Exchange And Transport Flashcards
Structure of the waxy cuticle of the leaf?
Waterproof to reduce evaporation of water
Transparent to allow light through
Structure of the upper epidermis of the leaf?
Thin (only one layer) and transparent to allow light through
Structure of palisade cells in the leaf?
Many chloroplasts packed tightly at the top of the leaf
Structure of the vein of the leaf?
Contains xylem and phloem
Structure of lower epidermis of the leaf?
Contains guard cells which open and close the stomata to allow gas exchange
Structure of spongy mesophyll cells in the leaf?
Irregular shaped cells with large surface area with air spaces between to allow gases to reach all cells
Structure and function of plant root?
Absorbs water and minerals
Lots of root hair cells to increase surface area
Osmosis definition?
The diffusion of water molecules from an area of high water potential to an area of low water potential through a partially permeable membrane
Equilibrium definition in regards to osmosis?
Equal movement of water molecules in both direction, so no net movement
Water potential definition?
The pressure exerted by water molecules that are free to move in a system and so their tendency to move by osmosis
What is the kPa of pure water?
0, the highest possible water potential
What does water in the root need to go through to get the the xylem?
Epidermis, cortex, endodermis
Two water pathways in roots?
Apoplast and symplast
What does the apoplast pathway consist of?
Everything external to the plasma membrane of the living cells (cell walls and air spaces)
What does the symplast pathway consist of?
Cytosol and plasmodesmata
Through cell membranes
What is the casparian strip?
A waterproof strip in the endodermis made of Suberin. Blocks the apoplast pathway
How does water move past the casparian strip?
Moves inside the cells
How does water finally get into the xylem?
Water follows the lower water potential in the xylem to dilute it from the minerals
Structure of the xylem?
Cell walls contain lignin which is waterproof so cells die
End cell walls and cell contents decay creating a thin continuous tube
Lignin keeps the xylem strengthened
Function of bordered pits in xylem?
Lets water out of xylem sideways if needed
How does water move up the xylem?
Tension- as water evaporates from the leaf through the stomata the water in the leaf cell must be replaced from the xylem (transpiration pull)
Cohesion- water molecules are polar and attracted to each other forming hydrogen bonds allowing a continuous column of water
Adhesion- water molecules bond to sides of xylem which helps pull water up the stem as gravity is reduced
Root pressure- active transport of minerals into xylem water follows by osmosis. This pressure forces water upwards
Transpiration meaning?
Movement of water out of leaves
Guard cell function?
Controls water leaving the plant. Open and closes stomata by swelling when turgid
Transpiration process?
ATP used to transport potassium ions into guard cells lowing water potential
Water moves in by osmosis
Guard cells swell and open stomata
Factors affecting transpiration?
Stomata being open in response to light and low co2 levels
Stomata closing in response to drought
Temperature, high increase evaporation from stomata
Wind speed, wind blows water vapour away lowing water potential in surrounding air
Humidity, water vapour will increase in surrounding air so water will not diffuse out
What is a xerophyte?
A species of plant that is designed to deal with very little water
How are xerophytes adapted?
Rolled leaves to trap air, increasing humid and water potential in surround air
Extremely thick waxy cuticle
Reduced number of stomata
Stomata are in sunken pits reducing air movement
Lower epidermis have tiny hairs (trichomes) to trap moisture
Densely packed mesophyll so smaller surface area for evaporation
Leaf cells may have high salt concentration so lower water potential
Root system is deeper
The role of the mouth/nose in gaseous exchange?
Air enters through nose and mouth
Air filter by nose hairs and mucus to trap dust/bacteria
Air is warmed and humidified to match air in the lungs
The role of the pharynx in gaseous exchange?
Air enters, it’s an intersection where paths for oesophagus and trachea cross
The role of the larynx in gaseous exchange?
Closes during swallowing so food does not enter the trachea
The role of the trachea in gaseous exchange?
Supported by c-shaped rings of strong, flexible cartilage to prevent it collapsing
The role of the bronchi in gaseous exchange?
Both right and left lead to the lungs
Narrower than trachea
Supported by rings of cartilage
The role of the bronchioles in gaseous exchange?
Numerous narrow branches that divide away from bronchi
No cartilage
Walls contain smooth muscle and elastic fibre that contract and relax to regulate air flow to the lungs
The role of the ciliated epithelial cells in gaseous exchange?
