Transport in animals Flashcards
What does myogenic mean?
Produce excitations spontaneously, without nerve cell stimulation
What is the order of events that cause a heartbeat?
- Sino-atrial node generates an electrical signal, causing the atria to contract (from the bottom)
- The atrioventricular valve receives the signal and channels it down the bundle of His.
- This signal then spreads through the Purkyne fibres and causes the ventricles to contract.
What do the heart valves do?
Valves prevent blood flowing backwards and only open when the pressure behind the valve from incoming blood exceeds pressure in the ventricle or arteries.
Why is the heart thicker on the left side?
It means that the blood is forced into the atrium under more pressure, thus keeping it travelling quickly.
What are the four mains points of interest in an electrocardiogram?
- The atrioventricular valve closing
- The semilunar valve opening
- The semilunar valve closing
- The AV valve opening
How thick is the muscle layer in the: Arteries Arterioles Capillaries Venules Veins
Arteries : Thick Arterioles : Thickest Capillaries : None Venules : Thin Veins : Thin
How thick is the elastic layer in the: Arteries Arterioles Capillaries Venules Veins
Arteries : Thick Arterioles : Thin Capillaries : None Venules : Thin Veins : Thin
How thick are the following vessels overall: Arteries Arterioles Capillaries Venules Veins
Arteries : Thick Arterioles : Medium Capillaries : 1 cell thick Venules : Thin Veins : Thin
Why do only veins have valves? What also helps this reason?
The valves prevent a backflow of blood due to low pressure. Muscle contraction also helps with this.
Why do arteries have a thick elastic layer?
They can stretch and recoil, allowing them to withstand the high pressure of blood
Why are capillaries so thin?
To maximise rate of diffusion
What components can be found in tissue fluid?
Oxygen Salts Sugars Amino acids Fatty acids Hormones
How does tissue fluid form?
Tissue fluid is a result of two pressures: Hydrostatic and oncotic.
Hydrostatic pressure is due to the contraction of the heart. It pushes the fluid out of the capillaries. It decreases across the tissue fluid.
Oncotic pressure is due to the water potential gradient caused by plasma proteins in the vessels. This means that at the end of the capillary, when oncotic pressure is greater than hydrostatic pressure, water and other substances re-enter the blood stream.
What happens to the tissue fluid that does not re-enter the blood?
It drains into the lymph vessels.
Why is there a delay between atrial and ventricular systole?
To ensure that all blood has been drained from the atriums
Why do animals need specialised transport systems?
- They have high metabolic demands, and so diffusion is not enough to supply the needed quantities
- The SA:Volume ratio gets smaller as multicellular organisms get larger, so not only do diffusion distances get bigger but surface area becomes relatively smaller.
- Molecules such as enzymes may be made in one place but needed in another
- Food will be digested in one organ system, but needs to be transported to every cell to use for respiration and other aspects of cell metabolism.
- Waste products need to be removed from the cells.
What are the three layers of most blood cells and what is between these layers?
Outmost - Tunica externa
Middle - Tunica media
Internal - Tunica intima
There is a lamina layer between each of these layers
What makes up blood?
Red blood cells
White blood cells
Platelets
Blood plasma
What are the steps of oxygen dissassociation?
Carbon dioxide diffuses into erythrocytes and is reacted with water by carbonic anhydrase to form carbonic acid
Carbonic acid dissociates into hydrogen carbonate, which diffuses out of the cells, and hydrogen ions
Negative chloride ions diffuse into the cell to balance the positive hydrogen ions – chloride shift.
The hydrogen ions bind to haemoglobin, producing haemoglobinic acid and causing dissociation of oxygen
How does partial pressure of oxygen effect dissociation?
The higher the partial pressure, the lower the dissociation
