lecture-5,6

Question 1

Define homeostasis ?

Answer 1

maintance of stable internal environment for the preservation of the normal functioning of cells
-consistency in body temp
needs of cells in multicellular animal are served through exchanges with the internal

Question 2

What are cells surrounded by ?

Answer 2

surrounded by ECF maintaining the
1. ionic composition of ECF
2. solute conc of ECF (determines water balnce )
3. health of cells(eliminating nitrogeneous waste critical for normal cell function

Question 3

Chemical composition of the body ?

Answer 3

body water accounts for about 60% of total body weight
body water divided into locate dwithin cells and located wtihin cells and located outside cells.

Question 4

What does body water contain ?

Answer 4

contains many dissolved ions/substances in solution -fluid
ECF-(outside)
subdivided into plasma and interstitial fluid
ICF-(inside) hydrates interstitial space /interstitium
(consists if connective tissues=collagen)

Question 5

How does a species maintain homeostasis of its ECF ?

Answer 5

-its environment :salt/fresh water ,terrestial
-its lifestyle

Question 6

What do animal depend on ?

Answer 6

excretory systems to maintain
-volume,conc and the composition of their ECF and to excrete wastes
use filtration,secretion,reabsorption to regulate
1. osmolarity
2. ionic composition of ECF

Question 7

How do bats use blood as ‘fast food’ ?

Answer 7

feed on blood of animals once a day
blood=nutritious protein mainly water
bat takes large volumes of blood adn excrete water first
back at home -to digest its meal-noe excrete nitrogenous waste but with minimal water loss–>excretory system switches rapidly from prod lots of dilute urine-to very little conc unrine

Question 8

Define osmosis ?

Answer 8

water moves from a region of high water conc to 1 of lower water conc

Question 9

How is homeostatic balance maintained in animals ?

Answer 9

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

Question 10

How does water move about ?

Answer 10

passive transport of water acrss membrane requires
1. semi-permeable menbrane permitting water but not solute movment
2. a difference in solute concentration

ALL ANIMALS= NO ACTIVE TRANSPORT

Question 11

What are water channels ?

Answer 11

aqua porins
-possess pores allowing water to pass from one side of membrane to the other,according to osmotic gradient
found in tissues which trnsport large volumes of water per day
tubules of kidney

Question 12

Osmotic pressure in solution ?

Answer 12

solute will displace water lowering the water concentration so water will move to left
the amount of pressure that needs to be applied to just stop this movement is OSMOTIC PRESSURE^^^^

Question 13

Define molarity of solution ?

Answer 13

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

Question 14

What is Van’t Hoffs law ?

Answer 14

dependant on the total number of dissolved particles present in a solution which is measured in osmoles
1 osmole= 1 mole avogadros

Question 15

Define Osmolarity ?

Answer 15

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

Question 16

Define Osmolality ?

Answer 16

no of osmoles per kg of solution

Question 17

How does water move in fishies ?

Answer 17

move from a hypoosmotic (low) to hyperosmotic (highosmotic pressure :fish plasma) solution to make them isomotic
osmotic eqm is reached

Question 18

How does the osmolarity of ECF & ICF remain the same ?

Answer 18

major contribution ICF osmolarity -K+
Major contributions ECF-Na+,Cl- ions
major diff between plasma & ISF is that proteins levels are low in ISF

Question 19

What are non -permeating solutes ?

Answer 19

cannot cross cell membranes ;create a ‘persistent’ osmotic gradient
eg. plasma proteins create COLLOID OSMOTIC PRESSURE (oncotic pressure)
means that plasma has a slightly higher osmolarity than ISF –>prevents huge blood loss of fluid volume

Question 20

What are penetrating solution ?

Answer 20

can diffuse through cell membrane ;can alter the osmotic-pressure gradient.
Solvent drag=when water is crossin ga membrane ,a solute may ohysically move it

Question 21

What is a isotonic solution ?

Answer 21

is one that has the same osmotic pressure as that of the other cells
solutions that are isotonic are not always isotonic in long run

Question 22

Define isotonic solution ?

Answer 22

one into which cells can be placed without their volumes being affected

Question 23

Define Hypotonic solution ?

Answer 23

has an osmotic pressure less than that of cells ;cells will swell because of an osmotic influx of water

Question 24

Define Hypertonic solution ?

Answer 24

Has greater osmotic pressure than that of cells ;cell will shrink because of osmotic water loss

Question 25

What is tonicity ?

