Mass Transport Flashcards
Why is there a small increase in pressure and in rate of blood flow in the aorta and whys it important
Elastic recoil of the aorta walls
Smooths blood flow/maintains blood pressure
What is the relationship between surface area and volume
The larger the organism the smaller the surface area to volume ratio
As volume increases, surface area to volume ratio decreases
What is Fick’s law
Diffusion rate= Surface area x Concentration gradient / Diffusion distance
What makes a good gas exchange system
Large surface area
Large concentration gradient
Thin exchange surface
How do larger organisms combat having a small SA:VOL
Developed specialised gas exchange systems and surfaces which have adaptations to ensure the rapid diffusion of gases
Why are cells usually limited in size
As cell size increases (volume) its surface area to volume ratio decreases
Meaning it can’t exchange substances efficiently or get materials fast enough to carry out its function
Smaller cells are more effective at transferring materials
What are the ways insects balance gas exchange and water loss
Waterproof covering: Over their bodies surface (usually rigid outer skeleton (an exoskeleton) covered with a waterproof cuticle
Small SA:VOL: Minimise the area over which water is lost
Specialised gas exchange system (trachea): Specialised internal gas exchange surfaces to minimise water and heat loss wh
What are the parts if an insects gas exchange
Tracheal system:
Spiracle
Trachea
Tracheoles
What is the name of an insects gas exchange system
Tracheal system
What is the purpose of spiracles
Tiny pores which gas enters and leaves the insect through
They open and close to control water loss by evapouration
They open when carbon dioxide levels increase
What is the purpose of the trachea
Network of tubes supported by strengthened rings
Lined with chitin
Which stops the tubes collapsing under low pressure
Providing tubes full of air so that diffusion can occur fast
What is the purpose of tracheoles
Small tubes with thin walls so the diffusion distance is reduced
They extend throughout the body tissue
Highly branched so there is a large surface area
Gas exchange occurs at the end of the tracheoles
How does the movement of oxygen occur in insects
Oxygen enters the insect through spiracles and into the trachea
Oxygen diffuses through the trachea into the tracheoles
Oxygen is delivered directly to the respiring tissue where it is used in the mitochondria of aerobically respiring cells
Keeping the oxygen concentration lower and maintaining a concentration gradient
How does the movement of carbon dioxide occur in insects
Waste carbon dioxide from aerobic respiration delivered to tracheoles
Diffuses from tracheoles into trachea then moves to spiracles
Carbon dioxide leaves insects through spiracles
Explain ventilation
Movement of insects muscles in their abdomen creates a mass movement of air in and out of the trachea
This speeds up the rate of gaseous exchange
Also have small air sacs in their trachea
Muscles around the trachea contract and pump air into the sacs deeper into the trachea
How is an insects tracheal system adapted for efficient gas exchange
Tracheoles have thin walls so short diffusion distance to cells
Tracheoles highly branches/large number of tracheoles so a short diffusion distance to cells AND a large surface area or gas exchange
Trachea provides full tubes of air so fast diffusion into insect tissues
Fluid in the end of tracheoles that move out into tissue during exercise so faster diffusion through air to gas exchange surface
Body can be moved by muscles to move air so maintains a diffusion/concentration gradient for oxygen and carbon dioxide
How do insects get additional oxygen during flight
At rest water can build up in the tracheoles
During flight the insect may partly respire anaerobically and produce some lactate (lactic acid)
This lowers the water potential of muscle cells
As lactate builds up water passes via osmosis from the tracheoles into the muscle cells
This adaptation draws air into the tracheoles closer to muscle cells and therefore reduces the diffusion distance for oxygen when it is needed
