Topic 1 - The Heart (+Water) (1.1 to 1.4) Flashcards
What is a mass transport system
A system which transports substances (such as oxygen) from one part of an organism in one direction via vessels or tubes
Why are mass transport systems used
They overcome limits of diffusion → making transport in an organism more efficient
Larger organisms need mass transport systems as their small Sa:V is low, so the rate of diffusion is low
By having a mass transport system molecules such as glucose can diffuse into cells faster
How does having a mass transport system affect metabolic rate
It ensures a high metabolic rate as mammals have a high demand for glucose and oxygen
A mass transport system helps make the diffusion of these molecules more efficient
What type of system is the circulatory system
It is a mass transport system
What are the features of an efficient circulatory system (4 features)
- Pump
- Transport medium
- Blood vessels
- Exchange surfaces
Why are different blood pressures needed in a circulatory system
Different pressures are needed for different process / reactions in the body
+ So that the blood can be transported (mass flow)
Why do exchange surfaces like capillaries make the circulatiry system more efficient
They have a high SA:V ratio making diffusion more efficient
What are the features of an open circulatory system
No vessels to transport blood
Blood (Haemolymph in insects) is pumped into body cavities
Haemolymph has direct contact to cells / tissue for nutrient exchange
(Short diffusion distance between the heart and cavities)
(Heamolymph carries mineral ions and hormones)
Low blood pressure (no vessels to maintain a pressure gradient)
Why do smaller organisms have open circulatory systems
Small organisms have a low metabolic demand so efficient transport is not required
They have a large Sa : V so diffusion can be effective
What are the features of a closed circulatory systen
They have blood enclosed in vessels
This maintains a high blood pressure, so blood flows faster
This enables a higher metabolic rate (as o2 and glucose can be transported to cells faster)
Why do mamals have a high metabolic rate
Mamals have a large number of cells, so they have a greater requirement for energy
What vessels does blood pass through when going around the body (not a specific artery / veins)
Heart → arteries (aorta) → arterioles → capillaries → venules →veins → heart
What are the properties / blood flow in a 3-chambered heart
Oxygenated and deoxygenated blood enter into two different chambers and then mix together in the third chamber
Blood is taken to the lungs in the 3rd chamber, oxygenated and put back into the 2nd chamber.
The oxygenated blood enters the 3rd chamber and is taken to the rest of the body
What are ectotherms
Organisms that rely their environment to regulate body temperature
They have lower metabolic demands as they dont regulate their body temperature
What are the main features of a single circulatory system
Blood flows through the heart once per each full circuit of the body
2 chambered heart
Gill exchange network (deoxygenated blood going to gills) e.g fish
Systemic circuit ( blood going to body)
What are the main features of a double circulatory system
Blood flows through the heart twice for each full complete circuit of the body
4- chambered heart to ensure blood is pumped to the rest of the body at a high pressure
Pulmonary circuit - blood to lungs + back to heart
Systemic circuitb- supplies oxygenated blood to all the metabollic cells
How much of blood plasma is made of water
90%
What is a polar molecule
A molecule with unevenly distributed charges (it is dipole)
Water is a polar molecule
What is cohesion
Molecules forming bonds with similar molecules
How is water cohesive
Water forms hydrogen bonds to other water molecules
This allows water to flow (which makes it useful
Water can bond to up to 4 other water molecules
How is water a solvent
It is able to surround polar molecules and ions
It forms hydrogen bonds with the ions letting them be dissolved and transported
How is water a thermal buffer
It has a high specific hera capacity (lots of energy needed to change its temp)
It has a high latent heat of vaporisation (lots of heat needed to break bonds)
→ vaporised water carries heat away from the body
What is the heart made of
Cardiac muscle
How does the heart ‘beat’
Myogenic - It can move without instructions from the brain
Cardiac muscle can contract and relax via some input from the nervous system