Answer 25

measure of osmolarity or osmolality

Question 26

What is stenohaline ?

Answer 26

species that can tolerate only a narrow range of environmental /ambient salinity
most open oceans invertebrates species are stenohaline osmoconformers :rarely experience dilution off seawater

Question 27

Define euryhaline ?

Answer 27

species
especially estuarine species can survive wide range of salinity
are likely osmosregulators

Question 28

What is the diff between osmoconformers vs osmoregulators ?

Answer 28

aqautic animals either conform to osmolarity or they expend metabolic energy to maintain constant internal osmolarity
most marine invertebrates =osmoconformers

Question 29

How does osmolarity in ECF work ?

Answer 29

is in eqm with external environment
energy saving
other aqautic /marine invertbrates are osmoregulators
maintains constant internal osmolarity

Question 30

Eg of a sea thing that osmoconforms /osmoregulates in diff conditons ?

Answer 30

Brine shrimp
Hyperosmotic regulator in dilute sea water : keeps tissue fluid osmolarity above environmental,by concentrating saltsacross gill membranes
Hyposmotic regulator:
in hypersaline water
keeps tissue fluid osmolarity below environmental level by active transport of NaCl from ECF out across gill membranes

Question 31

What are freshwater teleost fish to the water they live in ?

Answer 31

hyperosmotic to water they live in
blood is hyperosmotic compared to the environment
salts must be ratained and excess water excreted

Question 32

What are salt water teleost fish to the water they live in ?

Answer 32

hyperosmotic to water they live in
blood is hyposmotic compared with environment
water must be reatined and excess alts excreted

Question 33

How does ion uptake occur in frehwater fish ?

Answer 33

freshwater animals lose ions in urine
also lose ions through direct outward diffusion across the gills these need to be replaced

Question 34

What is water conservation ?

Answer 34

is essential
need to eliminate or conserve salt depending on the animals diet :
-Herbivore :tend to conserve sdalt
-Marine birds :tend to eliminate salt

Question 35

What do some birds have ?

Answer 35

Nasal salt bridges
excrete excess salt :secondary active transport of Cl- ions –>NaCl empties into nasal cavity
As marine bird kidneys are not sufficient to maintain blood hyposmotic to seawater

Question 36

What is filtration ?

Answer 36

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

Question 37

Define Secretion and rebsorption ?

Answer 37

Active processes that alter the filtrate composition in tubule

Desired function depends upon animals environemnt :
Freshwater :excrete water,retain salts
Marine and land animals:excrete salts,retain water

Question 38

Excretion of nitrogenous waste ?

Answer 38

1. Ammonotellic: aqautic invertebrates and most bony fishes
2. Ureotelic:most amphibians
3. uricotellic :birds,insects ,reptiles

Question 39

How does Ammonotelic excretion work ?

Answer 39

Metabolism of protein and nucleic acids generate nitrogenous wastes ,predominantly ammonia
+ not cost extra ATP to prod but highly TOXIC
Aquatic animals
Ammonotelic excretion :
Ammonia diffuses rapidly into and is highly soluble in water
usually continuosly excreted by diffusaion across gills

Question 40

How does Ureotelic excretion work ?

Answer 40

animals detocify ammonia–> convert it to urea
mammals all
urea is highly soluble in water but animals need mechanism to concentrate urea to avoid toomuch water loss
Prod urea-less toxis but costs ATP

Question 41

What us uric acid ?

Answer 41

animals detocify ammonia–>uric acid
Insects ,reptiles,birds
water soluble ,excreted as semi-solid
enables conversion of water during elimination of nitrogenous waste

Humans are ureotelic, but we also excrete uric acid (from nucleic acid metabolism): if too much in ECF →gout. We also excrete ammonia…

Question 42

What are flatworms ?

Answer 42

live in freshwater
excrete water through a network of tubules ;end are fame cells
-tubule +flame cell=protonephridium
-ECF enters tubules by filtration ;the pressure diff causes ECF to filter through the spaces into excretory pores

More ions are reabsorbed → urine is more dilute than ECF.

Question 43

How does the excretory system of earthworms work ?

Answer 43

segemted :filled with fluid in cavities:Coelom
-Blood is filtered :waste products diffuse directly from tissues into the coelom
-Coelom fluid is swept into metanephridia through ciliated nephrostomes
nephrodiapores =where dilute urine leaves