BIO2242 Lecture Notes - Lecture 10: Extracellular Fluid, Gastrovascular Cavity, Jellyfish
Lecture 10 – Exchange: Circulation
Exchange
• Environment cellular metabolism
o Nutrients
o Respiratory gasses
o Waste products
o Water/salts
o Internal compartment of fluid
Fluid systems and Internal Transport
• Intracellular fluid → interstitial fluid
o Other fluid outside of cells might be divided depending on nature of
organism
o Might just have intracellular and interstitial
o Closed circulatory system: also have blood compartment
• Fish – single tube → heart
• Elephant and budgie – divided heart
• Turtle – slightly divided heart
Very simple thin animals
• Diffusion only without circulatory system
• Direct uptake from environment
• Requires direct contact with medium
• Move the medium (cilia)
• Thickness of tissue layers is limited
Invertebrate transport
• Gastrovascular cavity
• Use water to transport oxygen/nutrients over short distance
o Metabolic rate very low
o E.g. jelly fish
Complex and Large animals
• Circulatory required when diffusion distances are too big
• Comprised of fluid, vessels and pumps
• Open or closed
Closed Circulatory System
Open Circulatory System
• Vertebrates, annelids,
echinoderms
• Blood closed at all times within
vessels
• Blood pumped by heart through
vessels at high velocity
• Haemocoel is absent
• Exchange of materials b/w blood
and tissues take place through
capillaries
• Molluscs and arthropods
(invertebrates)
• Blood flows through open space
very slowly
• Fluid in hemocoel provides
organs with oxygen and nutrients:
combined fluid = haemolymph
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Cephalopod
• Closed circulatory system
• Don’t have blood bathing in haemacill
• Branchial heart → pair of hearts before gills in
order to increase pressure to feed gills
• Single circuit
Annelids
• Closed circulatory system
• Many contractile vessels
Advantages of Closed System
• Can contain more pressure within
set of closed vessels
o Produce greater rates of flow → can move oxygen and nutrients more
rapidly around entire system
o Pressure throughout system is increased
o High pressure
• BUT
o Capillary walls are so thin that lose fluid to outside environment
▪ Fluid leakage to surrounding tissue
o Lymphatic system captures fluid
Vertebrate Circulation
• All closed systems
• Blood about 5-10% of body volume
• Delivery more effective
• Single circuit or double circuit
o Reducing pressure
o Depends on structure of heart
(divisions)
• Systemic circuit – body
• Pulmonary circuit – lungs
Single Circuit Blood Flow
• Found in fish
• 2 chambered heart, one ventricle
• Pressure in gills depends on pressure in rest of body
o Higher pressure – more at risk of fluid leakage
• Volume change with heart contraction
• Disadvantage of single circuit is the pressure in system where gas exchange is
taking place has to be high in order for blood to get around rest of body
• Contraction → heart pumps blood into ventricle → ventricle delivers to rest of
body
• E.g. fish
o Atrium – receives blood from rest of body → pumps into ventricle
o Auxiliary hearts
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Exchange: environment cellular metabolism, nutrients, respiratory gasses, waste products, water/salts, internal compartment of fluid. Very simple thin animals: diffusion only without circulatory system, direct uptake from environment, requires direct contact with medium, move the medium (cilia, thickness of tissue layers is limited. Invertebrate transport: gastrovascular cavity, use water to transport oxygen/nutrients over short distance, metabolic rate very low, e. g. jelly fish. Complex and large animals: circulatory required when diffusion distances are too big, comprised of fluid, vessels and pumps, open or closed. Closed circulatory system: vertebrates, annelids, echinoderms, blood closed at all times within vessels, blood pumped by heart through vessels at high velocity, haemocoel is absent, exchange of materials b/w blood and tissues take place through capillaries. Open circulatory system: molluscs and arthropods (invertebrates, blood flows through open space very slowly, fluid in hemocoel provides organs with oxygen and nutrients: combined fluid = haemolymph.
