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S3 Biology, Excretion, Egestion(diff from excretion), download HEAD,…

- - - - Higher conc to lower conc
        
        Down a conc. gradient
    - - Surface area to volume ratio
      - Diffusion distance
      - Concentration gradient
    - - When there is dynamic equilibrium (same conc.)
    - - examples
        
        in humans
        
        lungs(alveoli)
        
        site of gaseous exchange
        
        small intestine
        
        absorb nutrients
        
        in plants
        
        leaves(stomata)
        
        respiration
        
        roots
        
        nutrients
      - adaptations
        
        small intestine
        
        long, coiled and folded
        
        inner walls of SI are folded
        
        finger-like projections(villi)
        
        epithelial tissue of SI
        
        finger-like folding of CSM(microvilli)
    - - diff in conc. gradient
    - - hypertonic(more concentrated)
      - hypotonic( more diluted)
      - isotonic(same concentration)
  - - - Partially permeable membranes
      - Only for water
      - Moves from high water potential to low water potential
        
        What is water potential?
        
        Potential energy of water molecules per unit vol.
        Max WP=0. Anything <0 is impure.
    - - To maintain homeostasis
      - Examples
        
        Kidneys, Small intestine, blood capillaries
      - PLANTS
        
        In lower water potential
        
        Cells becomes plasmolysed and flacid
        
        The spaces created are filled with the concentrated solution.
        
        cell wall is fully permeable
        
        In higher water potential
        
        Cell expands- becomes turgid
        
        Note
        
        Cell does not burst because of cell wall
        
        Cells always have turgor pressure to allow plant to stay upright
      - ANIMALS
        
        In higher water potential
        
        Expands, becomes turgid and bursts eventually
        
        In lower water potential
        
        Undergoes crenation, cell has crenated
    - - Diff in water potential gradient
      - Temperature
        
        Particles have more KE, move in/out of membrane faster.
  - - - energy
      - partially permeable membrane
    - - against conc. gradient
      - lower conc. to higher conc.
    - - more mitochondria
        
        release more energy
    - - in humans
        
        epithelial cells
        
        leftover glucose diffuses to epithelial cells for respiration
      - in plants
        
        RHC
        
        nutrients diffuses via A.T.
        
        maintain low w.p.
        
        ensure constant entry of water
    - - helps organisms to take in essential substances even if they are at a lower conc.
- - - - cell surface membrane
        
        controls/ regulates entry/exit of substances
    - - cytoplasm
        
        site of chemical rxn
        
        eg anaerobic respiration
      - nucleus
        
        contains genetic info
        
        controls cell activity
      - rough endoplasmic reticulum (RER)
        
        transports the proteins produced
        
        ribosomes attached on RER
      - smooth endoplasmic reticulum (SER)
        
        lipid synthesis/production
        
        detoxification: breakdown harmful substances eg drugs, alcohol
      - ribosomes
        
        produce proteins
      - golgi apparatus
        
        modification and repackaging of proteins
      - mitochondrion(single)/Mitochondria(plural)
        
        site of aerobic respiration
      - cell wall
        
        protects cell from injury
        
        gives the plant cell a fixed shape
        
        does not burst or crenated; becomes plasmolysed or turgid
      - chloroplast
        
        contain green pigment called chlorophyll which is essential for photo synthesis/absorb light
      - vacuole
        
        plants: large; contains cell sap, sugar, mineral salts and a.a (single)
        
        animal: smail, contain water and food substances exist temporarily (multiple)
      - chromatin
        
        proteins and DNA
        
        gentic material
      - comparision
  - - - -Ribosomes on RER produces proteins which diffuses into the RER.
        -Transport vesicles contain polypeptide buds off the surface of RER to transport the polypeptide to the GA where the vesicle fuse to release the polypeptide.
        -The GA chemically modifies and repackages the polypeptide into functional proteins.
        -Secretary vesicles transport the protein to and fuses with the cell surface membrane to realise the protein out of the cell.
    - - Reduces the workload of a cell
        
        Cell becomes more efficient
      - Achieved via differentiation (Another Process)
        
