Mass Transport
Example:
02 February 2024 11:43
Why do small animals have a heart and circulatory system?
Need for a circulatory system:
• In order to survive, Animals require essential substances (Oxygen, CO2...) to enter and leave the
body
• Small organisms can rely on diffusion alone due to larger SFA:V ratio
• As the organism increases in size, SFA:V ratio decreases, diffusion distance increases and
greater metabolic rate
• Diffusion alone is too slow so mass transport system is required (heart, vessels...)
Features of a mass transport system:
• Vessels
• Directional
• Transport medium (water):
Water:
• Polar (has a dipole)
• Forms hydrogen bonds
• High latent heat of vaporisation, hydrogen bonds are strong and hard to break
(require lots of heat)
Why water is the ideal transport medium:
• High specific heat capacity: Blood helps regulate body temperature because it
resists temperature changes (water is slow to heat or cool)
• Good solvent: Dissolves ionic substances (by surrounding them), easily dissolves
because it's polar
• Liquid at room temperature: It can flow (cohesion between molecules)
Example:
How do the properties of water make it an ideal transport medium?
Topic 1 página 1
,Cardiovascular System Example:
05 February 2024 11:49
Explain how the structure of an artery relates to its function:
Blood Vessels
Functions:
• Endothelium: One cell thick, smooth to reduce friction (folded)
• Smooth Muscle: Contract and relax to accommodate blood volumes
• Elastic fibres: Stretch and recoil to maintain pressure
• Collagen: Provides strength/flexibility and prevents rupture
Relating structure of vessels to their functions:
Artery:
• Folded smooth endothelium to reduce friction Example:
• Collagen to prevent it from rupture/bursting
• Narrow lumen to maintain high blood pressure Explain how the structure of an artery wall is adapted both to withstand and to maintain high blood
• Elastic fibres recoil to maintain pressure pressure:
Vein:
• Valves to prevent backflow
• Larger lumen to minimise resistance
• Less muscle, elastic fibres and collagen
Capillary:
• Once cell thick walls to minimise diffusion distance
• Very small so they can reach all cells
The Heart
Cardiac Cycle:
Atrial Systole:
• Walls of atria contract
• Ventricles remain relaxed
Ventricular Systole:
Topic 1 página 2
,Ventricular Systole:
• Atria relax
• Ventricles contract
Cardiac Diastole:
• Ventricles relax
• Atria relax
Example question on pressure changes:
Topic 1 página 3
, Topic 1 página 4
Example:
02 February 2024 11:43
Why do small animals have a heart and circulatory system?
Need for a circulatory system:
• In order to survive, Animals require essential substances (Oxygen, CO2...) to enter and leave the
body
• Small organisms can rely on diffusion alone due to larger SFA:V ratio
• As the organism increases in size, SFA:V ratio decreases, diffusion distance increases and
greater metabolic rate
• Diffusion alone is too slow so mass transport system is required (heart, vessels...)
Features of a mass transport system:
• Vessels
• Directional
• Transport medium (water):
Water:
• Polar (has a dipole)
• Forms hydrogen bonds
• High latent heat of vaporisation, hydrogen bonds are strong and hard to break
(require lots of heat)
Why water is the ideal transport medium:
• High specific heat capacity: Blood helps regulate body temperature because it
resists temperature changes (water is slow to heat or cool)
• Good solvent: Dissolves ionic substances (by surrounding them), easily dissolves
because it's polar
• Liquid at room temperature: It can flow (cohesion between molecules)
Example:
How do the properties of water make it an ideal transport medium?
Topic 1 página 1
,Cardiovascular System Example:
05 February 2024 11:49
Explain how the structure of an artery relates to its function:
Blood Vessels
Functions:
• Endothelium: One cell thick, smooth to reduce friction (folded)
• Smooth Muscle: Contract and relax to accommodate blood volumes
• Elastic fibres: Stretch and recoil to maintain pressure
• Collagen: Provides strength/flexibility and prevents rupture
Relating structure of vessels to their functions:
Artery:
• Folded smooth endothelium to reduce friction Example:
• Collagen to prevent it from rupture/bursting
• Narrow lumen to maintain high blood pressure Explain how the structure of an artery wall is adapted both to withstand and to maintain high blood
• Elastic fibres recoil to maintain pressure pressure:
Vein:
• Valves to prevent backflow
• Larger lumen to minimise resistance
• Less muscle, elastic fibres and collagen
Capillary:
• Once cell thick walls to minimise diffusion distance
• Very small so they can reach all cells
The Heart
Cardiac Cycle:
Atrial Systole:
• Walls of atria contract
• Ventricles remain relaxed
Ventricular Systole:
Topic 1 página 2
,Ventricular Systole:
• Atria relax
• Ventricles contract
Cardiac Diastole:
• Ventricles relax
• Atria relax
Example question on pressure changes:
Topic 1 página 3
, Topic 1 página 4
