3.2.1 transport in animals Flashcards
double circulatory system
blood flows through heart twice for each circuit of the body
single circulatory system
blood flows through heart once for each circuit of body
transport
movement of substances eg. oxygen, nutrients, hormones
why do small animals not need a separate transport system
- all cells surrounded/close to environment they live in
- diffusion supplies enough oxygen/nutrients
what are the 3 main factors that influence the need for a transport system
- size
- surface area to volume ratio
- level of metabolic activity
why does size influence the need for a transport system
- cells inside a large organism are further from surface = diffusion pathway is increased
- diffusion rate reduced & diffusion to slow to supply requirements
- outer layers of cells use up supplies so less will reach cells deep inside body
why does SA:Vol influence the need for a transport system
- larger animals have smaller SA:Vol = each gram of tissue has smaller area of body surface for exchange
why does the level of metabolic activity influence the need for a transport system
- animals require energy from food
- releasing energy from food via aerobic respiration needs oxygen
- if animal’s active, it’s cells need good supplies of nutrients/oxygen (for energy)
- animals that keep themselves warm (eg. mammals) require more energy
features of a good/effective transport system
- fluid/medium = carry nutrients, oxygen/waste around body
- pump = creates pressure to push fluid around body
- exchange surfaces = enable substances to enter/leave blood where needed
what’s the fluid/medium, pump & exchange surfaces within our body
fluid/medium = blood
pump = heart
exchange surfaces = capillaries
what does as efficient transport system also include
- tubes/vessels to carry blood by mass flow
- 2 circuits = 1 to pick up oxygen & 1 to deliver oxygen to tissues
which animal example has a double circulatory system
mammals (2 separate circuits)
1 circuit = carries blood to lungs - pick up oxygen (pulmonary circulation)
2 circuit = carries oxygen/nutrients around body to tissues (systemic circulation)
heart –> body –> heart –> lungs –> heart
which animal example has a single circulatory system
fish
heart –> gills –> body –> heart
features of a fish’s single circulatory system
- blood pressure drops as blood passes through tiny capillaries in gills
- blood has low pressure as flow to body = not flow quickly
- rate oxygen/nutrients are delivered to respiring tissues (& CO2/urea removed) = limited
features of a mammal’s double circulatory system
- blood pressure must not be too high (pulmonary circulation) as may damage capillaries in lungs
- heart can increase pressure of blood after passed through lungs = blood under higher pressure as flows to body & more quickly
- systemic circulation carries blood at higher pressure
why do mammals need more energy, what is this energy used for & where does it come from
need:
- active animals
- maintain body temp.
used:
- supply energy for activity
- energy for heat need to keep body warm –> needs energy from food
from:
- released from food in process of respiration
- cells need good supply of both nutrients/oxygen to release lots of energy (& rid of waste products)