Line the trachea, bronchi and bronchioles
Waft to move mucus upwards away from lungs
Contain many mitochondria
The role of the goblet cells in gaseous exchange?
Secrete mucus onto epithelial lining to trap dust/bacteria
The role of the alveoli in gaseous exchange?
Tiny air sacs
Increase surface area for gas exchange
Covered by capillaries
How to work out surface area?
Area x number of sides
How to work out volume?
Length x width x height
What is Fick’s law?
Diffusion rate= surface area x conc. diff
————————————
Distance
How are alveoli adapted in terms of concentration?
Good blood supply, lots of capillaries maintain steep concentration gradient
Constant ventilation also maintains steep concentration gradient
How are alveoli adapted in terms of distance?
Wall of alveolus is one cell thick
Wall of capillary is one cell thick
Extracellular matrix contains collagen for support and elastin to allow for stretching and recoil
How are alveoli adapted in terms of surface area?
Moist surface area for oxygen to dissolve and diffuse rapidly
Type 2 alveolar cells secrete surfactant , reduce surface tension so alveolar don’t collapse
There basic ways alveoli are adapted?
Surface area
Concentration
Distance
Features of cardiac muscle?
Never tires
Myogenic (contracts involuntarily)
Required a large energy supply
What valve separates the right ventricle and left ventricle?
Tricuspid
What valve separates the right ventricle and pulmonary artery?
Pulmonary
What valve separates the left ventricle and the aorta?
Aortic
What valve separates the left atrium and left ventricle?
Bicuspid (mitral)
How does blood enter the right atrium?
The superior and inferior vena cava
Basic blood flow sequence?
Vena cava Right atrium Right ventricle Pulmonary artery Lungs Pulmonary veins Left atrium Left ventricle Aorta Rest of body
Equation for aerobic respiration?
Glucose + oxygen —> carbon dioxide and water
What supplies the cardiac muscle with oxygen and glucose and removes waste co2?
Coronary arteries
Name of atrioventricular valves?
Tricuspid
Bicuspid (mitral)
Name of semilunar valves?
Pulmonary
Aortic
Cardiac cycle sequence?
Atrial systole
Ventricular systole
Diastole
Atrial systole process?
Atria contract
Semi-lunar valves closed
Atrioventricular valves open
Blood forces from ventricles to atria to ventricles
Ventricular systole process?
Ventricles contract Atria relax Semilunar valves open Atrioventricular valves close Blood is forced into arteries
Diastole process?
Semilunar valves close due to pressure of blood in arteries
Atria and ventricles relax and fill with blood from the veins
Atrioventricular valves open, pressure is higher in atria then ventricles
Where is the sinoatrial node found?
Right atrium
Sinoatrial node function?
Can generate and send on a wave of depolarisation and spreads across the atria causing contraction until it reaches the atrioventricular node
Where is the atrioventricular node found?
Bottom of right atrium
Atrioventricular node function?
Caused a slight delay to allow ventricles to fill properly
Where is the bundle of his found?
In the middle between right and left chambers
Where is the perkinje fibre found?
Bottom of ventricles
Purkinje fibre function?
Carries message to ventricles cause them to contract so blood flows out into pulmonary artery
Order of cardiac coordination?
SAN
AVN
Bundle of his
Perkinje fibres
P wave?
Wave of depolarisation spreads over atria from sinoatrial node causing contraction of atria
(First small peak)
PR interval?
Time taken for wave of depolarisation to reach ventricles
Measured from start of P wave to start of QRS complex
What causes first ECG flatline?
Delay at AVN
QRS complex?
Wave of depolarisation spreads across both ventricles causing ventricular systole
ST segment?
Flat line between end of QRS and T
Gap between end of ventricular depolarisation and repolarisation
T wave?
Repolarisation of ventricles - diastole
What do 5 big squares on an ECG represent?
1 second
What does the vena cavae do?
Veins that bring deoxygenated blood back from the body
What does the aorta do?
An artery that carries oxygenated blood to the rest of the body
What do the pulmonary arteries do?
Take deoxygenated blood to the lungs to be oxygenated
What do the pulmonary veins do?
Return oxygenated blood from the lungs to the heart
Basic cardiac cycle order?
Wave of excitation spreads from SAN across atria
Atria contract and pump blood into ventricles
Wave reaches the AVN and is delayed
Wave transmitted along Purkinje fibres to ventricles
Ventricles contract and pump blood into arteries
Atria and ventricles relax
Atria fills with blood from vena cavae and pulmonary veins
