B4: Organising Animals and Plants Flashcards
What is a single circulatory system?
A system where the blood passes through the heart once in a single circuit
What is a double circulatory system?
A system where the blood passes through the heart twice in a single circuit
What are the cons of a single circulatory system?
The blood uses a lot of pressure as it travels around the body,
meaning that the blood travels to the heart slower,
it is thus inefficient as it does not deliver much oxygen
Deoxygenated and oxygenated blood is mixed
What are the benefits of a double circulatory system?
Because the blood passes through the heart twice, it can travel faster to body cells and delivering oxygen
more efficiently
Oxygenated and deoxygenated blood are separated, meaning the body always has a dedicated supply of oxygen and improves efficiency
What is the heart and what is its function?
An organ containing mainly muscle tissue
Pumps blood around the body
What are the 4 chambers of the heart and where are they located?
Top left - left atrium
Top right - right atrium
Bottom left - left ventricle
Bottom right - right ventricle
How are the atria separated from the ventricles?
By valves, to prevent the backflow of blood
What is the function of the vena cava and where is it located?
Bring deoxygenated blood into the heart
Comes to the very right of the right atrium
What is the function of the pulmonary artery and where is it located?
Bring deoxygenated blood into the lungs to become oxygenated again
Centre-ish of the heart, right atrium
What is the function of the pulmonary vein and where is it located?
Bring oxygenated blood back into the heart
Very left of the heart, in the left atrium
Describe the pattern of blood flow through the heart
The blood enters into the atria which contract and force the blood into the ventricles.
The ventricles now contract and force the blood out of the heart through either the aorta or the pulmonary artery
The valves of the heart stop the blood from flowing backwards into the atria when the ventricles contract
Why does the left side of the heart have a thicker muscle wall?
The left side needs to pump blood around the body (as opposed to the right which only needs to pump blood to the lungs), thus it needs to provide a greater force
What are the coronary arteries and what is their function?
Arteries which branch out of the aorta and spread to the heart muscle
They provide oxygen to muscle cells of the heart to provide energy for contraction
What controls the natural resting rate of the heart and where is it found?
A group of cells called the pace maker
Found in the right atrium
How can irregular heartbeat be treated?
Implant an artificial pacemaker (small electrical device which corrects heartbeat
What is an artery?
Pumps oxygenated blood from heart to the body cells at high pressures
How are the arteries adapted to their function?
Thick muscular walls - withstand the high pressure of the blood
Elastic fibres - blood travels through the body in surges, fibres stretch and recoil between surges to keep the blood moving
What are capillaries?
Allow the exchange of substances between the blood and cells e.g oxygen and glucose to cell, carbon dioxide to capillary
How are capillaries adapted to their function?
Thin walls - short diffusion path, therefore more efficient exchange
What are the veins?
Take deoxygenated blood back into the heart, slowly and at lower pressure
How are veins adapted to their function?
Thin wall - low pressure, thus no need to be thick
Valves - stop backflow of blood
What are the 4 main components of the blood?
Plasma
Red blood cells
White blood cells
Platelets
What is the plasma and what is its function?
The yellow liquid part of the blood
Transports dissolved substances around the body e.g. soluble digestion products (like glucose), carbon dioxide (to be breathed out) and urea (waste to be excreted)
What are the red blood cells and what is their function?
Red biconcave disks
Transport oxygen from the lungs to the body cells
What is the structure of a red blood cell?
Contain haemoglobin (which carries oxygen as oxyhaemoglobin)
No nucleus, more space for haemoglobin
Biconcave disk, greater SA so oxygen diffuses more rapidly
What are the white blood cells and what is their function?
Part of the immune system, responsible for making antibodies
What is the structure of a white blood cell?
Have a nucleus
What are platelets and what is their function?
Tiny fragments of cells which help the blood to clot
What are the uses of donated blood in medicine?
To replace lost blood during injury
Some people are given platelets extracted from blood to help with clotting
Proteins extracted from blood can be useful to make antibodies
What are some problems with donated blood?
Blood must be the same type as the patient’s
Risk of disease transmitted via blood
Why must donated blood be the same blood type as the patient’s?
The body’s immune system will reject the blood and the patient will die
What are cardiovascular diseases?
Diseases of the heart and blood vessels
Non-communicable
What are some examples of cardiovascular diseases?
Coronary heart disease
Leaky/ faulty valves
What is coronary heart disease?
Layers of fatty material build up inside the coronary arteries, narrowing their lumen and reducing the flow of blood through the arteries
It can lead to a heart attack, where the heart is starved of oxygen
What are some treatments of coronary heart disease?
