Biology: cell organisation
- Created by: Anisa.Khan
- Created on: 12-04-18 18:35
cell organisation: Tissues, Organs and Systems
- In most organisms, cells arranged into tissues
- tissue is a group of cells with similar structure and function which all work together to do a job e.g: muscular tissue contracts to produce movement glandular tissue produces substances such as enzymes and hormones epithelial tissue covers organs
- organs are groups of different tissues, all work together to perform a similiar job
- each organ may contain several tissues
- For example: the stomach is an organ that contains: muscle tissue, contracts and churns contents glandular tissues to produce digestive juices epithelial tissue to cover the outside and inside of the stomach
- organs organised into organ systems, which are groups of organs working together to do a particular job
- the digestive system is an example of an organ system, several organs work together to digest and absorb food
- lots of organ systems work together to make an organism
cell organisation: specialised cells
specialised cells
- cells are the basic building blocks of life
- as an organism developes, cells differentiate to form different types of cells, become specialised
- most types of animal cell diffrentiate at the early stages but plant cells differentiate throughout their life
- as a cell diffrentiates: it may change shape different sub cellular structures develope to let it to carry specific function
- specialised animal cells include:
- sperm
- nerve and muscle cells
- in plants: root hair, xylem and ploem cells
cell organisation: Digestion - Enzymes
Enzymes
- enzymes are biological catalysts, speeding reactions in all living organisms
- enzymes have a number of properties: all large proteins space within protein molecule - actice site each enzyme cataylists a specific reaction works best at a specific temperature
- the lock and key theory - explains how enzymes work, chemical that reacts call sustrate, fits into enzymes active site (lock)
- high temp and extremes of ph make enzymes change shape - denaturing
- enzyme cannot work work once it has been denatured becuase substance cannot fit into active site- lock and key can no longer fit together
cell organisation: Digestion - Enzymes in digestiv
- digestive enzymes are produced by specialised cells in glands and in lining of the gut:
1. the enzymes pass out of the cells into the digestive system 2. come into contact with food molecules 3. they catalyse the breakdown of large insoluble molecules into smaller soluble molecules
- the digestive enzymes, protease, lipase and carbohydrase, digestproteins, lipids and carbohydrates to produce smaller molecules that can be easily absorbed into the bloodestream
- amylase produced in the salivary glands and the pancreas carbohydrase breaks down starch into sugar
- protease: produced in the stomach, pancreas and small intestine breaks down proteins and amino acid
- lipase: Produced in pancreas and small intestine breaks down lipids into fatty acids and glycerol
cell organisation: Bile and Digestion
- bile is a liquid made in liver and stored in he gall baldder
- alkaline to neutralise hydrochloric acid from the stomach
- it also emulsfies fat to form small droplets, increasing the surface area for enzymes to act on
- the alkaline conditions and large surface area inreacese the rate at which fat is broken by lipase
cell organisation: Blood
- blood is a tissue
- made of liquid called plasma, three different components suspended in it: red blood cells white blood cells platelets
- plasma transports various chemical substances around body like products of digestion, hormones antibodies, urea and carbon dioxide
- red blood cells: contain haemoglobin binds to oxygen transport it from lungs to tissues and cells, needs for respiration
- do not contain nucleus there is more room for haemoglobin
- very small, fit through tiny capillaries, large surface area that oxgen can quickly diffuse across
- white blood cells: help protect body against infection can change shape, squeeze out of blood vessels into tissues or engulf organisms
- platelets fragment of cells, collect at wounds, trigger blood clotting
cell organisation:blood vessel
- Blood passes around body in blood vessels
- Body contains three different types of blood vessel
- Arteries: take blood from heart to organs thick walls made from muscles and elastic fibres
- Veins: take blood from your organs to heart thin walls and valves prevent backflow
- Capillaries: allow substances needed by cells to pass out blood allow substances produced by cell pass into blood narrow thin walled blood vessels
cell organisation: The Heart
- Heart pumps blood around body in double circulatory system
- blood passes through heart twice on each circuit
- Four chambers in heart: left and right atria, recieve blood from veins left and right ventricles, pump blood our of arteries
- Blood enters heart through atria
- Atria contracts and forces blood into ventricals
- Ventricals contract force blood out heart
- Valves make blood flow correct direction
- Natural resting heart rate contolled by group cells located in right atrium, act as pacemaker
