Exchange and transport systems Flashcards
(52 cards)
Which would have a bigger surface area: volume ratio, a mouse or a hippo?
The mouse
Why do multicellular organisms need exchange organs?
Because diffusion across the outer membrane would be too slow
Explain why a mouse would have a high metabolic rate
Because they have a large surface area to volume ratio
This means that heat is lost more easily
As a result they need to generate more heat to stay warm
Describe how fish use a counter current system for gas exchange
Water containing oxygen enters the mouth
Each gill made up of gill filaments coated with lamellae give a large surface area
Blood flows into lamellae in one direction
Water flows in the opposite direction
Maintains a concentration gradient
Oxygen diffuses from the water into the capillaries to oxygenate the blood
Describe how insects use tracheae for gas exchange
Air moves into pores on surface, spiracles
Oxygen moves down the concentration gradient to cells
Tracheae branch into tracheoles with thin permeable walls
Carbon dioxide moves the opposite direction down its gradient
How do plants use mesophyll cells for exchange?
The surface of mesophyll cells is the site of gas exchange
Gases move in and out of the stomata
Open to allow exchange of gases
Close when plant loses too much water
Guard cells control the opening and closing
How can insects and plants control water loss?
Insects close spiracles using muscles, waterproof waxy cuticle
Plants stomata open during day, water enters guard cells and make them turgid this opens the pore, when dehydrated the water moves out and the pore closes
How can plants be adapted to dry environments?
Sunk stomata trapping moist air Layer of hairs on the epidermis Curled leaves protecting from wind Reduced number of stomata Waxy waterproof cuticles
Describe inspiration
Air enters the trachea, trachea splits into bronchi, splits into bronchioles, ends with the alveoli
External intercostals and diaphragm contract
Ribcage moves up and out, thoracic cavity increases
The pressure inside the lugs decrease to less than outside the lungs
Air passively moves in
Describe expiration
External intercostals and diaphragm relax
Ribcage moves in and down
The pressure inside the lungs increases to more than outside of the lungs
Air moves out of the lungs
How are alveoli adapted for efficient gas exchange?
Huge amounts of alveoli allow for large surface area
Network of capillaries surrounding allow for a short concentration gradient
One cell thick alveoli epithelium and alveolar endothelium allow for short distance
What is tidal volume?
The volume of air in each breath
What is ventilation rate?
The number of breaths a minute
What is forced expiratory volume?
The maximum amount of air breathed out in one second
What is forced vital capacity?
The maximum amount of air possible to forcefully breathe out of the lungs
How does tuberculosis affect the lungs?
When infected the immune system builds a wall around bacteria in lungs
Infected tissue dies and gas exchange surface is damaged, tidal volume decreased
How does fibrosis affect the lungs?
Formation of scar tissue in lungs
Thicker and less elastic
Lungs can’t hold as much air
Reduction in gaseous exchange
How does asthma affect the lungs?
Airways inflamed and irritated
During asthma attack the smooth muscle contracts and mucus is produced
Causes constriction of the airways and makes it difficult to breathe
How does emphysema affect the lungs?
Smoking or long term air pollution, foreign particles become trapped
Inflammation attracts phagocytes, break down the wall
Alveoli cannot recoil as effectively
Where are amylase and lipase made?
Amylase= salivary glands, pancreas Lipase= made in pancreas, work in the small intestine
What are endopeptidases and what do they do?
They hydrolyse peptide bonds within protein
eg, pepsin trypsin and chymotrypsin
What are exopeptidases and what do they do?
They hydrolyse peptide bonds on the end of protein, they remove single amino acids from the protein
How are glucose and fructose absorbed into the bloodstream?
Glucose is absorbed by active transport with sodium ions via a co transporter protein
Fructose is absorbed by facilitated diffusion through a transporter protein
How are monoglycerides absorbed into the bloodstream?
Micelles move monoglycerides towards the epithelium
Monoglycerides and fatty acids are lipid soluble and therefore diffuse directly across the membrane
