Please enable JavaScript.
Coggle requires JavaScript to display documents.
Y2 Systems - Coggle Diagram
Y2 Systems
Electricity
Electric Current
Formed by moving charges
Measurement of the rate of flow of electric charges through a cross-section/point of a conductor
SI Unit
Ampere (A)
Measuring instrument
Ammeter
Connected in series to the circuit
Very low, negligible resistance
How does an ammeter work?
As the coil turns, the hair spring exerts a restoring force that is proportional to the angle that is turned through.
When these two forces balance, the coil stops.
The angular deflection of the coil is directly proportional to the current, so the meter can be calibrated to read current.
Ammeters have very low resistances, which is desirable as the impact of the ammeter on the circuit is then minimized.
Formula
I (electric current, amperes, A)
=
Q (electric charge, coulombs, C)
/
t (time, seconds, s)
For every 1 second, a certain amount of charges passes through a point in the circuit
The rate of flow of charges is no. of coulombs per second
1 A means for every 1 second, the amount of charge passing through a point in the circuit is 1C
SI Symbol
I
Types of Current
Conventional Current
Before the discovery of electrons, scientists believed that electric current was caused by the movement of positive charges.
Although this idea was later proven wrong, the idea remains.
This movement of positive charges is called conventional current.
Electron Flow
Electric current is caused by the flow of electrons from the negative to positive terminal
Electric Charge
Negatively charged electrons
SI Symbol
Q
SI Unit
Coulomb, C
Circuit Components
Switch
Method of opening or closing a circuit
Can be 1-way/2-way
Dry cell
Source of electromotive force to drive electric charges around the circuit
Battery
More than 1 dry cell
Direct Current Power Supply
Alternating Current Power Supply
Bulb
A load in which moving charges can do a useful job
Wires
Conductors connecting the components together
Fixed resistor
Variable resistor (Rheostat)
Fuse
Galvanometer
Earlier version of an ammeter
Ammeter
Measures electric current (rate of flow of charges through a point in the circuit)
Connected in series with the circuit
Very low, negligible resistance
Voltmeter
Measures voltage
Connected in parallel
Very high resistance
Earth connector
Learnt in practical circuitry
Capacitor
Device that stores electrical energy by accumulating electric charges on two closely spaced surfaces that are insulated from each other
OPEN CIRCUIT
A circuit in which current is unable to flow due to breaks in the circuit.
SHORT CIRCUIT
An alternative path of lower resistance is present and hence, current flows through another path (wire) instead of the desired (bulb).
Voltages
Electromotive Force (e.m.f) of a source of electrical energy
Work done by the source in driving a unit charge around a complete circuit
Voltage of the source/cell
Formula
E, electromotive force (e.m.f), volts, V
=
W, work done, amount of non-electrical energy converted into electrical energy, joules, J
//
Q, charge, coulombs, C
SI Symbol
E
SI Unit
Volt, V
Joule per coulomb (J C^-1)
Measuring instrument
Voltmeter
Positive and negative terminals should be connected to the respective terminals of the electrical source
Should be connected in parallel with the component
Very high resistance
Types
Direct voltage
Permanent Magnet Moving Coil Voltmeter.
Working Principle
3 more items...
Alternating voltage
Moving Iron Voltmeter.
Electro Dynamometer Type Voltmeter.
