Exchange and transport systems Flashcards
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
How are amino acids absorbed into the bloodstream?
They’re absorbed via co transport
Sodium ions are actively transported into the blood
Creates a gradient
Sodium ions carry the amino acids as they diffuse through sodium dependent transporter proteins
Talk about the structure of haemoglobin
Found in red blood cells Large protein with a quaternary structure Haem group containing iron ion High affinity for oxygen Hb + 4O2 = HbO8
What will a high partial pressure of oxygen do to affinity?
Oxygen loads onto haemoglobin in high partial pressure of oxygen, forming oxyhaemoglobin
Oxygen unloads from haemoglobin in low partial pressure of oxygen
What is the Bohr effect?
Cells respire producing co2
Raises partial pressure of oxygen
Increases the rate of unloading
The dissociation curve shifts to the right
How can organisms affinity differ sue to their environment?
Organisms living in areas of low oxygen have haemoglobin with a higher affinity, their curve shunts to the left
Organisms with a high demand for oxygen have haemoglobin with a low affinity for oxygen, their curve shunts to the right
What are the properties of an artery?
Carry blood from the heart
Thick muscular walls, allows for stretch and recoil maintaining high pressure
Folded inner lining, allows stretch to maintain high pressure
What are the properties of an arteriole?
Form a network around the body
Can vasoconstrict and vasodilate
What are the properties of a vein?
Take blood back to the heart
Wider lumen
Very little elasticity
Helped by contraction of body muscles
What do capillaries do?
Found near cells in exchange tissues
One cell thick
Large numbers, large surface area
How is tissue fluid formed?
Hydrostatic pressure is high at capillary bed, low in tissue fluid
The difference forces fluid into spaces around cells
This reduces hydrostatic pressure at venule end
Water potential in venule end is lower than tissue fluid
Some water re enters via osmosis
Discuss the structures found in the right side of the heart
Blood enters right artery via vena cava
Passes AV valve into right ventricle
Blood pumped up the pulmonary artery passes semi lunar valve
Discuss the structures found in the left side of the heart
Blood enters the left artery via the pulmonary vein
Passes AV valve into left ventricle
Blood is pumped up the aorta and passes the semi lunar valve
Talk about atria systole
Ventricles are relaxed
Atria contract, increases the pressure
AV valves open and blood is pushed into the ventricles
Talk about ventricular systole
Atria are relaxed
Ventricles contract, increases pressure to higher than in the atria
AV valves shut preventing backflow
Pressure in ventricles is higher than aorta
Semi lunar valves open and blood is forced out
Talk about diastole
Ventricles and atria relax Blood returns to the atria Increasing pressure in the atria Pressure drops in ventricles to below And AV valves open
How does an atheroma form?
Damage occurs to the endothelium
White blood cells and lipids clump under the lining
Over time this hardens forming an atheroma
This blocks the lumen and restricts blood flow
What is Coronary Heart Disease?
A type of cardiovascular disease where lots of atheroma’s cause blood flow to be restricted
Leading to myocardial infarction
What is an aneurysm?
Atheroma causes damage weakening the artery wall
Narrow causing high blood pressure
As blood travels through at a high pressure thin layers can be pushed out causing swelling
When an aneurysm bursts a haemorrhage occurs
What is thrombosis?
An atheroma plaque can rupture through the wall
Damages the artery wall
Platelets and fibrin accumulate and make a blood clot
This can cause a complete blockage or can become dislodged and block elsewhere
How does interrupted blood flow cause myocardial infarction?
If artery becomes completely blocked this area of the heart receives no oxygen
Causes a heart attack
This may result in the damage or death of heart muscle
How des high cholesterol increase the risk of coronary heart disease?
Cholesterol is a huge part o the fatty deposits causing an atheroma
Atheroma’s cause high blood pressure and blood clots
This could cause blockage to coronary arteries
(Diet high in salt and saturated fat is thought to higher the risk)
How does smoking increase the risk of coronary heart disease?
Nicotine causes high blood pressure
Carbon monoxide combines with haemoglobin reducing oxygen transported in blood
A decrease in antioxidants in the blood means less protection of cells to damage
How does high blood pressure increase the risk of coronary heart disease?
High blood pressure increases the risk of damage to the artery walls
This increases the risk of an atheroma forming
They cause a higher risk of blood clots and can block blood flow
(Being overweight, not exercising and excessive alcohol consumption)
What is the role of xylem tissue?
Transport water and minerals in solutions
Long tube like structures
No end walls
What is the role of phloem tissue?
Transport organic substances like sugars
How does water move up the plant against gravity?
Water evaporates out leaves
Creates tension pulling water into the leaf
Water is cohesive therefore more water molecules follow
What is transpiration?
Water evaporates from cell wall
Stomata open and it moves out the leaf down the concentration gradient
What four factors effecting transpiration rate?
Light, when it’s dark stomata close
Temperature, higher temp means faster evaporation
Humidity, low humidity means a concentration gradient causing faster movement
Wind, faster wind means water molecules are blown away faster
