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Lecture outline
Animal BauplansKey features of body plans (cont.)
Excretion and osmoregulationExcretion and osmoregulation Circulation and Gas ExchangeCirculation and Gas Exchange
Bauplans: key features Excretion and osmoregulation: overview
Excretion, defined: ridding body of metabolic wastes Carbon dioxideCarbon dioxide Water (if in excess)Water (if in excess) Nitrogenous and other wastes (=many are toxic)Nitrogenous and other wastes (=many are toxic)
Excretion usually tied to osmoregulationCO2 often excreted separatelyExcretion ≠ removal of solid waste
Bauplans: key features Excretion and osmoregulation
Nitrogenous wastes & water conservation Protein digestion Protein digestion nitrogenous wastes nitrogenous wastes
Excess amino acids are “deaminated”
Amine groups incorporated into waste molecules
Bauplans: key features Excretion and
osmoregulation Osmoregulation
and habitat What if osmolarity What if osmolarity
changes? changes? Osmoconformers Osmoregulators
Estuary: fresh water seawater
Bauplans: key features Excretion and osmoregulation
Osmoregulation and habitat What if osmolarity changes (cont.)?What if osmolarity changes (cont.)?
Most osmoconformers can osmoregulate (a bit)Most osmoregulators have limits to
osmoregulationOsmoregulation can occur at the cellular level
Example: Cell placed in hypotonic solution Example: Cell placed in hypotonic solution might initially swell, then respond by excreting might initially swell, then respond by excreting salts. (Why would this help?)salts. (Why would this help?)
Bauplans: key features Excretion and osmoregulation
Specialized structures Water expulsion vesicles (as in various Protista)Water expulsion vesicles (as in various Protista)
Accumulate water expel it to the outside Requires energy. Mechanism? Possibly in Porifera?
Bauplans: key features Excretion and osmoregulation
Specialized structures Nephridia: Nephridia:
Tubules acquire water/and or ions at one end and excrete wastes through pores
Bauplans: key features Excretion and osmoregulation
Specialized structures NephridiaNephridia
Protonephridia: proximal end closed
Metanephridia: proximal end open
Bauplans: key features Circulation and gas exchange
Overview Nutrients, wastes, and gases move through Nutrients, wastes, and gases move through
the bodythe body Transport systems allow for movement Transport systems allow for movement
beyond diffusionbeyond diffusion Origin of fluid for transportOrigin of fluid for transport
Internal body fluids; external fluids (i.e. Porifera)
Movement of fluids through/within body cavity may occur instead of or in addition to movement within a “true” circulatory system.
Bauplans: key features Circulation and gas exchange
Circulatory systems (true) CLOSED: blood remains within vesselsCLOSED: blood remains within vessels
Associated with well-developed coelomic cavity Composition of blood vs. coelomic fluid differs Exchange of dissolved materials occurs within
capillary beds (single cell layer to promote diffusion)
Bauplans: key features Circulation and gas exchange
Circulatory systems (true): OPEN: vessels exist, but open into hemocoelOPEN: vessels exist, but open into hemocoel
Associated with reduced coelom,peritoneum Less efficient than closed system?
Additional functions (i.e. hydrostatic)Additional functions (i.e. hydrostatic) Secondary systems have evolved to compensateSecondary systems have evolved to compensate
Bauplans: key features Circulation and gas
exchange Hearts and other pumping
mechanisms Pump blood/hemolymph; Pump blood/hemolymph;
maintain blood pressuremaintain blood pressure Several typesSeveral types
Contractile vessels (Annelida) Ostiate hearts (Arthropoda)
Allows entry of hemolymph Allows entry of hemolymph back into heart from the back into heart from the hemocoelhemocoel
Chambered hearts (Mollusca)
Bauplans: key features Circulation and gas exchange
Other key concepts (circulation) Myogenic vs. neurogenic control of contractionMyogenic vs. neurogenic control of contraction In general, freshly oxygenated blood/hemolymph is In general, freshly oxygenated blood/hemolymph is
first circulated to the head.first circulated to the head. Vessel diameter and flowVessel diameter and flow
Paradox: diameter flow rate Problem: need Problem: need lowlow flow at capillaries (why?) flow at capillaries (why?) Solution: Solution: total total cross-sectional area at cross-sectional area at
capillaries capillaries flow rate! flow rate!
Bauplans: key features Circulation and gas exchange
Gas exchange and transport OO22 uptake from air or water over uptake from air or water over moistmoist membrane membrane
(body surface or specialized structures) (body surface or specialized structures) Why moist?
Often diffuses into a “circulatory body fluid”, then Often diffuses into a “circulatory body fluid”, then to cellsto cells
COCO22 moves in opposite direction moves in opposite direction
Bauplans: key features Circulation and gas exchange
Gas exchange and transport Body fluids have relatively low OBody fluids have relatively low O22-carrying capacity-carrying capacity
Respiratory pigments increase that capacity O2 binds to a metal, usually copper or iron
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