Rectifier Type Voltmeter
Electrostatic Type Voltmeter
Digital Voltmeter
Arrangement of Cells
When cells are arranged in series
Resultant e.m.f = sum of all the e.m.f in all cells
When cells are arranged in parallel
Resultant e.m.f = e.m.f of 1 cell in parallel
Potential Difference (p.d.) across a circuit component in an electric circuit
Work done to drive a unit charge through a circuit component
SI Symbol
V
SI Unit
Volt, V
Formula
V, potential difference (p.d.), volts, V = W, work done (amount of electrical energy converted to other forms), joules, J // Q, electric charge, coulombs, C
Measuring instrument
Batteries function like water pumps, which do work to drive water around the pipe, providing energy, and likewise, a battery does work to drive electrons around the circuit
Resistance
Measurement of how difficult it is for an electric current to pass through a material
The property of the material restricts the movement of free electrons in the material
Due to atomic/molecular/particle arrangement
Resistor/resistance added
Rate of flow of electric charges reduced
Current is reduced
Reading on ammeter will be reduced
Resistance of a component is the ratio of the potential difference (p.d.) across the component to the amount of current flowing through the component
SI Unit
Ohms, Ω
SI Symbol
R
Formula
R, resistance of a component, ohms, Ω = V, potential difference (p.d.) across a component, volts, V // I, current flowing through a component, amperes, A
Ohmic conductors have their
I, current, amperes, A directly proportional to the V, voltage, volts, V
I, current, amperes, A inversely proportional to the R, resistance, ohms, Ω
How to measure resistance
Circuit
Ammeter connected in series with the bulb
Voltmeter connected in parallel with the bulb
All circuit components have resistance
But for the ease of calculations
Dry cell
Assumed to have 0 resistance
Wires
Switches
Ammeter
Voltmeters
Considered to have ∞ infinite ∞ resistance
Resistance too high for any current to flow through
Resistors
Conductors in a circuit used to control the amount of current flowing through
2 types
Fixed
Variable Rheostat
Factors affecting Wire Resistance
Length
R ∝ L
Longer wire
Higher resistance
Shorter wire
Smaller resistance
Thickness
R ∝ 1/A
Thicker wires
Smaller resistance
Thinner wires
Higher resistance
SERIES VS PARALLEL
Series
Components connected one after another in a single loop
Only 1 path for electric current to flow through
CURRENT
All ammeters give the same readings
Same amount of current flows in and out of resistors or circuit components
I (total) = I1 = I2 = I3
Current at
every point is the SAME
POTENTIAL DIFFERENCE
Potential difference (p.d.) across the
whole circuit
is equal to the
sum
of potential difference (p.d.) across
each individual component
V (total) = V1 + V2 + V3
RESISTANCE
Total effective resistance is equal to the sum of all the resistances added up
Total effective resistance is always bigger than the highest individual resistance
R (total) = R1 + R2 + R3
POTENTIAL DIVIDER CONCEPT
The electromotive force of the cell is divided proportionally to the ratio of resistors in the circuit
V1 = R1/R1+R2 X V
V2 = R2/R1+R2 X V
V ∝ R
Voltage is directly proportional to resistance
V1 : V2 = R1 : R2
Parallel
Components connected to the cell providing electromotive force in 2 or more loops
Several paths through which electric current can flow
CURRENT
Current flowing from the cell splits at the junction of electrical pathways, and recombines at the other junction
Ammeter reading at combined junction equals to the sum of ammeter readings at individual pathways
I (total) = I1 + I2 + I3
POTENTIAL DIFFERENCE
Total potential difference across the whole circuit is equal to the potential difference across each resistor/circuit component
V (total) = V1 = V2 = V3
RESISTANCE
Reciprocal of effective resistance of resistors in parallel equals to the sum of all the reciprocals of all individual resistances
R (total) =
(
(1/R1) + (1/R2) + (1/R3)
)
^-1
Total effective resistance is always smaller than the smallest individual resistance
CURRENT DIVIDER CONCEPT
I ∝ R
Current is inversely proportional to the resistance of a branch
I1 = R2/R1+R2 X I
I2 = R1/R1+R2 X I
Practical Circuitry (Electrical Power/Consumption)
Electrical energy is converted into thermal energy via heating elements
Electric kettle
Electric iron
Electric radiator
Electric hotplate
Electrical Power
SI Symbol
P
SI Unit
W, Watt
1 W, watt = 1 J/s, joule per second
Formulas
P, power, watts, W = w.d., work done, joules, J // t, time, second, s
P, power, watts, W = V, voltage, volts, V X I, current, amperes, A
P, power, watts, W = (I, current, amperes, A) ^2 X R, resistance, ohms, Ω
P, power, watts, W = (V, voltage, volts, V) ^2 // R, resistance, ohms, Ω
Calculating Cost of Electricity
Energy consumed = P (power rating, watts, W) X t (time, seconds, s)
1 kWh = energy consumed by a 1 kW device in 1h
kWh x cost = total cost
Damaged Insulation
When the insulating material covering the conducting wires gets worn out or damaged, the wires conducting electricity may be exposed.
