ORGANISMS AND ENVIRONMENT Flashcards
TOPIC 3
SURFACE AREA: VOLUME RATIO
surface area of an organism divided by its volume
larger organism, smaller ratio
FACTORS AFFECTING GAS EXCHANGE
surface area: volume ratio
diffusion pathway
concentration gradient
INSECTS USE TRACHEA TO EXCHANGE GASES
.Insects need to exchange gasses, but also need to need to limit water loss. These are opposing needs
.Branched, chitin-lined system of tracheae w/openings called spiracles
.Fast exchange of gasses as diffusion distance small at tracheoles
.No transport system as exchange is directly w/respiring tissues
.Body can be moved by muscles to move air so maintains concentration gradient for O2 and CO2
.Fluid in end of tracheoles that moves into tissues during exercise so faster diffusion through air to gas exchange surface-water potential lowered by osmosis
INSECTS REDUCE WATER LOSS
.have spiracles
.contain waterproof waxy cuticle + hairs around spiracles reduce evaporation
EXPLAIN MOVEMENT OF OXYGEN TO GAS EXCHANGE SYSTEM OF INSECT AT REST
oxygen used in respiration
oxygen gradient
oxygen diffuses in
HOW FISH PROVIDE LARGE SA:V RATIO
fish gills stacked gill filaments covered in many gill lamellae are positioned at right angles creates large SA for efficient diffusion
gills have lots of blood capillaries and are thin for short diffusion pathway
COUNTERCURRENT SYSTEM
When water flows over gills in opposite direction to flow of blood in capillaries equilibrium not reached diffusion gradient maintained across entire length of gill lamellae-this maintains concentration gradient of oxygen
GAS EXCHANGE IN PLANTS
Palisade mesophyll is site of photosynthesis
O2 produced and CO2 used creates concentration gradient
oxygen diffuses through air space in spongy mesophyll and diffuse out stomata
PLANT REDUCE WATER LOSS
.Stomata are usually open during day to allow gas exchange
.Water enters guard cells and they become turgid, so open
.plant becomes dehydrated guard cells lose water and become flaccid
.Xerophytes are plants adapted for hot and dry conditions- lowers water potential as less water lost by osmosis as it traps moisture eg. Marram grass
.Rolled leaf shape as upper epidermis is facing inwards to trap humid air
.Reduced leaf surface area for transpiration
.Sunken stomata, humid air is trapped reducing water potential gradient between inside leaf and humid trapped air
.No stomata on exposed lower surface
.Hairs, trap moist air
.Thick cuticle, waxy covering reduced evaporation
GAS EXCHANGE IN PLANTS (DICOTYLEDONOUS PLANTS)
.occurs through stomata on lower epidermis
.Stoma are openings which allow for exchange of carbon dioxide and oxygen-opened by ions which move in by active transport- allows water loss
.Stomata open to guard cells bending due to becoming turgid -Water moves by osmosis + water potential being decreased
ADAPTION OF ALVEOLI
.many alveoli= large surface area
.Alveolar epithelium and capillary endothelium are just one cell thick
.Short diffusion distance for O2 and CO2 between air and blood
.Many capillaries close to alveoli to maintain good blood supply and maintain steep concentration gradient
.Well ventilated to bring O2 to the surface and take CO2 away and maintain steep concentration gradient for O2 and CO2
STRUCTURE OF MAMMALIAN BREATHING SYSTEM PROVIDES EFFICIENT UPTAKE OF O2 TO BLOOD
- alveoli provide a large surface area
- walls of alveoli thin to provide a short diffusion pathway
- walls of capillary thin provides short diffusion pathway
- walls have flattened cells
- cell membrane permeable to gases
- many blood capillaries provide large surface area
- intercostal muscles maintain concentration gradient;
- wide trachea flow of air
- cartilage rings keep airways open
PASSAGE OF GAS EXCHANGE IN HUMANS
Mouth / nose -> trachea -> bronchi -> bronchioles -> alveoli -> alveolar epithelium -> capillary endothelium
INSPIRATION
External intercostal muscles contract and internal relax pushing ribs up and out diaphragm contracts and flattens
air pressure in lungs drops below atmospheric pressure as lung volume increases
air moves in down pressure gradient
EXPIRATION
External intercostal muscles relax and internal contract pulling ribs down and in diaphragm relaxes and domes air pressure in lungs increases above atmospheric pressure as lung volume decreases
air forced out down pressure gradient
VENTILATION RATE EQUATION
VR= TV x BR (breathing rate)
TIDAL VOLUME
volume of air in each breath
VENTILATION RATE
breaths per minute
FORCED EXPIRATORY VOLUME
maximum volume of air that can be breathed out in I second
FORCED VITAL CAPACITY
maximum volume of air breathed out forcefully after a deep breath
CARBOHYRATE DIGESTION
Starch is hydrolysed to maltose catalysed by amylase
Amylase is produced by salivary glands which release it into the mouth
Amylase is also produced by pancreas and released into small intestine
Membrane-bound disaccaridases are attached to membranes of epithelial cells in ileum
break down disaccharides eg. Maltose, into monosaccharides
using glycosidic bonds
LIPID DIGESTION
Lipids are hydrolysed to monoglycerides, and fatty acids catalysed by lipase
Lipase are made in pancreas and work in small intestine
Bile salts produced by liver emulsify large droplets of lipids into small droplets w/ larger surface area for lipase to work on monoglycerides and fatty acids form micelles w/bile salts using ester bonds
PROTEIN DIGESTION- HOW THE REACTION IS SPED UP
Endopeptidases hydrolyse bonds in protein + hydrolyse long polypeptides into shorter polypeptides- increases surface area for exopeptidase + speeds up full hydrolysis of proteins
Exopeptidase produced by pancreas and secreted into small intestine, hydrolyse bonds at end of proteins to remove single amino acids
Dipeptidases are located on cell surface membrane of epithelial cells in small intestine and separate dipeptides into two amino acids
PROTEIN DIGESTION-USING TRANSPORT METHODS
fallicitated diffusion of amino acid
co-tansport w/Na+ ion using carrier proteins
creates Na+ ion concentration gradient
Na+ is actively transported using ATP from cell to blood
fallicitated diffusion of amino acid out of blood