrink becuase of osmotic water loss

20
Q

Hyoertonic solution ?

A

has greater osmotic pressure than that of cells ;cells will shrink becuase of osmotic water loss

21
Q

What is tonicity ?

A

is a measure of osmolarity or osmolality on cell volume

22
Q

Define Stenohaline ?

A

species that can tolerate only a narrow range of environmental/ambient salinity (conc of salt in seawater)
Mosy open ocean invertebra are ONSCOFORMERS
(rarely experience dilute seawater )

23
Q

Define Euryhaline ?

A

Species especially estuarine species (brine shrimp)
can survuve wide range of salinity
-likely osmoregulators

24
Q

What are humans ?

A

Osmoregulators

25
Q

Whats the difference between osmoconformers and osmoregulators ?

A

Aquatic animals either conform to osmolarity (of environment ) or they expand (metabolic energy) to maintain constant internal osmolarity
-most marine invertebraes are osmoconformers
-osmolarity of ECF is in eqm with external envirnment
advantage-saves energy
other aqautic animals -osmoregulators
-maintain constant internal osmolarity

26
Q

what are freshwater teleoast fish ?

A

freshwater bony fish :(

27
Q

In Freshwater bony fish what is their blood?

A

Blood is hyperosmotic compared to the environment
Salts must be retained and excess water excreted
Water uptake by osmosis

28
Q

Marine seawater teleost fish ?

A

hypoosmotic to the water they live in
blood is hypoosmotic compared with the environment
water must be retained and excess salts excreted

29
Q

How does ion uptake occur in freshwater fish ?

A

Active ion uptake in the gill epithelium
freshwater animals lose ions in their pee
also through direct outward diffusion across gills
IONS NEED TO BE REPLACED

30
Q

Are all aquatic vertebrates osmoregulators ?

A

almost
NOT SHARKS,FISH,RAYS AND HAGFISH

31
Q

What happens n=in idlute water with freshwater fish ?

A

Take on water ata an accelerated rate by OSMOSIS
water influx into ECF :
↓ osmotic pressure of blood
↓ blood ion conc
expands blood vol (cells may swell)

32
Q

How do animals resoond to changes above?

A

negative feedback
Kidneys,(gills,salt glands) can reverse changes in blood composition
-Regulate composition -removing h2o,salt,aminoacids from plasma in controlled way

33
Q

What is water conversation & what is it dependant on ?

A

essential-water balance
Need to eliminate salt/conserve dependant on animals diet
Herbivores -Tend to conserve salt
Marine birds-ted to eliminate
(also ahve salt glands

34
Q

What do some birds have ?

A

nasal salt glands
as not sufficient to maintain blood hyposmotic to seawater

35
Q

Where are the salt glands located ?

A

in depressions in skull above eyes
bundles of secretory tubules served by parrallel arrangements of arterioles & venules
tubules→drain into central canal→into nasal cavity

36
Q

How do nasal cavities work ?

A

Cl- actively transported into tubule cells from ECF
When Cl- channels on tubule side of cell membrane open,
Cl- diffuses into tubule & Na + follows .
H2O drawn into tubule by osmosis & flushes the NaCl solution into central canal
excess salt is excreted -2° active transport of Cl

37
Q

What do animal excretory systems use ?

A

Filtration
Secretion
Reabsorption
To regulate osmolarity & composition of ECF

38
Q

What loosley takes place in Filtration ?

A

water & small molecules are filtered & collected in a tubule
Driven by blood pressure

39
Q

What loosley takes place in Secretion & Reabsorption ?

A

Active processes (i.e-need ATP) that alter the filtrate composition in tubule

40
Q

The excretion of nitrogenous waste ?

A

Ammonatellic animals (fishy)-Ammonia
Ureotelic (mamals,amphibians)- Urea
Uricotelic animals(birds,insects)-Uric Acid

41
Q

How does ammonotelic excretion take place ?

A

Metabolism of protein and nucleic acid generate nitro waste predom-ammonia
+ve-does not cost extra ATP to prodHIGHLY TOXIC
Aquatic animals -ammonia diffuse rapidly into water-continuosly excreted by diffusion across gills

42
Q

How deos ureotelic excretion take place ?

A

ammonia–>urea
but ATP cost
all mammals,amphibians,cartiligenous fish
but less toxic-urea highly soluble in water but animals need to concentrate urea in urine-avoid too much water loss

43
Q

How does Uricotelic excretion take place ?

A

insects,reptiles,birds,some amphibians
water-insoluble excreted as semi-solid (low toxicity)
so retains more water when eliminating nitrogenous waste

44
Q

How does the invertebrate excretory system of a flatworm work ?

A

live in freshwater
excrete water through tubules (flame cells)
tubule &flame cell form PROTONEPHRIDIUM
ECF enters tubule-filtration pressure diff cause ECF to filter through spaces into excretory pores.

45
Q

How does the invertebrate excretory system of a earthworm work ?

A

-segmented- contain fluid filled cavities :COELOM
-Blood is filtered ;waste products diffuse directly into tissues into COLEUM
-coleomic fluid is swept through cilliated nephrostomes
where dilute urine leaves from

46
Q

How does invertebrate excretory system work in insects ?

A

1.)Uric acid ,Na+,K+ actively tranported into malpighian tubs
2.) H2O is draen into malpighian tubules osmotically flushing tubule content into gut
3.) Na+ & K+ actively transported from hingut& rectum to coleomic fluid water follows
4.)Uric acid precipitates in return and excreted along with its waste

47
Q

What does the nephron consist of ?

A

Renal corspuscle (glomerulas & bowmans capsule
renal tube