Statins - drugs which reduce the amount of cholesterol and slows the rate at which fatty material builds up in the arteries
Stent - used for total blockage, a tube inserted into the artery to keep it open
What are the advantages of statins?
Effective
What are the disadvantages of statins?
Liver problems
Must be taken regularly, patient might forget.
What are the advantages of stents?
Blood can flow normally
What are the disadvantages of stents?
Does not treat the cause of the disease
Does not prevent fat from building up elsewhere in the artery
What are possible problems regarding heart valves?
Valves don’t fully open, heart has to pump extra hard to get the blood through (heart enlarges)
Valves are leaky (don’t close properly), causing the patient to fee fatigued
How can faulty valves be fixed?
Replace with either a mechanical valve or a valve from a pig (animal)
What are the pros and cons of mechanical valves?
Adv - last a lifetime
Dis - increase the risk of blood clots, anticlotting drugs required
What are the pros and cons of using an animal valve?
Adv - no drugs needed
Dis - may need to be replaced
What is heart failure?
When the heart cannot pump enough blood around the body
How can heart failure be treated?
Donated heart/ lungs
What are the problems with treating heart failure?
Not enough donated hearts to treat every patient
Patient must take drugs to prevent rejection of the new heart by the immune system
What is the purpose of artificial hearts?
A temporary heart while the patient waits for a new transplant or
to allow their damaged heart to rest
What are the problems with artificial hearts?
Increased risk of blood clots
Not a long-term solution
What are the main components of the lungs and what are their functions?
Trachea - where air enters the lungs, splits into
Bronchi - smaller tubes passing into each lung, subdivide into
Bronchioles - smaller tubes
Alveoli - microscopic air sacs at the ends of the bronchioles
What is the structure of the trachea?
A long tube with rings of cartilage which prevent it from collapsing during inhalation
What is the purpose of alveoli?
Where gasses diffuse in and out of the bloodstream - they are the sites of gas exchange
How are alveoli adapted for gas exchange?
Millions of alveoli have a huge surface area
Thin walls - short diffusion path
Good blood supply, steep concentration gradient
What is the leaf?
The plant organ responsible for collecting light for photosynthesis
What is the purpose of the epidermal cells in the leaf?
Epidermal cells - coat the top and bottom of the leaf and they form epidermal tissue (lower and upper epidermis (transparent to let light reach chloroplasts)) which protects the surface of the leaf
What is the purpose of the waxy cuticle in the leaf?
Waxy cuticle - thin oily layer which coats the upper epidermis - prevents the leaf from drying out by reducing water loss through evaporation
What is the purpose of the stomata in the leaf?
Stomata - tiny pores on the lower epidermis, allow carbon dioxide to enter and oxygen to leave and control the amount of water vapour that can pass out of the leaf. They are controlled by guard cells
What is the function of the palisade mesophyll in the leaf?
Palisade mesophyll - directly under the upper epidermis, packed with chloroplasts containing chlorophyll
What is the function of the spongy mesophyll in the leaf?
Spongy mesophyll - directly under the palisade mesophyll, full of air spaces which allow carbon dioxide to diffuse from the stomata through the spongy mesophyll to the palisade cell and oxygen the other way round
What is the function of the xylem tissue in the leaf?
Xylem - transfers water and dissolved mineral ions (e.g. magnesium used to make chlorophyll) from the roots to the leaf, some water is used for photosynthesis
What is the function of phloem tissue in the leaf?
Phloem - transports dissolved sugars produced by photosynthesis from the leaves to the rest of the plant, which can be used immediately for respiration or stored as starch (translocation)
What is the function of meristem tissue in plants?
Meristem - found growing on the tips of shoots and roots, contains stem cells which can differentiate in to different types of plant tissue
What is transpiration?
The process of water leaving the leaf through evaporation
Describe the process of transpiration
Starts with the evaporation from cells inside the leaf, water vapour the diffuses through the spongy mesophyll and leafs through the stomata.
Water is drawn up from the root hair cells and then it passes into the xylem, then to the leaf to replace the water that has been lost
What is the importance of transpiration?
Evaporation from the water cools the leaf down
Water is required for photosynthesis
Mineral ions are brought by the transpiration stream
What factors affect the rate of transpiration?
Temperatures - high temp = higher transpiration rate, evaporation is faster at higher temperatures
Wind - more wind = higher transpiration rate, wind removes any water vapour
Light intensity - higher = higher transpiration rate, stomata now open to let more carbon dioxide for photosynthesis so more water vapour is lost too