Improve the quality of a scientific drawing
Don't use shading Only use single, continuous lines Add lables/annotation Don't cross label lines Add a scale bar/magnification
Explain abdominal pumping in insects
Causes an increased pressure in abdomen (trachea)
More oxygen enters muscles more quickly
So maintains greater diffusion gradient
Compare and contrast bony and cartilagenous fish
Cartiligenous fish have a skeleton made of only cartilage whereas bony fish have an internal skeleton made from bone
Cartilagenous fish do not have an opperculum whereas bony fish do have an opperculum
Cartilagenous fish have 5-7 gills whereas bony fish have 4 pairs of girls
Cartilagenous fish use concurrent flow to exchange gases whereas bony fish use counter-current flow
Explain inspiration in fish
The mouth opens
The opercula on both sides close
The floor of the mouth (buccal) cavity is lowered
The volume inside the buccal cavity increases
The pressure inside the buccal cavity decreases
Water flows into the buccal cavity down as the external pressure is higher than inside the mouth (some water moves over gills) down a pressure gradient
How are fish gills adapted for efficient gas exchange
Many gill lamellae provide a large surface area for faster diffusion of gas
Thin epithelium of lamellae so a short diffusion pathway between water and blood
Counter current flow means water flows over the gills in the opposite direction to the blood flow in capillaries which maintains the concentration gradient along entire length of gill
Oxygen diffuses from water into blood as always next to blood with a lower concentration of oxygen
Blood circulation replaces the blood saturated with oxygen
Ventilation mechanism replaces the water over the gill surface
Explain how a counter current ensures maximum oxygen passes into the blood
Water and blood flow in opposite directions
Blood always passing water with a higher concentration of oxygen
Diffusion/concentration gradient maintained throughout the length of the gill lamellae/filaments
(Equilibrium not reached)
Gill lamellae vs filaments
Lamellae are smaller than filaments
Lamellae are in the filaments
Counter current vs con current
Counter current: no equilibrium is reached because concentration gradient is maintained all along the whole length of the gill lamellae
Con current: only maintained along part of it
Counter current: almost all of the oxygen in the water diffuses into the blood
Con current: only 50%
Briefly outline how oxygen and carbon dioxide enters and leaves a fish
Water containing oxygen enters through the fish mouth
Passes through the gill lamellae on the gill filaments
Where most of the oxygen removed
Water containing little oxygen and lots of carbon dioxide leaves through the gill opening
Dicotyledonous plant definition
Flowering plant
Xerophytic plant definition
Live in dry/arid environments
List the structures of a leaf
Waxy cuticle Upper epidermis cells Palisade mesophyll cells Spongy mesophyll cells Sub stomatal air spaces Lower epidermis cells Guard cells Stomata
Waxy cuticle
Water proof coat to reduce water loss through evaporation
Upper epidermis cells
Usually a single layer of lightly packed cells on the top and bottom of leaves
Palisade mesophyll cells
Where most photosynthesis occurs
Contain many chloroplast
Found towards the upper surface of leaf
Column shaped and packed closely together
Spongy mesophyll cells
Loosely packed for efficient gas exchange
Covered in a thing layer of water for gases to dissolve in as they move in an out of the cell
Lower epidermis
Usually a single layer of cells
Contain stomata and guard cells in between some cells
Guard cells
Control opening and closing of stomata
To allow for gas exchange and control water loss
If plants start to get dehydrated guard cells become flaccid and stomata close
Stomata
Open to allow gas exchange and close if too much water is being lost
How are leaves adapted for gas exchange
Flat so have a large surface area for faster diffusion
Many stomata allow movement of air in and out of leaf cells
Air spaces in the leaves make a short diffusion distance between the mesophyll and air
FINISH?
