Name the disorder that fits each case. A man has a swollen, painful joint of the big toe…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Name the disorder that fits each case.
- A man has a swollen, painful joint of the big toe. A test of the joint fluid shows crystals of uric acid.
- A woman has weak muscles that tire quickly. Her own antibodies attack the neuromuscular junction.
- A boy has muscles that degenerate step by step. A gene is at fault.
- A patient has rapid spasms of muscles. A test shows a low level of calcium ions in the body fluid.
- An old woman breaks a bone in a small fall. Her bones have lost mass, and her oestrogen level is low.
Need a reminder? The key ideaShow
Joints are fibrous (no movement), cartilaginous (limited) or synovial (much movement: ball and socket, hinge, pivot, gliding, saddle). Myasthenia gravis, muscular dystrophy and tetany affect muscle. Arthritis, osteoporosis and gout affect joints and bones. For a lever at rest, effort times its distance from the fulcrum equals load times its distance from the fulcrum.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Gout. Uric acid crystals collect in the joint and make it inflamed.
Step 2. (b) Myasthenia gravis. It is an autoimmune disorder of the neuromuscular junction.
Step 3. (c) Muscular dystrophy. The skeletal muscle degenerates step by step, mostly for a genetic reason.
Step 4. (d) Tetany. A low level of Ca in the body fluid causes the spasms.
Step 5. (e) Osteoporosis. Bone mass falls with age, and a fall in oestrogen is a common cause.
Answer: (a) gout; (b) myasthenia gravis; (c) muscular dystrophy; (d) tetany; (e) osteoporosis.
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