        Lose/ Develop structures to carry out specific functions
        
        Specialised cells
        
        Animal Cells
        
        Red Blood Cell
        
        Biconcave Shape
        
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        Lose nucleus and other organelles
        
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        Flexible
        
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        Muscle Cell
        
        Plant Cells
        
        Root Hair cells
        
        Long narrow protrusion
        
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        Concentrated Cell Sap
        
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        A lot of mitochondria
        
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        Xylem Cell
        
        Lignified Walls
        
        Hollow Continuous Tube
        
        Cells are Dead
      - If cell is unable to carry out its function
        
        Other functions can still be carried out.
- - - - characteristics
        
        catalyst: remain chemically unchanged at the end of the rxn and increase rate of rxn
        
        Proteins folded into a 3D shape
        
        substrate specific
        
        affected by ph
        
        affected by temperature
        
        denaturation: enzyme loses specific 3D shape-unfolds itself-break H2 bonds
        
        Irreversible
    - - lower activation energy
        
        the energy required to start the rxn
        
        cannot have high temp to increase rate of rxn as cells will die.thus enzymes are needed
        
        lowers it by creating an alternate pathway
        
        Amount of products is still the same
    - - substrate is the key-enzyme is the lock
      - substrate site is complementary to substrate
        
        substrate complete in production formation
- - - - Plasma
      - Red Blood Cells
    - - White Blood Cells (aka Luekocytes)
        
        lymphocytes
        
        Rupture bacterial surface by latching onto it
        
        clumps bacteria so easily ingestable
        
        Attach to virus -> prevent binding of host cell
        
        characteristics
        
        Round in shape
        
        Large, little granular Cytoplasm
        
        Circular Nucleus
        
        Phagocytes
        
        Phagocytosis
        
        Engulf
        
        Ingest
        
        Digest
        
        characteristics
        
        Lobed nucleus
        
        small, very Granular cytoplasm
        
        large conc. of vesicles
        
        Shape: Irregular
        
        Structure: (see phago and lymphovytes nucleus char)
      - Platelets aka thrombocytes
        
        characteristics
        
        membrane-bound cell fragments of cytoplasm of bone marrow cells
        
        helps in blood clotting to prevent excessive blood loss and entry of microbes
        
        Damaged blood vessel adn platelets release THROMBOKINASE
        
        (inactive) PROTHROMBINE ------ thrombokinase and ca2+ ------> THROIMBINE (active)
        
        Fibrinogen (soluble) ------ thrombine (catalase conversion) ----> insoluble fibrin threads
        
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  - - - Arteries
        
        Structure
        
        has thick muscular walls to withstand high blood pressure
        
        small lumen compared to walls
        
        no valves
        
        Function
        
        carries oxygenated blood away from the heart (except for pulmonary artery, which transports deoxygenated blood away from heart to the lungs)
        
        Adaptations
        
        has a high blood pressure
        
        controls amount of blood that flows through
        
        blood flows in fast spurts
      - Capillaries
        
        Function
        
        Transports blood to and from all parts of the bodies, distributing oxygen, water and nutrients, as well as collecting metabolic waste products
        
        Structures
        
        walls are one cell thick to decrease diffusion distance and increase rate of diffusion
        
        walls are partially permeable for transfer of substances via diffusion, osmosis, and active transport
        
        Adaptations
        
        branches repeatedly to increase SA to increase rate of exchange of substances
        
        low blood pressure, slow blood flow to increase time for diffusion to occur
        
        transports both oxygenated and deoxygenated blood
      - Veins
        
        Structure
        
        thin muscular walls
        
        does not need to withstand high pressures
        
        larger lumen compared to walls
        
        has semilunar valves
        
        to stop backflow of blood
        
        Function
        
        carries deoxygenated blood back to the heart (except for pulmonary vein, which carries oxygenated blood from lungs to heart)
        
        Adaptations
        
        smooth, slow flow of blood
        
        has lower blood pressure
        
        surrounding tissues squeeze to help push blood up
    - - What is it?
        
