Finishing up topic from chapters 40 and 42 Flashcards
What is the internal environment of vertebrates made of
Interstitial fluid
what is homeostasis
Homeo = sameness, stasis = standing still
Homeostasis is the maintenance of a relatively stable internal environment despite changing external conditions
how does homeostasis work
Homeostatic mechanisms maintain internal conditions within a relatively small range of values … not at a constant value
Accomplished by complex coordination of processes via chemical and/or electrical signalling
How does homeostasis work
Homeostatic mechanisms maintain internal conditions within a relatively small range of values … not at a constant value
Accomplished by complex coordination of processes via chemical and/or electrical signalling
What did Bernard say about homeostasis
Homeostatic mechanisms maintain internal conditions within a relatively small range of values … not at a constant value
Accomplished by complex coordination of processes via chemical and/or electrical signalling
what did Cannon say about homeostasis
Cannon…
- Early 20th c. American Physiologist
- coined term homeostasis
what are Regulators
Regulator: uses mechanisms of homeostasis to moderate internal change in the face of external fluctuations, e.g. endotherms thermoregulate
what are Conformers
Conformer: allows some conditions within its body to vary with certain external changes, e.g. spider crabs osmoconform
why is osmoregulation important
- 71% of earth’s surface is covered with water
- This is mostly seawater
- Total freshwater, < 1% (0.01% of volume of sea water)
- Seawater: ~3.5% salt (1000 milliosmoles/L)
- Major ions: sodium and chloride
- Also: magnesium, sulfate, calcium
- Freshwater: total salt content: <0.1 mosm/L to > 10 mosm/L
what is the hyperosmotic side
Hyperosmotic side: higher solute concentration, lower free water concentration. Ex freshwater organisms
what is the hypoosmotic side
Hypoosmotic side: lower solute concentration, higher free water concentration. Ex marine bony fishes
what is isoosmotic
Isoosmotic with medium: body fluid = same osmotic pressure as medium. Ex most marine invertebrates
what is molarity
- Moles of solute / volume (L)
- 1 M substance = MW of substance in grams/L
what is osmolarity
- osmoles of solute particles / volume (L)
- 1 osmole = 1 mole of osmotically active particles
what is osmolality
osmoles of solute / Kg
what is an osmoconformer
Animal that does not actively adjust its internal osmolarity because it is isoosmotic with its environment
what are osmoregulatory animals
- Animal whose body fluid has a different osmolarity than that of the environment
- Animal that lives in a hypoosmotic environment must discharge excess water
- Animal that lives in a hyperosmotic environment must take in water
- Expends energy to control its internal osmolarity
How do freshwater animals deal with water balance
Freshwater animals
- Osmoregulators
- gain water by osmosis and food
- lose salts by diffusion and in urine
- regain salts in food and by active uptake from surroundings
- excrete large amounts of dilute urine
Some organisms like paramecium have contractile vacuoles which take water in from the cell, and then pump it out through a duct.
how do most marine invertebrates deal with water balance
- Most marine invertebrates
- Osmoconformers
- Total osmolarity = seawater
- Individual [Solute] ≠ seawater
how do most marine vertebrates deal with water balance
- Most marine vertebrates
- Osmoregulators
- lose water by osmosis
- gain water and salt in food and by drinking seawater
- dispose of salt by active transport out of gills and in urine
- produce small quantities of urine
what is Stenohaline
Stenohaline:
Organisms that cannot tolerate substantial changes in external osmolarity (greek stenos = narrow, close and halos = salt)
what is Euryhaline
Euryhaline:
Organisms that can tolerate substantial changes in external osmolarity (greek eurys = wide, broad)
describe transport equilibrium
Transport epithelium:
- Layers of specialized cells that regulate solute movements
- most important feature: ability to move specific solutes in controlled amounts in particular directions
- cells joined by tight junctions
- in most animals: arranged into tubular networks with extensive surface area
what are Secretory Tubules
Secretory tubules. There are several thousand secretory tubules in a nasal gland. Each tubule is lined by a transport epithelium surrounded by capillaries and drains into a central duct
What is countercurrent exchange
Countercurrent exchange. The secretory cells actively transport salt (NaCl) from the blood into the tubules. Blood flows counter to the flow of salt secretion. By maintaining a concentration gradient of salt in the tubule (blue), this counter-current system enhances salt transfer from the blood to the lumen of the tubule.
What is Anhydrobiosis
Ability to survive in a dormant state when an organism’s habitat dries up
Tardigrades which inhabit temporary ponds as well as droplets of water in soil and on moist plants. Can survive dehydration in a dormant state.
what the problem with living on land related to water
Largest Problem = desiccation
⇒ adaptations that can reduce water loss are key to survival on land
how can animals retain water
- Water loss reduced by
- Body coverings
- nocturnal habitat
- drinking and eating moist foods
- using metabolic water
what is food used for in animals
- Animals are heterotrophs that harvest chemical energy from the food they eat
- Ingested energy will be either
- Used to do work
- stored
- excreted
- released as heat
- Heat produced by metabolism
- Useless for doing work
- useful for maintaining body temperature
what is metabolic rate
- Amount of energy an animal uses in a unit of time; sum of all the energy-requiring biochemical reactions occurring over a given time interval
- Can be measured by monitoring an animal’s rate of
- Heat loss
- Oxygen consumption
- Carbon dioxide production
what is basal metabolic rate
Stable rate of energy metabolism measured in mammals and birds under conditions of minimum environmental and physiological stress (i.e. at rest with no temperature stress and after fasting)
what is standard metabolic rate
A measure that is similar to BMR but used for an animal with varying body temperature that is maintained at a selected body temperature
in other words:
an animal’s resting and fasting metabolism at a give body temperature
what influences metabolic rate
- Size
- internal work (chemical, osmotic, electrical, and mechanical)
- External work (for locomotion and communication)
- Tissue growth and repaire
- time of day
- season
- age
- sex
- stress
- type of food being metabolized
how can animals adjust to changing temperatures
- production of stress-induced proteins, e.g. heat-shock proteins
- in birds and mammals
- Adjusting the amount of insulation
- varying the capacity for metabolic heat production
- In ectotherms
- Adjustments at the cellular level
- production of cryoprotectants
what is Torpor
Torpor = physiological state in which activity is low and metabolism decreases
What is Hibernation
Hibernation = long-term torpor, evolved as an adaptation to winter cold and food scarcity, e.g. squirrel, bear
What is Estivation
Estivation = summer torpor, also characterized by slow metabolism and inactivity, e.g. some amphibians, fish, invertebrates
what is Daily torpor
Daily torpor, e.g. hummingbird
How can you hold your breath for a long time
- Have a lot of blood; store some in the spleen
- Have a lot of muscle myoglobin
- don’t work too hard
Respiratory adaptations of diving mammals
- Weddell seals in Antarctica can remain underwater for 20-60 minutes
- Elephant seals can dive to 1,500 m and remain underwater for 2 hours
The Weddell seal
- Can store large amounts of oxygen, mostly in blood (70%0 and muscles (25%)
- humans: 51 and 13% respectively
- Has huge speeln
- has high [myoglobin]
- Has adaptations that conserve oxygen
- chaging buoyancy to glide passively
- decreasing blood supply to muscles
- deriving ATP in muscles from fermentation once oxygen is depleted
