Rigor Mortis and Muscle Physiology

The video provides an in-depth explanation of rigor mortis, a postmortem change characterized by muscle stiffness. It covers the biochemical processes involved, the phases of rigor mortis, and factors affecting its development. The video also discusses the role of ATP in muscle contraction and relaxation, the shift to anaerobic metabolism, and the timeline of rigor mortis. Additionally, it offers guidance on body care before rigor mortis sets in and includes review questions to reinforce learning.

What is the 'classic triad' of postmortem changes?

• Primary Flaccidity, Rigid Stage, Secondary Flaccidity

• Decomposition, Autolysis, Putrefaction

• Livor Mortis, Rigor Mortis, Algor Mortis

• Calcium Release, Muscle Contraction, ATP Depletion

Which phase of rigor mortis involves the muscles becoming fully relaxed?

• Primary Flaccidity

• Rigor Mortis

• Secondary Flaccidity

• Postmortem Autolysis

What triggers the muscle contraction cycle during rigor mortis?

• Binding of calcium ions to troponin

• Detachment of actin-myosin cross-bridges

• Release of sodium ions

• Increase in intracellular pH

What happens to ATP production as circulation stops after death?

• It increases due to aerobic metabolism

• It stops immediately

• It remains constant

• It decreases due to a shift to anaerobic metabolism

Which of the following factors does NOT affect the development of rigor mortis?

• Color of the skin

• Presence of sepsis

• Environmental conditions

• Body temperature

What is the recommended position for a body before rigor mortis sets in?

• Standing position with arms at sides

• Sitting position with head elevated

• Supine position with arms and legs aligned

• Prone position with arms and legs aligned

In which order does rigor mortis typically progress in the body?

• From the torso to the limbs

• From the limbs to the torso

• From small muscle groups to larger ones

• From larger muscle groups to smaller ones

What is the role of ATP in muscle relaxation during rigor mortis?

• It prevents lactic acid build-up

• It increases calcium ion concentration

• It detaches myosin from actin, allowing relaxation

• It binds to actin, causing muscle contraction

What happens when ATP is entirely consumed after death?

• Lactic acid production stops

• Irreversible actin-myosin cross-bridges form

• Muscles remain relaxed

• Calcium ions are released from the sarcoplasmic reticulum

Which statement best describes the role of lactic acid in rigor mortis?

• It increases ATP production

• It stops glycolysis

• It prevents calcium ion release

• It decreases intracellular pH, leading to muscle stiffness