Explain the diffusion of carbon dioxide for photosynthesis
Mesophyll cells photosynthesise which reduces carbon dioxide concentration in the cells
Carbon dioxide diffuses from air spaces and into the cells
Reducing the concentration in the air spaces so carbon dioxide moves into the air spaces from the air outside the leaf through the stomata
Explain oxygen diffusion for photosynthesis
Mesophyll cells produce oxygen as a result of photosynthesis
Oxygen diffuses into the air spaces from the cells down a concentration gradient
Increased oxygen concentration in the air spaces
Causing oxygen to move from the air spaces to outside of the leaf via the stomata
How are plants adapted to reduce water loss
Air spaces are saturated with water vapour from the xylem and diffuses out of the stomata as it evaporates
Guard cells close at night to prevent water loss because less carbon dioxide required due to less sunlight for photosynthesis
Upper and lower surfaces have a waxy cuticle
Most stomata are found on the lower surface because its shaded and cooler so less evaporation
How are xerophytic plants adapted
Reduced number of stomata: less surface area for water loss
Stomata in pits: reduces water potential gradient
Hairs to trap water vapour: reduces water potential gradient
Rolled leaves: reduces water potential gradient
Leaes reduced spines: less surface area for water loss
Thick waxy cuticle: increased diffusion distance
How can SA:VOL be explained in terms of heat
As volume/size increases the surface area to volume ratio decreases
So a larger organism loses heat more slowly across its surface than a smaller one
Explain gas exchange in insects
Oxygen is used in respiring tissue which reduces the oxygen concentration in the tissue
Oxygen moves from an area of higher concentration in the trachea to an area of lower concentration in the tissue
This reduces the oxygen concentration in the trachea
So oxygen diffuses in from the air through the spiracles
Respiration produces carbon dioxide in the tissue of respiring cells
Increasing the concentration in the respiring tissue
Carbon dioxide moves from a higher concentration in the tissues to a lower concentration in the trachea
Then from the trachea to outside via spiracles down a concentration gradient
What is the operculum
A flap of tissue covering the gills of bony fish
What is a double circulatory system
Blood passes through the heart twice in one cycle
Pulmonary circulation
Blood passes through the heart and pumped to the lungs and returns back to the heart
Systemic circulation
Blood passing through the heart for a second time is repressurised and pumped to organs around body before returning to the heart
What is mass transport
Bulk transport of liquids and gases due to a pressure difference
E.g. blood moves around the body due to a high pressure in the heart and a low pressure in the blood vessels
Advantage of a closes system
Liquid within tubes
Are more efficient because its easier to generate and maintain a pressure gradient
Right atrium
Chamber on top right of the heart
That recieved deoxygenated blood from the vena cava
Right ventricle
Chamber on bottom right of heart That receives deoxygenated blood from right atrium
Left atrium
Chamber on top left of the heart
That recieves oxygenated blood from the pulmonary vein/lungs
Left ventricle
Chamber on the bottom left of the heart
That receives oxygenated blood from the left atrium
Aorta
Takes oxygenated blood from the left ventricle to the body
Vena cava
Superior: takes deoxygenated blood from the body above the heart to the right atrium
Inferior: takes deoxygenated blood from the body below the heart to the right atrium
Pulmonary vein
Brings oxygenated blood from the Lungs to the left atrium
Pulmonary artery
Takes deoxygenated blood from the right ventricle to the lungs
Coronary arteries
Branch off the aorta
Supply the heart with blood
Atrioventricular vavles
Between atrium and aorta
Open when pressure in atrium > pressure in ventricles
Close when pressure in atrium < pressure in ventricles
Semilunar valve
Between ventricle and aorta/pulmonary artery
Open when pressure in ventricles > aorta/pulmonary artery
Close when pressure in ventricles < aorta/pulmonary artery
Tendons/heart strings
Only let valves open one way
By anchoring the valve
How is blood returned to the heart
