Question

The appendectomy you are about to observe is of the patient, David Sims. He is an 18- year-old male who was healthy until two days ago when he began having severe abdominal pain, fever, and vomiting resulting in a diagnosis of appendicitis. David is in excellent health and has never had surgery before, so you anticipate the procedure to go smoothly.

"All of the patient's vital signs and lab work are within normal limits so we are good to go," says Dr. Hodges as David is brought into the operating room. After David has been sedated, Dr. Hodges places a special tube down his esophagus to measure his core body temperature and another in his trachea (an endotracheal tube) to help him breathe during the procedure. The case has been in progress for about 20 minutes when you notice David's heart rate jump up to 120 bpm, setting off the ECG alarm on the monitor. You are concerned and ask, "Can he feel what is happening? His heart rate just went up." Dr. Hodges looks at you and asks, "What is his core temperature?" You show her the chart and see that David's temperature has gradually begun to rise and is now 101.8° F (38.8° C). Dr. Hodges' face turns serious and she says, "His exhaled carbon dioxide levels have also begun to rise. We need to get the malignant hyperthermia cart right away!"

4. Malignant hyperthermia causes a hypermetabolic state in skeletal muscle, which is triggered by high demands for ATP during uncontrolled muscle contractions.

A. What is the role of ATP in cross bridge cycling?

B. What is the role of ATP in generating a resting membrane potential?

C. What is the role of ATP in maintaining calcium concentration gradients?

1. David's body temperature rises above normal during the surgery (hyperthermia). How does skeletal muscle tissue contribute to body temperature?

Answer 1

Question-1: 4. Malignant hyperthermia causes a hypermetabolic state in skeletal muscle, which is triggered by high demands for ATP during uncontrolled muscle contractions.

A). The energy consumed by the muscle during a maximal stimulus at optimal length is used for forming cross bridges (muscle contraction). The muscle consumes more energy as it receives maximal stimulus (repeated contraction and relaxation, more motor units are recruited).
Each myosin molecule contains a globular head and tail portion. The binding of ATP (adenosine triphosphate) to the head region of myosin hydrolyzes the ATP to ADP (adenosine diphosphate), releasing the phosphate bond; this hydrolysis provides the energy for muscle contraction. Then the thick myosin filaments slide over the thin stationary actin filaments.
B). During the resting state, the nerve cell is polarised. The interior of the cell is negatively charged, and it contains high concentrations of K+ ions. The exterior of the cell is positively charged, and it contains high concentrations of sodium ions. The resting membrane potential of a neuron is, -70 to -80mV (millivolts).
The movement of sodium and potassium ions occurs through the Na+/K+ ATPase pump, which needs ATP for its functioning.
C). Ca+2 ATPase decreases the cytosolic calcium levels and increase the calcium movement to the sarcoplasmic reticulum