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Hii!! so this is gonna be a series I'm going to do more for myself than anyone else where I practice explaining IGCSE topics in an easy ish way to try convince myself I understand. However I hope it's also able to help procrastinating students on spacehey
It's a study method I use to just wrap my head around complicated subjects by basically teaching it. If you could ask questions below that would be great help in testing me!!
basically I'm making sure im locked in wherever I try to slack off ╥﹏╥
note: I will be updating this for each topic I add!! and will announce on my bulletin cus am annoying
Section 1: Biology
Lungs and shit
1) respiration
okay divas your lungs are used for RESPIRATION aka breathing. "erm acktually they aren't the same thing-" SHUT THE FUCK UP (they aren't)
Respiration is basically a bunch of chemical reactions that break down nutrient molecules (nutrient molecules are things like glucose - the only one you really need to know for the exam) for energy
it takes place in living cells in ur bodyyy
HERE IS THE EQUATION: C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy (as ATP)
glucose + oxygen ---> carbon dioxide + water + energy
in PLANTS it happens in the mitochondria - which is why it's called "the power house of the cell" (if i catch any of yall writing that in ur exam I'm gonna beat you)
then there is Anaerobic Respiration
whats the difference?
Think of it as respiration's broke ass cousin who can't afford oxygen
Anaerobic Respiration is the release of a little energy from each molecule of glucose without oxygen - so you'd need it when exercising
There is two types of anaerobic respiration: Lactic Acid Fermentation and Alcoholic Fermentation (not beer)
Lactic Acid Fermentation happen in ur mooscles and the equation is relatively simple sugar:
C6H12O6 ---> 2C3H6O3 + energy
glucose ----> Lactic acid + energy
Youre lactating all over the place you freak (ಠ_ಠ)
so we have the energy is good but the one disadvantage of this is that lactic acid can build up in ur muscles while exercising so BREATHE BRO BREATHE
You're heart pumps like crazy when working out to get oxygen to the muscles for them to respire, to send more glucose to the muscles too and to remove CO2 and lactic acid
Alcoholic Fermentation is a little harder. To tell the difference between the two fermentations, remember alcohol has CO2:
All Alcohol
Furries Fermentation
Have Has
Collars CO2 (carbon dioxide)
and
Leashes Lactic
After Acid
Feeling Fermentation
Down Doesn't
Keep those furries happy
Alcohol Fermentation is from yeast
ALCOHOL FERMENTATION FORMULA: C6H12O6 ---> 2C2H5OH + CO2 + Energy
glucose ---> ethanol + carbon dioxide + energy
Quick recap:
Respiration is when the cells do have oxygen to make energy
Anaerobic Respiration uses glucose to make energy when there is no oxygen with fermentation of alcohol and lactic acid
2) Gas Exchange
what the freak
Oki doki (just monika) so these are the lungs and the photo on the right is alveoli which is where gas exchange takes place
Gas exchange is the exchange of oxygen and carbon dioxide between an organism or cell and the environment
Bronchus branches into Bronchioles which have alveoli at the end of it
Alveoli are in the Alveolar Sac. They are covered in blood capillaries and are shaped like little grape bunch, yummers ( ´﹀` ) 🍇
this grape shape is there to increase surface area and usually the walls of the alveoli are one cell thin to allow diffusion of CO2 from the blood into the alveoli, as oxygen (O2) is diffused into the blood stream
like a trade off:
Goblet Cells create mucus to protect your Trachea and keep it clean - the protective mucus traps pathogens (diseases) for cilia (tiny microscopic hairs) to push out
Trachea can't stand on it's own so the rings of cartilage hold it up and withstand the pressure - kinda co-dependent if you ask me but whatever makes you happy girl 💔
Shitting
Excretion is the process is which metabolic waste is eliminated in excess from an organism
Metabolic waste includes:
> Sweat (releases water, urea and toxins in low quantity)
> Carbon Dioxide - CO2
> Piss (releases water, urea and salts in large quantities)
Pooping is NOT metabolic waste because it's egested - it's created through the alimentary canal (passage along which food passes through the body from mouth to anus) without being digested
Liver
Deamination is the breaking down of amino acids molecules, that can't be used, into two new molecules
The first new molecule is broken down into a fat or carbohydrate to be stored and used for energy. The other molecule would be NH3 which would combine with CO2 to make urea, the excretory product
So the liver filters the blood
Kidney
The kidneys then "clean" the blood by removing the urea, adjusting ions pH and adjusting the water content
It's able to do this because your kidney has a million little filter units called nephrons that make urine when removing the waste from the blood
Nephrons are surrounded by capillaries to exchange the clean blood back out into the blood stream
It looks awful but syllabus doesn't require you to know too much (unlike our fuckass sub that made us go over EVERYTHING)
Syllabus: "(a) the role of the glomerulus in the filtration from the blood of water, glucose, urea and ions
(b) the role of the nephron in the reabsorption of all of the glucose, some of the ions and most of the water back into the blood
(c) the formation of urine containing urea, excess water and excess ions
(details of these processes are not required)"
So let's go over those points:
(a)
The large blood vessels in nephrons get separated into capillaries called the Glomerulus
These capillaries (the glomerulus) are all stuffed into the small head of the nephron called the bowman's capsule which creates a high pressure due to the tight space
Diffusion pushes water, salt, glucose and urea (the filtrate) into the bowman's capsule before 65% of it is reabsorbed in the proximal tubule through active transport
(b)
idk what it's specifically asking babe but i searched on google and it said this:
"Nearly all of the filtered glucose is reabsorbed back into the bloodstream through the proximal tubule of the nephron"
(c)
So the distal tubule is the last part of the filtering in the nephrons before the connecting duct
The distal tubule regulates the pH by "regulation of potassium and sodium chloride."
