It’s Like Pulling Teeth, Case Study Example

Part I

Humans are classed as endotherms.  Endotherms are animals that maintain their body temperature within a narrow and steady range brought about from internal heat production and controlled heat dissipation. The process of endothermy is controlled by metabolism, which is energy production within the cells themselves. Most heat in the body is produced by the mitochondria. The role of the mitochondria is to control metabolism by regulating the majority of intracellular energy production. Energy is generated in the mitochondria when it switches positively charged protons and negatively charged electrons between molecules.  These processes are called hydrolysis and oxidation.  Hydrolysis is when one molecule of ATP in the synthesis cycle gains one electron and is then balanced by a proton from a molecule of water. In contrast, oxidation is when the mitochondria gives a proton back to the water molecule and the water molecule, in turn passes their electrons to other molecules.

In Mr. Thompson’s case, most of the heat was generated by the skeletal muscles in his body. He was described as having strong contractions throughout his body.

The halothane caused a drastic increase in Mr. Thompson’s intracellular calcium levels and thus, caused muscle contractions throughout the body. Halothane increases the affinity for the skeletal muscles to store more calcium. The extra calcium must then be used up and this process requires more ATP be used. This is what generates this huge amount of heat.

This process is called glycogenosis.  Occurring in the cell, this process converts glycogen to a compound, glucose-1-phosphate. This compound then takes part in the energy production cycle within the cell which involves creatine phosphate and ATP.

Part II

An action potential enters the presynaptic terminal- The action potential enters the presynaptic terminal in the neuron and travels down to the axon.

Voltage gated channels open and Na2+and Ca2+ ions enters the presynaptic cell because its concentration is greater outside the cell than inside.

Ca2+ ions cause vesicular membrane to fuse with the presynaptic membrane.  The Ca2+, by binding with calmodulin, causes vesicles filled with neurotransmitter to flow towards the presynaptic membrane.

Neurotransmitter is liberated into the synaptic cleft. The neurotransmitter diffuses through the synaptic cleft.

Part III

Acetylcholine is secreted onto the cleft by the motor neuron.

The neurotransmitter reacts with the vesicles on the muscles membrane.

Channels open and muscle membranes closes. The neurotransmitter is broken down by the presynaptic membrane in the synaptic cleft.

This produces an action potential in the muscle. The action potential is taken up into the presynaptic cell.

Part IV

Acetylcholine binding opens the channels and the muscle membranes becomes open.

This creates an action potential which travels along the muscles surface.

The action potential travels down the neuron and stimulates voltage sensitive ion channels.

Calcium ions are released into the sarcoplasm from the sodium channels.

Calcium binds to the receptors.

Acetylcholine moves to expose the myosin binding sites on actin.

Cross bridge cycling causes the sarcomeres to contract.

Calcium is taken up into the sarcoplasmic reticulum to terminate the contraction.

Part V

The halothane is most likely to affect the calcium ions being released into the sarcoplasm and the calcium being taken up into the sarcoplasmic reticulum. Mr. Thompson likely has the condition malignant hyperthermia. This is a genetic defect that causes a life threatening reaction to certain medications, especially when administered in a cold environment. Since this condition affects the individuals ability to sustain normal calcium levels in the muscles, these are the two steps that would be affected the most by halothane.