O slideshow foi denunciado.
Seu SlideShare está sendo baixado. ×

Control and Coordination Part 2.pdf

Anúncio
Anúncio
Anúncio
Anúncio
Anúncio
Anúncio
Anúncio
Anúncio
Anúncio
Anúncio
Anúncio
Anúncio
Próximos SlideShares
Chapter 14- Homeostasis.pdf
Chapter 14- Homeostasis.pdf
Carregando em…3
×

Confira estes a seguir

1 de 39 Anúncio
Anúncio

Mais Conteúdo rRelacionado

Mais recentes (20)

Anúncio

Control and Coordination Part 2.pdf

  1. 1. Muscle Contraction • Contraction of striated muscles; only contract when stimulated by impulses that arrive (neurogenic) • Different with cardiac and smooth muscles • *refer to Table 15.2 Pg.407
  2. 2. The Structure of Striated Muscles • One bicep contains of thousands of mucle fibres. • Highly specialised cell with organised contractile proteins in the cytoplasm forming a multinucleate muscle fibre • Sarcolemma- Cell surface membrane • Sarcoplasm- Cytoplasm • Sarcoplasmic Reticulum (SR)- Endoplasmic reticulum
  3. 3. • Deep infoldings in the sarcolemma forming the transverse system tubules (T-tubule) • Membranes of SR have high number of protein pumps; transport calcium ions ino the lumen (cisternae) of SR • High number of mitochondria; packed tightly between myofibrils  aerobic respiration to generate ATPs
  4. 4. • Striations on muscle fibre- Myofibrils -striped in same way and lined up -made up of thick and thin filaments • Thick filaments are made up of myosin • Thin filaments are made mostly of actin
  5. 5. Structure of a Muscle
  6. 6. Structure of Muscle Fibre
  7. 7. • I band = only thin filaments (lighter part) • A band = overlap of thick and thin filaments (darkest part) • H band = only thick filament present • Z line= attachments of actin filaments • M line = attachments of myosin filaments • Sarcomere = part between Z line -z-line shaped as Z-disc as the myofibrils are packed into cylindrical shape.
  8. 8. The Structure of Thick and Thin Filaments • Thick filaments; made up of myosin (fibrous protein with globular head) -lie together in in bundle (M-line) -globular heads are pointing away from M-line • Thin filaments; made up of actin (globular protein) -chain of actin molecules are twisted, forming the filament -tropomyosin twisted together with actin -troponin attached to the actin at intervals
  9. 9. Structure of one sarcomere
  10. 10. Muscle Contraction • Sliding filament model; the movement of muscle -movement generated by contraction -the sarcomere in each myofibril get shorter as the Z discs get pulled closer • Energy for the movement coming from ATPs attached to the myosin heads *each myosin head is ATPase
  11. 11. When muscle contracting.. 1. Calcium ions are released from SR, get bind to troponin; troponin gets to change the shape. 2. Troponin and tropomyosin move to different position on the thin filaments; -exposing the actin-binding site to myosin -forming cross-bridges between thin and thick filaments
  12. 12. 3. Myosin heads move; pulling the actin filaments to the centre of sarcomere (H band become shorter) 4. Myosin head hdyrolyse the ATP, provide energy for the head to release the actin -the heads move back to the previous position and bind again to the exposed site of actin 5. Thin filaments moves due the previous stroke -myosin head bind to actin further, closer to the Z- disc
  13. 13. • The myosin head moves again, pulling the actin filaments even further; hydrolyse more ATPs to repeat the process • Can continue as long as the troponin and tropomyosin active sites are not blocked, and the ATPs are supplied
  14. 14. Control and Coordination in Plants
  15. 15. Control and Coordination in Plants • Responds to the factors like gravity, light and water availability, in changing the growth • The responses are done by quick changes in turgidity, such stomata respond to changes in changes in humidity, carbon dioxide concentration and water availability.
  16. 16. Electrical Communication in Plants • Plant action potentials are triggered when membrane is depolarised (have the same way of electrochemical gradient as animal cells) • Some species, they have the response to the stimuli coordinated by action potentials. -Mimosa, respons to the tocuh by folding its leaves
  17. 17. • Depolarisation of plants; results from the outflow of negatively charged chloride ions Cl- (not from the inlfux of positively charged Na+ • Repolarisation achieved in the same way by the outflow of potassium ions, K+ • Plants do not have nerve cells but transmit the electrical waves activity, same as along the neurones in animals. • Action potentials are trasmitted along the the cell membrane of plant cells, from cell to cell through plasmodesmata
