Chapter 7- Mass transport Flashcards
What is haemoglobin
a group of chemically similar molecules found in a wide variety of organisms
Structure of haemoglobin
- primary structure is the sequence of AA’s in the 4 polypeptide chains
- secondary structure in which polypeptide chains coil into a helix
- tertiary structure where polypeptide chains fold into a precise shape
- quaternary structure where all 4 polypeptide chains are linked together to form an almost spherical molecule
What is loading/association
process by which haemoglobin binds with oxygen
What is unloading/dissociation
process by which haemoglobin releases its oxygen
what are some properties haemoglobin must have to efficiently transport oxygen
- be able to readily associate with oxygen
- readily dissociate from oxygen
What is an oxygen dissociation curve
- s shaped curve
- shows a relationship between the saturation of haemoglobin with oxygen and the partial pressure of oxygen
Describe the shape of the first part of an oxygen dissociation curve
- slow increase to begin as its difficult for oxygen to bind
Describe the shape of the second part of the oxygen dissociation curve
- its easier for oxygen to bind as after the first oxygen binded, it changed the quaternary structure of the haemoglobin
- results in a steeper angle of the curve
Describe the shape of the third part of an oxygen dissociation curve
- -the curve starts to flatten out as there is only a smaller increase in partial pressure because there is becoming less area for the oxygen to bind to
How does carbon dioxide effect haemoglobin
CO2 reduces affinity for oxygen
Describe the structure of the heart
- two pumps
- left pump deals with oxygenated blood
- right pump deals with deoxygenated blood
- both sides have an atrium which is a thin- walled and elastic and stretches as it collects blood
- both sides have ventricles which are thicker muscular walls as it has to contract strongly to pump blood
What are the valves called and what are they used for
- two valves
- left atrioventricular (bicuspid) valve
- right atrioventricular ( tricuspid) valve
- the use is to prevent backflow of blood
What are the two stages of the cardiac cycle
- contraction ( systole)
- relaxation (diastole)
Describe diastole
- blood returns to the atria of the heart through the pulmonary vein (from the lungs) and the vena cava (from the body)
- blood flows into the ventricles when the pressure gets higher making the atrioventricular valves to open
Describe atrial systole
- contraction of atrial walls force remaining blood in the atria to move into the ventricle
Describe ventricular systole
- contraction of ventricular walls which causes blood to be pumped to the lungs and the rest of the body
What are the atrioventricular valves
- valves between the atrium and ventricles on both sides of the heart
- prevent backflow of blood into atrium when ventricles contract
What are the semi-lunar valves
- in the aorta and pulmonary artery
- prevents backflow of blood into ventricles when blood is pumped from the ventricles
What are the pocket valves
- valves throughout the venous system
- ensures veins are squeezed to move blood in only one direction
What is cardiac output and what is the equation
- cardiac output is the volume of blood pumped by one ventricle in one minute
- cardiac output = heart rate x stroke volume
What are the four blood vessels
- arteries- carry blood away from heart to arterioles
- arterioles- small arteries that control blood flow from arteries to capillaries
- capillaries- tiny vessels that link arterioles to veins
- veins- carry blood from capillaries back to the heart
What are common structural features in arteries, arterioles and veins
- tough fibrous outer layer- resists pressure changes
- muscle layer- contract so control the flow of blood
- elastic layer- helps to maintain blood pressure by stretching and recoiling
- thin inner lining- smooth to reduce friction
- lumen- center cavity which the blood flows
What is the process of transpiration
- the evaporation of water from leaves of a plant
How is water moved up the xylem
- cohesion-tension - as water evaporates, new water replaces to maintain a water potential gradient
What is translocation
- the process by which organic molecules and some mineral ions are transported from one part of a plant to another
Where does a plant moves sugars produced in photosynthesis
- from the sources (site of production), they are stored in sinks for direct use or future use
How can the mass flow theory be broken down into
- transfer of sucrose into sieve elements from photosynthesis tissue
- mass flow of sucrose through sieve tube elements
- transfer of sucrose from the sieve tube elements into storage or other sink cells
look on page 188
What are ringing experiments
- a section of the outer layer is removed around the circumference of a woody stem
- the region immediately above will swell because of an accumulation of sugars
What are tracer experiments
- radioactive isotopes can track the amount of CO2 in plants by the isotope 14C
- the radioactive sugars can be tracked throughout the plant by autoradiography
what theory follows the mechanism of translocation
mass flow theory
1. transfer of sucrose into sieve elements from photosynthesis tissue
2. mass flow of sucrose through sieve tube elements
3. transfer of sucrose from the sieve tube elements into storage or other sink cells
How is water moved out by the stomata
- higher humidity in the atmosphere than the stomata
- resulting in a water potential gradient from the air spaces through the stomata to the air
- if stomata are open, water diffuses out of the air spaces into the air
How does water move across cells in a leaf
- mesophyll cells lose water to air spaces by evaporation due to heat by the sun
- the cells now have a lower water potential so water enters by osmosis
- loss of water from neighbouring cells lowers their water potential
- they in turn take water from other neighbouring cells by osmosis