Exposed wires can cause electric shocks if touched
Overheating of Cables
Overheated cables can lead to fires
Causes
Overloaded power sockets
Unusually high current flows through the wires
Using inappropriate wires
Require higher power to function need thicker wires
Damp Environments
Water in contact with exposed electrical wires provides a conducting path for current
May lead to electric shocks
Electrical appliances should be kept in dry places and handled with dry hands
Fuse
Consists of a short, thin piece of wire
If the current flowing through it is too large, the wire heats up and melts
Causes circuit to be opened, no current can flow
Must be replaced after it blows
Fuses should have a current rating that is just slightly higher than the current used by the electrical appliance.
Types of Plugs
2 pin plug
Only live and neutral wires
Double insulation
Protects by preventing wires from touching outer surface and conducting electricity there
3 pin plug
Live wire
Brown in colour
Wire of high potential and voltage
Carries current to appliances
Contact results in electric shock due to potential difference
Current is same as neutral wire
Neutral wire
Blue in colour
Wire at 0V, no voltage,
Carries current from appliance back to main supply
Current is same as Live wire
Earth wire
Yellow/green in colour
Connected to metal part of appliance
In case of an electric fault, this provides a path of negligible resistance channeling the current down to Earth, protecting from electrocution
Cartridge fuse
If the appliance short circuits, and the current exceeds the rating
It will melt and cut off the electrical supply
Cord grip
Holds live wire down
In case of electric fault, live wire does not touch the appliance, preventing it from becoming live
Digestive
Food is made up of large, insoluble molecules like lipids, proteins, and carbohydrates
Need to be digested and broken down into smaller, simpler, soluble molecules
To be absorbed into the bloodstream and used by the body
PROCESS
MOUTH
Food is broken down into smaller pieces by chewing
Teeth cut and crush the food into smaller pieces for swallowing
SALIVARY GLANDS
Food is mixed with saliva produced here
Saliva is a digestive juice containing digestive enzymes like
CARBOHYDRASE
Carbohydrase digestion begins in the mouth, oesophagus, and small intestine, breaking down complex sugars like glycogen into simpler sugars like glucose for energy
OESOPHAGUS
After swallowing, food enters and moves down this muscular tube
No secretion of digestive juices/enzymes
Carbohydrase in saliva continues to digest the food as it is moved down into the stomach
STOMACH
Muscles in the stomach wall contract to churn and mix the food
Food is mixed with more digestive juices like
PROTEASE
and acid like
HYDROCHLORIC ACID
PROTEASE
Break down proteins into polypeptides and amino acids, continuing to small intestine
ACIDS
Kills harmful microorganisms swallowed along with the food
Provide an optimum pH for digestive enzymes in the stomach to work
SMALL INTESTINE
Digestive juices containing numerous digestive enzymes like lipases, proteases and carbohydrases are added
Proteins, lipids and carbohydrates are completely digested here
Smaller, simpler, soluble nutrient molecules are diffused through the intestinal walls into the bloodstream
ABSORPTION OF FOOD
Small nutrient molecules produced during digestion pass into the bloodstream through the wall of the small intestine
Molecules are then transported to where they are needed in the body
Only small, simple, soluble molecules can pass through the wall of the small intestine
Large, insoluble molecules cannot pass through the wall of the small intestine
STRUCTURAL ADAPTATIONS
Folded inner lining of the small intestine over 5 metres long is covered with fingerlike projections called villi
Increase surface area of small intestine
Maximise the rate of nutrient absorption through diffusion
Villus walls are only 1 cell thick allowing faster diffusion due to the shorter distance
Vessels called lacteals absorb fatty acids and glycerols, which are transported in lymph fluid before passing into the bloodstream
