A&P human anatomy open ended questions

Say what a herniated disc is, and why the lower back is where it usually happens.

A herniated disc is when the soft gel in the center of an intervertebral disc pushes through a tear in its outer ring and presses on a nearby spinal nerve. It usually happens in the lower back because the lumbar region carries most of the body's weight and takes the biggest force when lifting, bending, or twisting.

A friend's knee X-ray shows worn cartilage and the knee hurts. Say which tissue is most likely sending the pain, and why the worn cartilage itself cannot.

The synovial membrane is sending the pain because it has nerves and blood vessels that gets irritated when the joint is stressed. The worn articular cartilage cannot feel anything on its own since it has no nerves and cannot send pain signals.

Your own words, two sentences. A toddler was lifted by one hand and now will not turn her palm up. Name the joint that was hurt and its type, and say what slipped out of place.

The injury is at the proximal radioulnar joint which is a pivot joint. The head of the radius slipped partly out from under the anular ligament which is what is making it painful to turn the palm up.

Your own words, two sentences. A drug holds some myosin heads back from actin. Explain what still happens in the sarcomere when the muscle contracts, and why it pulls with less force.

When the muscle contracts the unaffected myosin heads still bind to actin and perform their power strokes allowing the sarcomere to shorten as the thin filaments slide inward. But because fewer total myosin heads are actively forming cross-bridges, fewer parallel force generating contacts pull on the actin filament, which is why there's an overall reduction in muscular force.

Your own words, two sentences. A drug stops the sarcoplasmic reticulum from releasing calcium. Predict whether the muscle contracts when its nerve fires, and explain why.

The muscle will fail to contract when its nerve fires because blocking calcium release from the sarcoplasmic reticulum prevents that troponin from uncovering the myosin binding sites on actin. Without exposed binding sites cross-bridge cycling and force generation cannot take place.

Your own words, two sentences. A patient spends six weeks in a leg cast. When it comes off, the calf is thinner and weaker. Say what happened inside the muscle fibers, and what will rebuild them.

Disuse causes muscle protein degradation to outpace synthesis, leading to myofibril atrophy and reduced fiber cross-sectional area. Progressive resistance training and mechanical loading will stimulate protein synthesis and rebuild the muscle fibers.

Your own words, two sentences. A patient's calcaneal tendon is torn completely, yet lying on a table the patient can still point the foot down. Explain which muscles do it, and why the patient cannot rise on tiptoe on that leg.

The patient can still plantarflex using other posterior compartment muscles whose tendons pass anterior to the ankle's axis of rotation, such as the tibialis posterior, flexor digitorum longus, and flexor hallucis longus. But the patient cannot rise on tiptoe because the primary power source for that action, the gastrocnemius and soleus acting through the calcaneal tendon, is disconnected, preventing the transmission of force to lift the heel off the ground.

Your own words, two sentences. A patient's peripheral nerves lose their myelin and regain it over months. Name the cell that rebuilds it, and explain why the same loss inside the spinal cord is usually not repaired

Schwann cells rebuild myelin in the peripheral nervous system, whereas oligodendrocytes handle myelination in the central nervous system. The central nervous system environment inhibits axon regeneration and lacks the same supportive cellular pathways.

Your own words, two sentences. A pinprick and a deep cut both fire the same pain fiber. Explain why the deep cut does not produce bigger action potentials, and how the fiber tells the brain the cut was worse.

Action potentials are all-or-none events that always reach the same peak height regardless of stimulus strength. Instead of changing amplitude, a deep cut increases the frequency of action potentials firing along the nerve fiber to signal greater intensity to the brain.

Your own words, two sentences. A neuron receives one EPSP from each of three different axons at the same moment, and none of the three alone is big enough to reach threshold. Explain what decides whether the neuron fires, and name the kind of adding that is going on.

Whether a neuron fires depends on whether the combined depolarization reaches the trigger zone's threshold voltage. The type of adding taking place simultaneously from multiple spatial locations is called spatial summation.

Your own words, two sentences. A friend asks whether creatine would help more on a ten-second sprint up the stairs or a thirty-minute walk. Say which, and why, naming the source of ATP each one relies on most.

Creatine would help more with a ten-second sprint up the stairs because it quickly regenerates ATP by using the phosphagen system to fuel short, explosive bursts of activity. Compared to a thirty-minute walk, which relies mostly on aerobic respiration supported by oxidative metabolism.

Your own words, two sentences. Someone is given naloxone after an overdose, their breathing returns, and the deep sedation stays because a second drug is also present. Explain why the naloxone did not end the sedation.

Naloxone successfully reverses opioid receptor-mediated respiratory depression, but it does not affect non-opioid receptors. The persistent sedation is caused by a second adulterant acting independently on adrenergic receptors rather than opioid pathways.