Bone Cells & Bone Health
How many bones are in the human body?
206
What connects muscle to bones?
Tendons
Define joint and their main jobs
Location where two or more bones meet. Allow bones to bend, twist, rotate, and move.
Define flexion
The movement that decreases the angle between two bones or body parts at a joint, essentially bending a limb or body segment
Why do girls feel awkward or less coordinated during puberty?
Bones grow faster than muscles, and hormones like estrogen loosen joints, making movement feel unstable.
Why do long bones have both compact and spongy layers?
Compact bone gives strength; spongy bone absorbs shock and holds bone marrow.
What muscle pair controls bending and straightening your arm?
Biceps and triceps
Name the 3 types of joints
Fixed, Semi-moveable, and moveable
What’s the difference between medial and lateral rotation?
Medial = turning inward (toward midline); lateral = turning outward (away from midline).
Name 2 commonly tight areas in female athletes
Hip flexors, hamstrings, calves
Define osteoblast and osteoclast. What happens when osteoclast activity is higher than osteoblast activity?
Osteocytes are immature cells that grow new bone; osteoblasts are mature cells that maintain it. Bones get weaker because more bone is broken down than built.
Identify the 3 types of muscle in the human body and whether they're involuntary and voluntary.
Cardiac (involuntary), skeletal (voluntary), and smooth (involuntary)
Why is tearing the ACL such a serious injury for athletes?
The ACL is the main ligament that stabilizes the knee, so without it the knee becomes wobbly during running, jumping, and quick direction changes. The knee can collapse or shift during high-impact movements.
A softball pitcher moves her arm in a full windmill motion before releasing the ball. What movement is this?
Circumduction
Based on the small-group guide, why does widening of the hips during puberty cause soreness or clumsiness?
Hip widening changes balance, posture, and leg alignment, which can cause knee or foot soreness and a feeling of clumsiness.
Why does bone marrow matter for athletes?
It produces blood cells, which carry oxygen and help healing and recovery.
When girls skip sleep or rest days, they tend to feel weaker the next day. Why does lack of sleep affect muscle strength even more than missing training?
Muscles rebuild and repair during sleep, so without it they cannot recover or strengthen.
Name the 4 types of movable joints
Hinge joint
Ball and socket joint
Pivot joint
Gliding joint
What is the difference between elevation and depression (as movements)?
Elevation = moving upward (shrug shoulders); Depression = moving downward (drop shoulders).
Describe in detail the Female Athlete triad.
A condition seen in active girls/women made of three connected problems caused by not eating enough for how much they train.
The 3 Components:
Low Energy Availability – not enough fuel to support training + body functions.
Menstrual Dysfunction – irregular or missing periods from low estrogen.
Low Bone Density – weak bones, stress fractures, early osteoporosis risk.
Under-fueling → hormones drop → periods change → bones weaken.
Why do calcium and vitamin D always need to be paired together?
Calcium builds bone; Vitamin D helps the body absorb calcium.
Name 3 reasons why tight muscles increase injury risk in girl athletes?
Tight muscles reduce range of motion, can’t absorb shock, and force other muscles to compensate.
True or False: Most sport injuries come from bones, not joints.
False. Most sports injuries affect the soft tissues around joints—muscles, ligaments, tendons—causing sprains and strains, rather than direct bone breaks (fractures). This is largely due to movement & stress, overuse, impact & twisting
Girls often notice soreness in the knees during growth because their quadriceps and hamstrings tighten.
What movement at the knee becomes uneven due to muscle imbalance, and why does this irritate the joint?
Knee extension vs. flexion becomes imbalanced
Unequal forces pull the kneecap and joint surfaces in different directions, causing pain.
Define osteoporosis and what makes osteoporosis dangerous for female athletes later in life?
Osteoporosis: a medical condition in which the bones become brittle and fragile from loss of tissue, typically as a result of hormonal changes, or deficiency of calcium or vitamin D.
Weak, brittle bones increase fracture risk, especially without strong bone density built in youth.