Gas Exchange Flashcards
Pulmonary ventilation equation (volume of air breathed in or out in one minute)
Tidal volume (volume of air breathed in per breathe at rest) x breathing rate (number of breaths per minute)
Ventilation mechanism of a fish and structure of gills for efficient gas exchange
Many lamellae, secondary lamallae
Counter current system of blood and water, equilibrium never reached, concentration gradient maintained across entire lamallae
Large number of capillaries, maintains gradient by removing oxygen
Thin epithelium of capillaries
Pressure changes (opening and closing mouth) to bring in more water/ maintain gradient
Insect gas exchange system
Spiracles, trachea, tracheoles
Spiracles allow diffusion of oxygen/ oxygen diffuses though trachea/ tracheoles
Tracheoles are highly branched so large surface area for exchange
Tracheole walls are thin so short diffusion pathway/ tracheoles enter cells so short diffusion pathway
Tracheole permeable to oxygen/air
Cuticle/chitin/exoskeleton impermeable so reduce water loss
Spiracles can close so no/less water loss/ spiracles have valves so reduced water loss
Hairs around spiracles reduce water loss
Rhythmic abdominal movements
Gas exchange in leaves of dicotyledonous plants (mesophyll and somata)
Mesophyll cells have large surface area
Stomata can open and close to balance between regulating water loss and gas exchange
Layers of leaf
Waxy cuticle
Upper epidermis
Palisade mesophyll tissue
Spongy mesophyll
Lower epidermis
Waxy cuticle
Adaptations of leaf
Broad
Palisade layer has lots of chloroplasts
Upper epidermis is transparent
Xylem and phloem form network of vascular bundles which provide less with water for photosynthesis and take away glucose produced and add support
Epidermal tissues covered with waxy cuticle to reduce water loss by evaporation
Lower epidermis has lots of stomata
Spongy mesophyll tissue contain air spaces which increase rate of diffusion of gases into and out of the leaf’s cells
Plant adaptations to extreme environments (heat)
Small leaves/ spines instead of leaves to reduce surface area for water loss by evaporation
Curled leaves/ hairs to reduce air flow
Thick waxy cuticles
Thick fleshy stem to store water
Fewer stomata/only open at night
Stomata sunken in pits
Insects controlling water loss
Close spiracles using muscles
Waterproof waxy cuticle
Tiny hairs around spiracles
Mechanism of breathing in
Diaphragm contracts and flattens
External intercostal muscles contract and rib cage moves up and out
Volume increase and pressure decrease in thoracic cavity (to below atmospheric pressure)
Active process
Mechanism of breathing out
Diaphragm relaxes and moves up/becomes curved again
External intercostal muscles relax and rib cage moves down and in
Volume decreases, pressure increases in thoracic cavity (to above atmospheric pressure)
Passive process
Forced expiration
External intercostal muscles relax and internal intercostal muscles contract, pulling the rib cage further down and in
Antagonistic muscles
Tidal volume
Volume of air in each breath
Ventilation rate
Number of breaths per minute
Forced expiratory volume
Maximum volume of air that can be breathed out in one second
Bronchioles
Forced vital capacity
Maximum volume of air it is possible to breathe out forcefully out of the lungs after a deep breath in
Lungs
The volume of water passing over the gills increases if the temperature of the water increases. Suggest why
Increased metabolism/ respiration/ enzyme activity
Or
Less oxygen dissolved in water
A rise in the temperature of water decreases the amount of oxygen dissolved in the water. As the water temperature rises, the rate of ventilation in a fish also rises. Explain the advantage of this
Metabolic rate/ respiration increases with an increase in temperature so more oxygen is required
To provide same amount of oxygen, need to have more water flowing over gills
Reduced elasticity of the lungs causes breathing difficulty. Explain how
Alveoli/ lungs won’t inflate/ deflate fully/ reduced lung capacity
Breathing out particularly affected, no longer passive
Reduces conc grad
Describe the difference in the composition of gases in inhaled and exhaled air and explain how these differences are caused
Inhaled air contains more oxygen than exhaled air
Exhaled contains more carbon dioxide than inhaled
When air is inhaled into the alveoli, oxygen diffuses down its concentration gradient into the capillaries while carbon dioxide in blood returning to lungs from body diffuses down its concentration gradient from the capillaries to alveoli
Inhaled air contains less water vapour
Relative amount/ percentage of nitrogen also changes
Water vapour diffuses from moist surface pf mouth and lungs
People who have been fire breathers for a longtime often find they cannot breath out properly, explain why
Inhaled mist causes scar tissue (fibrosis) to form
Scar tissue is thicker and less elastic
Elastic recoil reduced
In coeliac disease, the cilia are damaged. Although people with this disease can digest proteins, they have low concentrations of amino acid in their blood
Explain why
Reduced surface area so less absorption
Membrane bound enzymes less effective so proteins not digested
Cell membranes damaged so fewer/ less effective carrier/ channel proteins
Carrier/ channel proteins damaged so less absorption
Describe how humans breathe in and out
Diaphragm contracts and flattens
External intercostal muscles contract amd rib cage moves up and out
Volume increase in thoracic cavity to below atmospheric pressure
Diaphragm relaxes and moves up
External intercostal muscles relax and ribcage moves down and in
Volume decrease and pressure increase in thoracic cavity to above atmospheric pressure
Describe how the structure of the insect gas exchange system:
Provides cells with sufficient oxygen
Limits water loss
Spiracles, trachea, tracheoles
Spiracles allow diffusion of oxygen or diffusion of oxygen through trachea/ tracheoles
Tracheoles are highly branched so large surface area for exchange
Tracheole walls thin so short diffusion pathway to cells or highly branches so short diffusion pathway or tracheoles enter cells so short diffusion pathway
Tracheole permeable to oxygen/ air
Cuticle/ chitin/ exoskeleton impermeable so reduces water loss
Spiracles can close so no/ less water loss or spiracles have valves (same reasoning)
Hairs around spiracles reduce water loss