Basically it absorbs K+ (potassium) and H+ (hydrogen) ions while pushing out NaCl (sodium chloride), HCO3 (hydrogen carbonate) and H2O (water) ions
The collecting duct collects urine from the nephrons and moves it into the renal pelvis and ureters. It pushes out NaCl, H2O and urea
So pee is just made of urea, chloride, sodium, potassium, ammonia, creatinine and other dissolved ions, and inorganic and organic compounds
Urine is:
> 95% water
> 2% urea
> 2.8% dissolved salts and other ions
> 0.2% creatine, ammonia and uric acids
Anything that affects your water intake will affect your piss colour
less water = darker pee
more water = lighter pee
Exercising and temperature causes darker pee as you loose water when you sweat (less water)
Kidney Issues
Kidney failure is when nephrons will stop working efficiently due to an infection or an accident
Stages of kidney failure:
Normal function --> mild loss of function --> moderate loss --> severe loss --> kidney failure
This can be treated with a kidney transplant or a kidney dialysis (how dialysis works was removed from the curriculum)
a kidney transplant is the transfer of a healthy kidney from a person called the donor to another person being the recipient
There is a risk of tissue rejection which is when a recipient's immune system will attack the donor kidney and destroy it
Advantages: Disadvantages:
> Simple > shortage of organs
> Cheaper long term > donor kidney only lasts 8 - 9 years
> Higher quality of life > needs immune suppressants
Ribs and air composition
You breathe in CO2, O2, nitrogen and water vapour
(still doesn't explain ur stank ass breath)
CO2 in: 0.04%
CO2 out: 4%
O2 in: 21%
O2 out: 17%
N2 in: 78%
N2 out: 78%
water vapour in: low
water vapour out: high
Muscles in your ribs are arranged in layers called internal and external intercostal muscles
When you breathe in: your external intercostal muscles contract making the internal ones relax, your ribcage moves up and outwards, your diaphragm pushes down and the volume of your thorax increases
think of it like your chest making room for the air by expanding, like inflation 😋
When you breathe out: your internal intercostal muscles contract making the external ones relax, ribs move in and down, your diaphragm comes back up, and the volume of your thorax decreases
like your chest is shrinking back in
Neurons
Stimulus is a thing/event that evokes a specific functional reaction in an organ/tissue due to changes in an organism's environment
Receptors are meant to detect stimuli and send electric signals to the brain about it. An organism will then respond to the receptors with effectors
Examples of an effector are: glands and muscles
Most animals have 2 was of sending messages between effectors and receptors: 1) through nerves and neurons in the nervous system 2) through hormones in the endocrine system
we gonna talk about the nervous system first:
Focus on the motor neuron for now
These neurons have long ass fibres of cytoplasm which allows them to carry messages quickly and their axon is also the longest (dream body goals tbh 😔💔)
when the dendrites on the neuron picks up a signal from the other neurons it's called a nerve impulse. All the motor neuron baddies take a hit before the impulse travels up their axon before having to pass the blunt to the next neuron
all of them have a layer of protein called myelin over their nerve fibres to insulate the neuron and to stop the nerve impulse from bouncing off elsewhere and making you tweak
Cyton - cell body - of the motor neuron is terminal (idk what that means but can you lock the fuck in please?)
