Unit1 Module 2 Exchange And Transport Flashcards
What makes a good exchange surface? (3 things)
Large surface area for molecules to pass through
Thin barrier to reduce the diffusion distance
Fresh supply of molecules on one side to maintain a steep diffusion gradient,
Why do multicellular organisms need specialised cell surfaces? (4 bullet points)
Larger the organism, the smaller the surface area to volume ratio,
The cells need more nutrients
The surface is not large enough to deliver nutrients to all of the cells fast enough
Their is a greater distance for the nutrients to travel in order to reach all cells
What happens during inhalation?
Diaphragm contracts Intercostal muscles contract to raise ribs Volume increases Pressure in chest cavity drops Air moves into lungs
What happens during exhalation?
Diaphragm relaxes Intercostal muscles relax so ribs fall Volume decreases Pressure increases Air moves out of lungs
What is the main difference between the structure of trachea/bronchi and the structure of the bronchioles?
The bronchioles have little/no cartilage but the trachea/bronchi have lots of cartilage
Difference between breathing and respiration?
Breathing is the movement of diaphragm that causes air to move in and out of lungs
Respiration is the release of energy in cells
What is tidal volume?
The volume of air moved into/out of lungs at rest
What is vital capacity?
The largest volume of air that can be moved in/out of lungs at rest
Why does the blood pressure in a single circulator system have to be reduced? Why is this okay?
It has to be reduced because fish have tiny capillaries in their gills
This is okay because fish are not as active as mammals and they do not regulate their own body temperature
What is the benefit of a closed circulatory system?
The heart can pump the blood at a higher pressure
What happens during diastole?
Ventricles and atria are both relaxed
The blood flows through the atria, through the open av valves and into ventricles.
What happens during atrial systole?
The atria contract, pushing the blood into the ventricles. As the blood is pushed into the ventricles, the AV valve flaps fill with blood and snap shut.
What happens during ventricular systole?
All 4 heart valves are closed. The ventricles contract, the pressure is raised and the blood is pushed out of of the heart.
Control of the cardiac cycle
The SAN initiates wave of excitement at regular intervals.
It passes over the atria walls, causing them to contract.
It is then delayed at the AVN node.
It is carried away from the AVN node and through the purkyne tissue.
It goes over the ventricle walls, and as it goes upwards from the base it causes the ventricles to contract.
