Option B: Physiology of Exercise

M's pp Nerves Muscles and Movement.ppt (mydoc. word)

B1: Skeleton, Joints and Muscles

The skeleton is subdivided into axial and appendicular parts

Below is a skeleton showing the appendicular in red and axial in white

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Long bone showing hollow shaft and spongy head

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Diagram of an elbow joint

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Coordination of Muscle Activity

Note that the mysium referred to below is a connective tissue that supports the muscle structure. This connective tissue comes together to form the tendon.
1. The muscle is composed of several bundles,
2. Each bundle contains a group of muscle fibers.
3. Each individual muscle fiber is called a muscle cell and is multinucleate

4. Each muscle fiber consists of myofibrils which are made up repeating units called sarcomeres
5. The sarcomeres are the contracting unit of the muscle.
6. The sarcomeres of the myofibrils are made up of myofilaments called actin and myosin
7. The actin is a thin filament, while the myosin is a thick filament
8. The actin filaments slide across the myosin filaments , thus shortening the length of the sarcomere. Thousands of sarcomeres contract at a time, causing a full muscle contraction.
9. A contraction requires alot of energy (ATP) and many mitochondria can be seen between the myofibrils within the muscle cell (fiber)

A skeletal muscle showing several bundles of muscle fiber groups. each group is made up of several individual muscle fibers (muscle cells)

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A fascile bundle, containing groups of muscle fibers (muscle cells), with several myofibrils
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Fast twitch muscle fibers use oxygen/energy fast and may go into anaerobic respiration, thus acquiring an oxygen debt. There is less myoglobin/oxygen storage in fast muscles.

Slow tonic muscle fibers use oxygen more slowly for longer periods. There is more myoglobin/oxygen storage in slow muscles. Slow muscles do not go into oxygen debt, but they need glycogen reserves for longer and although they have high reserves of glycogen, they can deplete the glycogen stores.

B2 Muscles and Coordination

2.1 Outline the general organization of the Human NS: CNS (spinal cord and brain) and Peripheral NS (Nerves)

Nerves are bundles of individual neurons, rather like a cable of telephone wires. The neurons travel in both directions within the nerve cables; to the CNS (sensory neurons) and from the CNS (motor neurons).
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The Motor cortex in cerebral cortex of the brain sends impulse down spinal cord nerves to motor neurons.

2.2 Draw the structure of a sensory neuron and a motor neuron

The motor neuron sends the impulse to effector muscle or organ.

A chemical messanger carries the impulse across the synapse between the neuron and the muscle cell.

The muscle cell contracts when the stimulus is received.

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The sensory neurons send messages to the brain.

Proprioceptors are receptors in muscles, joints and tendons that pick up stimulii,such as pressure. stretch and position of the muscles, tendons and joints.

The proprioceptors pass this information on to the sensory neuron which relays the information to the CNS and the brain.

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=2.3 Outline synaptic transmission
Arrival of electrical impulse along neuron
  • release, diffusion and destruction of neurotransmitter substace across synaptic junction
  • propagation of subsequent electrical impulse at adjacent neuron(s)

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2.4 Explain how the contraction of a muscle is controlled by motor areas of the cerebral cortex, motor neurons, synapses, muscle fibers, and feedback to the brain by propriorecetptors and sensory receptors
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2.5 Explain how Inhibitory neurons coordinate the coordination of antagonistic muscles at a joint Sensory or interneurons forming a synapse with a motor neuron may further the propagation of an impulse or inhibit its propagation. The propagation of an impulse may be stimulated by a neurotransmitter at the synapase and inhibited by a meurotransmitter at another synapase. Below antagonistic muscle are shown to be stimulated and inhibited; for example, if the biceps is stimulated to flex the elbow joint, the triceps will be inhibited to relax

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Below The inhibitory neuron (A) is performing its usual task of slowing the flow of information through an antagonistic muscle neuron, while the neuron (B) in the presence of marijuana-like chemicals relax the inhibitory neuron's action.

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B3 Muscles and Energy

3.1 Explain how and why ventilation rate increases with exercise

Ventilation Rate = total volume of air taken into the lungs per minute (liters per minute), determined by number of breaths per minute x volume of air per breath

  • exercise increases metabolism
  • metabolism increases CO2 production (glucose + oxygen = water + carbon dioxide + chemical(ATP) and heat energy)
  • increased CO2 increases acidty, that is lowers pH of the blood.
  • lower pH deteced by chemoreceptors in arteries and message received by brain breathing center (medulla)
  • breathing center in brain sends nervous impulse to muscles of diaphragm amd intercostals to increase relaxation/contraction
  • ventilation rate increases

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Ventilation volume graph
Ventilation volume graph

The above graph shows how the ventilation rate changes during exercise. Pre-exercise is represented by "minus" time, zero onwards represents the time during exercise, while post-exercise is indicated by "plus" time in minutes.

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3.2 ,3.3 and 3.4 Explain cellular respiration (aerobic and anaerobic) including terms such as oxygen, lactate (lactic acid), oxygen debt, and ATP Know that sprinters use up their oxygen supply, while marathoners use up their glucose supply.

Read notes and handout notes

3.5 Myoglobin

  • has high affinity for oxygen,

  • therefore releases oxygen only when levels get very low.

  • Slow muscle fibers have increased myoglobin Haemoglobin

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3.6 Explain the role of Adrenalin in increasing levels of oxygen and glucose to the muscles external image endoc2.gif Acitvity and emotion can trigger the release of adrenalin hormone from the adrenal glands ino the blood stream. When adrenalin is relaeased into the blood stream, it causes the

  • glycogen stores in the liver to break down and release glucose
  • bronchioles in the lungs widen, to increase ventilation and oxygen diffusion into the blood
  • heart to increase, so blood can be pumped faster to the place it is needed
  • blood vessels to the muscles dialate, so more blood rich in glucose and oxygen can reach them - - the blood vessels to the skin, kidney, liver and digestive system constrict

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    http://www.howstuffworks.com/heart3.htm Cardiac conduction system
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3.7 Muscle Fatique


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Muscles feel fatiqued when

  • glycogen/glucose is used up from muscle fiber store
  • lactate accumulates in the blood

B4: Fitness and Training

  • See notes from presentations

B5: Injuries__

Visit this link to have injuries explained