Deoxygenated blood from veins Muscles surrounding vein contract and press on walls to squeeze blood along Passes from the vena cava Into the right atrium Into the right ventricle Via the atrioventricular valve Due to a pressure gradient Through the semilunar valve Into the pulmonary artery Then to the lungs Valves prevent backflow Recoil of heart during diastole draws blood from veins into the atria
Path blood takes from heart to organs
Oxygenated blood from the lungs reaches the heart through the pulmonary vein
Volume of blood increases in left atrium so pressure increases
Causing atrioventricular valve to open
Blood enters the left ventricle
Down a pressure gradient because the pressure is lower in the ventricle
Volume of blood in ventricle increases so pressure increases until greater than in the atrium
So atrioventricular valve closes
Pressure in ventricle greater than in the aorta
So semilunar valve opens
Blood moves into the aorta down a pressure gradient
Blood goes into the coronary arteries and back to the heart and into arteries around the body to organs
Via arterioles
Systole
Contraction of heart muscle
Diastole
Heart muscle relaxed
What causes the pressure in the chambers
Change in pressure due to volume of blood within chambers and the contraction of the heart muscle
What happens in the cardiac cycle
Atrial systole
Ventricular systole (atrial diastole)
Diastole (atrial and ventricular)
Explain the cardiac cycle
1: Blood enters atrium, blood volume increases in atrium, so pressure increases to be greater than in ventricle, causes AV valve to open. Atrial systole further increases pressure so remaining blood forced into ventricle
2: Blood enters ventricle, blood volume increases so pressure increases to be greater than in atria, causing AV valve to close
3: Ventricle muscle contracts to further increase pressure in ventricle until greater than in the aorta/pulmonary artery, causing the semilunar valves to open. Blood enters aorta/pulmonary artery and pumped to body organs (left) or lungs (right)
4: Ventricle muscles relax so pressure in ventricle is less than aorta/pulmonary artery, causing semilunar valve to close
5: Blood enters the heart by pulmonary vein (left, oxygenated) and vena cava (right, deoxygenated) and the process repeats
How is the highest pressure produced in the left ventricle
Thicker walls/more muscle
So contractions are stronger and harder
Explain the opening and closing of the two valves in the heart
Atrioventricular: Open when pressure in atrium greater than in ventricle
Close when pressure in ventricle greater than in atrium
Semi-Lunar: Open when pressure in the aorta/pulmonary artery is greater than in the ventricles
Close when the pressure in the ventricle is less than in the pulmonary artery/aorta
How do the heart muscles and valves maintain a one way flow from the left atrium to the aorta
X
Formula for heart rate
CO=SC×HR
Cardiac output = Stroke volume × Heart rate
What is cardiac output
The volume of blood expelled from (pumped out of) the left ventricle pee minute (dm³min-1)
What is stroke volume
The volume of blood expelled from the left ventricle in one cardiac cycle
Adult at rest ≈ 75cm³
What is heart rate
The number of cardiac cycles per minute
Adult at rest ≈ 70bpm
CHD
Coronary Heart Disease
Refers to any interference with the coronary arteries which suppl the heart muscle with blood
What is atherosclerosis
The process of atheroma formation
Atheroma: A fatty deposit and cholesterol underneath the endothelium of the artery
What is thrombosis
The formation of a blood clot
What is an aneurysm
Swelling of an artery due to a blockage of blood flow
Describe the pathway taken by an oxygen molecule from alveolus to blood
Across alveolar epithelium
Endothelium of capillary
What happens when you become acclimatised to high altotudes
Oxygen carrying capacity of blood increases
Explain 4 ways in which the structure of the aorta is related to its function
Elastic tissue allows for stretch and recoil which maintains high hydrostatic pressure Muscle layer for vasoconstriction Semi-lunar valve prevents backflow Thick wall withstands pressure Smooth endothelium reduces friction
Explain the role of the heart in the formation of tissue fluid
Contraction of ventricles
Forces water out of pores between capillary and endothelium
Produces high hydrostatic pressure
What affects validity of conclusions
Representative samples Random sampling Control groups Length of study Statistical analysis Controlled variables Number of repeats
What affects validity of conclusions
Representative samples Random sampling Control groups Length of study Statistical analysis Controlled variables Number of repeats
