Characteristics of sliding filament model
Z lines get closer
Sarcomeres shortens
I band narrows
H zone narrows
Key Terms
Characteristics of sliding filament model
Z lines get closer
Sarcomeres shortens
I band narrows
H zone narrows
What does simultaneous contraction of several sarcomeres allow
Myofibrils and then muscle fibres to contract —-> enough to pull a bone
Neuromuscular junction
Action potential arriving at axon of motor neurone opens VG Ca2+ to flood into tip
Vesicles of acetylcholine to move towards membrane & f...
Cross bridge muscle contraction cycle
Tropomyosin is blocking myosin binding site in actin
Ca2+ binds to troponin causing a conformational change, tropomyosin moves
Myosin h...
Where does SR get Ca^2+
Active absorption from sarcoplasm
Supply of ATP for muscular contraction
Aerobic respiration - oxidative phosphorylation
Anaerobic respiration - glycolysis
Glycogen —> glucose
Creatine phosphate can ...
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| Term | Definition |
|---|---|
Characteristics of sliding filament model | Z lines get closer Sarcomeres shortens I band narrows H zone narrows |
What does simultaneous contraction of several sarcomeres allow | Myofibrils and then muscle fibres to contract —-> enough to pull a bone |
Neuromuscular junction | Action potential arriving at axon of motor neurone opens VG Ca2+ to flood into tip Vesicles of acetylcholine to move towards membrane & fuse Acetylcholine diffuses across synapse and binds to receptors on sarcolemma Na+ channels open and wave of depolarisation passes down transverse tubules Passes to SR which releases Ca2+ into the sarcoplasm |
Cross bridge muscle contraction cycle | Tropomyosin is blocking myosin binding site in actin Ca2+ binds to troponin causing a conformational change, tropomyosin moves Myosin heads bind to actin, forming cross bridges between filaments Myosin heads move, pulling the actin filament. ADP and Pi are released during the power strike A new ATP molecule attaches to myosin head, breaking cross bridge ATP hydrolyses and myosin head returns to its orig. position |
Where does SR get Ca^2+ | Active absorption from sarcoplasm |
Supply of ATP for muscular contraction | Aerobic respiration - oxidative phosphorylation Anaerobic respiration - glycolysis Glycogen —> glucose Creatine phosphate can combine w/ ADP to form ATP |
Where is creatine phosphate found | Sarcoplasm |
Supply of energy of slow twitch muscle | Aerobic respiration |
Supply of energy for fast twitch muscle | Anaerobic respiration |
Where is the cardiovascular centre | Medulla oblongata - this alters the excitation wave frequency |
Frequency of heart excitation | 60-80 bpm |
What is the heart rate regulated by | SAN | Nerves connect cardiovascular centre to the SAN |
Nerves involved in controlling heart rate | Accelerans | Vagus |
Accelerans | Causes release of noradrenaline at SAN Increases HR (sympathetic) |
Vagus nerves | Causes release of acetylcholine at SAN, reduces HR (parasympathetic) |
Sensory inputs that increase HR | Increased muscle movement (muscle stretch receptors) Decrease in pH (chemoreceptors) Adrenaline in blood |
Sensory inputs that decrease HR | Increase in bp (stretch receptors - carotid sinus) | Decrease in dissolved CO2 (chemoreceptors) |
Why do plants kept in the dark grow taller than those in the light | Auxin is more present in the dark |
Plant growth substances vs animal hormones | Hormones travel faster in animals Synthesised in endocrine glands vs cells sites Slow acting in plants vs fast acting in animals |
Why is temp controlled in investigations on effect of plant hormones | So temp does not affect results as temp affects enzyme activity |
Why are monkeys used for human research | Closely related Both primates Similar physiology |
Actions of parasympathetic nervous system | Increases blood flow to digestive system, allows peristalsis Decreases HR Decreases airway diameter Sexual arousal Constricts pupils |
Why is glycogen found in striated muscle | Glycogenolysis Glucose can undergo glycolysis to produce ATP Energy storage |
Uses of mitochondria in muscular contraction | ATP attaches to ATPase on the myosin head Hydrolysis to release ADP and Pi during power stroke, allows myosin heads pull the actin filaments Needed for myosin head to detach Protein synthesis Ca 2+ pumps in SR |
Internal organs affected by SNS/PNS | Heart Lungs Liver Intestines |
How is the heart affected in the PNS/SNS | Slow HR vs. fast HR |
How are the lungs affected by the PNS/SNS | Shallow breaths vs deep breaths |
How is the liver affected by the PNS/SNS | Glucose take up (glycogenesis) vs glucose used up (glycolysis) |
How is the stomach affected by the PNS/SNS | More peristalsis vs. less |
How does the SNS affect smooth muscle | Alters blood flow to increase bp Vasoconstriction Peristalsis slows down Relaxes in airways (increases diameter) Pupils dilate |
How does the SNS affect cardiac muscle | Heart beats faster | Beats w/ more force |
How does SNS affect voluntary muscles | Glycogenolysis in muscles for priming Diaphragm contracting faster More blood flow to skeletal muscle --> respiration |
Long term effects of chronic stress | Cardiovascular problems due to high bp | Suppression of immune system leads to susceptibility to disease |
Photoperiodism | Plants' sensitivity to a lack of light, affects several diff plant responses e.g. flowering |
Phytochrome | Light sensitive pigment that affects the sensitivity of plants to light Exists in two forms, Pt and Pft |
How do plants prevent freezing | Cytoplasm and vacuole contain sap that lowers the freezing point Produce biological molecules (excluding lipids) to prevent cytoplasm freezing or protect cells from damage if they do freeze |
Commercial uses of plant hormones | Ethene to control ripeneing Hormone rooting powders and micropropagation Auxin to produce seedless fruit Cytokinins to prevent aging Gibberellins to improve size and shape |
Transverse tubules | Extensions into sarcolemma |
Factors affecting stomatal closure | Temperature | Water availability |
How does increases in temp affect stomata | Release of ABA decreases Stomata open Allows plant to cool through water evaporation |
How does decrease in water availability affect stomatal | Increased release of ABA Stomata close Reduces water loss through transpiration |
How do gibberellins cause stem elongation | Promote cell elongation - by loosening cell walls | Promote cell division - producing proteins that control the cell cycle |