organisation Flashcards
What is a tissue? give example
A group of similar cells that work together to carry out a particular function
muscular tissue, made up of muscle cell
What is an organ? give example
Group of different tissues that work together to perform a certain function
stomach, contains muscular tissue
What is an organ system?
A group of organs working together to perform a particular function
what is a catalyst?
A substance which increases the speed of a reaction without being changed or used up
what does the digestive system do
break down large food molecules into smaller ones to absorb nutrients
explain the lock and key model
enzymes have an active site with a unique shape. The substrate fits into the active site to make enzyme-substrate complex
substrate breaks down into products
what two conditions changes the rate of enzymes
Temperature and pH
what happens to activity of enzyme as temperature increases
increases rate up to a point (optimum temperature)
too high, enzymes denature and stops working
what happens to activity of enzyme as pH changes
has an optimum pH - if it becomes more acidic/alkaline, enzyme denatures
what do enzymes do?
break down big molecules into smaller ones for digestion
What enzyme converts starch and what does it convert them into?
Carbohydrase
simple sugars
give an example of carbohydrase and where it is made
amylase, salivary, glands, pancreas, small intestine
what converts proteins and what does it convert them into?
Protease
amino acids
where is protease made?
Stomach (pepsin), pancreas, small intestine
what converts lipids and what does it convert them into?
Lipase
one molecule of glycerol and three fatty acids
where is lipase made?
Pancreas, small intestine
what does small intestine and large intestine do
small
- produces the 3 enzymes
- absorbs food molecules from digestion into blood
large
- absorbs water from food
how is small intestine adapted to absorb products of digestion
- very long, 5m in humans: large SA
covered in villi to speed diffusion:
- large SA
- microvilli surround villi: even larger
- capillaries allow very good blood supply, bloodstream removes products rapidly
- thin membrane: shorter diffusion
what does the stomach do
- produces pepsin to digest proteins
- produces HCl to kill bacteria and provide optimum pH for pepsin
how and why does the body produce bile
produces in liver, stored in gall bladder, released into small intestine.
- neutralises HCl from stomach to allow enzymes in small intestine to work in less acidity
- emulsifies lipids, increasing SA to speed breakdown
Where does oxygen go when you breathe it in?
trachea - split into two bronchi - bronchioles - alveoli
how are we adapted for gas exchange
trachea - rings of cartilage to prevent collapse
breathing - brings oxygen to alveoli and takes away the co2, maintaining gradient
how are alveoli adapted for gas exchange and diffusion
- millions in lungs: huge SA
- thin walls: short diffusion path
- very good blood supply: rapidly removed to maintain gradient
What valves do?
Prevent blood flowing backwards
describe circulation in humans
double circulatory system:
deoxygenated blood pumped heart to lungs
oxygenated blood pumped lungs to heart
blood gives oxygen to organs
blood returns to heart
what does blood flow through to get to the right atria?
The vena cava
where is vena cava on diagram
LEFT side: diagram reverses
describe blood vessels that enter and leave heart
DO body - heart: vena cava
DO heart - lungs: pulmonary artery
O lungs - heart: pulmonary vein
O heart - body: aorta
explain how blood flows to the heart on the right side
- Enters right atria via vena cava
- Atria contracts, pushing blood into ventricles
- Ventricles contract, pushing blood into pulmonary artery
- valves stop backflow when ventricles contract
explain how blood flows through the heart on the left side
- Enters left atria via pulmonary vein
- Atria contract, pushing blood into left ventricle
- Ventricle contracts and leaves through the aorta
- valves stop backflow when ventricle contracts
why isnt a heart symmetrical
left has thicker muscular wall than right
left pumps blood around the entire body so needs to provide greater force, whereas right pumps only to lungs
what are coronary arteries
branch out of aorta and spread across the heart, to provide oxygen to muscle cells of heart for respiration for contraction
what is a pacemaker?
A group of cells in the right atrium that control the heart rate
what to do if pacemaker stops working correctly
artificial pacemaker - small electrical device that regulates heart rate
Features of an artery
- thick, muscular walls to withstand high pressure
- elastic fibres which stretch and recoil as blood surges
Features of a capillary
- thin walls to shorten and speed diffusion
Features of veins
- thin wall as pressure is low
- valves to stop blood flowing in wrong direction
Name the four main things in blood
Red blood cell, white blood cell, platelets and plasma
what does RBC do and what are some features
carry oxygen to organs
- contains haemoglobin, which binds with oxygen in lungs to form oxyhaemoglobin, releases oxygen when RBC travels to organs
- no nucleus to allow more room for haemoglobin
- biconcave disc to increase SA
what does WBC do and what are some features
part of immune system to fight disease
- contain a nucleus, which has DNA that encodes WBC to do its know
what does plasma do
liquid that carries
- soluble products of digestion from small intestine to organs
- co2 (aerobic respiration) from organs to lungs to be exhales
- urea from liver to kidneys to be excreted
what do platelets do
fragments of cells that help blood to clot
uses of donated blood
- replace blood lost during injury
- provides platelets for clotting
- provides proteins eg antibodies
risks of donated blood
- ensure blood type is same otherwise immune system will reject it and patient could die
- disease transmitted via blood
what is coronary heart disease?
when layers of fat build up in coronary arteries, narrowing the artery.
less blood flow = less oxygen supply to heart, can cause heart attack
What is a stent?