The motor neuron is in the effectors (muscles and glands)
Receptors are present in the motor neuron
It has many dendrites
It has a short dendron
and it's axon is looooooooong
Types of sensory receptor neurons
> Photoreceptors - in the eyes
> Gustatory receptors - on the tongue
> Auditory receptors - ears
> Olfactory receptors - in ur nose
> Tactile receptors - in ur skin with the bugs
The cyton of the sensory neuron is on the lateral side
Sensory neurons are found in the sense organs
Receptors are present in the sensory neuron
It has no dendrites
to compensate it has one long dendron
and it's axon is short and petite
"The y/n of neurons" - Michael
Relay neurons
Their cyton/cell body is terminal
they're found in the spinal chord
Receptors are NOT present in relay neurons
It has plenty of dendrites
It has a short dendron
it has a short axon
basically the same as motor neurons but they're in the spine and have a short axon
synapse
the only context i could imagine most people (me) are familiar with the concept of synapses is if they're doing drugs
A synapse is a junction between two nerve cells consisting of a tiny gap where impulses pass by diffusion of a neurotransmitter
The gap in question is a synaptic cleft which is the small gaps between where the neurons touch tips
pretty hot right?
Those circles carrying the blue balls are called vesicles which are there to carry the neurotransmitters
When the neurotransmitters diffuse across the gap, they bind to the receptors on the other neuron which triggers the rely neuron
Reflex arc
A reflex action is a sudden, uncontrolled, and unconscious action that involves only the spinal chord and your brain only gets involved after the response. sounds like you going back to ur trashy ass man
The nerve pathway of the reflex action is called a reflex arc
Stimulus --> sensory receptor --> sensory neuron --> relay neuron --> motor neuron --> effector
Spinal Chord
It's kinda a lot to remember but I just say they're all neurons with the exception that sensory neuron also has a receptor cus she just needs to be different and ofc she's gonna go first after the stimulus that attention whore
Hormones? uhh yeah, i sure hope they do
so aside from you nervous system before, you also have the endocrine system which uses glands to send out hormones as chemical messages to specific target organs
The glands where the hormone is secreted are are usually away from the target organ butt the target organ has specific receptors on their cells for the hormones so they won't get lost in the circulatory system where they are transported
two types of glands:
1) Exocrine glands - they are duct glands and action is at the target organ
2) Endocrine glands - they are ductless glands and they are far away from the target organ so they secrete into the blood
Gland time:
Pituitary - produces growth hormone
Thyroid - produces thyroxine which helps in the metabolism or carbs, fats and proteins
Pancreas - produces insulin and glucagon which regulates blood sugar
Adrenal - produces adrenaline which is your fight or flight response
Reproductive organs - testosterone/estrogen which helps develop secondary sexual characteristics like your hair, voice, body, women develop boobs and mammary glands, men get broader shoulders and have to work for their boobs, and women get broader hips. but im only putting one of these in my roommate's food
The endocrine system may be slower than the nervous system but the effect impulse lasts longer
Homeostasis
The endocrine hormones from before help in a process called homeostasis, especially with insulin and glucagon
Homeostasis is the maintenance of constant internal environment within set limits. This includes body temp, glucose regulation and OC2 levels in the blood
The hypothalamus is an area of the brain that produces hormones that control: Body temperature, Heart rate, Hunger, Mood
Temperature regulations
The way your body controls you temperature is by using the blood flow in your blood vessels, your muscle activity/metabolism and your hair follicles
The body core temp is 36.8C
When you body is cold, your body does what's known as vasoconstriction which is the narrowing of blood vessels to slow down the flow, like a corset, in order to save heat. Other mechanisms to save/gain heat:
> Respiration increases
> Muscles work/tenses
> Surface blood vessels contract
> Hair stands up to trap oxygen between them as an insulator
Whenever your body is warm, it wants to lose heat. It does this by letting the arterioles carrying blood near the surface to dilate so more blood flows through, this allows sweat glands to make sweat. There is then less blood flowing through the shunt vessels. Other mechanisms to lose heat cus ur too hot😔😔:
> Respiration slows
> hair lies flat (hair erector muscles relax)
> sweating
> blood surface levels dilate
Homeostasis: Glucose regulation
A negative feedback loop occurs in biology when the product of a reaction leads to a decrease in that reaction
Glucose is a sugar that gets broken down during respiration for energy
Eating = glucose rise
Exercise = glucose fall
Your body controls glucose using the pancreas and the liver. The pancreas making the hormone insulin and glucagon. The liver uses those hormones to filter the glucose
Consuming glycose
1) eat carbs
2) digest - glucose gets absorbed by the small intestine
3) glucose sent through the hepatic portal vein - highest glucose concentration is here
4) Liver filters the glucose into glycogen for storage - glucagon is used to increase blood sugar
5) sent to the hepatic vein where there is slightly less glucose
6) sent to heart and brain where they use some of the glucose and send the right amounts of it to different parts of the body before sending it off to iota
7) sent to the mesenteric artery where the lowest concentration of glucose is
Too much glucose?
