Produces blood cells (which carry oxygen around the body and white blood cells (which help to protect the body from infection)
Bones
Strong and hard
Provide protection
Provide support
Allow movement
Muscles are attached to bones via tough bands called tendons
Muscle contraction
Applies a force to the bone it's attached to, which makes the bone move
Muscles
Found in pairs around a joint
Work antagonistically to allow movement
Calculating the moment of a force
1. Identify the pivot point
2. Perpendicular force x perpendicular distance = moment
3. Muscle force must counteract the moment of the weight to keep the arm still
The muscle is 0.05m from the pivot, so the force it must apply is 3.6Nm / 0.05m = 72N
Menstrual cycle
Series of events in the female reproductive system that occurs over approximately 28 days
Stages of the menstrual cycle
1. Bleeding starts as the lining of the uterus breaks down
2. Lining of uterus starts to build up again
3. Egg is released from the ovaries (ovulation)
4. Lining of uterus remains thick awaiting implantation of a fertilised egg, if this doesn't happen then the lining breaks down and the cycle starts again
