Finishing up topic from chapters 40 and 42 Flashcards
(39 cards)
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
