Topic 7 Flashcards
Describe how the concentration of calcium ions around the myofibrils is controlled
-calcium ions released from the sarcoplasmic reticulum
- in response to {nerve impulses/ action potential/ depolarisation { at the neuromuscular junction
- calcium channels open to allow calcium ions to cross the membrane
- calcium ions taken back up into the sarcoplasmic reticulum by active transport
Calcium ions are required for muscle contraction. Describe the role of calcium ions in the contraction of muscle fibres
calcium ions { bind } to the troponin
- tropomyosin is { displaced / shape altered }
- exposing myosin binding sites on actin
The thick filament in a myofibril contains myosin. The myosin head contains the enzyme ATPase. Explain the importance of the primary structure for the functioning of this enzyme
-primary structure determines interaction between amino acids and r groups
-determines folding of tertiary structure
-therefore affects shape of active site
- active site is complements to atp
Explain how the extensor and flexor muscles bring about movement of the lower leg.
- tendons attach muscles to bones
- flexor and extensor muscles act as an antagonistic pair
- when the { extensor muscle contracts it pulls on the tibia to extend the leg/ flexor muscle contracts, it pulls on the fibula flexing the leg
Describe two structural differences between fast twitch muscle fibres and slow twitch muscle fibres
fast twitch fibres have { no/few } mitochondria, slow twitch fibres have many mitochondria
- fast twitch fibres have { no/few } capillaries present, slow twitch fibres have many capillaries present
Explain how the structure of a muscle fibre is related to its specialised function.
-cell surface membrane contains voltage gated channel to allow depolarising of muscle fibres
- many mitochondria for aerobic respiration to supply ATP
-presence of myosin and actin
-allow contraction of muscles
Explain the effect of increasing calcium ion concentration on the mean force produced by muscle fibres
-As calcium ion concrentraion increase force produced increase
-because more actin and myosin interact
-myosin bindin sites are exposed
Explain why it is necessary for the cardiac output of marathon runners to increase during a race
- increase supply of oxygenated blood to muscles
- to allow aerobic respiration
- to provide more energy to meet the increased energy demands
Deduce how adrenaline can cause a change in heart rate
-Adrealine carried in the blood
-acts on SAN node
-increases the frequency of impulses produced by SAN
- increases the rate at which heart contracts
Deduce the effect of beta-blockers on the supply of blood to muscle during exercise
-larger the dose the greater the decrease in heart
-reducing the heart rate reducing the cardiac output
-therefore reducing the supply of blood to muscle
Explain how starting to exercise causes an increase in breathing rate
exercise initiates impulses from the { motor cortex/stretch receptors in muscle }
- impulses sent to or from the { ventilation centre/respiratory control centre/medulla oblongata }
- leading to increased impulses to the { intercostal muscles/diaphragm
The demand for oxygen changes during exercise.
The change in demand affects the breathing rate.
Explain the effect of exercise on the changes in oxygen consumption
exercise will increase oxygen consumption
- because there is increased aerobic respiration
- because more { energy/ATP } needed by the muscles
- oxygen is required to convert { lactic acid } into { glucose/pyruvate}
- oxygen consumption begins to decrease after exercise
Describe how a spirometer trace can be used to calculate the respiratory minute ventilation
-find the difference in peak trough volume to give tidal volume
- find ventilation rate
-multiply tidal volume by ventilation rate
Describe how a spirometer trace can be used to calculate oxygen consumption per minute
-difference in volume of one peak compared to subsequent one
-description of time calculation to produce a value per min
Describe how thermoregulatory mechanisms are controlled to help marathon runners avoid heat stress
-thermoreceptors in hypothalamus/skin detect increase in temp
-theremoregulatory centre in hypthluamus stimulated
-sends impulse to sweat glands
-increase blood flow to surface of skin by vasodilation
Explain the role of the brain in reducing the heart rate after exercise
-chemoreceptors detect a change in ph
- cardiovascular control centre receives impulse from chemorecptors therefore impulses are transmitter along the pns
-to SAN reducing heart rate
Describe how the brain reduces the activity of the sweat glands after the exercise.
-theremocreptors detect a decrease in temperature
-hypothalamus send fewer impulses to swear glands
Explain why too much exercise could be harmful to the human body
-increased excerise results in wear and tear of join/tendons/ligaments
-therefore leading to joint damage
-suppression off immune system lead to risk of infection
Name two molecules needed for aerobic respiration that can move into the mitochondria
Pyruvate
Oxygen
Reduced NAD/ADP