  18. 18. • The action potentials generated last much longer and travel slower than in animal neurones. • Different stimuli can trigger the action potentials of the plants. -e.g dripping acid solution on soya bean plant -Colorado beetle larvae feeding on potato leaves • these action potentias are to coordinated stress signals and damage signals.
  19. 19. Venus Fly Trap • Dionaea muscipula; carnivorous plant that obtain nitrogen supply from small animals (insects) • Special structure of leaf divided into 2 lobes; -red coloured inside of the lobe and secrete nectar to attracts insects • Each lobes has 3 stiff sensory hair (respond if deflected)
  20. 20. • Outer edge of the lobes have stiff hair (thorn- like) interlock to trap the insects when closed. • The lobes surface have many gland that secrete enzymes for the digestion. touch stimuli on the sensory hair will stimulate the action potential, causing the lobes to fold and capture the insect
  21. 21. • Deflection of sensory hair activates the calcium ion channels (at the base of the hair) -the channels open, and influx of calcium will trigger the receptor potential. • If 2 of 3 hairs stimulated; or one hair is stimulated twice within 20 – 35 sec., action potentials wil travel across the trap. • If second stimulus trigger outside from the intervals (first stimulus), it will start as first again. • Time between stimulus and response is 0.5s -less than 0.3s taken to close and trap the insect
  22. 22. • To completely closed the trap, the leaf need ongoing trigger of the hair (struggle movement of the insects) • Further stimulation of inner lobes will cause influx of calcium ions into gland cells. -exocytosis of enzyme-containing vesicles (same way as synapse action) • The leaf will be closed up to a week to complete the digestion. -cells of the upper surface of midrib grow slowly and will reopen
  23. 23. • Adaptations of Venus fly trap: 1. One stimulus on single hair will not trigger the closure. 2. The gaps between the stiff hairs, allow very small insects to escape -prevent waste energy of digesting small insects
  24. 24. Chemical Communications in Plants
  25. 25. Plant Growth Regulators • Plant hormones are used to communicate within the plantss. • The hormones are released by a variety of plant tissues (not by special glands by animals) • They moves in plants by cell to cell (active transport or diffusion); or transported through phloem/xylem sap
  26. 26. Auxins • Influent on growth aspects (including elongation growth) which determines the overall length of roots and shoots. • IAA (indole 3-acetic acid) the principal chemicals of auxin
  27. 27. • IAA is synthesised in the growing tips (meristems) of shoots and roots -transported back down the the shoot or up the root by active transport from cell to cell, or lesser extent in phloem sap • Auxins stimulate cells to pump H+ ions (protons) into the cell wall. -become acidified, leads to loosening the bonds between cellulose microfibrils and the matrix surrounding them. -The cell wall absorps water (osmosis); increase in internal pressure cause the the walls to stretch and the cells will elongate.
  28. 28. 1. Molecules of auxins bind to the receptor protein (on cell surface membrane) 2. Stimulates ATPase proton pumps to move H+ ions from cytoplasm into the cell walls. 3. Protein (expansin) activated by the lowering of pH -loosening the bond between cellulose microfibrils 4. Microfibrils move past each other, allowing the cell to expand (with only little strength loss of the cell wall)
  29. 29. Gibberellins • Plant growth regulators synthesised in most parts of the plants. • High conc. in young leaves and seeds for the growth process. • Promotes different cell extension different with auxins -gibberellins stimulates the XET enzymes (in the cell wall of stems) -XET breaks the bond within the hemicellulose molecules; cellulose microfibrils can moves apart allowing for the extension.
  30. 30. • Gibberellins are involved in the controls of germination of cereal seeds (wheat, barley) • The seed is in dormant state when shed from the parent plant: allows to survive the adverse conditions (e.g only germinating when the temperature rise) • The seed contain embryo; which will grow to form the new plant when germination occur -embry is surrounded by endosperm; energy storage of polysaccharide starch -outer edge of endospermis aleurone, protein-rich layer -the seed itself is covered by tough, waterproof protective layer
  31. 31. 1. Water uptakes initiates the germination 2. Embryo synthesise gibberellins 3. Aleurone layer synthesises amylase in respond to gibberellins 4. amylase hydrolyses starch to maltose 5. Maltose is broken down to glucose and tansferred to the embryo for respiration

×