organisms exchanging substances Flashcards
What is the relationship between size of an organism and sa : v ratio
the smaller the organism, the larger the sa : v ratio
Describe the process on inspiration
external intercostal muscles contract causing ribcage to move up and out
diaphragm contracts and flattens moving down
volume of thoracic cavity increases and pressure decreases below atmospheric pressure so air rushes in
Describe the process of expiration
external intercostal muscles relax causing ribcage to move down and in
diaphragm relaxes and curevs moving up
volume of thoracic cavity decreases and pressure increases above atmospheric pressure so air rushes out
What is the spirometer?
a machine the doctor uses to measure lung volume
its consists of a chamber filled with oxygen
the lid moves up and down as person breathes
soda lime absorbs CO2 exhaled
What is forced expiration and what does it involve?
External intercostal muscles relax and internal contract moving ribcage further down and in
Explain gas exchange in insects
air-filled pipes called trachea have small pores called spiracles
each trachea branches off into trachioles which have thin permeable walls
CO2 moves in opposite direction and goes into atmosphere
oxygen travels down conentration gradient
How do insects prevent water loss?
exchanging gases results in loss of water vapour
if too much water is lost insect uses muscle to close spiracles
also covered with waterproof waxy cuticle and tiny hairs
Insection dissection method
place locust on back and pin onto dissection tray
make 4 cuts in shape of rectangle
gently peel exoskeleton
observe where trachea is
remove exchange surface area with tweezers and put onto glass slide
observe under microscope
Explain gas exchange in fish
Gills - water containing O2 passes across gills
each gill is made up of thin plates called gill fillaments attached to a gill arch
gill filaments have tiny structures called lamellae
Counter-current mechanism
Explain the counter-current mechanism in fish
blood and water flow in opposite direction
water has higher concentration of O2 than blood
steep concentration gradient created
O2 moves to lower concentration from water to blood
Explain the fish dissection
place fish on dissection tray and locate gills
use scissors to remove gill arch
wash gill fillaments with distilled water
use scalpel to cut off gill filament and view under microscope
Explain gas exchange in plants
gases enter/exit through stomata
stomata can open/close to prevent water loss - controlled by guard cells
during light hours CO2 enters for photosynthesis
when water enters guard cells it makes it turgid opening stomata
if plant is dehydrated guard cells become flaccid and close
What are xerophytes?
plants adapted to live in really warm windy or dry habitats
What are xerophyte adaptations?
Sunken stomata - allow moist air to be trapped
waxy cuticle - reduces water loss
hairy epidermis - traps moist air
fewer stomata - fewer areas of water loss
curled leaves - stomata protected from wind and water loss
Explain the role of the pulmonary artery
carries deoxygenated blood from heart to lungs
Explain the role of the pulmonary vein
carries oxygenated blood from lungs to heart
Explain the role of the vena cava
carries deoxygenated blood from heart to lungs
Explain the role of the aorta
carries oxygenated blood from heart to body
Explain the role of the renal artery
carry oxygenated blood from body to kidneys
Explain the role of the renal vein
carry deoxygenated blood from kidneys to heart
What are coronary arteries?
The blood vessels that supply the heart muscles with their own blood
What are the features of arteries?
Carry blood away from heart
thick muscular walls
folded and elastic endothelium
smaller lumen
carry blood at high pressure