b3.1 (gas exchange) Flashcards
2 examples of when gas exchange sees challenges
organisms become bigger (SA:V decreases)
distance from gas exchange center to extremities increases
what are gills made up of?
gill rakers (thin, flat filaments that are covered with tiny, hair-like structures)
what is notable about the respiratory system in salamanders?
as they live in different environments throughout their life cycle, they have gills as larva (as they spend more time in water) as lungs develop for their adult life (as they spend more time on land)
define neotenic. how is this seen in axolotls?
when an organism retains their juvenile features throughout their entire lives
axolotls retain their external gills whereas in many other amphibians, gills are typically lost after metamorphosis
define the common name and function of the trachea
windpipe
carries air from the mouth and nose to the lungs
what does the trachea divide into? what does this further branch into?
two bronchi (plural of bronchus), which further branch into smaller bronchioles within the lungs
what sits at the end of bronchioles?
tiny air sacs called alveoli, which are the primary site of gas exchange
what is the pleura? what are its two parts?
a double-layered membrane surrounding the lungs
visceral pleura: inner layer that directly covers the lungs, including the fissures
parietal pleura: outer layer that lines the chest wall, diaphragm, and mediastinum (the space between the lungs)
what is the mediastinum?
the space between the lungs
what thin space between the pleura layers helps reduce friction? how?
what else does this space assist with?
the pleural cavity
contains a small amount of pleural fluid that reduces friction during breathing
assist in lung expansion and contraction during respiration
what are alveoli surrounded by? how does this cause gas exchange?
what does the flow of O₂ and CO₂ look like?
a dense network of capillaries
gas exchange occurs through simple diffusion due to differences in gas concentrations between the air in the alveoli and the blood in the capillaries. the thin wall of the alveoli is essential for this
inhaled O₂ diffuses through alveoli walls into blood
CO₂ from blood diffuses into the alveoli to be exhaled
what is a pneumocyte?
an epithelial cell that forms the main constituent of the lining of the air side of the pulmonary alveolus
what do type 2 pneumocytes produce? what does it do?
surfactant (a phospholipid/protein based film). reduces surface tension (H-bonds) in moisture lining the alveoli, which prevents each alveolus from collapsing on itself
what is an epithelial cell?
cells that make up skin surface & lines cavities, glands and passages in the body
what do type 1 pneumocytes do?
to ensure gas exchanges between the organism and its environment (passive and active diffusion of oxygen and carbon dioxide)
how does inhalation occur? x3 steps of movement
the diaphragm contracts and moves downward
intercostal muscles between the ribs contract
chest cavity is expanded and draws air into the lungs
is exhalation usually passive or active? justify
usually passive, with the diaphragm and intercostal muscles relaxing, causing the chest cavity to decrease in size and expel air
what does boyle’s law state? how does this relate to respiration?
pressure is inversely proportional to volume (P × V = constant)
as volume increases during inhalation, pressure decreases and air flows in
as volume decreases during exhalation, pressure increases and air flows out
what is tidal volume (TV)? how can it be measured x3?
the amount of air you breathe in and out when you’re resting
spirometer, body plethysmography, or a measuring tape
define inspiratory reserve
the additional amount of air you can forcefully inhale beyond a normal breath
define expiratory reserve
the extra air you can forcefully exhale after a normal exhalation; beyond a typical tidal volume
define hemoglobin. what are its 2 main functions?
an iron-rich protein in red blood cells
carries oxygen throughout the body
removes carbon dioxide from tissues and organs
define heme. how does it relate to hemoglobin structure?
an iron-containing compound of theporphyrinclass which forms the nonprotein part ofhemoglobinand some other biological molecules
each of the 4 hemoglobin subunits carries one molecule of heme
look online at how heme is bonded
-
hemoglobin’s binding of oxygen is cooperative. what does this mean?
what does it enable?
increased binding affinity (the strength of the binding interaction between a single biomolecule to its binding partner) as more oxygen molecules bind into binding sites
binding allows hemoglobin to transport more oxygen to tissues that need it most
look at an oxygen-hemoglobin dissociation curve
-
during pregnancy, oxygen dissociates from hemoglobin in maternal blood in the placenta and binds to haemoglobin in fetal blood.
why does this occur?
fetal hemoglobin has a stronger affinity for oxygen than adult hemoglobin
look at slide 30 b3.1 (bohr shift)
-
watch a video on how leaves breathe
-
know how to draw leaf tissues (diagram on slide 35 b3.1)
-
how do the following factors affect transpiration?: (more/less & how)
air movement
humidity
light intensity
temperature
air movement: more, removes H2O vapour from nearby air, creating a concentration gradient and increasing water loss
humidity: less, with more H2O vapour in the air, a weaker concentration gradient causes less H2O loss
light intensity: more, guard cells are responsive to it; high = turgid, & stomata open allowing H2O loss
temperature: more, particles have more KE so transpiration & evaporation-diffusion occurs faster
equation for stomatal density (mm⁻²)
(mean number of stomata) / (area of field of view)
technique used to determine stomatal density x3 steps
- a sample of epidermis is peeled off the leaf
- colourless nail varnish is painted on small areas of epidermis. varnish forms a cast of the leaf surface with stomata visible
- when dry, it is peeled off, mounted on a microscope slide and examined
how does low pressure (such as in the atmosphere) affect transpiration?
forces water to be drawn out of the leaves
