Lesson 4- Excretory System Flashcards
how is fluid balance maintained between the extracellular and intracellular fluid?
electrolyte homeostasis
The function of the excretory system?
-eliminate body wastes
-maintaining osmolarity of body fluids
what are electrolytes?
obtained from ingested foods, electrolytes are minerals that populate the intracellular and extracellular (including intravascular & interstitial fluid) fluid compartments
what does the extracellular compartment include?
- the interstitial fluid bathing body cells
- the intravascular fluid in blood vessels
what is our most important extracellular electrolyte?
sodium
other important ones are chloride and calcium ions
which are the principal intracellular electrolytes?
potassium and magnesium
what is osmosis? (amount of electrolytes control osmosis)
the flow of water between the extracellular and intracellular fluid compartments
what happens if we consume too much sodium?
drives water into the extracellular compartment and increases its volume – increase in volume of the intravascular compartment causes an increase in blood pressure
what happens when we consume too much sodium?
drives water into the extracellular compartment and increases its volume – increase in volume in the intravascular compartment causes an increase in blood pressure
what happens when magnesium and potassium concentrations increase?
drive fluid out of the extracellular compartment and into body cells
what is the primary system of osmoregulation in marine birds?
salt glands
what is the primary system of osmoregulation in fishes?
gill filaments
which organs consume the most energy (BMR) in humans?
liver - 27%
brain - 19%
skeletal muscles 18%
what are the costs of osmoregulation?
- difference in osmolarity of the animal<s body fluid and its environment
- permeable skin= harder to maintain a fixed gradient
- the amount of ATP required to operate the active transport pumps involved with moving solutes in and out of the body
who is an osmoregulator?
freshwater animals
terrestrial animals
who is an osmoconformer?
marine animals
how do mammals (not flying birds) get rid of nitrogenous wastes?
the liver converts ammonia into urea- a less toxic but metabolically expensive to generate- urea requires water though
how do animals without access to much water get rid of nitrogenous wastes?
birds, reptiles, insects and land snails eliminate wastes in the form of uric acid
what is the excretory tubule called for invertebrates?
nephridium
what is the excretory tubule called for vertebrates?
nephron
1. cortical nephron in a segment called the renal cortex
2. longer juxtamedullary nephrons that extend well into the renal medulla segment of the kidney
what is the most basic type of excretory system?
the proto-nephridium in flatworms-
dead end tubules
cilia inside flame bulb drives interstitial fluid through bulk flow
who has malpighian tubules?
animals with open circulatory systems
what is the excretory system of annelids?
the metanephridia - convoluted tubules associated with blood capillaries