Rich network of blood capillaries to absorb simple sugars, amino acids, and other nutrients which are carried in the blood to the liver
Nutrients absorbed into the bloodstream through a combination of diffusion and active transport
Removing these substances quickly means a low concentration in the blood, allowing diffusion to occur faster
LIVER
Produces bile, which it releases into the small intestine to emulsify lipids, making it easier for digestive enzymes like
LIPASES
to digest them
Lipids digestion begins in the small intestine
Lipases break down lipids into fatty acids and glycerol molecules
Lipids are used for storing energy and insulation
Bile is stored in the
GALLBLADDER
Enzymes in small intestine work best in alkaline conditions
Food arrives from the stomach too acidic
Key Effects of Bile
Neutralises the acid by providing the alkaline conditions needed for digestion
Emulsifies fat droplets, with the bile salts breaking them up into hundreds of smaller droplets, increasing the surface area for digestive enzymes like lipases to work on, making digestion easier
LARGE INTESTINE
Water from the undigested food is absorbed into the bloodstream
Water is also absorbed in the small intestine
A mass of undigested food called faeces is left
RECTUM
Faeces is stored here until egestion
ANUS
A muscular ring through which faeces is egested out of the body during waste excretion
ENZYMES
Proteins that organisms produce to speed up chemical reactions like digestion/photosynthesis
Some break down large substrate molecules into smaller ones
Some join smaller molecules to form larger ones
Biological catalysts which are chemicals that change the rate of a reaction without being changed themselves
Lock and key model
Each has a unique shape that fits a specific substrate, a chemical changed by the enzyme
Each enzyme type can only catalyze 1 reaction so the substrate has to fit in the enzyme's active site
PROCESS
The enzyme acts on a molecule called a substrate
Enzymes and substrates have shapes that complement one another
Enzymes' unique shape allows it to form a temporary bond with the substrates
The substrates will react with one another
The substrate will fit into the enzymes' active site
Substrates will combine to form a larger product
The newer larger product will separate from the enzyme
The enzyme is unchanged at the end of the reaction and is reused over and over again
ENRICHED/ADVANCED
PERISTALIS
Food moved through the digestive system / alimentary canal through this
Muscles in the walls of the oesophagus and small intestines contract to make them squeeze
Waves of contraction sweep through the digestive system to move the food along
TEETH
Canines are pointed for piercing and tearing the food
Premolars and molars have flat surfaces for crushing and grinding
Incisors are chisel-shaped for biting and cutting
ASSIMILATION
Movement of digested food molecules into the cells where they are used
Glucose diffuses into body cells to be used for respiration to release energy
Role of Liver in Assimilation
Concerts excess glucose into glycogen, a complex carbohydrate found in humans and animals
Glycogen is stored until additional energy is required when it is converted back into glucose
Converts excess amino acids into carbohydrates and fats, producing a waste product called urea
Removed from the bodies by the kidneys
Negative Events in Malfunctions
Nausea
Increased risk of mouth and throat cancer
Severe tooth decay
Stomach ulcer
Liver damage
Respiratory
Respiration
Breakdown of food substances using oxygen with the release of energy in living cells
Why do we respire?
Energy from food is needed to sustain life for organisms to move, grow, excrete, and reproduce
To use the energy available in food, living things need to break down the food molecules through a process called oxidation
Oxidation of food molecules to release energy is called respiration
Where does Respiration occur?
Aerobic respiration occurs mainly in the mitochondria of all cells.
