Circulatory Systems in animals

Question 1

why is cs required

Answer 1

for transportation of materials within the body

exchange of materials with the external environment

Question 2

why do simple animals lack cs

Answer 2

• many or all cells are in direct contact with the external environment
• direct diffusion is sufficient for their needs
• materials can be transported by diffusion through short distances within the body

Question 3

what simple animals lack a cs

Answer 3

cnidarians
flatworms

Question 4

why have cs in animals evolved in complex animals to exchange materials between cells and immediate surroundings?

Answer 4

• as they increase in size and complexity, the amount of materials moving in and out the body also increase
• the distance materials have to be transported within the body
• many or all the cells are not in direct contact with their external environment
• diffusion isn’t sufficient to transport materials throughout the body

Question 5

substances transported within the body

Answer 5

1. respiratory gases (O2 and CO2)
2. nutrients (glucose, amino acids, fatty acids, vitamins)
3. waste products of metabolism (urea,ammonia)
4. hormones
5. antibodies

Question 6

3 basic components of a cs

Answer 6

1. muscular pumping device/heart
2. circulatory fluid (blood/hemolymph)
3. interconnected vessels

Question 7

describe blood cs in animal kingdom

Answer 7

• a cs has 3 basic components: a muscular pumping device (heart, interconnected vessels and circulatory fluid (blood/hemolymph)
• circulatory fluid flows through vessels mainly due to pressure generated by the heart
• the cs functionally connects the fluid environment of body cells to organs that exchange gases, absorb nutrients and dispose waste by transporting fluids throughout the body
• various degrees of complexity in arrangement of cs can be seen in animal kingdoms

Question 8

what does cs functionally connect

Answer 8

the fluid environment of body cells to organs that exchange gases, absorb nutrients and dispose waste by transporting fluids throughout the body

Question 9

how does circulatory fluid flow through vessels

Answer 9

circulatory fluid flows through vessels mainly due to pressure generated by the heart

Question 10

2 types of cs

Answer 10

open cs

closed cs

Question 11

define open cs

Answer 11

it’s a cs in which a fluid called hemolymph bathes tissues and organs directly

Question 12

describe open cs

Answer 12

• it’s a cs in which a fluid called hemolymph bathes tissues and organs directly
• there’s no distinction between circulatory fluid and interstitial fluid surrounding cells
• the heart pumps hemolymph through circulatory vessels into spaces (interconnected sinuses) which surround body tissues
• chemical exchange occurs directly between hemolymph and body cells
• back flow of hemolymph takes place via pores (ostia) with valves found in heart during relaxation
• this cs has evolved in some invertebrate phyla such as Arthropoda and some molluscs groups

Question 13

how does chemical exchange in an open cs occur

Answer 13

directly between hemolymph and body cells

Question 14

how does backflow of hemolymph occur?

Answer 14

via pores (ostia) with valves found in heart during relaxation

Question 15

where can an open cs be found

Answer 15

some invertebrate phyla such as Arthropoda and some molluscs groups

Question 16

define closed cs

Answer 16

it is a cs where blood is restricted to vessels and kept apart from interstitial fluid

Question 17

describe closed cs

Answer 17

• its a cs where blood is restricted to vessels and kept apart from interstitial fluid
• blood is pumped by the heart/s into large vessels
• these large vessels branch into small vessels and they penetrate organs
• chemical exchange occurs between blood and interstitial fluid and interstitial fluid and body cells
• it may contain one or more hearts
• this type of cs can be seen in vertebrates and invertebrates such as annelids
• in comparison to open cs, closed cs enable effective delivery of oxygen and nutrients to cells of larger and more active animals due to relatively high BP

Question 18

how does chemical exchange occur in closed cs

Answer 18

chemical exchange occurs between blood and interstitial fluid and interstitial fluid and body cells

Question 19

where can closed cs be seen

Answer 19

in vertebrates and invertebrates such as annelids

Question 20

how is closed cs different from open cs

Answer 20

in comparison to open cs, closed cs enable effective delivery of oxygen and nutrients to cells of larger and more active animals due to relatively high BP