Circulation 1

Question 1

what organisms lack circulatory systems (2)

Answer 1

• unicellular organisms
• small metazoans

Question 2

what do organisms without a circulatory system rely on to transport molecules

Answer 2

• diffusion, which can be rapid over small distances

Question 3

how to large animals deal with limits to diffusion (2)

Answer 3

• circulation
• they move fluid through their bodies by bulk flow or convective transport

Question 4

which organisms have a circulatory system

Answer 4

• most metazoans larger than a few cells

Question 5

what are the major functions of circulatory systems (6)

Answer 5

transport:
- oxygen
- carbon dioxide
- nutrients
- waste products
- immune cells
- signalling molecules

Question 6

how do circulatory systems move fluids

Answer 6

• by increasing pressure of the fluid in one part of the body

Question 7

describe the flow of fluid through the body in terms of pressure

Answer 7

• flows “down” the pressure gradient

Question 8

what are the three main components needed for a circulatory system (3)

Answer 8

• pump or propulsive structures to create high pressure
• system of tubes, channels, or spaces
• fluid that circulates through the system

Question 9

types of pumps (3)

Answer 9

• chambered hearts
• skeletal muscle
• pulsating blood vessels

Question 10

pumps: chambered hearts (2)

Answer 10

• contractile chambers
• blood enters atrium, and is pumped out by ventricles

Question 11

pumps: skeletal muscle

Answer 11

• squeeze on vessels to generate pressure

Question 12

pumps: pulsating blood vessels

Answer 12

• peristalsis; rhythmic contractions of vessel wall pumps blood

Question 13

how does the circulatory system prevent back flow

Answer 13

• one-way valves help to ensure unidirectional flow

Question 14

types of fluid (4)

Answer 14

• blood
• hemolymph
• interstitial fluid
• lymph

Question 15

fluids: blood

Answer 15

• fluid that circulates within the vessels of a closed circulatory system

Question 16

fluids: hemolymph

Answer 16

• fluid that circulates in an open circulatory system

Question 17

fluids: interstitial fluid (2)

Answer 17

• extracellular fluid that directly bathes the tissues and exists between cells
• similar composition to plasma

Question 18

fluids: lymph (2)

Answer 18

• fluid that circulates in the lymphatic system
• fluid that has filtered out of the vessels

Question 19

lymphatic system (2)

Answer 19

• secondary circulatory system of vertebrates
• carries lymph that has filtered out of the vessels

Question 20

open circulatory system (3)

Answer 20

• circulatory fluid comes in direct contact with the tissues in sinuses (open spaces)
• circulatory fluid mixes with interstitial fluid
• no control on how fluid returns to the hearts

Question 21

closed circulatory system (3)

Answer 21

• circulating fluid remains within vessels and does not come in direct contact with the tissues
• circulating fluid is distinct from interstitial fluid
• molecules must diffuse across vessel wall

Question 22

multicellular animals that lack circulatory systems (3)

Answer 22

• sponges
• cnidarians
• flatworms

Question 23

why do sponges, cnidarians and flatworms lack circulatory system

Answer 23

• they have mechanisms for propelling fluids around their body

Question 24

what mechanisms do sponges and flatworms have to makeup for their lack in circulatory system

Answer 24

• ciliated cells move water within body cavity

Question 25

what mechanisms do cnidarians use to replace a circulatory system

Answer 25

- muscular contractions of body wall pump water in and out of body cavity

Question 26

circulatory system: annelids (2) - mechanism - open or closed

Answer 26

- polychaetes circulate interstitial fluid with cilia or muscular contractions of the body wall - circulatory system can be open (polychaetes) or closed (oligochaetes)

Question 27

circulatory system: molluscs (2) - structures - open vs closed

Answer 27

- all have hearts and some blood vessels - most have open systems (clams), while only cephalopods have closed systems (squid)

Question 28

circulatory system: arthropods - crustaceans (4) - structures - open vs closed - complexity - control

Answer 28

- all have one or more hearts and some blood vessels - all have open systems - circulatory systems become more complex in larger crustaceans - some control over distribution of blood flow in body

Question 29

circulatory system: arthropods - insects (3) - open vs closed - structures - gas transport

Answer 29

- relatively simple open circulatory system - multiple, contractile “hearts” along dorsal vessels - use tracheal system for most gas transport

Question 30

phylum chordata (3)

Answer 30

- invertebrate: urochordates (tunicates) - invertebrate: cephalochordates (lancelets) - vertebrates (fish, amphibian, reptiles, birds, mammals)

Question 31

circulatory system: urochordates (2) - open vs closed - structures

Answer 31

- open circulatory system - tubular heart at base of the digestive tract

Question 32

circulatory system: cephalochordates (2) - open vs closed - structures

Answer 32

- closed system with a few open sinuses - tubular heart at base of the digestive tract and pulsating blood vessels

Question 33

circulatory system: vertebrates - open vs closed

Answer 33

- all have closed systems

Question 34

describe the evolutions of circulatory systems (4)

Answer 34

- first evolved to transport nutrients to body cells - began to serve a respiratory function very early - closed systems evolved independently in jawed vertebrates, cephalopods, and annelids - closed systems evolved in combination with specialized oxygen carrier molecules

Question 35

why did closed systems evolve/what is its advantage (2)

Answer 35

- increased blood pressure and flow - increased control of blood distribution

Question 36

why did closed systems with specialized O2 carrier molecules evolve

Answer 36

- to support high metabolic rates

Question 37

which organisms have an open circulatory system (4)

Answer 37

- urochordata - annelida - arthropoda - mollusca

Question 38

which organisms have a closed circulatory system (4)

Answer 38

- vertebrates - mollusca: cephalopods - cephalochordata (some open sinuses) - annelida

Question 39

how does the circulatory system fit into O2 delivery (4)

Answer 39

- acts in internal convection - quickly saturates respiratory pigment with O2 - pumps blood to where and when it is needed (changing vessel radius) - rapidly unloads O2 from blood to mitochondria

Question 40

when will the body experience increased O2 needs

Answer 40

- during all activities

Question 41

what are the ways to provide O2 to the body during activity (2)

Answer 41

- heart pumps mor blood per unit time (increased cardiac output) - tissues extract more O2 from capillaries (O2 content in venous blood will decrease)