Exercises: Effector organs

Name the two types of effector organs that execute the body's responses and give a specific example of how each acts in the same dangerous situation.

Explain what hormones are, which organs produce them, and how they reach the target cells they act upon.

State whether these structures are muscles, bones, or endocrine glands, and what effector function each performs: biceps, femur, thyroid, diaphragm, adrenal glands.

Describe how bones, joints, and muscles work together when you bend your arm to lift a bottle of water, indicating what each element contributes to the movement.

Diagrams A and B represent the same arm with the two muscles that move the forearm, marked with ?: in each case, one appears thickened (contracted) and the other stretched (relaxed). State which muscle (biceps or triceps) is contracted in each diagram and, taking into account that skeletal muscles can only pull and not push, explain why bending and straightening the forearm requires the coordinated action of both and what this type of muscle pair is called.

Compare the body's muscular response and hormonal response: which is faster, which lasts longer, how the signal arrives in each case, and give an everyday example of each type.

In an experiment, a laboratory animal is given a drug that specifically blocks adrenaline receptors in liver and bronchial cells, but does not affect its heart or nervous system. In the sudden presence of a predator:

1. a) Predict what difficulties its skeletal muscles will have in sustaining an intense and prolonged run, justifying your answer based on cellular respiration and the substances it requires.
2. b) A researcher states: "Since motor nerves continue to order the muscles to contract, the animal will run just as fast and for the same amount of time." Refute this statement, explaining why the alarm response to a danger requires the coordinated action of the endocrine system and not just the nervous system.

In a medical laboratory, the blood glucose level (blood glucose concentration) of two patients is analyzed while fasting and two hours after eating an identical breakfast rich in carbohydrates:

• Patient A: 0.9 g/L fasting → 1.1 g/L after two hours.

• Patient B: 1.4 g/L fasting → 2.4 g/L after two hours.

1. a) Interpret these results and identify, justifying your deduction, which of the two patients has a failure in the functioning of the pancreas as an endocrine effector.
2. b) A classmate claims: "The patient with higher values has more glucose in their blood, so their muscle cells will have much more energy available to exercise." Reasonably refute their statement, explaining what insulin actually does in target cells and what real cellular consequence occurs if this hormone is not administered.

An athlete suffers a complete rupture of the Achilles tendon, the structure that connects the gastrocnemius (calf) muscle to the calcaneus (heel bone). When trying to stand on tiptoe:

1. a) The gastrocnemius muscle receives the motor command, shortens, and bulges visibly, but the heel does not lift off the ground at all. Justify this biomechanical fact by explaining which link in the transmission chain has failed and what happens to the force generated by the muscular contraction.
2. b) A friend of the athlete proposes: "So that they can walk while recovering, let's lock their ankle with a rigid plaster cast; that way the calf muscle can lean on the cast and lift the heel." Refute this proposal biomechanically, explaining the essential role that both the tendon and the movable joint play in the lever system of the musculoskeletal system.