Science - The body systems

• The ball and socket joints allow movements in all directions
• Saddle joints move back and forth, and up and down
• Condyloid joints allows side to side and up and down movements
• Gliding joints allow flat surfaces of the bone to slide over one another
• Pivot joints allows rotational movement
• Hinge joints allow bones to move in one direction
• The skeletal system is the framework of the human body.
• A human adult has 206 bones.
• Musculoskeletal system is composed of the skeletal and muscular systems.
• A cartilage is a firm and flexible tissue that is softer than bones.
• The skeleton has two major divisions, the axial skeleton, and the appendicular skeleton.
• The axial skeleton is represented by the head, neck, and trunk
• A ligament connects two bones.
• A tendon connects the bones and muscles.
• A joint is a point where two bones meet and are connected by a ligament.
• Immovable joints do not show any movement.
• Slightly movable joints have limited joints
• Freely movable joints, also known as synovial joints, allow a wide range of movement.
• Contraction happens when the muscle fiber becomes shorter and thicker.
• Relaxation happens when the muscle fiber returns to its original form.
• The three types of muscle tissues are skeletal, smooth, and cardiac muscle.
• Skeletal muscle is a muscle attached to the bones, it is a voluntary muscle.
• The smooth muscle is not attached to any bones.
• The cardiac muscle is another type of involuntary muscle that makes up the heart.
• Muscle strain results when a muscle is overstretched/muscle pull
• Sprain is a damage in the ligaments that may be caused by twisting of the joints.
• Carpal tunnel syndrome happens when the carpal ligament narrows in the wrist.
• Osteoporosis is the weakening of the bones
• The skin is the largest organ of the human body.
• The epidermis is the outermost and thinnest layer of the skin.
• Melanocytes is the cell that produce pigments called melanin that gives color to your skin.
• The dermis is the middle layer of the skin.
• Hypodermis or subcutaneous layer is filled with fat tissues.
• The hair follicle is divided into hair root and hair shaft.
• The hair root originates from the hypodermis and extends as a hair shaft.
• Nails protects the ends of the finger and toes.
• Acne develops when the pores on your skin are blocked.
• Keloid appears like an exaggerated scar.
• Scabies is a skin infestation by a parasite called itch mite.
• Hives, also known as urticaria, is characterized by swelling and itchiness.