Wolff's law describes what?

Bone remodelling itself in response to the loads placed on it

The rate at which muscle is lost with age

How joints lose fluid overnight

The relationship between height and weight

Sweating cools the body by which mechanism?

Evaporation from the skin, which carries heat away with the departing water

The sweat itself being cooler than the body

Widening of blood vessels in the gut

Reducing the amount of heat the body produces

Articular cartilage inside a joint has which notable property?

It has no blood supply of its own

It is packed with nerve endings

It regrows rapidly after injury

It is composed mainly of calcium

Agonist and antagonist muscles are best described as what?

A pair that act in opposition across the same joint

Two muscles that produce the same movement

The muscles of the heart and the gut

The largest and the smallest muscles in the body

What does the diaphragm do during breathing in?

It contracts and flattens, drawing air into the lungs

It filters dust from the incoming air

It warms blood returning to the heart

Spending weeks at high altitude produces which change in the blood?

More red blood cells, raising oxygen-carrying capacity

A permanent fall in blood volume

Staying balanced while standing still depends chiefly on which combination of inputs?

The inner ear, vision, and sensors in muscles and joints

Temperature receptors in the skin

A plyometric movement is one that does what?

Uses a rapid stretch immediately followed by a shortening contraction

Holds a fixed position without moving

Moves a joint through its range very slowly

Involves no ground contact at all

Warming up raises muscle temperature, which does what?

Speeds the chemical reactions supplying energy and makes tissue more pliable

Lowers heart rate back toward resting levels

Empties the muscles of stored fuel

Permanently increases lung volume

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Health & Fitness Medium ⚡ 10 Questions ⏱️ ~6 Mins +100 XP

The Body Under Load

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Bone thickens where it is loaded, cartilage has no blood supply, and sweat only cools you if it can evaporate. General physiology, no advice.

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About this topic

Living tissue is not passive material. Bone lays down more where it is repeatedly loaded and thins where it is not, which is why long spaceflight is a problem for the skeleton and why the racket arm of a career tennis player has measurably denser bone than the other. Tendon stores and returns elastic energy. Muscle adds contractile protein. The whole structure is continually being rebuilt around the demands placed on it. A few structures are exceptions, and the exceptions matter. Articular cartilage has no blood supply of its own and heals poorly for that reason. Cooling depends on evaporation rather than on sweat itself, so humid air defeats it. These questions cover that mechanical and thermal side of physiology — how the body handles load and heat, described rather than prescribed.

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The Body Under Load: all 10 questions and answers

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1Wolff's law describes what?
- A The rate at which muscle is lost with age
- B How joints lose fluid overnight
- C The relationship between height and weight
- D Bone remodelling itself in response to the loads placed on it Correct
Answer: D. Bone remodelling itself in response to the loads placed on it

Why: Julius Wolff set the idea out in the nineteenth century. It is why extended weightlessness in orbit reduces bone density and why loading is central to keeping it.
2Sweating cools the body by which mechanism?
- A Widening of blood vessels in the gut
- B Reducing the amount of heat the body produces
- C Evaporation from the skin, which carries heat away with the departing water Correct
- D The sweat itself being cooler than the body
Answer: C. Evaporation from the skin, which carries heat away with the departing water

Why: This is why humid air feels so much harder to work in. When the surrounding air is close to saturated, sweat runs off instead of evaporating and does almost nothing.
3Articular cartilage inside a joint has which notable property?
- A It is composed mainly of calcium
- B It has no blood supply of its own Correct
- C It is packed with nerve endings
- D It regrows rapidly after injury
Answer: B. It has no blood supply of its own

Why: Nutrients reach it by diffusion through joint fluid as the joint moves. That slow supply is a large part of why damage to it heals so poorly.
4Agonist and antagonist muscles are best described as what?
- A A pair that act in opposition across the same joint Correct
- B Two muscles that produce the same movement
- C The muscles of the heart and the gut
- D The largest and the smallest muscles in the body
Answer: A. A pair that act in opposition across the same joint

Why: The biceps and triceps are the standard pairing. Smooth movement depends on the antagonist releasing in step rather than simply switching off.
5What does the diaphragm do during breathing in?
- A It contracts to push air out
- B It filters dust from the incoming air
- C It warms blood returning to the heart
- D It contracts and flattens, drawing air into the lungs Correct
Answer: D. It contracts and flattens, drawing air into the lungs

Why: The lungs contain no muscle of their own. All the mechanical work of quiet breathing comes from the diaphragm and the muscles between the ribs.
6The hip and the shoulder are examples of which joint type?
- A Pivot
- B Saddle
- C Ball and socket Correct
- D Hinge
Answer: C. Ball and socket

Why: The shoulder trades stability for range of movement, since its socket is shallow. That is why it dislocates far more readily than the hip does.
7Spending weeks at high altitude produces which change in the blood?
- A Thicker white blood cells
- B More red blood cells, raising oxygen-carrying capacity Correct
- C Fewer red blood cells
- D A permanent fall in blood volume
Answer: B. More red blood cells, raising oxygen-carrying capacity

Why: The kidneys release more erythropoietin when oxygen is scarce. The adaptation takes weeks rather than days, and it reverses on return to sea level.
8Staying balanced while standing still depends chiefly on which combination of inputs?
- A The inner ear, vision, and sensors in muscles and joints Correct
- B The lungs and the diaphragm
- C The liver and the kidneys
- D Temperature receptors in the skin
Answer: A. The inner ear, vision, and sensors in muscles and joints

Why: Because the three sources are pooled, losing one is usually manageable and losing two is not. That is why closing the eyes on an unstable surface is far harder than closing them on firm ground.
9A plyometric movement is one that does what?
- A Holds a fixed position without moving
- B Moves a joint through its range very slowly
- C Involves no ground contact at all
- D Uses a rapid stretch immediately followed by a shortening contraction Correct
Answer: D. Uses a rapid stretch immediately followed by a shortening contraction

Why: Tendon stores elastic energy during the brief stretch and returns it. That is why a countermovement jump goes higher than one begun from a still squat.
10Warming up raises muscle temperature, which does what?
- A Empties the muscles of stored fuel
- B Permanently increases lung volume
- C Speeds the chemical reactions supplying energy and makes tissue more pliable Correct
- D Lowers heart rate back toward resting levels
Answer: C. Speeds the chemical reactions supplying energy and makes tissue more pliable

Why: Blood flow is redistributed toward working muscle at the same time. That redistribution takes a couple of minutes to settle, which is part of why the first minutes of hard effort feel worst.

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