        formed by forcing plasma without proteins out of the blood capillaries
        
        diluted plasma that has white blood cells but no red blood cells or plasma proteins
      - Function
        
        food and oxygen diffuse out of capillaries, into tissue fluid, and into cells
        
        waste materials and carbon dioxide diffuse out of cells, into tissue fluid, through capillary walls and into the blood, which transports the excretory products away for removal
      - How it works:
        
        Osmotic pressure
        
        arteriole end of capillary has high blood pressure, and venule end of capillary has low blood pressure. arteriole pressure is higher than the osmotic pressure between the 2 ends, while venule pressure is lower than the osmotic pressure
- - - - Bacteria
        
        Glucose-->CO2+ethanol+small amounts of energy
        
        occurs when there is no O2
      - Humans
        
        Glucose-->Lactic acid+small amount of energy
        
        occurs in cytoplasm
        
        occurs only when insufficient O2
    - - O2+Glucose-->CO2+H2O+Large amounts of energy
      - occurs in mitochondria
      - factors affecting
        
        Temp
        
        Amount of mitochondria
        
        pH
        
        Availability of O2
        
        Availability of glucose
        
        Demand of O2
  - - - emphysema
        
        violent coughing breaks partition walls between alveoli
        
        Reduces SA of alveoli
        
        lungs become inflated and loses elasticity
        
        Results in wheezing;severe breathelessness
      - bronchitis
        
        Epithelium lining of bronchi becomes inflamed
        
        epithelium secretes excess mucus
        
        cilia is paralysed due to tar
        
        cannot sweep mucus to pharnyx
        
        Airway blocked
        
        cough persistently
        
        Increases frequency and chances of airway infection
      - Carbon Monoxide
        
        combines with haemoglobin irreversibly
        
        less haemoglobin to carry O2
        
        Fatigue
        
        Retarding of fetus development
      - Nicotine
        
        causes addiction
        
        triggers release of dopamine
        
        causes blood clot and atherosclerosis
        
        blood pressure increases
- - - - Kidney
        
        Functions
        
        Osmoregulation
        
        Controls water and solute levels in blood to maintain constant water potential in body
        
        Stimulus:decrease in blood water potential
        
        Receptor:Hypothalamus
        
        Corrective mechanism:Hypothalamus secretes more Antidiuretic Hormones(ADH) which causes the cells of the wall of the collecting duct to be more permeable. Hence, more water is reabsorbed into the bloodstream
        
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        Produces urine
        
        Ultrafiltration
        
        High hydrostatic pressure generated by larger diameter of afferent arteriole and smaller diameter of efferent
        
        Small particles(filtered):
        Glucose, amino acid, water molecules, salts
        
        Large particles(unfiltered):
        Protein, RBCs, WBCs, fats, platelets, plasma proteins
        
        Selective reabsorption
        
        All amino acids and glucose are absorbed back into bloodstream
        
        Some water is absorbed into bloodstream
        
        Structures
        
        Medula
        
        Cortex
        
        Renal artery/vein
        
        Ureter
        
        Renal pelvis
        
        Pyramids
        
        Fibrous capsule
        
        Nephron
        
        In medulla
        
        Collecting duct
        
        In cortex
        
        Glomerulus
        
        Distal Convoluted tubule
        
        Bowman's Capsule
        
        Proximal Convoluted Tubule
        
        Kidney failure
        
        Unable to carry out ultrafiltration and selective reabsorption
        
        Accumulation of too much urea= toxic levels
        
        Solved using a dialysis machine
        
        Blood is drawn from artery and then filtered and returned via vein in the arm
        
        blood flows through a very long tubing in dialysis machine
        
        membrane of tubing is partially permeable and bathed in dialysis fluid
        
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      - Urinary bladder
      - Ureter
      - Urethra
      - Dorsal aorta
      - Renal artery and vein
- - - - Right Ventricle
        
        Pulmonary Artery
        
        LUNGS
        
        Pulmonary Vein
        
        Left Atrium
      - Left Ventricle
      - Coronary vein