Gas Exchange in Organisms

Gas Exchange

• All organisms, irrespective of size, participate in gas exchange, absorbing some gases and releasing others.
• Gas exchange can occur across the organism surface provided there is a high surface area to volume ratio
• Larger organisms need a specialized surface for gas exchange because they have smaller surface area to volume ratio

Features of Gas Exchange Surfaces

• Cells of an organism must be exposed to an environment at a gas exchange surface.
• Gas exchange surfaces in terrestrial organisms are exposed to air, while aquatic organisms are exposed to water.
• Gases are exchanged by diffusion.
• Gas exchange surfaces should be permeable, large, moist, and thin

Importance of Concentration Gradients

• Diffusion follows concentration gradients
• Aerobically respiring cells maintains concentration gradients through cellular respiration.
• Pumping of blood is required to maintain concentration gradients in the lungs or gills
• Ventilation replaces air or water to maintain high and low enough concentration gradients of gases

Lung Structure and Ventilation

• Lungs reside in the thorax and air is intaken or let out by airways
• Ventilation entails muscle contractions that cause pressure changes inside the thorax which either draws air in or pushes it out
• Muscles that that cause this reaction are the diaphragm dividing the thorax and abdomen, the front wall of the abdomen and intercostal muscles between the ribs

Lung Adaptations

• Mammals use lungs for gas exchange with adaptations

Efficient Gas Exchange

• Branching bronchioles ventilates each lung, ending in alveolar ducts and then leading to five or six alveoli.
• Large surface area for gas exchange is ensured by the 300 million alveoli
• The surfaces of alveoli are covered by a netowrk of blood capillaries.
• Thin alveolus and capillary walls aid shortisng diffusion distances.
• Pulmonary surfactant moistens and prevents collapse of lung and is produced by cells in the alveolus walls.

Measuring Lung Volumes

• Lung volumes are measured as part of tests into general health to help diagnose breathing issues
• Ventilation rate is the number of breaths per minute
• Inhaled or exhaled air volume is called the tidal volume
• The maximum air exhaled after max inhalation is vital capacity
• A forceful volume is expiratory reserve volume
• A spirometer is used to measure the lung volumes

Leaves for Gas Exchange

• Chloroplasts need carbon dioxide and for photosynthesis and oxygen needs to be released
• The leaf uses a large moist surface area to absorb or excrete gases
• A waxy cuticle helps to reduce water loss from the epidermes cells
• Guard cells are pores which allow gases to pass through, they also close the stomata when photosynthesis isn't working
• The stomata are connected to a network of air spaces in the spongy mesophyll which is the inner leaf tissue and is extensive
• The veins replace water from the moist spongy mesophyll

Transpiration

• Evaporation of water occurs when hydrogen bonds break and the molecules separate, then become water vapour in the air
• Transpiration is affected by environmental factors that make gas exhange rates change

Transpiration environmental factors

• Higher temperatures raise evaporation rate
• Humidity is lower at a lower rate of diffusion
• Wind increases diffusion rates

Measuring Stomatal Density

• Stomatal density is the number of stomata per unit area
• You can measure it peel a leaves epidermis, or paint nail polish on it to peel off

Haemoglobin and Transport

• Fetuses produce feotal and adults produce haemoglobin
• Foetal haemoglovin has a stronger affinity to oxygen.

Bohr Shift

• Bohr shifts can raise carbon dioxide concentrations to reduce the affinity of haemoglobin with oxygen

Mechanisms of Bohr Shift

• The affinity of Haemoglobin for Oxygen correlates with ph
• CO₂ can bind to polypeptides in haemoglobin, producing lower affinity carbaminohaemoglobin.

Oxygen Dissociation Curves

• Each haemo subgroup carries 4 oxygens
• Binding is cooperative, since one creates affinity
• O2 amount is measured in kilopascals (kPa) 100% saturation occurs when it hits 10 kPa
• The lungs allow 100% blood oxygenation and it is carried to other body organs

Transport

• Capillaries are adapted for exchange
• Capillaries adapted for release and absorption processes
• Vessels are dense/tight network of capillaries and all body cells
• Capillarie are adapted to have large surface area, pores thinness of walls

Distinguishing Arteries and Veins

• Arteries pulsate, high pressure to organs
• Veins carry low pressure blood to heart
• 3 layers of arteries adapt it to pump blood away from heart

###Measuring Pulse Rates

• Pulse is felt in arteries, you can measure with your finger

Veins Help Return Blood

• Veins drain blood from capilaries
• Pressure in veins can drop, valves prevent collapse and ensure that blood in a certain direction

Epidemiological Data of Coronary Heart Disease

• Blood out of artery in the aorta and branches to body
• Lipids can deposits restrict flow and cause blocks
• Heart medical issues is called heart disease or coronary
• Risk factors are variables or traits which are associated with increase and include hight blood pressure etc

Water Transport Methods

• Plants transport water
• Xylem vessels transport most water and is low in various ions
• Water moves by cell adhesion

Adaptations for Pholem Tissue

• Helps with translocation of carbon

Xylem Vessels

• Help transport water Distribution of stem tissues.
• Stem has epidermis Dicot root tissue includes vascular bundle and phloem Measurement of lung volumes by simple machine and software

Tissue Fluid

• Oxygenated and nutrient blood inters the bodies
• Tissue fluid is pressure. Fluid passes through cells, allows absorbtion and excertion

Excess Tissue

• Excess drains to lymphatic system

Systems

Single Loop circulation vs Double Loop

• Fish heart has single pumping thing and its oxygen passes to body and gills
• As mammals it cycles to both sides

Adaptations of Heart

• Artia is collector
• Septum is wall.
• Cardiology helps

Heart Cycle

• 1 to 3 cycles

Muscle and Mobility

• For movements

Types of Muscles

• Relaxation is caused by potential energy from titin Skeletal muscles and contractions

Motor Units

Are muscles and neurons with a neuromuscular junction

Levers

• Bones act like levers Synovial helps joints Synovial joints

Joint Capsule

Made of collagen

Motion range

• Depends on elbow and other joints and is measured by the machines