Biology [Module 5:Muscle&Animal&Plant hormones]

hormones

-molecules that are secreted by endocrine glands

-chemical messengers carrying signals to specific target tissues

peptide hormones

—adrenaline,insulin,ADH,glucagon

-proteins that are non lipid soluble

-so cannot diffuse across the phospholipid bilayer

-so they would bind to complementary receptors on the plasma membrane of the target cell and they release a second messenger (cAmp) in cells

-cAMP activates enzymes to initiate a response

how is cAMP made

-adrenaline binds to a complementary receptor on plasma membrane

-this activates the G protein

-G protein activates the enzyme Adenyl cyclase

-Adenyl cyclase catalyses the conversion of ATP into cAMP

steroid hormones

-oestrogen and testosterone

-lipid soluble so can diffuse across the phospholipid bilayer by simple diffusion

-in cytoplasm they would bind to complementary receptors on target cell to form steroid hormone receptor complex

-SHRC diffuses into nucleus and binds to DNA to initiate transcription

pancreas (endocrine gland)

-ductless

-produce an secrete hormones directly into the blood

pancreas (exocrine gland)

-ducts

-produces and secrets digestive enzymes

pancreas structure

increase in blood glucose

-detected by beta cells of the islet of langerhans

-secrete insulin into blood

-insulin detected by receptors on liver and muscle cells

-liver and muscle cells remove glucose from blood and convert it into glycogen

decrease in blood glucose

-detected by alpha cells in islet of langerhans

-secrete glucagon into blood

-glucagon binds to receptor on liver cells

-liver cells convert glycogen into glucose and release glucose into blood (glycogenolysis)

regulation of insulin secretion

-K+ channels open K+ ions diffuse out the beta cell

-when blood glucose conc is high glucose diffused into beta cell and is respired to produce ATP

-ATP blood K+ channels protein depolarising the mem(+) as k+ ions accumulate in the beta cell

-the depolarisation causes the ca2+ channels to open so ca2+ ions diffuse in

-signaling for vesicles containing insulin to fuse with the plasma membrane secreting insulin into the blood

symptoms of diabetes

-weight loss

-tiredness

-extreme thirst

-high blood glucose

if not managed:

-kidney failure

-blindness

-amputation

type 1

-insulin dependent

cause type 1

-auto immune response destroys beta cells

-antigen on beta cells are recognised as foreign so antibodies are produced to destroy them

treatment type 1

-insulin injection

-immunotherapy drugs

-reprogramming the immune system to stop attacking beta cells of the pancreas

type 2

-non insulin dependent

cause type 2

-receptors are no longer responsive to insulin

factors type 2

-obesity

-high sugar diet

-family history

treatment type 2

-less sugar diet

-medication

-low calorie soups

insulin treatment for type 1

-GM insulin

-less risk of rejection compared to pigs

-cheaper to produce

-stem cells

-can be used to produce new beta cells

auxins

-promotes cells elongation

-inhibitor lead abscission(leaf fall)

-inhibits growth of side shots

—uses:rooting powder

gibberelins

-promote seed germination and elongation of stems

—uses:sugar cane production

abscissic acid

-inhibits seed germination and growth ,stress hormone

-causes stomatal closure when the plant is stressed by low water

—uses:possibly seed bank

cytokinins

-promotes cell division

-prevents aging (senescence)

—uses cell tissue culture

ethene(gas)

-promotes fruit ripening/absiscion

-speed up fruit ripening

seed germination

-seed absorbs water

-embryo activated

-produces gibberellin

-which stimulates digestive enzymes to be activated that will break down energy storage molecules (starch,oil) which is respired to produce ATP

synergistic

work together

antagonistic

oppose one another

tropisms response

-growth response in a given direction

-towards the stimulus=positive

-away=negative

nastic response

non growth response to a stimulus in a given direction

how auxin causes positive phototropism

-auxin is produced at the tip of the shoot (apical meristem ) causing apical dominance

-root tip detected by the sunlight

-auxin moves to the shaded area=uneven distribution of auxin

-cells in the shaded area elongate more so bend towards the sunlight

effect of auxin on cell elongation in root tip

-cells in root to produce auxin

-they detect gravity

-uneven distribution of auxin with more auxin in the lower region of the roots

-where auxin inhibits cell elongation with the roots bending and growing downwards

skeletal muscles

• tubular shape

• striated

• multinuclated

• voluntary movemonts eg,
  walking; movement of skeleton.

cardiac muscles

-tubular and branched

-striated

-one nucleus

-contracts to pump blood

smooth muscle

-spindle shape

-non striated

- one nucleus

-involuntary movement

-vasodilation of smooth muscle in arteries and veins

structure of skeletal muscle

-under the light microscope are seen as a bundle of muscle fibres (muscle cells)

structure of actin and myosin

similarities between cellulose vs skeletal

-hydrogen bonds

-bundles of fibres

-repeating units(beta glucose in cellulose,sacromere is skeletal muscle)

differences between cellulose vs skeletal muscle

sliding filament theory of muscle contraction

neuromuscular junction