Animal Lesson 6 Flashcards
Animals either what?
regulate their physiological parameters OR allow their
bodies to conform to external conditions
River otter example
A temperature regulatory. It’s able main body temp no matter the outside temp.
Largemouth bass
A temperature conformer. Change and mimics with outside temp. Low outside temp = low body temp.
Regulators use what?
homeostatic mechanisms to control internal changes. Have large external fluctuations but have small internal fluctuations because if homeostatic mechanism.
Conformers allow what?
their internal condition to change in response to external changes. May be able to tolerate greater ranges for physiological parameters (capable of being alive with large fluctuations). Internal stability is possible in stable environments (live in environments that don’t change much. why they don’t live in Canada).
Physiological parameters being regulated?
- Thermoregulation
– Temperature - Osmoregulation
– Body water, and solute concentration (salt conc).
Thermoregulation
the maintenance of an internal temperature within a
tolerable range.
Why does body temperature matter?
Biochemical and physiological processes are sensitive to changes in temperature. ie. Enzyme reaction rates decrease when temp decreases. Proteins (include. enzymes) can denature when temp increases. Membrane fluidity (how much flow through membrane) can vary with temp.
Each animal species has an optimal internal temp range. Can be narrow or wide. Temps outside range impairs functioning, lead to death, so maintaining thesis internal body temp is really important for the survival of the bodies we have.
Body temperature can be what?
variable or relatively stable
Poikilotherm
Body temperature of varies with environment
Homeotherm
have a relatively constant body temperature (mammals and birds)
Thermal strategies can be defined
based on what?
Source of heat. Where does the heat come from.
Endotherms
Endotherms rely on (internal) metabolism as their major heat source. From inside our bodies. We do this.
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))
Homeotherm and Endotherm example?
Mostly mammals and birds
Homeotherm and ectotherm example?
Some tropical reptiles; Antarctic and deep-sea fish. Only can survive in specific areas that don’t change in temp.
Poikilotherm and endotherm example?
Birds/mammals that undergo hibernation/torpor; some insects.
Poikilotherm and ectotherm example?
Most invertebrates, amphibians, reptiles, and fish.
Thermoregulation requires maintaining what?
equal rates of heat gain and heat loss
The two ways of maintaining equal rates of heat gain and heat loss?
Anatomical/physiological processes and behaviour responses.
Anatomical/physiological processes
- Evaporative heat loss
- Circulatory adaptations
- Metabolic heat production
- Insulation
Evaporative heat loss
o Water lost from moist surfaces cools/carries away heat. To cool down body, bring water to the surface.
o Adaptations that augment this cooling effect include
panting (encourages more water loss) and sweating.
Circulatory adaptations
Vasoregulation and Countercurrent heat exchangers.
Vasoregulation
common to endotherms and ectotherms. Capillary control blood flow. Vasoregulation is achieved via nerve impulses and hormones. Hypothalmulus starts it and controls how much of blood flow is spread out or narrowed down. Has Vasodilation and Vasoconstriction.
Vasodilation
relaxes smooth muscle walls of surface blood vessels.
–Allows more blood to flow from core to surface for cooling. Blood is warm, causes us to get cool because blood is getting close to surface and that’s cool.
Vasoconstriction
tenses smooth muscle walls of surface blood
vessels. Reduces blood flow from core to surface to prevent heat loss. It goes to brain, organs, and important parts that need to stay warm.
Countercurrent Heat Exchangers
found in birds and mammals. One vessel; with fluid going in one direction and another vessel really close to the first but fluid going in opposite direction. The close proximity allows for heat to be transferred back and forth. 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. The foot is cold cause water is cold.
Metabolic heat production
All metabolic activity produces heat. Endotherms have much higher metabolic rates than similarly sized
ectotherms.
Muscle contraction: Activity and Shivering. To produce heat.
Brown adipose tissue (some mammals). Fat with high concentration of mitochondria (why it’s brown). Cellular respiration produces heat instead of ATP (it doesn’t need the chemical energy). Organisms that live un arctic
Hypothalamus thermostatic function in human
thermoregulation
Homeostasis: Internal body temp about 36 to 38. Stimulus: Increased body temp. Sensor/control centre: thermostat in hypothalamus. Response: sweat and blood vessels in skin dilate. Body temp decreases. Back to Homeostasis.
Homeostasis: Internal body temp about 36 to 38. Stimulus: decreased body temp. Sensor/control: thermostat in hypothalamus. Response: shivering and blood vessels in skin constricted. Body temp increases and back to homeostasis.
Insulation
Fur, feathers, fat. Major adaptation to prevent heat loss in mammals and birds (especially those that live in cold areas).
Insulation for fur and feathers
Extra layer that traps a layer of air that doesn’t move around, so it can get warmed up by your internal body and that heat remains close to your skin.
Insulation for fat
Just an extra layer from the external temp.
Behaviour responses
Do things to ensure they can regulate their temp. ie. Shade seeking, sun basking, migration (moves to areas that are warm or cooler).
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?
Fewer
Water crosses cell membranes via what?
Simple diffusion (through membrane on their own) and facilitated diffusion (through membrane with help of protein). Don’t require energy.
Osmoregulation
the control of solute concentrations and the balance of water gain and loss from the body.
Physiological parameters for Osmoregulation
– 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. Certain organs will function better with certain types of solutes in a right kind of balance versus other parts.
* E.g., calcium vs potassium vs sodium vs urea vs certain amino acids vs water soluble hormones.