Insulin is secreted from the pancreas to bind to receptors of body and liver cells. This sends a signal to the liver that there is too much glucose and decreases the blood sugar levels
Too little glucose?
When the blood glucose down, 3 receptors notice: liver, muscles and pancreatic cells. Receptors send a message
The pancreatic cells will get the pancreas to make more glucagon which binds the to the liver and muscles cells.
The glucagon breaks down into glucose before being sent back into the blood stream, increasing the blood glucose level: homeostasis is maintained
Liver and muscle cells tell pancreas to stop making glucagon
Circulatory system
Circulatory system carries blood, but it also transports 6 other things:
> Heat
> Oxygen
> Nutrients
> Wate Products
> Carbon Dioxide
> Hormones
Single circulating system is a system of blood vessels with a pump that ensures a one way flow of blood - blood passes through all parts of the body in one circuit before returning to the heart
fishies have these :3
humans have a double circulating system which is when the blood passes through the heart twice to complete a full circuit of the body
1) blood gets pumped to the lungs and picks up oxygenated blood
2) blood gets taken back to the heart
3) heart pumps oxygenated blood to the rest of the body where the blood is collected
4) deoxygenated blood is sent back to the heart to get pumped to the lungs
advantages of double circulatory system: blood can flow at both low and high pressure, no mixing of oxygenated and deoxygenated blood, and allows for rapid movement of oxygen to cells and removal of waste products
Blood cells, vessels and clots
there are 3 kinds of blood vessels: arteries, veins and capillaries
Arteries carry the oxygenated blood away from the heart and to the body. Think A for Artery and A for Away from the heart.
Veins carry deoxygenated blood BACK to the heart
Capillaries are the smallest branch of the artery were oxygen in exchanged to tissues for waste products before rebranching into a vein
Artery --> Arteriole --> Capillary --> Venule --> Vein --> Heart REPEAT🔃
Artery structure:
It has a thick outer wall, a small lumen and a thick elastic wall to handle the high pressure from the oxygenated blood
Vein structure:
Thin wall containing valves, LARGE lumen holy gyatt and thin elastic tissue
Capillaries structure:
tiny lumen, one cell thick wall for gas exchange
Anything with the word "Renal" is in reference to the kidney. The renal artery bringing oxygenated blood to the kidney and the renal vein sending back deoxygenated blood
Anything with the word "Hepatic" is in reference to the liver. Hepatic vein and Hepatic artery being blood back to the heart and blood away from the heart. The hepatic portal vein is blood from the liver to the intestines, spleen, pancreas and gallbladder
Clots:
Your blood contains floating cells of plasma (yellow liquid) - it also contains proteins, sugars, salts, WBC, RBC and platelets (pieces of cytoplasm)
When you get a cut in the wall of your blood vessels, platelets change shape and stick to the wall
Platelets stick to the edges to plug the hole, but they only last 24 - 72 hours, making a clot
The plasma protein then turns fibrinogen to fibrin
Fibrin forms a mesh net over the clot - the net catches platelets and RBC to join the clot
The heart
Ts pmo 💔
Deoxygenated blood enters the vena cava and leaves by the pulmonary artery
Oxygenated blood enters the pulmonary vein from the lungs and leaves out the aorta
Cardiac muscles contract with stressful/hormonal situations
Increased heart rate is caused by: drugs, stress, exercise, and excitement
Lowered heart rate caused by: drugs, brady cardiac and good aerobic fitness
Coronary heart disease (CHD):
1) Fatty cholesterol plaque builds up over time and hardens
2) the hardened plaque cracks
3) platelets think its a cut and forms a clot around the crack
4) artery narrows even more
5) no blood flow - no oxygen to muscles
Prevention: less saturated fats and exercise
Treatment: shunt or heart transplant - one of the signs is a heart attack
ECG are ElectroCardioGraphs to measure ur heart rate
Ventricular fibrillations is when ventricles are uncoordinated , fluttering and little blood is pumped. You can shock the heart through defibrillation to restart the heart
Characteristics and classification
The factors that determine if something is considered living: MRS GREN
Movement - action by an organism causing them to change position or place
Respiration - chemical reactions in cells that breaks down molecules and release energy for metabolism
Sensitivity - ability to detect and respond to changed in internal and external environment
Growth - permanent change in dry mass and size
Reproduction - process of making more of the same organism
Excretion - removal of metabolic waste products and toxic substances from the body in excess
Nutrition - taking in of materials for growth, energy and development
5 animal kingdom:
1) animal
They are multicellular, has no cell wall or chloroplast and eats others for nutrition. They're kinda the betas for cells in the animal kingdom imo
like okay, yes girl give us nothing!!