TYPES
Aerobic
Breakdown of food substances in the presence of oxygen with the release of a large amount of energy
Glucose + Oxygen --> Large amount of Energy released + Carbon Dioxide + Water
C6H12O6 + 6O2 --> Energy + 6CO2 + 6H2O
Energy-consuming processes in organisms
Synthesis/formation of proteins from amino acids
Cell division
Muscle contractions like heartbeats and respiratory movement
Transmission of nerve impulses of messages
Carbon dioxide and water and waste products
16.1kJ/g glucose
Experiments
Purpose of potassium hydroxide in Flask A
Removes carbon dioxide entering Flask B
Purpose of limewater in Flask B
Testing for the presence of carbon dioxide
If carbon dioxide is absent, a white precipitate will not be produced in limewater
Air entering Flask C does not contain carbon dioxide
Any carbon dioxide detected in Flask D would be solely due to the respiration from living things
Anaerobic
Breakdown of food substances in the absence of oxygen
Releases less energy than aerobic respiration
Alcoholic Fermentation (Yeast Cells)
Yeast respires aerobically in the presence of oxygen but respires anaerobically in the absence of oxygen
Yeast releases ethanol/alcohol and carbon dioxide as waste products
Glucose --> Ethanol + Carbon Dioxide + Small amount of Energy released
C6H12O6 --> 2C2H5OH + 2CO2 + Small amount of Energy released
1.17kJ/g glucose
Lactic Acid Formation (Human Muscles)
Occurs in muscles when there is not enough oxygen reaching the cells to convert all the glucose to carbon dioxide and water (waste products)
Glucose is partially broken down without oxygen into lactic acid with only some energy released
When the lactic acid is produced
Carried away from the muscle by the circulatory system
Subsequently broken down into carbon dioxide and water waste products
Glucose --> Lactic acid + Small amount of Energy released
C6H12O6 --> 2 C6H6O3 + Small amount of Energy released
Exercise
Muscle tissues contract vigorously to enable movement
Respiratory rate and heart rate increase to enable more oxygen to reach the muscle tissue
If the increased oxygen intake is unable to meet the oxygen demand, anaerobic respiration occurs to provide the additional energy required
Results in the accumulation of lactic acid in muscle cells, which incurs an oxygen debt
Can cause muscular pain and fatigue, but current research suggest this may not be true
Occurs only in certain types of cells
Muscle (lactic acid)
Yeast (ethanol/alcohol)
Bacteria
Experiment
Before the glucose solution is used, it is boiled and cooled
Boiling removes dissolved oxygen from the solution
Cooling prevents the enzymes in yeast that are required for respiration from denaturing
A layer of oil placed on top of the glucose-yeast suspension
To prevent oxygen from dissolving into the suspension
Due to the limited oxygen available to the yeast, it undergoes anaerobic respiration
If carbon dioxide is released, a white precipitate will be formed in limewater
ATP
Energy released during cellular respiration is stored in a small molecule called adenosine triphosphate
Main energy currency used in all living things
Energy is released when a phosphate bond is broken
Adenosine triphosphate is converted into adenosine diphosphate (ADP)
Gaseous Exchange in Humans
Breathing
Involves an exchange of gases between the air in the lungs and the surrounding environment air
Inspiration
Breathing in
Expiration
Breathing out
Exhaled air
Air that is breathed out
Lower concentration of oxygen
Higher concentration of carbon dioxide
Higher concentration of water vapour
Higher temperature at body temperature
Composition
16% oxygen
4% carbon dioxide
Inhaled air
Air that is breathed in
Higher concentration of oxygen
Lower concentration of carbon dioxide
Lower concentration of water vapour
Lower temperature at surrounding air temperature
Composition
20% oxygen
0.04% carbon dioxide
PROCESS
Air is inspired in
NOSTRILS
Has projecting nasal hairs to filter out dust and debris from the inhaled air
Passes through mucous membrane
NASAL CAVITY
Divided by a septum and lined by a ciliated epithelium
Mucous film traps debris and is moved to the pharynx to be spat out or swallowed
MUCOUS MEMBRANE
Blood vessels below the epithelium warm and moisturize the air
PHARYNX
Warms, moisturises, filters the air from the nasal cavity
Air and food passages (respiratory and digestive tracts) cross here
OESOPHAGUS
EPIGLOTTIS
Elastic flap at the entrance to the trachea
GLOTTIS
Guarded by the epiglottis
Opens at all times except when swallowing
Prevents air from going into oesophagus
LARYNX
Air enters it through the glottis
Contains vocal chords that we use to speak
TRACHEA
Cylindrical tube supported by rings of cartilage
Layer of ciliated, mucous secreting cells trap debris and sweep them upwards to the mouth
Divides to form 2 bronchi