Osmosis
the movement of water across a selectively permeable membrane (with the membrane it’s just diffusion). Only water can go through the membrane so we end up will different conc. of solutes on both sides. Salts can only move with the help of something else. There is a natural tendency to try and equal out both sides of membrane.
Hyperosmotic solution
Lower free H2O concentration (not attached to a molecule). Higher solute concentration. Water will naturally flow to this side to balance out conc.
Hypoosmotic solution
Higher free H2O concentration. Lower solute concentration.
Animal cells are affected by what?
the relative osmolarity of their surrounding fluid.
Red blood cell example of hyper osmotic fluid
– Higher [solutes] outside cell
– Water leaves cells through osmosis
– Cells that lose too much water shrivel and (may) die
Red blood cell example of hypo osmotic fluid
– Lower [solutes] outside cell; (higher [S] inside)
– Water enters cells through osmosis
– Cells that gain too much water burst and die
Red blood cell example of isoosmotic fluid
– Same [solutes] inside and outside cell; (i.e., balanced).
– No net movement of water into or out of cells but still moves in and out.
What’s the fluid around the red blood cells
Plasma but can also be interstitial and lymph fluid.
Two ways animals maintain water balance
Osmoconformers are isoosmotic with their
environment and Osmoregulators maintain a stable internal osmolarity.
Osmoconformers are isoosmotic with their
environment
– No tendency to gain or lose water.
– All are marine.
– Some have stable osmolarities while others
tolerate variable osmolarities.
– ATP Actively transport specific solutes to maintain
homeostasis and have it be equal.
They live in environments that the same as there body. ie. sharks.
Osmoregulators maintain a stable internal osmolarity
– Found in marine, freshwater, and terrestrial
environments.
– A particular internal osmolarity is achieved by ATP
actively transporting solutes into or out of cells in hopes that the water will follow. Have help of enzymes.
* Water then flows in response to osmotic gradients
Live in environment different than their body.
Osmoregulation requires
Energy. Energy costs are reduced by minimizing
osmotic differences between body fluids and the surrounding environment. Different animals adapt differently.
– E.g., freshwater molluscs have adapted to have lower internal osmolarities than do marine molluscs to start at a level not as extreme to not spend to much energy.
If osmoregulation is energetically costly, why
aren’t all animals osmoconformers?
Access to more niches and more resources. Cost-benefit analysis.
The osmotic challenge faced by osmoregulators depends on what?
their environment.
Body fluids of most vertebrates ~ 300 mOsm/L
Freshwater lake/pond 20 – 40 mOsm/L
Seawater 1000+ mOsm/L
Freshwater osmoregulators
Gain water (through surface of gils).
Marine osmoregulators
Lose water
Terrestrial animals
Lose water because of evaporative tendencies of water.
Osmoregulation in a marine fish
Marine fish are hypoosmostic relative to the
seawater (hyperosmotic env.). Osmotic water
lost through gills and other parts of body surface. Loss of water increases internal osmolarity (so
how can the fish recoup water?). Marine fish
drinks seawater to replace water lost across the
body surfaces. Get water from food, but also
salt ions. Get water from drinking seawater, but
also salt ions. Excretion of salt ions from gills (Cl- cells (lots)). Osmotic water lost through gills and other parts of body surface (lots). Excretion of salt ions and small amounts of water in scanty urine from kidneys (low)
Osmoregulation in a freshwater fish
Freshwater fish are hyperosmostic relative to the
lake/river (hypoosmotic env.). Gain of water
decreases internal osmolarity (so how can the fish
get rid of excess water?). Freshwater fish
excretes water but must also take up salt ions to bring
internal osmolarity back up. Freshwater fish drinks
almost no water. Osmotic water gained through gills and other parts of body surface. Gain some ions in food, but also some water. Lots of excretion of large amounts of water in dilute urine from kidneys, but also salt ions lost. Uptake of salt ions by gills (Cl- cells they reverse depending in what they need).
Dehydration is a challenge for what?
terrestrial animals
Adaptations to reduce water loss (evaporation)
– Body coverings: cuticle, shells, keratinized skin
– Nocturnal: comes out at night when it’s not hot out.
terrestrial animals maintain water balance by what?
drinking and eating moist food and producing metabolic water through cellular respiration.
Animals control the solute concentration of an internal body fluid Via what?
Transport epithelia (layer of tissue) ie. skin (it protects lining of surfaces).
– One or more layers of epithelial cells specialized
for moving particular solutes in controlled
amounts and in specific directions.
Ie. simple and factilicted diffusion, and active transport (the active transport proteins with the help of ATP).
Which structural characteristic is most important
for transport epithelia involved in osmoregulation?
A large surface area
Transport epithelia have large surface areas
Some face the external environment directly
(e.g., gills) that have lots of branching. 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 some of extra solutes.
salt-excreting glands
How Seabirds, sea turtles, and marine iguanas
remove excess salt, taken in when drinking
sea water.
Salt glands have transport epithelia that rely on what?
countercurrent exchange. The animals look like they are crying but it’s just the extra salty fluid. They have secretory tubule and central duct that leads to outside. Salt concentration is always higher in the
blood vessel than the secretory tubule. The blood flow and secretion flow in opposite directions. Salt ions flow from blood vessel to secretory cell of transport epithelium to lumen of secretory tubule. Blood becomes less and less salty as it moves up. It naturally moves across.
Countercurrent exchange is a what?
homeostatic mechanism seen in multiple contexts.
