The Heart Flashcards
Why do larger organisms require a heart?
They have a lower surface area to volume ratio, meaning diffusion alone is not adequate to supply all cells with the necessary nutrients and oxygen.
What is mass transport in terms of the heart?
The bulk movement of blood in one direction; heart contracts creating pressure that moves the transport medium
What are the three types of main types of circulatory systems
- open circulatory systems
- closed double circulatory systems
- closed single circulatory systems
What is an open circulatory system + example ?
- no blood vessels to transport blood
- organs/tissues are directly fed with blood
- in insects heart contracts and blood if so forced out of aorta + into the body; when the heart relaxes blood drawn back via the ostium (small valved openings in the heart) due to change in pressure
What is a closed circulatory system?
- blood is fully enclosed within blood vessels
- ensures higher pressure than open systems = blood can travel further
What is a single closed circulatory system + example ?
- only one contraction to travel blood around the whole body
- travels at lower pressure as high pressure would damage gill capillaries
- in fish —> deoxygenated blood enters heart; goes to gill capillaries to be oxygenated; oxygenated blood moves to systemic capillaries; deoxygenated blood returns to heart
What is double closed circulatory system and the two types?
-heart contracts x2, higher pressures so can travel further
3 chambers
- in amphibians and most reptiles
- 1 ventricle, no septum to separate them
- mixing of O and DO blood is okay due to low metabolic rate
4 chambers
- in birds and mammals
- no mixing of blood due to septum separating pulmonary and systemic, means higher metabolic rate
What are arteries and how are they adapted to their function?
Arteries
- carry blood away from heart at high pressures
- thick muscular walls = withstand blood at high pressure w/o damage
- smooth muscle= contract + relax
- elastic fibres = elastic recoil to maintain pressure
- folded endothelium = allows expansion
- narrow lumen = maintains blood at high pressure
- collagen fibres
What are veins and how are they adapted for their function?
Veins
- carry blood away from tissue/organs and towards the heart
- thinner walls = allow skeletal muscle movement + low blood pressure to draw blood to the heart
- has valves = blood continues to move to heart
- smooth endothelium + large lumen = ensures little resistance in blood flow
- reduced collagen fibres
What are capillaries and how are they adapted to their function?
Capillaries
- gas exchange from blood to tissues
- very thin walls (one cell thick) = reduces diffusion distance; higher rate
- form large network near tissue = increases SA and rate of diffusion
- narrow lumen, (just large enough for one red blood cell) = blood flow slows down allowing time for diffusion
What is the nature of water?
-It is dipole/polar due to the unevenly distribution of charge, slightly negative oxygen (2δ–) and slightly positive hydrogens (δ+)
-Oxygen pulls electrons more strongly
Describe some properties of water
• forms tetrahedral shape (forms up to 4 hydrogen bonds)
• solvent
-due to polar nature can interact with both + and – ions;
- means water molecules can pull away ions in a crystal, dissolving them
= acts as a transport medium, acts as a habitat for aquatic organisms
• Thermal regulator
- high SHC (energy to raise temp of 1kg of water by 1C)
- due to many hydrogen bonds which take energy to break
= stabilising effect on body temp of all organisms; stabilising effect on temperature of large bodies of water as habitats
• Freezing properties
- ice is less dense than water
- bc reducing temp arranges hydrogen bonds in a lattice -> more gaps than in liquid state
= important in habitats - ice floats to the top; act as thermal insulators allowing water below to remain liquid; gives aquatic creatures a home; reflects light energy
• high SLH
- means when we sweat, thermal energy is used up = cooling
• ** Cohesion**
- cohesive, meaning it can move by mass flow
= dissolves substances can be moved by mass flow; allows surface of water to have enough tension allowing it to be a habitat for insects
Describe the stages of the cardiac cycle
Diastole
- blood flows into atria through vena cava + pulmonary vein
- pressure in atria rises, forcing AV valves open, blood enters ventricles
- SL valves closed
Atrial systole
- atria contract —> pushes remaining blood to the ventricles
- ventricular pressure > atrial pressure
- AV valves pushed closed, SL valves also closed
Ventricular systole
- ventricles contract
- higher pressure in ventricles, pushes SL valves open
-both SL + AV valves open
- blood moves from ventricles to arteries
Where are the tricuspid and bicuspid atrioventricular valves?
Tricuspid = right AV valve
Bicuspid = left AV valve
