gas exchange 2

how do the xylem and phlegm in the leaf help with gas exchange

-help maintain the concentration gradient
-the xylem supplies water to the lead maintaining a high concentration in the leaf
-the phloem removes sucrose maintaining a low concentration in the leaf

adaptions for alveoli for gas exchange

-has a layer of water so gases can dissolve easily
-have a ventilation mechanism and a circulatory system to circulate the blood so that concentration gradients are maintained
-made of squamous epithelial cells so diffusion distance is short
-contains surfactant that reduces surface tension so the alveoli dont collapse on exhalation so sa remains high

how doe volume in the lungs increase

-ribs move upwards and outwards
-pleural membranes are pulled upwards and outwards
-diaphragm moves down and lowers

why is inhalation an active process

because ATP is needed to contract the muscles in the diaphragm and intercostal muscles

function of the pleural membrane

-airtight layer around the lungs to ensure air stays in the lungs
-secrete pleural fluid to reduce friction when the pleural membrane move
-protect alveoli from the ribs

where is the diaphragm found

separating the thorax and the abdomen

why is exhalation an active process

-muscles are relaxing not contracting and therefore no ATP is required

why does air move from the environment to the alveoli

because alveoli have a negative pressure so air moves down the pressure gradient

how does a guard cell form a stomata

-potassium ions are actively transported to the guard cell
-malate ions are produced from insoluble starch in the guard cell
-potassium and malate ions reduce water potential of guard cell
-water moves by osmosis into the guard cell from the lower epidermal cells down the water potential gradient
-this makes the guard cells turgid
-due to the outer wall being thinner the side bends more forming a pore between two guard cells

name the gas exchange surface in humans

alveoli

how can the bronchioles control the air flow to the alveoli

by contracting or relaxing the muscles around them

what gases are exchanged when a stomata is open

-oxygen and carbon dioxide will diffuse out of the leaf
-carbon dioxide will diffuse into the leaf

why are the trachea surrounded by C shaped rings of cartilage

-it is required to prevent the trachea collapsing under negative pressure
-the rings are C shaped so that the trachea is flexible enough to allow food to pass down he oesophagus

how are the guard cells adapted for gas exchange

-they can become turgid or flaccid to allow formation of stoma
-if they are turgid there is a stoma and gas exchange can occur

apart from the trachea, which other structure of the respiratory system contains rings of cartilage

bronchus

how is the spongy mesophyll layer adapted for gas exchange

-it contains air spaces to allow space to shorten the diffusion distance for gases
-additionally they are permeable allowing gas to exchange between the air spaces and the cells

how is the cuticle of a leaf adapted for gas exchange

it is impermeable to prevent water loss