Form and Function
Gas Exchange
Gas Exchange Surfaces
Permeable
Large
Moist
Thin
Concentration Gradient
Capillary System
Ventilation
Mammalian Lungs
Trachea
Bronchi
Bronchioles
Alveolar ducts
Alveoli
0.2 - 0.5 mm
Single Layer Wall
Collagen Fibers
300 mil in adult
40 x greater than outer surface
Pulmonary Surfactant
Reduces Surface Tension
Prevents Adhesion
Ventilation
Differential Air Pressure
Muscles
Inspiration
Diaphragm
External Intercostal Muscles
Volume Increases, Pressure Decreases
Expiration
Abdomen Wall
Internal Intercostal Muscles
Volume Decreases, Pressure Increases
Lung Volume
Tidal Volume
Vital Capacity
Inspiratory Reserve
Gas Exchange in Leaves
Chloroplasts
Carbon Dioxide Demand
Oxygen Waste
Adaptations
Avoiding Water Loss
Waxy Cuticle
Low permeability
Allowing Gas Exchange
Stomata
Guard Cells
Close at Night
Close During Water Stress
Spongy Mesophyll
Air Spaces Inside Leaf
Large Surface Area
Moist Surface
Transpiration
Evaporation in Leaves and Stems
Environmental Factors
Temperature
Positive Correlation
Humidity
Negative Correlation
Potometer
Stomal Density
Number of Stomata Per Unit Area of Leaf
Methods
Peeling Sample
Nail Varnish
Transport
Capillaries
Structure
10 micrometers diameter
Endothelium cells
Extracellular fibrous proteins (gel) called basement membrane
Filters out macromolecules
Pores between endothelium cells
Blood plasma, but not RBC
Fenestrated Capillaries
Large Pores
Large Volume of Tissue Fluid
Glomerus of Kidney
Distribution in Body
All active cells close to a capillary
Density in tissues depends on needs of cells
Arteries
Carry Blood Away from Heart
High Pressure Blood
Adaptations
Layered Wall
Tunica Externa
Tough Outer Layer with Collagen
Tunica Media
Thick Smooth Muscle with Elastin
Vasoconstriction
Reduces Flood Flow
Vasodilation
Increases Blood Flow
Tunica Intima
Smooth Endothelium Lining
Narrow Lumens
High BP
High Velocity of Blood Flow
Elastic Fibers
Store and release potential energy of Heartbeat
Reduce energy expenditure for blood transport
Semilunar Valves
Close during recoil, preventing backflow of blood to heart
Veins
Carry Blood Towards the Heart
Low Pressure Blood
Adaptations
Continuous flow, no pulse
Low pressure, risk of backflow
Pocket Valves
Gravity
Adjacent Muscles
Thin walls
Squeezing
Measuring Pulse
Pulse
Wave of high pressure blood passing along arteries
One pulse per beat
Pulse allows us to deduce heart rate
Wrist
Oxygen Saturation
Red Light Absorption