C-shaped cartilage rings keep the trachea open
Tough bands of cartilage surrounding the trachea, stop it from collapsing during breathing
BRONCHUS (2 BRONCHI)
Divides into smaller tubes called bronchioles
Lungs
Right
Larger
3 lobes
Left
Smaller
2 lobes
Enclosed in
Pleural membranes
Pleural fluid
External intercostal muscles
Internal intercostal muscles
BRONCHIOLES
End in microscopic pouches/air sacs called alveoli where gaseous exchange occurs
Smallest ones are even narrower than a strand of hair
ALVEOLI
Exchange of gases takes place here between gases inside the alveoli and the blood
OXYGEN
More oxygen in the alveoli cavity
Due to the concentration gradient, oxygen diffuses into the thin film of moisture on the wall of alveoli
Oxygen diffuses into the blood
CARBON DIOXIDE
More carbon dioxide in the blood
Due to the concentration gradient, carbon dioxide diffuses into the thin film of moisture on the wall of alveoli
Carbon dioxide diffuses into the alveoli cavity
Adaptations
Mucous Membrane
Helps to warm and moisten air before it enters the lungs
Filters out bacteria
Protect lungs from infection
Cilia
Microscopic hair-like structures which continuously beat upwards and sweeps mucus laden with dust and microorganisms particles up to the pharynx
Mucus
Traps most dust and bacteria particles in the air
Trachea and bronchi lined with cells releasing mucus
Alveoli
Large surface area
Millions of alveoli
Layer of water
On the walls of alveoli
Dissolves gases for exchange
Thin walls
1 cell thick
Quick and easy diffusion
Capillaries
Richly supplied with blood
For rapid transport of gases
Physical Process
Controlled by a set of muscles working together to make the volume of the chest/thorax increase/decrease, making air move in and out of it
Inhalation (Breathing in)
Outer set of muscles between the ribs, the external intercostal muscles contract, making the ribs move upward and outward.
Muscles of diaphragm, a sheet of muscle contracts, flattening and pulling the dome-shaped diaphragm down
Volume of chest cavity increases, causing the pressure inside to fall below the pressure outside the lungs, causing air to be drawn inside
Exhalation (Breathing out)
Inner set of muscles between the ribs, the inner intercostal muscles contract, causing the ribcage to move downwards
Muscles of the diaphragm relaxes and it springs back upwards
Volume of chest cavity decreases, causing the pressure inside to rise above the pressure outside the lungs, causing air to be forced out
Effect of Exercise
During exercise, a person breathes more rapidly and more deeply.
Extra oxygen is used to meet the increased respiration demands in the muscle cells
For a person at rest, the volume of air that moves in and out of the lungs is around 500 cm3
Increase in
Volume of air breathed in and out
Rate of breathing
Faster breathing due to more breaths per minute
Residual volume of air is the air that is left in the lungs after exhalation
Measuring breathing rate
Counting the number of breaths taken in per 1 minute during rest
Typical resting respiratory rate for a healthy adult is 12-18 breaths per minute
Count the number of breaths taken in per 1 minute during exercise
Faster and more intense
More oxygen to be taken into the body and more carbon dioxide to be removed
Gaseous Exchange in Fish
Gills are gaseous exchange surfaces
Made up of many gill filaments
Increase surface area for gaseous exchange by diffusion
Comparable to numerous alveoli in the lungs increasing gaseous exchange surface area in humans
Efficient blood supply network helps to increase diffusion
Transport
Human
Why do organisms need transport systems?
Cells need a continuous supply of oxygen and nutrients
Cells produce waste products that need to be removed from the body
Complex organisms have millions of cells
Most cells are far away from the environment and cannot get materials directly from it
Transport systems needed to transport substances to and away from the cells
How does it work? - PARTS
Main transport system in the human body is the Circulatory System
Made up of 3 parts
BLOOD
Blood Plasma (55%)
Pale yellow liquid component of blood
90% water
10% dissolved minerals, proteins, nutrients, waste products, clotting factors, hormones
Medium of transport of nutrients like glucose and amino acids, waste products like urea and carbon dioxide, minerals, vitamins, proteins like albumin and globulin, and clotting factors
Transports red blood cells, white blood cells, platelets
Red Blood Cells
Transport oxygen from lungs, to the heart, and then to the rest of the body
Adaptation
Flattened
Biconcave
Increased surface area to volume ratio for faster diffusion of oxygen into cell/carbon dioxide out
Does not have a nucleus
More space for haemoglobin to bind to oxygen more effectively and faster, maximising oxygen-carrying capacity
1 more item...
