B2 - Organisation
Principles of organisation
Cells tissues and organs
muscular tissue: force and motion
mesophyll: photosynthesis
epidermal tissue: skin, and the waxy covering of plants
epithermal tissue: lines outer surface of organs
Organ systems
digestive system
stomach
epithelial tissue: lines the stomach
Cells
Building blocks of life
muscular tissue: moves contents or stomach
Large intestine: absorbs water from undigested food
small intestine: digests food and absorbs soluble food molecules
glands: produce digestive enzymes
Glandular tissue:produces digestive juices that break down food
Liver: produces bile
Enzymes
Active site: binds to substrate, only fit specific ones: "lock and key"
Proteins, biological catalysts
if denatured, it means active site has changed shape, can no longer produce a reaction
enzyme reaction
factors
temperature
rate of reaction = change in mass / change in time
pH
digestion
breakdown large food molecules
main enzymes
amylase: breaks down starch into simple sugars,
protease: make amino acids (from proteins)
lipase: lipids to fatty acids + glycerol
bile
emulsification: turning fat into small droplets
works coz smaller fat drops have a higher surface area than the original fat drop which increases the rate of the lipase-catalysed reactions that break down fats
alkaline so neutralises stomach acids so the enzymes in the small intestine can operate at the optimum pH
stored in gall bladder
made in pancreas, salivary glands
actions sites: mouth, small intestine
action sites: small intestine, stomach
made in pancreas, stomach
made in small intestine, pancreas
tests for food molecules
proteins: biuret, will turn purple
sugar: benedict's + heat, will turn green, yellow or red
starch: iodine, will go blue-black
lipids: ethanol, shake, cloudy emulsion
Circulatory System
Blood vessels
capillaries
arteries
veins
elastic fibres in walls
thick muscles in walls
Arteries take blood Away from the heart
smaller arteries, pass close to body cells
waste products like CO2 move out the cells and into the blood, food and oxygen moves from blood to cells
thin walls
thinner walls than arteries
organs to heart
have valves which stop back flow of blood
low pressure in blood so wider cross-section
heart
structure
four chambers: the left and right atria and the left and right ventricles.
also contains valves and a pacemaker
Blood entering the heart through the right atrium is deoxygenated and comes from the body. Blood entering the heart through the left atrium is oxygenated and comes from the lungs.
pacemaker is a group of cells in the right atrium, controlling the pumping of the heart
when the heart beats, 1. blood enters the heart via the atria, 2.atria contract, forcing blood down into the ventricles below, 3. ventricles contract which forces blood to exit the heart
important veins and arteries
pulmonary vein transports oxygenated blood from lungs to heart
pulmonary artery transports de-oxygenated blood from heart to lungs
coronary arteries: the coronary arteries supply the heart muscle with oxygenated blood
aorta:heart pumps out oxygenated blood to the body
vena cava:heart receives deoxygenated blood from the body through this
circulatory system & gas exchange
double circulatory system in humans
1) deoxygenated blood enters right atrium 2) blood is pumped to the lungs by the right ventricle 3) lungs oxygenate blood 4)blood returns to left atrium 5) blood pumped to body by left ventricle 6) blood return to heart after deoxygenation
alveoli: large surface area, good blood supply(surrounded by capillaries), close to capillaries
blood
a tissue, made up of plasma fluid
white blood cells
ALWAYS SAY SUSPENDED IN PLASMA
red blood cells
platelets
no nucleus, responsible for triggering blood clotting at wound sites
haemoglobin binds with then carries the oxygen from lungs to the body cells and used for respiration
Biconcave shape
small, can pass through capillaries
no nucleus to free up more room for oxygen
have a nucleus
can chnage shapet to squeeze through walls of blood vessels into tissues to engulf harmful microorganisms
left ventricle has thickest walls
non-communicable diseases
health
contributions to ill health: disease, diet, stress, life situations
disease interaction: different diseases can interact with each other leading to a spiral of declining health
physical problems can greatly impact upon a person's mental health
a disease that suppresses the immune system can make people more susceptible to catching different diseases
viruses copying cells can stimulate cancers
allergies can be triggered by an immune reaction to a pathogen
sampling: tracking diseases to inform their policy decisions
if big population, lower sample size, e.g. only sample every, 10 people
Health is defined as a state of physical and mental well-being
risk factors: factors that increase the probability of developing a disease
substances
lifestyle
causal mechanisms
smoking --> lung disease
smoking during pregnancy --> low weight of babies
excessive alcohol --> liver and brain damage
poor life style --> cardiovascular disease
obesity --> type 2 diabetes
exposure to radiation --> cancer
excessive alcohol consumption whilst pregnant --> brain damage in babies
unavoidable
genetics
age
heart diseases
communicable: can spread, non communicable: can't spread
coronary heart disease
coronary arteries narrow because of a build up of fatty deposits, this reduces blood flow and causes a lack of oxygen supplied to the heart
non-communicable
heart valve disease
Leaky valves allow backflow of blood, forces heart to do more work to circulate the same volume of blood, which puts a strain on the heart.
valves that don't open fully can obstruct blood flow, greater force, added strain on heart.
fixing faulty valves
animal or artificial valves can be inserted, major surgery, can cause blood clots
treatment
artificial heart
unlikely to be rejected by immune system
artificial hearts can also be used to provide the heart with some rest to allow for recovery
can result in long expensive hospital stays
can cause blood clotting which can permanently lead to strokes
heart transplants
if no donor organs, patients use artificial heart until donor arrives
treatment
statins are drugs that can be taken to decrease cholesterol levels, causing less fatty materials, less fatty deposits. have side effects
stents: inserted in order to keep coronary arteries open. can close up again because of irritation and build up of scar tissue. drugs must be taken to prevent blood clotting
cancer
tumour types
malignant tumours: can spread, creating secondary tumours
benign:can't spread, harmless
risk factors
genetics
lifestyle
changes in cells lead to uncontrolled growth and division of cells
Plant Tissues, Organs & Systems
Plant Organs
reproductive structures
stems
leaves
roots
palisade mesophyll: below upper epidermis, exposed to alot of sunlight, lots of chloroplasts
stomata: found in lower epidermis, gaps between guard cells, used for diffusion of gases in and out of the leaf
spongy mesophyll: contains air spaces, help with gas exchange
epidermal tissue: covers outside of leaf as well as rest of plant
Transpiration
root hair cells absorb water from soil via osmosis, mineral ions are taken up by active transport
xylem vessels carry up the stem and into the leaves
leaves; evaporates and diffuses out through stomata <--- transpiration
factors: light intensity, humidity, temperature
potometer is used to calculate and estimate of the rate of transpiration
Translocation
Phloem: made up of columns of elngated cells that have holes in their end walls which allow cell sap to pass between cells
bidirectional
dissolved sugars movement, produced in photosynthesis
Tissues
Xylem cells are DEAD so they have a low resistance to water. they have no end walls. LIGNIN helps strengthen and water proof cells
root hair cells: lots of mitochondria for active transport, long projections for large surface area
Stomata
Guard Cells open the stomata by taking up water and swelling (and vice verca)
when there is lots of water, the plant opens stomata to allow gases to move in and out of leaf. when there is no water, they close to prevent further water loss
close at night because gases not required for photosynthesis so preserving water
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