2) plants
They are multicellular, has cell walls and chloroplasts and uses photosynthesis for nutrition. lowkey they're fucking goated
Cellulose is important - from glucose
3) Fungi
usually multicellular, has a cell wall, feed on dead on parasitic nutrition. Chill guys, i have no issues with them
4) protoctists
some multicellular, some unicellular, all have nucleus, cell wall and chloroplasts, some photosynthesis some eat living things. "Nice guys always finish last" aah cells
5) prokaryotes
all unicellular, have cell walls and cytoplasm but no nucleus or mitochondria, eats dead things. They mean well
Big backery
our body when we ingest food, our body first breaks it down through physical digestion. Its the mechanical break down of food without chemical change to the food, increasing the surface area for the enzymes to act apon. It is mainly carried out by the chewing action of the teeth, the churning action of the stomach and the emulsification of fats by bile in the duodenum.
zoinks scoob,, thats a lot of big words
Enzymes: proteins that act as biological catalyst which speeds up the rates of reaction without changing the reaction over all
Emulsification: when bile in the stomach breaks down large lipids (fats) droplets into smaller ones in the stomach. Bile is made in the liver and released through the gallblader
Duodenum: first part of the small intestine, second part is the ileum
After that, enzymes act in chemical digestion which is the break down of large insoluble into smaller ones
Stuff we need to ingest
Calcium ions for our bones, teeth and plays a role in blood clotting
Iron ions for making haemoglobin in RBC to carry oxygen around the body
Fibre ions (roughage) to help food pass through the stomach and intestines
Vitamin D to help absorb calcium for bones and teeth and prevents rickets (soft bones)
Vitamin C for healthy skin and gums. Also prevents scurvy ( wounds don't heal + excessive bleeding)
Test for vitamin C: 1 cm3 of DCPIP in solution with sample, if vitamin C is present it will turn
Blue --> colourless
Carbohydrates - we need for respiration in cells, transported as sucrose, turned into starch for storage and is turned into cellulose for plant cell walls
Glucose monomer which adds together to get, starch, maltose and sucrose polymer
Test for glucose (reducing sugars) you add benedict's solution to the sample you're testing, and heat it. If glucose is present, the solution will turn from blue --> orange or brick red
Test for starch involves iodine solution being added to the sample. If starch is present, solution will turn from orange brown --> blue black
Chemical breakdown:
Starch --- amylase ---> Maltose --- maltase ---> Glucose (simple reducing sugars)
Amylase is made in the salivary glands and pancreas. It acts in the mouth and duodenum
Maltase is produced and acts in the small intestine
Fats and oils - long time storage of energy and a layer under the skin for insulation.
Monomer is 3 fatty acids and one glycerol molecule
Test for lipids: add 2cm3 of ethanol and water, mix. If fats are present, cloudy/milky emulsion will appear
Chemical break down:
Fats and Oils --- lipase ---> Fatty Acids and Glycerol
Lipase is produced in the pancreas and acts in the duodenum
Proteins - all cells contain it, makes anti biotics, is needed for growth and repair of tissue. Only nutrient that also contains nitrogen
Amino Acid monomer and protein polymer
Test for proteins: Biuret test. If proteins are present, solution will turn blue --> violet/purple
Chemical Breakdown:
Protein --- protases ---> amino acids
Protase in acidic solution: Pepsin (produced and acts in stomach)
Protase in alkaline solution: Trypsin (produced in pancreas and acts in the duodenum)
I cant help you these tbh,, you're just gonna have to thug it out and remember these fuckass enzymes
You ingest things meaning you put substances into your body, it gets broken down in digestion. Afterwards, nutrients get absorbed into the blood by the small intestine to assimilate with the cells to be moved with the cells
Villi are these little shits on the walls of the ileum and are finger shaped to increase surface area with a thin wall for faster absorption. The capillaries absorb glucose and amino acids into the blood while the lacteals absorb fatty acids and glycerol to the lymph
Bile is stored in the gallbladder after being produced in the liver until the gallbladder busts the bile into the duodenum for it to neutralise the HCL (hydrochloric acid) from the stomach and emulsify the lipid.
HCL are one of the gastric juices in the stomach and it kills harmful microorganisms while also being the optimum pH for pepsin
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