B3.2 (Transport systems in plants and animals) Flashcards
What does the circulatory system consist of and what are their functions?
The heart - Muscular pump that moves blood around the body Blood - Carries substances around the body Arteries - Carry blood AWAY from the heart Veins - Carry blood towards the heart Capillaries - Tiny blood vessels near surface of skin where exchanges happen
What are the two circuits in the circulatory system?
A smaller circuit to the lungs
A larger circuit to the rest of the body
Where must blood go first before it is pumped around the body?
To the lungs
What is blood called that has come straight from the lungs?
Oxygenated blood
How does the heart pump blood around the body?
The muscles in the heart CONTRACT forcing blood out
Why is the left hand side of the heart larger than the right side?
Blood in the right hand side of the heart is pumped only to the lungs wheras the left hand side is pumped to the whole body and so needs more force
Where are the left and right atriums?
The top left and right
Where are the left and right ventricles?
The bottom left and right
What happens to blood when the heart beats?
Blood is collected in the atrium
When the heart beats it contracts and forces this blood into the ventricle
The second beat causes the heart to contract again and push the blood out through an artery
What is the passage of deoxygenated blood through the circulatory system?
- Deoxygenated blood enters the left side of the heart through the VENA CARVA
- Blood flows into the RIGHT ATRIUM where it is pumped to the RIGHT VENTRICLE
- The blood is pumped through the pulponary artery to the lungs
What is the passage of oxygenated blood through the circulatory system?
- Blood enters from the lungs through the PULMONARY VEIN
- Blood enters the left atrium and is pumped into the left ventricle
- Blood is pumped through the AORTA to the rest of the body
Why do valves sometimes need to be replaced?
A valve can become stiff and leaky and not be as efficient at being a one way valve in the heart, causing backflow of blood.
What are the advantages and disadvantages of biological valves?
+ Does not damage red blood cells
- Can harden over time
- Further operations may need to happen to replace the valves if it is a long term solution
What are the advantages and disadvantages of mechanical valves?
+ Strong and durable so will last a lifetime
- Can damage red blood cells
- Requires patient to take anti blood clotting medication for rest of life
- Reports of being able to hear valves opening and closing
Why can artificial hearts be more useful than biological / human hearts?
A heart transplant with a compatible donor can take a long time so patients often die while waiting for it
Why are artificial hearts only used as short term alternatives to human heart transplants?
Current designs can cause blood clots to build up within them and so they are used as short term measures until a donor is available
What are the characteristic of arteries?
- Carry high pressure blood from heart
- Thick walls
- Thick elastic fibres to allow surges of blood
- Thick layer of muscle to allow blood to be diverted
Thick walls and a thinner blood pathway
What are the characteristics of veins?
- Lower pressure compared to artery
- One way valves to prevent backflow of blood
- Thin walls
What is the lumen of a blood vessel?
The central cavity where blood flows
What is the purpose of the coronary artery?
To supply the heart with oxygen and glucose
What dangers can heart disease cause the coronary artery?
Fatty deposits build up on the walls of the coronary artery making the lumen narrower and therefore reducing the amount of oxygen and glucose that gets to the heart
How can arteries be made wider to prevent build up of fatty deposits?
A stent can be inserted through a blood vessel in the leg with a catheter
Once it enters a thin area of the coronary artery, a balloon is used to inflate the metal stent and keep the artery open
Why are stents used and what is a disadvantage of them?
Stents are used for people with heart disease instead of risky by-pass surgery
However, fatty deposits can build up on the stent itself
How are capillaries able to absorb waste substances and give out useful substances to and from organs and tissues?
Capillaries have very thin walls meaning a short diffusion pathway
They maintain a steep concentration gradient, absorbing urea to be excreted and giving out glucose and oxygen
What four parts make up blood?
Red Blood cells
White blood cells
Platelets
Plasma
What are red blood cells and what are they used for?
- BIOCONCAVE DISKS
- transports oxygen in the blood around the body
- Huge numbers of tiny cells with large surface areas
- Contain haemoglobin to transport oxygen and carbon dioxide
How are haemoglobins useful?
In oxygen rich environments, the oxygen combines with the haemoglobin to form oxyhaemoglobin
In low oxygen areas, the oxygen from oxyhaemoglobin is released so the area can gain more oxygen
eg
In lungs -> Oxyhaemoglobin
In body tissues -> Haemoglobin + oxygen
What are white blood cells?
Phagocytes and lymphcytes that engulf, ingest, or destroy pathogens with antitoxins, antibodies and phagocytosis
What are platelets?
Small fragments of cell that are useful in clotting blood and forming scabs to heal a wound
What is blood plasma?
- Makes up 55% of blood
- Carries nutrients such as hormones, antibodies, glucose, amino acids, urea and co2
Where does blood plasma transport different substances?
- Nutrients (digestion) from small intestine to organs
- CO2 from organs to lungs
- Urea from Liver to kidneys
What are the continuous tubes of xylem and phloem called?
Vascular bundles
What are xylem?
- Transport water from root to leaves
- Dead xylem cells with no cell wall make up the xylem tube
- The xylem itself has thick, reinforced cell wall to provide strength
What are phloem?
- Dissolved sugar and food from leaves to storage tissues and growing tissues
- Living cells with cell walls that form tiny holes called sieve plates
What is transpiration and the transpiration stream?
The evaporation and diffusion of water from a leaf
When this water evaporates, it pulls more water from the xylem into the leaf (as water cells are sticky) providing a constant stream of water into the leaf
What process sees water absorbed from the soil and passed though root cells?
Osmosis
Why does osmosis take place causing water to be transported throughout the plant?
When the water is absorbed into the root hair cell, it dilutes the concentration in that root hair cell forming a concentration gradient between that root hair cell and the root hair cells around it.
The water is osmosissed to these cells and the process is repeated again and again
How does light affect transpiration rate?
In bright ligth transpiration increases as the stomata open wider allowing more carbon dioxide into the leaf causing more photosynthesis causing more transpiration
How does Temperature affect transpiration rate?
In hotter temperatures transpiration is higher as evaporation adn diffsion happen faster at higher temperatures
How does wind affect transpiration rate?
In windier climates, transpiration happens faster as water vapour is removed quikly due to air movement
How does humidity affect transpiration rate?
In humid climates, tranpiration happens at a slower rate as the air around the leaf is already moist and SATURATED with water
How do guard cells regulate the amount of water loss in a plant?
If the guard cells are turgid and so have plenty of water, they expand forming a larger stomata to maximise the amount of carbon dioxide absorbed
If the guard cells are flaccid and so dont have enough water, they grow closer together, making the stomata smaller and so reducing the amount of water loss in photsynthesis
How does the rate of transpiration affect the rate of osmosis in the roots?
If more water is lost, more water will need to be gained by the roots to balance it out
