Circulation Strategies Flashcards
Do all animals have circulatory systems?
no – some lack circulatory systems, but have mechanisms for propelling fluids around their bodies
Which animals lack circulatory systems?
- sponges and flatworms
- cnidarians
- echinoderms
- nematodes
How do sponges and flatworms propel fluids around their bodies without a circulatory system?
ciliated cells move water within body cavity
How do cnidarians propel fluids around their bodies without a circulatory system?
ciliated cells move water within body cavity
What type of circulatory system do insects have?
- open circulatory system
- tubular heart forces fluid in one direction into hemocoel, and ostia (holes) allow hemolymph to return to heart
What type of circulatory system do annelids have?
- polychaetes: open circulatory system
- oligochaetes: closed circulatory system
- circulate interstitial fluid with cilia or muscular contractions of body wall
What type of circulatory system do molluscs have?
- most have open systems
- only cephalopods have closed systems
Why do cephalopods have closed circulatory systems?
squids are highly active, therefore have closed systems to provide more O2 to tissues so they can be more metabolically active
How many hearts do cephalopods have?
three
- systemic heart: pumps blood to body tissues
- branchial hearts (2): pump blood through gills
What type of circulatory system do crustaceans (arthropods) have?
open circulatory system
- heart pumps fluid around, and ostia return fluid to heart
- have some control over distribution of blood flow in body*
Why do circulatory systems of crustaceans (arthropods) become more complex in larger animals?
have more tissues that need to be bathed
How much space does air or hemolymph take up in insects? Why is this a challenge?
70% of animal
- tracheal system takes up about 30% of body
- hemocoel takes up about 30-40% of body
- only takes up 5% in humans – much smaller volume, with more control
What type of circulatory system do urochordates (tunicates) have?
open system
- tubular heart at base of digestive tract
What type of circulatory system do cephalochordates (lancelets) have?
closed system with few open sinuses
- tubular heart at base of digestive tract and pulsatile blood vessels
What type of circulatory system do vertebrates (fish, amphibians, reptiles, birds, mammals) have?
closed system
How do nematodes propel fluids around their bodies without a circulatory system?
muscle contraction moves interstitial fluids
How do echinoderms propel fluids around their bodies without a circulatory system?
water vascular system used to move O2 and nutrients
What type of circulatory system circuit do water-breathing fish (jawed vertebrates) have?
single circuit
- some fish have accessory hearts in tail that helps pump blood back to heart
What type of circulatory system circuit do air-breathing tetrapods (jawed vertebrates) have?
double circuit
- pulmonary: right side of heart perfusing lung
- systemic: left side of heart perfusing other tissues
Single-Circuit, Closed Circulatory System – Water-Breather
Describe the single circuit of blood flow.
- cardiac output leaves heart
- cardiac output passes through respiratory (gills, branchial) capillaries for O2 uptake and CO2 excretion
- cardiac output travels to body
- cardiac output passes through systemic (peripheral; tissue) capillaries for tissue O2 delivery and CO2 removal
- cardiac output returns to heart
Single-Circuit, Closed Circulatory System – Water-Breather
Does each capillary bed have small or large resistance? How does this affect pressure in the circuit?
large resistance
- RBCs are forced through capillaries – need large pressure to pump them through
- leftover pressure needs to pump cells through the other capillary bed
- pressure drop for this circuit is large
Single-Circuit, Closed Circulatory System – Water-Breather
How does Ohm’s law apply to vessel resistance?
vessel resistance to blood flow in gills and tissues is additive
What are the 4 chambers of fish (teleost) hearts?
- sinus venosus
- atrium – contractile (cardiac muscle)
- ventricle – contractile (cardiac muscle)
- bulbus arteriosus (or conus arteriosus)
What are the two contractile chambers of fish (teleost) hearts? How do they function?
atrium and ventricle
- contract in sequence, and generate sufficient blood pressure to propel blood around entire body
- wall thickness is indicative of blood pressure it can generate – atrium thinner