Animal: Lecture 6

Question 1

Animals do what or what to regulate physiological parameters?

Answer 1

Animals either regulate their
physiological parameters OR allow their bodies to conform to external conditions

Question 2

River otter vs. Largemouth bass?

Answer 2

• Regardless of environmental temperature, river otters are able to maintain their internal temperature. They are thermoregulatory (REGULATE and maintain stable)
• The largemouth bass pretty much conform to the environmental temperature. This makes them thermoconformers as they conform and vary with temperature.

Question 3

What do regulators do?

Answer 3

Regulators use homeostatic mechanisms to control internal changes.

• Despite large external fluctuations, there are small internal fluctiations

Question 4

What do conformers do?

Answer 4

Conformers allow their internal condition to change in response to external changes.
- They may be able to tolerate greater ranges for physiological parameters (cells are adapted to handle change)
- Internal stability is possible in stable environments (go to stable environments that don’t change much ~> tropical areas with an environment that rarely changes.

Question 5

What are the physiological parameters being regulated?

Answer 5

Thermoregulation (temperature regulation) and Osmoregulation (body water, and solute/salt concentration)

Question 6

What is thermoregulation?

Answer 6

Thermoregulation os the maintenance of a internal temperature within a tolerable range.

Question 7

Why does body temperature matter?

Answer 7

Biochemical and physiological processes are sensitive to changes in temperature
- Enzyme reaction rate decreases when temperature decreases.
- Proteins and enzymes can be denatured when temp increases
- Membrane fluidity can vary with temperature.

Each animal species has an optimal internal temperature range:
- can be narrow (small changes) or wide (large changes)
- Temperatures outside range impairs functioning, which could lead to death.

Question 8

Body temperature can be..?

Answer 8

Body temperature can be variable or relatively stable .

Question 9

Poiklotherm?

Answer 9

The body temperature of poikilotherms varies with environment. They have a wide range and can handle changes.

Question 10

Homeotherm?

Answer 10

Homeotherms have a relatively constant body temperatures. They have a narrow range and don’t really withstand changes.

Question 11

Thermal strategies?

Answer 11

Thermal strategies can be defined based on source of heat.

Question 12

Endotherms?

Answer 12

Endotherms rely on (internal)
metabolism as their major heat
source.

• not to say that we cannot get heat from sunbathing, but the majority of our heat comes from metabolic processes.

Question 13

Ectotherms?

Answer 13

Ectotherms rely primarily on
external environment as their
major heat source (i.e., don’t
produce enough body heat to
raise above external temperature;
rely mostly on behaviour)
- like sunbathing for a lizard on a rock.

Question 14

Source vs. range of temperatures?

Answer 14

Some endotherms are poikilotherms
and some ectotherms are homeotherms:
- Most mammals and birds are endotherms and homeotherms
- Most birds and mammals that undergo hibernation and some insects are poikilotherms and endotherms.
- Some tropical reptiles, as well as antarctic and deep-sea fish are ectotherms and homeotherms
- Most invertebrates, amphibians, reptiles and fish are ectotherms and poikilotherms.

Question 15

What does thermoregulation require?

Answer 15

Thermoregulation requires maintaining equal rates of heat gain and heat loss.

Question 16

Through which processes do we regulate our temperature?

Answer 16

Anatomical/physiological:
- Evaporative heat loss
- Circulatory adaptations
- Metabolic heat production
- Insulation

Behavioural responses

Question 17

Evaporative heat loss?

Answer 17

Evaporative heat loss:
- Water lost from moist surfaces cools/carries away heat
- Adaptations that augment this cooling effect include panting and sweating
- The blood brings heat up to the surface and cools it before bringing it back to the body

Question 18

Circulatory adaptations?

Answer 18

Vasoregulation:
* common to endotherms and ectotherms.
* ability to control blood vessels and capillaries

Countercurrent heat exchangers:
* found in birds and mammals
*vessels in one direction are close to vessels in another direction

Question 19

Vasoregulation?

Answer 19

Vasoregulation is achieved via nerve
impulses and hormones.
- hypothalamus sends out nerve impulses and hormones to control how much blood is being flown into capillaries.

Question 20

Vasodilation?

Answer 20

Vasodilation relaxes smooth muscle
walls of surface blood vessels
– Allows more blood to flow from core to surface for cooling
- causes us to get red because of the proximity to the surface - cools blood before its brought back.

Question 21

Vasconstriction?

Answer 21

Vasoconstriction tenses smooth
muscle walls of surface blood
vessels
– Reduces blood flow from core to
surface to prevent heat loss
– good when we are cold as the warm blood can be kept inside to make sure that our core body is kept functioning (brain, heart over fingers)

Question 22

Potential problem areas in maintaining body heat for goose?

Answer 22

Feet get cold in water??