Tubes that inserted inside arteries that keep them open
Pros and cons of a stent
- blood can flow normally through artery
- only prevents narrowing in one region, other regions may block
- risk of blood clot near stent
what is a statin
Drugs that reduce level of bad cholesterol in blood, slowing rate of fat build up
pros and cons of statins
- reduced risk of coronary heart disease
- unwanted side effects eg liver problems
problems of poor valves
- dont fully open - heart has to pump harder, enlargens
- leaky, causing tiredness
solution to poor valves with pros and cons
mechanical valve
- lasts a lifetime
- anticlotting drugs must be taken
biological valve
- no drugs needed
- dont last long, may need replacing
what is heart faliure
when heart cannot pump enough blood around body
solution to heart failure with pros and cons
donated heart (and lungs)
- not enough donors for patients
- drugs needed to stop immune system rejecting heart
temporary artificial heart
- risk of clotting
- only temporary, not long term
risk of uncontrolled mitosis
tumours
benign vs malignant tumour
B: tumour contained in an area, a membrane, so do not invade other parts of body
M: cells can move into bloodstream & invade healthy tissue, forming secondary tumours, cancerous
causes of cancer
- uncontrolled mitosis (tumours)
- genetics eg breast
- lifestyle eg uv, smoking
- environment eg radon gas: ionising radiation - cells damaged - uncontrolled mitosis - lung cancer
how to find causes of disease
epidemiology - studying patterns of disease to determine its risk factors
causal mechanism - finding how risk factor leads to disease
how did scientists find cause of lung cancer
- scatter graph to see correlation and link between:
number of cigs per day & risk of developing lung cancer
years of smoking & risk of developing lung cancer - causal mechanism to discover that chemicals in smoke is carcogenic (damages dna - cancer)
challenge of epidemiology and how to overcome
sampling - creates bias as sample may be unrepresentative of population
large, random samples taken
risk factors of cardiovascular disease
- diet: high fat increases bad cholesterol, increasing rate of fat build-up
high salt increases blood pressure, increasing risk - smoking increases risk
- exercise decreases risk
risk factors linked to smoking
smoke is carcinogenic
- cardiovascular disease
- lung cancer
- lung disease eg emphysema
- miscarriage/premature if pregnant
risk factors linked to pregnancy
- smoking: miscarriage, prematurity
- drinking: fetal alcohol syndrome, learning difficulty
risks factors linked to alcohol
- fetal alcohol syndrome if pregnant
- liver cirrhosis and liver cancer
- addiction and memory loss
risks factors linked to type 2 diabetes
- blindness
- amputatuion
- obesity causes it
risk factors not linked to lifestyle
- environment eg radon: radioactive gas, risk of cancer
What do epidermal tissues do?
They are covered in a waxy cuticle, which helps to reduce water loss by evaporation
what does the upper epidermis do?
It’s transparent, so that light can pass through it to the palisade layer
what does lower epidermis do
covered in stomata
- allow co2 to enter, oxygen to leave
- regulates water leaving/entering
surrounded by guard cells
- swell in high light intensity, stomata opens
- closes stomate in hot conditions to reduce water loss via transpiration
what does the palisade mesophyll layer do?
lots of chloroplasts - chlorophyll get lots of sunlight
what does spongy mesophyll do
full of air spaces
- allow co2 to diffuse from stomata to palisade cells
- allow oxygen to diffuse from palisade cells to stomata
what does the xylem do
- transports water up plant (roots to stem and leaves) for photosynthesis
- transports dissolved mineral ions eg magnesium for chlorophyll
what does the phloem do
translocation: transports sugars from photosynthesis from leaves to rest of plant, for respiration or store as starch
what does the meristem do
at shoots and roots, contains stem cells which can become any cell
describe transpiration stream
evaporation from leaf surfaces
- evap occurs from cells within leaf
- vapour diffuses through spongy mesophyll
- exits via stomata
- xylem replaces water lost and absorbs more from root hair cells
importance of transpiration
- water for photosynthesis
- mineral ions eg magnesium for making chlorophyll
- cools leaf in warm weather
what affects rate of transpiration
- temp: hotter = faster evaporation
- humidity: dry = faster evaporation
- wind: wind removes vapour = more vapour can evaporate
- light intensity: brighter = faster photosynthesis