- Artificial pacemakers electrical devices used to correct irregularities in heart rate
cell organisation: Gaseous exchange
- heart send blood to lungs via pulmonary atery
- air obtained by breathing reaches the lungs through trachea, has rings of cartilage to prevent collapsing
- trachea divides into two tubes- the bronchi
- bronchi divides to form bronchioles
- bronchioles divide until end in tiny air sacs - alveoli
- millions of alveoli, adapted to be efficient at exchanging oxygen and carbon dioxide: have large moist surface area have rich blood supply close to blood capillaries, distance for gases to diffuse - small
- blood taken back to heart through pulmonary vein
cell organisation: Health and disease
- good health - state of physical and mental wellbeing
- disease causes by part of body not working properly, can affect physical and or mental health
- diseses can be divided into 2 main types: communicable diseases and non- communicable diseases
- non communicable diseases cannot be spread between organisms, communicable can
- example of how diseases can interact with each other: viruses infecting cells can be the trigger for cancers , cervical cancers disease of immune system mean that individual more likely to catch infectious disease immune reactions triggered by pathogen can cause allergies: skin rashes and asthma
- non communicable disease: diabetes, can change persons life and cost countries large sums of money
cell organisation: Risk factors in diseases
- non communicable diseases often caused by interaction of number factors
- factors called risk factors, make more likely person going to get disease
- risk factors: aspects persons lifestyle substances in persons body or enviroment
- sometimes clear risk factor and chance of getting disease
- this does not mean that risk factor causes disease
cardiovascular disease =lack of excersise/smoking Type 2 diabities =obesity Liver and brain damage =excessive alcohol intake Lung disease, lung cancer =smoking Skin cancer= ionising radiation Low birth weight in babies = smoking during pregnancy Brain damage in babies =excessive alcohol intake during pregancy
cell organisation: Diseases of the heart
- coronary heart disease- layers of fatty material build up inside coronary ateries and narrow them
- Treatments for coronary heart disease include: stents to keep coronary arteries open statins to reduce blood cholesterol levels and slow down the rate at which fatty materials build up
- heart valves may become faulty, developing leak pr preventing valve opening properly
- faulty valves can be replaced using biological or mechanical valves
- for cases of heart failure: donor heart or heart and lungs - transplanted artifiicial hearts - used to keep patients alive while waiting for heart transplant to to allow heart recover
cell organisation: Cancer
- cancer - non communicable disease
- genetic risk factors for some cancers may run in families
- cancer- caused by uncontrolled cell division - form masses of cell = tumours
- 2 main types of tumours: Benign tumours = do not spread around body Malignant tumours spread = blood to different parts of body, form secondary tumours
cell organisation: transport in plants
Plant tissues
- epidermis = covers other surfaces of plant for protection
- palisade mesophyll = main site of photosynthesis in the leaf
- spongy mesophyll = air spaces betwwen cells allow gases to diffuse through leaf
- xylem vessels =Transport water and minerals through plant , from roots to leaves, supports plant
- phloem vessels = transports dissolved food materials through plant
- meristem tissue = found mainly at tips of roots and shoots, where produces new cells for growth
- plant tissues gathered together to form organs
- leaf is plant organ
- structures of tissues in leaf related to functions
cell organisation: water transport
- water enters plant from soil- through root hair cells by osmosis
- root hair, xylem and phloem cells specialisd to transport water, minerals and sugars around plant
- water contains dissolved minerals
- water and mineral transported up xylem vessels from roots to stems and leaves
- at leaves, most water evaporates + diffuses out of stomata
- loss of water from leave = transpiration
- helps draw water up xylem vessels from roots
- many factors affect rate of transpiration: increase in temp - increase rate, more energy transfered to water allow evaporate faster air flow- increase rate, blow away water vapour alowing to evaporate increased light intensity - increase rate , cause stomata to open increase - humidity decrease rate, air contains more water vapour
- in leaf, role of guard cell =to open and close stomata
- at night stomata close - carbon dioxide not needed - photosynthesis, closing stomata reduces water loss
- when water plentiful - guard cells take water+bend , causes stomata to open, gases for photosynthesis free to move in and out stomata along with water
- when water scarce-loosing water, stomata change shape and close
cell organisation: Translocation
- phloem tissues transports dissolves sugars from leaves to rest of plant
- movement of food through ploem tissues called translocation
- phloem cells adapted for this function
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