Question 23

Countercurrent heat exchanges?

Answer 23

Heat is transferred between fluids flowing in opposite directions

Heat from warm arterial blood is transferred to cooler venous blood as it returns to the body core.

• Artery and vein are close and heat is transferred due to the proximity, keeping the blood warm as it reentered the body.

Question 24

Metabolic heat production?

Answer 24

All metabolic activity produces heat
- Endotherms have much higher metabolic rates than similarly sized
ectotherms

Muscle contraction
- Activity
- Shivering

Brown adipose tissue (some mammals)
-High concentration of mitochondria
- Cellular respiration produces heat instead of ATP
- animals in the arctic or up north have more of this

Question 25

Hypothalamus thermostatic function when hot?

Answer 25

Stimulus: increased body temperature Sensor/control center: thermostat in hypothalamus (two things) - response: sweat - response: blood vessels in skin dilate RESULT: body temperature decreases, homeostasis internal body temperature (36-38) is reached

Question 26

Hypothalamys thermostatic function when cold?

Answer 26

stimulus: decreased body temperature sensor/control: thermostat in hypothalamus (2 responses) - response: shivering - response: blood vessels in skin constrict RESULT: body temperature increases; homeostatic internal body temperature (36-38) is reached

Question 27

Insulation?

Answer 27

Fur, feathers, fat - Major adaptation to prevent heat loss in mammals and birds Traps air between the skin and the fur or feathers. They move around and the layer of air is warmed by the internal body temperature. This warm air remains close to skin and fur, keeping the animal warm Blubber is thick and warm and a good insulator (especially for aquatic animals)

Question 28

Behavioural responses?

Answer 28

Shade seeking, sun basking, migration. - They can be fairly easy tasks that do not reqire much energy like sun basking, or they can be huge energy takers--MIGRATION

Question 29

Blubber is a thick layer of vascularized adipose tissue under the skin of all cetaceans, pinnipeds, penguins, and sirenians. Would you expect blubber to contain more or fewer blood vessels than human skin?

Answer 29

Fewer!

Question 30

Water crosses cell membranes via... A. Simple diffusion B. Facilitated diffusion C. Active transport D. A and B E. A and C

Answer 30

D! both simple diffusion and facilitated diffusion!

Question 31

What is osmoregulation?

Answer 31

Osmoregulation is the control of solute concentrations and the balance of water gain and loss from the body

Question 32

What are the physiological parameters for osmoregulation?

Answer 32

Body water (volume) * E.g., in blood, in interstitial fluid, within cells Total solute concentration * E.g., calcium + potassium + sodium + urea + certain amino acids + water soluble hormones Individual solute concentrations * E.g., calcium vs potassium vs sodium vs urea vs certain amino acids vs water soluble hormone - these change based on the area: something needed in a liver cell will be in high concentration in those areas but low in the brain for example.

Question 33

What is osmosis?

Answer 33

Osmosis is the movement of water across a selectively permeable membrane

Question 34

Osmosis example in a beaker?

Answer 34

On one side we have Hyperosmotic solution: higher solute concentration and lower free H2O concentration. On the other side we have Hypoosmotic solution: lower solute concentration and higher free H2O concentration - Solutes can not cross the membrane - Water will want to equalize the concentrations on both sides, therefore it will go to the hyper osmotic side!

Question 35

What are animal cells affected by?

Answer 35

Animal cells are affected by the relative osmolarity of their surrounding fluid.

Question 36

Hyperosmotic fluid?

Answer 36

- higher concentration of solute outside the cell - Water leaves cells through osmosis - Cells that lose too much water shrivel and may die as the water will all go to the environment.

Question 37

Hypoosmotic fluid?

Answer 37

Lower concentration of solutes outside the cell, higher concentration of solutes inside. - Water enters cells through osmosis - Cells that gain too much water burst and die.

Question 38

Isoosmotic fluid?

Answer 38

- Same concentration of solutes inside and outside the cell ( it is balanced ) - No net movement of water into or out of cells.

Question 39

What might the fluid be?

Answer 39

Blood plasma, hemolymph, or interstitial

Question 40

Two strategies for maintaining water balance?

Answer 40

Osmoconformers and osmoregulators

Question 41

Osmoconformers?

Answer 41

Osmoconformers are isosmotic with their environment (like sharks): - No tendency to gain or lose water - All are marine - Some have stable osmolarities while other tolerate variable osmolarities. - Actively transport specific solutes between membranes to maintain homeostasis. (REQUIRES ATP)

Question 42

Osmoregulators?

Answer 42

Osmoregulators maintain a stable internal osmolarity – Found in marine, freshwater, and terrestrial environments – A particular internal osmolarity is achieved by actively transporting solutes into or out of cells --- Water then flows in response to osmotic gradients Kidneys: they will move solutes from one place to make sure that there's water that flows in and through to balance things out.

