C8 - Transport in animals Flashcards
Why do some organisms require a specialised transport system?
-High metabolic demands so diffusion is insufficient
-Small SA:V ratio
-Molecules made in one place but required in another
What features do circulatory systems have in common?
-Liquid transport medium that circulates
-Vessels to carry transport system
-Pumping mechanism to move fluid
(-Valves)
What is a circulatory system?
Transport system of an animal
What is a mass transport system
Transport system where substances are transported in a mass of fluid
What is an open circulatory system?
Circulatory system with a heart but few vessels to contain the transport medium
Describe the circulation in an open circulatory system?
Transport medium pumped from heart to body cavity (haemocoel)
Under low pressure in haemocoel and in direct contact with cells and tissues enabling exchange
Transport medium returns to heart
Which animals have open circulatory systems?
Invertebrate animals
What is a closed circulatory system?
Circulatory system where blood is enclosed in blood vessels and does not come in direct contact with cells of the body beyond blood vessels
Which animals have closed circulatory systems?
Vertebrate
What is a single closed circulatory system?
Circulatory system where blood flows through the heart and is pumped out to travel around the body before returning
What is a double closed circulatory system?
Circulatory system where blood travels twice through the heart for each complete circulation of the body
How do nutrients in blood reach cells in a single closed circulatory system?
Passes through two sets of capillaries
1st set- exchanges O2 and CO2
2nd set- substances exchanged between capillaries and cells
What are the cons to a single closed circulatory system?
BP drops due to passing through two sets of capillaries
Blood returns to heart slowly
How do nutrients in blood reach cells in a single closed circulatory system?
Blood pumped form hearts to lungs to exchange O2 and CO2 and then returns to heaty
Blood flows through heart and is pumped to rest of body before returning to heart
What are the positives to a double closed circulatory system?
Only passes through one set of capillaries
High pressure blood allows fast blood flow to heart and body
What are the three different components in blood vessels?
-Elastin fibres: can stretch/recoil providing flexibility
-Smooth muscle: contracts/relaxes with change in lumen size
-Collagen: provides structural support maintaining shape and volume
What blood do arteries carry?
High pressure oxygenated blood
EXCEPT for pulmonary artery and umbilical artery
Describe the structure of arteries
Walls contain thick layer of elastic fibres, smooth muscle and collagen
Smooth lining (endothelium)
Small lumen
What is the role of elastic fibres?
-Enables arteries to withstand force of blood being pumped
-Enables arteries to stretch to take larger blood volume
-In between pumps of heart, elastic fibres recoil, helps even out surges of blood to give continuous flow
What does the smooth lining enable?
Blood flows easily over it
What is the role of arterioles?
Link arteries to capillaries
Structure of arterioles compared to arteries?
More smooth muscle and less elastin in walls as they have little pulse surge
Can constrict/dilate
What is vasoconstriction?
Smooth muscle wall of arteriole constricts decreasing blood flow through capillaries
What is vasodilation?
Smooth muscle wall of arteriole relaxes increasing blood flow through capillaries
What are capillaries
Microscopic blood vessels linking arterioles with venules
Describe structure of capillary
Very small lumen (fits singular RBC)
Capillary wall made of endothelial cells
Gaps between cells are relatively large
How are capillaries adapted for their role?
-Large SA for diffusion
-Total cross sectional area of capillary is greater than artery allowing BP to fall, to increase time for diffusion
-Walls are single endothelial cell thick so short diffusion distance
What blood do veins carry?
Low pressure deoxygenated blood
EXCEPT pulmonary vein and umbilical vein
Describe the structure of veins
-Thin walls containing lots of collagen, smuscle and little elastic fibre
-Wide lumen and smooth endothelium lining so blood flows easy
-Valves
Compare structure of venules to veins
Very thin walls with just smooth muscle
How are veins adapted to overcome prevent backflow
-Have one way valves at intervals: flaps/infoldings of inner lining, valves close if blood flows backwards
-Valves prevent backflow when muscles relax
-Breathing movements act like pump
What is blood consist of?
Yellow liquid, plasma, which contains many substances dissolved
What are the functions of blood
Transport of:
O2
CO2
Digested food from small intestine
Nitrogenous waste products to excretory organs
Food molecules
Platelets
Cells and antibodies
-Maintenance of steady body temperature
-Buffer: minimising pH changes
What is tissue fluid?
Solution surrounding the cells of multicellular animals