Contains haemoglobin, an iron containing protein
Haemoglobin + Oxygen (at alveoli in the lungs) --> Oxyhaemoglobin (bright red colour)
Oxyhaemoglobin - Oxygen (at tissue cells/capillaries) --> Haemoglobin (dark red colour)
Flexibility
Small, flexible shape to squeeze through narrow blood capillaries to deliver oxygen to tissue cells
Suspended in plasma
White Blood Cells (Leukocytes)
Several varieties
Eosinophils
Lymphocyte
Monocyte
Functions
Destroy foreign particles (bacteria, virus)
Produce antibodies to neutralise harmful toxins
Crucial for our immune systems
Fight diseases and infections
Larger than red blood cells
Contain a nucleus unlike red blood cells
Flexible membrane
Allow them to change shape and squeeze through blood vessel walls to reach infection sites
Phagocytes
Adapted to engulf and digest pathogens, cellular debris
Flexible membrane extends to surround and absorb the foreign invading particles
Lymphocytes
Produce chemicals called antibodies to attack pathogens
Platelets
Small, irregular fragments of cytoplasm
Not true cells
Function
Blood clotting
Prevent excessive blood loss
Release of clotting factors
Store and release chemicals that activate a cascade of reactions
Leads to a formation of a protein mesh called fibrin, strengthening the plug to form a stable clot
Sticky surface
Platelets adhere to injury sites when a blood vessel is damaged, form a temporary plug
Small size due to lack of nucleus
Easily transported to injury sites
Tissue Fluid
Formed by blood plasma that leaks out via gaps and fills up the space between the body cells
Carries substances between the blood and body tissues
Exchange of Materials
Capillaries to Tissue Cells
Oxygen
Digested food
Tissue Cells to Capillaries
Carbon dioxide
Waste substances
All through
DIFFUSION (main)
(sometimes osmosis)
HEART
Pathway of Blood
Lungs for oxygenation
Pulmonary vein to the heart
Left atrium relaxes, blood enters
1 more item...
Heart Attack
Natural pacemakers
Specialised muscle cells in the right atrium send electrical impulses to the left atrium and ventricles, making them contract to pump blood
If the heart's natural pacemaker stops working, an artificial pacemaker, a small battery operated device is implanted in the chest to correct the irregular heartbeat
Coronary arteries
Supply heart muscle with oxygenated blood and nutrients
If blocked, the heart may become starved of oxygen, resulting in a heart attack
Septum
Divides left and right
Prevents oxygenated and deoxygenated blood from mixing together
Pericardium
Outer part of the heart
BLOOD VESSELS
Blood circulates through the circulatory system through a network of pipes/tubes
TYPES
Arteries
Carry oxygenated blood away from the heart
Except pulmonary artery which carries deoxygenated blood from heart to lungs
Structural features
Muscles, elastic fibers in the arterial walls make them strong and elastic
2 more items...
Have a small lumen
Branch into a network of smaller vessels called arterioles, then into capillaries
Pulse
Rhythmic expansion and recoil of arteries can be felt as a pulse
Veins
Carry deoxygenated blood back to the heart
Except pulmonary vein which carries oxygenated blood from the lungs to the heart
Structural features
Very few muscles in the vein walls
Relatively large lumen
Usually contain 1-way valves
2 more items...
Venules, the smallest veins, collect deoxygenated blood from the capillaries and connect to veins
Skeletal muscle pump
Contraction of surrounding skeletal muscles pushes deoxygenated blood back to heart
Capillaries
Allow exchange of materials between blood and body cells via
DIFFUSION
(and sometimes osmosis)
Tiniest blood vessels in the body
Digested food and oxygen are diffused from the capillaries into the tissue cells
Carbon dioxide and other waste substances are diffused from the tissue cells into the capillaries
Structural feature
1 more item...