Question 43

osmoregulation requires...?

Answer 43

Osmoregulation requires energy.

Question 44

Cost of osmoregulation energy?

Answer 44

Energy costs are reduced by minimizing osmotic differences between body fluids and the surrounding environment – E.g., freshwater molluscs have lower internal osmolarities than do marine molluscs - Start at less extreme to not have to spend more or as much energy maintaining osmoregulation in freshwater.

Question 45

If osmoregulation is energetically costly, why aren’t all animals osmoconformers?

Answer 45

This gives the access to more niches and resources. Benefits > costs

Question 46

Osmotic challenges depend on..?

Answer 46

The osmotic challenge faced by osmoregulators depends on their environment.

Question 47

Substance vs. Solute concentration?

Answer 47

Body fluids of most vertebrates = ~300 mOsm/L Freshwater lake/pond = 20-40 mOsm/L Seawater = 1000+ mOsm/L

Question 48

Natural tendencies of osmoregulators?

Answer 48

* Freshwater osmoregulators → gain water * Marine osmoregulators → lose water * Terrestrial animals → lose water

Question 49

You may have heard the expression “drinking like a fish”, but do fish drink water?

Answer 49

Some do and some don't

Question 50

Osmoregulation in a marine fish?

Answer 50

Marine fish are hypo osmotic relative to the seawater (hyper osmotic environment) - Loss of water increases internal osmolarity (so how can the fish recoup water?) 1. Osmotic water lost through gills and other parts of body surface 2. Get water from food, but also salt ions as well as getting water from drinking seawater (also brings salt ions) 3. Excretion of salt ions from gills (Cl-) and in small amounts of water in scanty urine from kidneys (scanty = high concentration of salt and low amount of urine) RESULT: Marine fish drinks seawater to replace water lost across the body surface

Question 51

Osmoregulation in a freshwater fish?

Answer 51

Freshwater are hyper osmotic relative to the lake/river (hypo osmotic environment) - Gain of water decreases internal osmolarity (so how can the fish get rid of excess water?) 1. Osmotic water gained through gills and other parts of the body surface 2. Gain some ions in food, but also some water. 3. Uptake of salt ions by Cl- cells in the gills 4. Excretion of large amounts of water in dilute urine from kidneys, but also salt ions are lost. RESULT: Freshwater fish excretes water but must also take up salt ions to bring internal osmolarity back up. Freshwater fish drinks almost NO water.

Question 52

Dehydration?

Answer 52

Dehydration is a challenge for terrestrial animals.

Question 53

Adaptations to reduce water loss?

Answer 53

Adaptations to reduce water loss – Body coverings: cuticle, shells, keratinized skin (prevent water evaporation) – Nocturnal (come out in cooler environments)

Question 54

How do terrestrial animals maintain water balance?

Answer 54

Maintain water balance by drinking and eating moist food and producing metabolic water through cellular respiration

Question 55

Animals control..?

Answer 55

Animals control the solute concentration of an internal body fluid.

Question 56

How do they control this?

Answer 56

Via transport epithelia – One or more layers of epithelial cells specialized for moving particular solutes in controlled amounts and in specific directions. This process takes ATP.

Question 57

Which structural characteristic is most important for transport epithelia involved in osmoregulation? A. A large lumen (internal space) B. Several layers of thick muscle C. A large surface area D. Rigidity

Answer 57

C. A large surface area!

Question 58

Transport epithelia have large surface areas (ensures exchange occurs)?

Answer 58

Some face the external environment directly (e.g., gills) - But many line tubular networks that connect to the outside by an opening on the body surface (e.g., those in salt glands or kidneys) -Transport epithelia are closely connected to circulatory fluid to remove extra salts

Question 59

Salt excreting glands?

Answer 59

Seabirds, sea turtles, and marine iguanas remove excess salt, taken in when drinking sea water, through salt-excreting glands - This is through sneezing or tear ducts, which remove the salt

Question 60

Salt glands and countercurrent exchange?

Answer 60

Salt glands have transport epithelia that rely on countercurrent exchange to draw in extra salts from blood to inside. - Salt concentration is always higher in the blood vessel than the secretory tubule. The blood becomes less salty as time move on!

Question 61

Animals can do what with their environmental conditions?

Answer 61

Animals can regulate physiological parameters or conform to environmental conditions

Question 62

Animals have what mechanisms for thermoregulation?

Answer 62

Animals have anatomical, physiological, and behavioural mechanisms for thermoregulation

Question 63

Animals in different environments?

Answer 63

Animals in different environments have different osmotic challenges and osmoregulatory physiology

Question 64

Countercurrent exchange?

Answer 64

Countercurrent exchange is a homeostatic mechanism seen in multiple contexts