quiz 7 Flashcards
complex functions of single-celled organisms
- locomotion
- feeding
- decision making
- sensing (i.e. harpoons that detect nearby organisms and stab them)
common problems with the physiology of multicellular organisms (that are not problems for unicellular organisms)
- gas exchange
- nutrient/waste delivery
- water balance
- central control processing (internal homeostatic, motor control, external sensory stimuli)
materials needed to diffuse in/out of cells
- oxygen in
- CO2 out
- nutrients in
- waste out
*easy to diffuse with single cells, challenging with layers
rate of diffusion
about 100 micrometers every 2.5 seconds
diffusion in water vs air
- diffusion much slower in water/fluid
- explains why pneumonia or covid causes trouble getting enough oxygen, fluid in alveoli
how does diffusion impact metabolic rate
- metabolic rate can be stressed by a greater diffusion distance, as diffusion takes time (materials take longer to enter/exit cells)
basal and functional metabolic rates
- basal metabolic rate is consistent among organisms, both unicellular and multicellular
- functional metabolic rate changes depending on movement
how do capillaries solve diffusion problems
- diffusion works fine when cells are close to capillaries, but cells further back struggle with nutrition and waste (flux of materials)
- more capillaries = shorter diffusion distances, increasing plumbing is a solution
mouse capillary experiment
- mice put in low oxygen and grew more capillaries in thin ear tissue
- increasing amount of blood vessels allowed greater oxygen delivery to cells
***another possible solution to low O2 environment: increase amount of hemoglobin (protein that carries it)
connectivity of systems for metabolism
- multicellular organisms have a gas exchange surface (respiratory system) and a mechanism for delivering gas in/out of the system (cardiovascular system)
Highly connected!
diversity of respiratory surfaces
- we can use words like “more derived” or “less derived”, no system is better
examples
- transdermal: diffusion through skin
- spiracles on grasshoppers squeeze air in and out
- gills highly efficient at extracting oxygen from water (very little oxygen in water)
respiratory anatomy of mammals
large conducting airways
-cartilage (strong, prevents collapse), cilia (moves detritus up and cleans), smooth muscle
small airways (alveoli) - some smooth muscle (can cause asthma problems if too tight), no cartilage/cilia because gas exchange (needs to be thin)
how does airway diameter impact airflow?
- airway becomes narrower when smooth muscle contracts, asthma can cause this
- albuterol is smooth muscle relaxer
how does gas exchange work in the alveoli?
- capillary wall is one cell thick
- materials diffuse in and out at the same time, O2 going to blood and CO2 leaving blood move independently
CF complications with cilia
- cilia don’t function properly in people with CF, so the lungs can’t be cleaned out
what factors impact ability to oxygenate blood?
- amount of air moved in/out of lung
- size of conducting airways (asthma can shrink)
- number of alveoli (emphysema from smoking can decrease)
- number of functioning alveoli (pneumonia and illnesses cause non-functioning alveoli with fluid)
- alveoli blood flow (clots)
importance of lung surface area
- lung SA is huge which allows for fluctuations in our metabolic rate (more oxygen needed)
- tissue consumes 5L of oxygen per minute when exercising
- as SA increases moving down the lung (branching), velocity of oxygen decreases
what is partial pressure
- partial pressure = % gas in atmosphere x barometric pressure
- includes both a concentration component (oxygen is 21% of gas in atmosphere) and a pressure component (weight of atmosphere)
how does gas equilibration work?
- directional movement of gas based on partial pressure, not concentration!!
- takes 0.25 seconds to equilibrate in alveoli, so lungs are rarely limiting factor in ability to oxygenate
how does partial pressure change across locations?
% oxygen in atmosphere stays the same but barometric pressure changes, so partial pressure changes
oxygen cascade in the respiratory system
oxygen levels decrease as you approach the “end user” of the cell
ambient air - alveolar gas - arterial blood - capillaries - mitochondria
partial pressures of oxygen in air and within the body
- ambient air: 150-160 mmHg
- alveoli/arterial: 100 mmHg
- venous: 40 mmHg
partial pressures of carbon dioxide in atmosphere and in body
- ambient air: ~0.3 mmHg
- alveoli/arterial: 40 mmHg
- venous: 46 mmHg
why won’t alveolar gas levels match the ambient air?
- alveoli are mixing chambers; we never fully expel the air
- impossible to reach PO2 as high as in the atmosphere with this left over air