Highest number of blood vessels exist in this type (most common type)
Connect arteries and veins
Slow moving, low pressure blood, to allow ample time for substance exchange
STRUCTURE
Tunica externa
Tunica media
Tunica intima
External elastic membrane
Smooth muscle
Internal elastic membrane
Lumen
Endothelium
Fibrous tissue for protection, support, strength
All 3 parts must work together for the whole system to work properly
If 1 part does not function properly, the whole system will be affected
Works with other body systems
Food passes from the digestive system into the blood
Oxygen is taken into the lungs and enters the blood
Circulatory system carries food and oxygen to all body cells
Types of Circulatory Systems
Double
Humans and other mammals
Blood passes through the heart twice
1st circuit
Heart and lungs
2nd circuit
Heart and tissue cells
Single
Some animals like fish
Gills to tissue cells to heart to gills
Negative Events in Malfunctions
Irregular heartbeat
Increased heart rate
Increased blood pressure
Increased risk of heart attack
Increased risk of stroke
Narrowed arteries resulting in reduced blood flow to the limbs and muscles
Plant
Transport system in flowering plants is to carry water, minerals, nutrients to all cells
Made up of vessels in the roots, stems, leaves
Xylem and phloem work together to ensure that all cells in the plant receive the necessary sugar, water and minerals to survive
XYLEM
Roots have specialised cells called root hair cells
Long and thin to increase surface area for absorption of water and minerals
Water enters the root hair cells from the soil by osmosis
Dissolved minerals enter the root hair cells from the soil by diffusion
Covered in a layer of cells called the epidermis
Extensions of the epidermis cells
After getting absorbed by the roots, the water and minerals pass through a cortex, then into the xylem located in the stem
The water then gets transported to all parts of the plant, including the leaves for photosynthesis
Made up of dead cells with no cytoplasm that have joined together to form a continuous pipe for liquid to flow through
Movement of water upwards is called the transpiration stream
Transpirational pull generated by negative pressure from the evaporation of water from leaves through the stomata
Cohesion between water molecules and diffusion work together to pull the water up
PROCESS
Carbon dioxide diffuses out of the stomata, while oxygen diffuses in
Leaves containing spongy mesophyll cells are covered in a film of moisture
When this moisture evaporates, it diffuses out of the stomata
This loss of water from the leaves pulls more water up these tubes, replacing the lost moisture
Root hair cells absorb water through osmosis and mineral salts through diffusion to be transported up
Water moves in only 1 direction upwards, from the roots through the stem and to the leaves
Cell walls are impermeable and watertight, made from a strong substance called lignin providing support to the plant
How is the water absorbed through the root hair cells?
Apoplastic pathway
Travels through spaces between cell walls
Symplastic pathway
Travels across cells and cytoplasms
Experiment
A xylem tube is narrower than a strand of hair
Place celery in a jar of coloured water and let it stand for a day
Coloured water moves upward through the xylem to the leaves
Xylem tissue turns coloured, revealing the position of the vascular bundles in the stem
Leaves are stained blue
Wilting
Water pulled upward from the roots to the stem and leaves
Lack of water causes vacuoles in cells in the plant to shrink
Lack of pressure on the cell walls to keep the plant upright, causing it to wilt
PHLOEM
Made up of living cells that form a continuous pipe for substances to flow through
Consist of tubes with small holes in the end walls, which are structures called sieve plates
Allow dissolved sugars produced during photosynthesis to pass through the cell walls
Substances move in both directions, which is called translocation
Caused by a pressure gradient
Transport of food (sugar - sucrose, amino acids) produced during photosynthesis
VASCULAR BUNDLE
Xylems and phloems form combined structures called vascular bundles
Position of these vascular bundles varies roots, stems, and leaves
STEM
Vascular bundle arranged around its outer edge, providing the stem with structural support
Between the pith (middle) and the epidermis (edge)
LEAVES
Vascular bundles form a network of veins that help support the leaf's softer tissues
Between the upper and lower epidermis (centre)
ROOTS
Vascular bundles arranged in the middle
Xylem in the middle, phloem around it
XYLEM VS PHLOEM
XYLEM
Dead cells
Thick
Rigid lignin
Impermeable
None
1 more item...
PHLOEM
Living cells
Thin
Cellulose
Permeable
Lining
1 more item...
COMPONENT
What is it made up of?
How thick is the cell wall?
What is the cell wall made up of?
Permeability
Cytoplasm
1 more item...